diff --git a/.gitmodules b/.gitmodules
index 5c2363610..35aef82d3 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,7 +1,6 @@
 [submodule "lib/axtls"]
 	path = lib/axtls
-	url = https://github.com/pfalcon/axtls
-	branch = micropython
+	url = https://github.com/micropython/axtls.git
 [submodule "lib/libffi"]
 	path = lib/libffi
 	url = https://github.com/atgreen/libffi
diff --git a/LICENSE b/LICENSE
index 7f39931ba..5b5c37f7d 100644
--- a/LICENSE
+++ b/LICENSE
@@ -38,10 +38,6 @@ used during the build process and is not part of the compiled source code.
         /cc3000 (BSD-3-clause)
         /cc3100 (BSD-3-clause)
         /wiznet5k (BSD-3-clause)
-    /extmod
-        /crypto-algorithms (NONE)
-        /re15 (BSD-3-clause)
-        /uzlib (Zlib)
     /lib
         /asf4 (Apache-2.0)
         /axtls (BSD-3-clause)
@@ -52,6 +48,7 @@ used during the build process and is not part of the compiled source code.
         /berkeley-db-1xx (BSD-4-clause)
         /btstack (See btstack/LICENSE)
         /cmsis (BSD-3-clause)
+        /crypto-algorithms (NONE)
         /libhydrogen (ISC)
         /littlefs (BSD-3-clause)
         /lwip (BSD-3-clause)
@@ -60,9 +57,11 @@ used during the build process and is not part of the compiled source code.
         /nxp_driver (BSD-3-Clause)
         /oofatfs (BSD-1-clause)
         /pico-sdk (BSD-3-clause)
+        /re15 (BSD-3-clause)
         /stm32lib (BSD-3-clause)
         /tinytest (BSD-3-clause)
         /tinyusb (MIT)
+        /uzlib (Zlib)
     /logo (uses OFL-1.1)
     /ports
         /cc3200
diff --git a/docs/conf.py b/docs/conf.py
index 239934bfa..1a3c18a4f 100755
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -74,7 +74,7 @@ copyright = '- The MicroPython Documentation is Copyright © 2014-2021, Damien P
 #
 # We don't follow "The short X.Y version" vs "The full version, including alpha/beta/rc tags"
 # breakdown, so use the same version identifier for both to avoid confusion.
-version = release = '1.16'
+version = release = '1.17'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/docs/develop/library.rst b/docs/develop/library.rst
index bebddcc8a..47ea2dc8d 100644
--- a/docs/develop/library.rst
+++ b/docs/develop/library.rst
@@ -34,7 +34,7 @@ An example is the ``gc`` module discussed in :ref:`memorymanagement`.
    >>> gc.enable()
    >>>
 
-MicroPython has several other builtin standard/core modules like ``io``, ``uarray`` etc.
+MicroPython has several other builtin standard/core modules like ``io``, ``array`` etc.
 Adding a new core module involves several modifications.
 
 First, create the ``C`` file in the ``py/`` directory. In this example we are adding a
diff --git a/docs/develop/porting.rst b/docs/develop/porting.rst
index 59dd57000..549227d76 100644
--- a/docs/develop/porting.rst
+++ b/docs/develop/porting.rst
@@ -42,8 +42,8 @@ The basic MicroPython firmware is implemented in the main port file, e.g ``main.
    #include "py/gc.h"
    #include "py/mperrno.h"
    #include "py/stackctrl.h"
-   #include "lib/utils/gchelper.h"
-   #include "lib/utils/pyexec.h"
+   #include "shared/runtime/gchelper.h"
+   #include "shared/runtime/pyexec.h"
 
    // Allocate memory for the MicroPython GC heap.
    static char heap[4096];
@@ -106,10 +106,10 @@ We also need a Makefile at this point for the port:
    SRC_C = \
        main.c \
        mphalport.c \
-       lib/mp-readline/readline.c \
-       lib/utils/gchelper_generic.c \
-       lib/utils/pyexec.c \
-       lib/utils/stdout_helpers.c \
+       shared/readline/readline.c \
+       shared/runtime/gchelper_generic.c \
+       shared/runtime/pyexec.c \
+       shared/runtime/stdout_helpers.c \
 
    # Define the required object files.
    OBJ = $(PY_CORE_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
@@ -245,8 +245,8 @@ That should give a MicroPython REPL.  You can then run commands like:
 .. code-block:: bash
 
    MicroPython v1.13 on 2021-01-01; example-board with unknown-cpu
-   >>> import usys
-   >>> usys.implementation
+   >>> import sys
+   >>> sys.implementation
    ('micropython', (1, 13, 0))
    >>>
 
diff --git a/docs/esp32/quickref.rst b/docs/esp32/quickref.rst
index 77c7027c4..3153ebd57 100644
--- a/docs/esp32/quickref.rst
+++ b/docs/esp32/quickref.rst
@@ -98,7 +98,7 @@ A useful function for connecting to your local WiFi network is::
                 pass
         print('network config:', wlan.ifconfig())
 
-Once the network is established the :mod:`socket <usocket>` module can be used
+Once the network is established the :mod:`socket <socket>` module can be used
 to create and use TCP/UDP sockets as usual, and the ``urequests`` module for
 convenient HTTP requests.
 
@@ -113,7 +113,7 @@ to reconnect forever).
 Delay and timing
 ----------------
 
-Use the :mod:`time <utime>` module::
+Use the :mod:`time <time>` module::
 
     import time
 
@@ -361,7 +361,7 @@ accessed via the :ref:`machine.SoftI2C <machine.SoftI2C>` class::
     i2c.writeto(0x3a, '12') # write '12' to device with address 0x3a
 
     buf = bytearray(10)     # create a buffer with 10 bytes
-    i2c.writeto(0x3a, buf)  # write the given buffer to the slave
+    i2c.writeto(0x3a, buf)  # write the given buffer to the peripheral
 
 Hardware I2C bus
 ----------------
@@ -385,6 +385,24 @@ has the same methods as software I2C above::
     i2c = I2C(0)
     i2c = I2C(1, scl=Pin(5), sda=Pin(4), freq=400000)
 
+I2S bus
+-------
+
+See :ref:`machine.I2S <machine.I2S>`. ::
+
+    from machine import I2S, Pin
+    
+    i2s = I2S(0, sck=Pin(13), ws=Pin(14), sd=Pin(34), mode=I2S.TX, bits=16, format=I2S.STEREO, rate=44100, ibuf=40000) # create I2S object
+    i2s.write(buf)             # write buffer of audio samples to I2S device
+    
+    i2s = I2S(1, sck=Pin(33), ws=Pin(25), sd=Pin(32), mode=I2S.RX, bits=16, format=I2S.MONO, rate=22050, ibuf=40000) # create I2S object
+    i2s.readinto(buf)          # fill buffer with audio samples from I2S device
+    
+The I2S class is currently available as a Technical Preview.  During the preview period, feedback from 
+users is encouraged.  Based on this feedback, the I2S class API and implementation may be changed.
+
+ESP32 has two I2S buses with id=0 and id=1
+
 Real time clock (RTC)
 ---------------------
 
@@ -441,15 +459,15 @@ SD card
 
 See :ref:`machine.SDCard <machine.SDCard>`. ::
 
-    import machine, uos
+    import machine, os
 
     # Slot 2 uses pins sck=18, cs=5, miso=19, mosi=23
     sd = machine.SDCard(slot=2)
-    uos.mount(sd, "/sd")  # mount
+    os.mount(sd, "/sd")  # mount
 
-    uos.listdir('/sd')    # list directory contents
+    os.listdir('/sd')    # list directory contents
 
-    uos.umount('/sd')     # eject
+    os.umount('/sd')     # eject
 
 RMT
 ---
diff --git a/docs/esp8266/general.rst b/docs/esp8266/general.rst
index 4999bc2e9..be0437e75 100644
--- a/docs/esp8266/general.rst
+++ b/docs/esp8266/general.rst
@@ -117,7 +117,7 @@ Real-time clock
 
 RTC in ESP8266 has very bad accuracy, drift may be seconds per minute. As
 a workaround, to measure short enough intervals you can use
-``utime.time()``, etc. functions, and for wall clock time, synchronize from
+``time.time()``, etc. functions, and for wall clock time, synchronize from
 the net using included ``ntptime.py`` module.
 
 Due to limitations of the ESP8266 chip the internal real-time clock (RTC)
@@ -203,7 +203,7 @@ limitation with usage of TLS on the low-memory devices:
    communication with other devices.
 
 There are also some not implemented features specifically in MicroPython's
-``ussl`` module based on axTLS:
+``ssl`` module based on axTLS:
 
 6. Certificates are not validated (this makes connections susceptible
    to man-in-the-middle attacks).
diff --git a/docs/esp8266/quickref.rst b/docs/esp8266/quickref.rst
index bc648a348..9e64723b2 100644
--- a/docs/esp8266/quickref.rst
+++ b/docs/esp8266/quickref.rst
@@ -78,13 +78,13 @@ A useful function for connecting to your local WiFi network is::
                 pass
         print('network config:', wlan.ifconfig())
 
-Once the network is established the :mod:`socket <usocket>` module can be used
+Once the network is established the :mod:`socket <socket>` module can be used
 to create and use TCP/UDP sockets as usual.
 
 Delay and timing
 ----------------
 
-Use the :mod:`time <utime>` module::
+Use the :mod:`time <time>` module::
 
     import time
 
@@ -171,15 +171,15 @@ attaches the REPL).
 
 To detach the REPL from UART0, use::
 
-    import uos
-    uos.dupterm(None, 1)
+    import os
+    os.dupterm(None, 1)
 
 The REPL is attached by default. If you have detached it, to reattach
 it use::
 
-    import uos, machine
+    import os, machine
     uart = machine.UART(0, 115200)
-    uos.dupterm(uart, 1)
+    os.dupterm(uart, 1)
 
 PWM (pulse width modulation)
 ----------------------------
@@ -270,11 +270,11 @@ alias of :ref:`machine.SoftI2C <machine.SoftI2C>`)::
     # construct an I2C bus
     i2c = I2C(scl=Pin(5), sda=Pin(4), freq=100000)
 
-    i2c.readfrom(0x3a, 4)   # read 4 bytes from slave device with address 0x3a
-    i2c.writeto(0x3a, '12') # write '12' to slave device with address 0x3a
+    i2c.readfrom(0x3a, 4)   # read 4 bytes from peripheral device with address 0x3a
+    i2c.writeto(0x3a, '12') # write '12' to peripheral device with address 0x3a
 
     buf = bytearray(10)     # create a buffer with 10 bytes
-    i2c.writeto(0x3a, buf)  # write the given buffer to the slave
+    i2c.writeto(0x3a, buf)  # write the given buffer to the peripheral
 
 Real time clock (RTC)
 ---------------------
diff --git a/docs/esp8266/tutorial/intro.rst b/docs/esp8266/tutorial/intro.rst
index bbf0457ff..a5deb3532 100644
--- a/docs/esp8266/tutorial/intro.rst
+++ b/docs/esp8266/tutorial/intro.rst
@@ -109,10 +109,12 @@ PC.  You may also need to reduce the baudrate if you get errors when flashing
 that you have.
 
 For some boards with a particular FlashROM configuration (e.g. some variants of
-a NodeMCU board) you may need to use the following command to deploy
-the firmware (note the ``-fm dio`` option)::
+a NodeMCU board) you may need to manually set a compatible
+`SPI Flash Mode <https://github.com/espressif/esptool/wiki/SPI-Flash-Modes>`_.
+You'd usually pick the fastest option that is compatible with your device, but
+the ``-fm dout`` option (the slowest option) should have the best compatibility::
 
-    esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect -fm dio 0 esp8266-20170108-v1.8.7.bin
+    esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect -fm dout 0 esp8266-20170108-v1.8.7.bin
 
 If the above commands run without error then MicroPython should be installed on
 your board!
diff --git a/docs/esp8266/tutorial/repl.rst b/docs/esp8266/tutorial/repl.rst
index ba64fcccb..196541bd0 100644
--- a/docs/esp8266/tutorial/repl.rst
+++ b/docs/esp8266/tutorial/repl.rst
@@ -18,9 +18,9 @@ the REPL directly from your PC.  Otherwise you will need to have a way of
 communicating with the UART.
 
 To access the prompt over USB-serial you need to use a terminal emulator program.
-On Windows TeraTerm is a good choice, on Mac you can use the built-in screen
-program, and Linux has picocom and minicom.  Of course, there are many other
-terminal programs that will work, so pick your favourite!
+On Windows TeraTerm is a good choice, on Mac you can use the built-in ``screen``
+program, and Linux has ``picocom`` and ``minicom``.  Of course, there are many
+other terminal programs that will work, so pick your favourite!
 
 For example, on Linux you can try running::
 
@@ -37,9 +37,9 @@ WebREPL allows you to use the Python prompt over WiFi, connecting through a
 browser. The latest versions of Firefox and Chrome are supported.
 
 For your convenience, WebREPL client is hosted at
-`<http://micropython.org/webrepl>`__ . Alternatively, you can install it
+`<http://micropython.org/webrepl>`__. Alternatively, you can install it
 locally from the the GitHub repository
-`<https://github.com/micropython/webrepl>`__ .
+`<https://github.com/micropython/webrepl>`__.
 
 Before connecting to WebREPL, you should set a password and enable it via
 a normal serial connection. Initial versions of MicroPython for ESP8266
diff --git a/docs/index.rst b/docs/index.rst
index 58552daf5..a97bff1c8 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -14,3 +14,4 @@ MicroPython documentation and references
     rp2/quickref.rst
     wipy/quickref.rst
     unix/quickref.rst
+    zephyr/quickref.rst
diff --git a/docs/library/uarray.rst b/docs/library/array.rst
similarity index 87%
rename from docs/library/uarray.rst
rename to docs/library/array.rst
index 9fa82ff31..88d6d2263 100644
--- a/docs/library/uarray.rst
+++ b/docs/library/array.rst
@@ -1,7 +1,7 @@
-:mod:`uarray` -- arrays of numeric data
-=======================================
+:mod:`array` -- arrays of numeric data
+======================================
 
-.. module:: uarray
+.. module:: array
    :synopsis: efficient arrays of numeric data
 
 |see_cpython_module| :mod:`python:array`.
diff --git a/docs/library/ubinascii.rst b/docs/library/binascii.rst
similarity index 90%
rename from docs/library/ubinascii.rst
rename to docs/library/binascii.rst
index 721b80508..fc621a8ab 100644
--- a/docs/library/ubinascii.rst
+++ b/docs/library/binascii.rst
@@ -1,7 +1,7 @@
-:mod:`ubinascii` -- binary/ASCII conversions
-============================================
+:mod:`binascii` -- binary/ASCII conversions
+===========================================
 
-.. module:: ubinascii
+.. module:: binascii
    :synopsis: binary/ASCII conversions
 
 |see_cpython_module| :mod:`python:binascii`.
diff --git a/docs/library/ubluetooth.rst b/docs/library/bluetooth.rst
similarity index 97%
rename from docs/library/ubluetooth.rst
rename to docs/library/bluetooth.rst
index 3d435a7be..7ab4d6e88 100644
--- a/docs/library/ubluetooth.rst
+++ b/docs/library/bluetooth.rst
@@ -1,7 +1,7 @@
-:mod:`ubluetooth` --- low-level Bluetooth
-=========================================
+:mod:`bluetooth` --- low-level Bluetooth
+========================================
 
-.. module:: ubluetooth
+.. module:: bluetooth
    :synopsis: Low-level Bluetooth radio functionality
 
 This module provides an interface to a Bluetooth controller on a board.
@@ -110,7 +110,7 @@ Event Handling
 
     **Note:** As an optimisation to prevent unnecessary allocations, the ``addr``,
     ``adv_data``, ``char_data``, ``notify_data``, and ``uuid`` entries in the
-    tuples are read-only memoryview instances pointing to ubluetooth's internal
+    tuples are read-only memoryview instances pointing to :mod:`bluetooth`'s internal
     ringbuffer, and are only valid during the invocation of the IRQ handler
     function.  If your program needs to save one of these values to access after
     the IRQ handler has returned (e.g. by saving it in a class instance or global
@@ -293,7 +293,7 @@ For the ``_IRQ_PASSKEY_ACTION`` event, the available actions are::
     _PASSKEY_ACTION_NUMERIC_COMPARISON = const(4)
 
 In order to save space in the firmware, these constants are not included on the
-:mod:`ubluetooth` module. Add the ones that you need from the list above to your
+:mod:`bluetooth` module. Add the ones that you need from the list above to your
 program.
 
 
@@ -485,10 +485,14 @@ writes from a client to a given characteristic, use
     Reads the local value for this handle (which has either been written by
     :meth:`gatts_write <BLE.gatts_write>` or by a remote client).
 
-.. method:: BLE.gatts_write(value_handle, data, /)
+.. method:: BLE.gatts_write(value_handle, data, send_update=False, /)
 
     Writes the local value for this handle, which can be read by a client.
 
+    If *send_update* is ``True``, then any subscribed clients will be notified
+    (or indicated, depending on what they're subscribed to and which operations
+    the characteristic supports) about this write.
+
 .. method:: BLE.gatts_notify(conn_handle, value_handle, data=None, /)
 
     Sends a notification request to a connected client.
@@ -499,17 +503,20 @@ writes from a client to a given characteristic, use
     Otherwise, if *data* is ``None``, then the current local value (as
     set with :meth:`gatts_write <BLE.gatts_write>`) will be sent.
 
+    **Note:** The notification will be sent regardless of the subscription
+    status of the client to this characteristic.
+
 .. method:: BLE.gatts_indicate(conn_handle, value_handle, /)
 
-    Sends an indication request to a connected client.
-
-    **Note:** This does not currently support sending a custom value, it will
-    always send the current local value (as set with :meth:`gatts_write
-    <BLE.gatts_write>`).
+    Sends an indication request containing the characteristic's current value to
+    a connected client.
 
     On acknowledgment (or failure, e.g. timeout), the
     ``_IRQ_GATTS_INDICATE_DONE`` event will be raised.
 
+    **Note:** The indication will be sent regardless of the subscription
+    status of the client to this characteristic.
+
 .. method:: BLE.gatts_set_buffer(value_handle, len, append=False, /)
 
     Sets the internal buffer size for a value in bytes. This will limit the
diff --git a/docs/library/btree.rst b/docs/library/btree.rst
index ba9108521..c093f970f 100644
--- a/docs/library/btree.rst
+++ b/docs/library/btree.rst
@@ -22,7 +22,7 @@ Example::
 
     # First, we need to open a stream which holds a database
     # This is usually a file, but can be in-memory database
-    # using uio.BytesIO, a raw flash partition, etc.
+    # using io.BytesIO, a raw flash partition, etc.
     # Oftentimes, you want to create a database file if it doesn't
     # exist and open if it exists. Idiom below takes care of this.
     # DO NOT open database with "a+b" access mode.
diff --git a/docs/library/builtins.rst b/docs/library/builtins.rst
index 3029cd9e3..7a0229c2a 100644
--- a/docs/library/builtins.rst
+++ b/docs/library/builtins.rst
@@ -1,5 +1,5 @@
-Builtin functions and exceptions
-================================
+:mod:`builtins` -- builtin functions and exceptions
+===================================================
 
 All builtin functions and exceptions are described here. They are also
 available via ``builtins`` module.
diff --git a/docs/library/ucollections.rst b/docs/library/collections.rst
similarity index 91%
rename from docs/library/ucollections.rst
rename to docs/library/collections.rst
index b833842c1..21f06fded 100644
--- a/docs/library/ucollections.rst
+++ b/docs/library/collections.rst
@@ -1,7 +1,7 @@
-:mod:`ucollections` -- collection and container types
-=====================================================
+:mod:`collections` -- collection and container types
+====================================================
 
-.. module:: ucollections
+.. module:: collections
    :synopsis: collection and container types
 
 |see_cpython_module| :mod:`python:collections`.
@@ -49,7 +49,7 @@ Classes
     a string with space-separated field named (but this is less efficient).
     Example of use::
 
-        from ucollections import namedtuple
+        from collections import namedtuple
 
         MyTuple = namedtuple("MyTuple", ("id", "name"))
         t1 = MyTuple(1, "foo")
@@ -63,7 +63,7 @@ Classes
     added. When ordered dict is iterated over, keys/items are returned in
     the order they were added::
 
-        from ucollections import OrderedDict
+        from collections import OrderedDict
 
         # To make benefit of ordered keys, OrderedDict should be initialized
         # from sequence of (key, value) pairs.
diff --git a/docs/library/ucryptolib.rst b/docs/library/cryptolib.rst
similarity index 73%
rename from docs/library/ucryptolib.rst
rename to docs/library/cryptolib.rst
index 79471c2e9..e02fb0d22 100644
--- a/docs/library/ucryptolib.rst
+++ b/docs/library/cryptolib.rst
@@ -1,7 +1,7 @@
-:mod:`ucryptolib` -- cryptographic ciphers
-==========================================
+:mod:`cryptolib` -- cryptographic ciphers
+=========================================
 
-.. module:: ucryptolib
+.. module:: cryptolib
    :synopsis: cryptographic ciphers
 
 Classes
@@ -21,9 +21,9 @@ Classes
             * *key* is an encryption/decryption key (bytes-like).
             * *mode* is:
 
-                * ``1`` (or ``ucryptolib.MODE_ECB`` if it exists) for Electronic Code Book (ECB).
-                * ``2`` (or ``ucryptolib.MODE_CBC`` if it exists) for Cipher Block Chaining (CBC).
-                * ``6`` (or ``ucryptolib.MODE_CTR`` if it exists) for Counter mode (CTR).
+                * ``1`` (or ``cryptolib.MODE_ECB`` if it exists) for Electronic Code Book (ECB).
+                * ``2`` (or ``cryptolib.MODE_CBC`` if it exists) for Cipher Block Chaining (CBC).
+                * ``6`` (or ``cryptolib.MODE_CTR`` if it exists) for Counter mode (CTR).
 
             * *IV* is an initialization vector for CBC mode.
             * For Counter mode, *IV* is the initial value for the counter.
diff --git a/docs/library/uerrno.rst b/docs/library/errno.rst
similarity index 78%
rename from docs/library/uerrno.rst
rename to docs/library/errno.rst
index 1d60c80e1..82303bfcb 100644
--- a/docs/library/uerrno.rst
+++ b/docs/library/errno.rst
@@ -1,7 +1,7 @@
-:mod:`uerrno` -- system error codes
-===================================
+:mod:`errno` -- system error codes
+==================================
 
-.. module:: uerrno
+.. module:: errno
    :synopsis: system error codes
 
 |see_cpython_module| :mod:`python:errno`.
@@ -20,9 +20,9 @@ Constants
     where ``exc`` is an instance of `OSError`. Usage example::
 
         try:
-            uos.mkdir("my_dir")
+            os.mkdir("my_dir")
         except OSError as exc:
-            if exc.errno == uerrno.EEXIST:
+            if exc.errno == errno.EEXIST:
                 print("Directory already exists")
 
 .. data:: errorcode
@@ -30,5 +30,5 @@ Constants
     Dictionary mapping numeric error codes to strings with symbolic error
     code (see above)::
 
-        >>> print(uerrno.errorcode[uerrno.EEXIST])
+        >>> print(errno.errorcode[errno.EEXIST])
         EEXIST
diff --git a/docs/library/esp32.rst b/docs/library/esp32.rst
index fc9096803..e3c25d265 100644
--- a/docs/library/esp32.rst
+++ b/docs/library/esp32.rst
@@ -91,7 +91,7 @@ methods to enable over-the-air (OTA) updates.
 
     These methods implement the simple and :ref:`extended
     <block-device-interface>` block protocol defined by
-    :class:`uos.AbstractBlockDev`.
+    :class:`os.AbstractBlockDev`.
 
 .. method:: Partition.set_boot()
 
diff --git a/docs/library/framebuf.rst b/docs/library/framebuf.rst
index 0073ba708..13502cc7a 100644
--- a/docs/library/framebuf.rst
+++ b/docs/library/framebuf.rst
@@ -103,16 +103,23 @@ Other methods
     Shift the contents of the FrameBuffer by the given vector. This may
     leave a footprint of the previous colors in the FrameBuffer.
 
-.. method:: FrameBuffer.blit(fbuf, x, y[, key])
+.. method:: FrameBuffer.blit(fbuf, x, y, key=-1, palette=None)
 
     Draw another FrameBuffer on top of the current one at the given coordinates.
     If *key* is specified then it should be a color integer and the
     corresponding color will be considered transparent: all pixels with that
     color value will not be drawn.
 
-    This method works between FrameBuffer instances utilising different formats,
-    but the resulting colors may be unexpected due to the mismatch in color
-    formats.
+    The *palette* argument enables blitting between FrameBuffers with differing
+    formats. Typical usage is to render a monochrome or grayscale glyph/icon to
+    a color display. The *palette* is a FrameBuffer instance whose format is
+    that of the current FrameBuffer. The *palette* height is one pixel and its
+    pixel width is the number of colors in the source FrameBuffer. The *palette*
+    for an N-bit source needs 2**N pixels; the *palette* for a monochrome source
+    would have 2 pixels representing background and foreground colors. The
+    application assigns a color to each pixel in the *palette*. The color of the
+    current pixel will be that of that *palette* pixel whose x position is the
+    color of the corresponding source pixel.
 
 Constants
 ---------
diff --git a/docs/library/uhashlib.rst b/docs/library/hashlib.rst
similarity index 84%
rename from docs/library/uhashlib.rst
rename to docs/library/hashlib.rst
index e1eddd2b7..e5d8dd880 100644
--- a/docs/library/uhashlib.rst
+++ b/docs/library/hashlib.rst
@@ -1,7 +1,7 @@
-:mod:`uhashlib` -- hashing algorithms
-=====================================
+:mod:`hashlib` -- hashing algorithms
+====================================
 
-.. module:: uhashlib
+.. module:: hashlib
    :synopsis: hashing algorithms
 
 |see_cpython_module| :mod:`python:hashlib`.
@@ -27,15 +27,15 @@ be implemented:
 Constructors
 ------------
 
-.. class:: uhashlib.sha256([data])
+.. class:: hashlib.sha256([data])
 
     Create an SHA256 hasher object and optionally feed ``data`` into it.
 
-.. class:: uhashlib.sha1([data])
+.. class:: hashlib.sha1([data])
 
     Create an SHA1 hasher object and optionally feed ``data`` into it.
 
-.. class:: uhashlib.md5([data])
+.. class:: hashlib.md5([data])
 
     Create an MD5 hasher object and optionally feed ``data`` into it.
 
@@ -53,5 +53,5 @@ Methods
 
 .. method:: hash.hexdigest()
 
-   This method is NOT implemented. Use ``ubinascii.hexlify(hash.digest())``
+   This method is NOT implemented. Use ``binascii.hexlify(hash.digest())``
    to achieve a similar effect.
diff --git a/docs/library/uheapq.rst b/docs/library/heapq.rst
similarity index 88%
rename from docs/library/uheapq.rst
rename to docs/library/heapq.rst
index 9ae1f61a1..5e808d544 100644
--- a/docs/library/uheapq.rst
+++ b/docs/library/heapq.rst
@@ -1,7 +1,7 @@
-:mod:`uheapq` -- heap queue algorithm
-=====================================
+:mod:`heapq` -- heap queue algorithm
+====================================
 
-.. module:: uheapq
+.. module:: heapq
    :synopsis: heap queue algorithm
 
 |see_cpython_module| :mod:`python:heapq`.
diff --git a/docs/library/index.rst b/docs/library/index.rst
index 2536e8dc9..070e9f966 100644
--- a/docs/library/index.rst
+++ b/docs/library/index.rst
@@ -7,47 +7,39 @@ MicroPython libraries
 
    Important summary of this section
 
-   * MicroPython implements a subset of Python functionality for each module.
-   * To ease extensibility, MicroPython versions of standard Python modules
-     usually have ``u`` ("micro") prefix.
-   * Any particular MicroPython variant or port may miss any feature/function
-     described in this general documentation (due to resource constraints or
-     other limitations).
-
+   * MicroPython provides built-in modules that mirror the functionality of the
+     Python standard library (e.g. :mod:`os`, :mod:`time`), as well as
+     MicroPython-specific modules (e.g. :mod:`bluetooth`, :mod:`machine`).
+   * Most standard library modules implement a subset of the functionality of
+     the equivalent Python module, and in a few cases provide some
+     MicroPython-specific extensions (e.g. :mod:`array`, :mod:`os`)
+   * Due to resource constraints or other limitations, some ports or firmware
+     versions may not include all the functionality documented here.
+   * To allow for extensibility, the built-in modules can be extended from
+     Python code loaded onto the device.
 
 This chapter describes modules (function and class libraries) which are built
-into MicroPython. There are a few categories of such modules:
+into MicroPython. This documentation in general aspires to describe all modules
+and functions/classes which are implemented in the MicroPython project.
+However, MicroPython is highly configurable, and each port to a particular
+board/embedded system may include only a subset of the available MicroPython
+libraries.
 
-* Modules which implement a subset of standard Python functionality and are not
-  intended to be extended by the user.
-* Modules which implement a subset of Python functionality, with a provision
-  for extension by the user (via Python code).
-* Modules which implement MicroPython extensions to the Python standard libraries.
-* Modules specific to a particular :term:`MicroPython port` and thus not portable.
-
-Note about the availability of the modules and their contents: This documentation
-in general aspires to describe all modules and functions/classes which are
-implemented in MicroPython project. However, MicroPython is highly configurable, and
-each port to a particular board/embedded system makes available only a subset
-of MicroPython libraries. For officially supported ports, there is an effort
-to either filter out non-applicable items, or mark individual descriptions
-with "Availability:" clauses describing which ports provide a given feature.
-
-With that in mind, please still be warned that some functions/classes
-in a module (or even the entire module) described in this documentation **may be
-unavailable** in a particular build of MicroPython on a particular system. The
-best place to find general information of the availability/non-availability
-of a particular feature is the "General Information" section which contains
-information pertaining to a specific :term:`MicroPython port`.
+With that in mind, please be warned that some functions/classes in a module (or
+even the entire module) described in this documentation **may be unavailable**
+in a particular build of MicroPython on a particular system. The best place to
+find general information of the availability/non-availability of a particular
+feature is the "General Information" section which contains information
+pertaining to a specific :term:`MicroPython port`.
 
 On some ports you are able to discover the available, built-in libraries that
-can be imported by entering the following at the REPL::
+can be imported by entering the following at the :term:`REPL`::
 
     help('modules')
 
 Beyond the built-in libraries described in this documentation, many more
 modules from the Python standard library, as well as further MicroPython
-extensions to it, can be found in `micropython-lib`.
+extensions to it, can be found in :term:`micropython-lib`.
 
 Python standard libraries and micro-libraries
 ---------------------------------------------
@@ -55,46 +47,33 @@ Python standard libraries and micro-libraries
 The following standard Python libraries have been "micro-ified" to fit in with
 the philosophy of MicroPython.  They provide the core functionality of that
 module and are intended to be a drop-in replacement for the standard Python
-library.  Some modules below use a standard Python name, but prefixed with "u",
-e.g. ``ujson`` instead of ``json``. This is to signify that such a module is
-micro-library, i.e. implements only a subset of CPython module functionality.
-By naming them differently, a user has a choice to write a Python-level module
-to extend functionality for better compatibility with CPython (indeed, this is
-what done by the `micropython-lib` project mentioned above).
-
-On some embedded platforms, where it may be cumbersome to add Python-level
-wrapper modules to achieve naming compatibility with CPython, micro-modules
-are available both by their u-name, and also by their non-u-name.  The
-non-u-name can be overridden by a file of that name in your library path (``sys.path``).
-For example, ``import json`` will first search for a file ``json.py`` (or package
-directory ``json``) and load that module if it is found.  If nothing is found,
-it will fallback to loading the built-in ``ujson`` module.
+library.
 
 .. toctree::
    :maxdepth: 1
 
+   array.rst
+   binascii.rst
    builtins.rst
    cmath.rst
+   collections.rst
+   errno.rst
    gc.rst
+   hashlib.rst
+   heapq.rst
+   io.rst
+   json.rst
    math.rst
-   uarray.rst
+   os.rst
+   re.rst
+   select.rst
+   socket.rst
+   ssl.rst
+   struct.rst
+   sys.rst
+   time.rst
    uasyncio.rst
-   ubinascii.rst
-   ucollections.rst
-   uerrno.rst
-   uhashlib.rst
-   uheapq.rst
-   uio.rst
-   ujson.rst
-   uos.rst
-   ure.rst
-   uselect.rst
-   usocket.rst
-   ussl.rst
-   ustruct.rst
-   usys.rst
-   utime.rst
-   uzlib.rst
+   zlib.rst
    _thread.rst
 
 
@@ -107,13 +86,14 @@ the following libraries.
 .. toctree::
    :maxdepth: 1
 
+   bluetooth.rst
    btree.rst
+   cryptolib.rst
    framebuf.rst
    machine.rst
    micropython.rst
+   neopixel.rst
    network.rst
-   ubluetooth.rst
-   ucryptolib.rst
    uctypes.rst
 
 
@@ -131,7 +111,7 @@ To access platform-specific hardware use the appropriate library, e.g.
 
 
 Libraries specific to the pyboard
----------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 The following libraries are specific to the pyboard.
 
@@ -143,7 +123,7 @@ The following libraries are specific to the pyboard.
 
 
 Libraries specific to the WiPy
-------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 The following libraries and classes are specific to the WiPy.
 
@@ -156,7 +136,7 @@ The following libraries and classes are specific to the WiPy.
 
 
 Libraries specific to the ESP8266 and ESP32
--------------------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 The following libraries are specific to the ESP8266 and ESP32.
 
@@ -168,7 +148,7 @@ The following libraries are specific to the ESP8266 and ESP32.
 
 
 Libraries specific to the RP2040
---------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 The following libraries are specific to the RP2040, as used in the Raspberry Pi Pico.
 
@@ -176,3 +156,34 @@ The following libraries are specific to the RP2040, as used in the Raspberry Pi
   :maxdepth: 2
 
   rp2.rst
+
+Libraries specific to Zephyr
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following libraries are specific to the Zephyr port.
+
+.. toctree::
+  :maxdepth: 2
+
+  zephyr.rst
+
+Extending built-in libraries from Python
+----------------------------------------
+
+In most cases, the above modules are actually named ``umodule`` rather than
+``module``, but MicroPython will alias any module prefixed with a ``u`` to the
+non-``u`` version. However a file (or :term:`frozen module`) named
+``module.py`` will take precedence over this alias.
+
+This allows the user to provide an extended implementation of a built-in library
+(perhaps to provide additional CPython compatibility). The user-provided module
+(in ``module.py``) can still use the built-in functionality by importing
+``umodule`` directly. This is used extensively in :term:`micropython-lib`. See
+:ref:`packages` for more information.
+
+This applies to both the Python standard libraries (e.g. ``os``, ``time``, etc),
+but also the MicroPython libraries too (e.g. ``machine``, ``bluetooth``, etc).
+The main exception is the port-specific libraries (``pyb``, ``esp``, etc).
+
+*Other than when you specifically want to force the use of the built-in module,
+we recommend always using ``import module`` rather than ``import umodule``.*
diff --git a/docs/library/uio.rst b/docs/library/io.rst
similarity index 98%
rename from docs/library/uio.rst
rename to docs/library/io.rst
index adbeef08b..6b4b9f1a4 100644
--- a/docs/library/uio.rst
+++ b/docs/library/io.rst
@@ -1,7 +1,7 @@
-:mod:`uio` -- input/output streams
-==================================
+:mod:`io` -- input/output streams
+=================================
 
-.. module:: uio
+.. module:: io
    :synopsis: input/output streams
 
 |see_cpython_module| :mod:`python:io`.
diff --git a/docs/library/ujson.rst b/docs/library/json.rst
similarity index 61%
rename from docs/library/ujson.rst
rename to docs/library/json.rst
index 5668eb21a..f1d6364f4 100644
--- a/docs/library/ujson.rst
+++ b/docs/library/json.rst
@@ -1,7 +1,7 @@
-:mod:`ujson` -- JSON encoding and decoding
-==========================================
+:mod:`json` -- JSON encoding and decoding
+=========================================
 
-.. module:: ujson
+.. module:: json
    :synopsis: JSON encoding and decoding
 
 |see_cpython_module| :mod:`python:json`.
@@ -12,14 +12,20 @@ data format.
 Functions
 ---------
 
-.. function:: dump(obj, stream)
+.. function:: dump(obj, stream, separators=None)
 
    Serialise *obj* to a JSON string, writing it to the given *stream*.
 
-.. function:: dumps(obj)
+   If specified, separators should be an ``(item_separator, key_separator)``
+   tuple. The default is ``(', ', ': ')``. To get the most compact JSON
+   representation, you should specify ``(',', ':')`` to eliminate whitespace.
+
+.. function:: dumps(obj, separators=None)
 
    Return *obj* represented as a JSON string.
 
+   The arguments have the same meaning as in `dump`.
+
 .. function:: load(stream)
 
    Parse the given *stream*, interpreting it as a JSON string and
diff --git a/docs/library/machine.I2C.rst b/docs/library/machine.I2C.rst
index f9b951564..f46d64ef5 100644
--- a/docs/library/machine.I2C.rst
+++ b/docs/library/machine.I2C.rst
@@ -28,15 +28,15 @@ Example usage::
                                     # depending on the port, extra parameters may be required
                                     # to select the peripheral and/or pins to use
 
-    i2c.scan()                      # scan for slaves, returning a list of 7-bit addresses
+    i2c.scan()                      # scan for peripherals, returning a list of 7-bit addresses
 
-    i2c.writeto(42, b'123')         # write 3 bytes to slave with 7-bit address 42
-    i2c.readfrom(42, 4)             # read 4 bytes from slave with 7-bit address 42
+    i2c.writeto(42, b'123')         # write 3 bytes to peripheral with 7-bit address 42
+    i2c.readfrom(42, 4)             # read 4 bytes from peripheral with 7-bit address 42
 
-    i2c.readfrom_mem(42, 8, 3)      # read 3 bytes from memory of slave 42,
-                                    #   starting at memory-address 8 in the slave
-    i2c.writeto_mem(42, 2, b'\x10') # write 1 byte to memory of slave 42
-                                    #   starting at address 2 in the slave
+    i2c.readfrom_mem(42, 8, 3)      # read 3 bytes from memory of peripheral 42,
+                                    #   starting at memory-address 8 in the peripheral
+    i2c.writeto_mem(42, 2, b'\x10') # write 1 byte to memory of peripheral 42
+                                    #   starting at address 2 in the peripheral
 
 Constructors
 ------------
@@ -95,7 +95,7 @@ General Methods
 Primitive I2C operations
 ------------------------
 
-The following methods implement the primitive I2C master bus operations and can
+The following methods implement the primitive I2C controller bus operations and can
 be combined to make any I2C transaction.  They are provided if you need more
 control over the bus, otherwise the standard methods (see below) can be used.
 
@@ -115,7 +115,7 @@ These methods are only available on the `machine.SoftI2C` class.
    read is the length of *buf*.  An ACK will be sent on the bus after
    receiving all but the last byte.  After the last byte is received, if *nack*
    is true then a NACK will be sent, otherwise an ACK will be sent (and in this
-   case the slave assumes more bytes are going to be read in a later call).
+   case the peripheral assumes more bytes are going to be read in a later call).
 
 .. method:: I2C.write(buf)
 
@@ -126,18 +126,18 @@ These methods are only available on the `machine.SoftI2C` class.
 Standard bus operations
 -----------------------
 
-The following methods implement the standard I2C master read and write
-operations that target a given slave device.
+The following methods implement the standard I2C controller read and write
+operations that target a given peripheral device.
 
 .. method:: I2C.readfrom(addr, nbytes, stop=True, /)
 
-   Read *nbytes* from the slave specified by *addr*.
+   Read *nbytes* from the peripheral specified by *addr*.
    If *stop* is true then a STOP condition is generated at the end of the transfer.
    Returns a `bytes` object with the data read.
 
 .. method:: I2C.readfrom_into(addr, buf, stop=True, /)
 
-   Read into *buf* from the slave specified by *addr*.
+   Read into *buf* from the peripheral specified by *addr*.
    The number of bytes read will be the length of *buf*.
    If *stop* is true then a STOP condition is generated at the end of the transfer.
 
@@ -145,7 +145,7 @@ operations that target a given slave device.
 
 .. method:: I2C.writeto(addr, buf, stop=True, /)
 
-   Write the bytes from *buf* to the slave specified by *addr*.  If a
+   Write the bytes from *buf* to the peripheral specified by *addr*.  If a
    NACK is received following the write of a byte from *buf* then the
    remaining bytes are not sent.  If *stop* is true then a STOP condition is
    generated at the end of the transfer, even if a NACK is received.
@@ -153,7 +153,7 @@ operations that target a given slave device.
 
 .. method:: I2C.writevto(addr, vector, stop=True, /)
 
-   Write the bytes contained in *vector* to the slave specified by *addr*.
+   Write the bytes contained in *vector* to the peripheral specified by *addr*.
    *vector* should be a tuple or list of objects with the buffer protocol.
    The *addr* is sent once and then the bytes from each object in *vector*
    are written out sequentially.  The objects in *vector* may be zero bytes
@@ -170,19 +170,19 @@ Memory operations
 
 Some I2C devices act as a memory device (or set of registers) that can be read
 from and written to.  In this case there are two addresses associated with an
-I2C transaction: the slave address and the memory address.  The following
+I2C transaction: the peripheral address and the memory address.  The following
 methods are convenience functions to communicate with such devices.
 
 .. method:: I2C.readfrom_mem(addr, memaddr, nbytes, *, addrsize=8)
 
-   Read *nbytes* from the slave specified by *addr* starting from the memory
+   Read *nbytes* from the peripheral specified by *addr* starting from the memory
    address specified by *memaddr*.
    The argument *addrsize* specifies the address size in bits.
    Returns a `bytes` object with the data read.
 
 .. method:: I2C.readfrom_mem_into(addr, memaddr, buf, *, addrsize=8)
 
-   Read into *buf* from the slave specified by *addr* starting from the
+   Read into *buf* from the peripheral specified by *addr* starting from the
    memory address specified by *memaddr*.  The number of bytes read is the
    length of *buf*.
    The argument *addrsize* specifies the address size in bits (on ESP8266
@@ -192,7 +192,7 @@ methods are convenience functions to communicate with such devices.
 
 .. method:: I2C.writeto_mem(addr, memaddr, buf, *, addrsize=8)
 
-   Write *buf* to the slave specified by *addr* starting from the
+   Write *buf* to the peripheral specified by *addr* starting from the
    memory address specified by *memaddr*.
    The argument *addrsize* specifies the address size in bits (on ESP8266
    this argument is not recognised and the address size is always 8 bits).
diff --git a/docs/library/machine.I2S.rst b/docs/library/machine.I2S.rst
new file mode 100644
index 000000000..45877a5ae
--- /dev/null
+++ b/docs/library/machine.I2S.rst
@@ -0,0 +1,162 @@
+.. currentmodule:: machine
+.. _machine.I2S:
+
+class I2S -- Inter-IC Sound bus protocol
+========================================
+
+I2S is a synchronous serial protocol used to connect digital audio devices. 
+At the physical level, a bus consists of 3 lines: SCK, WS, SD.
+The I2S class supports controller operation.  Peripheral operation is not supported.
+
+The I2S class is currently available as a Technical Preview.  During the preview period, feedback from 
+users is encouraged.  Based on this feedback, the I2S class API and implementation may be changed.
+
+I2S objects can be created and initialized using::
+
+    from machine import I2S
+    from machine import Pin
+    
+    # ESP32
+    sck_pin = Pin(14)   # Serial clock output
+    ws_pin = Pin(13)    # Word clock output
+    sd_pin = Pin(12)    # Serial data output
+    
+    or
+    
+    # PyBoards
+    sck_pin = Pin("Y6")   # Serial clock output
+    ws_pin = Pin("Y5")    # Word clock output
+    sd_pin = Pin("Y8")    # Serial data output
+    
+    audio_out = I2S(2, 
+                    sck=sck_pin, ws=ws_pin, sd=sd_pin,
+                    mode=I2S.TX, 
+                    bits=16,                       
+                    format=I2S.MONO,
+                    rate=44100, 
+                    ibuf=20000)
+                   
+    audio_in = I2S(2, 
+                   sck=sck_pin, ws=ws_pin, sd=sd_pin,
+                   mode=I2S.RX, 
+                   bits=32,                       
+                   format=I2S.STEREO,
+                   rate=22050, 
+                   ibuf=20000)
+                    
+3 modes of operation are supported:
+ - blocking 
+ - non-blocking 
+ - uasyncio
+  
+blocking::
+ 
+   num_written = audio_out.write(buf) # blocks until buf emptied
+
+   num_read = audio_in.readinto(buf) # blocks until buf filled
+   
+non-blocking::
+ 
+   audio_out.irq(i2s_callback)         # i2s_callback is called when buf is emptied
+   num_written = audio_out.write(buf)  # returns immediately
+        
+   audio_in.irq(i2s_callback)          # i2s_callback is called when buf is filled
+   num_read = audio_in.readinto(buf)   # returns immediately    
+ 
+uasyncio::
+ 
+   swriter = uasyncio.StreamWriter(audio_out)
+   swriter.write(buf)
+   await swriter.drain()
+   
+   sreader = uasyncio.StreamReader(audio_in)
+   num_read = await sreader.readinto(buf)
+ 
+Constructor
+-----------
+
+.. class:: I2S(id, *, sck, ws, sd, mode, bits, format, rate, ibuf)
+
+   Construct an I2S object of the given id:
+   
+   - ``id`` identifies a particular I2S bus.  
+
+   ``id`` is board and port specific:
+ 
+     - PYBv1.0/v1.1: has one I2S bus with id=2.
+     - PYBD-SFxW: has two I2S buses with id=1 and id=2. 
+     - ESP32: has two I2S buses with id=0 and id=1. 
+   
+   Keyword-only parameters that are supported on all ports:
+    
+     - ``sck`` is a pin object for the serial clock line
+     - ``ws`` is a pin object for the word select line
+     - ``sd`` is a pin object for the serial data line
+     - ``mode`` specifies receive or transmit
+     - ``bits`` specifies sample size (bits), 16 or 32
+     - ``format`` specifies channel format, STEREO or MONO
+     - ``rate`` specifies audio sampling rate (samples/s)
+     - ``ibuf`` specifies internal buffer length (bytes)
+     
+   For all ports, DMA runs continuously in the background and allows user applications to perform other operations while 
+   sample data is transfered between the internal buffer and the I2S peripheral unit. 
+   Increasing the size of the internal buffer has the potential to increase the time that user applications can perform non-I2S operations
+   before underflow (e.g. ``write`` method) or overflow (e.g. ``readinto`` method).
+
+Methods
+-------
+
+.. method:: I2S.init(sck, ...)
+
+  see Constructor for argument descriptions
+     
+.. method:: I2S.deinit()
+
+  Deinitialize the I2S bus
+  
+.. method::  I2S.readinto(buf)
+
+  Read audio samples into the buffer specified by ``buf``.  ``buf`` must support the buffer protocol, such as bytearray or array. 
+  "buf" byte ordering is little-endian.  For Stereo format, left channel sample precedes right channel sample. For Mono format, 
+  the left channel sample data is used.
+  Returns number of bytes read 
+  
+.. method::  I2S.write(buf)
+
+  Write audio samples contained in ``buf``. ``buf`` must support the buffer protocol, such as bytearray or array.
+  "buf" byte ordering is little-endian.  For Stereo format, left channel sample precedes right channel sample. For Mono format, 
+  the sample data is written to both the right and left channels.
+  Returns number of bytes written 
+  
+.. method::  I2S.irq(handler)
+
+  Set a callback. ``handler`` is called when ``buf`` is emptied (``write`` method) or becomes full (``readinto`` method).  
+  Setting a callback changes the ``write`` and ``readinto`` methods to non-blocking operation.
+  ``handler`` is called in the context of the MicroPython scheduler.
+  
+.. staticmethod::  I2S.shift(buf, bits, shift)
+
+  bitwise shift of all samples contained in ``buf``. ``bits`` specifies sample size in bits. ``shift`` specifies the number of bits to shift each sample. 
+  Positive for left shift, negative for right shift. 
+  Typically used for volume control.  Each bit shift changes sample volume by 6dB.
+  
+Constants
+---------
+
+.. data:: I2S.RX
+
+   for initialising the I2S bus ``mode`` to receive
+
+.. data:: I2S.TX
+
+   for initialising the I2S bus ``mode`` to transmit
+
+.. data:: I2S.STEREO
+
+   for initialising the I2S bus ``format`` to stereo
+
+.. data:: I2S.MONO
+
+   for initialising the I2S bus ``format`` to mono
+
+
diff --git a/docs/library/machine.SDCard.rst b/docs/library/machine.SDCard.rst
index b1cf42ec0..96fb5b01c 100644
--- a/docs/library/machine.SDCard.rst
+++ b/docs/library/machine.SDCard.rst
@@ -27,10 +27,10 @@ vary from platform to platform.
 
     This class provides access to SD or MMC storage cards using either
     a dedicated SD/MMC interface hardware or through an SPI channel.
-    The class implements the block protocol defined by :class:`uos.AbstractBlockDev`.
+    The class implements the block protocol defined by :class:`os.AbstractBlockDev`.
     This allows the mounting of an SD card to be as simple as::
 
-      uos.mount(machine.SDCard(), "/sd")
+      os.mount(machine.SDCard(), "/sd")
 
     The constructor takes the following parameters:
 
diff --git a/docs/library/machine.SPI.rst b/docs/library/machine.SPI.rst
index 7565241eb..46ac2ec74 100644
--- a/docs/library/machine.SPI.rst
+++ b/docs/library/machine.SPI.rst
@@ -1,14 +1,14 @@
 .. currentmodule:: machine
 .. _machine.SPI:
 
-class SPI -- a Serial Peripheral Interface bus protocol (master side)
-=====================================================================
+class SPI -- a Serial Peripheral Interface bus protocol (controller side)
+=========================================================================
 
-SPI is a synchronous serial protocol that is driven by a master. At the
+SPI is a synchronous serial protocol that is driven by a controller. At the
 physical level, a bus consists of 3 lines: SCK, MOSI, MISO. Multiple devices
 can share the same bus. Each device should have a separate, 4th signal,
-SS (Slave Select), to select a particular device on a bus with which
-communication takes place. Management of an SS signal should happen in
+CS (Chip Select), to select a particular device on a bus with which
+communication takes place. Management of a CS signal should happen in
 user code (via machine.Pin class).
 
 Both hardware and software SPI implementations exist via the
@@ -102,9 +102,9 @@ Methods
 Constants
 ---------
 
-.. data:: SPI.MASTER
+.. data:: SPI.CONTROLLER
 
-   for initialising the SPI bus to master; this is only used for the WiPy
+   for initialising the SPI bus to controller; this is only used for the WiPy
 
 .. data:: SPI.MSB
 
diff --git a/docs/library/machine.UART.rst b/docs/library/machine.UART.rst
index 957d58ca1..2eb2e20cb 100644
--- a/docs/library/machine.UART.rst
+++ b/docs/library/machine.UART.rst
@@ -56,11 +56,22 @@ Methods
 
      - *tx* specifies the TX pin to use.
      - *rx* specifies the RX pin to use.
+     - *rts* specifies the RTS (output) pin to use for hardware receive flow control.
+     - *cts* specifies the CTS (input) pin to use for hardware transmit flow control.
      - *txbuf* specifies the length in characters of the TX buffer.
      - *rxbuf* specifies the length in characters of the RX buffer.
      - *timeout* specifies the time to wait for the first character (in ms).
      - *timeout_char* specifies the time to wait between characters (in ms).
      - *invert* specifies which lines to invert.
+     - *flow* specifies which hardware flow control signals to use. The value
+       is a bitmask. 
+
+         - ``0`` will ignore hardware flow control signals.
+         - ``UART.RTS`` will enable receive flow control by using the RTS output pin to
+           signal if the receive FIFO has sufficient space to accept more data.
+         - ``UART.CTS`` will enable transmit flow control by pausing transmission when the
+           CTS input pin signals that the receiver is running low on buffer space.
+         - ``UART.RTS | UART.CTS`` will enable both, for full hardware flow control.
 
    On the WiPy only the following keyword-only parameter is supported:
 
diff --git a/docs/library/machine.rst b/docs/library/machine.rst
index 0a1c1c953..c2a6b3900 100644
--- a/docs/library/machine.rst
+++ b/docs/library/machine.rst
@@ -137,6 +137,28 @@ Miscellaneous functions
    above. The timeout is the same for both cases and given by *timeout_us* (which
    is in microseconds).
 
+.. function:: bitstream(pin, encoding, timing, data, /)
+
+   Transmits *data* by bit-banging the specified *pin*. The *encoding* argument
+   specifies how the bits are encoded, and *timing* is an encoding-specific timing
+   specification.
+
+   The supported encodings are:
+
+     - ``0`` for "high low" pulse duration modulation. This will transmit 0 and
+       1 bits as timed pulses, starting with the most significant bit.
+       The *timing* must be a four-tuple of nanoseconds in the format
+       ``(high_time_0, low_time_0, high_time_1, low_time_1)``. For example,
+       ``(400, 850, 800, 450)`` is the timing specification for WS2812 RGB LEDs
+       at 800kHz.
+
+   The accuracy of the timing varies between ports. On Cortex M0 at 48MHz, it is
+   at best +/- 120ns, however on faster MCUs (ESP8266, ESP32, STM32, Pyboard), it
+   will be closer to +/-30ns.
+
+   .. note:: For controlling WS2812 / NeoPixel strips, see the :mod:`neopixel`
+      module for a higher-level API.
+
 .. function:: rng()
 
    Return a 24-bit software generated random number.
@@ -181,6 +203,7 @@ Classes
    machine.UART.rst
    machine.SPI.rst
    machine.I2C.rst
+   machine.I2S.rst   
    machine.RTC.rst
    machine.Timer.rst
    machine.WDT.rst
diff --git a/docs/library/neopixel.rst b/docs/library/neopixel.rst
new file mode 100644
index 000000000..1b37f088b
--- /dev/null
+++ b/docs/library/neopixel.rst
@@ -0,0 +1,73 @@
+:mod:`neopixel` --- control of WS2812 / NeoPixel LEDs
+=====================================================
+
+.. module:: neopixel
+   :synopsis: control of WS2812 / NeoPixel LEDs
+
+This module provides a driver for WS2818 / NeoPixel LEDs.
+
+.. note:: This module is only included by default on the ESP8266 and ESP32
+   ports. On STM32 / Pyboard, you can `download the module
+   <https://github.com/micropython/micropython/blob/master/drivers/neopixel/neopixel.py>`_
+   and copy it to the filesystem.
+
+class NeoPixel
+--------------
+
+This class stores pixel data for a WS2812 LED strip connected to a pin. The
+application should set pixel data and then call :meth:`NeoPixel.write`
+when it is ready to update the strip.
+
+For example::
+
+    import neopixel
+
+    # 32 LED strip connected to X8.
+    p = machine.Pin.board.X8
+    n = neopixel.NeoPixel(p, 32)
+
+    # Draw a red gradient.
+    for i in range(32):
+        n[i] = (i * 8, 0, 0)
+
+    # Update the strip.
+    n.write()
+
+Constructors
+------------
+
+.. class:: NeoPixel(pin, n, *, bpp=3, timing=1)
+
+    Construct an NeoPixel object.  The parameters are:
+
+        - *pin* is a machine.Pin instance.
+        - *n* is the number of LEDs in the strip.
+        - *bpp* is 3 for RGB LEDs, and 4 for RGBW LEDs.
+        - *timing* is 0 for 400KHz, and 1 for 800kHz LEDs (most are 800kHz).
+
+Pixel access methods
+--------------------
+
+.. method:: NeoPixel.fill(pixel)
+
+    Sets the value of all pixels to the specified *pixel* value (i.e. an
+    RGB/RGBW tuple).
+
+.. method:: NeoPixel.__len__()
+
+    Returns the number of LEDs in the strip.
+
+.. method:: NeoPixel.__setitem__(index, val)
+
+    Set the pixel at *index* to the value, which is an RGB/RGBW tuple.
+
+.. method:: NeoPixel.__getitem__(index)
+
+    Returns the pixel at *index* as an RGB/RGBW tuple.
+
+Output methods
+--------------
+
+.. method:: NeoPixel.write()
+
+    Writes the current pixel data to the strip.
diff --git a/docs/library/network.WLAN.rst b/docs/library/network.WLAN.rst
index 88bd3a370..72091d0ea 100644
--- a/docs/library/network.WLAN.rst
+++ b/docs/library/network.WLAN.rst
@@ -46,6 +46,8 @@ Methods
 .. method:: WLAN.scan()
 
     Scan for the available wireless networks.
+    Hidden networks -- where the SSID is not broadcast -- will also be scanned
+    if the WLAN interface allows it.
 
     Scanning is only possible on STA interface. Returns list of tuples with
     the information about WiFi access points:
@@ -53,7 +55,7 @@ Methods
         (ssid, bssid, channel, RSSI, authmode, hidden)
 
     *bssid* is hardware address of an access point, in binary form, returned as
-    bytes object. You can use `ubinascii.hexlify()` to convert it to ASCII form.
+    bytes object. You can use `binascii.hexlify()` to convert it to ASCII form.
 
     There are five values for authmode:
 
diff --git a/docs/library/network.rst b/docs/library/network.rst
index a20eb2ebf..1bd7e303b 100644
--- a/docs/library/network.rst
+++ b/docs/library/network.rst
@@ -9,7 +9,7 @@ This module provides network drivers and routing configuration. To use this
 module, a MicroPython variant/build with network capabilities must be installed.
 Network drivers for specific hardware are available within this module and are
 used to configure hardware network interface(s). Network services provided
-by configured interfaces are then available for use via the :mod:`usocket`
+by configured interfaces are then available for use via the :mod:`socket`
 module.
 
 For example::
@@ -17,17 +17,17 @@ For example::
     # connect/ show IP config a specific network interface
     # see below for examples of specific drivers
     import network
-    import utime
+    import time
     nic = network.Driver(...)
     if not nic.isconnected():
         nic.connect()
         print("Waiting for connection...")
         while not nic.isconnected():
-            utime.sleep(1)
+            time.sleep(1)
     print(nic.ifconfig())
 
-    # now use usocket as usual
-    import usocket as socket
+    # now use socket as usual
+    import socket
     addr = socket.getaddrinfo('micropython.org', 80)[0][-1]
     s = socket.socket()
     s.connect(addr)
diff --git a/docs/library/uos.rst b/docs/library/os.rst
similarity index 97%
rename from docs/library/uos.rst
rename to docs/library/os.rst
index edc94556b..a1eae4f24 100644
--- a/docs/library/uos.rst
+++ b/docs/library/os.rst
@@ -1,12 +1,12 @@
-:mod:`uos` -- basic "operating system" services
-===============================================
+:mod:`os` -- basic "operating system" services
+==============================================
 
-.. module:: uos
+.. module:: os
    :synopsis: basic "operating system" services
 
 |see_cpython_module| :mod:`python:os`.
 
-The ``uos`` module contains functions for filesystem access and mounting,
+The ``os`` module contains functions for filesystem access and mounting,
 terminal redirection and duplication, and the ``uname`` and ``urandom``
 functions.
 
@@ -116,7 +116,7 @@ Terminal redirection and duplication
 
    Duplicate or switch the MicroPython terminal (the REPL) on the given `stream`-like
    object. The *stream_object* argument must be a native stream object, or derive
-   from ``uio.IOBase`` and implement the ``readinto()`` and
+   from ``io.IOBase`` and implement the ``readinto()`` and
    ``write()`` methods.  The stream should be in non-blocking mode and
    ``readinto()`` should return ``None`` if there is no data available for reading.
 
@@ -207,7 +207,7 @@ represented by VFS classes.
     otherwise the timestamps will remain untouched.  Littlefs v2 filesystems without
     timestamps will work without reformatting and timestamps will be added
     transparently to existing files once they are opened for writing.  When *mtime*
-    is enabled `uos.stat` on files without timestamps will return 0 for the timestamp.
+    is enabled `os.stat` on files without timestamps will return 0 for the timestamp.
 
     See :ref:`filesystem` for more information.
 
@@ -234,7 +234,7 @@ but an actual block device class must implement the methods described below.
 
 A concrete implementation of this class will usually allow access to the
 memory-like functionality of a piece of hardware (like flash memory). A block
-device can be formatted to any supported filesystem and mounted using ``uos``
+device can be formatted to any supported filesystem and mounted using ``os``
 methods.
 
 See :ref:`filesystem` for example implementations of block devices using the
diff --git a/docs/library/pyb.Flash.rst b/docs/library/pyb.Flash.rst
index 4b0c2ce2a..01b3a0ac9 100644
--- a/docs/library/pyb.Flash.rst
+++ b/docs/library/pyb.Flash.rst
@@ -43,7 +43,7 @@ Methods
 
     These methods implement the simple and :ref:`extended
     <block-device-interface>` block protocol defined by
-    :class:`uos.AbstractBlockDev`.
+    :class:`os.AbstractBlockDev`.
 
 Hardware Note
 -------------
diff --git a/docs/library/pyb.I2C.rst b/docs/library/pyb.I2C.rst
index 56b036e07..f60b50686 100644
--- a/docs/library/pyb.I2C.rst
+++ b/docs/library/pyb.I2C.rst
@@ -14,11 +14,11 @@ Example::
 
     from pyb import I2C
 
-    i2c = I2C(1)                         # create on bus 1
-    i2c = I2C(1, I2C.MASTER)             # create and init as a master
-    i2c.init(I2C.MASTER, baudrate=20000) # init as a master
-    i2c.init(I2C.SLAVE, addr=0x42)       # init as a slave with given address
-    i2c.deinit()                         # turn off the peripheral
+    i2c = I2C(1)                             # create on bus 1
+    i2c = I2C(1, I2C.CONTROLLER)             # create and init as a controller
+    i2c.init(I2C.CONTROLLER, baudrate=20000) # init as a controller
+    i2c.init(I2C.PERIPHERAL, addr=0x42)      # init as a peripheral with given address
+    i2c.deinit()                             # turn off the I2C unit
 
 Printing the i2c object gives you information about its configuration.
 
@@ -37,21 +37,21 @@ You can specify a timeout (in ms)::
 
     i2c.send(b'123', timeout=2000)   # timeout after 2 seconds
 
-A master must specify the recipient's address::
+A controller must specify the recipient's address::
 
-    i2c.init(I2C.MASTER)
-    i2c.send('123', 0x42)        # send 3 bytes to slave with address 0x42
+    i2c.init(I2C.CONTROLLER)
+    i2c.send('123', 0x42)        # send 3 bytes to peripheral with address 0x42
     i2c.send(b'456', addr=0x42)  # keyword for address
 
 Master also has other methods::
 
-    i2c.is_ready(0x42)           # check if slave 0x42 is ready
-    i2c.scan()                   # scan for slaves on the bus, returning
+    i2c.is_ready(0x42)           # check if peripheral 0x42 is ready
+    i2c.scan()                   # scan for peripherals on the bus, returning
                                  #   a list of valid addresses
-    i2c.mem_read(3, 0x42, 2)     # read 3 bytes from memory of slave 0x42,
-                                 #   starting at address 2 in the slave
-    i2c.mem_write('abc', 0x42, 2, timeout=1000) # write 'abc' (3 bytes) to memory of slave 0x42
-                                                # starting at address 2 in the slave, timeout after 1 second
+    i2c.mem_read(3, 0x42, 2)     # read 3 bytes from memory of peripheral 0x42,
+                                 #   starting at address 2 in the peripheral
+    i2c.mem_write('abc', 0x42, 2, timeout=1000) # write 'abc' (3 bytes) to memory of peripheral 0x42
+                                                # starting at address 2 in the peripheral, timeout after 1 second
 
 Constructors
 ------------
@@ -88,9 +88,9 @@ Methods
 
   Initialise the I2C bus with the given parameters:
 
-     - ``mode`` must be either ``I2C.MASTER`` or ``I2C.SLAVE``
-     - ``addr`` is the 7-bit address (only sensible for a slave)
-     - ``baudrate`` is the SCL clock rate (only sensible for a master)
+     - ``mode`` must be either ``I2C.CONTROLLER`` or ``I2C.PERIPHERAL``
+     - ``addr`` is the 7-bit address (only sensible for a peripheral)
+     - ``baudrate`` is the SCL clock rate (only sensible for a controller)
      - ``gencall`` is whether to support general call mode
      - ``dma`` is whether to allow the use of DMA for the I2C transfers (note
        that DMA transfers have more precise timing but currently do not handle bus
@@ -98,7 +98,7 @@ Methods
 
 .. method:: I2C.is_ready(addr)
 
-   Check if an I2C device responds to the given address.  Only valid when in master mode.
+   Check if an I2C device responds to the given address.  Only valid when in controller mode.
 
 .. method:: I2C.mem_read(data, addr, memaddr, *, timeout=5000, addr_size=8)
 
@@ -111,7 +111,7 @@ Methods
      - ``addr_size`` selects width of memaddr: 8 or 16 bits
 
    Returns the read data.
-   This is only valid in master mode.
+   This is only valid in controller mode.
 
 .. method:: I2C.mem_write(data, addr, memaddr, *, timeout=5000, addr_size=8)
 
@@ -124,7 +124,7 @@ Methods
      - ``addr_size`` selects width of memaddr: 8 or 16 bits
 
    Returns ``None``.
-   This is only valid in master mode.
+   This is only valid in controller mode.
 
 .. method:: I2C.recv(recv, addr=0x00, *, timeout=5000)
 
@@ -132,7 +132,7 @@ Methods
 
      - ``recv`` can be an integer, which is the number of bytes to receive,
        or a mutable buffer, which will be filled with received bytes
-     - ``addr`` is the address to receive from (only required in master mode)
+     - ``addr`` is the address to receive from (only required in controller mode)
      - ``timeout`` is the timeout in milliseconds to wait for the receive
 
    Return value: if ``recv`` is an integer then a new buffer of the bytes received,
@@ -143,7 +143,7 @@ Methods
    Send data on the bus:
 
      - ``send`` is the data to send (an integer to send, or a buffer object)
-     - ``addr`` is the address to send to (only required in master mode)
+     - ``addr`` is the address to send to (only required in controller mode)
      - ``timeout`` is the timeout in milliseconds to wait for the send
 
    Return value: ``None``.
@@ -151,15 +151,15 @@ Methods
 .. method:: I2C.scan()
 
    Scan all I2C addresses from 0x01 to 0x7f and return a list of those that respond.
-   Only valid when in master mode.
+   Only valid when in controller mode.
 
 Constants
 ---------
 
-.. data:: I2C.MASTER
+.. data:: I2C.CONTROLLER
 
-   for initialising the bus to master mode
+   for initialising the bus to controller mode
 
-.. data:: I2C.SLAVE
+.. data:: I2C.PERIPHERAL
 
-   for initialising the bus to slave mode
+   for initialising the bus to peripheral mode
diff --git a/docs/library/pyb.SPI.rst b/docs/library/pyb.SPI.rst
index c76b16789..1bdb73a5d 100644
--- a/docs/library/pyb.SPI.rst
+++ b/docs/library/pyb.SPI.rst
@@ -1,19 +1,19 @@
 .. currentmodule:: pyb
 .. _pyb.SPI:
 
-class SPI -- a master-driven serial protocol
-============================================
+class SPI -- a controller-driven serial protocol
+================================================
 
-SPI is a serial protocol that is driven by a master.  At the physical level
+SPI is a serial protocol that is driven by a controller.  At the physical level
 there are 3 lines: SCK, MOSI, MISO.
 
 See usage model of I2C; SPI is very similar.  Main difference is
 parameters to init the SPI bus::
 
     from pyb import SPI
-    spi = SPI(1, SPI.MASTER, baudrate=600000, polarity=1, phase=0, crc=0x7)
+    spi = SPI(1, SPI.CONTROLLER, baudrate=600000, polarity=1, phase=0, crc=0x7)
 
-Only required parameter is mode, SPI.MASTER or SPI.SLAVE.  Polarity can be
+Only required parameter is mode, SPI.CONTROLLER or SPI.PERIPHERAL.  Polarity can be
 0 or 1, and is the level the idle clock line sits at.  Phase can be 0 or 1
 to sample data on the first or second clock edge respectively.  Crc can be
 None for no CRC, or a polynomial specifier.
@@ -55,8 +55,8 @@ Methods
 
    Initialise the SPI bus with the given parameters:
 
-     - ``mode`` must be either ``SPI.MASTER`` or ``SPI.SLAVE``.
-     - ``baudrate`` is the SCK clock rate (only sensible for a master).
+     - ``mode`` must be either ``SPI.CONTROLLER`` or ``SPI.PERIPHERAL``.
+     - ``baudrate`` is the SCK clock rate (only sensible for a controller).
      - ``prescaler`` is the prescaler to use to derive SCK from the APB bus frequency;
        use of ``prescaler`` overrides ``baudrate``.
      - ``polarity`` can be 0 or 1, and is the level the idle clock line sits at.
@@ -112,10 +112,10 @@ Methods
 Constants
 ---------
 
-.. data:: SPI.MASTER
-.. data:: SPI.SLAVE
+.. data:: SPI.CONTROLLER
+.. data:: SPI.PERIPHERAL
 
-   for initialising the SPI bus to master or slave mode
+   for initialising the SPI bus to controller or peripheral mode
 
 .. data:: SPI.LSB
 .. data:: SPI.MSB
diff --git a/docs/library/pyb.rst b/docs/library/pyb.rst
index 321be3c52..880d68c53 100644
--- a/docs/library/pyb.rst
+++ b/docs/library/pyb.rst
@@ -213,11 +213,11 @@ Miscellaneous functions
 .. function:: mount(device, mountpoint, *, readonly=False, mkfs=False)
 
    .. note:: This function is deprecated. Mounting and unmounting devices should
-      be performed by :meth:`uos.mount` and :meth:`uos.umount` instead.
+      be performed by :meth:`os.mount` and :meth:`os.umount` instead.
 
    Mount a block device and make it available as part of the filesystem.
    ``device`` must be an object that provides the block protocol. (The
-   following is also deprecated. See :class:`uos.AbstractBlockDev` for the
+   following is also deprecated. See :class:`os.AbstractBlockDev` for the
    correct way to create a block device.)
 
     - ``readblocks(self, blocknum, buf)``
diff --git a/docs/library/ure.rst b/docs/library/re.rst
similarity index 96%
rename from docs/library/ure.rst
rename to docs/library/re.rst
index e94d28617..19b15d2d2 100644
--- a/docs/library/ure.rst
+++ b/docs/library/re.rst
@@ -1,7 +1,7 @@
-:mod:`ure` -- simple regular expressions
-========================================
+:mod:`re` -- simple regular expressions
+=======================================
 
-.. module:: ure
+.. module:: re
    :synopsis: regular expressions
 
 |see_cpython_module| :mod:`python:re`.
@@ -95,11 +95,11 @@ Supported operators and special sequences are:
 
 Example::
 
-    import ure
+    import re
 
-    # As ure doesn't support escapes itself, use of r"" strings is not
+    # As re doesn't support escapes itself, use of r"" strings is not
     # recommended.
-    regex = ure.compile("[\r\n]")
+    regex = re.compile("[\r\n]")
 
     regex.split("line1\rline2\nline3\r\n")
 
@@ -152,7 +152,7 @@ Regex objects
 -------------
 
 Compiled regular expression. Instances of this class are created using
-`ure.compile()`.
+`re.compile()`.
 
 .. method:: regex.match(string)
             regex.search(string)
diff --git a/docs/library/rp2.Flash.rst b/docs/library/rp2.Flash.rst
index 3b423adfd..1e94cf519 100644
--- a/docs/library/rp2.Flash.rst
+++ b/docs/library/rp2.Flash.rst
@@ -32,5 +32,5 @@ Methods
 
     These methods implement the simple and extended
     :ref:`block protocol <block-device-interface>` defined by
-    :class:`uos.AbstractBlockDev`.
+    :class:`os.AbstractBlockDev`.
 
diff --git a/docs/library/uselect.rst b/docs/library/select.rst
similarity index 84%
rename from docs/library/uselect.rst
rename to docs/library/select.rst
index 76202739c..57adbb49a 100644
--- a/docs/library/uselect.rst
+++ b/docs/library/select.rst
@@ -1,7 +1,7 @@
-:mod:`uselect` -- wait for events on a set of streams
-========================================================================
+:mod:`select` -- wait for events on a set of streams
+====================================================
 
-.. module:: uselect
+.. module:: select
    :synopsis: wait for events on a set of streams
 
 |see_cpython_module| :mod:`python:select`.
@@ -35,15 +35,15 @@ Methods
 
    Register `stream` *obj* for polling. *eventmask* is logical OR of:
 
-   * ``uselect.POLLIN``  - data available for reading
-   * ``uselect.POLLOUT`` - more data can be written
+   * ``select.POLLIN``  - data available for reading
+   * ``select.POLLOUT`` - more data can be written
 
-   Note that flags like ``uselect.POLLHUP`` and ``uselect.POLLERR`` are
+   Note that flags like ``select.POLLHUP`` and ``select.POLLERR`` are
    *not* valid as input eventmask (these are unsolicited events which
    will be returned from `poll()` regardless of whether they are asked
    for). This semantics is per POSIX.
 
-   *eventmask* defaults to ``uselect.POLLIN | uselect.POLLOUT``.
+   *eventmask* defaults to ``select.POLLIN | select.POLLOUT``.
 
    It is OK to call this function multiple times for the same *obj*.
    Successive calls will update *obj*'s eventmask to the value of
@@ -67,8 +67,8 @@ Methods
    Returns list of (``obj``, ``event``, ...) tuples. There may be other elements in
    tuple, depending on a platform and version, so don't assume that its size is 2.
    The ``event`` element specifies which events happened with a stream and
-   is a combination of ``uselect.POLL*`` constants described above. Note that
-   flags ``uselect.POLLHUP`` and ``uselect.POLLERR`` can be returned at any time
+   is a combination of ``select.POLL*`` constants described above. Note that
+   flags ``select.POLLHUP`` and ``select.POLLERR`` can be returned at any time
    (even if were not asked for), and must be acted on accordingly (the
    corresponding stream unregistered from poll and likely closed), because
    otherwise all further invocations of `poll()` may return immediately with
diff --git a/docs/library/usocket.rst b/docs/library/socket.rst
similarity index 91%
rename from docs/library/usocket.rst
rename to docs/library/socket.rst
index 39b848e59..704b614ab 100644
--- a/docs/library/usocket.rst
+++ b/docs/library/socket.rst
@@ -1,8 +1,8 @@
-*******************************
-:mod:`usocket` -- socket module
-*******************************
+******************************
+:mod:`socket` -- socket module
+******************************
 
-.. module:: usocket
+.. module:: socket
    :synopsis: socket module
 
 |see_cpython_module| :mod:`python:socket`.
@@ -21,13 +21,13 @@ This module provides access to the BSD socket interface.
 Socket address format(s)
 ------------------------
 
-The native socket address format of the ``usocket`` module is an opaque data type
+The native socket address format of the ``socket`` module is an opaque data type
 returned by `getaddrinfo` function, which must be used to resolve textual address
 (including numeric addresses)::
 
-    sockaddr = usocket.getaddrinfo('www.micropython.org', 80)[0][-1]
+    sockaddr = socket.getaddrinfo('www.micropython.org', 80)[0][-1]
     # You must use getaddrinfo() even for numeric addresses
-    sockaddr = usocket.getaddrinfo('127.0.0.1', 80)[0][-1]
+    sockaddr = socket.getaddrinfo('127.0.0.1', 80)[0][-1]
     # Now you can use that address
     sock.connect(addr)
 
@@ -35,7 +35,7 @@ Using `getaddrinfo` is the most efficient (both in terms of memory and processin
 power) and portable way to work with addresses.
 
 However, ``socket`` module (note the difference with native MicroPython
-``usocket`` module described here) provides CPython-compatible way to specify
+``socket`` module described here) provides CPython-compatible way to specify
 addresses using tuples, as described below. Note that depending on a
 :term:`MicroPython port`, ``socket`` module can be builtin or need to be
 installed from `micropython-lib` (as in the case of :term:`MicroPython Unix port`),
@@ -54,13 +54,13 @@ Tuple address format for ``socket`` module:
   dot-notation numeric IPv4 address, e.g. ``"8.8.8.8"``, and *port* is and
   integer port number in the range 1-65535. Note the domain names are not
   accepted as *ipv4_address*, they should be resolved first using
-  `usocket.getaddrinfo()`.
+  `socket.getaddrinfo()`.
 * IPv6: *(ipv6_address, port, flowinfo, scopeid)*, where *ipv6_address*
   is a string with colon-notation numeric IPv6 address, e.g. ``"2001:db8::1"``,
   and *port* is an integer port number in the range 1-65535. *flowinfo*
   must be 0. *scopeid* is the interface scope identifier for link-local
   addresses. Note the domain names are not accepted as *ipv6_address*,
-  they should be resolved first using `usocket.getaddrinfo()`. Availability
+  they should be resolved first using `socket.getaddrinfo()`. Availability
   of IPv6 support depends on a :term:`MicroPython port`.
 
 Functions
@@ -94,17 +94,17 @@ Functions
 
    The following example shows how to connect to a given url::
 
-      s = usocket.socket()
+      s = socket.socket()
       # This assumes that if "type" is not specified, an address for
       # SOCK_STREAM will be returned, which may be not true
-      s.connect(usocket.getaddrinfo('www.micropython.org', 80)[0][-1])
+      s.connect(socket.getaddrinfo('www.micropython.org', 80)[0][-1])
 
    Recommended use of filtering params::
 
-      s = usocket.socket()
+      s = socket.socket()
       # Guaranteed to return an address which can be connect'ed to for
       # stream operation.
-      s.connect(usocket.getaddrinfo('www.micropython.org', 80, 0, SOCK_STREAM)[0][-1])
+      s.connect(socket.getaddrinfo('www.micropython.org', 80, 0, SOCK_STREAM)[0][-1])
 
    .. admonition:: Difference to CPython
       :class: attention
@@ -113,7 +113,7 @@ Functions
       of error in this function. MicroPython doesn't have ``socket.gaierror``
       and raises OSError directly. Note that error numbers of `getaddrinfo()`
       form a separate namespace and may not match error numbers from
-      the :mod:`uerrno` module. To distinguish `getaddrinfo()` errors, they are
+      the :mod:`errno` module. To distinguish `getaddrinfo()` errors, they are
       represented by negative numbers, whereas standard system errors are
       positive numbers (error numbers are accessible using ``e.args[0]`` property
       from an exception object). The use of negative values is a provisional
@@ -124,7 +124,7 @@ Functions
    Convert a binary network address *bin_addr* of the given address family *af*
    to a textual representation::
 
-        >>> usocket.inet_ntop(usocket.AF_INET, b"\x7f\0\0\1")
+        >>> socket.inet_ntop(socket.AF_INET, b"\x7f\0\0\1")
         '127.0.0.1'
 
 .. function:: inet_pton(af, txt_addr)
@@ -132,7 +132,7 @@ Functions
    Convert a textual network address *txt_addr* of the given address family *af*
    to a binary representation::
 
-        >>> usocket.inet_pton(usocket.AF_INET, "1.2.3.4")
+        >>> socket.inet_pton(socket.AF_INET, "1.2.3.4")
         b'\x01\x02\x03\x04'
 
 Constants
@@ -152,17 +152,17 @@ Constants
           IPPROTO_TCP
 
    IP protocol numbers. Availability depends on a particular :term:`MicroPython port`.
-   Note that you don't need to specify these in a call to `usocket.socket()`,
+   Note that you don't need to specify these in a call to `socket.socket()`,
    because `SOCK_STREAM` socket type automatically selects `IPPROTO_TCP`, and
    `SOCK_DGRAM` - `IPPROTO_UDP`. Thus, the only real use of these constants
    is as an argument to `setsockopt()`.
 
-.. data:: usocket.SOL_*
+.. data:: socket.SOL_*
 
    Socket option levels (an argument to `setsockopt()`). The exact
    inventory depends on a :term:`MicroPython port`.
 
-.. data:: usocket.SO_*
+.. data:: socket.SO_*
 
    Socket options (an argument to `setsockopt()`). The exact
    inventory depends on a :term:`MicroPython port`.
@@ -260,7 +260,7 @@ Methods
    is put in blocking mode.
 
    Not every :term:`MicroPython port` supports this method. A more portable and
-   generic solution is to use `uselect.poll` object. This allows to wait on
+   generic solution is to use `select.poll` object. This allows to wait on
    multiple objects at the same time (and not just on sockets, but on generic
    `stream` objects which support polling). Example::
 
@@ -269,8 +269,8 @@ Methods
         s.read(10)  # may timeout
 
         # Use:
-        poller = uselect.poll()
-        poller.register(s, uselect.POLLIN)
+        poller = select.poll()
+        poller.register(s, select.POLLIN)
         res = poller.poll(1000)  # time in milliseconds
         if not res:
             # s is still not ready for input, i.e. operation timed out
@@ -342,7 +342,7 @@ Methods
 
    Return value: number of bytes written.
 
-.. exception:: usocket.error
+.. exception:: socket.error
 
    MicroPython does NOT have this exception.
 
diff --git a/docs/library/ussl.rst b/docs/library/ssl.rst
similarity index 78%
rename from docs/library/ussl.rst
rename to docs/library/ssl.rst
index 77d278d41..4726daa59 100644
--- a/docs/library/ussl.rst
+++ b/docs/library/ssl.rst
@@ -1,7 +1,7 @@
-:mod:`ussl` -- SSL/TLS module
-=============================
+:mod:`ssl` -- SSL/TLS module
+============================
 
-.. module:: ussl
+.. module:: ssl
    :synopsis: TLS/SSL wrapper for socket objects
 
 |see_cpython_module| :mod:`python:ssl`.
@@ -13,14 +13,14 @@ facilities for network sockets, both client-side and server-side.
 Functions
 ---------
 
-.. function:: ussl.wrap_socket(sock, server_side=False, keyfile=None, certfile=None, cert_reqs=CERT_NONE, ca_certs=None, do_handshake=True)
+.. function:: ssl.wrap_socket(sock, server_side=False, keyfile=None, certfile=None, cert_reqs=CERT_NONE, ca_certs=None, do_handshake=True)
 
-   Takes a `stream` *sock* (usually usocket.socket instance of ``SOCK_STREAM`` type),
+   Takes a `stream` *sock* (usually socket.socket instance of ``SOCK_STREAM`` type),
    and returns an instance of ssl.SSLSocket, which wraps the underlying stream in
    an SSL context. Returned object has the usual `stream` interface methods like
    ``read()``, ``write()``, etc.
    A server-side SSL socket should be created from a normal socket returned from
-   :meth:`~usocket.socket.accept()` on a non-SSL listening server socket.
+   :meth:`~socket.socket.accept()` on a non-SSL listening server socket.
 
    - *do_handshake* determines whether the handshake is done as part of the ``wrap_socket``
      or whether it is deferred to be done as part of the initial reads or writes
@@ -36,7 +36,7 @@ Functions
 
 .. warning::
 
-   Some implementations of ``ussl`` module do NOT validate server certificates,
+   Some implementations of ``ssl`` module do NOT validate server certificates,
    which makes an SSL connection established prone to man-in-the-middle attacks.
 
    CPython's ``wrap_socket`` returns an ``SSLSocket`` object which has methods typical
@@ -54,8 +54,8 @@ Exceptions
 Constants
 ---------
 
-.. data:: ussl.CERT_NONE
-          ussl.CERT_OPTIONAL
-          ussl.CERT_REQUIRED
+.. data:: ssl.CERT_NONE
+          ssl.CERT_OPTIONAL
+          ssl.CERT_REQUIRED
 
     Supported values for *cert_reqs* parameter.
diff --git a/docs/library/ustruct.rst b/docs/library/struct.rst
similarity index 84%
rename from docs/library/ustruct.rst
rename to docs/library/struct.rst
index 357d622b2..92757aba8 100644
--- a/docs/library/ustruct.rst
+++ b/docs/library/struct.rst
@@ -1,7 +1,7 @@
-:mod:`ustruct` -- pack and unpack primitive data types
-======================================================
+:mod:`struct` -- pack and unpack primitive data types
+=====================================================
 
-.. module:: ustruct
+.. module:: struct
    :synopsis: pack and unpack primitive data types
 
 |see_cpython_module| :mod:`python:struct`.
@@ -12,6 +12,11 @@ Supported format codes: ``b``, ``B``, ``h``, ``H``, ``i``, ``I``, ``l``,
 ``L``, ``q``, ``Q``, ``s``, ``P``, ``f``, ``d`` (the latter 2 depending
 on the floating-point support).
 
+.. admonition:: Difference to CPython
+   :class: attention
+
+   Whitespace is not supported in format strings.
+
 Functions
 ---------
 
diff --git a/docs/library/usys.rst b/docs/library/sys.rst
similarity index 93%
rename from docs/library/usys.rst
rename to docs/library/sys.rst
index 960164385..24f9e353b 100644
--- a/docs/library/usys.rst
+++ b/docs/library/sys.rst
@@ -1,7 +1,7 @@
-:mod:`usys` -- system specific functions
-========================================
+:mod:`sys` -- system specific functions
+=======================================
 
-.. module:: usys
+.. module:: sys
    :synopsis: system specific functions
 
 |see_cpython_module| :mod:`python:sys`.
@@ -28,10 +28,10 @@ Functions
       This function is a MicroPython extension intended to provide similar
       functionality to the :mod:`atexit` module in CPython.
 
-.. function:: print_exception(exc, file=usys.stdout, /)
+.. function:: print_exception(exc, file=sys.stdout, /)
 
    Print exception with a traceback to a file-like object *file* (or
-   `usys.stdout` by default).
+   `sys.stdout` by default).
 
    .. admonition:: Difference to CPython
       :class: attention
@@ -84,7 +84,7 @@ Constants
    value directly, but instead count number of bits in it::
 
     bits = 0
-    v = usys.maxsize
+    v = sys.maxsize
     while v:
         bits += 1
         v >>= 1
@@ -113,7 +113,7 @@ Constants
    is an identifier of a board, e.g. ``"pyboard"`` for the original MicroPython
    reference board. It thus can be used to distinguish one board from another.
    If you need to check whether your program runs on MicroPython (vs other
-   Python implementation), use `usys.implementation` instead.
+   Python implementation), use `sys.implementation` instead.
 
 .. data:: stderr
 
diff --git a/docs/library/utime.rst b/docs/library/time.rst
similarity index 93%
rename from docs/library/utime.rst
rename to docs/library/time.rst
index b7c604dc7..6ca172f22 100644
--- a/docs/library/utime.rst
+++ b/docs/library/time.rst
@@ -1,12 +1,12 @@
-:mod:`utime` -- time related functions
-======================================
+:mod:`time` -- time related functions
+=====================================
 
-.. module:: utime
+.. module:: time
    :synopsis: time related functions
 
 |see_cpython_module| :mod:`python:time`.
 
-The ``utime`` module provides functions for getting the current time and date,
+The ``time`` module provides functions for getting the current time and date,
 measuring time intervals, and for delays.
 
 **Time Epoch**: Unix port uses standard for POSIX systems epoch of
@@ -74,10 +74,19 @@ Functions
 
    Delay for given number of milliseconds, should be positive or 0.
 
+   This function will delay for at least the given number of milliseconds, but
+   may take longer than that if other processing must take place, for example
+   interrupt handlers or other threads.  Passing in 0 for *ms* will still allow
+   this other processing to occur.  Use `sleep_us()` for more precise delays.
+
 .. function:: sleep_us(us)
 
    Delay for given number of microseconds, should be positive or 0.
 
+   This function attempts to provide an accurate delay of at least *us*
+   microseconds, but it may take longer if the system has other higher priority
+   processing to perform.
+
 .. function:: ticks_ms()
 
     Returns an increasing millisecond counter with an arbitrary reference point, that
@@ -110,7 +119,7 @@ Functions
    in the system. This is usually CPU clocks, and that's why the function is named that
    way. But it doesn't have to be a CPU clock, some other timing source available in a
    system (e.g. high-resolution timer) can be used instead. The exact timing unit
-   (resolution) of this function is not specified on ``utime`` module level, but
+   (resolution) of this function is not specified on ``time`` module level, but
    documentation for a specific port may provide more specific information. This
    function is intended for very fine benchmarking or very tight real-time loops.
    Avoid using it in portable code.
diff --git a/docs/library/uasyncio.rst b/docs/library/uasyncio.rst
index 0be328829..11b9c6aee 100644
--- a/docs/library/uasyncio.rst
+++ b/docs/library/uasyncio.rst
@@ -248,6 +248,14 @@ TCP stream connections
 
     This is a coroutine, and a MicroPython extension.
 
+.. method:: Stream.readexactly(n)
+
+    Read exactly *n* bytes and return them as a bytes object.
+
+    Raises an ``EOFError`` exception if the stream ends before reading *n* bytes.
+
+    This is a coroutine.
+
 .. method:: Stream.readline()
 
     Read a line and return it.
diff --git a/docs/library/uctypes.rst b/docs/library/uctypes.rst
index b3343beb7..803ddacdc 100644
--- a/docs/library/uctypes.rst
+++ b/docs/library/uctypes.rst
@@ -19,7 +19,7 @@ sub-fields.
 
 .. seealso::
 
-    Module :mod:`ustruct`
+    Module :mod:`struct`
         Standard Python way to access binary data structures (doesn't scale
         well to large and complex structures).
 
diff --git a/docs/library/zephyr.DiskAccess.rst b/docs/library/zephyr.DiskAccess.rst
new file mode 100644
index 000000000..d19d81a96
--- /dev/null
+++ b/docs/library/zephyr.DiskAccess.rst
@@ -0,0 +1,38 @@
+.. currentmodule:: zephyr
+.. _zephyr.DiskAccess:
+
+class DiskAccess -- access to disk storage
+==========================================
+
+Uses `Zephyr Disk Access API <https://docs.zephyrproject.org/latest/reference/storage/disk/access.html>`_.
+
+This class allows access to storage devices on the board, such as support for SD card controllers and
+interfacing with SD cards via SPI. Disk devices are automatically detected and initialized on boot using
+Zephyr devicetree data.
+
+The Zephyr disk access class enables the transfer of data between a disk device and an accessible memory buffer given a disk name,
+buffer, starting disk block, and number of sectors to read. MicroPython reads as many blocks as necessary to fill the buffer, so
+the number of sectors to read is found by dividing the buffer length by block size of the disk.
+
+Constructors
+------------
+
+.. class:: DiskAccess(disk_name)
+
+   Gets an object for accessing disk memory of the specific disk.
+   For accessing an SD card on the mimxrt1050_evk, ``disk_name`` would be ``SDHC``. See board documentation and
+   devicetree for usable disk names for your board (ex. RT boards use style USDHC#).
+
+Methods
+-------
+
+.. method:: DiskAccess.readblocks(block_num, buf)
+            DiskAccess.readblocks(block_num, buf, offset)
+.. method:: DiskAccess.writeblocks(block_num, buf)
+            DiskAccess.writeblocks(block_num, buf, offset)
+.. method:: DiskAccess.ioctl(cmd, arg)
+
+    These methods implement the simple and extended
+    :ref:`block protocol <block-device-interface>` defined by
+    :class:`uos.AbstractBlockDev`.
+
diff --git a/docs/library/zephyr.FlashArea.rst b/docs/library/zephyr.FlashArea.rst
new file mode 100644
index 000000000..306347d44
--- /dev/null
+++ b/docs/library/zephyr.FlashArea.rst
@@ -0,0 +1,40 @@
+.. currentmodule:: zephyr
+.. _zephyr.FlashArea:
+
+class FlashArea -- access to built-in flash storage
+===================================================
+
+Uses `Zephyr flash map API <https://docs.zephyrproject.org/latest/reference/storage/flash_map/flash_map.html#flash-map>`_.
+
+This class allows access to device flash partition data.
+Flash area structs consist of a globally unique ID number, the name of the flash device the partition is in,
+the start offset (expressed in relation to the flash memory beginning address per partition),
+and the size of the partition that the device represents. For fixed flash partitions, data from the device
+tree is used; however, fixed flash partitioning is not enforced in MicroPython because MCUBoot is not enabled.
+
+Constructors
+------------
+
+.. class:: FlashArea(id, block_size)
+
+   Gets an object for accessing flash memory at partition specified by ``id`` and with block size of ``block_size``.
+
+   ``id`` values are integers correlating to fixed flash partitions defined in the devicetree.
+   A commonly used partition is the designated flash storage area defined as ``FlashArea.STORAGE`` if
+   ``FLASH_AREA_LABEL_EXISTS(storage)`` returns true at boot.
+   Zephyr devicetree fixed flash partitions are ``boot_partition``, ``slot0_partition``, ``slot1_partition``, and
+   ``scratch_partition``. Because MCUBoot is not enabled by default for MicroPython, these fixed partitions can be accessed by
+   ID integer values 1, 2, 3, and 4, respectively.
+
+Methods
+-------
+
+.. method:: FlashArea.readblocks(block_num, buf)
+            FlashArea.readblocks(block_num, buf, offset)
+.. method:: FlashArea.writeblocks(block_num, buf)
+            FlashArea.writeblocks(block_num, buf, offset)
+.. method:: FlashArea.ioctl(cmd, arg)
+
+    These methods implement the simple and extended
+    :ref:`block protocol <block-device-interface>` defined by
+    :class:`uos.AbstractBlockDev`.
diff --git a/docs/library/zephyr.rst b/docs/library/zephyr.rst
new file mode 100644
index 000000000..da3d14a09
--- /dev/null
+++ b/docs/library/zephyr.rst
@@ -0,0 +1,60 @@
+.. currentmodule:: zephyr
+
+:mod:`zephyr` --- functionality specific to the Zephyr port
+===========================================================
+
+.. module:: zephyr
+    :synopsis: functionality specific to Zephyr
+
+The ``zephyr`` module contains functions and classes specific to the Zephyr port.
+
+Functions
+---------
+
+.. function:: is_preempt_thread()
+
+   Returns true if the current thread is a preemptible thread.
+
+   Zephyr preemptible threads are those with non-negative priority values (low priority levels), which therefore,
+   can be supplanted as soon as a higher or equal priority thread becomes ready.
+
+.. function:: current_tid()
+
+   Returns the thread id of the current thread, which is used to reference the thread.
+
+.. function:: thread_analyze()
+
+   Runs the Zephyr debug thread analyzer on the current thread and prints stack size statistics in the format:
+
+    "``thread_name``-20s: STACK: unused ``available_stack_space`` usage ``stack_space_used``
+    / ``stack_size`` (``percent_stack_space_used`` %); CPU: ``cpu_utilization`` %"
+
+    * *CPU utilization is only printed if runtime statistics are configured via the ``CONFIG_THREAD_RUNTIME_STATS`` kconfig*
+
+   This function can only be accessed if ``CONFIG_THREAD_ANALYZER`` is configured for the port in ``zephyr/prj.conf``.
+   For more infomation, see documentation for Zephyr `thread analyzer
+   <https://docs.zephyrproject.org/latest/guides/debug_tools/thread-analyzer.html#thread-analyzer>`_.
+
+.. function:: shell_exec(cmd_in)
+
+   Executes the given command on an UART backend. This function can only be accessed if ``CONFIG_SHELL_BACKEND_SERIAL``
+   is configured for the port in ``zephyr/prj.conf``.
+
+   A list of possible commands can be found in the documentation for Zephyr `shell commands <https://docs.zephyrproject.org/latest/reference/shell/index.html?highlight=shell_execute_cmd#commands>`_.
+
+Classes
+-------
+
+.. toctree::
+    :maxdepth: 1
+
+    zephyr.DiskAccess.rst
+    zephyr.FlashArea.rst
+
+Additional Modules
+------------------
+
+.. toctree::
+    :maxdepth: 1
+
+    zephyr.zsensor.rst
diff --git a/docs/library/zephyr.zsensor.rst b/docs/library/zephyr.zsensor.rst
new file mode 100644
index 000000000..4eadc926d
--- /dev/null
+++ b/docs/library/zephyr.zsensor.rst
@@ -0,0 +1,123 @@
+.. currentmodule:: zsensor
+
+:mod:`zsensor` --- Zephyr sensor bindings
+=========================================
+
+.. module:: zsensor
+    :synopsis: zephyr sensor bindings
+
+The ``zsensor`` module contains a class for using sensors with Zephyr.
+
+.. _zsensor.Sensor:
+
+class Sensor --- sensor control for the Zephyr port
+---------------------------------------------------
+
+Use this class to access data from sensors on your board.
+See Zephyr documentation for sensor usage here: `Sensors
+<https://docs.zephyrproject.org/latest/reference/peripherals/sensor.html?highlight=sensor#sensors>`_.
+
+Sensors are defined in the Zephyr devicetree for each board. The quantities that a given sensor can
+measure are called a sensor channels. Sensors can have multiple channels to represent different axes
+of one property or different properties a sensor can measure. See `Channels`_ below for defined sensor
+channels.
+
+Constructor
+~~~~~~~~~~~
+
+.. class:: Sensor(device_name)
+
+    Device names are defined in the devicetree for your board.
+    For example, the device name for the accelerometer in the FRDM-k64f board is "FXOS8700".
+
+Methods
+~~~~~~~
+
+.. method:: Sensor.measure()
+
+    Obtains a measurement sample from the sensor device using Zephyr sensor_sample_fetch and
+    stores it in an internal driver buffer as a useful value, a pair of (integer part of value,
+    fractional part of value in 1-millionths).
+    Returns none if successful or OSError value if failure.
+
+.. method:: Sensor.get_float(sensor_channel)
+
+    Returns the value of the sensor measurement sample as a float.
+
+.. method:: Sensor.get_micros(sensor_channel)
+
+    Returns the value of the sensor measurement sample in millionths.
+    (Ex. value of ``(1, 500000)`` returns as ``1500000``)
+
+.. method:: Sensor.get_millis(sensor_channel)
+
+    Returns the value of sensor measurement sample in thousandths.
+    (Ex. value of ``(1, 500000)`` returns as ``1500``)
+
+.. method:: Sensor.get_int(sensor_channel)
+
+    Returns only the integer value of the measurement sample.
+    (Ex. value of ``(1, 500000)`` returns as ``1``)
+
+Channels
+~~~~~~~~
+
+.. data:: ACCEL_X
+
+    Acceleration on the X axis, in m/s^2.
+
+.. data:: ACCEL_Y
+
+    Acceleration on the Y axis, in m/s^2.
+
+.. data:: ACCEL_Z
+
+    Acceleration on the Z axis, in m/s^2.
+
+.. data:: GYRO_X
+
+    Angular velocity around the X axis, in radians/s.
+
+.. data:: GYRO_Y
+
+    Angular velocity around the Y axis, in radians/s.
+
+.. data:: GYRO_Z
+
+    Angular velocity around the Z axis, in radians/s.
+
+.. data:: MAGN_X
+
+    Magnetic field on the X axis, in Gauss.
+
+.. data:: MAGN_Y
+
+    Magnetic field on the Y axis, in Gauss.
+
+.. data:: MAGN_Z
+
+    Magnetic field on the Z axis, in Gauss.
+
+.. data:: DIE_TEMP
+
+    Device die temperature in degrees Celsius.
+
+.. data:: PRESS
+
+    Pressure in kilopascal.
+
+.. data:: PROX
+
+    Proximity. Dimensionless. A value of 1 indicates that an object is close.
+
+.. data:: HUMIDITY
+
+    Humidity, in percent.
+
+.. data:: LIGHT
+
+    Illuminance in visible spectrum, in lux.
+
+.. data:: ALTITUDE
+
+    Altitude, in meters.
diff --git a/docs/library/uzlib.rst b/docs/library/zlib.rst
similarity index 93%
rename from docs/library/uzlib.rst
rename to docs/library/zlib.rst
index d40c46145..96d6c2452 100644
--- a/docs/library/uzlib.rst
+++ b/docs/library/zlib.rst
@@ -1,7 +1,7 @@
-:mod:`uzlib` -- zlib decompression
-==================================
+:mod:`zlib` -- zlib decompression
+=================================
 
-.. module:: uzlib
+.. module:: zlib
    :synopsis: zlib decompression
 
 |see_cpython_module| :mod:`python:zlib`.
diff --git a/docs/pyboard/quickref.rst b/docs/pyboard/quickref.rst
index 3dbd09304..ed56811dd 100644
--- a/docs/pyboard/quickref.rst
+++ b/docs/pyboard/quickref.rst
@@ -45,7 +45,7 @@ See :mod:`pyb`. ::
 Delay and timing
 ----------------
 
-Use the :mod:`time <utime>` module::
+Use the :mod:`time <time>` module::
 
     import time
 
@@ -191,7 +191,7 @@ See :ref:`pyb.SPI <pyb.SPI>`. ::
 
     from pyb import SPI
 
-    spi = SPI(1, SPI.MASTER, baudrate=200000, polarity=1, phase=0)
+    spi = SPI(1, SPI.CONTROLLER, baudrate=200000, polarity=1, phase=0)
     spi.send('hello')
     spi.recv(5) # receive 5 bytes on the bus
     spi.send_recv('hello') # send and receive 5 bytes
@@ -210,15 +210,35 @@ eg ``I2C(1)``.  Software I2C is also available by explicitly specifying the
     i2c = I2C('X', freq=400000)                 # create hardware I2c object
     i2c = I2C(scl='X1', sda='X2', freq=100000)  # create software I2C object
 
-    i2c.scan()                          # returns list of slave addresses
-    i2c.writeto(0x42, 'hello')          # write 5 bytes to slave with address 0x42
-    i2c.readfrom(0x42, 5)               # read 5 bytes from slave
+    i2c.scan()                          # returns list of peripheral addresses
+    i2c.writeto(0x42, 'hello')          # write 5 bytes to peripheral with address 0x42
+    i2c.readfrom(0x42, 5)               # read 5 bytes from peripheral
 
-    i2c.readfrom_mem(0x42, 0x10, 2)     # read 2 bytes from slave 0x42, slave memory 0x10
-    i2c.writeto_mem(0x42, 0x10, 'xy')   # write 2 bytes to slave 0x42, slave memory 0x10
+    i2c.readfrom_mem(0x42, 0x10, 2)     # read 2 bytes from peripheral 0x42, peripheral memory 0x10
+    i2c.writeto_mem(0x42, 0x10, 'xy')   # write 2 bytes to peripheral 0x42, peripheral memory 0x10
 
 Note: for legacy I2C support see :ref:`pyb.I2C <pyb.I2C>`.
 
+I2S bus
+-------
+
+See :ref:`machine.I2S <machine.I2S>`. ::
+
+    from machine import I2S, Pin
+    
+    i2s = I2S(2, sck=Pin('Y6'), ws=Pin('Y5'), sd=Pin('Y8'), mode=I2S.TX, bits=16, format=I2S.STEREO, rate=44100, ibuf=40000) # create I2S object
+    i2s.write(buf)             # write buffer of audio samples to I2S device
+    
+    i2s = I2S(1, sck=Pin('X5'), ws=Pin('X6'), sd=Pin('Y4'), mode=I2S.RX, bits=16, format=I2S.MONO, rate=22050, ibuf=40000) # create I2S object
+    i2s.readinto(buf)          # fill buffer with audio samples from I2S device
+    
+The I2S class is currently available as a Technical Preview.  During the preview period, feedback from 
+users is encouraged.  Based on this feedback, the I2S class API and implementation may be changed.
+
+PYBv1.0/v1.1 has one I2S bus with id=2.  
+PYBD-SFxW has two I2S buses with id=1 and id=2.  
+I2S is shared with SPI.  
+    
 CAN bus (controller area network)
 ---------------------------------
 
diff --git a/docs/pyboard/tutorial/amp_skin.rst b/docs/pyboard/tutorial/amp_skin.rst
index bcb583261..b6558959e 100644
--- a/docs/pyboard/tutorial/amp_skin.rst
+++ b/docs/pyboard/tutorial/amp_skin.rst
@@ -30,7 +30,7 @@ To set the volume, define the following function::
 
     import pyb
     def volume(val):
-        pyb.I2C(1, pyb.I2C.MASTER).mem_write(val, 46, 0)
+        pyb.I2C(1, pyb.I2C.CONTROLLER).mem_write(val, 46, 0)
 
 Then you can do::
 
diff --git a/docs/pyboard/tutorial/lcd_skin.rst b/docs/pyboard/tutorial/lcd_skin.rst
index 288ac1bf0..4df004160 100644
--- a/docs/pyboard/tutorial/lcd_skin.rst
+++ b/docs/pyboard/tutorial/lcd_skin.rst
@@ -51,7 +51,7 @@ MPR121 capacitive touch sensor has address 90.
 To get started, try::
 
     >>> import pyb
-    >>> i2c = pyb.I2C(1, pyb.I2C.MASTER)
+    >>> i2c = pyb.I2C(1, pyb.I2C.CONTROLLER)
     >>> i2c.mem_write(4, 90, 0x5e)
     >>> touch = i2c.mem_read(1, 90, 0)[0]
 
@@ -68,7 +68,7 @@ directory or ``lib/`` directory) and then try::
 
     >>> import pyb
     >>> import mpr121
-    >>> m = mpr121.MPR121(pyb.I2C(1, pyb.I2C.MASTER))
+    >>> m = mpr121.MPR121(pyb.I2C(1, pyb.I2C.CONTROLLER))
     >>> for i in range(100):
     ...   print(m.touch_status())
     ...   pyb.delay(100)
@@ -80,7 +80,7 @@ Try touching each one in turn.
 Note that if you put the LCD skin in the Y-position, then you need to
 initialise the I2C bus using::
 
-    >>> m = mpr121.MPR121(pyb.I2C(2, pyb.I2C.MASTER))
+    >>> m = mpr121.MPR121(pyb.I2C(2, pyb.I2C.CONTROLLER))
 
 There is also a demo which uses the LCD and the touch sensors together,
 and can be found `here <http://micropython.org/resources/examples/lcddemo.py>`__.
diff --git a/docs/reference/constrained.rst b/docs/reference/constrained.rst
index 9c68bab9a..2a5f9d7fd 100644
--- a/docs/reference/constrained.rst
+++ b/docs/reference/constrained.rst
@@ -122,7 +122,7 @@ execution from Flash, RAM may be saved as follows. The data should be located in
 Python modules and frozen as bytecode. The data must be defined as `bytes`
 objects. The compiler 'knows' that `bytes` objects are immutable and ensures
 that the objects remain in flash memory rather than being copied to RAM. The
-`ustruct` module can assist in converting between `bytes` types and other
+`struct` module can assist in converting between `bytes` types and other
 Python built-in types.
 
 When considering the implications of frozen bytecode, note that in Python
@@ -261,7 +261,7 @@ were a string.
 The Python funcitons `eval` and `exec` invoke the compiler at runtime, which
 requires significant amounts of RAM. Note that the ``pickle`` library from
 `micropython-lib` employs `exec`. It may be more RAM efficient to use the
-`ujson` library for object serialisation.
+`json` library for object serialisation.
 
 **Storing strings in flash**
 
@@ -444,7 +444,7 @@ RAM usage and speed.
 
 Where variables are required whose size is neither a byte nor a machine word
 there are standard libraries which can assist in storing these efficiently and
-in performing conversions. See the `array`, `ustruct` and `uctypes`
+in performing conversions. See the `array`, `struct` and `uctypes`
 modules.
 
 Footnote: gc.collect() return value
diff --git a/docs/reference/filesystem.rst b/docs/reference/filesystem.rst
index 9e7e6212d..114e59735 100644
--- a/docs/reference/filesystem.rst
+++ b/docs/reference/filesystem.rst
@@ -40,7 +40,7 @@ Block devices
 -------------
 
 A block device is an instance of a class that implements the
-:class:`uos.AbstractBlockDev` protocol.
+:class:`os.AbstractBlockDev` protocol.
 
 Built-in block devices
 ~~~~~~~~~~~~~~~~~~~~~~
@@ -116,8 +116,8 @@ It can be used as follows::
 
 An example of a block device that supports both the simple and extended
 interface (i.e. both signatures and behaviours of the
-:meth:`uos.AbstractBlockDev.readblocks` and
-:meth:`uos.AbstractBlockDev.writeblocks` methods) is::
+:meth:`os.AbstractBlockDev.readblocks` and
+:meth:`os.AbstractBlockDev.writeblocks` methods) is::
 
     class RAMBlockDev:
         def __init__(self, block_size, num_blocks):
@@ -148,7 +148,7 @@ interface (i.e. both signatures and behaviours of the
                 return 0
 
 As it supports the extended interface, it can be used with :class:`littlefs
-<uos.VfsLfs2>`::
+<os.VfsLfs2>`::
 
     import os
 
@@ -166,8 +166,8 @@ normally would be used from Python code, for example::
 Filesystems
 -----------
 
-MicroPython ports can provide implementations of :class:`FAT <uos.VfsFat>`,
-:class:`littlefs v1 <uos.VfsLfs1>` and :class:`littlefs v2 <uos.VfsLfs2>`.
+MicroPython ports can provide implementations of :class:`FAT <os.VfsFat>`,
+:class:`littlefs v1 <os.VfsLfs1>` and :class:`littlefs v2 <os.VfsLfs2>`.
 
 The following table shows which filesystems are included in the firmware by
 default for given port/board combinations, however they can be optionally
diff --git a/docs/reference/glossary.rst b/docs/reference/glossary.rst
index 27a66aa76..da951189e 100644
--- a/docs/reference/glossary.rst
+++ b/docs/reference/glossary.rst
@@ -184,7 +184,7 @@ Glossary
         ``close()``, etc. A stream is an important concept in MicroPython;
         many I/O objects implement the stream interface, and thus can be used
         consistently and interchangeably in different contexts. For more
-        information on streams in MicroPython, see the `uio` module.
+        information on streams in MicroPython, see the `io` module.
 
     UART
         Acronym for "Universal Asynchronous Receiver/Transmitter". This is a
diff --git a/docs/reference/packages.rst b/docs/reference/packages.rst
index e9adfc176..eb44992ed 100644
--- a/docs/reference/packages.rst
+++ b/docs/reference/packages.rst
@@ -1,3 +1,5 @@
+.. _packages:
+
 Distribution packages, package management, and deploying applications
 =====================================================================
 
diff --git a/docs/reference/speed_python.rst b/docs/reference/speed_python.rst
index aa9777859..85e956e8e 100644
--- a/docs/reference/speed_python.rst
+++ b/docs/reference/speed_python.rst
@@ -91,9 +91,11 @@ code these should be pre-allocated and passed as arguments or as bound objects.
 
 When passing slices of objects such as `bytearray` instances, Python creates
 a copy which involves allocation of the size proportional to the size of slice.
-This can be alleviated using a `memoryview` object. `memoryview` itself
-is allocated on heap, but is a small, fixed-size object, regardless of the size
-of slice it points too.
+This can be alleviated using a `memoryview` object. The `memoryview` itself
+is allocated on the heap, but is a small, fixed-size object, regardless of the size
+of slice it points too. Slicing a `memoryview` creates a new `memoryview`, so this
+cannot be done in an interrupt service routine. Further, the slice syntax ``a:b``
+causes further allocation by instantiating a ``slice(a, b)`` object.
 
 .. code:: python
 
@@ -123,7 +125,7 @@ This is a process known as profiling and is covered in textbooks and
 (for standard Python) supported by various software tools. For the type of
 smaller embedded application likely to be running on MicroPython platforms
 the slowest function or method can usually be established by judicious use
-of the timing ``ticks`` group of functions documented in `utime`.
+of the timing ``ticks`` group of functions documented in `time`.
 Code execution time can be measured in ms, us, or CPU cycles.
 
 The following enables any function or method to be timed by adding an
@@ -134,9 +136,9 @@ The following enables any function or method to be timed by adding an
     def timed_function(f, *args, **kwargs):
         myname = str(f).split(' ')[1]
         def new_func(*args, **kwargs):
-            t = utime.ticks_us()
+            t = time.ticks_us()
             result = f(*args, **kwargs)
-            delta = utime.ticks_diff(utime.ticks_us(), t)
+            delta = time.ticks_diff(time.ticks_us(), t)
             print('Function {} Time = {:6.3f}ms'.format(myname, delta/1000))
             return result
         return new_func
diff --git a/docs/rp2/general.rst b/docs/rp2/general.rst
index 9ff83a965..7042d0d25 100644
--- a/docs/rp2/general.rst
+++ b/docs/rp2/general.rst
@@ -10,9 +10,27 @@ the RP2040.
 Technical specifications and SoC datasheets
 -------------------------------------------
 
-Datasheets!
+For detailed technical specifications, please refer to the `datasheets
+<https://datasheets.raspberrypi.org/rp2040/rp2040-datasheet.pdf>`_
 
-Short summary of tech specs!
+The RP2040 microcontroller is manufactured on a 40 nm silicon process in a 7x7mm
+QFN-56 SMD package. The key features include:
 
-Description of general structure of the port (it's built on top of the APIs
-provided by the Raspberry Pi SDK).
+* 133 MHz dual ARM Cortex-M0+ cores (overclockable to over 400 MHz)
+* 264KB SRAM in six independent banks
+* No internal Flash or EEPROM memory (after reset, the bootloader loads
+  firmware from either the external flash memory or USB bus into internal SRAM)
+* QSPI bus controller, which
+  supports up to 16 MB of external Flash memory
+* On-chip programmable LDO togenerate core voltage
+* 2 on-chip PLLs to generate USB and core clocks
+* 30 GPIOpins, of which 4 can optionally be used as analog inputs
+
+The peripherals include:
+
+* 2 UARTs
+* 2 SPI controllers
+* 2 I2C contollers
+* 16 PWM channels
+* USB 1.1 controller
+* 8 PIO state machines
diff --git a/docs/rp2/img/pico_pinout.png b/docs/rp2/img/pico_pinout.png
new file mode 100644
index 000000000..7bee29274
Binary files /dev/null and b/docs/rp2/img/pico_pinout.png differ
diff --git a/docs/rp2/img/rpipico.jpg b/docs/rp2/img/rpipico.jpg
deleted file mode 100644
index 336d35827..000000000
Binary files a/docs/rp2/img/rpipico.jpg and /dev/null differ
diff --git a/docs/rp2/quickref.rst b/docs/rp2/quickref.rst
index 4c8c02dc0..ac9cdb86c 100644
--- a/docs/rp2/quickref.rst
+++ b/docs/rp2/quickref.rst
@@ -3,7 +3,7 @@
 Quick reference for the RP2
 ===========================
 
-.. image:: img/rpipico.jpg
+.. image:: img/pico_pinout.png
     :alt: Raspberry Pi Pico
     :width: 640px
 
@@ -27,10 +27,9 @@ a troubleshooting subsection.
 General board control
 ---------------------
 
-The MicroPython REPL is on the USB serial port.
-Tab-completion is useful to find out what methods an object has.
-Paste mode (ctrl-E) is useful to paste a large slab of Python code into
-the REPL.
+The MicroPython REPL is accessed via the USB serial port. Tab-completion is useful to
+find out what methods an object has. Paste mode (ctrl-E) is useful to paste a
+large slab of Python code into the REPL.
 
 The :mod:`machine` module::
 
@@ -46,7 +45,7 @@ The :mod:`rp2` module::
 Delay and timing
 ----------------
 
-Use the :mod:`time <utime>` module::
+Use the :mod:`time <time>` module::
 
     import time
 
@@ -59,7 +58,19 @@ Use the :mod:`time <utime>` module::
 Timers
 ------
 
-How do they work?
+RP2040's system timer peripheral provides a global microsecond timebase and
+generates interrupts for it.  The software timer is available currently,
+and there are unlimited number of them (memory permitting). There is no need
+to specify the timer id (id=-1 is supported at the moment) as it will default
+to this.
+
+Use the :mod:`machine.Timer` class::
+
+    from machine import Timer
+
+    tim = Timer(period=5000, mode=Timer.ONE_SHOT, callback=lambda t:print(1))
+    tim.init(period=2000, mode=Timer.PERIODIC, callback=lambda t:print(2))
+
 
 .. _rp2_Pins_and_GPIO:
 
@@ -84,19 +95,28 @@ Use the :ref:`machine.Pin <machine.Pin>` class::
 UART (serial bus)
 -----------------
 
+There are two UARTs, UART0 and UART1. UART0 can be mapped to GPIO 0/1, 12/13
+and 16/17, and UART1 to GPIO 4/5 and 8/9.
+
+
 See :ref:`machine.UART <machine.UART>`. ::
 
-    from machine import UART
-
-    uart1 = UART(1, baudrate=9600, tx=33, rx=32)
+    from machine import UART, Pin
+    uart1 = UART(1, baudrate=9600, tx=Pin(4), rx=Pin(5))
     uart1.write('hello')  # write 5 bytes
     uart1.read(5)         # read up to 5 bytes
 
+.. note::
+
+    REPL over UART is disabled by default. You can see the :ref:`rp2_intro` for
+    details on how to enable REPL over UART.
+
 
 PWM (pulse width modulation)
 ----------------------------
 
-How does PWM work on the RPi RP2xxx?
+There are 8 independent channels each of which have 2 outputs making it 16
+PWM channels in total which can be clocked from 7Hz to 125Mhz.
 
 Use the ``machine.PWM`` class::
 
@@ -112,14 +132,18 @@ Use the ``machine.PWM`` class::
 ADC (analog to digital conversion)
 ----------------------------------
 
-How does the ADC module work?
+RP2040 has five ADC channels in total, four of which are 12-bit SAR based
+ADCs: GP26, GP27, GP28 and GP29. The input signal for ADC0, ADC1, ADC2 and
+ADC3 can be connected with GP26, GP27, GP28, GP29 respectively (On Pico board,
+GP29 is connected to VSYS). The standard ADC range is 0-3.3V. The fifth
+channel is connected to the in-built temperature sensor and can be used for
+measuring the temperature.
 
 Use the :ref:`machine.ADC <machine.ADC>` class::
 
-    from machine import ADC
-
-    adc = ADC(Pin(32))          # create ADC object on ADC pin
-    adc.read_u16()              # read value, 0-65535 across voltage range 0.0v - 3.3v
+    from machine import ADC, Pin
+    adc = ADC(Pin(26))     # create ADC object on ADC pin
+    adc.read_u16()         # read value, 0-65535 across voltage range 0.0v - 3.3v
 
 Software SPI bus
 ----------------
@@ -132,7 +156,7 @@ Software SPI (using bit-banging) works on all pins, and is accessed via the
     # construct a SoftSPI bus on the given pins
     # polarity is the idle state of SCK
     # phase=0 means sample on the first edge of SCK, phase=1 means the second
-    spi = SoftSPI(baudrate=100000, polarity=1, phase=0, sck=Pin(0), mosi=Pin(2), miso=Pin(4))
+    spi = SoftSPI(baudrate=100_000, polarity=1, phase=0, sck=Pin(0), mosi=Pin(2), miso=Pin(4))
 
     spi.init(baudrate=200000) # set the baudrate
 
@@ -156,14 +180,15 @@ Software SPI (using bit-banging) works on all pins, and is accessed via the
 Hardware SPI bus
 ----------------
 
-Hardware SPI is accessed via the :ref:`machine.SPI <machine.SPI>` class and
-has the same methods as software SPI above::
+The RP2040 has 2 hardware SPI buses which is accessed via the
+:ref:`machine.SPI <machine.SPI>` class and has the same methods as software
+SPI above::
 
     from machine import Pin, SPI
 
-    spi = SPI(1, 10000000)
-    spi = SPI(1, 10000000, sck=Pin(14), mosi=Pin(13), miso=Pin(12))
-    spi = SPI(2, baudrate=80000000, polarity=0, phase=0, bits=8, firstbit=0, sck=Pin(18), mosi=Pin(23), miso=Pin(19))
+    spi = SPI(1, 10_000_000)  # Default assignment: sck=Pin(10), mosi=Pin(11), miso=Pin(8)
+    spi = SPI(1, 10_000_000, sck=Pin(14), mosi=Pin(15), miso=Pin(12))
+    spi = SPI(0, baudrate=80_000_000, polarity=0, phase=0, bits=8, sck=Pin(6), mosi=Pin(7), miso=Pin(4))
 
 Software I2C bus
 ----------------
@@ -173,7 +198,7 @@ accessed via the :ref:`machine.SoftI2C <machine.SoftI2C>` class::
 
     from machine import Pin, SoftI2C
 
-    i2c = SoftI2C(scl=Pin(5), sda=Pin(4), freq=100000)
+    i2c = SoftI2C(scl=Pin(5), sda=Pin(4), freq=100_000)
 
     i2c.scan()              # scan for devices
 
@@ -181,7 +206,7 @@ accessed via the :ref:`machine.SoftI2C <machine.SoftI2C>` class::
     i2c.writeto(0x3a, '12') # write '12' to device with address 0x3a
 
     buf = bytearray(10)     # create a buffer with 10 bytes
-    i2c.writeto(0x3a, buf)  # write the given buffer to the slave
+    i2c.writeto(0x3a, buf)  # write the given buffer to the peripheral
 
 Hardware I2C bus
 ----------------
@@ -191,8 +216,8 @@ has the same methods as software I2C above::
 
     from machine import Pin, I2C
 
-    i2c = I2C(0)
-    i2c = I2C(1, scl=Pin(5), sda=Pin(4), freq=400000)
+    i2c = I2C(0)   # default assignment: scl=Pin(9), sda=Pin(8)
+    i2c = I2C(1, scl=Pin(3), sda=Pin(2), freq=400_000)
 
 Real time clock (RTC)
 ---------------------
@@ -202,13 +227,15 @@ See :ref:`machine.RTC <machine.RTC>` ::
     from machine import RTC
 
     rtc = RTC()
-    rtc.datetime((2017, 8, 23, 2, 12, 48, 0, 0)) # set a specific date and time
+    rtc.datetime((2017, 8, 23, 2, 12, 48, 0, 0)) # set a specific date and
+                                                 # time, eg. 2017/8/23 1:12:48
     rtc.datetime() # get date and time
 
 WDT (Watchdog timer)
 --------------------
 
-Is there a watchdog timer?
+The RP2040 has a watchdog which is a countdown timer that can restart
+parts of the chip if it reaches zero.
 
 See :ref:`machine.WDT <machine.WDT>`. ::
 
@@ -218,21 +245,6 @@ See :ref:`machine.WDT <machine.WDT>`. ::
     wdt = WDT(timeout=5000)
     wdt.feed()
 
-Deep-sleep mode
----------------
-
-Is there deep-sleep support for the rp2?
-
-The following code can be used to sleep, wake and check the reset cause::
-
-    import machine
-
-    # check if the device woke from a deep sleep
-    if machine.reset_cause() == machine.DEEPSLEEP_RESET:
-        print('woke from a deep sleep')
-
-    # put the device to sleep for 10 seconds
-    machine.deepsleep(10000)
 
 OneWire driver
 --------------
diff --git a/docs/templates/topindex.html b/docs/templates/topindex.html
index 42233942b..c14f840ce 100644
--- a/docs/templates/topindex.html
+++ b/docs/templates/topindex.html
@@ -66,6 +66,14 @@
         <a class="biglink" href="{{ pathto("wipy/quickref") }}">Quick reference for the WiPy/CC3200</a><br/>
         <span class="linkdescr">pinout for the WiPy/CC3200, snippets of useful code, and a tutorial</span>
       </p>
+      <p class="biglink">
+        <a class="biglink" href="{{ pathto("unix/quickref") }}">Quick reference for UNIX and Windows</a><br/>
+        <span class="linkdescr">command-line reference</span>
+      </p>
+      <p class="biglink">
+        <a class="biglink" href="{{ pathto("zephyr/quickref") }}">Quick reference for the Zephyr port</a><br/>
+        <span class="linkdescr">snippets of useful code and a tutorial</span>
+      </p>
     </td>
   </tr></table>
 
diff --git a/docs/wipy/general.rst b/docs/wipy/general.rst
index b1109c495..7f24435db 100644
--- a/docs/wipy/general.rst
+++ b/docs/wipy/general.rst
@@ -296,8 +296,8 @@ and put it in '/flash/cert/'. Then do::
   ss = ssl.wrap_socket(s, cert_reqs=ssl.CERT_REQUIRED, ca_certs='/flash/cert/ca.pem')
   ss.connect(socket.getaddrinfo('cloud.blynk.cc', 8441)[0][-1])
 
-Incompatibilities in uhashlib module
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Incompatibilities in hashlib module
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Due to hardware implementation details of the WiPy, data must be buffered before being
 digested, which would make it impossible to calculate the hash of big blocks of data that
@@ -310,7 +310,7 @@ initial one) is a multiple of 4 bytes.** The last chunk may be of any length.
 
 Example::
 
-   hash = uhashlib.sha1('abcd1234', 1001)    # length of the initial piece is multiple of 4 bytes
+   hash = hashlib.sha1('abcd1234', 1001)    # length of the initial piece is multiple of 4 bytes
    hash.update('1234')                       # also multiple of 4 bytes
    ...
    hash.update('12345')                      # last chunk may be of any length
@@ -366,7 +366,7 @@ Adhoc VFS-like support
 ~~~~~~~~~~~~~~~~~~~~~~
 
 WiPy doesn't implement full MicroPython VFS support, instead following
-functions are defined in ``uos`` module:
+functions are defined in ``os`` module:
 
 .. function:: mount(block_device, mount_point, \*, readonly=False)
 
diff --git a/docs/wipy/quickref.rst b/docs/wipy/quickref.rst
index a22ea45b5..f9ea3d501 100644
--- a/docs/wipy/quickref.rst
+++ b/docs/wipy/quickref.rst
@@ -107,8 +107,8 @@ See :ref:`machine.SPI <machine.SPI>`. ::
 
     from machine import SPI
 
-    # configure the SPI master @ 2MHz
-    spi = SPI(0, SPI.MASTER, baudrate=200000, polarity=0, phase=0)
+    # configure the SPI controller @ 2MHz
+    spi = SPI(0, SPI.CONTROLLER, baudrate=2_000_000, polarity=0, phase=0)
     spi.write('hello')
     spi.read(5) # receive 5 bytes on the bus
     rbuf = bytearray(5)
@@ -122,11 +122,11 @@ See :ref:`machine.I2C <machine.I2C>`. ::
     from machine import I2C
     # configure the I2C bus
     i2c = I2C(baudrate=100000)
-    i2c.scan() # returns list of slave addresses
-    i2c.writeto(0x42, 'hello') # send 5 bytes to slave with address 0x42
-    i2c.readfrom(0x42, 5) # receive 5 bytes from slave
-    i2c.readfrom_mem(0x42, 0x10, 2) # read 2 bytes from slave 0x42, slave memory 0x10
-    i2c.writeto_mem(0x42, 0x10, 'xy') # write 2 bytes to slave 0x42, slave memory 0x10
+    i2c.scan() # returns list of peripheral addresses
+    i2c.writeto(0x42, 'hello') # send 5 bytes to peripheral with address 0x42
+    i2c.readfrom(0x42, 5) # receive 5 bytes from peripheral
+    i2c.readfrom_mem(0x42, 0x10, 2) # read 2 bytes from peripheral 0x42, peripheral memory 0x10
+    i2c.writeto_mem(0x42, 0x10, 'xy') # write 2 bytes to peripheral 0x42, peripheral memory 0x10
 
 Watchdog timer (WDT)
 --------------------
diff --git a/docs/zephyr/general.rst b/docs/zephyr/general.rst
new file mode 100644
index 000000000..362f03ada
--- /dev/null
+++ b/docs/zephyr/general.rst
@@ -0,0 +1,22 @@
+.. _zephyr_general:
+
+General information about the Zephyr port
+=========================================
+
+The Zephyr Project is a Linux Foundation hosted Collaboration Project. It’s an open
+source collaborative effort uniting developers and users in building a
+small, scalable, real-time operating system (RTOS) optimized for resource-constrained
+devices, across multiple architectures.
+
+Multitude of boards
+-------------------
+
+There is a multitude of modules and boards from different sources that are supported
+by the Zephyr OS. All boards supported by Zephyr (with standard level of features
+support, like UART console) should work with MicroPython (but not all were tested).
+The FRDM-K64f board is taken as a reference board for the port for this documentation.
+If you have another board, please make sure you have a datasheet, schematics and other
+reference materials for your board handy to look up various aspects of your board
+functioning.
+
+For a full list of Zephyr supported boards click `here (external link) <https://docs.zephyrproject.org/latest/boards/index.html#boards>`_
diff --git a/docs/zephyr/quickref.rst b/docs/zephyr/quickref.rst
new file mode 100644
index 000000000..783621316
--- /dev/null
+++ b/docs/zephyr/quickref.rst
@@ -0,0 +1,157 @@
+.. _zephyr_quickref:
+
+Quick reference for the Zephyr port
+===================================
+
+Below is a quick reference for the Zephyr port. If it is your first time working with this port please consider reading the following sections first:
+
+.. toctree::
+   :maxdepth: 1
+
+   general.rst
+   tutorial/index.rst
+
+Running MicroPython
+-------------------
+
+See the corresponding section of the tutorial: :ref:`intro`.
+
+Delay and timing
+----------------
+
+Use the :mod:`time <utime>` module::
+
+    import time
+
+    time.sleep(1)               # sleep for 1 second
+    time.sleep_ms(500)          # sleep for 500 milliseconds
+    time.sleep_us(10)           # sleep for 10 microseconds
+    start = time.ticks_ms()     # get millisecond counter
+    delta = time.ticks_diff(time.ticks_ms(), start) # compute time difference
+
+Pins and GPIO
+-------------
+
+Use the :ref:`machine.Pin <machine.Pin>` class::
+
+    from machine import Pin
+
+    pin = Pin(("GPIO_1", 21), Pin.IN)   # create input pin on GPIO1
+    print(pin)                          # print pin port and number
+
+    pin.init(Pin.OUT, Pin.PULL_UP, value=1)     # reinitialize pin
+
+    pin.value(1)                        # set pin to high
+    pin.value(0)                        # set pin to low
+
+    pin.on()                            # set pin to high
+    pin.off()                           # set pin to low
+
+    pin = Pin(("GPIO_1", 21), Pin.IN)   # create input pin on GPIO1
+
+    pin = Pin(("GPIO_1", 21), Pin.OUT, value=1)         # set pin high on creation
+
+    pin = Pin(("GPIO_1", 21), Pin.IN, Pin.PULL_UP)      # enable internal pull-up resistor
+
+    switch = Pin(("GPIO_2", 6), Pin.IN)                 # create input pin for a switch
+    switch.irq(lambda t: print("SW2 changed"))          # enable an interrupt when switch state is changed
+
+Hardware I2C bus
+----------------
+
+Hardware I2C is accessed via the :ref:`machine.I2C <machine.I2C>` class::
+
+    from machine import I2C
+
+    i2c = I2C("I2C_0")          # construct an i2c bus
+    print(i2c)                  # print device name
+
+    i2c.scan()                  # scan the device for available I2C slaves
+
+    i2c.readfrom(0x1D, 4)                # read 4 bytes from slave 0x1D
+    i2c.readfrom_mem(0x1D, 0x0D, 1)      # read 1 byte from slave 0x1D at slave memory 0x0D
+
+    i2c.writeto(0x1D, b'abcd')           # write to slave with address 0x1D
+    i2c.writeto_mem(0x1D, 0x0D, b'ab')   # write to slave 0x1D at slave memory 0x0D
+
+    buf = bytearray(8)                  # create buffer of size 8
+    i2c.writeto(0x1D, b'abcd')          # write buf to slave 0x1D
+
+Hardware SPI bus
+----------------
+
+Hardware SPI is accessed via the :ref:`machine.SPI <machine.SPI>` class::
+
+    from machine import SPI
+
+    spi = SPI("SPI_0")          # construct a spi bus with default configuration
+    spi.init(baudrate=100000, polarity=0, phase=0, bits=8, firstbit=SPI.MSB) # set configuration
+
+    # equivalently, construct spi bus and set configuration at the same time
+    spi = SPI("SPI_0", baudrate=100000, polarity=0, phase=0, bits=8, firstbit=SPI.MSB)
+    print(spi)                  # print device name and bus configuration
+
+    spi.read(4)                 # read 4 bytes on MISO
+    spi.read(4, write=0xF)      # read 4 bytes while writing 0xF on MOSI
+
+    buf = bytearray(8)          # create a buffer of size 8
+    spi.readinto(buf)           # read into the buffer (reads number of bytes equal to the buffer size)
+    spi.readinto(buf, 0xF)      # read into the buffer while writing 0xF on MOSI
+
+    spi.write(b'abcd')          # write 4 bytes on MOSI
+
+    buf = bytearray(4)                  # create buffer of size 8
+    spi.write_readinto(b'abcd', buf)    # write to MOSI and read from MISO into the buffer
+    spi.write_readinto(buf, buf)        # write buf to MOSI and read back into the buf
+
+Disk Access
+-----------
+
+Use the :ref:`zephyr.DiskAccess <zephyr.DiskAccess>` class to support filesystem::
+
+    import os
+    from zephyr import DiskAccess
+
+    block_dev = DiskAccess('SDHC')      # create a block device object for an SD card
+    os.VfsFat.mkfs(block_dev)           # create FAT filesystem object using the disk storage block
+    os.mount(block_dev, '/sd')          # mount the filesystem at the SD card subdirectory
+
+    # with the filesystem mounted, files can be manipulated as normal
+    with open('/sd/hello.txt','w') as f:     # open a new file in the directory
+        f.write('Hello world')                  # write to the file
+    print(open('/sd/hello.txt').read())      # print contents of the file
+
+Flash Area
+----------
+
+Use the :ref:`zephyr.FlashArea <zephyr.FlashArea>` class to support filesystem::
+
+    import os
+    from zephyr import FlashArea
+
+    block_dev = FlashArea(4, 4096)      # creates a block device object in the frdm-k64f flash scratch partition
+    os.VfsLfs2.mkfs(block_dev)          # create filesystem in lfs2 format using the flash block device
+    os.mount(block_dev, '/flash')       # mount the filesystem at the flash subdirectory
+
+    # with the filesystem mounted, files can be manipulated as normal
+    with open('/flash/hello.txt','w') as f:     # open a new file in the directory
+        f.write('Hello world')                  # write to the file
+    print(open('/flash/hello.txt').read())      # print contents of the file
+
+Sensor
+------
+
+Use the :ref:`zsensor.Sensor <zsensor.Sensor>` class to access sensor data::
+
+    import zsensor
+    from zsensor import Sensor
+
+    accel = Sensor("FXOX8700")    # create sensor object for the accelerometer
+
+    accel.measure()               # obtain a measurement reading from the accelerometer
+
+    # each of these prints the value taken by measure()
+    accel.float(zsensor.ACCEL_X)  # print measurement value for accelerometer X-axis sensor channel as float
+    accel.millis(zsensor.ACCEL_Y) # print measurement value for accelerometer Y-axis sensor channel in millionths
+    accel.micro(zsensor.ACCEL_Z)  # print measurement value for accelerometer Z-axis sensor channel in thousandths
+    accel.int(zsensor.ACCEL_X)    # print measurement integer value only for accelerometer X-axis sensor channel
diff --git a/docs/zephyr/tutorial/index.rst b/docs/zephyr/tutorial/index.rst
new file mode 100644
index 000000000..218156b3b
--- /dev/null
+++ b/docs/zephyr/tutorial/index.rst
@@ -0,0 +1,16 @@
+.. _zephyr_tutorial:
+
+MicroPython tutorial for the Zephyr port
+========================================
+
+This tutorial is intended to get you started with the Zephyr port.
+
+.. toctree::
+   :maxdepth: 1
+   :numbered:
+
+   intro.rst
+   repl.rst
+   storage.rst
+   pins.rst
+
diff --git a/docs/zephyr/tutorial/intro.rst b/docs/zephyr/tutorial/intro.rst
new file mode 100644
index 000000000..ffdbea8b3
--- /dev/null
+++ b/docs/zephyr/tutorial/intro.rst
@@ -0,0 +1,30 @@
+.. _intro_zephyr:
+
+Getting started with MicroPython on the Zephyr port
+===================================================
+
+Let’s get started!
+
+Requirements
+------------
+
+To use the MicroPython Zephyr port, you will need a Zephyr supported board (for a list of acceptable
+boards see :ref:`zephyr_general`).
+
+Powering up
+-----------
+
+If your board has a USB connector on it then most likely it is powered
+through this when connected to your PC. Otherwise you will need to power
+it directly. Please refer to the documentation for your board for
+further details.
+
+Getting and deploying the firmware
+----------------------------------
+
+The first step you will need to do is either clone the `MicroPython repository <https://github.com/micropython/micropython.git>`_
+or download it from the `MicroPython downloads page <http://micropython.org/download>`_. If you are an end user of MicroPython,
+it is recommended to start with the stable firmware builds. If you would like to work on development, you may follow the daily
+builds on git.
+
+Next, follow the Zephyr port readme document (``ports/zephyr/README.md``) to build and run the application on your board.
diff --git a/docs/zephyr/tutorial/pins.rst b/docs/zephyr/tutorial/pins.rst
new file mode 100644
index 000000000..8e1d6602a
--- /dev/null
+++ b/docs/zephyr/tutorial/pins.rst
@@ -0,0 +1,46 @@
+.. _pins_zephyr:
+
+GPIO Pins
+=========
+
+Use :ref:`machine.Pin <machine.Pin>` to control I/O pins.
+
+For Zephyr, pins are initialized using a tuple of port and pin number ``(\"GPIO_x\", pin#)``
+for the ``id`` value. For example to initialize a pin for the red LED on a FRDM-k64 board::
+
+        LED = Pin(("GPIO_1", 22), Pin.OUT)
+
+Reference your board's datasheet or Zephyr documentation for pin numbers, see below for more examples.
+
+.. list-table:: Pin Formatting
+   :header-rows: 1
+
+   * - Board
+     - Pin
+     - Format
+   * - frdm_k64f
+     - Red LED = PTB22
+     - ("GPIO_1", 22)
+   * - 96b_carbon
+     - LED1 = PD2
+     - ("GPIOD", 2)
+   * - mimxrt685_evk_cm33
+     - Green LED = PIO0_14
+     - ("GPIO0", 14)
+
+Interrupts
+----------
+
+The Zephyr port also supports interrupt handling for Pins using `machine.Pin.irq() <machine.Pin.irq>`.
+To respond to Pin change IRQs run::
+
+    from machine import Pin
+
+    SW2 = Pin(("GPIO_2", 6), Pin.IN)            # create Pin object for switch 2
+    SW3 = Pin(("GPIO_0", 4), Pin.IN)            # create Pin object for switch 3
+
+    SW2.irq(lambda t: print("SW2 changed"))     # print message when SW2 state is changed (triggers change IRQ)
+    SW3.irq(lambda t: print("SW3 changed"))     # print message when SW3 state is changed (triggers change IRQ)
+
+    while True:                                 # wait
+        pass
diff --git a/docs/zephyr/tutorial/repl.rst b/docs/zephyr/tutorial/repl.rst
new file mode 100644
index 000000000..a7e8955d0
--- /dev/null
+++ b/docs/zephyr/tutorial/repl.rst
@@ -0,0 +1,75 @@
+Getting a MicroPython REPL prompt
+=================================
+
+REPL stands for Read Evaluate Print Loop, and is the name given to the
+interactive MicroPython prompt that you can access on your board through
+Zephyr. It is recommended to use REPL to test out your code and run commands.
+
+REPL over the serial port
+-------------------------
+
+The REPL is available on a UART serial peripheral specified for the board by
+the ``zephyr,console`` devicetree node. The baudrate of the REPL is 115200.
+If your board has a USB-serial convertor on it then you should be able to access
+the REPL directly from your PC.
+
+To access the prompt over USB-serial you will need to use a terminal emulator
+program. For a Linux or Mac machine, open a terminal and run::
+
+        screen /dev/ttyACM0 115200
+
+You can also try ``picocom`` or ``minicom`` instead of screen. You may have to use
+``/dev/ttyACM1`` or a higher number for ``ttyACM``. Additional permissions
+may be necessary to access this device (eg group ``uucp`` or ``dialout``, or use sudo).
+For Windows, get a terminal software, such as puTTY and connect via a serial session
+using the proper COM port.
+
+Using the REPL
+--------------
+
+With your serial program open (PuTTY, screen, picocom, etc) you may see a
+blank screen with a flashing cursor. Press Enter (or reset the board) and
+you should be presented with the following text::
+
+        *** Booting Zephyr OS build v2.6.0-rc1-416-g3056c5ec30ad  ***
+        MicroPython v2.6.0-rc1-416-g3056c5ec30 on 2021-06-24; zephyr-frdm_k64f with mk64f12
+        Type "help()" for more information.
+        >>>
+
+Now you can try running MicroPython code directly on your board.
+
+Anything you type at the prompt, indicated by ``>>>``, will be executed after you press
+the Enter key. If there is an error with the text that you enter then an error
+message is printed.
+
+Start by typing the following at the prompt to make sure it is working::
+
+        >>> print("hello world!")
+        hello world!
+
+If you already know some python you can now try some basic commands here. For
+example::
+
+        >>> 1 + 2
+        3
+        >>> 1 / 2
+        0.5
+        >>> 3 * 'Zephyr'
+        ZephyrZephyrZephyr
+
+If your board has an LED, you can blink it using the following code::
+
+        >>>import time
+        >>>from machine import Pin
+
+        >>>LED = Pin(("GPIO_1", 21), Pin.OUT)
+        >>>while True:
+        ...    LED.value(1)
+        ...    time.sleep(0.5)
+        ...    LED.value(0)
+        ...    time.sleep(0.5)
+
+The above code uses an LED location for a FRDM-K64F board (port B, pin 21;
+following Zephyr conventions ports are identified by "GPIO_x", where *x*
+starts from 0). You will need to adjust it for another board using the board's
+reference materials.
diff --git a/docs/zephyr/tutorial/storage.rst b/docs/zephyr/tutorial/storage.rst
new file mode 100644
index 000000000..12bd0d0d3
--- /dev/null
+++ b/docs/zephyr/tutorial/storage.rst
@@ -0,0 +1,56 @@
+.. _storage_zephyr:
+
+Filesystems and Storage
+=======================
+
+Storage modules support virtual filesystem with FAT and littlefs formats, backed by either
+Zephyr DiskAccess or FlashArea (flash map) APIs depending on which the board supports.
+
+See `os Filesystem Mounting <https://docs.micropython.org/en/latest/library/os.html?highlight=os#filesystem-mounting>`_.
+
+Disk Access
+-----------
+
+The :ref:`zephyr.DiskAccess <zephyr.DiskAccess>` class can be used to access storage devices, such as SD cards.
+This class uses `Zephyr Disk Access API <https://docs.zephyrproject.org/latest/reference/storage/disk/access.html>`_ and
+implements the `os.AbstractBlockDev` protocol.
+
+For use with SD card controllers, SD cards must be present at boot & not removed; they will
+be auto detected and initialized by filesystem at boot. Use the disk driver interface and a
+file system to access SD cards via disk access (see below).
+
+Example usage of FatFS with an SD card on the mimxrt1050_evk board::
+
+    import os
+    from zephyr import DiskAccess
+    bdev = zephyr.DiskAccess('SDHC')        # create block device object using DiskAccess
+    os.VfsFat.mkfs(bdev)                    # create FAT filesystem object using the disk storage block
+    os.mount(bdev, '/sd')                   # mount the filesystem at the SD card subdirectory
+    with open('/sd/hello.txt','w') as f:    # open a new file in the directory
+        f.write('Hello world')              # write to the file
+    print(open('/sd/hello.txt').read())     # print contents of the file
+
+
+Flash Area
+----------
+
+The :ref:`zephyr.FlashArea <zephyr.FlashArea>` class can be used to implement a low-level storage system or
+customize filesystem configurations. To store persistent data on the device, using a higher-level filesystem
+API is recommended (see below).
+
+This class uses `Zephyr Flash map API <https://docs.zephyrproject.org/latest/reference/storage/flash_map/flash_map.html#>`_ and
+implements the `os.AbstractBlockDev` protocol.
+
+Example usage with the internal flash on the reel_board or the rv32m1_vega_ri5cy board::
+
+    import os
+    from zephyr import FlashArea
+    bdev = FlashArea(FlashArea.STORAGE, 4096)   # create block device object using FlashArea
+    os.VfsLfs2.mkfs(bdev)                       # create Little filesystem object using the flash area block
+    os.mount(bdev, '/flash')                    # mount the filesystem at the flash storage subdirectory
+    with open('/flash/hello.txt','w') as f:     # open a new file in the directory
+        f.write('Hello world')                  # write to the file
+    print(open('/flash/hello.txt').read())      # print contents of the file
+
+For boards such as the frdm_k64f in which the MicroPython application spills into the default flash storage
+partition, use the scratch partition by replacing ``FlashArea.STORAGE`` with the integer value 4.
diff --git a/drivers/cyw43/cyw43.h b/drivers/cyw43/cyw43.h
index d7f08cb5d..7d3e30f5d 100644
--- a/drivers/cyw43/cyw43.h
+++ b/drivers/cyw43/cyw43.h
@@ -28,7 +28,7 @@
 
 #include "lwip/netif.h"
 #include "lwip/dhcp.h"
-#include "lib/netutils/dhcpserver.h"
+#include "shared/netutils/dhcpserver.h"
 #include "drivers/cyw43/cyw43_ll.h"
 
 // For trace_flags
diff --git a/drivers/cyw43/cyw43_ctrl.c b/drivers/cyw43/cyw43_ctrl.c
index aaa266b0d..203bc812a 100644
--- a/drivers/cyw43/cyw43_ctrl.c
+++ b/drivers/cyw43/cyw43_ctrl.c
@@ -27,6 +27,7 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "py/mperrno.h"
 #include "py/mphal.h"
 #include "drivers/cyw43/cyw43.h"
 #include "pendsv.h"
@@ -52,6 +53,9 @@
 #define WIFI_JOIN_STATE_KEYED   (0x0800)
 #define WIFI_JOIN_STATE_ALL     (0x0e01)
 
+#define CYW43_STA_IS_ACTIVE(self) (((self)->itf_state >> CYW43_ITF_STA) & 1)
+#define CYW43_AP_IS_ACTIVE(self) (((self)->itf_state >> CYW43_ITF_AP) & 1)
+
 cyw43_t cyw43_state;
 void (*cyw43_poll)(void);
 uint32_t cyw43_sleep;
@@ -102,28 +106,25 @@ void cyw43_init(cyw43_t *self) {
 }
 
 void cyw43_deinit(cyw43_t *self) {
+    if (cyw43_poll == NULL) {
+        return;
+    }
+
     CYW_ENTER
 
-    cyw43_ll_bus_sleep(&self->cyw43_ll, true);
-    cyw43_delay_ms(2);
+    // Stop the TCP/IP network interfaces.
     cyw43_tcpip_deinit(self, 0);
     cyw43_tcpip_deinit(self, 1);
 
-    self->itf_state = 0;
-
-    // Disable async polling
+    // Turn off the SDIO bus.
+    #if USE_SDIOIT
     sdio_enable_irq(false);
-    cyw43_poll = NULL;
-
-    #ifdef pyb_pin_WL_RFSW_VDD
-    // Turn the RF-switch off
-    mp_hal_pin_low(pyb_pin_WL_RFSW_VDD);
     #endif
-
-    // Power down the WL chip and the SDIO bus
-    mp_hal_pin_low(pyb_pin_WL_REG_ON);
     sdio_deinit();
 
+    // Power off the WLAN chip and make sure all state is reset.
+    cyw43_init(self);
+
     CYW_EXIT
 }
 
@@ -478,7 +479,7 @@ void cyw43_wifi_set_up(cyw43_t *self, int itf, bool up) {
 
 int cyw43_wifi_scan(cyw43_t *self, cyw43_wifi_scan_options_t *opts, void *env, int (*result_cb)(void*, const cyw43_ev_scan_result_t*)) {
     if (self->itf_state == 0) {
-        return -1;
+        return -MP_EPERM;
     }
 
     cyw43_ensure_up(self);
@@ -521,6 +522,10 @@ int cyw43_wifi_link_status(cyw43_t *self, int itf) {
 // WiFi STA
 
 int cyw43_wifi_join(cyw43_t *self, size_t ssid_len, const uint8_t *ssid, size_t key_len, const uint8_t *key, uint32_t auth_type, const uint8_t *bssid, uint32_t channel) {
+    if (!CYW43_STA_IS_ACTIVE(self)) {
+        return -MP_EPERM;
+    }
+
     int ret = cyw43_ensure_up(self);
     if (ret) {
         return ret;
diff --git a/drivers/cyw43/cyw43_lwip.c b/drivers/cyw43/cyw43_lwip.c
index f3ca59e3a..16ae60237 100644
--- a/drivers/cyw43/cyw43_lwip.c
+++ b/drivers/cyw43/cyw43_lwip.c
@@ -28,7 +28,7 @@
 #include <string.h>
 
 #include "py/mphal.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "lwip/etharp.h"
 #include "lwip/dns.h"
 #include "lwip/apps/mdns.h"
diff --git a/drivers/neopixel/manifest.py b/drivers/neopixel/manifest.py
new file mode 100644
index 000000000..27f610adc
--- /dev/null
+++ b/drivers/neopixel/manifest.py
@@ -0,0 +1,5 @@
+freeze(
+    ".",
+    "neopixel.py",
+    opt=3,
+)
diff --git a/drivers/neopixel/neopixel.py b/drivers/neopixel/neopixel.py
new file mode 100644
index 000000000..0032d3618
--- /dev/null
+++ b/drivers/neopixel/neopixel.py
@@ -0,0 +1,46 @@
+# NeoPixel driver for MicroPython
+# MIT license; Copyright (c) 2016 Damien P. George, 2021 Jim Mussared
+
+from machine import bitstream
+
+
+class NeoPixel:
+    # G R B W
+    ORDER = (1, 0, 2, 3)
+
+    def __init__(self, pin, n, bpp=3, timing=1):
+        self.pin = pin
+        self.n = n
+        self.bpp = bpp
+        self.buf = bytearray(n * bpp)
+        self.pin.init(pin.OUT)
+        # Timing arg can either be 1 for 800kHz or 0 for 400kHz,
+        # or a user-specified timing ns tuple (high_0, low_0, high_1, low_1).
+        self.timing = (
+            ((400, 850, 800, 450) if timing else (800, 1700, 1600, 900))
+            if isinstance(timing, int)
+            else timing
+        )
+
+    def __len__(self):
+        return self.n
+
+    def __setitem__(self, i, v):
+        offset = i * self.bpp
+        for i in range(self.bpp):
+            self.buf[offset + self.ORDER[i]] = v[i]
+
+    def __getitem__(self, i):
+        offset = i * self.bpp
+        return tuple(self.buf[offset + self.ORDER[i]] for i in range(self.bpp))
+
+    def fill(self, v):
+        b = self.buf
+        for i in range(self.bpp):
+            c = v[i]
+            for j in range(self.ORDER[i], len(self.buf), self.bpp):
+                b[j] = c
+
+    def write(self):
+        # BITSTREAM_TYPE_HIGH_LOW = 0
+        bitstream(self.pin, 0, self.timing, self.buf)
diff --git a/examples/embedding/Makefile.upylib b/examples/embedding/Makefile.upylib
index 00def493d..14260a719 100644
--- a/examples/embedding/Makefile.upylib
+++ b/examples/embedding/Makefile.upylib
@@ -82,9 +82,9 @@ endif
 endif
 
 ifeq ($(MICROPY_USE_READLINE),1)
-INC +=  -I$(MPTOP)/lib/mp-readline
+INC += -I$(MPTOP)/shared/readline
 CFLAGS_MOD += -DMICROPY_USE_READLINE=1
-LIB_SRC_C_EXTRA += mp-readline/readline.c
+SHARED_SRC_C_EXTRA += readline/readline.c
 endif
 ifeq ($(MICROPY_USE_READLINE),2)
 CFLAGS_MOD += -DMICROPY_USE_READLINE=2
@@ -145,19 +145,19 @@ SRC_C = $(addprefix ports/unix/,\
 	$(SRC_MOD) \
 	)
 
-LIB_SRC_C = $(addprefix lib/,\
-	$(LIB_SRC_C_EXTRA) \
-	utils/printf.c \
-	utils/gchelper_generic.c \
+SHARED_SRC_C = $(addprefix shared/,\
+	libc/printf.c \
+	runtime/gchelper_generic.c \
 	timeutils/timeutils.c \
+	$(SHARED_SRC_C_EXTRA) \
 	)
 
 OBJ = $(PY_O)
 OBJ += $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
-OBJ += $(addprefix $(BUILD)/, $(LIB_SRC_C:.c=.o))
+OBJ += $(addprefix $(BUILD)/, $(SHARED_SRC_C:.c=.o))
 
 # List of sources for qstr extraction
-SRC_QSTR += $(SRC_C) $(LIB_SRC_C)
+SRC_QSTR += $(SRC_C) $(SHARED_SRC_C)
 # Append any auto-generated sources that are needed by sources listed in
 # SRC_QSTR
 SRC_QSTR_AUTO_DEPS +=
diff --git a/extmod/axtls-include/axtls_os_port.h b/extmod/axtls-include/axtls_os_port.h
new file mode 100644
index 000000000..ef2683acf
--- /dev/null
+++ b/extmod/axtls-include/axtls_os_port.h
@@ -0,0 +1,55 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef AXTLS_OS_PORT_H
+#define AXTLS_OS_PORT_H
+
+#include <errno.h>
+#include "py/stream.h"
+#include "lib/crypto-algorithms/sha256.h"
+
+#define SSL_CTX_MUTEX_INIT(mutex)
+#define SSL_CTX_MUTEX_DESTROY(mutex)
+#define SSL_CTX_LOCK(mutex)
+#define SSL_CTX_UNLOCK(mutex)
+
+#define SOCKET_READ(s, buf, size)       mp_stream_posix_read((void *)s, buf, size)
+#define SOCKET_WRITE(s, buf, size)      mp_stream_posix_write((void *)s, buf, size)
+#define SOCKET_CLOSE(A)                 UNUSED
+#define SOCKET_ERRNO()                  errno
+
+#define SHA256_CTX                      CRYAL_SHA256_CTX
+#define SHA256_Init(ctx)                sha256_init(ctx)
+#define SHA256_Update(ctx, buf, size)   sha256_update(ctx, buf, size)
+#define SHA256_Final(hash, ctx)         sha256_final(ctx, hash)
+
+#define TTY_FLUSH()
+
+#ifdef WDEV_HWRNG
+// For esp8266 port: use the hardware RNG.
+#define PLATFORM_RNG_U8()               (*WDEV_HWRNG)
+#endif
+
+#endif // AXTLS_OS_PORT_H
diff --git a/extmod/btstack/btstack.mk b/extmod/btstack/btstack.mk
index e65ceb04a..7ecc23000 100644
--- a/extmod/btstack/btstack.mk
+++ b/extmod/btstack/btstack.mk
@@ -67,7 +67,7 @@ endif
 LIB_SRC_C += $(SRC_BTSTACK)
 
 # Suppress some warnings.
-BTSTACK_WARNING_CFLAGS = -Wno-old-style-definition -Wno-unused-variable -Wno-unused-parameter # -Wimplicit-fallthrough=0
+BTSTACK_WARNING_CFLAGS = -Wno-old-style-definition -Wno-unused-variable -Wno-unused-parameter -Wno-implicit-fallthrough
 ifneq ($(CC),clang)
 BTSTACK_WARNING_CFLAGS += -Wno-format
 endif
diff --git a/extmod/btstack/modbluetooth_btstack.c b/extmod/btstack/modbluetooth_btstack.c
index 9c8887803..4e81e21fe 100644
--- a/extmod/btstack/modbluetooth_btstack.c
+++ b/extmod/btstack/modbluetooth_btstack.c
@@ -1085,11 +1085,14 @@ int mp_bluetooth_gatts_read(uint16_t value_handle, uint8_t **value, size_t *valu
     return mp_bluetooth_gatts_db_read(MP_STATE_PORT(bluetooth_btstack_root_pointers)->gatts_db, value_handle, value, value_len);
 }
 
-int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len) {
+int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len, bool send_update) {
     DEBUG_printf("mp_bluetooth_gatts_write\n");
     if (!mp_bluetooth_is_active()) {
         return ERRNO_BLUETOOTH_NOT_ACTIVE;
     }
+    if (send_update) {
+        return MP_EOPNOTSUPP;
+    }
     return mp_bluetooth_gatts_db_write(MP_STATE_PORT(bluetooth_btstack_root_pointers)->gatts_db, value_handle, value, value_len);
 }
 
diff --git a/extmod/extmod.cmake b/extmod/extmod.cmake
index a54047519..c6b45b0d3 100644
--- a/extmod/extmod.cmake
+++ b/extmod/extmod.cmake
@@ -4,8 +4,9 @@ set(MICROPY_EXTMOD_DIR "${MICROPY_DIR}/extmod")
 set(MICROPY_OOFATFS_DIR "${MICROPY_DIR}/lib/oofatfs")
 
 set(MICROPY_SOURCE_EXTMOD
-    ${MICROPY_DIR}/lib/embed/abort_.c
-    ${MICROPY_DIR}/lib/utils/printf.c
+    ${MICROPY_DIR}/shared/libc/abort_.c
+    ${MICROPY_DIR}/shared/libc/printf.c
+    ${MICROPY_EXTMOD_DIR}/machine_bitstream.c
     ${MICROPY_EXTMOD_DIR}/machine_i2c.c
     ${MICROPY_EXTMOD_DIR}/machine_mem.c
     ${MICROPY_EXTMOD_DIR}/machine_pulse.c
diff --git a/extmod/extmod.mk b/extmod/extmod.mk
index b000b058d..ff24a549a 100644
--- a/extmod/extmod.mk
+++ b/extmod/extmod.mk
@@ -153,7 +153,7 @@ LWIP_DIR = lib/lwip/src
 INC += -I$(TOP)/$(LWIP_DIR)/include
 CFLAGS_MOD += -DMICROPY_PY_LWIP=1
 $(BUILD)/$(LWIP_DIR)/core/ipv4/dhcp.o: CFLAGS_MOD += -Wno-address
-SRC_MOD += extmod/modlwip.c lib/netutils/netutils.c
+SRC_MOD += extmod/modlwip.c shared/netutils/netutils.c
 SRC_MOD += $(addprefix $(LWIP_DIR)/,\
 	apps/mdns/mdns.c \
 	core/def.c \
diff --git a/extmod/machine_bitstream.c b/extmod/machine_bitstream.c
new file mode 100644
index 000000000..30f1ff1ea
--- /dev/null
+++ b/extmod/machine_bitstream.c
@@ -0,0 +1,65 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Jim Mussared
+ * Copyright (c) 2021 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "extmod/machine_bitstream.h"
+
+#if MICROPY_PY_MACHINE_BITSTREAM
+
+// Timing is a 4-tuple of (high_time_0, low_time_0, high_time_1, low_time_1)
+// suitable for driving WS2812.
+#define MICROPY_MACHINE_BITSTREAM_TYPE_HIGH_LOW (0)
+
+// machine.bitstream(pin, encoding, (timing), bytes)
+STATIC mp_obj_t machine_bitstream_(size_t n_args, const mp_obj_t *args) {
+    mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(args[0]);
+    int encoding = mp_obj_get_int(args[1]);
+
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(args[3], &bufinfo, MP_BUFFER_READ);
+
+    switch (encoding) {
+        case MICROPY_MACHINE_BITSTREAM_TYPE_HIGH_LOW: {
+            uint32_t timing_ns[4];
+            mp_obj_t *timing;
+            mp_obj_get_array_fixed_n(args[2], 4, &timing);
+            for (size_t i = 0; i < 4; ++i) {
+                timing_ns[i] = mp_obj_get_int(timing[i]);
+            }
+            machine_bitstream_high_low(pin, timing_ns, bufinfo.buf, bufinfo.len);
+            break;
+        }
+        default:
+            mp_raise_ValueError(MP_ERROR_TEXT("encoding"));
+    }
+
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(machine_bitstream_obj, 4, 4, machine_bitstream_);
+
+#endif // MICROPY_PY_MACHINE_BITSTREAM
diff --git a/extmod/machine_bitstream.h b/extmod/machine_bitstream.h
new file mode 100644
index 000000000..2e759aedd
--- /dev/null
+++ b/extmod/machine_bitstream.h
@@ -0,0 +1,37 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Jim Mussared
+ * Copyright (c) 2021 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_EXTMOD_MACHINE_BITSTREAM_H
+#define MICROPY_INCLUDED_EXTMOD_MACHINE_BITSTREAM_H
+
+#include "py/obj.h"
+#include "py/mphal.h"
+
+void machine_bitstream_high_low(mp_hal_pin_obj_t pin, uint32_t *timing_ns, const uint8_t *buf, size_t len);
+
+MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(machine_bitstream_obj);
+
+#endif // MICROPY_INCLUDED_EXTMOD_MACHINE_BITSTREAM_H
diff --git a/extmod/modbluetooth.c b/extmod/modbluetooth.c
index e379a8c6a..cb153f70e 100644
--- a/extmod/modbluetooth.c
+++ b/extmod/modbluetooth.c
@@ -717,15 +717,17 @@ STATIC mp_obj_t bluetooth_ble_gatts_read(mp_obj_t self_in, mp_obj_t value_handle
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(bluetooth_ble_gatts_read_obj, bluetooth_ble_gatts_read);
 
-STATIC mp_obj_t bluetooth_ble_gatts_write(mp_obj_t self_in, mp_obj_t value_handle_in, mp_obj_t data) {
-    (void)self_in;
+STATIC mp_obj_t bluetooth_ble_gatts_write(size_t n_args, const mp_obj_t *args) {
     mp_buffer_info_t bufinfo = {0};
-    mp_get_buffer_raise(data, &bufinfo, MP_BUFFER_READ);
-    int err = mp_bluetooth_gatts_write(mp_obj_get_int(value_handle_in), bufinfo.buf, bufinfo.len);
-    bluetooth_handle_errno(err);
+    mp_get_buffer_raise(args[2], &bufinfo, MP_BUFFER_READ);
+    bool send_update = false;
+    if (n_args > 3) {
+        send_update = mp_obj_is_true(args[3]);
+    }
+    bluetooth_handle_errno(mp_bluetooth_gatts_write(mp_obj_get_int(args[1]), bufinfo.buf, bufinfo.len, send_update));
     return MP_OBJ_NEW_SMALL_INT(bufinfo.len);
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_3(bluetooth_ble_gatts_write_obj, bluetooth_ble_gatts_write);
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gatts_write_obj, 3, 4, bluetooth_ble_gatts_write);
 
 STATIC mp_obj_t bluetooth_ble_gatts_notify(size_t n_args, const mp_obj_t *args) {
     mp_int_t conn_handle = mp_obj_get_int(args[1]);
@@ -842,7 +844,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(bluetooth_ble_gattc_exchange_mtu_obj, bluetooth
 STATIC mp_obj_t bluetooth_ble_l2cap_listen(mp_obj_t self_in, mp_obj_t psm_in, mp_obj_t mtu_in) {
     (void)self_in;
     mp_int_t psm = mp_obj_get_int(psm_in);
-    mp_int_t mtu = mp_obj_get_int(mtu_in);
+    mp_int_t mtu = MAX(32, MIN(UINT16_MAX, mp_obj_get_int(mtu_in)));
     return bluetooth_handle_errno(mp_bluetooth_l2cap_listen(psm, mtu));
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_3(bluetooth_ble_l2cap_listen_obj, bluetooth_ble_l2cap_listen);
@@ -850,7 +852,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_3(bluetooth_ble_l2cap_listen_obj, bluetooth_ble_l
 STATIC mp_obj_t bluetooth_ble_l2cap_connect(size_t n_args, const mp_obj_t *args) {
     mp_int_t conn_handle = mp_obj_get_int(args[1]);
     mp_int_t psm = mp_obj_get_int(args[2]);
-    mp_int_t mtu = mp_obj_get_int(args[3]);
+    mp_int_t mtu = MAX(32, MIN(UINT16_MAX, mp_obj_get_int(args[3])));
     return bluetooth_handle_errno(mp_bluetooth_l2cap_connect(conn_handle, psm, mtu));
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_l2cap_connect_obj, 4, 4, bluetooth_ble_l2cap_connect);
diff --git a/extmod/modbluetooth.h b/extmod/modbluetooth.h
index d126ad6c1..43519e594 100644
--- a/extmod/modbluetooth.h
+++ b/extmod/modbluetooth.h
@@ -334,8 +334,8 @@ int mp_bluetooth_gatts_register_service_end(void);
 
 // Read the value from the local gatts db (likely this has been written by a central).
 int mp_bluetooth_gatts_read(uint16_t value_handle, uint8_t **value, size_t *value_len);
-// Write a value to the local gatts db (ready to be queried by a central).
-int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len);
+// Write a value to the local gatts db (ready to be queried by a central). Optionally send notifications/indications.
+int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len, bool send_update);
 // Notify the central that it should do a read.
 int mp_bluetooth_gatts_notify(uint16_t conn_handle, uint16_t value_handle);
 // Notify the central, including a data payload. (Note: does not set the gatts db value).
diff --git a/extmod/modframebuf.c b/extmod/modframebuf.c
index 18b170078..454624dda 100644
--- a/extmod/modframebuf.c
+++ b/extmod/modframebuf.c
@@ -491,6 +491,10 @@ STATIC mp_obj_t framebuf_blit(size_t n_args, const mp_obj_t *args) {
     if (n_args > 4) {
         key = mp_obj_get_int(args[4]);
     }
+    mp_obj_framebuf_t *palette = NULL;
+    if (n_args > 5 && args[5] != mp_const_none) {
+        palette = MP_OBJ_TO_PTR(mp_obj_cast_to_native_base(args[5], MP_OBJ_FROM_PTR(&mp_type_framebuf)));
+    }
 
     if (
         (x >= self->width) ||
@@ -514,6 +518,9 @@ STATIC mp_obj_t framebuf_blit(size_t n_args, const mp_obj_t *args) {
         int cx1 = x1;
         for (int cx0 = x0; cx0 < x0end; ++cx0) {
             uint32_t col = getpixel(source, cx1, y1);
+            if (palette) {
+                col = getpixel(palette, col, 0);
+            }
             if (col != (uint32_t)key) {
                 setpixel(self, cx0, y0, col);
             }
@@ -523,7 +530,7 @@ STATIC mp_obj_t framebuf_blit(size_t n_args, const mp_obj_t *args) {
     }
     return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(framebuf_blit_obj, 4, 5, framebuf_blit);
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(framebuf_blit_obj, 4, 6, framebuf_blit);
 
 STATIC mp_obj_t framebuf_scroll(mp_obj_t self_in, mp_obj_t xstep_in, mp_obj_t ystep_in) {
     mp_obj_framebuf_t *self = MP_OBJ_TO_PTR(self_in);
diff --git a/extmod/modlwip.c b/extmod/modlwip.c
index 1d557a6a8..8811742d6 100644
--- a/extmod/modlwip.c
+++ b/extmod/modlwip.c
@@ -35,7 +35,7 @@
 #include "py/mperrno.h"
 #include "py/mphal.h"
 
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 
 #include "lwip/init.h"
 #include "lwip/tcp.h"
@@ -1502,16 +1502,16 @@ STATIC mp_uint_t lwip_socket_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_
             return 0;
         }
 
-        // Deregister callback (pcb.tcp is set to NULL below so must deregister now)
-        tcp_arg(socket->pcb.tcp, NULL);
-        tcp_err(socket->pcb.tcp, NULL);
-        tcp_recv(socket->pcb.tcp, NULL);
-
         // Free any incoming buffers or connections that are stored
         lwip_socket_free_incoming(socket);
 
         switch (socket->type) {
             case MOD_NETWORK_SOCK_STREAM: {
+                // Deregister callback (pcb.tcp is set to NULL below so must deregister now)
+                tcp_arg(socket->pcb.tcp, NULL);
+                tcp_err(socket->pcb.tcp, NULL);
+                tcp_recv(socket->pcb.tcp, NULL);
+
                 if (socket->pcb.tcp->state != LISTEN) {
                     // Schedule a callback to abort the connection if it's not cleanly closed after
                     // the given timeout.  The callback must be set before calling tcp_close since
@@ -1525,10 +1525,12 @@ STATIC mp_uint_t lwip_socket_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_
                 break;
             }
             case MOD_NETWORK_SOCK_DGRAM:
+                udp_recv(socket->pcb.udp, NULL, NULL);
                 udp_remove(socket->pcb.udp);
                 break;
             #if MICROPY_PY_LWIP_SOCK_RAW
             case MOD_NETWORK_SOCK_RAW:
+                raw_recv(socket->pcb.raw, NULL, NULL);
                 raw_remove(socket->pcb.raw);
                 break;
             #endif
diff --git a/extmod/modubinascii.c b/extmod/modubinascii.c
index 9e4f86fbd..fab7717c4 100644
--- a/extmod/modubinascii.c
+++ b/extmod/modubinascii.c
@@ -218,7 +218,7 @@ STATIC mp_obj_t mod_binascii_b2a_base64(mp_obj_t data) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_binascii_b2a_base64_obj, mod_binascii_b2a_base64);
 
 #if MICROPY_PY_UBINASCII_CRC32
-#include "uzlib/tinf.h"
+#include "lib/uzlib/tinf.h"
 
 STATIC mp_obj_t mod_binascii_crc32(size_t n_args, const mp_obj_t *args) {
     mp_buffer_info_t bufinfo;
diff --git a/extmod/moduhashlib.c b/extmod/moduhashlib.c
index b170de9e5..e97e8cb75 100644
--- a/extmod/moduhashlib.c
+++ b/extmod/moduhashlib.c
@@ -40,7 +40,7 @@
 #if MICROPY_SSL_MBEDTLS
 #include "mbedtls/sha256.h"
 #else
-#include "crypto-algorithms/sha256.h"
+#include "lib/crypto-algorithms/sha256.h"
 #endif
 
 #endif
@@ -115,7 +115,7 @@ STATIC mp_obj_t uhashlib_sha256_digest(mp_obj_t self_in) {
 
 #else
 
-#include "crypto-algorithms/sha256.c"
+#include "lib/crypto-algorithms/sha256.c"
 
 STATIC mp_obj_t uhashlib_sha256_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_check_num(n_args, n_kw, 0, 1, false);
diff --git a/extmod/modujson.c b/extmod/modujson.c
index 8dff67358..e5bfb0d96 100644
--- a/extmod/modujson.c
+++ b/extmod/modujson.c
@@ -34,6 +34,62 @@
 
 #if MICROPY_PY_UJSON
 
+#if MICROPY_PY_UJSON_SEPARATORS
+
+enum {
+    DUMP_MODE_TO_STRING = 1,
+    DUMP_MODE_TO_STREAM = 2,
+};
+
+STATIC mp_obj_t mod_ujson_dump_helper(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args, unsigned int mode) {
+    enum { ARG_separators };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_separators, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+    };
+
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args - mode, pos_args + mode, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    mp_print_ext_t print_ext;
+
+    if (args[ARG_separators].u_obj == mp_const_none) {
+        print_ext.item_separator = ", ";
+        print_ext.key_separator = ": ";
+    } else {
+        mp_obj_t *items;
+        mp_obj_get_array_fixed_n(args[ARG_separators].u_obj, 2, &items);
+        print_ext.item_separator = mp_obj_str_get_str(items[0]);
+        print_ext.key_separator = mp_obj_str_get_str(items[1]);
+    }
+
+    if (mode == DUMP_MODE_TO_STRING) {
+        // dumps(obj)
+        vstr_t vstr;
+        vstr_init_print(&vstr, 8, &print_ext.base);
+        mp_obj_print_helper(&print_ext.base, pos_args[0], PRINT_JSON);
+        return mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
+    } else {
+        // dump(obj, stream)
+        print_ext.base.data = MP_OBJ_TO_PTR(pos_args[1]);
+        print_ext.base.print_strn = mp_stream_write_adaptor;
+        mp_get_stream_raise(pos_args[1], MP_STREAM_OP_WRITE);
+        mp_obj_print_helper(&print_ext.base, pos_args[0], PRINT_JSON);
+        return mp_const_none;
+    }
+}
+
+STATIC mp_obj_t mod_ujson_dump(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    return mod_ujson_dump_helper(n_args, pos_args, kw_args, DUMP_MODE_TO_STREAM);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(mod_ujson_dump_obj, 2, mod_ujson_dump);
+
+STATIC mp_obj_t mod_ujson_dumps(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    return mod_ujson_dump_helper(n_args, pos_args, kw_args, DUMP_MODE_TO_STRING);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(mod_ujson_dumps_obj, 1, mod_ujson_dumps);
+
+#else
+
 STATIC mp_obj_t mod_ujson_dump(mp_obj_t obj, mp_obj_t stream) {
     mp_get_stream_raise(stream, MP_STREAM_OP_WRITE);
     mp_print_t print = {MP_OBJ_TO_PTR(stream), mp_stream_write_adaptor};
@@ -51,6 +107,8 @@ STATIC mp_obj_t mod_ujson_dumps(mp_obj_t obj) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_dumps_obj, mod_ujson_dumps);
 
+#endif
+
 // The function below implements a simple non-recursive JSON parser.
 //
 // The JSON specification is at http://www.ietf.org/rfc/rfc4627.txt
diff --git a/extmod/modure.c b/extmod/modure.c
index 220587b42..738a2b984 100644
--- a/extmod/modure.c
+++ b/extmod/modure.c
@@ -37,7 +37,7 @@
 
 #define re1_5_stack_chk() MP_STACK_CHECK()
 
-#include "re1.5/re1.5.h"
+#include "lib/re1.5/re1.5.h"
 
 #define FLAG_DEBUG 0x1000
 
@@ -68,7 +68,7 @@ STATIC mp_obj_t match_group(mp_obj_t self_in, mp_obj_t no_in) {
     mp_obj_match_t *self = MP_OBJ_TO_PTR(self_in);
     mp_int_t no = mp_obj_get_int(no_in);
     if (no < 0 || no >= self->num_matches) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_IndexError, no_in));
+        mp_raise_type_arg(&mp_type_IndexError, no_in);
     }
 
     const char *start = self->caps[no * 2];
@@ -107,7 +107,7 @@ STATIC void match_span_helper(size_t n_args, const mp_obj_t *args, mp_obj_t span
     if (n_args == 2) {
         no = mp_obj_get_int(args[1]);
         if (no < 0 || no >= self->num_matches) {
-            nlr_raise(mp_obj_new_exception_arg1(&mp_type_IndexError, args[1]));
+            mp_raise_type_arg(&mp_type_IndexError, args[1]);
         }
     }
 
@@ -334,7 +334,7 @@ STATIC mp_obj_t re_sub_helper(size_t n_args, const mp_obj_t *args) {
                     }
 
                     if (match_no >= (unsigned int)match->num_matches) {
-                        nlr_raise(mp_obj_new_exception_arg1(&mp_type_IndexError, MP_OBJ_NEW_SMALL_INT(match_no)));
+                        mp_raise_type_arg(&mp_type_IndexError, MP_OBJ_NEW_SMALL_INT(match_no));
                     }
 
                     const char *start_match = match->caps[match_no * 2];
@@ -454,11 +454,11 @@ const mp_obj_module_t mp_module_ure = {
 // only if module is enabled by config setting.
 
 #define re1_5_fatal(x) assert(!x)
-#include "re1.5/compilecode.c"
+#include "lib/re1.5/compilecode.c"
 #if MICROPY_PY_URE_DEBUG
-#include "re1.5/dumpcode.c"
+#include "lib/re1.5/dumpcode.c"
 #endif
-#include "re1.5/recursiveloop.c"
-#include "re1.5/charclass.c"
+#include "lib/re1.5/recursiveloop.c"
+#include "lib/re1.5/charclass.c"
 
 #endif // MICROPY_PY_URE
diff --git a/extmod/moduselect.c b/extmod/moduselect.c
index fbd51960d..cf47f02af 100644
--- a/extmod/moduselect.c
+++ b/extmod/moduselect.c
@@ -107,6 +107,7 @@ STATIC mp_uint_t poll_map_poll(mp_map_t *poll_map, size_t *rwx_num) {
     return n_ready;
 }
 
+#if MICROPY_PY_USELECT_SELECT
 // select(rlist, wlist, xlist[, timeout])
 STATIC mp_obj_t select_select(size_t n_args, const mp_obj_t *args) {
     // get array data from tuple/list arguments
@@ -173,6 +174,7 @@ STATIC mp_obj_t select_select(size_t n_args, const mp_obj_t *args) {
     }
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_select_select_obj, 3, 4, select_select);
+#endif // MICROPY_PY_USELECT_SELECT
 
 typedef struct _mp_obj_poll_t {
     mp_obj_base_t base;
@@ -355,7 +357,9 @@ MP_DEFINE_CONST_FUN_OBJ_0(mp_select_poll_obj, select_poll);
 
 STATIC const mp_rom_map_elem_t mp_module_select_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_uselect) },
+    #if MICROPY_PY_USELECT_SELECT
     { MP_ROM_QSTR(MP_QSTR_select), MP_ROM_PTR(&mp_select_select_obj) },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_poll), MP_ROM_PTR(&mp_select_poll_obj) },
     { MP_ROM_QSTR(MP_QSTR_POLLIN), MP_ROM_INT(MP_STREAM_POLL_RD) },
     { MP_ROM_QSTR(MP_QSTR_POLLOUT), MP_ROM_INT(MP_STREAM_POLL_WR) },
diff --git a/extmod/moduzlib.c b/extmod/moduzlib.c
index ab70d6747..f78c34908 100644
--- a/extmod/moduzlib.c
+++ b/extmod/moduzlib.c
@@ -33,7 +33,7 @@
 
 #if MICROPY_PY_UZLIB
 
-#include "uzlib/tinf.h"
+#include "lib/uzlib/tinf.h"
 
 #if 0 // print debugging info
 #define DEBUG_printf DEBUG_printf
@@ -201,7 +201,7 @@ STATIC mp_obj_t mod_uzlib_decompress(size_t n_args, const mp_obj_t *args) {
     return res;
 
 error:
-    nlr_raise(mp_obj_new_exception_arg1(&mp_type_ValueError, MP_OBJ_NEW_SMALL_INT(st)));
+    mp_raise_type_arg(&mp_type_ValueError, MP_OBJ_NEW_SMALL_INT(st));
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_uzlib_decompress_obj, 1, 3, mod_uzlib_decompress);
 
@@ -223,10 +223,10 @@ const mp_obj_module_t mp_module_uzlib = {
 // Source files #include'd here to make sure they're compiled in
 // only if module is enabled by config setting.
 
-#include "uzlib/tinflate.c"
-#include "uzlib/tinfzlib.c"
-#include "uzlib/tinfgzip.c"
-#include "uzlib/adler32.c"
-#include "uzlib/crc32.c"
+#include "lib/uzlib/tinflate.c"
+#include "lib/uzlib/tinfzlib.c"
+#include "lib/uzlib/tinfgzip.c"
+#include "lib/uzlib/adler32.c"
+#include "lib/uzlib/crc32.c"
 
 #endif // MICROPY_PY_UZLIB
diff --git a/extmod/network_cyw43.c b/extmod/network_cyw43.c
index adbe427b1..a5ed5d5b8 100644
--- a/extmod/network_cyw43.c
+++ b/extmod/network_cyw43.c
@@ -196,7 +196,7 @@ STATIC mp_obj_t network_cyw43_scan(size_t n_args, const mp_obj_t *pos_args, mp_m
     int scan_res = cyw43_wifi_scan(self->cyw, &opts, MP_OBJ_TO_PTR(res), network_cyw43_scan_cb);
 
     if (scan_res < 0) {
-        mp_raise_msg(&mp_type_OSError, MP_ERROR_TEXT("STA must be active"));
+        mp_raise_OSError(-scan_res);
     }
 
     // Wait for scan to finish, with a 10s timeout
@@ -240,7 +240,7 @@ STATIC mp_obj_t network_cyw43_connect(size_t n_args, const mp_obj_t *pos_args, m
     }
     int ret = cyw43_wifi_join(self->cyw, ssid.len, ssid.buf, key.len, key.buf, args[ARG_auth].u_int, bssid.buf, args[ARG_channel].u_int);
     if (ret != 0) {
-        mp_raise_OSError(ret);
+        mp_raise_OSError(-ret);
     }
     return mp_const_none;
 }
diff --git a/extmod/nimble/hal/hal_uart.c b/extmod/nimble/hal/hal_uart.c
index cd5e49e30..84a964fde 100644
--- a/extmod/nimble/hal/hal_uart.c
+++ b/extmod/nimble/hal/hal_uart.c
@@ -27,6 +27,7 @@
 #include "py/runtime.h"
 #include "py/mphal.h"
 #include "nimble/ble.h"
+#include "extmod/nimble/modbluetooth_nimble.h"
 #include "extmod/nimble/hal/hal_uart.h"
 #include "extmod/nimble/nimble/nimble_npl_os.h"
 #include "extmod/mpbthci.h"
@@ -74,6 +75,11 @@ void hal_uart_start_tx(uint32_t port) {
     #endif
 
     mp_bluetooth_hci_uart_write(mp_bluetooth_hci_cmd_buf, len);
+
+    if (len > 0) {
+        // Allow modbluetooth bindings to hook "sent packet" (e.g. to unstall l2cap channels).
+        mp_bluetooth_nimble_sent_hci_packet();
+    }
 }
 
 int hal_uart_close(uint32_t port) {
diff --git a/extmod/nimble/modbluetooth_nimble.c b/extmod/nimble/modbluetooth_nimble.c
index f4b9ccb60..e4b4cb68a 100644
--- a/extmod/nimble/modbluetooth_nimble.c
+++ b/extmod/nimble/modbluetooth_nimble.c
@@ -512,6 +512,11 @@ STATIC int central_gap_event_cb(struct ble_gap_event *event, void *arg) {
 
             return 0;
         }
+
+        case BLE_GAP_EVENT_SUBSCRIBE: {
+            DEBUG_printf("central_gap_event_cb: subscribe: handle=%d, reason=%d notify=%d indicate=%d \n", event->subscribe.attr_handle, event->subscribe.reason, event->subscribe.cur_notify, event->subscribe.cur_indicate);
+            return 0;
+        }
     }
 
     return commmon_gap_event_cb(event, arg);
@@ -1004,11 +1009,15 @@ int mp_bluetooth_gatts_read(uint16_t value_handle, uint8_t **value, size_t *valu
     return mp_bluetooth_gatts_db_read(MP_STATE_PORT(bluetooth_nimble_root_pointers)->gatts_db, value_handle, value, value_len);
 }
 
-int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len) {
+int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len, bool send_update) {
     if (!mp_bluetooth_is_active()) {
         return ERRNO_BLUETOOTH_NOT_ACTIVE;
     }
-    return mp_bluetooth_gatts_db_write(MP_STATE_PORT(bluetooth_nimble_root_pointers)->gatts_db, value_handle, value, value_len);
+    int err = mp_bluetooth_gatts_db_write(MP_STATE_PORT(bluetooth_nimble_root_pointers)->gatts_db, value_handle, value, value_len);
+    if (err == 0 && send_update) {
+        ble_gatts_chr_updated(value_handle);
+    }
+    return err;
 }
 
 // TODO: Could use ble_gatts_chr_updated to send to all subscribed centrals.
@@ -1392,6 +1401,18 @@ int mp_bluetooth_gattc_exchange_mtu(uint16_t conn_handle) {
 
 #endif // MICROPY_PY_BLUETOOTH_ENABLE_GATT_CLIENT
 
+#if MICROPY_PY_BLUETOOTH_ENABLE_L2CAP_CHANNELS
+STATIC void unstall_l2cap_channel(void);
+#endif
+
+void mp_bluetooth_nimble_sent_hci_packet(void) {
+    #if MICROPY_PY_BLUETOOTH_ENABLE_L2CAP_CHANNELS
+    if (os_msys_num_free() >= os_msys_count() * 3 / 4) {
+        unstall_l2cap_channel();
+    }
+    #endif
+}
+
 #if MICROPY_PY_BLUETOOTH_ENABLE_L2CAP_CHANNELS
 
 // Fortunately NimBLE uses mbuf chains correctly with L2CAP COC (rather than
@@ -1413,6 +1434,7 @@ typedef struct _mp_bluetooth_nimble_l2cap_channel_t {
     struct os_mempool sdu_mempool;
     struct os_mbuf *rx_pending;
     bool irq_in_progress;
+    bool mem_stalled;
     uint16_t mtu;
     os_membuf_t sdu_mem[];
 } mp_bluetooth_nimble_l2cap_channel_t;
@@ -1430,6 +1452,19 @@ STATIC void destroy_l2cap_channel() {
     }
 }
 
+STATIC void unstall_l2cap_channel(void) {
+    // Whenever we send an HCI packet and the sys mempool is now less than 1/4 full,
+    // we can unstall the L2CAP channel if it was marked as "mem_stalled" by
+    // mp_bluetooth_l2cap_send. (This happens if the pool is half-empty).
+    mp_bluetooth_nimble_l2cap_channel_t *chan = MP_STATE_PORT(bluetooth_nimble_root_pointers)->l2cap_chan;
+    if (!chan || !chan->mem_stalled) {
+        return;
+    }
+    DEBUG_printf("unstall_l2cap_channel: count %d, free: %d\n", os_msys_count(), os_msys_num_free());
+    chan->mem_stalled = false;
+    mp_bluetooth_on_l2cap_send_ready(chan->chan->conn_handle, chan->chan->scid, 0);
+}
+
 STATIC int l2cap_channel_event(struct ble_l2cap_event *event, void *arg) {
     DEBUG_printf("l2cap_channel_event: type=%d\n", event->type);
     mp_bluetooth_nimble_l2cap_channel_t *chan = (mp_bluetooth_nimble_l2cap_channel_t *)arg;
@@ -1525,9 +1560,13 @@ STATIC int l2cap_channel_event(struct ble_l2cap_event *event, void *arg) {
         }
         case BLE_L2CAP_EVENT_COC_TX_UNSTALLED: {
             DEBUG_printf("l2cap_channel_event: tx_unstalled: conn_handle=%d status=%d\n", event->tx_unstalled.conn_handle, event->tx_unstalled.status);
-            ble_l2cap_get_chan_info(event->receive.chan, &info);
-            // Map status to {0,1} (i.e. "sent everything", or "partial send").
-            mp_bluetooth_on_l2cap_send_ready(event->tx_unstalled.conn_handle, info.scid, event->tx_unstalled.status == 0 ? 0 : 1);
+            assert(event->tx_unstalled.conn_handle == chan->chan->conn_handle);
+            // Don't unstall if we're still waiting for room in the sys pool.
+            if (!chan->mem_stalled) {
+                ble_l2cap_get_chan_info(event->receive.chan, &info);
+                // Map status to {0,1} (i.e. "sent everything", or "partial send").
+                mp_bluetooth_on_l2cap_send_ready(event->tx_unstalled.conn_handle, info.scid, event->tx_unstalled.status == 0 ? 0 : 1);
+            }
             break;
         }
         case BLE_L2CAP_EVENT_COC_RECONFIG_COMPLETED: {
@@ -1675,14 +1714,35 @@ int mp_bluetooth_l2cap_send(uint16_t conn_handle, uint16_t cid, const uint8_t *b
         return MP_ENOMEM;
     }
 
+    *stalled = false;
+
     err = ble_l2cap_send(chan->chan, sdu_tx);
     if (err == BLE_HS_ESTALLED) {
         // Stalled means that this one will still send but any future ones
         // will fail until we receive an unstalled event.
+        DEBUG_printf("mp_bluetooth_l2cap_send: credit stall\n");
         *stalled = true;
         err = 0;
     } else {
-        *stalled = false;
+        if (err) {
+            // Anything except stalled means it won't attempt to send,
+            // so free the mbuf (we're failing the op entirely).
+            os_mbuf_free_chain(sdu_tx);
+        }
+    }
+
+    if (os_msys_num_free() <= os_msys_count() / 2) {
+        // If the sys mempool is less than half-full, then back off sending more
+        // on this channel.
+        DEBUG_printf("mp_bluetooth_l2cap_send: forcing mem stall: count %d, free: %d\n", os_msys_count(), os_msys_num_free());
+        chan->mem_stalled = true;
+        *stalled = true;
+    }
+
+    // Sometimes we see what looks like BLE_HS_EAGAIN (but it's actually
+    // OS_ENOMEM in disguise). Fixed in NimBLE v1.4.
+    if (err == OS_ENOMEM) {
+        err = BLE_HS_ENOMEM;
     }
 
     // Other error codes such as BLE_HS_EBUSY (we're stalled) or BLE_HS_EBADDATA (bigger than MTU).
diff --git a/extmod/nimble/modbluetooth_nimble.h b/extmod/nimble/modbluetooth_nimble.h
index 9ed64368b..15648a995 100644
--- a/extmod/nimble/modbluetooth_nimble.h
+++ b/extmod/nimble/modbluetooth_nimble.h
@@ -71,5 +71,8 @@ void mp_bluetooth_nimble_port_start(void);
 // Tell the port to stop its background task.
 void mp_bluetooth_nimble_port_shutdown(void);
 
+// --- Called by the HCI UART layer to let us know when packets have been sent.
+void mp_bluetooth_nimble_sent_hci_packet(void);
+
 
 #endif // MICROPY_INCLUDED_EXTMOD_NIMBLE_MODBLUETOOTH_NIMBLE_H
diff --git a/extmod/uasyncio/stream.py b/extmod/uasyncio/stream.py
index 8de2d2599..af3b8feab 100644
--- a/extmod/uasyncio/stream.py
+++ b/extmod/uasyncio/stream.py
@@ -79,8 +79,8 @@ async def open_connection(host, port):
     from uerrno import EINPROGRESS
     import usocket as socket
 
-    ai = socket.getaddrinfo(host, port)[0]  # TODO this is blocking!
-    s = socket.socket()
+    ai = socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM)[0]  # TODO this is blocking!
+    s = socket.socket(ai[0], ai[1], ai[2])
     s.setblocking(False)
     ss = Stream(s)
     try:
diff --git a/extmod/uos_dupterm.c b/extmod/uos_dupterm.c
index b66180387..d55767de2 100644
--- a/extmod/uos_dupterm.c
+++ b/extmod/uos_dupterm.c
@@ -33,7 +33,7 @@
 #include "py/objarray.h"
 #include "py/stream.h"
 #include "extmod/misc.h"
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 
 #if MICROPY_PY_OS_DUPTERM
 
diff --git a/extmod/utime_mphal.c b/extmod/utime_mphal.c
index d053cf128..3d1cdfd82 100644
--- a/extmod/utime_mphal.c
+++ b/extmod/utime_mphal.c
@@ -48,7 +48,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(mp_utime_sleep_obj, time_sleep);
 
 STATIC mp_obj_t time_sleep_ms(mp_obj_t arg) {
     mp_int_t ms = mp_obj_get_int(arg);
-    if (ms > 0) {
+    if (ms >= 0) {
         mp_hal_delay_ms(ms);
     }
     return mp_const_none;
diff --git a/extmod/vfs_fat.c b/extmod/vfs_fat.c
index 644be57ae..41284500b 100644
--- a/extmod/vfs_fat.c
+++ b/extmod/vfs_fat.c
@@ -37,7 +37,7 @@
 #include "py/mperrno.h"
 #include "lib/oofatfs/ff.h"
 #include "extmod/vfs_fat.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 
 #if FF_MAX_SS == FF_MIN_SS
 #define SECSIZE(fs) (FF_MIN_SS)
diff --git a/extmod/vfs_lfs.c b/extmod/vfs_lfs.c
index dd78269a4..f6a9a2462 100644
--- a/extmod/vfs_lfs.c
+++ b/extmod/vfs_lfs.c
@@ -26,7 +26,7 @@
 
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "extmod/vfs.h"
 #include "extmod/vfs_lfs.h"
 
diff --git a/extmod/vfs_lfsx.c b/extmod/vfs_lfsx.c
index f865e4606..e1324f82c 100644
--- a/extmod/vfs_lfsx.c
+++ b/extmod/vfs_lfsx.c
@@ -34,7 +34,7 @@
 #include "py/objstr.h"
 #include "py/mperrno.h"
 #include "extmod/vfs.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 
 STATIC int MP_VFS_LFSx(dev_ioctl)(const struct LFSx_API (config) * c, int cmd, int arg, bool must_return_int) {
     mp_obj_t ret = mp_vfs_blockdev_ioctl(c->context, cmd, arg);
diff --git a/lib/README.md b/lib/README.md
index e719821bf..fd7cba910 100644
--- a/lib/README.md
+++ b/lib/README.md
@@ -1,2 +1,3 @@
-This directory contains standard, low-level C libraries with emphasis on
-being independent and efficient.  They can be used by any port.
+This directory contains third-party, low-level C libraries and SDKs.
+Libraries that do not target any specific platform are generally chosen
+based on them being independent and efficient.
diff --git a/lib/axtls b/lib/axtls
index 43a6e6bd3..531cab9c2 160000
--- a/lib/axtls
+++ b/lib/axtls
@@ -1 +1 @@
-Subproject commit 43a6e6bd3bbc03dc501e16b89fba0ef042ed3ea0
+Subproject commit 531cab9c278c947d268bd4c94ecab9153a961b43
diff --git a/extmod/crypto-algorithms/sha256.c b/lib/crypto-algorithms/sha256.c
similarity index 100%
rename from extmod/crypto-algorithms/sha256.c
rename to lib/crypto-algorithms/sha256.c
diff --git a/extmod/crypto-algorithms/sha256.h b/lib/crypto-algorithms/sha256.h
similarity index 100%
rename from extmod/crypto-algorithms/sha256.h
rename to lib/crypto-algorithms/sha256.h
diff --git a/lib/lv_bindings b/lib/lv_bindings
index f6bbc2f06..9c591daaf 160000
--- a/lib/lv_bindings
+++ b/lib/lv_bindings
@@ -1 +1 @@
-Subproject commit f6bbc2f06aaec67c1520c53edfaa97cea4a1c74b
+Subproject commit 9c591daaf40c0ee713588d69973c7c22884d435a
diff --git a/lib/pico-sdk b/lib/pico-sdk
index fc10a97c3..bfcbefafc 160000
--- a/lib/pico-sdk
+++ b/lib/pico-sdk
@@ -1 +1 @@
-Subproject commit fc10a97c386f65c1a44c68684fe52a56aaf50df0
+Subproject commit bfcbefafc5d2a210551a4d9d80b4303d4ae0adf7
diff --git a/extmod/re1.5/charclass.c b/lib/re1.5/charclass.c
similarity index 100%
rename from extmod/re1.5/charclass.c
rename to lib/re1.5/charclass.c
diff --git a/extmod/re1.5/compilecode.c b/lib/re1.5/compilecode.c
similarity index 100%
rename from extmod/re1.5/compilecode.c
rename to lib/re1.5/compilecode.c
diff --git a/extmod/re1.5/dumpcode.c b/lib/re1.5/dumpcode.c
similarity index 100%
rename from extmod/re1.5/dumpcode.c
rename to lib/re1.5/dumpcode.c
diff --git a/extmod/re1.5/re1.5.h b/lib/re1.5/re1.5.h
similarity index 100%
rename from extmod/re1.5/re1.5.h
rename to lib/re1.5/re1.5.h
diff --git a/extmod/re1.5/recursiveloop.c b/lib/re1.5/recursiveloop.c
similarity index 100%
rename from extmod/re1.5/recursiveloop.c
rename to lib/re1.5/recursiveloop.c
diff --git a/lib/tinyusb b/lib/tinyusb
index 7b62c71dd..d49938d0f 160000
--- a/lib/tinyusb
+++ b/lib/tinyusb
@@ -1 +1 @@
-Subproject commit 7b62c71dd5ec42e61499d2d83902df9484842670
+Subproject commit d49938d0f5052bce70e55c652b657c0a6a7e84fe
diff --git a/lib/utils/stdout_helpers.c b/lib/utils/stdout_helpers.c
deleted file mode 100644
index 3de119757..000000000
--- a/lib/utils/stdout_helpers.c
+++ /dev/null
@@ -1,26 +0,0 @@
-#include <string.h>
-#include <unistd.h>
-#include "py/mpconfig.h"
-#include "py/mphal.h"
-
-/*
- * Extra stdout functions
- * These can be either optimized for a particular port, or reference
- * implementation below can be used.
- */
-
-// Send "cooked" string of given length, where every occurrence of
-// LF character is replaced with CR LF.
-void mp_hal_stdout_tx_strn_cooked(const char *str, size_t len) {
-    while (len--) {
-        if (*str == '\n') {
-            mp_hal_stdout_tx_strn("\r", 1);
-        }
-        mp_hal_stdout_tx_strn(str++, 1);
-    }
-}
-
-// Send zero-terminated string
-void mp_hal_stdout_tx_str(const char *str) {
-    mp_hal_stdout_tx_strn(str, strlen(str));
-}
diff --git a/extmod/uzlib/adler32.c b/lib/uzlib/adler32.c
similarity index 100%
rename from extmod/uzlib/adler32.c
rename to lib/uzlib/adler32.c
diff --git a/extmod/uzlib/crc32.c b/lib/uzlib/crc32.c
similarity index 100%
rename from extmod/uzlib/crc32.c
rename to lib/uzlib/crc32.c
diff --git a/extmod/uzlib/defl_static.h b/lib/uzlib/defl_static.h
similarity index 100%
rename from extmod/uzlib/defl_static.h
rename to lib/uzlib/defl_static.h
diff --git a/extmod/uzlib/tinf.h b/lib/uzlib/tinf.h
similarity index 100%
rename from extmod/uzlib/tinf.h
rename to lib/uzlib/tinf.h
diff --git a/extmod/uzlib/tinf_compat.h b/lib/uzlib/tinf_compat.h
similarity index 100%
rename from extmod/uzlib/tinf_compat.h
rename to lib/uzlib/tinf_compat.h
diff --git a/extmod/uzlib/tinfgzip.c b/lib/uzlib/tinfgzip.c
similarity index 100%
rename from extmod/uzlib/tinfgzip.c
rename to lib/uzlib/tinfgzip.c
diff --git a/extmod/uzlib/tinflate.c b/lib/uzlib/tinflate.c
similarity index 100%
rename from extmod/uzlib/tinflate.c
rename to lib/uzlib/tinflate.c
diff --git a/extmod/uzlib/tinfzlib.c b/lib/uzlib/tinfzlib.c
similarity index 100%
rename from extmod/uzlib/tinfzlib.c
rename to lib/uzlib/tinfzlib.c
diff --git a/extmod/uzlib/uzlib.h b/lib/uzlib/uzlib.h
similarity index 100%
rename from extmod/uzlib/uzlib.h
rename to lib/uzlib/uzlib.h
diff --git a/extmod/uzlib/uzlib_conf.h b/lib/uzlib/uzlib_conf.h
similarity index 100%
rename from extmod/uzlib/uzlib_conf.h
rename to lib/uzlib/uzlib_conf.h
diff --git a/mpy-cross/Makefile b/mpy-cross/Makefile
index 971f2f81a..2189dff90 100644
--- a/mpy-cross/Makefile
+++ b/mpy-cross/Makefile
@@ -48,7 +48,7 @@ LDFLAGS = $(LDFLAGS_MOD) $(LDFLAGS_ARCH) -lm $(LDFLAGS_EXTRA)
 SRC_C = \
 	main.c \
 	gccollect.c \
-	lib/utils/gchelper_generic.c \
+	shared/runtime/gchelper_generic.c \
 
 # Add fmode when compiling with mingw gcc
 COMPILER_TARGET := $(shell $(CC) -dumpmachine)
diff --git a/mpy-cross/gccollect.c b/mpy-cross/gccollect.c
index 120f1a225..72d4204c2 100644
--- a/mpy-cross/gccollect.c
+++ b/mpy-cross/gccollect.c
@@ -29,7 +29,7 @@
 #include "py/mpstate.h"
 #include "py/gc.h"
 
-#include "lib/utils/gchelper.h"
+#include "shared/runtime/gchelper.h"
 
 #if MICROPY_ENABLE_GC
 
diff --git a/mpy-cross/mpconfigport.h b/mpy-cross/mpconfigport.h
index 96d372656..e7c8edf13 100644
--- a/mpy-cross/mpconfigport.h
+++ b/mpy-cross/mpconfigport.h
@@ -76,6 +76,7 @@
 #define MICROPY_CPYTHON_COMPAT      (1)
 #define MICROPY_USE_INTERNAL_PRINTF (0)
 
+#define MICROPY_PY_FSTRINGS         (1)
 #define MICROPY_PY_BUILTINS_STR_UNICODE (1)
 
 #if !(defined(MICROPY_GCREGS_SETJMP) || defined(__x86_64__) || defined(__i386__) || defined(__thumb2__) || defined(__thumb__) || defined(__arm__))
diff --git a/mpy-cross/mpy-cross.vcxproj b/mpy-cross/mpy-cross.vcxproj
index 74a366712..e70b29ae1 100644
--- a/mpy-cross/mpy-cross.vcxproj
+++ b/mpy-cross/mpy-cross.vcxproj
@@ -89,7 +89,7 @@
   <Import Project="$(PyMsvcDir)sources.props" />
   <ItemGroup>
     <ClCompile Include="@(PyCoreSource)" />
-    <ClCompile Include="$(PyBaseDir)lib/utils/gchelper_generic.c" >
+    <ClCompile Include="$(PyBaseDir)shared/runtime/gchelper_generic.c" >
       <PreprocessorDefinitions>MICROPY_GCREGS_SETJMP</PreprocessorDefinitions>
     </ClCompile>
     <ClCompile Include="$(PyBaseDir)mpy-cross\gccollect.c"/>
@@ -103,4 +103,4 @@
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/ports/bare-arm/lib.c b/ports/bare-arm/lib.c
index ee7c1d765..6ef450bea 100644
--- a/ports/bare-arm/lib.c
+++ b/ports/bare-arm/lib.c
@@ -54,7 +54,7 @@ void free(void *p) {
 }
 
 // These standard string functions are needed by the runtime, and can be
-// provided either by the system or lib/libc/string0.c.  The implementations
+// provided either by the system or shared/libc/string0.c.  The implementations
 // here are very simple.
 
 int memcmp(const void *s1, const void *s2, size_t n) {
diff --git a/ports/cc3200/application.mk b/ports/cc3200/application.mk
index 2125274ae..25a9925ea 100644
--- a/ports/cc3200/application.mk
+++ b/ports/cc3200/application.mk
@@ -140,14 +140,18 @@ APP_MAIN_SRC_C = \
 APP_LIB_SRC_C = $(addprefix lib/,\
 	oofatfs/ff.c \
 	oofatfs/ffunicode.c \
+	)
+
+APP_SHARED_SRC_C = $(addprefix shared/,\
 	libc/string0.c \
-	mp-readline/readline.c \
+	readline/readline.c \
 	netutils/netutils.c \
 	timeutils/timeutils.c \
-	utils/gchelper_native.c \
-	utils/pyexec.c \
-	utils/interrupt_char.c \
-	utils/sys_stdio_mphal.c \
+	runtime/gchelper_native.c \
+	runtime/pyexec.c \
+	runtime/interrupt_char.c \
+	runtime/stdout_helpers.c \
+	runtime/sys_stdio_mphal.c \
 	)
 
 APP_STM_SRC_C = $(addprefix ports/stm32/,\
@@ -157,12 +161,12 @@ APP_STM_SRC_C = $(addprefix ports/stm32/,\
 
 OBJ = $(PY_O) $(addprefix $(BUILD)/, $(APP_FATFS_SRC_C:.c=.o) $(APP_RTOS_SRC_C:.c=.o) $(APP_FTP_SRC_C:.c=.o) $(APP_HAL_SRC_C:.c=.o) $(APP_MISC_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(APP_MODS_SRC_C:.c=.o) $(APP_CC3100_SRC_C:.c=.o) $(APP_SL_SRC_C:.c=.o) $(APP_TELNET_SRC_C:.c=.o) $(APP_UTIL_SRC_C:.c=.o) $(APP_UTIL_SRC_S:.s=.o))
-OBJ += $(addprefix $(BUILD)/, $(APP_MAIN_SRC_C:.c=.o) $(APP_LIB_SRC_C:.c=.o) $(APP_STM_SRC_C:.c=.o))
-OBJ += $(BUILD)/lib/utils/gchelper_m3.o
+OBJ += $(addprefix $(BUILD)/, $(APP_MAIN_SRC_C:.c=.o) $(APP_SHARED_SRC_C:.c=.o) $(APP_LIB_SRC_C:.c=.o) $(APP_STM_SRC_C:.c=.o))
+OBJ += $(BUILD)/shared/runtime/gchelper_m3.o
 OBJ += $(BUILD)/pins.o
 
 # List of sources for qstr extraction
-SRC_QSTR += $(APP_MODS_SRC_C) $(APP_MISC_SRC_C) $(APP_STM_SRC_C)
+SRC_QSTR += $(APP_MODS_SRC_C) $(APP_MISC_SRC_C) $(APP_STM_SRC_C) $(APP_SHARED_SRC_C)
 # Append any auto-generated sources that are needed by sources listed in
 # SRC_QSTR
 SRC_QSTR_AUTO_DEPS +=
diff --git a/ports/cc3200/bootmgr/bootloader.mk b/ports/cc3200/bootmgr/bootloader.mk
index 44f1b7f42..1dc2f8286 100644
--- a/ports/cc3200/bootmgr/bootloader.mk
+++ b/ports/cc3200/bootmgr/bootloader.mk
@@ -65,14 +65,14 @@ BOOT_PY_SRC_C = $(addprefix py/,\
 	mpprint.c \
 	)
 
-BOOT_LIB_SRC_C = $(addprefix lib/,\
+BOOT_SHARED_SRC_C = $(addprefix shared/,\
+	libc/printf.c \
 	libc/string0.c \
-	utils/printf.c \
 	)
 
 OBJ  = $(addprefix $(BUILD)/, $(BOOT_HAL_SRC_C:.c=.o) $(BOOT_SL_SRC_C:.c=.o) $(BOOT_CC3100_SRC_C:.c=.o) $(BOOT_UTIL_SRC_C:.c=.o) $(BOOT_MISC_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(BOOT_MAIN_SRC_C:.c=.o) $(BOOT_MAIN_SRC_S:.s=.o) $(BOOT_PY_SRC_C:.c=.o))
-OBJ += $(addprefix $(BUILD)/, $(BOOT_LIB_SRC_C:.c=.o))
+OBJ += $(addprefix $(BUILD)/, $(BOOT_SHARED_SRC_C:.c=.o))
 
 # Add the linker script
 LINKER_SCRIPT = bootmgr/bootmgr.lds
diff --git a/ports/cc3200/fatfs_port.c b/ports/cc3200/fatfs_port.c
index 993684d8c..39b350db6 100644
--- a/ports/cc3200/fatfs_port.c
+++ b/ports/cc3200/fatfs_port.c
@@ -27,7 +27,7 @@
 
 #include "py/runtime.h"
 #include "lib/oofatfs/ff.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "mods/pybrtc.h"
 
 #if FF_FS_REENTRANT
diff --git a/ports/cc3200/ftp/ftp.c b/ports/cc3200/ftp/ftp.c
index 37680bc93..d999e810d 100644
--- a/ports/cc3200/ftp/ftp.c
+++ b/ports/cc3200/ftp/ftp.c
@@ -28,7 +28,7 @@
 #include <stdio.h>
 
 #include "py/runtime.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "lib/oofatfs/ff.h"
 #include "extmod/vfs.h"
 #include "extmod/vfs_fat.h"
diff --git a/ports/cc3200/hal/cc3200_hal.c b/ports/cc3200/hal/cc3200_hal.c
index bdb7d33d4..3a35e39e1 100644
--- a/ports/cc3200/hal/cc3200_hal.c
+++ b/ports/cc3200/hal/cc3200_hal.c
@@ -141,10 +141,6 @@ void mp_hal_delay_ms(mp_uint_t delay) {
     }
 }
 
-void mp_hal_stdout_tx_str(const char *str) {
-    mp_hal_stdout_tx_strn(str, strlen(str));
-}
-
 void mp_hal_stdout_tx_strn(const char *str, size_t len) {
     if (MP_STATE_PORT(os_term_dup_obj)) {
         if (mp_obj_is_type(MP_STATE_PORT(os_term_dup_obj)->stream_o, &pyb_uart_type)) {
@@ -158,25 +154,6 @@ void mp_hal_stdout_tx_strn(const char *str, size_t len) {
     telnet_tx_strn(str, len);
 }
 
-void mp_hal_stdout_tx_strn_cooked (const char *str, size_t len) {
-    int32_t nslen = 0;
-    const char *_str = str;
-
-    for (int i = 0; i < len; i++) {
-        if (str[i] == '\n') {
-            mp_hal_stdout_tx_strn(_str, nslen);
-            mp_hal_stdout_tx_strn("\r\n", 2);
-            _str += nslen + 1;
-            nslen = 0;
-        } else {
-            nslen++;
-        }
-    }
-    if (_str < str + len) {
-        mp_hal_stdout_tx_strn(_str, nslen);
-    }
-}
-
 int mp_hal_stdin_rx_chr(void) {
     for ( ;; ) {
         // read telnet first
diff --git a/ports/cc3200/mods/moduos.c b/ports/cc3200/mods/moduos.c
index 53521fe66..8c3dcf696 100644
--- a/ports/cc3200/mods/moduos.c
+++ b/ports/cc3200/mods/moduos.c
@@ -31,7 +31,7 @@
 #include "py/objtuple.h"
 #include "py/objstr.h"
 #include "py/runtime.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "lib/oofatfs/ff.h"
 #include "lib/oofatfs/diskio.h"
 #include "genhdr/mpversion.h"
diff --git a/ports/cc3200/mods/modusocket.c b/ports/cc3200/mods/modusocket.c
index 5dac0a010..51815a31f 100644
--- a/ports/cc3200/mods/modusocket.c
+++ b/ports/cc3200/mods/modusocket.c
@@ -35,7 +35,7 @@
 #include "py/runtime.h"
 #include "py/stream.h"
 #include "py/mphal.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "modnetwork.h"
 #include "modusocket.h"
 
diff --git a/ports/cc3200/mods/modutime.c b/ports/cc3200/mods/modutime.c
index e77065ef4..c5ff6072f 100644
--- a/ports/cc3200/mods/modutime.c
+++ b/ports/cc3200/mods/modutime.c
@@ -33,7 +33,7 @@
 #include "py/obj.h"
 #include "py/smallint.h"
 #include "py/mphal.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "extmod/utime_mphal.h"
 #include "inc/hw_types.h"
 #include "inc/hw_ints.h"
diff --git a/ports/cc3200/mods/modwlan.c b/ports/cc3200/mods/modwlan.c
index 7aa8f0e2c..920079b58 100644
--- a/ports/cc3200/mods/modwlan.c
+++ b/ports/cc3200/mods/modwlan.c
@@ -35,8 +35,8 @@
 #include "py/runtime.h"
 #include "py/stream.h"
 #include "py/mphal.h"
-#include "lib/timeutils/timeutils.h"
-#include "lib/netutils/netutils.h"
+#include "shared/timeutils/timeutils.h"
+#include "shared/netutils/netutils.h"
 #include "modnetwork.h"
 #include "modusocket.h"
 #include "modwlan.h"
diff --git a/ports/cc3200/mods/pybrtc.c b/ports/cc3200/mods/pybrtc.c
index f0704eecd..6c1918831 100644
--- a/ports/cc3200/mods/pybrtc.c
+++ b/ports/cc3200/mods/pybrtc.c
@@ -29,7 +29,7 @@
 #include "py/obj.h"
 #include "py/runtime.h"
 #include "py/mperrno.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "inc/hw_types.h"
 #include "inc/hw_ints.h"
 #include "inc/hw_memmap.h"
diff --git a/ports/cc3200/mods/pybuart.c b/ports/cc3200/mods/pybuart.c
index ac2af7032..b8e8cbb68 100644
--- a/ports/cc3200/mods/pybuart.c
+++ b/ports/cc3200/mods/pybuart.c
@@ -33,7 +33,7 @@
 #include "py/objlist.h"
 #include "py/stream.h"
 #include "py/mphal.h"
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 #include "inc/hw_types.h"
 #include "inc/hw_ints.h"
 #include "inc/hw_memmap.h"
diff --git a/ports/cc3200/mptask.c b/ports/cc3200/mptask.c
index 71b650ff8..b764c4712 100644
--- a/ports/cc3200/mptask.c
+++ b/ports/cc3200/mptask.c
@@ -33,7 +33,7 @@
 #include "py/runtime.h"
 #include "py/gc.h"
 #include "py/mphal.h"
-#include "lib/mp-readline/readline.h"
+#include "shared/readline/readline.h"
 #include "lib/oofatfs/ff.h"
 #include "lib/oofatfs/diskio.h"
 #include "extmod/vfs.h"
@@ -49,8 +49,8 @@
 #include "pybuart.h"
 #include "pybpin.h"
 #include "pybrtc.h"
-#include "lib/utils/pyexec.h"
-#include "lib/utils/gchelper.h"
+#include "shared/runtime/pyexec.h"
+#include "shared/runtime/gchelper.h"
 #include "gccollect.h"
 #include "mperror.h"
 #include "simplelink.h"
diff --git a/ports/cc3200/telnet/telnet.c b/ports/cc3200/telnet/telnet.c
index 9f51d4cd8..c4daac342 100644
--- a/ports/cc3200/telnet/telnet.c
+++ b/ports/cc3200/telnet/telnet.c
@@ -28,7 +28,7 @@
 
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 #include "telnet.h"
 #include "simplelink.h"
 #include "modnetwork.h"
diff --git a/ports/cc3200/util/gccollect.c b/ports/cc3200/util/gccollect.c
index eac0c86b0..0ff179e48 100644
--- a/ports/cc3200/util/gccollect.c
+++ b/ports/cc3200/util/gccollect.c
@@ -30,7 +30,7 @@
 
 #include "py/gc.h"
 #include "py/mpthread.h"
-#include "lib/utils/gchelper.h"
+#include "shared/runtime/gchelper.h"
 #include "gccollect.h"
 
 /******************************************************************************
diff --git a/ports/esp32/Makefile b/ports/esp32/Makefile
index fc1fc9a33..386e8f98b 100644
--- a/ports/esp32/Makefile
+++ b/ports/esp32/Makefile
@@ -34,6 +34,7 @@ endif
 all:
 	idf.py $(IDFPY_FLAGS) build
 	@$(PYTHON) makeimg.py \
+		$(BUILD)/sdkconfig \
 		$(BUILD)/bootloader/bootloader.bin \
 		$(BUILD)/partition_table/partition-table.bin \
     		$(BUILD)/micropython.bin \
diff --git a/ports/esp32/boards/GENERIC_C3/mpconfigboard.cmake b/ports/esp32/boards/GENERIC_C3/mpconfigboard.cmake
new file mode 100644
index 000000000..4f3188423
--- /dev/null
+++ b/ports/esp32/boards/GENERIC_C3/mpconfigboard.cmake
@@ -0,0 +1,10 @@
+set(IDF_TARGET esp32c3)
+
+set(SDKCONFIG_DEFAULTS
+    boards/sdkconfig.base
+    boards/sdkconfig.ble
+)
+
+if(NOT MICROPY_FROZEN_MANIFEST)
+    set(MICROPY_FROZEN_MANIFEST ${MICROPY_PORT_DIR}/boards/manifest.py)
+endif()
diff --git a/ports/esp32/boards/GENERIC_C3/mpconfigboard.h b/ports/esp32/boards/GENERIC_C3/mpconfigboard.h
new file mode 100644
index 000000000..d403e70e4
--- /dev/null
+++ b/ports/esp32/boards/GENERIC_C3/mpconfigboard.h
@@ -0,0 +1,8 @@
+// This configuration is for a generic ESP32C3 board with 4MiB (or more) of flash.
+
+#define MICROPY_HW_BOARD_NAME               "ESP32C3 module"
+#define MICROPY_HW_MCU_NAME                 "ESP32C3"
+
+#define MICROPY_HW_ENABLE_SDCARD            (0)
+#define MICROPY_PY_MACHINE_DAC              (0)
+#define MICROPY_PY_MACHINE_I2S              (0)
diff --git a/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.cmake b/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.cmake
new file mode 100644
index 000000000..2b65121b9
--- /dev/null
+++ b/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.cmake
@@ -0,0 +1,11 @@
+set(IDF_TARGET esp32c3)
+
+set(SDKCONFIG_DEFAULTS
+    boards/sdkconfig.base
+    boards/sdkconfig.ble
+    boards/GENERIC_C3_USB/sdkconfig.board
+)
+
+if(NOT MICROPY_FROZEN_MANIFEST)
+    set(MICROPY_FROZEN_MANIFEST ${MICROPY_PORT_DIR}/boards/manifest.py)
+endif()
diff --git a/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.h b/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.h
new file mode 100644
index 000000000..d403e70e4
--- /dev/null
+++ b/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.h
@@ -0,0 +1,8 @@
+// This configuration is for a generic ESP32C3 board with 4MiB (or more) of flash.
+
+#define MICROPY_HW_BOARD_NAME               "ESP32C3 module"
+#define MICROPY_HW_MCU_NAME                 "ESP32C3"
+
+#define MICROPY_HW_ENABLE_SDCARD            (0)
+#define MICROPY_PY_MACHINE_DAC              (0)
+#define MICROPY_PY_MACHINE_I2S              (0)
diff --git a/ports/esp32/boards/GENERIC_C3_USB/sdkconfig.board b/ports/esp32/boards/GENERIC_C3_USB/sdkconfig.board
new file mode 100644
index 000000000..f0cbad00e
--- /dev/null
+++ b/ports/esp32/boards/GENERIC_C3_USB/sdkconfig.board
@@ -0,0 +1,9 @@
+CONFIG_ESP32C3_REV_MIN_3=y
+CONFIG_ESP32C3_REV_MIN=3
+CONFIG_ESP32C3_BROWNOUT_DET=y
+CONFIG_ESP32C3_BROWNOUT_DET_LVL_SEL_7=
+CONFIG_ESP32C3_BROWNOUT_DET_LVL_SEL_4=y
+CONFIG_ESP32C3_BROWNOUT_DET_LVL=4
+CONFIG_ESP_CONSOLE_UART_DEFAULT=
+CONFIG_ESP_CONSOLE_USB_CDC=
+CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG=y
diff --git a/ports/esp32/boards/SIL_WESP32/mpconfigboard.cmake b/ports/esp32/boards/SIL_WESP32/mpconfigboard.cmake
new file mode 100644
index 000000000..885d4eaa2
--- /dev/null
+++ b/ports/esp32/boards/SIL_WESP32/mpconfigboard.cmake
@@ -0,0 +1,10 @@
+set(SDKCONFIG_DEFAULTS
+    boards/sdkconfig.base
+    boards/sdkconfig.ble
+    boards/sdkconfig.240mhz
+    boards/SIL_WESP32/sdkconfig.board
+)
+
+if(NOT MICROPY_FROZEN_MANIFEST)
+    set(MICROPY_FROZEN_MANIFEST ${MICROPY_PORT_DIR}/boards/manifest.py)
+endif()
diff --git a/ports/esp32/boards/SIL_WESP32/mpconfigboard.h b/ports/esp32/boards/SIL_WESP32/mpconfigboard.h
new file mode 100644
index 000000000..fc66aac64
--- /dev/null
+++ b/ports/esp32/boards/SIL_WESP32/mpconfigboard.h
@@ -0,0 +1,2 @@
+#define MICROPY_HW_BOARD_NAME "Silicognition wESP32"
+#define MICROPY_HW_MCU_NAME "ESP32"
diff --git a/ports/esp32/boards/SIL_WESP32/sdkconfig.board b/ports/esp32/boards/SIL_WESP32/sdkconfig.board
new file mode 100644
index 000000000..98eef1d10
--- /dev/null
+++ b/ports/esp32/boards/SIL_WESP32/sdkconfig.board
@@ -0,0 +1,22 @@
+# 16 MB flash
+
+CONFIG_ESPTOOLPY_FLASHSIZE_4MB=
+CONFIG_ESPTOOLPY_FLASHSIZE_8MB=
+CONFIG_ESPTOOLPY_FLASHSIZE_16MB=y
+CONFIG_ESPTOOLPY_FLASHSIZE="16MB"
+
+# Fast flash
+
+CONFIG_FLASHMODE_QIO=y
+CONFIG_ESPTOOLPY_FLASHFREQ_80M=y
+CONFIG_ESP32_REV_MIN_1=y
+
+# OTA
+
+CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE=y
+CONFIG_PARTITION_TABLE_CUSTOM=y
+CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions-16MiB-ota.csv"
+
+# Network name
+
+CONFIG_LWIP_LOCAL_HOSTNAME="wESP32"
diff --git a/ports/esp32/boards/manifest.py b/ports/esp32/boards/manifest.py
index b463c131f..1dc1481a4 100644
--- a/ports/esp32/boards/manifest.py
+++ b/ports/esp32/boards/manifest.py
@@ -5,3 +5,4 @@ freeze("$(MPY_DIR)/drivers/dht", "dht.py")
 freeze("$(MPY_DIR)/drivers/onewire")
 include("$(MPY_DIR)/extmod/uasyncio/manifest.py")
 include("$(MPY_DIR)/extmod/webrepl/manifest.py")
+include("$(MPY_DIR)/drivers/neopixel/manifest.py")
diff --git a/ports/esp32/espneopixel.c b/ports/esp32/espneopixel.c
deleted file mode 100644
index a5937b9c6..000000000
--- a/ports/esp32/espneopixel.c
+++ /dev/null
@@ -1,71 +0,0 @@
-// Original version from https://github.com/adafruit/Adafruit_NeoPixel
-// Modifications by dpgeorge to support auto-CPU-frequency detection
-
-// This is a mash-up of the Due show() code + insights from Michael Miller's
-// ESP8266 work for the NeoPixelBus library: github.com/Makuna/NeoPixelBus
-// Needs to be a separate .c file to enforce ICACHE_RAM_ATTR execution.
-
-#include "py/mpconfig.h"
-#include "py/mphal.h"
-#include "modesp.h"
-
-void IRAM_ATTR esp_neopixel_write(uint8_t pin, uint8_t *pixels, uint32_t numBytes, uint8_t timing) {
-    uint8_t *p, *end, pix, mask;
-    uint32_t t, time0, time1, period, c, startTime, pinMask, gpio_reg_set, gpio_reg_clear;
-
-    if (pin < 32) {
-        pinMask = 1 << pin;
-        gpio_reg_set = GPIO_OUT_W1TS_REG;
-        gpio_reg_clear = GPIO_OUT_W1TC_REG;
-    } else {
-        pinMask = 1 << (pin - 32);
-        gpio_reg_set = GPIO_OUT1_W1TS_REG;
-        gpio_reg_clear = GPIO_OUT1_W1TC_REG;
-    }
-    p = pixels;
-    end = p + numBytes;
-    pix = *p++;
-    mask = 0x80;
-    startTime = 0;
-
-    uint32_t fcpu = ets_get_cpu_frequency();
-
-    if (timing == 1) {
-        // 800 KHz
-        time0 = (fcpu * 350) / 1000; // 0.35us
-        time1 = (fcpu * 800) / 1000; // 0.8us
-        period = (fcpu * 1250) / 1000; // 1.25us per bit
-    } else {
-        // 400 KHz
-        time0 = (fcpu * 500) / 1000; // 0.5us
-        time1 = (fcpu * 1200) / 1000; // 1.2us
-        period = (fcpu * 2500) / 1000; // 2.5us per bit
-    }
-
-    uint32_t irq_state = mp_hal_quiet_timing_enter();
-    for (t = time0;; t = time0) {
-        if (pix & mask) {
-            t = time1;                                              // Bit high duration
-        }
-        while (((c = mp_hal_ticks_cpu()) - startTime) < period) {
-            ;                                                       // Wait for bit start
-        }
-        GPIO_REG_WRITE(gpio_reg_set, pinMask);                      // Set high
-        startTime = c;                                              // Save start time
-        while (((c = mp_hal_ticks_cpu()) - startTime) < t) {
-            ;                                                       // Wait high duration
-        }
-        GPIO_REG_WRITE(gpio_reg_clear, pinMask);                    // Set low
-        if (!(mask >>= 1)) {                                        // Next bit/byte
-            if (p >= end) {
-                break;
-            }
-            pix = *p++;
-            mask = 0x80;
-        }
-    }
-    while ((mp_hal_ticks_cpu() - startTime) < period) {
-        ;                                              // Wait for last bit
-    }
-    mp_hal_quiet_timing_exit(irq_state);
-}
diff --git a/ports/esp32/fatfs_port.c b/ports/esp32/fatfs_port.c
index 7fce654c0..b9ad30a12 100644
--- a/ports/esp32/fatfs_port.c
+++ b/ports/esp32/fatfs_port.c
@@ -28,7 +28,7 @@
 
 #include <sys/time.h>
 #include "lib/oofatfs/ff.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 
 DWORD get_fattime(void) {
     struct timeval tv;
diff --git a/ports/esp32/gccollect.c b/ports/esp32/gccollect.c
index 7d5da57e7..403a3c7df 100644
--- a/ports/esp32/gccollect.c
+++ b/ports/esp32/gccollect.c
@@ -35,8 +35,10 @@
 #include "py/mpthread.h"
 #include "gccollect.h"
 #include "soc/cpu.h"
-#include "xtensa/hal.h"
 
+#if CONFIG_IDF_TARGET_ESP32 || CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3
+
+#include "xtensa/hal.h"
 
 static void gc_collect_inner(int level) {
     if (level < XCHAL_NUM_AREGS / 8) {
@@ -64,3 +66,18 @@ void gc_collect(void) {
     gc_collect_inner(0);
     gc_collect_end();
 }
+
+#elif CONFIG_IDF_TARGET_ESP32C3
+
+#include "shared/runtime/gchelper.h"
+
+void gc_collect(void) {
+    gc_collect_start();
+    gc_helper_collect_regs_and_stack();
+    #if MICROPY_PY_THREAD
+    mp_thread_gc_others();
+    #endif
+    gc_collect_end();
+}
+
+#endif
diff --git a/ports/esp32/machine_adc.c b/ports/esp32/machine_adc.c
index 739d47da5..5ac05d56b 100644
--- a/ports/esp32/machine_adc.c
+++ b/ports/esp32/machine_adc.c
@@ -52,6 +52,12 @@ STATIC const madc_obj_t madc_obj[] = {
     {{&machine_adc_type}, GPIO_NUM_33, ADC1_CHANNEL_5},
     {{&machine_adc_type}, GPIO_NUM_34, ADC1_CHANNEL_6},
     {{&machine_adc_type}, GPIO_NUM_35, ADC1_CHANNEL_7},
+    #elif CONFIG_IDF_TARGET_ESP32C3
+    {{&machine_adc_type}, GPIO_NUM_0, ADC1_CHANNEL_0},
+    {{&machine_adc_type}, GPIO_NUM_1, ADC1_CHANNEL_1},
+    {{&machine_adc_type}, GPIO_NUM_2, ADC1_CHANNEL_2},
+    {{&machine_adc_type}, GPIO_NUM_3, ADC1_CHANNEL_3},
+    {{&machine_adc_type}, GPIO_NUM_4, ADC1_CHANNEL_4},
     #elif CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3
     {{&machine_adc_type}, GPIO_NUM_1, ADC1_CHANNEL_0},
     {{&machine_adc_type}, GPIO_NUM_2, ADC1_CHANNEL_1},
diff --git a/ports/esp32/machine_bitstream.c b/ports/esp32/machine_bitstream.c
new file mode 100644
index 000000000..9d2bb5724
--- /dev/null
+++ b/ports/esp32/machine_bitstream.c
@@ -0,0 +1,86 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Jim Mussared
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+// This is a translation of the cycle counter implementation in ports/stm32/machine_bitstream.c.
+
+#include "py/mpconfig.h"
+#include "py/mphal.h"
+
+#if MICROPY_PY_MACHINE_BITSTREAM
+
+#define NS_TICKS_OVERHEAD (6)
+
+void IRAM_ATTR machine_bitstream_high_low(mp_hal_pin_obj_t pin, uint32_t *timing_ns, const uint8_t *buf, size_t len) {
+    uint32_t pin_mask, gpio_reg_set, gpio_reg_clear;
+    #if !CONFIG_IDF_TARGET_ESP32C3
+    if (pin >= 32) {
+        pin_mask = 1 << (pin - 32);
+        gpio_reg_set = GPIO_OUT1_W1TS_REG;
+        gpio_reg_clear = GPIO_OUT1_W1TC_REG;
+    } else
+    #endif
+    {
+        pin_mask = 1 << pin;
+        gpio_reg_set = GPIO_OUT_W1TS_REG;
+        gpio_reg_clear = GPIO_OUT_W1TC_REG;
+    }
+
+    // Convert ns to cpu ticks [high_time_0, period_0, high_time_1, period_1].
+    uint32_t fcpu_mhz = ets_get_cpu_frequency();
+    for (size_t i = 0; i < 4; ++i) {
+        timing_ns[i] = fcpu_mhz * timing_ns[i] / 1000;
+        if (timing_ns[i] > NS_TICKS_OVERHEAD) {
+            timing_ns[i] -= NS_TICKS_OVERHEAD;
+        }
+        if (i % 2 == 1) {
+            // Convert low_time to period (i.e. add high_time).
+            timing_ns[i] += timing_ns[i - 1];
+        }
+    }
+
+    uint32_t irq_state = mp_hal_quiet_timing_enter();
+
+    for (size_t i = 0; i < len; ++i) {
+        uint8_t b = buf[i];
+        for (size_t j = 0; j < 8; ++j) {
+            GPIO_REG_WRITE(gpio_reg_set, pin_mask);
+            uint32_t start_ticks = mp_hal_ticks_cpu();
+            uint32_t *t = &timing_ns[b >> 6 & 2];
+            while (mp_hal_ticks_cpu() - start_ticks < t[0]) {
+                ;
+            }
+            GPIO_REG_WRITE(gpio_reg_clear, pin_mask);
+            b <<= 1;
+            while (mp_hal_ticks_cpu() - start_ticks < t[1]) {
+                ;
+            }
+        }
+    }
+
+    mp_hal_quiet_timing_exit(irq_state);
+}
+
+#endif // MICROPY_PY_MACHINE_BITSTREAM
diff --git a/ports/esp32/machine_dac.c b/ports/esp32/machine_dac.c
index 146ef60aa..35826d4a9 100644
--- a/ports/esp32/machine_dac.c
+++ b/ports/esp32/machine_dac.c
@@ -27,15 +27,15 @@
 
 #include <stdio.h>
 
-#include "esp_log.h"
-
-#include "driver/gpio.h"
-#include "driver/dac.h"
-
 #include "py/runtime.h"
 #include "py/mphal.h"
 #include "modmachine.h"
 
+#if MICROPY_PY_MACHINE_DAC
+
+#include "driver/gpio.h"
+#include "driver/dac.h"
+
 typedef struct _mdac_obj_t {
     mp_obj_base_t base;
     gpio_num_t gpio_id;
@@ -111,3 +111,5 @@ const mp_obj_type_t machine_dac_type = {
     .make_new = mdac_make_new,
     .locals_dict = (mp_obj_t)&mdac_locals_dict,
 };
+
+#endif // MICROPY_PY_MACHINE_DAC
diff --git a/ports/esp32/machine_hw_spi.c b/ports/esp32/machine_hw_spi.c
index 98c0abaef..ca530ba94 100644
--- a/ports/esp32/machine_hw_spi.c
+++ b/ports/esp32/machine_hw_spi.c
@@ -53,6 +53,10 @@
 #define MP_HW_SPI_MAX_XFER_BYTES (4092)
 #define MP_HW_SPI_MAX_XFER_BITS (MP_HW_SPI_MAX_XFER_BYTES * 8) // Has to be an even multiple of 8
 
+#if CONFIG_IDF_TARGET_ESP32C3
+#define HSPI_HOST SPI2_HOST
+#endif
+
 typedef struct _machine_hw_spi_default_pins_t {
     int8_t sck;
     int8_t mosi;
@@ -144,9 +148,13 @@ STATIC void machine_hw_spi_init_internal(
         changed = true;
     }
 
-    if (baudrate != -1 && baudrate != self->baudrate) {
-        self->baudrate = baudrate;
-        changed = true;
+    if (baudrate != -1) {
+        // calculate the actual clock frequency that the SPI peripheral can produce
+        baudrate = spi_get_actual_clock(APB_CLK_FREQ, baudrate, 0);
+        if (baudrate != self->baudrate) {
+            self->baudrate = baudrate;
+            changed = true;
+        }
     }
 
     if (polarity != -1 && polarity != self->polarity) {
@@ -213,7 +221,7 @@ STATIC void machine_hw_spi_init_internal(
         .clock_speed_hz = self->baudrate,
         .mode = self->phase | (self->polarity << 1),
         .spics_io_num = -1, // No CS pin
-        .queue_size = 1,
+        .queue_size = 2,
         .flags = self->firstbit == MICROPY_PY_MACHINE_SPI_LSB ? SPI_DEVICE_TXBIT_LSBFIRST | SPI_DEVICE_RXBIT_LSBFIRST : 0,
         .pre_cb = NULL
     };
@@ -269,6 +277,17 @@ STATIC void machine_hw_spi_deinit(mp_obj_base_t *self_in) {
     }
 }
 
+STATIC mp_uint_t gcd(mp_uint_t x, mp_uint_t y) {
+    while (x != y) {
+        if (x > y) {
+            x -= y;
+        } else {
+            y -= x;
+        }
+    }
+    return x;
+}
+
 STATIC void machine_hw_spi_transfer(mp_obj_base_t *self_in, size_t len, const uint8_t *src, uint8_t *dest) {
     machine_hw_spi_obj_t *self = MP_OBJ_TO_PTR(self_in);
 
@@ -277,13 +296,16 @@ STATIC void machine_hw_spi_transfer(mp_obj_base_t *self_in, size_t len, const ui
         return;
     }
 
-    struct spi_transaction_t transaction = { 0 };
-
     // Round to nearest whole set of bits
     int bits_to_send = len * 8 / self->bits * self->bits;
 
+    if (!bits_to_send) {
+        mp_raise_ValueError(MP_ERROR_TEXT("buffer too short"));
+    }
 
     if (len <= 4) {
+        spi_transaction_t transaction = { 0 };
+
         if (src != NULL) {
             memcpy(&transaction.tx_data, src, len);
         }
@@ -298,26 +320,46 @@ STATIC void machine_hw_spi_transfer(mp_obj_base_t *self_in, size_t len, const ui
     } else {
         int offset = 0;
         int bits_remaining = bits_to_send;
+        int optimum_word_size = 8 * self->bits / gcd(8, self->bits);
+        int max_transaction_bits = MP_HW_SPI_MAX_XFER_BITS / optimum_word_size * optimum_word_size;
+        spi_transaction_t *transaction, *result, transactions[2];
+        int i = 0;
+
+        spi_device_acquire_bus(self->spi, portMAX_DELAY);
 
         while (bits_remaining) {
-            memset(&transaction, 0, sizeof(transaction));
+            transaction = transactions + i++ % 2;
+            memset(transaction, 0, sizeof(spi_transaction_t));
 
-            transaction.length =
-                bits_remaining > MP_HW_SPI_MAX_XFER_BITS ? MP_HW_SPI_MAX_XFER_BITS : bits_remaining;
+            transaction->length =
+                bits_remaining > max_transaction_bits ? max_transaction_bits : bits_remaining;
 
             if (src != NULL) {
-                transaction.tx_buffer = src + offset;
+                transaction->tx_buffer = src + offset;
             }
             if (dest != NULL) {
-                transaction.rx_buffer = dest + offset;
+                transaction->rx_buffer = dest + offset;
             }
 
-            spi_device_transmit(self->spi, &transaction);
-            bits_remaining -= transaction.length;
+            spi_device_queue_trans(self->spi, transaction, portMAX_DELAY);
+            bits_remaining -= transaction->length;
+
+            if (offset > 0) {
+                // wait for previously queued transaction
+                MP_THREAD_GIL_EXIT();
+                spi_device_get_trans_result(self->spi, &result, portMAX_DELAY);
+                MP_THREAD_GIL_ENTER();
+            }
 
             // doesn't need ceil(); loop ends when bits_remaining is 0
-            offset += transaction.length / 8;
+            offset += transaction->length / 8;
         }
+
+        // wait for last transaction
+        MP_THREAD_GIL_EXIT();
+        spi_device_get_trans_result(self->spi, &result, portMAX_DELAY);
+        MP_THREAD_GIL_ENTER();
+        spi_device_release_bus(self->spi);
     }
 }
 
diff --git a/ports/esp32/machine_i2s.c b/ports/esp32/machine_i2s.c
new file mode 100644
index 000000000..c650a33be
--- /dev/null
+++ b/ports/esp32/machine_i2s.c
@@ -0,0 +1,813 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Mike Teachman
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include "py/obj.h"
+#include "py/runtime.h"
+#include "py/misc.h"
+#include "py/stream.h"
+#include "py/objstr.h"
+#include "modmachine.h"
+#include "mphalport.h"
+
+#if MICROPY_PY_MACHINE_I2S
+
+#include "driver/i2s.h"
+#include "soc/i2s_reg.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/queue.h"
+#include "esp_task.h"
+
+// The I2S module has 3 modes of operation:
+//
+// Mode1:  Blocking
+// - readinto() and write() methods block until the supplied buffer is filled (read) or emptied (write)
+// - this is the default mode of operation
+//
+// Mode2:  Non-Blocking
+// - readinto() and write() methods return immediately.
+// - buffer filling and emptying happens asynchronously to the main MicroPython task
+// - a callback function is called when the supplied buffer has been filled (read) or emptied (write)
+// - non-blocking mode is enabled when a callback is set with the irq() method
+// - a FreeRTOS task is created to implement the asynchronous background operations
+// - a FreeRTOS queue is used to transfer the supplied buffer to the background task
+//
+// Mode3: Uasyncio
+// - implements the stream protocol
+// - uasyncio mode is enabled when the ioctl() function is called
+// - the I2S event queue is used to detect that I2S samples can be read or written from/to DMA memory
+//
+// The samples contained in the app buffer supplied for the readinto() and write() methods have the following convention:
+//   Mono:  little endian format
+//   Stereo:  little endian format, left channel first
+//
+// I2S terms:
+//   "frame":  consists of two audio samples (Left audio sample + Right audio sample)
+//
+// Misc:
+// - for Mono configuration:
+//   - readinto method: samples are gathered from the L channel only
+//   - write method: every sample is output to both the L and R channels
+// - for readinto method the I2S hardware is read using 8-byte frames
+//   (this is standard for almost all I2S hardware, such as MEMS microphones)
+// - all sample data transfers use DMA
+
+#define I2S_TASK_PRIORITY        (ESP_TASK_PRIO_MIN + 1)
+#define I2S_TASK_STACK_SIZE      (2048)
+
+#define DMA_BUF_LEN_IN_I2S_FRAMES (256)
+
+// The transform buffer is used with the readinto() method to bridge the opaque DMA memory on the ESP devices
+// with the app buffer.  It facilitates audio sample transformations.  e.g.  32-bits samples to 16-bit samples.
+// The size of 240 bytes is an engineering optimum that balances transfer performance with an acceptable use of heap space
+#define SIZEOF_TRANSFORM_BUFFER_IN_BYTES (240)
+
+#define NUM_I2S_USER_FORMATS (4)
+#define I2S_RX_FRAME_SIZE_IN_BYTES (8)
+
+typedef enum {
+    MONO,
+    STEREO
+} format_t;
+
+typedef enum {
+    BLOCKING,
+    NON_BLOCKING,
+    UASYNCIO
+} io_mode_t;
+
+typedef enum {
+    I2S_TX_TRANSFER,
+    I2S_RX_TRANSFER,
+} direction_t;
+
+typedef struct _non_blocking_descriptor_t {
+    mp_buffer_info_t appbuf;
+    mp_obj_t callback;
+    direction_t direction;
+} non_blocking_descriptor_t;
+
+typedef struct _machine_i2s_obj_t {
+    mp_obj_base_t base;
+    i2s_port_t port;
+    mp_hal_pin_obj_t sck;
+    mp_hal_pin_obj_t ws;
+    mp_hal_pin_obj_t sd;
+    int8_t mode;
+    i2s_bits_per_sample_t bits;
+    format_t format;
+    int32_t rate;
+    int32_t ibuf;
+    mp_obj_t callback_for_non_blocking;
+    io_mode_t io_mode;
+    uint8_t transform_buffer[SIZEOF_TRANSFORM_BUFFER_IN_BYTES];
+    QueueHandle_t i2s_event_queue;
+    QueueHandle_t non_blocking_mode_queue;
+    TaskHandle_t non_blocking_mode_task;
+} machine_i2s_obj_t;
+
+STATIC mp_obj_t machine_i2s_deinit(mp_obj_t self_in);
+
+// The frame map is used with the readinto() method to transform the audio sample data coming
+// from DMA memory (32-bit stereo, with the L and R channels reversed) to the format specified
+// in the I2S constructor.  e.g.  16-bit mono
+STATIC const int8_t i2s_frame_map[NUM_I2S_USER_FORMATS][I2S_RX_FRAME_SIZE_IN_BYTES] = {
+    { 6,  7, -1, -1, -1, -1, -1, -1 },  // Mono, 16-bits
+    { 4,  5,  6,  7, -1, -1, -1, -1 },  // Mono, 32-bits
+    { 6,  7,  2,  3, -1, -1, -1, -1 },  // Stereo, 16-bits
+    { 4,  5,  6,  7,  0,  1,  2,  3 },  // Stereo, 32-bits
+};
+
+STATIC machine_i2s_obj_t *machine_i2s_obj[I2S_NUM_MAX];
+
+void machine_i2s_init0() {
+    for (i2s_port_t p = 0; p < I2S_NUM_MAX; p++) {
+        machine_i2s_obj[p] = NULL;
+    }
+}
+
+//  The following function takes a sample buffer and swaps L/R channels
+//
+//  Background:  For 32-bit stereo, the ESP-IDF API has a L/R channel orientation that breaks
+//               convention with other ESP32 channel formats
+//
+//   appbuf[] = [L_0-7, L_8-15, L_16-23, L_24-31, R_0-7, R_8-15, R_16-23, R_24-31] = [Left channel, Right channel]
+//   dma[] =    [R_0-7, R_8-15, R_16-23, R_24-31, L_0-7, L_8-15, L_16-23, L_24-31] = [Right channel, Left channel]
+//
+//   where:
+//     L_0-7 is the least significant byte of the 32 bit sample in the Left channel
+//     L_24-31 is the most significant byte of the 32 bit sample in the Left channel
+//
+//  Example:
+//
+//   appbuf[] = [0x99, 0xBB, 0x11, 0x22, 0x44, 0x55, 0xAB, 0x77] = [Left channel, Right channel]
+//   dma[] =    [0x44, 0x55, 0xAB, 0x77, 0x99, 0xBB, 0x11, 0x22] = [Right channel,  Left channel]
+//   where:
+//      LEFT Channel =  0x99, 0xBB, 0x11, 0x22
+//      RIGHT Channel = 0x44, 0x55, 0xAB, 0x77
+//
+//    samples in appbuf are in little endian format:
+//       0x77 is the most significant byte of the 32-bit sample
+//       0x44 is the least significant byte of the 32-bit sample
+STATIC void swap_32_bit_stereo_channels(mp_buffer_info_t *bufinfo) {
+    int32_t swap_sample;
+    int32_t *sample = bufinfo->buf;
+    uint32_t num_samples = bufinfo->len / 4;
+    for (uint32_t i = 0; i < num_samples; i += 2) {
+        swap_sample = sample[i + 1];
+        sample[i + 1] = sample[i];
+        sample[i] = swap_sample;
+    }
+}
+
+STATIC int8_t get_frame_mapping_index(i2s_bits_per_sample_t bits, format_t format) {
+    if (format == MONO) {
+        if (bits == I2S_BITS_PER_SAMPLE_16BIT) {
+            return 0;
+        } else { // 32 bits
+            return 1;
+        }
+    } else { // STEREO
+        if (bits == I2S_BITS_PER_SAMPLE_16BIT) {
+            return 2;
+        } else { // 32 bits
+            return 3;
+        }
+    }
+}
+
+STATIC i2s_bits_per_sample_t get_dma_bits(uint8_t mode, i2s_bits_per_sample_t bits) {
+    if (mode == (I2S_MODE_MASTER | I2S_MODE_TX)) {
+        return bits;
+    } else { // Master Rx
+        // read 32 bit samples for I2S hardware.  e.g. MEMS microphones
+        return I2S_BITS_PER_SAMPLE_32BIT;
+    }
+}
+
+STATIC i2s_channel_fmt_t get_dma_format(uint8_t mode, format_t format) {
+    if (mode == (I2S_MODE_MASTER | I2S_MODE_TX)) {
+        if (format == MONO) {
+            return I2S_CHANNEL_FMT_ONLY_LEFT;
+        } else {  // STEREO
+            return I2S_CHANNEL_FMT_RIGHT_LEFT;
+        }
+    } else { // Master Rx
+        // read stereo frames for all I2S hardware
+        return I2S_CHANNEL_FMT_RIGHT_LEFT;
+    }
+}
+
+STATIC uint32_t get_dma_buf_count(uint8_t mode, i2s_bits_per_sample_t bits, format_t format, int32_t ibuf) {
+    // calculate how many DMA buffers need to be allocated
+    uint32_t dma_frame_size_in_bytes =
+        (get_dma_bits(mode, bits) / 8) * (get_dma_format(mode, format) == I2S_CHANNEL_FMT_RIGHT_LEFT ? 2: 1);
+
+    uint32_t dma_buf_count = ibuf / (DMA_BUF_LEN_IN_I2S_FRAMES * dma_frame_size_in_bytes);
+
+    return dma_buf_count;
+}
+
+STATIC uint32_t fill_appbuf_from_dma(machine_i2s_obj_t *self, mp_buffer_info_t *appbuf) {
+
+    // copy audio samples from DMA memory to the app buffer
+    // audio samples are read from DMA memory in chunks
+    // loop, reading and copying chunks until the app buffer is filled
+    // For uasyncio mode, the loop will make an early exit if DMA memory becomes empty
+    // Example:
+    //   a MicroPython I2S object is configured for 16-bit mono (2 bytes per audio sample).
+    //   For every frame coming from DMA (8 bytes), 2 bytes are "cherry picked" and
+    //   copied to the supplied app buffer.
+    //   Thus, for every 1 byte copied to the app buffer, 4 bytes are read from DMA memory.
+    //   If a 8kB app buffer is supplied, 32kB of audio samples is read from DMA memory.
+
+    uint32_t a_index = 0;
+    uint8_t *app_p = appbuf->buf;
+    uint8_t appbuf_sample_size_in_bytes = (self->bits / 8) * (self->format == STEREO ? 2: 1);
+    uint32_t num_bytes_needed_from_dma = appbuf->len * (I2S_RX_FRAME_SIZE_IN_BYTES / appbuf_sample_size_in_bytes);
+    while (num_bytes_needed_from_dma) {
+        size_t num_bytes_requested_from_dma = MIN(sizeof(self->transform_buffer), num_bytes_needed_from_dma);
+        size_t num_bytes_received_from_dma = 0;
+
+        TickType_t delay;
+        if (self->io_mode == UASYNCIO) {
+            delay = 0; // stop i2s_read() operation if DMA memory becomes empty
+        } else {
+            delay = portMAX_DELAY;  // block until supplied buffer is filled
+        }
+
+        // read a chunk of audio samples from DMA memory
+        check_esp_err(i2s_read(
+            self->port,
+            self->transform_buffer,
+            num_bytes_requested_from_dma,
+            &num_bytes_received_from_dma,
+            delay));
+
+        // process the transform buffer one frame at a time.
+        // copy selected bytes from the transform buffer into the user supplied appbuf.
+        // Example:
+        //   a MicroPython I2S object is configured for 16-bit mono.  This configuration associates to
+        //   a frame map index of 0 = { 6,  7, -1, -1, -1, -1, -1, -1 } in the i2s_frame_map array
+        //   This mapping indicates:
+        //      appbuf[x+0] = frame[6]
+        //      appbuf[x+1] = frame[7]
+        //      frame bytes 0-5 are not used
+
+        uint32_t t_index = 0;
+        uint8_t f_index = get_frame_mapping_index(self->bits, self->format);
+        while (t_index < num_bytes_received_from_dma) {
+            uint8_t *transform_p = self->transform_buffer + t_index;
+
+            for (uint8_t i = 0; i < I2S_RX_FRAME_SIZE_IN_BYTES; i++) {
+                int8_t t_to_a_mapping = i2s_frame_map[f_index][i];
+                if (t_to_a_mapping != -1) {
+                    *app_p++ = transform_p[t_to_a_mapping];
+                    a_index++;
+                }
+                t_index++;
+            }
+        }
+
+        num_bytes_needed_from_dma -= num_bytes_received_from_dma;
+
+        if ((self->io_mode == UASYNCIO) && (num_bytes_received_from_dma < num_bytes_requested_from_dma)) {
+            // Unable to fill the entire app buffer from DMA memory.  This indicates all DMA RX buffers are empty.
+            // Clear the I2S event queue so ioctl() indicates that the I2S object cannot currently
+            // supply more audio samples
+            xQueueReset(self->i2s_event_queue);
+            break;
+        }
+    }
+
+    return a_index;
+}
+
+STATIC size_t copy_appbuf_to_dma(machine_i2s_obj_t *self, mp_buffer_info_t *appbuf) {
+    if ((self->bits == I2S_BITS_PER_SAMPLE_32BIT) && (self->format == STEREO)) {
+        swap_32_bit_stereo_channels(appbuf);
+    }
+
+    size_t num_bytes_written = 0;
+
+    TickType_t delay;
+    if (self->io_mode == UASYNCIO) {
+        delay = 0;  // stop i2s_write() operation if DMA memory becomes full
+    } else {
+        delay = portMAX_DELAY;  // block until supplied buffer is emptied
+    }
+
+    check_esp_err(i2s_write(self->port, appbuf->buf, appbuf->len, &num_bytes_written, delay));
+
+    if ((self->io_mode == UASYNCIO) && (num_bytes_written < appbuf->len)) {
+        // Unable to empty the entire app buffer into DMA memory.  This indicates all DMA TX buffers are full.
+        // Clear the I2S event queue so ioctl() indicates that the I2S object cannot currently
+        // accept more audio samples
+        xQueueReset(self->i2s_event_queue);
+
+        // Undo the swap transformation as the buffer has not been completely emptied.
+        // The uasyncio stream writer will use the same buffer in a future write call.
+        if ((self->bits == I2S_BITS_PER_SAMPLE_32BIT) && (self->format == STEREO)) {
+            swap_32_bit_stereo_channels(appbuf);
+        }
+    }
+    return num_bytes_written;
+}
+
+// FreeRTOS task used for non-blocking mode
+STATIC void task_for_non_blocking_mode(void *self_in) {
+    machine_i2s_obj_t *self = (machine_i2s_obj_t *)self_in;
+
+    non_blocking_descriptor_t descriptor;
+
+    for (;;) {
+        if (xQueueReceive(self->non_blocking_mode_queue, &descriptor, portMAX_DELAY)) {
+            if (descriptor.direction == I2S_TX_TRANSFER) {
+                copy_appbuf_to_dma(self, &descriptor.appbuf);
+            } else { // RX
+                fill_appbuf_from_dma(self, &descriptor.appbuf);
+            }
+            mp_sched_schedule(descriptor.callback, MP_OBJ_FROM_PTR(self));
+        }
+    }
+}
+
+STATIC void machine_i2s_init_helper(machine_i2s_obj_t *self, size_t n_pos_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+
+    enum {
+        ARG_sck,
+        ARG_ws,
+        ARG_sd,
+        ARG_mode,
+        ARG_bits,
+        ARG_format,
+        ARG_rate,
+        ARG_ibuf,
+    };
+
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_sck,      MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_OBJ,   {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_ws,       MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_OBJ,   {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_sd,       MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_OBJ,   {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_mode,     MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT,   {.u_int = -1} },
+        { MP_QSTR_bits,     MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT,   {.u_int = -1} },
+        { MP_QSTR_format,   MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT,   {.u_int = -1} },
+        { MP_QSTR_rate,     MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT,   {.u_int = -1} },
+        { MP_QSTR_ibuf,     MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT,   {.u_int = -1} },
+    };
+
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_pos_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    //
+    // ---- Check validity of arguments ----
+    //
+
+    // are Pins valid?
+    int8_t sck = args[ARG_sck].u_obj == MP_OBJ_NULL ? -1 : mp_hal_get_pin_obj(args[ARG_sck].u_obj);
+    int8_t ws = args[ARG_ws].u_obj == MP_OBJ_NULL ? -1 : mp_hal_get_pin_obj(args[ARG_ws].u_obj);
+    int8_t sd = args[ARG_sd].u_obj == MP_OBJ_NULL ? -1 : mp_hal_get_pin_obj(args[ARG_sd].u_obj);
+
+    // is Mode valid?
+    i2s_mode_t mode = args[ARG_mode].u_int;
+    if ((mode != (I2S_MODE_MASTER | I2S_MODE_RX)) &&
+        (mode != (I2S_MODE_MASTER | I2S_MODE_TX))) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid mode"));
+    }
+
+    // is Bits valid?
+    i2s_bits_per_sample_t bits = args[ARG_bits].u_int;
+    if ((bits != I2S_BITS_PER_SAMPLE_16BIT) &&
+        (bits != I2S_BITS_PER_SAMPLE_32BIT)) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid bits"));
+    }
+
+    // is Format valid?
+    format_t format = args[ARG_format].u_int;
+    if ((format != STEREO) &&
+        (format != MONO)) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid format"));
+    }
+
+    // is Rate valid?
+    // Not checked:  ESP-IDF I2S API does not indicate a valid range for sample rate
+
+    // is Ibuf valid?
+    // Not checked: ESP-IDF I2S API will return error if requested buffer size exceeds available memory
+
+    self->sck = sck;
+    self->ws = ws;
+    self->sd = sd;
+    self->mode = mode;
+    self->bits = bits;
+    self->format = format;
+    self->rate = args[ARG_rate].u_int;
+    self->ibuf = args[ARG_ibuf].u_int;
+    self->callback_for_non_blocking = MP_OBJ_NULL;
+    self->i2s_event_queue = NULL;
+    self->non_blocking_mode_queue = NULL;
+    self->non_blocking_mode_task = NULL;
+    self->io_mode = BLOCKING;
+
+    i2s_config_t i2s_config;
+    i2s_config.communication_format = I2S_COMM_FORMAT_I2S;
+    i2s_config.mode = mode;
+    i2s_config.bits_per_sample = get_dma_bits(mode, bits);
+    i2s_config.channel_format = get_dma_format(mode, format);
+    i2s_config.sample_rate = self->rate;
+    i2s_config.intr_alloc_flags = ESP_INTR_FLAG_LOWMED;
+    i2s_config.dma_buf_count = get_dma_buf_count(mode, bits, format, self->ibuf);
+    i2s_config.dma_buf_len = DMA_BUF_LEN_IN_I2S_FRAMES;
+    i2s_config.use_apll = false;
+
+    // I2S queue size equals the number of DMA buffers
+    check_esp_err(i2s_driver_install(self->port, &i2s_config, i2s_config.dma_buf_count, &self->i2s_event_queue));
+
+    // apply low-level workaround for bug in some ESP-IDF versions that swap
+    // the left and right channels
+    // https://github.com/espressif/esp-idf/issues/6625
+    REG_SET_BIT(I2S_CONF_REG(self->port), I2S_TX_MSB_RIGHT);
+    REG_SET_BIT(I2S_CONF_REG(self->port), I2S_RX_MSB_RIGHT);
+
+    i2s_pin_config_t pin_config;
+    pin_config.bck_io_num = self->sck;
+    pin_config.ws_io_num = self->ws;
+
+    if (mode == (I2S_MODE_MASTER | I2S_MODE_RX)) {
+        pin_config.data_in_num = self->sd;
+        pin_config.data_out_num = -1;
+    } else { // TX
+        pin_config.data_in_num = -1;
+        pin_config.data_out_num = self->sd;
+    }
+
+    check_esp_err(i2s_set_pin(self->port, &pin_config));
+}
+
+STATIC void machine_i2s_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_printf(print, "I2S(id=%u,\n"
+        "sck="MP_HAL_PIN_FMT ",\n"
+        "ws="MP_HAL_PIN_FMT ",\n"
+        "sd="MP_HAL_PIN_FMT ",\n"
+        "mode=%u,\n"
+        "bits=%u, format=%u,\n"
+        "rate=%d, ibuf=%d)",
+        self->port,
+        mp_hal_pin_name(self->sck),
+        mp_hal_pin_name(self->ws),
+        mp_hal_pin_name(self->sd),
+        self->mode,
+        self->bits, self->format,
+        self->rate, self->ibuf
+        );
+}
+
+STATIC mp_obj_t machine_i2s_make_new(const mp_obj_type_t *type, size_t n_pos_args, size_t n_kw_args, const mp_obj_t *args) {
+    mp_arg_check_num(n_pos_args, n_kw_args, 1, MP_OBJ_FUN_ARGS_MAX, true);
+
+    i2s_port_t port = mp_obj_get_int(args[0]);
+    if (port < 0 || port >= I2S_NUM_MAX) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid id"));
+    }
+
+    machine_i2s_obj_t *self;
+    if (machine_i2s_obj[port] == NULL) {
+        self = m_new_obj(machine_i2s_obj_t);
+        machine_i2s_obj[port] = self;
+        self->base.type = &machine_i2s_type;
+        self->port = port;
+    } else {
+        self = machine_i2s_obj[port];
+        machine_i2s_deinit(self);
+    }
+
+    mp_map_t kw_args;
+    mp_map_init_fixed_table(&kw_args, n_kw_args, args + n_pos_args);
+    machine_i2s_init_helper(self, n_pos_args - 1, args + 1, &kw_args);
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC mp_obj_t machine_i2s_obj_init(size_t n_pos_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    machine_i2s_obj_t *self = pos_args[0];
+    machine_i2s_deinit(self);
+    machine_i2s_init_helper(self, n_pos_args - 1, pos_args + 1, kw_args);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(machine_i2s_init_obj, 1, machine_i2s_obj_init);
+
+STATIC mp_obj_t machine_i2s_deinit(mp_obj_t self_in) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    i2s_driver_uninstall(self->port);
+
+    if (self->non_blocking_mode_task != NULL) {
+        vTaskDelete(self->non_blocking_mode_task);
+        self->non_blocking_mode_task = NULL;
+    }
+
+    if (self->non_blocking_mode_queue != NULL) {
+        vQueueDelete(self->non_blocking_mode_queue);
+        self->non_blocking_mode_queue = NULL;
+    }
+
+    self->i2s_event_queue = NULL;
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_i2s_deinit_obj, machine_i2s_deinit);
+
+STATIC mp_obj_t machine_i2s_irq(mp_obj_t self_in, mp_obj_t handler) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    if (handler != mp_const_none && !mp_obj_is_callable(handler)) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid callback"));
+    }
+
+    if (handler != mp_const_none) {
+        self->io_mode = NON_BLOCKING;
+
+        // create a queue linking the MicroPython task to a FreeRTOS task
+        // that manages the non blocking mode of operation
+        self->non_blocking_mode_queue = xQueueCreate(1, sizeof(non_blocking_descriptor_t));
+
+        // non-blocking mode requires a background FreeRTOS task
+        if (xTaskCreatePinnedToCore(
+            task_for_non_blocking_mode,
+            "i2s_non_blocking",
+            I2S_TASK_STACK_SIZE,
+            self,
+            I2S_TASK_PRIORITY,
+            (TaskHandle_t *)&self->non_blocking_mode_task,
+            MP_TASK_COREID) != pdPASS) {
+
+            mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("failed to create I2S task"));
+        }
+    } else {
+        if (self->non_blocking_mode_task != NULL) {
+            vTaskDelete(self->non_blocking_mode_task);
+            self->non_blocking_mode_task = NULL;
+        }
+
+        if (self->non_blocking_mode_queue != NULL) {
+            vQueueDelete(self->non_blocking_mode_queue);
+            self->non_blocking_mode_queue = NULL;
+        }
+
+        self->io_mode = BLOCKING;
+    }
+
+    self->callback_for_non_blocking = handler;
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(machine_i2s_irq_obj, machine_i2s_irq);
+
+// Shift() is typically used as a volume control.
+// shift=1 increases volume by 6dB, shift=-1 decreases volume by 6dB
+STATIC mp_obj_t machine_i2s_shift(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_buf, ARG_bits, ARG_shift};
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_buf,    MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
+        { MP_QSTR_bits,   MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_shift,  MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+    };
+
+    // parse args
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(args[ARG_buf].u_obj, &bufinfo, MP_BUFFER_RW);
+
+    int16_t *buf_16 = bufinfo.buf;
+    int32_t *buf_32 = bufinfo.buf;
+
+    uint8_t bits = args[ARG_bits].u_int;
+    int8_t shift = args[ARG_shift].u_int;
+
+    uint32_t num_audio_samples;
+    switch (bits) {
+        case 16:
+            num_audio_samples = bufinfo.len / 2;
+            break;
+
+        case 32:
+            num_audio_samples = bufinfo.len / 4;
+            break;
+
+        default:
+            mp_raise_ValueError(MP_ERROR_TEXT("invalid bits"));
+            break;
+    }
+
+    for (uint32_t i = 0; i < num_audio_samples; i++) {
+        switch (bits) {
+            case 16:
+                if (shift >= 0) {
+                    buf_16[i] = buf_16[i] << shift;
+                } else {
+                    buf_16[i] = buf_16[i] >> abs(shift);
+                }
+                break;
+            case 32:
+                if (shift >= 0) {
+                    buf_32[i] = buf_32[i] << shift;
+                } else {
+                    buf_32[i] = buf_32[i] >> abs(shift);
+                }
+                break;
+        }
+    }
+
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(machine_i2s_shift_fun_obj, 0, machine_i2s_shift);
+STATIC MP_DEFINE_CONST_STATICMETHOD_OBJ(machine_i2s_shift_obj, MP_ROM_PTR(&machine_i2s_shift_fun_obj));
+
+STATIC const mp_rom_map_elem_t machine_i2s_locals_dict_table[] = {
+    // Methods
+    { MP_ROM_QSTR(MP_QSTR_init),            MP_ROM_PTR(&machine_i2s_init_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readinto),        MP_ROM_PTR(&mp_stream_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_write),           MP_ROM_PTR(&mp_stream_write_obj) },
+    { MP_ROM_QSTR(MP_QSTR_deinit),          MP_ROM_PTR(&machine_i2s_deinit_obj) },
+    { MP_ROM_QSTR(MP_QSTR_irq),             MP_ROM_PTR(&machine_i2s_irq_obj) },
+
+    // Static method
+    { MP_ROM_QSTR(MP_QSTR_shift),           MP_ROM_PTR(&machine_i2s_shift_obj) },
+
+    // Constants
+    { MP_ROM_QSTR(MP_QSTR_RX),              MP_ROM_INT(I2S_MODE_MASTER | I2S_MODE_RX) },
+    { MP_ROM_QSTR(MP_QSTR_TX),              MP_ROM_INT(I2S_MODE_MASTER | I2S_MODE_TX) },
+    { MP_ROM_QSTR(MP_QSTR_STEREO),          MP_ROM_INT(STEREO) },
+    { MP_ROM_QSTR(MP_QSTR_MONO),            MP_ROM_INT(MONO) },
+};
+MP_DEFINE_CONST_DICT(machine_i2s_locals_dict, machine_i2s_locals_dict_table);
+
+STATIC mp_uint_t machine_i2s_stream_read(mp_obj_t self_in, void *buf_in, mp_uint_t size, int *errcode) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+
+    if (self->mode != (I2S_MODE_MASTER | I2S_MODE_RX)) {
+        *errcode = MP_EPERM;
+        return MP_STREAM_ERROR;
+    }
+
+    uint8_t appbuf_sample_size_in_bytes = (self->bits / 8) * (self->format == STEREO ? 2: 1);
+    if (size % appbuf_sample_size_in_bytes != 0) {
+        *errcode = MP_EINVAL;
+        return MP_STREAM_ERROR;
+    }
+
+    if (size == 0) {
+        return 0;
+    }
+
+    if (self->io_mode == NON_BLOCKING) {
+        non_blocking_descriptor_t descriptor;
+        descriptor.appbuf.buf = (void *)buf_in;
+        descriptor.appbuf.len = size;
+        descriptor.callback = self->callback_for_non_blocking;
+        descriptor.direction = I2S_RX_TRANSFER;
+        // send the descriptor to the task that handles non-blocking mode
+        xQueueSend(self->non_blocking_mode_queue, &descriptor, 0);
+        return size;
+    } else { // blocking or uasyncio mode
+        mp_buffer_info_t appbuf;
+        appbuf.buf = (void *)buf_in;
+        appbuf.len = size;
+        uint32_t num_bytes_read = fill_appbuf_from_dma(self, &appbuf);
+        return num_bytes_read;
+    }
+}
+
+STATIC mp_uint_t machine_i2s_stream_write(mp_obj_t self_in, const void *buf_in, mp_uint_t size, int *errcode) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+
+    if (self->mode != (I2S_MODE_MASTER | I2S_MODE_TX)) {
+        *errcode = MP_EPERM;
+        return MP_STREAM_ERROR;
+    }
+
+    if (size == 0) {
+        return 0;
+    }
+
+    if (self->io_mode == NON_BLOCKING) {
+        non_blocking_descriptor_t descriptor;
+        descriptor.appbuf.buf = (void *)buf_in;
+        descriptor.appbuf.len = size;
+        descriptor.callback = self->callback_for_non_blocking;
+        descriptor.direction = I2S_TX_TRANSFER;
+        // send the descriptor to the task that handles non-blocking mode
+        xQueueSend(self->non_blocking_mode_queue, &descriptor, 0);
+        return size;
+    } else { // blocking or uasyncio mode
+        mp_buffer_info_t appbuf;
+        appbuf.buf = (void *)buf_in;
+        appbuf.len = size;
+        size_t num_bytes_written = copy_appbuf_to_dma(self, &appbuf);
+        return num_bytes_written;
+    }
+}
+
+STATIC mp_uint_t machine_i2s_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_t arg, int *errcode) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_uint_t ret;
+    mp_uint_t flags = arg;
+    self->io_mode = UASYNCIO; // a call to ioctl() is an indication that uasyncio is being used
+
+    if (request == MP_STREAM_POLL) {
+        ret = 0;
+
+        if (flags & MP_STREAM_POLL_RD) {
+            if (self->mode != (I2S_MODE_MASTER | I2S_MODE_RX)) {
+                *errcode = MP_EPERM;
+                return MP_STREAM_ERROR;
+            }
+
+            i2s_event_t i2s_event;
+
+            // check event queue to determine if a DMA buffer has been filled
+            // (which is an indication that at least one DMA buffer is available to be read)
+            // note:  timeout = 0 so the call is non-blocking
+            if (xQueueReceive(self->i2s_event_queue, &i2s_event, 0)) {
+                if (i2s_event.type == I2S_EVENT_RX_DONE) {
+                    // getting here means that at least one DMA buffer is now full
+                    // indicating that audio samples can be read from the I2S object
+                    ret |= MP_STREAM_POLL_RD;
+                }
+            }
+        }
+
+        if (flags & MP_STREAM_POLL_WR) {
+            if (self->mode != (I2S_MODE_MASTER | I2S_MODE_TX)) {
+                *errcode = MP_EPERM;
+                return MP_STREAM_ERROR;
+            }
+
+            i2s_event_t i2s_event;
+
+            // check event queue to determine if a DMA buffer has been emptied
+            // (which is an indication that at least one DMA buffer is available to be written)
+            // note:  timeout = 0 so the call is non-blocking
+            if (xQueueReceive(self->i2s_event_queue, &i2s_event, 0)) {
+                if (i2s_event.type == I2S_EVENT_TX_DONE) {
+                    // getting here means that at least one DMA buffer is now empty
+                    // indicating that audio samples can be written to the I2S object
+                    ret |= MP_STREAM_POLL_WR;
+                }
+            }
+        }
+    } else {
+        *errcode = MP_EINVAL;
+        ret = MP_STREAM_ERROR;
+    }
+
+    return ret;
+}
+
+STATIC const mp_stream_p_t i2s_stream_p = {
+    .read = machine_i2s_stream_read,
+    .write = machine_i2s_stream_write,
+    .ioctl = machine_i2s_ioctl,
+    .is_text = false,
+};
+
+const mp_obj_type_t machine_i2s_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_I2S,
+    .print = machine_i2s_print,
+    .getiter = mp_identity_getiter,
+    .iternext = mp_stream_unbuffered_iter,
+    .protocol = &i2s_stream_p,
+    .make_new = machine_i2s_make_new,
+    .locals_dict = (mp_obj_dict_t *)&machine_i2s_locals_dict,
+};
+
+#endif // MICROPY_PY_MACHINE_I2S
diff --git a/ports/esp32/machine_pin.c b/ports/esp32/machine_pin.c
index bd623d041..6c1e96879 100644
--- a/ports/esp32/machine_pin.c
+++ b/ports/esp32/machine_pin.c
@@ -40,11 +40,21 @@
 #include "machine_rtc.h"
 #include "modesp32.h"
 
+#if CONFIG_IDF_TARGET_ESP32C3
+#include "hal/gpio_ll.h"
+#endif
+
 // Used to implement a range of pull capabilities
 #define GPIO_PULL_DOWN (1)
 #define GPIO_PULL_UP   (2)
 #define GPIO_PULL_HOLD (4)
 
+#if CONFIG_IDF_TARGET_ESP32
+#define GPIO_FIRST_NON_OUTPUT (34)
+#elif CONFIG_IDF_TARGET_ESP32S2
+#define GPIO_FIRST_NON_OUTPUT (46)
+#endif
+
 typedef struct _machine_pin_obj_t {
     mp_obj_base_t base;
     gpio_num_t id;
@@ -99,6 +109,36 @@ STATIC const machine_pin_obj_t machine_pin_obj[] = {
     {{&machine_pin_type}, GPIO_NUM_38},
     {{&machine_pin_type}, GPIO_NUM_39},
 
+    #elif CONFIG_IDF_TARGET_ESP32C3
+
+    {{&machine_pin_type}, GPIO_NUM_0},
+    {{&machine_pin_type}, GPIO_NUM_1},
+    {{&machine_pin_type}, GPIO_NUM_2},
+    {{&machine_pin_type}, GPIO_NUM_3},
+    {{&machine_pin_type}, GPIO_NUM_4},
+    {{&machine_pin_type}, GPIO_NUM_5},
+    {{&machine_pin_type}, GPIO_NUM_6},
+    {{&machine_pin_type}, GPIO_NUM_7},
+    {{&machine_pin_type}, GPIO_NUM_8},
+    {{&machine_pin_type}, GPIO_NUM_9},
+    {{&machine_pin_type}, GPIO_NUM_10},
+    {{&machine_pin_type}, GPIO_NUM_11},
+    {{&machine_pin_type}, GPIO_NUM_12},
+    {{&machine_pin_type}, GPIO_NUM_13},
+    {{NULL}, -1}, // 14 FLASH
+    {{NULL}, -1}, // 15 FLASH
+    {{NULL}, -1}, // 16 FLASH
+    {{NULL}, -1}, // 17 FLASH
+    #if CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
+    {{NULL}, -1}, // 18 is for native USB D-
+    {{NULL}, -1}, // 19 is for native USB D+
+    #else
+    {{&machine_pin_type}, GPIO_NUM_18},
+    {{&machine_pin_type}, GPIO_NUM_19},
+    #endif
+    {{&machine_pin_type}, GPIO_NUM_20},
+    {{&machine_pin_type}, GPIO_NUM_21},
+
     #elif CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3
 
     {{&machine_pin_type}, GPIO_NUM_0},
@@ -213,10 +253,18 @@ STATIC mp_obj_t machine_pin_obj_init_helper(const machine_pin_obj_t *self, size_
     // reset the pin to digital if this is a mode-setting init (grab it back from ADC)
     if (args[ARG_mode].u_obj != mp_const_none) {
         if (rtc_gpio_is_valid_gpio(self->id)) {
+            #if !CONFIG_IDF_TARGET_ESP32C3
             rtc_gpio_deinit(self->id);
+            #endif
         }
     }
 
+    #if CONFIG_IDF_TARGET_ESP32C3
+    if (self->id == 18 || self->id == 19) {
+        CLEAR_PERI_REG_MASK(USB_DEVICE_CONF0_REG, USB_DEVICE_USB_PAD_ENABLE);
+    }
+    #endif
+
     // configure the pin for gpio
     gpio_pad_select_gpio(self->id);
 
@@ -228,11 +276,12 @@ STATIC mp_obj_t machine_pin_obj_init_helper(const machine_pin_obj_t *self, size_
     // configure mode
     if (args[ARG_mode].u_obj != mp_const_none) {
         mp_int_t pin_io_mode = mp_obj_get_int(args[ARG_mode].u_obj);
-        if (self->id >= 34 && (pin_io_mode & GPIO_MODE_DEF_OUTPUT)) {
+        #ifdef GPIO_FIRST_NON_OUTPUT
+        if (self->id >= GPIO_FIRST_NON_OUTPUT && (pin_io_mode & GPIO_MODE_DEF_OUTPUT)) {
             mp_raise_ValueError(MP_ERROR_TEXT("pin can only be input"));
-        } else {
-            gpio_set_direction(self->id, pin_io_mode);
         }
+        #endif
+        gpio_set_direction(self->id, pin_io_mode);
     }
 
     // configure pull
@@ -494,6 +543,31 @@ STATIC const machine_pin_irq_obj_t machine_pin_irq_object[] = {
     {{&machine_pin_irq_type}, GPIO_NUM_38},
     {{&machine_pin_irq_type}, GPIO_NUM_39},
 
+    #elif CONFIG_IDF_TARGET_ESP32C3
+
+    {{&machine_pin_irq_type}, GPIO_NUM_0},
+    {{&machine_pin_irq_type}, GPIO_NUM_1},
+    {{&machine_pin_irq_type}, GPIO_NUM_2},
+    {{&machine_pin_irq_type}, GPIO_NUM_3},
+    {{&machine_pin_irq_type}, GPIO_NUM_4},
+    {{&machine_pin_irq_type}, GPIO_NUM_5},
+    {{&machine_pin_irq_type}, GPIO_NUM_6},
+    {{&machine_pin_irq_type}, GPIO_NUM_7},
+    {{&machine_pin_irq_type}, GPIO_NUM_8},
+    {{&machine_pin_irq_type}, GPIO_NUM_9},
+    {{&machine_pin_irq_type}, GPIO_NUM_10},
+    {{&machine_pin_irq_type}, GPIO_NUM_11},
+    {{&machine_pin_irq_type}, GPIO_NUM_12},
+    {{&machine_pin_irq_type}, GPIO_NUM_13},
+    {{&machine_pin_irq_type}, GPIO_NUM_14},
+    {{&machine_pin_irq_type}, GPIO_NUM_15},
+    {{&machine_pin_irq_type}, GPIO_NUM_16},
+    {{&machine_pin_irq_type}, GPIO_NUM_17},
+    {{&machine_pin_irq_type}, GPIO_NUM_18},
+    {{&machine_pin_irq_type}, GPIO_NUM_19},
+    {{&machine_pin_irq_type}, GPIO_NUM_20},
+    {{&machine_pin_irq_type}, GPIO_NUM_21},
+
     #elif CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3
 
     {{&machine_pin_irq_type}, GPIO_NUM_0},
diff --git a/ports/esp32/machine_rtc.c b/ports/esp32/machine_rtc.c
index 1b6a71b5b..72d7b5c82 100644
--- a/ports/esp32/machine_rtc.c
+++ b/ports/esp32/machine_rtc.c
@@ -36,7 +36,7 @@
 #include "py/obj.h"
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "modmachine.h"
 #include "machine_rtc.h"
 
@@ -121,7 +121,7 @@ STATIC mp_obj_t machine_rtc_datetime_helper(mp_uint_t n_args, const mp_obj_t *ar
         return mp_const_none;
     }
 }
-STATIC mp_obj_t machine_rtc_datetime(mp_uint_t n_args, const mp_obj_t *args) {
+STATIC mp_obj_t machine_rtc_datetime(size_t n_args, const mp_obj_t *args) {
     return machine_rtc_datetime_helper(n_args, args);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(machine_rtc_datetime_obj, 1, 2, machine_rtc_datetime);
@@ -142,7 +142,7 @@ STATIC mp_obj_t machine_rtc_init(mp_obj_t self_in, mp_obj_t date) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(machine_rtc_init_obj, machine_rtc_init);
 
 #if MICROPY_HW_RTC_USER_MEM_MAX > 0
-STATIC mp_obj_t machine_rtc_memory(mp_uint_t n_args, const mp_obj_t *args) {
+STATIC mp_obj_t machine_rtc_memory(size_t n_args, const mp_obj_t *args) {
     if (n_args == 1) {
         // read RTC memory
         uint8_t rtcram[MICROPY_HW_RTC_USER_MEM_MAX];
diff --git a/ports/esp32/machine_timer.c b/ports/esp32/machine_timer.c
index 696127af7..3b1458149 100644
--- a/ports/esp32/machine_timer.c
+++ b/ports/esp32/machine_timer.c
@@ -229,7 +229,7 @@ STATIC mp_obj_t machine_timer_deinit(mp_obj_t self_in) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_timer_deinit_obj, machine_timer_deinit);
 
-STATIC mp_obj_t machine_timer_init(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
+STATIC mp_obj_t machine_timer_init(size_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     return machine_timer_init_helper(args[0], n_args - 1, args + 1, kw_args);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(machine_timer_init_obj, 1, machine_timer_init);
diff --git a/ports/esp32/machine_uart.c b/ports/esp32/machine_uart.c
index e256b9be4..3c90a7215 100644
--- a/ports/esp32/machine_uart.c
+++ b/ports/esp32/machine_uart.c
@@ -53,6 +53,7 @@
 typedef struct _machine_uart_obj_t {
     mp_obj_base_t base;
     uart_port_t uart_num;
+    uart_hw_flowcontrol_t flowcontrol;
     uint8_t bits;
     uint8_t parity;
     uint8_t stop;
@@ -107,11 +108,25 @@ STATIC void machine_uart_print(const mp_print_t *print, mp_obj_t self_in, mp_pri
             mp_printf(print, "INV_CTS");
         }
     }
+    if (self->flowcontrol) {
+        mp_printf(print, ", flow=");
+        uint32_t flow_mask = self->flowcontrol;
+        if (flow_mask & UART_HW_FLOWCTRL_RTS) {
+            mp_printf(print, "RTS");
+            flow_mask &= ~UART_HW_FLOWCTRL_RTS;
+            if (flow_mask) {
+                mp_printf(print, "|");
+            }
+        }
+        if (flow_mask & UART_HW_FLOWCTRL_CTS) {
+            mp_printf(print, "CTS");
+        }
+    }
     mp_printf(print, ")");
 }
 
 STATIC void machine_uart_init_helper(machine_uart_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
-    enum { ARG_baudrate, ARG_bits, ARG_parity, ARG_stop, ARG_tx, ARG_rx, ARG_rts, ARG_cts, ARG_txbuf, ARG_rxbuf, ARG_timeout, ARG_timeout_char, ARG_invert };
+    enum { ARG_baudrate, ARG_bits, ARG_parity, ARG_stop, ARG_tx, ARG_rx, ARG_rts, ARG_cts, ARG_txbuf, ARG_rxbuf, ARG_timeout, ARG_timeout_char, ARG_invert, ARG_flow };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = 0} },
         { MP_QSTR_bits, MP_ARG_INT, {.u_int = 0} },
@@ -126,6 +141,7 @@ STATIC void machine_uart_init_helper(machine_uart_obj_t *self, size_t n_args, co
         { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
         { MP_QSTR_timeout_char, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
         { MP_QSTR_invert, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
+        { MP_QSTR_flow, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
     };
     mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
@@ -257,6 +273,13 @@ STATIC void machine_uart_init_helper(machine_uart_obj_t *self, size_t n_args, co
     }
     self->invert = args[ARG_invert].u_int;
     uart_set_line_inverse(self->uart_num, self->invert);
+
+    // set hardware flow control
+    if (args[ARG_flow].u_int & ~UART_HW_FLOWCTRL_CTS_RTS) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid flow control mask"));
+    }
+    self->flowcontrol = args[ARG_flow].u_int;
+    uart_set_hw_flow_ctrl(self->uart_num, self->flowcontrol, UART_FIFO_LEN - UART_FIFO_LEN / 4);
 }
 
 STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
@@ -400,6 +423,9 @@ STATIC const mp_rom_map_elem_t machine_uart_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_INV_RX), MP_ROM_INT(UART_INV_RX) },
     { MP_ROM_QSTR(MP_QSTR_INV_RTS), MP_ROM_INT(UART_INV_RTS) },
     { MP_ROM_QSTR(MP_QSTR_INV_CTS), MP_ROM_INT(UART_INV_CTS) },
+
+    { MP_ROM_QSTR(MP_QSTR_RTS), MP_ROM_INT(UART_HW_FLOWCTRL_RTS) },
+    { MP_ROM_QSTR(MP_QSTR_CTS), MP_ROM_INT(UART_HW_FLOWCTRL_CTS) },
 };
 
 STATIC MP_DEFINE_CONST_DICT(machine_uart_locals_dict, machine_uart_locals_dict_table);
@@ -443,7 +469,7 @@ STATIC mp_uint_t machine_uart_write(mp_obj_t self_in, const void *buf_in, mp_uin
     return bytes_written;
 }
 
-STATIC mp_uint_t machine_uart_ioctl(mp_obj_t self_in, mp_uint_t request, mp_uint_t arg, int *errcode) {
+STATIC mp_uint_t machine_uart_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_t arg, int *errcode) {
     machine_uart_obj_t *self = self_in;
     mp_uint_t ret;
     if (request == MP_STREAM_POLL) {
diff --git a/ports/esp32/main.c b/ports/esp32/main.c
index bc7b52630..a8ea8f1b5 100644
--- a/ports/esp32/main.c
+++ b/ports/esp32/main.c
@@ -54,10 +54,11 @@
 #include "py/repl.h"
 #include "py/gc.h"
 #include "py/mphal.h"
-#include "lib/mp-readline/readline.h"
-#include "lib/utils/pyexec.h"
+#include "shared/readline/readline.h"
+#include "shared/runtime/pyexec.h"
 #include "uart.h"
 #include "usb.h"
+#include "usb_serial_jtag.h"
 #include "modmachine.h"
 #include "modnetwork.h"
 #include "mpthreadport.h"
@@ -70,6 +71,13 @@
 #define MP_TASK_PRIORITY        (ESP_TASK_PRIO_MIN + 1)
 #define MP_TASK_STACK_SIZE      (32 * 1024)
 
+// Set the margin for detecting stack overflow, depending on the CPU architecture.
+#if CONFIG_IDF_TARGET_ESP32C3
+#define MP_TASK_STACK_LIMIT_MARGIN (2048)
+#else
+#define MP_TASK_STACK_LIMIT_MARGIN (1024)
+#endif
+
 int vprintf_null(const char *format, va_list ap) {
     // do nothing: this is used as a log target during raw repl mode
     return 0;
@@ -82,6 +90,8 @@ void mp_task(void *pvParameter) {
     #endif
     #if CONFIG_USB_ENABLED
     usb_init();
+    #elif CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
+    usb_serial_jtag_init();
     #else
     uart_init();
     #endif
@@ -127,7 +137,7 @@ void mp_task(void *pvParameter) {
 soft_reset:
     // initialise the stack pointer for the main thread
     mp_stack_set_top((void *)sp);
-    mp_stack_set_limit(MP_TASK_STACK_SIZE - 1024);
+    mp_stack_set_limit(MP_TASK_STACK_SIZE - MP_TASK_STACK_LIMIT_MARGIN);
     gc_init(mp_task_heap, mp_task_heap + mp_task_heap_size);
     mp_init();
     mp_obj_list_init(mp_sys_path, 0);
@@ -138,6 +148,9 @@ soft_reset:
 
     // initialise peripherals
     machine_pins_init();
+    #if MICROPY_PY_MACHINE_I2S
+    machine_i2s_init0();
+    #endif
 
     // run boot-up scripts
     pyexec_frozen_module("_boot.py");
diff --git a/ports/esp32/main/CMakeLists.txt b/ports/esp32/main/CMakeLists.txt
index 7530e8420..c63e86d6c 100644
--- a/ports/esp32/main/CMakeLists.txt
+++ b/ports/esp32/main/CMakeLists.txt
@@ -15,21 +15,28 @@ set(MICROPY_QSTRDEFS_PORT
     ${PROJECT_DIR}/qstrdefsport.h
 )
 
+set(MICROPY_SOURCE_SHARED
+    ${MICROPY_DIR}/shared/readline/readline.c
+    ${MICROPY_DIR}/shared/netutils/netutils.c
+    ${MICROPY_DIR}/shared/timeutils/timeutils.c
+    ${MICROPY_DIR}/shared/runtime/interrupt_char.c
+    ${MICROPY_DIR}/shared/runtime/stdout_helpers.c
+    ${MICROPY_DIR}/shared/runtime/sys_stdio_mphal.c
+    ${MICROPY_DIR}/shared/runtime/pyexec.c
+)
+
 set(MICROPY_SOURCE_LIB
     ${MICROPY_DIR}/lib/littlefs/lfs1.c
     ${MICROPY_DIR}/lib/littlefs/lfs1_util.c
     ${MICROPY_DIR}/lib/littlefs/lfs2.c
     ${MICROPY_DIR}/lib/littlefs/lfs2_util.c
     ${MICROPY_DIR}/lib/mbedtls_errors/mp_mbedtls_errors.c
-    ${MICROPY_DIR}/lib/mp-readline/readline.c
-    ${MICROPY_DIR}/lib/netutils/netutils.c
     ${MICROPY_DIR}/lib/oofatfs/ff.c
     ${MICROPY_DIR}/lib/oofatfs/ffunicode.c
-    ${MICROPY_DIR}/lib/timeutils/timeutils.c
-    ${MICROPY_DIR}/lib/utils/interrupt_char.c
-    ${MICROPY_DIR}/lib/utils/sys_stdio_mphal.c
-    ${MICROPY_DIR}/lib/utils/pyexec.c
 )
+if(IDF_TARGET STREQUAL "esp32c3")
+    list(APPEND MICROPY_SOURCE_LIB ${MICROPY_DIR}/shared/runtime/gchelper_generic.c)
+endif()
 
 set(MICROPY_SOURCE_DRIVERS
     ${MICROPY_DIR}/drivers/bus/softspi.c
@@ -40,18 +47,21 @@ set(MICROPY_SOURCE_PORT
     ${PROJECT_DIR}/main.c
     ${PROJECT_DIR}/uart.c
     ${PROJECT_DIR}/usb.c
+    ${PROJECT_DIR}/usb_serial_jtag.c
     ${PROJECT_DIR}/gccollect.c
     ${PROJECT_DIR}/mphalport.c
     ${PROJECT_DIR}/fatfs_port.c
     ${PROJECT_DIR}/help.c
     ${PROJECT_DIR}/modutime.c
     ${PROJECT_DIR}/moduos.c
+    ${PROJECT_DIR}/machine_bitstream.c
     ${PROJECT_DIR}/machine_timer.c
     ${PROJECT_DIR}/machine_pin.c
     ${PROJECT_DIR}/machine_touchpad.c
     ${PROJECT_DIR}/machine_adc.c
     ${PROJECT_DIR}/machine_dac.c
     ${PROJECT_DIR}/machine_i2c.c
+    ${PROJECT_DIR}/machine_i2s.c
     ${PROJECT_DIR}/machine_pwm.c
     ${PROJECT_DIR}/machine_uart.c
     ${PROJECT_DIR}/modmachine.c
@@ -66,7 +76,6 @@ set(MICROPY_SOURCE_PORT
     ${PROJECT_DIR}/esp32_rmt.c
     ${PROJECT_DIR}/esp32_ulp.c
     ${PROJECT_DIR}/modesp32.c
-    ${PROJECT_DIR}/espneopixel.c
     ${PROJECT_DIR}/machine_hw_spi.c
     ${PROJECT_DIR}/machine_wdt.c
     ${PROJECT_DIR}/mpthreadport.c
@@ -83,6 +92,7 @@ set(MICROPY_SOURCE_QSTR
     ${MICROPY_SOURCE_PY}
     ${MICROPY_SOURCE_EXTMOD}
     ${MICROPY_SOURCE_USERMOD}
+    ${MICROPY_SOURCE_SHARED}
     ${MICROPY_SOURCE_LIB}
     ${MICROPY_SOURCE_PORT}
     ${LV_SRC}
@@ -136,6 +146,9 @@ endif()
 
 if(IDF_TARGET STREQUAL "esp32")
     list(APPEND IDF_COMPONENTS esp32)
+elseif(IDF_TARGET STREQUAL "esp32c3")
+    list(APPEND IDF_COMPONENTS esp32c3)
+    list(APPEND IDF_COMPONENTS riscv)
 elseif(IDF_TARGET STREQUAL "esp32s2")
     list(APPEND IDF_COMPONENTS esp32s2)
     list(APPEND IDF_COMPONENTS tinyusb)
@@ -149,6 +162,7 @@ idf_component_register(
     SRCS
         ${MICROPY_SOURCE_PY}
         ${MICROPY_SOURCE_EXTMOD}
+        ${MICROPY_SOURCE_SHARED}
         ${MICROPY_SOURCE_LIB}
         ${MICROPY_SOURCE_DRIVERS}
         ${MICROPY_SOURCE_PORT}
diff --git a/ports/esp32/makeimg.py b/ports/esp32/makeimg.py
index fd0458318..0646ce372 100644
--- a/ports/esp32/makeimg.py
+++ b/ports/esp32/makeimg.py
@@ -6,8 +6,17 @@ sys.path.append(os.getenv("IDF_PATH") + "/components/partition_table")
 
 import gen_esp32part
 
-OFFSET_BOOTLOADER = 0x1000
-OFFSET_PARTITIONS = 0x8000
+OFFSET_BOOTLOADER_DEFAULT = 0x1000
+OFFSET_PARTITIONS_DEFAULT = 0x8000
+
+
+def load_sdkconfig_hex_value(filename, value, default):
+    value = "CONFIG_" + value + "="
+    with open(filename, "r") as f:
+        for line in f:
+            if line.startswith(value):
+                return int(line.split("=", 1)[1], 16)
+    return default
 
 
 def load_partition_table(filename):
@@ -15,28 +24,47 @@ def load_partition_table(filename):
         return gen_esp32part.PartitionTable.from_binary(f.read())
 
 
-partition_table = load_partition_table(sys.argv[2])
+# Extract command-line arguments.
+arg_sdkconfig = sys.argv[1]
+arg_bootloader_bin = sys.argv[2]
+arg_partitions_bin = sys.argv[3]
+arg_application_bin = sys.argv[4]
+arg_output_bin = sys.argv[5]
 
-max_size_bootloader = OFFSET_PARTITIONS - OFFSET_BOOTLOADER
+# Load required sdkconfig values.
+offset_bootloader = load_sdkconfig_hex_value(
+    arg_sdkconfig, "BOOTLOADER_OFFSET_IN_FLASH", OFFSET_BOOTLOADER_DEFAULT
+)
+offset_partitions = load_sdkconfig_hex_value(
+    arg_sdkconfig, "PARTITION_TABLE_OFFSET", OFFSET_PARTITIONS_DEFAULT
+)
+
+# Load the partition table.
+partition_table = load_partition_table(arg_partitions_bin)
+
+max_size_bootloader = offset_partitions - offset_bootloader
 max_size_partitions = 0
 offset_application = 0
 max_size_application = 0
 
+# Inspect the partition table to find offsets and maximum sizes.
 for part in partition_table:
     if part.name == "nvs":
-        max_size_partitions = part.offset - OFFSET_PARTITIONS
+        max_size_partitions = part.offset - offset_partitions
     elif part.type == gen_esp32part.APP_TYPE and offset_application == 0:
         offset_application = part.offset
         max_size_application = part.size
 
+# Define the input files, their location and maximum size.
 files_in = [
-    ("bootloader", OFFSET_BOOTLOADER, max_size_bootloader, sys.argv[1]),
-    ("partitions", OFFSET_PARTITIONS, max_size_partitions, sys.argv[2]),
-    ("application", offset_application, max_size_application, sys.argv[3]),
+    ("bootloader", offset_bootloader, max_size_bootloader, arg_bootloader_bin),
+    ("partitions", offset_partitions, max_size_partitions, arg_partitions_bin),
+    ("application", offset_application, max_size_application, arg_application_bin),
 ]
-file_out = sys.argv[4]
+file_out = arg_output_bin
 
-cur_offset = OFFSET_BOOTLOADER
+# Write output file with combined firmware.
+cur_offset = offset_bootloader
 with open(file_out, "wb") as fout:
     for name, offset, max_size, file_in in files_in:
         assert offset >= cur_offset
diff --git a/ports/esp32/memory.h b/ports/esp32/memory.h
index f3777b0e3..1f07fe409 100644
--- a/ports/esp32/memory.h
+++ b/ports/esp32/memory.h
@@ -1,2 +1,2 @@
-// this is needed for extmod/crypto-algorithms/sha256.c
+// this is needed for lib/crypto-algorithms/sha256.c
 #include <string.h>
diff --git a/ports/esp32/modesp.c b/ports/esp32/modesp.c
index 59a261e8c..8c94e0cf4 100644
--- a/ports/esp32/modesp.c
+++ b/ports/esp32/modesp.c
@@ -112,15 +112,6 @@ STATIC mp_obj_t esp_gpio_matrix_out(size_t n_args, const mp_obj_t *args) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(esp_gpio_matrix_out_obj, 4, 4, esp_gpio_matrix_out);
 
-STATIC mp_obj_t esp_neopixel_write_(mp_obj_t pin, mp_obj_t buf, mp_obj_t timing) {
-    mp_buffer_info_t bufinfo;
-    mp_get_buffer_raise(buf, &bufinfo, MP_BUFFER_READ);
-    esp_neopixel_write(mp_hal_get_pin_obj(pin),
-        (uint8_t *)bufinfo.buf, bufinfo.len, mp_obj_get_int(timing));
-    return mp_const_none;
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_3(esp_neopixel_write_obj, esp_neopixel_write_);
-
 STATIC const mp_rom_map_elem_t esp_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_esp) },
 
@@ -135,7 +126,6 @@ STATIC const mp_rom_map_elem_t esp_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_gpio_matrix_in), MP_ROM_PTR(&esp_gpio_matrix_in_obj) },
     { MP_ROM_QSTR(MP_QSTR_gpio_matrix_out), MP_ROM_PTR(&esp_gpio_matrix_out_obj) },
 
-    { MP_ROM_QSTR(MP_QSTR_neopixel_write), MP_ROM_PTR(&esp_neopixel_write_obj) },
     { MP_ROM_QSTR(MP_QSTR_dht_readinto), MP_ROM_PTR(&dht_readinto_obj) },
 
     // Constants for second arg of osdebug()
@@ -153,4 +143,3 @@ const mp_obj_module_t esp_module = {
     .base = { &mp_type_module },
     .globals = (mp_obj_dict_t *)&esp_module_globals,
 };
-
diff --git a/ports/esp32/modesp32.c b/ports/esp32/modesp32.c
index 3ed534338..75e5b3ed8 100644
--- a/ports/esp32/modesp32.c
+++ b/ports/esp32/modesp32.c
@@ -30,7 +30,6 @@
 #include <time.h>
 #include <sys/time.h>
 #include "soc/rtc_cntl_reg.h"
-#include "soc/sens_reg.h"
 #include "driver/gpio.h"
 #include "driver/adc.h"
 #include "esp_heap_caps.h"
@@ -40,7 +39,7 @@
 #include "py/obj.h"
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "modmachine.h"
 #include "machine_rtc.h"
 #include "modesp32.h"
@@ -109,7 +108,7 @@ STATIC mp_obj_t esp32_wake_on_ext1(size_t n_args, const mp_obj_t *pos_args, mp_m
 
     // Check that all pins are allowed
     if (args[ARG_pins].u_obj != mp_const_none) {
-        mp_uint_t len = 0;
+        size_t len = 0;
         mp_obj_t *elem;
         mp_obj_get_array(args[ARG_pins].u_obj, &len, &elem);
         ext1_pins = 0;
@@ -134,6 +133,8 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_KW(esp32_wake_on_ext1_obj, 0, esp32_wake_on_ext1)
 
 #if CONFIG_IDF_TARGET_ESP32
 
+#include "soc/sens_reg.h"
+
 STATIC mp_obj_t esp32_raw_temperature(void) {
     SET_PERI_REG_BITS(SENS_SAR_MEAS_WAIT2_REG, SENS_FORCE_XPD_SAR, 3, SENS_FORCE_XPD_SAR_S);
     SET_PERI_REG_BITS(SENS_SAR_TSENS_CTRL_REG, SENS_TSENS_CLK_DIV, 10, SENS_TSENS_CLK_DIV_S);
diff --git a/ports/esp32/modmachine.c b/ports/esp32/modmachine.c
index bbe7fae03..5f94007d4 100644
--- a/ports/esp32/modmachine.c
+++ b/ports/esp32/modmachine.c
@@ -34,7 +34,6 @@
 #include "freertos/task.h"
 #include "esp_sleep.h"
 #include "esp_pm.h"
-#include "driver/touch_pad.h"
 
 #if CONFIG_IDF_TARGET_ESP32
 #include "esp32/rom/rtc.h"
@@ -49,7 +48,8 @@
 
 #include "py/obj.h"
 #include "py/runtime.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
+#include "extmod/machine_bitstream.h"
 #include "extmod/machine_mem.h"
 #include "extmod/machine_signal.h"
 #include "extmod/machine_pulse.h"
@@ -70,6 +70,10 @@ typedef enum {
 
 STATIC bool is_soft_reset = 0;
 
+#if CONFIG_IDF_TARGET_ESP32C3
+int esp_clk_cpu_freq(void);
+#endif
+
 STATIC mp_obj_t machine_freq(size_t n_args, const mp_obj_t *args) {
     if (n_args == 0) {
         // get
@@ -82,6 +86,8 @@ STATIC mp_obj_t machine_freq(size_t n_args, const mp_obj_t *args) {
         }
         #if CONFIG_IDF_TARGET_ESP32
         esp_pm_config_esp32_t pm;
+        #elif CONFIG_IDF_TARGET_ESP32C3
+        esp_pm_config_esp32c3_t pm;
         #elif CONFIG_IDF_TARGET_ESP32S2
         esp_pm_config_esp32s2_t pm;
         #endif
@@ -117,6 +123,8 @@ STATIC mp_obj_t machine_sleep_helper(wake_type_t wake_type, size_t n_args, const
         esp_sleep_enable_timer_wakeup(((uint64_t)expiry) * 1000);
     }
 
+    #if !CONFIG_IDF_TARGET_ESP32C3
+
     if (machine_rtc_config.ext0_pin != -1 && (machine_rtc_config.ext0_wake_types & wake_type)) {
         esp_sleep_enable_ext0_wakeup(machine_rtc_config.ext0_pin, machine_rtc_config.ext0_level ? 1 : 0);
     }
@@ -133,6 +141,8 @@ STATIC mp_obj_t machine_sleep_helper(wake_type_t wake_type, size_t n_args, const
         }
     }
 
+    #endif
+
     switch (wake_type) {
         case MACHINE_WAKE_SLEEP:
             esp_light_sleep_start();
@@ -223,7 +233,9 @@ STATIC mp_obj_t machine_unique_id(void) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(machine_unique_id_obj, machine_unique_id);
 
 STATIC mp_obj_t machine_idle(void) {
+    MP_THREAD_GIL_EXIT();
     taskYIELD();
+    MP_THREAD_GIL_ENTER();
     return mp_const_none;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(machine_idle_obj, machine_idle);
@@ -260,7 +272,12 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_disable_irq), MP_ROM_PTR(&machine_disable_irq_obj) },
     { MP_ROM_QSTR(MP_QSTR_enable_irq), MP_ROM_PTR(&machine_enable_irq_obj) },
 
+    #if MICROPY_PY_MACHINE_BITSTREAM
+    { MP_ROM_QSTR(MP_QSTR_bitstream), MP_ROM_PTR(&machine_bitstream_obj) },
+    #endif
+    #if MICROPY_PY_MACHINE_PULSE
     { MP_ROM_QSTR(MP_QSTR_time_pulse_us), MP_ROM_PTR(&machine_time_pulse_us_obj) },
+    #endif
 
     { MP_ROM_QSTR(MP_QSTR_Timer), MP_ROM_PTR(&machine_timer_type) },
     { MP_ROM_QSTR(MP_QSTR_WDT), MP_ROM_PTR(&machine_wdt_type) },
@@ -277,9 +294,14 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_TouchPad), MP_ROM_PTR(&machine_touchpad_type) },
     #endif
     { MP_ROM_QSTR(MP_QSTR_ADC), MP_ROM_PTR(&machine_adc_type) },
+    #if MICROPY_PY_MACHINE_DAC
     { MP_ROM_QSTR(MP_QSTR_DAC), MP_ROM_PTR(&machine_dac_type) },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_I2C), MP_ROM_PTR(&machine_hw_i2c_type) },
     { MP_ROM_QSTR(MP_QSTR_SoftI2C), MP_ROM_PTR(&mp_machine_soft_i2c_type) },
+    #if MICROPY_PY_MACHINE_I2S
+    { MP_ROM_QSTR(MP_QSTR_I2S), MP_ROM_PTR(&machine_i2s_type) },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_PWM), MP_ROM_PTR(&machine_pwm_type) },
     { MP_ROM_QSTR(MP_QSTR_RTC), MP_ROM_PTR(&machine_rtc_type) },
     { MP_ROM_QSTR(MP_QSTR_SPI), MP_ROM_PTR(&machine_hw_spi_type) },
diff --git a/ports/esp32/modmachine.h b/ports/esp32/modmachine.h
index 3e99e1120..7bf03b0ca 100644
--- a/ports/esp32/modmachine.h
+++ b/ports/esp32/modmachine.h
@@ -18,6 +18,7 @@ extern const mp_obj_type_t machine_dac_type;
 extern const mp_obj_type_t machine_pwm_type;
 extern const mp_obj_type_t machine_hw_i2c_type;
 extern const mp_obj_type_t machine_hw_spi_type;
+extern const mp_obj_type_t machine_i2s_type;
 extern const mp_obj_type_t machine_uart_type;
 extern const mp_obj_type_t machine_rtc_type;
 extern const mp_obj_type_t machine_sdcard_type;
@@ -27,5 +28,6 @@ void machine_deinit(void);
 void machine_pins_init(void);
 void machine_pins_deinit(void);
 void machine_timer_deinit_all(void);
+void machine_i2s_init0();
 
 #endif // MICROPY_INCLUDED_ESP32_MODMACHINE_H
diff --git a/ports/esp32/modnetwork.c b/ports/esp32/modnetwork.c
index e2bd20a1a..2b64105e7 100644
--- a/ports/esp32/modnetwork.c
+++ b/ports/esp32/modnetwork.c
@@ -40,7 +40,7 @@
 #include "py/runtime.h"
 #include "py/mphal.h"
 #include "py/mperrno.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "esp_eth.h"
 #include "esp_wifi.h"
 #include "esp_log.h"
@@ -466,7 +466,7 @@ STATIC mp_obj_t esp_scan(mp_obj_t self_in) {
 
     mp_obj_t list = mp_obj_new_list(0, NULL);
     wifi_scan_config_t config = { 0 };
-    // XXX how do we scan hidden APs (and if we can scan them, are they really hidden?)
+    config.show_hidden = true;
     MP_THREAD_GIL_EXIT();
     esp_err_t status = esp_wifi_scan_start(&config, 1);
     MP_THREAD_GIL_ENTER();
diff --git a/ports/esp32/modsocket.c b/ports/esp32/modsocket.c
index 67b1d7d6f..be950ac1f 100644
--- a/ports/esp32/modsocket.c
+++ b/ports/esp32/modsocket.c
@@ -45,7 +45,7 @@
 #include "py/mphal.h"
 #include "py/stream.h"
 #include "py/mperrno.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "mdns.h"
 #include "modnetwork.h"
 
diff --git a/ports/esp32/modules/neopixel.py b/ports/esp32/modules/neopixel.py
deleted file mode 100644
index f5c919398..000000000
--- a/ports/esp32/modules/neopixel.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# NeoPixel driver for MicroPython on ESP32
-# MIT license; Copyright (c) 2016 Damien P. George
-
-from esp import neopixel_write
-
-
-class NeoPixel:
-    ORDER = (1, 0, 2, 3)
-
-    def __init__(self, pin, n, bpp=3, timing=1):
-        self.pin = pin
-        self.n = n
-        self.bpp = bpp
-        self.buf = bytearray(n * bpp)
-        self.pin.init(pin.OUT)
-        self.timing = timing
-
-    def __len__(self):
-        return self.n
-
-    def __setitem__(self, index, val):
-        offset = index * self.bpp
-        for i in range(self.bpp):
-            self.buf[offset + self.ORDER[i]] = val[i]
-
-    def __getitem__(self, index):
-        offset = index * self.bpp
-        return tuple(self.buf[offset + self.ORDER[i]] for i in range(self.bpp))
-
-    def fill(self, color):
-        for i in range(self.n):
-            self[i] = color
-
-    def write(self):
-        neopixel_write(self.pin, self.buf, self.timing)
diff --git a/ports/esp32/modutime.c b/ports/esp32/modutime.c
index cf7178e0b..f864df678 100644
--- a/ports/esp32/modutime.c
+++ b/ports/esp32/modutime.c
@@ -31,7 +31,7 @@
 #include <sys/time.h>
 
 #include "py/runtime.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "extmod/utime_mphal.h"
 
 STATIC mp_obj_t time_localtime(size_t n_args, const mp_obj_t *args) {
diff --git a/ports/esp32/mpconfigport.h b/ports/esp32/mpconfigport.h
index c6af43a67..75b00eadb 100644
--- a/ports/esp32/mpconfigport.h
+++ b/ports/esp32/mpconfigport.h
@@ -11,13 +11,18 @@
 // object representation and NLR handling
 #define MICROPY_OBJ_REPR                    (MICROPY_OBJ_REPR_A)
 #define MICROPY_NLR_SETJMP                  (1)
+#if CONFIG_IDF_TARGET_ESP32C3
+#define MICROPY_GCREGS_SETJMP               (1)
+#endif
 
 // memory allocation policies
 #define MICROPY_ALLOC_PATH_MAX              (128)
 
 // emitters
 #define MICROPY_PERSISTENT_CODE_LOAD        (1)
+#if !CONFIG_IDF_TARGET_ESP32C3
 #define MICROPY_EMIT_XTENSAWIN              (1)
+#endif
 
 // compiler configuration
 #define MICROPY_COMP_MODULE_CONST           (1)
@@ -61,6 +66,7 @@
 #define MICROPY_PY_FUNCTION_ATTRS           (1)
 #define MICROPY_PY_DESCRIPTORS              (1)
 #define MICROPY_PY_DELATTR_SETATTR          (1)
+#define MICROPY_PY_FSTRINGS                 (1)
 #define MICROPY_PY_STR_BYTES_CMP_WARN       (1)
 #define MICROPY_PY_BUILTINS_STR_UNICODE     (1)
 #define MICROPY_PY_BUILTINS_STR_CENTER      (1)
@@ -77,6 +83,8 @@
 #define MICROPY_PY_BUILTINS_RANGE_ATTRS     (1)
 #define MICROPY_PY_BUILTINS_ROUND_INT       (1)
 #define MICROPY_PY_ALL_SPECIAL_METHODS      (1)
+#define MICROPY_PY_ALL_INPLACE_SPECIAL_METHODS (1)
+#define MICROPY_PY_REVERSE_SPECIAL_METHODS  (1)
 #define MICROPY_PY_BUILTINS_COMPILE         (1)
 #define MICROPY_PY_BUILTINS_ENUMERATE       (1)
 #define MICROPY_PY_BUILTINS_EXECFILE        (1)
@@ -148,11 +156,18 @@
 #define MICROPY_PY_OS_DUPTERM               (1)
 #define MICROPY_PY_MACHINE                  (1)
 #define MICROPY_PY_MACHINE_PIN_MAKE_NEW     mp_pin_make_new
+#define MICROPY_PY_MACHINE_BITSTREAM        (1)
 #define MICROPY_PY_MACHINE_PULSE            (1)
 #define MICROPY_PY_MACHINE_I2C              (1)
 #define MICROPY_PY_MACHINE_SPI              (1)
 #define MICROPY_PY_MACHINE_SPI_MSB          (0)
 #define MICROPY_PY_MACHINE_SPI_LSB          (1)
+#ifndef MICROPY_PY_MACHINE_DAC
+#define MICROPY_PY_MACHINE_DAC              (1)
+#endif
+#ifndef MICROPY_PY_MACHINE_I2S
+#define MICROPY_PY_MACHINE_I2S              (1)
+#endif
 #ifndef MICROPY_HW_ENABLE_SDCARD
 #define MICROPY_HW_ENABLE_SDCARD            (1)
 #endif
diff --git a/ports/esp32/mphalport.c b/ports/esp32/mphalport.c
index a0bafb755..de1b173ac 100644
--- a/ports/esp32/mphalport.c
+++ b/ports/esp32/mphalport.c
@@ -35,6 +35,8 @@
 
 #if CONFIG_IDF_TARGET_ESP32
 #include "esp32/rom/uart.h"
+#elif CONFIG_IDF_TARGET_ESP32C3
+#include "esp32c3/rom/uart.h"
 #elif CONFIG_IDF_TARGET_ESP32S2
 #include "esp32s2/rom/uart.h"
 #elif CONFIG_IDF_TARGET_ESP32S3
@@ -47,10 +49,11 @@
 #include "py/mpstate.h"
 #include "py/mphal.h"
 #include "extmod/misc.h"
-#include "lib/timeutils/timeutils.h"
-#include "lib/utils/pyexec.h"
+#include "shared/timeutils/timeutils.h"
+#include "shared/runtime/pyexec.h"
 #include "mphalport.h"
 #include "usb.h"
+#include "usb_serial_jtag.h"
 
 TaskHandle_t mp_main_task_handle;
 
@@ -108,11 +111,7 @@ int mp_hal_stdin_rx_chr(void) {
     }
 }
 
-void mp_hal_stdout_tx_str(const char *str) {
-    mp_hal_stdout_tx_strn(str, strlen(str));
-}
-
-void mp_hal_stdout_tx_strn(const char *str, uint32_t len) {
+void mp_hal_stdout_tx_strn(const char *str, size_t len) {
     // Only release the GIL if many characters are being sent
     bool release_gil = len > 20;
     if (release_gil) {
@@ -120,6 +119,8 @@ void mp_hal_stdout_tx_strn(const char *str, uint32_t len) {
     }
     #if CONFIG_USB_ENABLED
     usb_tx_strn(str, len);
+    #elif CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
+    usb_serial_jtag_tx_strn(str, len);
     #else
     for (uint32_t i = 0; i < len; ++i) {
         uart_tx_one_char(str[i]);
@@ -131,26 +132,6 @@ void mp_hal_stdout_tx_strn(const char *str, uint32_t len) {
     mp_uos_dupterm_tx_strn(str, len);
 }
 
-// Efficiently convert "\n" to "\r\n"
-void mp_hal_stdout_tx_strn_cooked(const char *str, size_t len) {
-    const char *last = str;
-    while (len--) {
-        if (*str == '\n') {
-            if (str > last) {
-                mp_hal_stdout_tx_strn(last, str - last);
-            }
-            mp_hal_stdout_tx_strn("\r\n", 2);
-            ++str;
-            last = str;
-        } else {
-            ++str;
-        }
-    }
-    if (str > last) {
-        mp_hal_stdout_tx_strn(last, str - last);
-    }
-}
-
 uint32_t mp_hal_ticks_ms(void) {
     return esp_timer_get_time() / 1000;
 }
@@ -164,14 +145,22 @@ void mp_hal_delay_ms(uint32_t ms) {
     uint64_t dt;
     uint64_t t0 = esp_timer_get_time();
     for (;;) {
+        mp_handle_pending(true);
+        MICROPY_PY_USOCKET_EVENTS_HANDLER
+        MP_THREAD_GIL_EXIT();
         uint64_t t1 = esp_timer_get_time();
         dt = t1 - t0;
         if (dt + portTICK_PERIOD_MS * 1000 >= us) {
             // doing a vTaskDelay would take us beyond requested delay time
+            taskYIELD();
+            MP_THREAD_GIL_ENTER();
+            t1 = esp_timer_get_time();
+            dt = t1 - t0;
             break;
+        } else {
+            ulTaskNotifyTake(pdFALSE, 1);
+            MP_THREAD_GIL_ENTER();
         }
-        MICROPY_EVENT_POLL_HOOK
-        ulTaskNotifyTake(pdFALSE, 1);
     }
     if (dt < us) {
         // do the remaining delay accurately
diff --git a/ports/esp32/mphalport.h b/ports/esp32/mphalport.h
index 60cc308d6..2dad8fa92 100644
--- a/ports/esp32/mphalport.h
+++ b/ports/esp32/mphalport.h
@@ -30,7 +30,7 @@
 #define INCLUDED_MPHALPORT_H
 
 #include "py/ringbuf.h"
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
@@ -51,7 +51,11 @@ void check_esp_err(esp_err_t code);
 uint32_t mp_hal_ticks_us(void);
 __attribute__((always_inline)) static inline uint32_t mp_hal_ticks_cpu(void) {
     uint32_t ccount;
+    #if CONFIG_IDF_TARGET_ESP32C3
+    __asm__ __volatile__ ("csrr %0, 0x7E2" : "=r" (ccount)); // Machine Performance Counter Value
+    #else
     __asm__ __volatile__ ("rsr %0,ccount" : "=a" (ccount));
+    #endif
     return ccount;
 }
 
diff --git a/ports/esp32/network_ppp.c b/ports/esp32/network_ppp.c
index db2292ca0..d74283c19 100644
--- a/ports/esp32/network_ppp.c
+++ b/ports/esp32/network_ppp.c
@@ -30,7 +30,7 @@
 #include "py/mphal.h"
 #include "py/objtype.h"
 #include "py/stream.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "modmachine.h"
 
 #include "netif/ppp/ppp.h"
diff --git a/ports/esp32/partitions-16MiB-ota.csv b/ports/esp32/partitions-16MiB-ota.csv
new file mode 100644
index 000000000..a6f83bc46
--- /dev/null
+++ b/ports/esp32/partitions-16MiB-ota.csv
@@ -0,0 +1,10 @@
+# Partition table for MicroPython with OTA support using 16MB flash
+# Notes: the offset of the partition table itself is set in
+# $IDF_PATH/components/partition_table/Kconfig.projbuild.
+# Name,   Type, SubType, Offset,   Size,     Flags
+nvs,      data, nvs,     0x9000,   0x4000,
+otadata,  data, ota,     0xd000,   0x2000,
+phy_init, data, phy,     0xf000,   0x1000,
+ota_0,    app,  ota_0,   0x10000,  0x270000,
+ota_1,    app,  ota_1,   0x280000, 0x270000,
+vfs,      data, fat,     0x4f0000, 0xb10000,
diff --git a/ports/esp32/uart.c b/ports/esp32/uart.c
index c4fe41eaf..480b364a5 100644
--- a/ports/esp32/uart.c
+++ b/ports/esp32/uart.c
@@ -51,7 +51,7 @@ STATIC void IRAM_ATTR uart_irq_handler(void *arg) {
     while (uart->status.rxfifo_cnt) {
         #if CONFIG_IDF_TARGET_ESP32
         uint8_t c = uart->fifo.rw_byte;
-        #elif CONFIG_IDF_TARGET_ESP32S2
+        #elif CONFIG_IDF_TARGET_ESP32C3 || CONFIG_IDF_TARGET_ESP32S2
         uint8_t c = READ_PERI_REG(UART_FIFO_AHB_REG(0)); // UART0
         #endif
         if (c == mp_interrupt_char) {
diff --git a/ports/esp32/usb_serial_jtag.c b/ports/esp32/usb_serial_jtag.c
new file mode 100644
index 000000000..a7d06a355
--- /dev/null
+++ b/ports/esp32/usb_serial_jtag.c
@@ -0,0 +1,98 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Patrick Van Oosterwijck
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "usb_serial_jtag.h"
+
+#if CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
+
+#include "hal/usb_serial_jtag_ll.h"
+#include "esp_intr_alloc.h"
+#include "soc/periph_defs.h"
+
+#define USB_SERIAL_JTAG_BUF_SIZE (64)
+
+static uint8_t rx_buf[USB_SERIAL_JTAG_BUF_SIZE];
+static volatile bool terminal_connected = false;
+
+static void usb_serial_jtag_isr_handler(void *arg) {
+    uint32_t flags = usb_serial_jtag_ll_get_intsts_mask();
+
+    if (flags & USB_SERIAL_JTAG_INTR_SOF) {
+        usb_serial_jtag_ll_clr_intsts_mask(USB_SERIAL_JTAG_INTR_SOF);
+    }
+
+    if (flags & USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT) {
+        usb_serial_jtag_ll_clr_intsts_mask(USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT);
+        size_t req_len = ringbuf_free(&stdin_ringbuf);
+        if (req_len > USB_SERIAL_JTAG_BUF_SIZE) {
+            req_len = USB_SERIAL_JTAG_BUF_SIZE;
+        }
+        size_t len = usb_serial_jtag_ll_read_rxfifo(rx_buf, req_len);
+        for (size_t i = 0; i < len; ++i) {
+            if (rx_buf[i] == mp_interrupt_char) {
+                mp_sched_keyboard_interrupt();
+            } else {
+                ringbuf_put(&stdin_ringbuf, rx_buf[i]);
+            }
+        }
+        mp_hal_wake_main_task_from_isr();
+    }
+}
+
+void usb_serial_jtag_init(void) {
+    usb_serial_jtag_ll_clr_intsts_mask(USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT |
+        USB_SERIAL_JTAG_INTR_SOF);
+    usb_serial_jtag_ll_ena_intr_mask(USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT |
+        USB_SERIAL_JTAG_INTR_SOF);
+    ESP_ERROR_CHECK(esp_intr_alloc(ETS_USB_SERIAL_JTAG_INTR_SOURCE, ESP_INTR_FLAG_LEVEL1,
+        usb_serial_jtag_isr_handler, NULL, NULL));
+}
+
+void usb_serial_jtag_tx_strn(const char *str, size_t len) {
+    while (len) {
+        size_t l = len;
+        if (l > USB_SERIAL_JTAG_PACKET_SZ_BYTES) {
+            l = USB_SERIAL_JTAG_PACKET_SZ_BYTES;
+        }
+        portTickType start_tick = xTaskGetTickCount();
+        while (!usb_serial_jtag_ll_txfifo_writable()) {
+            portTickType now_tick = xTaskGetTickCount();
+            if (!terminal_connected || now_tick > (start_tick + pdMS_TO_TICKS(200))) {
+                terminal_connected = false;
+                return;
+            }
+        }
+        terminal_connected = true;
+        l = usb_serial_jtag_ll_write_txfifo((const uint8_t *)str, l);
+        usb_serial_jtag_ll_txfifo_flush();
+        str += l;
+        len -= l;
+    }
+}
+
+#endif // CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
diff --git a/ports/esp32/usb_serial_jtag.h b/ports/esp32/usb_serial_jtag.h
new file mode 100644
index 000000000..4eebb19e4
--- /dev/null
+++ b/ports/esp32/usb_serial_jtag.h
@@ -0,0 +1,32 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Patrick Van Oosterwijck
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_ESP32_USB_SERIAL_JTAG_H
+#define MICROPY_INCLUDED_ESP32_USB_SERIAL_JTAG_H
+
+void usb_serial_jtag_init(void);
+void usb_serial_jtag_tx_strn(const char *str, size_t len);
+
+#endif // MICROPY_INCLUDED_ESP32_USB_SERIAL_JTAG_H
diff --git a/ports/esp8266/Makefile b/ports/esp8266/Makefile
index 02ea05f76..9ea4498f4 100644
--- a/ports/esp8266/Makefile
+++ b/ports/esp8266/Makefile
@@ -91,10 +91,10 @@ SRC_C = \
 	lexerstr32.c \
 	uart.c \
 	esppwm.c \
-	espneopixel.c \
 	espapa102.c \
 	modpyb.c \
 	modmachine.c \
+	machine_bitstream.c \
 	machine_pin.c \
 	machine_pwm.c \
 	machine_rtc.c \
@@ -119,33 +119,45 @@ EXTMOD_SRC_C = $(addprefix extmod/,\
         )
 
 LIB_SRC_C = $(addprefix lib/,\
-	embed/__errno.c \
-	libc/string0.c \
 	libm/math.c \
 	libm/fmodf.c \
 	libm/nearbyintf.c \
 	libm/ef_sqrt.c \
+	libm/erf_lgamma.c \
 	libm/kf_rem_pio2.c \
 	libm/kf_sin.c \
 	libm/kf_cos.c \
 	libm/kf_tan.c \
 	libm/ef_rem_pio2.c \
+	libm/sf_erf.c \
 	libm/sf_sin.c \
 	libm/sf_cos.c \
 	libm/sf_tan.c \
 	libm/sf_frexp.c \
 	libm/sf_modf.c \
 	libm/sf_ldexp.c \
+	libm/acoshf.c \
 	libm/asinfacosf.c \
+	libm/asinhf.c \
 	libm/atanf.c \
+	libm/atanhf.c \
 	libm/atan2f.c \
+	libm/log1pf.c \
 	libm/roundf.c \
-	mp-readline/readline.c \
+	libm/wf_lgamma.c \
+	libm/wf_tgamma.c \
+	)
+
+SHARED_SRC_C = $(addprefix shared/,\
+	libc/__errno.c \
+	libc/string0.c \
 	netutils/netutils.c \
+	readline/readline.c \
+	runtime/interrupt_char.c \
+	runtime/pyexec.c \
+	runtime/stdout_helpers.c \
+	runtime/sys_stdio_mphal.c \
 	timeutils/timeutils.c \
-	utils/pyexec.c \
-	utils/interrupt_char.c \
-	utils/sys_stdio_mphal.c \
 	)
 
 DRIVERS_SRC_C = $(addprefix drivers/,\
@@ -161,11 +173,12 @@ OBJ += $(PY_O)
 OBJ += $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_S:.s=.o))
 OBJ += $(addprefix $(BUILD)/, $(EXTMOD_SRC_C:.c=.o))
+OBJ += $(addprefix $(BUILD)/, $(SHARED_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(LIB_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(DRIVERS_SRC_C:.c=.o))
 
 # List of sources for qstr extraction
-SRC_QSTR += $(SRC_C) $(EXTMOD_SRC_C) $(LIB_SRC_C) $(DRIVERS_SRC_C)
+SRC_QSTR += $(SRC_C) $(EXTMOD_SRC_C) $(SHARED_SRC_C) $(DRIVERS_SRC_C)
 # Append any auto-generated sources that are needed by sources listed in SRC_QSTR
 SRC_QSTR_AUTO_DEPS +=
 
diff --git a/ports/esp8266/boards/GENERIC_512K/manifest.py b/ports/esp8266/boards/GENERIC_512K/manifest.py
index 5674f280b..ee148c808 100644
--- a/ports/esp8266/boards/GENERIC_512K/manifest.py
+++ b/ports/esp8266/boards/GENERIC_512K/manifest.py
@@ -1,5 +1,6 @@
 freeze("$(BOARD_DIR)", "_boot.py", opt=3)
-freeze("$(PORT_DIR)/modules", ("apa102.py", "neopixel.py", "ntptime.py", "port_diag.py"))
+freeze("$(PORT_DIR)/modules", ("apa102.py", "ntptime.py", "port_diag.py"))
 freeze("$(MPY_DIR)/drivers/dht", "dht.py")
 freeze("$(MPY_DIR)/drivers/onewire")
 include("$(MPY_DIR)/extmod/webrepl/manifest.py")
+include("$(MPY_DIR)/drivers/neopixel/manifest.py")
diff --git a/ports/esp8266/boards/esp8266_common.ld b/ports/esp8266/boards/esp8266_common.ld
index c6e37d942..f40ff1e5f 100644
--- a/ports/esp8266/boards/esp8266_common.ld
+++ b/ports/esp8266/boards/esp8266_common.ld
@@ -134,14 +134,14 @@ SECTIONS
         *lib/berkeley-db-1.xx/*.o(.literal*, .text*)
         *lib/libm/*.o*(.literal*, .text*)
         *lib/littlefs/*.o*(.literal*, .text*)
-        *lib/mp-readline/*.o(.literal*, .text*)
-        *lib/netutils/*.o*(.literal*, .text*)
-        *lib/timeutils/*.o*(.literal*, .text*)
-        *lib/utils/printf.o*(.literal*, .text*)
-        *lib/utils/sys_stdio_mphal.o*(.literal*, .text*)
-        *lib/utils/pyexec.o*(.literal*, .text*)
-        *lib/utils/stdout_helpers.o*(.literal*, .text*)
-        *lib/utils/interrupt_char.o*(.literal*, .text*)
+        *shared/libc/printf.o*(.literal*, .text*)
+        *shared/netutils/*.o*(.literal*, .text*)
+        *shared/readline/*.o(.literal*, .text*)
+        *shared/runtime/interrupt_char.o*(.literal*, .text*)
+        *shared/runtime/pyexec.o*(.literal*, .text*)
+        *shared/runtime/stdout_helpers.o*(.literal*, .text*)
+        *shared/runtime/sys_stdio_mphal.o*(.literal*, .text*)
+        *shared/timeutils/*.o*(.literal*, .text*)
         *drivers/bus/*.o(.literal* .text*)
 
         build-*/main.o(.literal* .text*)
diff --git a/ports/esp8266/boards/manifest.py b/ports/esp8266/boards/manifest.py
index de719f8f1..598572d62 100644
--- a/ports/esp8266/boards/manifest.py
+++ b/ports/esp8266/boards/manifest.py
@@ -3,3 +3,4 @@ freeze("$(MPY_DIR)/tools", ("upip.py", "upip_utarfile.py"))
 freeze("$(MPY_DIR)/drivers/dht", "dht.py")
 freeze("$(MPY_DIR)/drivers/onewire")
 include("$(MPY_DIR)/extmod/webrepl/manifest.py")
+include("$(MPY_DIR)/drivers/neopixel/manifest.py")
diff --git a/ports/esp8266/esp_mphal.c b/ports/esp8266/esp_mphal.c
index 54f9611e5..3cb480733 100644
--- a/ports/esp8266/esp_mphal.c
+++ b/ports/esp8266/esp_mphal.c
@@ -34,7 +34,7 @@
 #include "py/runtime.h"
 #include "py/stream.h"
 #include "extmod/misc.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 
 STATIC byte stdin_ringbuf_array[256];
 ringbuf_t stdin_ringbuf = {stdin_ringbuf_array, sizeof(stdin_ringbuf_array), 0, 0};
@@ -91,33 +91,10 @@ void mp_hal_debug_str(const char *str) {
 }
 #endif
 
-void mp_hal_stdout_tx_str(const char *str) {
-    mp_uos_dupterm_tx_strn(str, strlen(str));
-}
-
 void mp_hal_stdout_tx_strn(const char *str, uint32_t len) {
     mp_uos_dupterm_tx_strn(str, len);
 }
 
-void mp_hal_stdout_tx_strn_cooked(const char *str, uint32_t len) {
-    const char *last = str;
-    while (len--) {
-        if (*str == '\n') {
-            if (str > last) {
-                mp_uos_dupterm_tx_strn(last, str - last);
-            }
-            mp_uos_dupterm_tx_strn("\r\n", 2);
-            ++str;
-            last = str;
-        } else {
-            ++str;
-        }
-    }
-    if (str > last) {
-        mp_uos_dupterm_tx_strn(last, str - last);
-    }
-}
-
 void mp_hal_debug_tx_strn_cooked(void *env, const char *str, uint32_t len) {
     (void)env;
     while (len--) {
diff --git a/ports/esp8266/esp_mphal.h b/ports/esp8266/esp_mphal.h
index e9cf7e548..b0351877e 100644
--- a/ports/esp8266/esp_mphal.h
+++ b/ports/esp8266/esp_mphal.h
@@ -26,7 +26,7 @@
 
 #include "user_interface.h"
 #include "py/ringbuf.h"
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 #include "xtirq.h"
 
 void mp_sched_keyboard_interrupt(void);
diff --git a/ports/esp8266/espneopixel.c b/ports/esp8266/espneopixel.c
deleted file mode 100644
index d2166a8b0..000000000
--- a/ports/esp8266/espneopixel.c
+++ /dev/null
@@ -1,75 +0,0 @@
-// Original version from https://github.com/adafruit/Adafruit_NeoPixel
-// Modifications by dpgeorge to support auto-CPU-frequency detection
-
-// This is a mash-up of the Due show() code + insights from Michael Miller's
-// ESP8266 work for the NeoPixelBus library: github.com/Makuna/NeoPixelBus
-// Needs to be a separate .c file to enforce ICACHE_RAM_ATTR execution.
-
-#include "py/mpconfig.h"
-#if MICROPY_ESP8266_NEOPIXEL
-
-#include "c_types.h"
-#include "eagle_soc.h"
-#include "user_interface.h"
-#include "espneopixel.h"
-#include "esp_mphal.h"
-
-#define NEO_KHZ400 (1)
-
-void /*ICACHE_RAM_ATTR*/ esp_neopixel_write(uint8_t pin, uint8_t *pixels, uint32_t numBytes, bool is800KHz) {
-
-    uint8_t *p, *end, pix, mask;
-    uint32_t t, time0, time1, period, c, startTime, pinMask;
-
-    pinMask = 1 << pin;
-    p = pixels;
-    end = p + numBytes;
-    pix = *p++;
-    mask = 0x80;
-    startTime = 0;
-
-    uint32_t fcpu = system_get_cpu_freq() * 1000000;
-
-    #ifdef NEO_KHZ400
-    if (is800KHz) {
-    #endif
-    time0 = fcpu / 2857143;  // 0.35us
-    time1 = fcpu / 1250000;  // 0.8us
-    period = fcpu / 800000;  // 1.25us per bit
-    #ifdef NEO_KHZ400
-} else {   // 400 KHz bitstream
-    time0 = fcpu / 2000000;  // 0.5uS
-    time1 = fcpu / 833333;   // 1.2us
-    period = fcpu / 400000;  // 2.5us per bit
-}
-    #endif
-
-    uint32_t irq_state = mp_hal_quiet_timing_enter();
-    for (t = time0;; t = time0) {
-        if (pix & mask) {
-            t = time1;                                    // Bit high duration
-        }
-        while (((c = mp_hal_ticks_cpu()) - startTime) < period) {
-            ;                                               // Wait for bit start
-        }
-        GPIO_REG_WRITE(GPIO_OUT_W1TS_ADDRESS, pinMask);   // Set high
-        startTime = c;                                    // Save start time
-        while (((c = mp_hal_ticks_cpu()) - startTime) < t) {
-            ;                                               // Wait high duration
-        }
-        GPIO_REG_WRITE(GPIO_OUT_W1TC_ADDRESS, pinMask);   // Set low
-        if (!(mask >>= 1)) {                              // Next bit/byte
-            if (p >= end) {
-                break;
-            }
-            pix = *p++;
-            mask = 0x80;
-        }
-    }
-    while ((mp_hal_ticks_cpu() - startTime) < period) {
-        ;                                           // Wait for last bit
-    }
-    mp_hal_quiet_timing_exit(irq_state);
-}
-
-#endif // MICROPY_ESP8266_NEOPIXEL
diff --git a/ports/esp8266/espneopixel.h b/ports/esp8266/espneopixel.h
deleted file mode 100644
index c444740ff..000000000
--- a/ports/esp8266/espneopixel.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#ifndef MICROPY_INCLUDED_ESP8266_ESPNEOPIXEL_H
-#define MICROPY_INCLUDED_ESP8266_ESPNEOPIXEL_H
-
-void esp_neopixel_write(uint8_t pin, uint8_t *pixels, uint32_t numBytes, bool is800KHz);
-
-#endif // MICROPY_INCLUDED_ESP8266_ESPNEOPIXEL_H
diff --git a/ports/esp8266/fatfs_port.c b/ports/esp8266/fatfs_port.c
index bbd105193..3ffc90040 100644
--- a/ports/esp8266/fatfs_port.c
+++ b/ports/esp8266/fatfs_port.c
@@ -25,7 +25,7 @@
  */
 
 #include "py/obj.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "lib/oofatfs/ff.h"
 #include "modmachine.h"
 
diff --git a/ports/esp8266/machine_bitstream.c b/ports/esp8266/machine_bitstream.c
new file mode 100644
index 000000000..13666f3d0
--- /dev/null
+++ b/ports/esp8266/machine_bitstream.c
@@ -0,0 +1,74 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Jim Mussared
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+// This is slightly modified from the implementation in ports/esp32/machine_bitstream.c.
+
+#include "py/mpconfig.h"
+#include "py/mphal.h"
+
+#if MICROPY_PY_MACHINE_BITSTREAM
+
+#define NS_TICKS_OVERHEAD (8)
+
+void machine_bitstream_high_low(mp_hal_pin_obj_t pin, uint32_t *timing_ns, const uint8_t *buf, size_t len) {
+    uint32_t pin_mask = 1 << pin;
+
+    // Convert ns to cpu ticks [high_time_0, period_0, high_time_1, period_1].
+    uint32_t fcpu_mhz = system_get_cpu_freq();
+    for (size_t i = 0; i < 4; ++i) {
+        timing_ns[i] = fcpu_mhz * timing_ns[i] / 1000;
+        if (timing_ns[i] > NS_TICKS_OVERHEAD) {
+            timing_ns[i] -= NS_TICKS_OVERHEAD;
+        }
+        if (i % 2 == 1) {
+            // Convert low_time to period (i.e. add high_time).
+            timing_ns[i] += timing_ns[i - 1];
+        }
+    }
+
+    uint32_t irq_state = mp_hal_quiet_timing_enter();
+
+    for (size_t i = 0; i < len; ++i) {
+        uint8_t b = buf[i];
+        for (size_t j = 0; j < 8; ++j) {
+            GPIO_REG_WRITE(GPIO_OUT_W1TS_ADDRESS, pin_mask);
+            uint32_t start_ticks = mp_hal_ticks_cpu();
+            uint32_t *t = &timing_ns[b >> 6 & 2];
+            while (mp_hal_ticks_cpu() - start_ticks < t[0]) {
+                ;
+            }
+            GPIO_REG_WRITE(GPIO_OUT_W1TC_ADDRESS, pin_mask);
+            b <<= 1;
+            while (mp_hal_ticks_cpu() - start_ticks < t[1]) {
+                ;
+            }
+        }
+    }
+
+    mp_hal_quiet_timing_exit(irq_state);
+}
+
+#endif // MICROPY_PY_MACHINE_BITSTREAM
diff --git a/ports/esp8266/machine_rtc.c b/ports/esp8266/machine_rtc.c
index e7b750fd9..38049ce72 100644
--- a/ports/esp8266/machine_rtc.c
+++ b/ports/esp8266/machine_rtc.c
@@ -28,7 +28,7 @@
 #include <string.h>
 
 #include "py/runtime.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "user_interface.h"
 #include "modmachine.h"
 
diff --git a/ports/esp8266/main.c b/ports/esp8266/main.c
index a73fbbcf5..404188346 100644
--- a/ports/esp8266/main.c
+++ b/ports/esp8266/main.c
@@ -39,8 +39,8 @@
 #define USE_US_TIMER 1
 
 #include "extmod/misc.h"
-#include "lib/mp-readline/readline.h"
-#include "lib/utils/pyexec.h"
+#include "shared/readline/readline.h"
+#include "shared/runtime/pyexec.h"
 #include "gccollect.h"
 #include "user_interface.h"
 
diff --git a/ports/esp8266/modesp.c b/ports/esp8266/modesp.c
index 022447313..eb79d20bc 100644
--- a/ports/esp8266/modesp.c
+++ b/ports/esp8266/modesp.c
@@ -36,7 +36,6 @@
 #include "user_interface.h"
 #include "mem.h"
 #include "ets_alt_task.h"
-#include "espneopixel.h"
 #include "espapa102.h"
 #include "modmachine.h"
 
@@ -199,16 +198,6 @@ STATIC mp_obj_t esp_check_fw(void) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(esp_check_fw_obj, esp_check_fw);
 
-
-STATIC mp_obj_t esp_neopixel_write_(mp_obj_t pin, mp_obj_t buf, mp_obj_t is800k) {
-    mp_buffer_info_t bufinfo;
-    mp_get_buffer_raise(buf, &bufinfo, MP_BUFFER_READ);
-    esp_neopixel_write(mp_obj_get_pin_obj(pin)->phys_port,
-        (uint8_t *)bufinfo.buf, bufinfo.len, mp_obj_is_true(is800k));
-    return mp_const_none;
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_3(esp_neopixel_write_obj, esp_neopixel_write_);
-
 #if MICROPY_ESP8266_APA102
 STATIC mp_obj_t esp_apa102_write_(mp_obj_t clockPin, mp_obj_t dataPin, mp_obj_t buf) {
     mp_buffer_info_t bufinfo;
@@ -363,9 +352,6 @@ STATIC const mp_rom_map_elem_t esp_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_flash_erase), MP_ROM_PTR(&esp_flash_erase_obj) },
     { MP_ROM_QSTR(MP_QSTR_flash_size), MP_ROM_PTR(&esp_flash_size_obj) },
     { MP_ROM_QSTR(MP_QSTR_flash_user_start), MP_ROM_PTR(&esp_flash_user_start_obj) },
-    #if MICROPY_ESP8266_NEOPIXEL
-    { MP_ROM_QSTR(MP_QSTR_neopixel_write), MP_ROM_PTR(&esp_neopixel_write_obj) },
-    #endif
     #if MICROPY_ESP8266_APA102
     { MP_ROM_QSTR(MP_QSTR_apa102_write), MP_ROM_PTR(&esp_apa102_write_obj) },
     #endif
diff --git a/ports/esp8266/modmachine.c b/ports/esp8266/modmachine.c
index 86c1d728d..6cd458343 100644
--- a/ports/esp8266/modmachine.c
+++ b/ports/esp8266/modmachine.c
@@ -30,11 +30,12 @@
 
 #include "py/obj.h"
 #include "py/runtime.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 
 // This needs to be set before we include the RTOS headers
 #define USE_US_TIMER 1
 
+#include "extmod/machine_bitstream.h"
 #include "extmod/machine_mem.h"
 #include "extmod/machine_signal.h"
 #include "extmod/machine_pulse.h"
@@ -411,6 +412,10 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_disable_irq), MP_ROM_PTR(&machine_disable_irq_obj) },
     { MP_ROM_QSTR(MP_QSTR_enable_irq), MP_ROM_PTR(&machine_enable_irq_obj) },
 
+    #if MICROPY_PY_MACHINE_BITSTREAM
+    { MP_ROM_QSTR(MP_QSTR_bitstream), MP_ROM_PTR(&machine_bitstream_obj) },
+    #endif
+
     { MP_ROM_QSTR(MP_QSTR_time_pulse_us), MP_ROM_PTR(&machine_time_pulse_us_obj) },
 
     { MP_ROM_QSTR(MP_QSTR_RTC), MP_ROM_PTR(&pyb_rtc_type) },
diff --git a/ports/esp8266/modnetwork.c b/ports/esp8266/modnetwork.c
index 8d153acf0..f0cd83aee 100644
--- a/ports/esp8266/modnetwork.c
+++ b/ports/esp8266/modnetwork.c
@@ -31,7 +31,7 @@
 #include "py/objlist.h"
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "queue.h"
 #include "user_interface.h"
 #include "espconn.h"
@@ -233,7 +233,9 @@ STATIC mp_obj_t esp_scan(mp_obj_t self_in) {
     }
     mp_obj_t list = mp_obj_new_list(0, NULL);
     esp_scan_list = &list;
-    wifi_station_scan(NULL, (scan_done_cb_t)esp_scan_cb);
+    struct scan_config config = {0};
+    config.show_hidden = 1;
+    wifi_station_scan(&config, (scan_done_cb_t)esp_scan_cb);
     while (esp_scan_list != NULL) {
         // our esp_scan_cb is called via ets_loop_iter so it's safe to set the
         // esp_scan_list variable to NULL without disabling interrupts
diff --git a/ports/esp8266/modules/neopixel.py b/ports/esp8266/modules/neopixel.py
deleted file mode 100644
index 9dc153372..000000000
--- a/ports/esp8266/modules/neopixel.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# NeoPixel driver for MicroPython on ESP8266
-# MIT license; Copyright (c) 2016 Damien P. George
-
-from esp import neopixel_write
-
-
-class NeoPixel:
-    ORDER = (1, 0, 2, 3)
-
-    def __init__(self, pin, n, bpp=3, timing=1):
-        self.pin = pin
-        self.n = n
-        self.bpp = bpp
-        self.buf = bytearray(n * bpp)
-        self.pin.init(pin.OUT)
-        self.timing = timing
-
-    def __len__(self):
-        return self.n
-
-    def __setitem__(self, index, val):
-        offset = index * self.bpp
-        for i in range(self.bpp):
-            self.buf[offset + self.ORDER[i]] = val[i]
-
-    def __getitem__(self, index):
-        offset = index * self.bpp
-        return tuple(self.buf[offset + self.ORDER[i]] for i in range(self.bpp))
-
-    def fill(self, color):
-        for i in range(self.n):
-            self[i] = color
-
-    def write(self):
-        neopixel_write(self.pin, self.buf, self.timing)
diff --git a/ports/esp8266/modutime.c b/ports/esp8266/modutime.c
index bcfbf7baf..1d4ecc05f 100644
--- a/ports/esp8266/modutime.c
+++ b/ports/esp8266/modutime.c
@@ -32,7 +32,7 @@
 #include "py/runtime.h"
 #include "py/mphal.h"
 #include "py/smallint.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "modmachine.h"
 #include "user_interface.h"
 #include "extmod/utime_mphal.h"
diff --git a/ports/esp8266/mpconfigport.h b/ports/esp8266/mpconfigport.h
index ac47f0aa2..c7e2f4a44 100644
--- a/ports/esp8266/mpconfigport.h
+++ b/ports/esp8266/mpconfigport.h
@@ -79,6 +79,7 @@
 #define MICROPY_PY_LWIP_SOCK_RAW    (1)
 #define MICROPY_PY_MACHINE          (1)
 #define MICROPY_PY_MACHINE_PIN_MAKE_NEW mp_pin_make_new
+#define MICROPY_PY_MACHINE_BITSTREAM (1)
 #define MICROPY_PY_MACHINE_PULSE    (1)
 #define MICROPY_PY_MACHINE_I2C      (1)
 #define MICROPY_PY_MACHINE_SPI      (1)
@@ -102,7 +103,6 @@
 #define MICROPY_FATFS_MAX_SS           (4096)
 #define MICROPY_FATFS_LFN_CODE_PAGE    437 /* 1=SFN/ANSI 437=LFN/U.S.(OEM) */
 #define MICROPY_ESP8266_APA102         (1)
-#define MICROPY_ESP8266_NEOPIXEL       (1)
 
 #define MICROPY_EVENT_POLL_HOOK {ets_event_poll();}
 #define MICROPY_VM_HOOK_COUNT (10)
@@ -186,6 +186,9 @@ extern const struct _mp_obj_module_t mp_module_onewire;
     mp_obj_t pin_irq_handler[16]; \
     byte *uart0_rxbuf; \
 
+// We need an implementation of the log2 function which is not a macro
+#define MP_NEED_LOG2 (1)
+
 // We need to provide a declaration/definition of alloca()
 #include <alloca.h>
 
diff --git a/ports/esp8266/uart.c b/ports/esp8266/uart.c
index 5ac71da07..978a7efc3 100644
--- a/ports/esp8266/uart.c
+++ b/ports/esp8266/uart.c
@@ -285,7 +285,7 @@ void ICACHE_FLASH_ATTR uart0_set_rxbuf(uint8 *buf, int len) {
 // Task-based UART interface
 
 #include "py/obj.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 
 #if MICROPY_REPL_EVENT_DRIVEN
 void ICACHE_FLASH_ATTR uart_task_handler(os_event_t *evt) {
diff --git a/ports/javascript/Makefile b/ports/javascript/Makefile
index 9cc45d3ef..3fac114f5 100644
--- a/ports/javascript/Makefile
+++ b/ports/javascript/Makefile
@@ -24,11 +24,11 @@ CFLAGS += -DMICROPY_QSTR_EXTRA_POOL=mp_qstr_frozen_const_pool
 CFLAGS += -DMICROPY_MODULE_FROZEN_MPY
 endif
 
-SRC_LIB = $(addprefix lib/,\
-	utils/interrupt_char.c \
-	utils/stdout_helpers.c \
-	utils/pyexec.c \
-	mp-readline/readline.c \
+SRC_SHARED = $(addprefix shared/,\
+	runtime/interrupt_char.c \
+	runtime/stdout_helpers.c \
+	runtime/pyexec.c \
+	readline/readline.c \
 	)
 
 SRC_C = \
@@ -39,11 +39,11 @@ SRC_C = \
 SRC_QSTR += $(SRC_C)
 
 OBJ += $(PY_O)
-OBJ += $(addprefix $(BUILD)/, $(SRC_LIB:.c=.o))
+OBJ += $(addprefix $(BUILD)/, $(SRC_SHARED:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 
 JSFLAGS += -s ASYNCIFY
-JSFLAGS += -s EXPORTED_FUNCTIONS="['_mp_js_init', '_mp_js_init_repl', '_mp_js_do_str', '_mp_js_process_char', '_mp_hal_get_interrupt_char', '_mp_sched_keyboard_interrupt']" -s EXTRA_EXPORTED_RUNTIME_METHODS="['ccall', 'cwrap']" -s --memory-init-file 0 --js-library library.js
+JSFLAGS += -s EXPORTED_FUNCTIONS="['_mp_js_init', '_mp_js_init_repl', '_mp_js_do_str', '_mp_js_process_char', '_mp_hal_get_interrupt_char', '_mp_sched_keyboard_interrupt']" -s EXPORTED_RUNTIME_METHODS="['ccall', 'cwrap']" -s --memory-init-file 0 --js-library library.js
 
 all: $(BUILD)/micropython.js
 
diff --git a/ports/javascript/main.c b/ports/javascript/main.c
index c56f1a2cb..7a04b8eea 100644
--- a/ports/javascript/main.c
+++ b/ports/javascript/main.c
@@ -34,7 +34,7 @@
 #include "py/repl.h"
 #include "py/gc.h"
 #include "py/mperrno.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 
 #include "emscripten.h"
 #include "library.h"
diff --git a/ports/javascript/modutime.c b/ports/javascript/modutime.c
index d05d832ab..05ff8b22f 100644
--- a/ports/javascript/modutime.c
+++ b/ports/javascript/modutime.c
@@ -32,7 +32,7 @@
 #include "py/smallint.h"
 #include "py/obj.h"
 #include "py/runtime.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "extmod/utime_mphal.h"
 
 STATIC const mp_rom_map_elem_t time_module_globals_table[] = {
diff --git a/ports/javascript/mphalport.h b/ports/javascript/mphalport.h
index 614ce8526..3e2c439f3 100644
--- a/ports/javascript/mphalport.h
+++ b/ports/javascript/mphalport.h
@@ -25,7 +25,7 @@
  */
 
 #include "py/obj.h"
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 
 #define mp_hal_stdin_rx_chr() (0)
 void mp_hal_stdout_tx_strn(const char *str, size_t len);
diff --git a/ports/mimxrt/Makefile b/ports/mimxrt/Makefile
index fdb1325fd..818a2a3c8 100644
--- a/ports/mimxrt/Makefile
+++ b/ports/mimxrt/Makefile
@@ -123,6 +123,7 @@ SRC_HAL_IMX_C += \
 	$(MCU_DIR)/drivers/fsl_gpio.c \
 	$(MCU_DIR)/drivers/fsl_gpt.c \
 	$(MCU_DIR)/drivers/fsl_common.c \
+	$(MCU_DIR)/drivers/fsl_lpi2c.c \
 	$(MCU_DIR)/drivers/fsl_lpspi.c \
 	$(MCU_DIR)/drivers/fsl_lpspi_edma.c \
 	$(MCU_DIR)/drivers/fsl_lpuart.c \
@@ -132,7 +133,7 @@ SRC_HAL_IMX_C += \
 	$(MCU_DIR)/drivers/fsl_snvs_lp.c \
 	$(MCU_DIR)/drivers/fsl_trng.c \
 
-SRC_C = \
+SRC_C += \
 	main.c \
 	led.c \
 	pin.c \
@@ -142,6 +143,7 @@ SRC_C = \
 	dma_channel.c \
 	$(BOARD_DIR)/flash_config.c \
 	machine_adc.c \
+	machine_i2c.c \
 	machine_led.c \
 	machine_pin.c \
 	machine_rtc.c \
@@ -154,16 +156,15 @@ SRC_C = \
 	modmimxrt.c \
 	moduos.c \
 	mphalport.c \
-	hal/flexspi_nor_flash.c \
-	lib/mp-readline/readline.c \
-	lib/libc/string0.c \
-	lib/timeutils/timeutils.c \
-	lib/utils/gchelper_native.c \
-	lib/utils/mpirq.c \
-	lib/utils/printf.c \
-	lib/utils/pyexec.c \
-	lib/utils/stdout_helpers.c \
-	lib/utils/sys_stdio_mphal.c \
+	shared/libc/printf.c \
+	shared/libc/string0.c \
+	shared/readline/readline.c \
+	shared/runtime/gchelper_native.c \
+	shared/runtime/mpirq.c \
+	shared/runtime/pyexec.c \
+	shared/runtime/stdout_helpers.c \
+	shared/runtime/sys_stdio_mphal.c \
+	shared/timeutils/timeutils.c \
 	drivers/bus/softspi.c \
 	extmod/modonewire.c \
 	$(SRC_TINYUSB_C) \
@@ -264,7 +265,7 @@ endif
 
 SRC_SS = $(MCU_DIR)/gcc/startup_$(MCU_SERIES).S
 
-SRC_S = lib/utils/gchelper_m3.s \
+SRC_S = shared/runtime/gchelper_m3.s \
 
 # List of sources for qstr extraction
 SRC_QSTR += \
@@ -281,8 +282,8 @@ SRC_QSTR += \
 	modmimxrt.c \
 	moduos.c \
 	pin.c \
-	lib/utils/mpirq.c \
-	lib/utils/sys_stdio_mphal.c \
+	shared/runtime/mpirq.c \
+	shared/runtime/sys_stdio_mphal.c \
 	extmod/modonewire.c \
 	$(GEN_PINS_SRC) \
 
diff --git a/ports/mimxrt/boards/MIMXRT1010_EVK/mpconfigboard.h b/ports/mimxrt/boards/MIMXRT1010_EVK/mpconfigboard.h
index 357670626..2cdb433e1 100644
--- a/ports/mimxrt/boards/MIMXRT1010_EVK/mpconfigboard.h
+++ b/ports/mimxrt/boards/MIMXRT1010_EVK/mpconfigboard.h
@@ -8,6 +8,7 @@
 #define MICROPY_HW_LED_ON(pin) (mp_hal_pin_high(pin))
 #define MICROPY_HW_LED_OFF(pin) (mp_hal_pin_low(pin))
 #define BOARD_FLASH_CONFIG_HEADER_H "evkmimxrt1010_flexspi_nor_config.h"
+#define BOARD_FLASH_OPS_HEADER_H "hal/flexspi_nor_flash.h"
 
 #define MICROPY_HW_NUM_PIN_IRQS (2 * 32)
 
@@ -33,3 +34,15 @@
 
 #define DMA_REQ_SRC_RX { 0, kDmaRequestMuxLPSPI1Rx, kDmaRequestMuxLPSPI2Rx }
 #define DMA_REQ_SRC_TX { 0, kDmaRequestMuxLPSPI1Tx, kDmaRequestMuxLPSPI2Tx } 
+
+// Define mapping hardware I2C # to logical I2C #
+// SDA/SCL  HW-I2C    Logical I2C
+// D14/D15  LPI2C1 ->    0
+// D0/D1    LPI2C2 ->    1
+// D6/D7    LPI2C2 ->    1   Alternatively possible GPIO_AD_01, GPIO_AD_02
+
+#define MICROPY_HW_I2C_INDEX   { 1, 2 }
+
+#define IOMUX_TABLE_I2C \
+    { IOMUXC_GPIO_02_LPI2C1_SCL }, { IOMUXC_GPIO_01_LPI2C1_SDA }, \
+    { IOMUXC_GPIO_10_LPI2C2_SCL }, { IOMUXC_GPIO_09_LPI2C2_SDA },
diff --git a/ports/mimxrt/boards/MIMXRT1010_EVK/mpconfigboard.mk b/ports/mimxrt/boards/MIMXRT1010_EVK/mpconfigboard.mk
index ca8efcd5b..ccc8ffeb4 100644
--- a/ports/mimxrt/boards/MIMXRT1010_EVK/mpconfigboard.mk
+++ b/ports/mimxrt/boards/MIMXRT1010_EVK/mpconfigboard.mk
@@ -3,6 +3,9 @@ MCU_VARIANT = MIMXRT1011DAE5A
 
 MICROPY_FLOAT_IMPL = single
 
+SRC_C += \
+	hal/flexspi_nor_flash.c \
+
 JLINK_PATH = /media/RT1010-EVK/
 JLINK_COMMANDER_SCRIPT = $(BUILD)/script.jlink
 
diff --git a/ports/mimxrt/boards/MIMXRT1020_EVK/mpconfigboard.h b/ports/mimxrt/boards/MIMXRT1020_EVK/mpconfigboard.h
index 55254d58f..d2a2cbbdb 100644
--- a/ports/mimxrt/boards/MIMXRT1020_EVK/mpconfigboard.h
+++ b/ports/mimxrt/boards/MIMXRT1020_EVK/mpconfigboard.h
@@ -9,11 +9,13 @@
 #define MICROPY_HW_LED_ON(pin) (mp_hal_pin_low(pin))
 #define MICROPY_HW_LED_OFF(pin) (mp_hal_pin_high(pin))
 #define BOARD_FLASH_CONFIG_HEADER_H "evkmimxrt1020_flexspi_nor_config.h"
+#define BOARD_FLASH_OPS_HEADER_H "hal/flexspi_nor_flash.h"
 
 #define MICROPY_HW_NUM_PIN_IRQS (3 * 32)
 
 // Define mapping logical UART # to hardware UART #
-// D3/D5   LPUART1  Not usable, Since D3 is blocked.
+// RX/TX   HW-UART    Logical UART
+// D3/D5   LPUART1    Not usable, Since D3 is blocked.
 // D0/D1   LPUART2 -> 1
 // D6/D9   LPUART3 -> 2
 // D10/D12 LPUART5 -> 3
@@ -48,3 +50,17 @@
 
 #define DMA_REQ_SRC_TX { 0, kDmaRequestMuxLPSPI1Tx, kDmaRequestMuxLPSPI2Tx, \
                             kDmaRequestMuxLPSPI3Tx, kDmaRequestMuxLPSPI4Tx } 
+
+// Define mapping hardware I2C # to logical I2C #
+// SDA/SCL  HW-I2C    Logical I2C
+// D14/D15  LPI2C4 ->    0
+// A4/A5    LPI2C1 ->    1
+// D0/D1    LPI2C2 ->    2
+
+#define MICROPY_HW_I2C_INDEX   { 4, 1, 2 }
+
+#define IOMUX_TABLE_I2C \
+    { IOMUXC_GPIO_AD_B1_14_LPI2C1_SCL }, { IOMUXC_GPIO_AD_B1_15_LPI2C1_SDA }, \
+    { IOMUXC_GPIO_AD_B1_08_LPI2C2_SCL }, { IOMUXC_GPIO_AD_B1_09_LPI2C2_SDA }, \
+    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_SD_B1_02_LPI2C4_SCL }, { IOMUXC_GPIO_SD_B1_03_LPI2C4_SDA },
diff --git a/ports/mimxrt/boards/MIMXRT1020_EVK/mpconfigboard.mk b/ports/mimxrt/boards/MIMXRT1020_EVK/mpconfigboard.mk
index b0bbd705c..f8f66b0df 100644
--- a/ports/mimxrt/boards/MIMXRT1020_EVK/mpconfigboard.mk
+++ b/ports/mimxrt/boards/MIMXRT1020_EVK/mpconfigboard.mk
@@ -3,6 +3,9 @@ MCU_VARIANT = MIMXRT1021DAG5A
 
 MICROPY_FLOAT_IMPL = double
 
+SRC_C += \
+	hal/flexspi_nor_flash.c \
+
 JLINK_PATH ?= /media/RT1020-EVK/
 JLINK_COMMANDER_SCRIPT = $(BUILD)/script.jlink
 
diff --git a/ports/mimxrt/boards/MIMXRT1050_EVK/mpconfigboard.h b/ports/mimxrt/boards/MIMXRT1050_EVK/mpconfigboard.h
index db08b1064..af0975bc1 100644
--- a/ports/mimxrt/boards/MIMXRT1050_EVK/mpconfigboard.h
+++ b/ports/mimxrt/boards/MIMXRT1050_EVK/mpconfigboard.h
@@ -8,6 +8,7 @@
 #define MICROPY_HW_LED_ON(pin) (mp_hal_pin_low(pin))
 #define MICROPY_HW_LED_OFF(pin) (mp_hal_pin_high(pin))
 #define BOARD_FLASH_CONFIG_HEADER_H "evkmimxrt1050_flexspi_nor_config.h"
+#define BOARD_FLASH_OPS_HEADER_H "hal/flexspi_nor_flash.h"
 
 #define MICROPY_HW_NUM_PIN_IRQS (4 * 32 + 3)
 
@@ -41,3 +42,15 @@
 
 #define DMA_REQ_SRC_TX { 0, kDmaRequestMuxLPSPI1Tx, kDmaRequestMuxLPSPI2Tx, \
                             kDmaRequestMuxLPSPI3Tx, kDmaRequestMuxLPSPI4Tx } 
+
+// Define the mapping hardware I2C # to logical I2C #
+// SDA/SCL  HW-I2C    Logical I2C
+// D14/D15  LPI2C1 ->    0
+// D1/D0    LPI2C3 ->    1
+
+#define MICROPY_HW_I2C_INDEX   { 1, 3 }
+
+#define IOMUX_TABLE_I2C \
+    { IOMUXC_GPIO_AD_B1_00_LPI2C1_SCL }, { IOMUXC_GPIO_AD_B1_01_LPI2C1_SDA }, \
+    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B1_07_LPI2C3_SCL }, { IOMUXC_GPIO_AD_B1_06_LPI2C3_SDA },
diff --git a/ports/mimxrt/boards/MIMXRT1050_EVK/mpconfigboard.mk b/ports/mimxrt/boards/MIMXRT1050_EVK/mpconfigboard.mk
index e338ec6cf..61826b6f6 100644
--- a/ports/mimxrt/boards/MIMXRT1050_EVK/mpconfigboard.mk
+++ b/ports/mimxrt/boards/MIMXRT1050_EVK/mpconfigboard.mk
@@ -3,6 +3,9 @@ MCU_VARIANT = MIMXRT1052DVL6B
 
 MICROPY_FLOAT_IMPL = double
 
+SRC_C += \
+	hal/flexspi_nor_flash.c \
+
 JLINK_PATH ?= /media/RT1050-EVK/
 
 deploy: $(BUILD)/firmware.bin
diff --git a/ports/mimxrt/boards/MIMXRT1050_EVKB/MIMXRT1050_EVKB.ld b/ports/mimxrt/boards/MIMXRT1050_EVKB/MIMXRT1050_EVKB.ld
new file mode 100644
index 000000000..f616178a9
--- /dev/null
+++ b/ports/mimxrt/boards/MIMXRT1050_EVKB/MIMXRT1050_EVKB.ld
@@ -0,0 +1 @@
+flash_size = 64M;
\ No newline at end of file
diff --git a/ports/mimxrt/boards/MIMXRT1050_EVKB/evkbmimxrt1050_flexspi_nor_config.h b/ports/mimxrt/boards/MIMXRT1050_EVKB/evkbmimxrt1050_flexspi_nor_config.h
new file mode 100644
index 000000000..02ac394e9
--- /dev/null
+++ b/ports/mimxrt/boards/MIMXRT1050_EVKB/evkbmimxrt1050_flexspi_nor_config.h
@@ -0,0 +1,263 @@
+/*
+ * Copyright 2018 NXP
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __EVKMIMXRT1050_FLEXSPI_NOR_CONFIG__
+#define __EVKMIMXRT1050_FLEXSPI_NOR_CONFIG__
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "fsl_flexspi.h"
+
+/*! @name Driver version */
+/*@{*/
+/*! @brief XIP_BOARD driver version 2.0.0. */
+#define FSL_XIP_BOARD_DRIVER_VERSION (MAKE_VERSION(2, 0, 0))
+/*@}*/
+
+/* FLEXSPI memory config block related defintions */
+#define FLEXSPI_CFG_BLK_TAG     (0x42464346UL) // ascii "FCFB" Big Endian
+#define FLEXSPI_CFG_BLK_VERSION (0x56010400UL) // V1.4.0
+#define FLEXSPI_CFG_BLK_SIZE    (512)
+
+/* FLEXSPI Feature related definitions */
+#define FLEXSPI_FEATURE_HAS_PARALLEL_MODE 1
+
+/* Lookup table related defintions */
+#define CMD_INDEX_READ        0
+#define CMD_INDEX_READSTATUS  1
+#define CMD_INDEX_WRITEENABLE 2
+#define CMD_INDEX_WRITE       4
+
+#define CMD_LUT_SEQ_IDX_READ        0
+#define CMD_LUT_SEQ_IDX_READSTATUS  1
+#define CMD_LUT_SEQ_IDX_WRITEENABLE 3
+#define CMD_LUT_SEQ_IDX_WRITE       9
+
+#define CMD_SDR        0x01
+#define CMD_DDR        0x21
+#define RADDR_SDR      0x02
+#define RADDR_DDR      0x22
+#define CADDR_SDR      0x03
+#define CADDR_DDR      0x23
+#define MODE1_SDR      0x04
+#define MODE1_DDR      0x24
+#define MODE2_SDR      0x05
+#define MODE2_DDR      0x25
+#define MODE4_SDR      0x06
+#define MODE4_DDR      0x26
+#define MODE8_SDR      0x07
+#define MODE8_DDR      0x27
+#define WRITE_SDR      0x08
+#define WRITE_DDR      0x28
+#define READ_SDR       0x09
+#define READ_DDR       0x29
+#define LEARN_SDR      0x0A
+#define LEARN_DDR      0x2A
+#define DATSZ_SDR      0x0B
+#define DATSZ_DDR      0x2B
+#define DUMMY_SDR      0x0C
+#define DUMMY_DDR      0x2C
+#define DUMMY_RWDS_SDR 0x0D
+#define DUMMY_RWDS_DDR 0x2D
+#define JMP_ON_CS      0x1F
+#define STOP           0
+
+#define FLEXSPI_1PAD 0
+#define FLEXSPI_2PAD 1
+#define FLEXSPI_4PAD 2
+#define FLEXSPI_8PAD 3
+
+#define FLEXSPI_LUT_SEQ(cmd0, pad0, op0, cmd1, pad1, op1)                                                              \
+    (FLEXSPI_LUT_OPERAND0(op0) | FLEXSPI_LUT_NUM_PADS0(pad0) | FLEXSPI_LUT_OPCODE0(cmd0) | FLEXSPI_LUT_OPERAND1(op1) | \
+     FLEXSPI_LUT_NUM_PADS1(pad1) | FLEXSPI_LUT_OPCODE1(cmd1))
+
+//!@brief Definitions for FlexSPI Serial Clock Frequency
+typedef enum _FlexSpiSerialClockFreq
+{
+    kFlexSpiSerialClk_30MHz  = 1,
+    kFlexSpiSerialClk_50MHz  = 2,
+    kFlexSpiSerialClk_60MHz  = 3,
+    kFlexSpiSerialClk_75MHz  = 4,
+    kFlexSpiSerialClk_80MHz  = 5,
+    kFlexSpiSerialClk_100MHz = 6,
+    kFlexSpiSerialClk_133MHz = 7,
+    kFlexSpiSerialClk_166MHz = 8,
+} flexspi_serial_clk_freq_t;
+
+//!@brief FlexSPI clock configuration type
+enum
+{
+    kFlexSpiClk_SDR, //!< Clock configure for SDR mode
+    kFlexSpiClk_DDR, //!< Clock configurat for DDR mode
+};
+
+//!@brief FlexSPI Read Sample Clock Source definition
+typedef enum _FlashReadSampleClkSource
+{
+    kFlexSPIReadSampleClk_LoopbackInternally      = 0,
+    kFlexSPIReadSampleClk_LoopbackFromDqsPad      = 1,
+    kFlexSPIReadSampleClk_LoopbackFromSckPad      = 2,
+    kFlexSPIReadSampleClk_ExternalInputFromDqsPad = 3,
+} flexspi_read_sample_clk_t;
+
+//!@brief Misc feature bit definitions
+enum
+{
+    kFlexSpiMiscOffset_DiffClkEnable            = 0, //!< Bit for Differential clock enable
+    kFlexSpiMiscOffset_Ck2Enable                = 1, //!< Bit for CK2 enable
+    kFlexSpiMiscOffset_ParallelEnable           = 2, //!< Bit for Parallel mode enable
+    kFlexSpiMiscOffset_WordAddressableEnable    = 3, //!< Bit for Word Addressable enable
+    kFlexSpiMiscOffset_SafeConfigFreqEnable     = 4, //!< Bit for Safe Configuration Frequency enable
+    kFlexSpiMiscOffset_PadSettingOverrideEnable = 5, //!< Bit for Pad setting override enable
+    kFlexSpiMiscOffset_DdrModeEnable            = 6, //!< Bit for DDR clock confiuration indication.
+};
+
+//!@brief Flash Type Definition
+enum
+{
+    kFlexSpiDeviceType_SerialNOR    = 1,    //!< Flash devices are Serial NOR
+    kFlexSpiDeviceType_SerialNAND   = 2,    //!< Flash devices are Serial NAND
+    kFlexSpiDeviceType_SerialRAM    = 3,    //!< Flash devices are Serial RAM/HyperFLASH
+    kFlexSpiDeviceType_MCP_NOR_NAND = 0x12, //!< Flash device is MCP device, A1 is Serial NOR, A2 is Serial NAND
+    kFlexSpiDeviceType_MCP_NOR_RAM  = 0x13, //!< Flash deivce is MCP device, A1 is Serial NOR, A2 is Serial RAMs
+};
+
+//!@brief Flash Pad Definitions
+enum
+{
+    kSerialFlash_1Pad  = 1,
+    kSerialFlash_2Pads = 2,
+    kSerialFlash_4Pads = 4,
+    kSerialFlash_8Pads = 8,
+};
+
+//!@brief FlexSPI LUT Sequence structure
+typedef struct _lut_sequence
+{
+    uint8_t seqNum; //!< Sequence Number, valid number: 1-16
+    uint8_t seqId;  //!< Sequence Index, valid number: 0-15
+    uint16_t reserved;
+} flexspi_lut_seq_t;
+
+//!@brief Flash Configuration Command Type
+enum
+{
+    kDeviceConfigCmdType_Generic,    //!< Generic command, for example: configure dummy cycles, drive strength, etc
+    kDeviceConfigCmdType_QuadEnable, //!< Quad Enable command
+    kDeviceConfigCmdType_Spi2Xpi,    //!< Switch from SPI to DPI/QPI/OPI mode
+    kDeviceConfigCmdType_Xpi2Spi,    //!< Switch from DPI/QPI/OPI to SPI mode
+    kDeviceConfigCmdType_Spi2NoCmd,  //!< Switch to 0-4-4/0-8-8 mode
+    kDeviceConfigCmdType_Reset,      //!< Reset device command
+};
+
+//!@brief FlexSPI Memory Configuration Block
+typedef struct _FlexSPIConfig
+{
+    uint32_t tag;               //!< [0x000-0x003] Tag, fixed value 0x42464346UL
+    uint32_t version;           //!< [0x004-0x007] Version,[31:24] -'V', [23:16] - Major, [15:8] - Minor, [7:0] - bugfix
+    uint32_t reserved0;         //!< [0x008-0x00b] Reserved for future use
+    uint8_t readSampleClkSrc;   //!< [0x00c-0x00c] Read Sample Clock Source, valid value: 0/1/3
+    uint8_t csHoldTime;         //!< [0x00d-0x00d] CS hold time, default value: 3
+    uint8_t csSetupTime;        //!< [0x00e-0x00e] CS setup time, default value: 3
+    uint8_t columnAddressWidth; //!< [0x00f-0x00f] Column Address with, for HyperBus protocol, it is fixed to 3, For
+    //! Serial NAND, need to refer to datasheet
+    uint8_t deviceModeCfgEnable; //!< [0x010-0x010] Device Mode Configure enable flag, 1 - Enable, 0 - Disable
+    uint8_t deviceModeType; //!< [0x011-0x011] Specify the configuration command type:Quad Enable, DPI/QPI/OPI switch,
+    //! Generic configuration, etc.
+    uint16_t waitTimeCfgCommands; //!< [0x012-0x013] Wait time for all configuration commands, unit: 100us, Used for
+    //! DPI/QPI/OPI switch or reset command
+    flexspi_lut_seq_t deviceModeSeq; //!< [0x014-0x017] Device mode sequence info, [7:0] - LUT sequence id, [15:8] - LUt
+    //! sequence number, [31:16] Reserved
+    uint32_t deviceModeArg;    //!< [0x018-0x01b] Argument/Parameter for device configuration
+    uint8_t configCmdEnable;   //!< [0x01c-0x01c] Configure command Enable Flag, 1 - Enable, 0 - Disable
+    uint8_t configModeType[3]; //!< [0x01d-0x01f] Configure Mode Type, similar as deviceModeTpe
+    flexspi_lut_seq_t
+        configCmdSeqs[3]; //!< [0x020-0x02b] Sequence info for Device Configuration command, similar as deviceModeSeq
+    uint32_t reserved1;   //!< [0x02c-0x02f] Reserved for future use
+    uint32_t configCmdArgs[3];     //!< [0x030-0x03b] Arguments/Parameters for device Configuration commands
+    uint32_t reserved2;            //!< [0x03c-0x03f] Reserved for future use
+    uint32_t controllerMiscOption; //!< [0x040-0x043] Controller Misc Options, see Misc feature bit definitions for more
+    //! details
+    uint8_t deviceType;    //!< [0x044-0x044] Device Type:  See Flash Type Definition for more details
+    uint8_t sflashPadType; //!< [0x045-0x045] Serial Flash Pad Type: 1 - Single, 2 - Dual, 4 - Quad, 8 - Octal
+    uint8_t serialClkFreq; //!< [0x046-0x046] Serial Flash Frequencey, device specific definitions, See System Boot
+    //! Chapter for more details
+    uint8_t lutCustomSeqEnable; //!< [0x047-0x047] LUT customization Enable, it is required if the program/erase cannot
+    //! be done using 1 LUT sequence, currently, only applicable to HyperFLASH
+    uint32_t reserved3[2];           //!< [0x048-0x04f] Reserved for future use
+    uint32_t sflashA1Size;           //!< [0x050-0x053] Size of Flash connected to A1
+    uint32_t sflashA2Size;           //!< [0x054-0x057] Size of Flash connected to A2
+    uint32_t sflashB1Size;           //!< [0x058-0x05b] Size of Flash connected to B1
+    uint32_t sflashB2Size;           //!< [0x05c-0x05f] Size of Flash connected to B2
+    uint32_t csPadSettingOverride;   //!< [0x060-0x063] CS pad setting override value
+    uint32_t sclkPadSettingOverride; //!< [0x064-0x067] SCK pad setting override value
+    uint32_t dataPadSettingOverride; //!< [0x068-0x06b] data pad setting override value
+    uint32_t dqsPadSettingOverride;  //!< [0x06c-0x06f] DQS pad setting override value
+    uint32_t timeoutInMs;            //!< [0x070-0x073] Timeout threshold for read status command
+    uint32_t commandInterval;        //!< [0x074-0x077] CS deselect interval between two commands
+    uint16_t dataValidTime[2]; //!< [0x078-0x07b] CLK edge to data valid time for PORT A and PORT B, in terms of 0.1ns
+    uint16_t busyOffset;       //!< [0x07c-0x07d] Busy offset, valid value: 0-31
+    uint16_t busyBitPolarity;  //!< [0x07e-0x07f] Busy flag polarity, 0 - busy flag is 1 when flash device is busy, 1 -
+    //! busy flag is 0 when flash device is busy
+    uint32_t lookupTable[64];           //!< [0x080-0x17f] Lookup table holds Flash command sequences
+    flexspi_lut_seq_t lutCustomSeq[12]; //!< [0x180-0x1af] Customizable LUT Sequences
+    uint32_t reserved4[4];              //!< [0x1b0-0x1bf] Reserved for future use
+} flexspi_mem_config_t;
+
+/*  */
+#define NOR_CMD_LUT_SEQ_IDX_READ_NORMAL 0
+#define NOR_CMD_LUT_SEQ_IDX_READSTATUSREG 1
+#define NOR_CMD_LUT_SEQ_IDX_READ_FAST_QUAD 2
+#define NOR_CMD_LUT_SEQ_IDX_WRITEENABLE 3
+#define NOR_CMD_LUT_SEQ_IDX_READSTATUS_XPI 4
+#define NOR_CMD_LUT_SEQ_IDX_ERASESECTOR 5
+#define NOR_CMD_LUT_SEQ_IDX_WRITESTATUSREG 6
+#define NOR_CMD_LUT_SEQ_IDX_PAGEPROGRAM_QUAD 7
+#define NOR_CMD_LUT_SEQ_IDX_READID 8
+#define NOR_CMD_LUT_SEQ_IDX_PAGEPROGRAM 9
+#define NOR_CMD_LUT_SEQ_IDX_ENTERQPI 10
+#define NOR_CMD_LUT_SEQ_IDX_CHIPERASE 11
+#define NOR_CMD_LUT_SEQ_IDX_EXITQPI 12
+
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA    0
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA   1
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS  2
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE 4
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR 6
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM 10
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP   12
+
+/*
+ *  Serial NOR configuration block
+ */
+typedef struct _flexspi_nor_config
+{
+    flexspi_mem_config_t memConfig; //!< Common memory configuration info via FlexSPI
+    uint32_t pageSize;              //!< Page size of Serial NOR
+    uint32_t sectorSize;            //!< Sector size of Serial NOR
+    uint8_t ipcmdSerialClkFreq;     //!< Clock frequency for IP command
+    uint8_t isUniformBlockSize;     //!< Sector/Block size is the same
+    uint8_t reserved0[2];           //!< Reserved for future use
+    uint8_t serialNorType;          //!< Serial NOR Flash type: 0/1/2/3
+    uint8_t needExitNoCmdMode;      //!< Need to exit NoCmd mode before other IP command
+    uint8_t halfClkForNonReadCmd;   //!< Half the Serial Clock for non-read command: true/false
+    uint8_t needRestoreNoCmdMode;   //!< Need to Restore NoCmd mode after IP commmand execution
+    uint32_t blockSize;             //!< Block size
+    uint32_t reserve2[11];          //!< Reserved for future use
+} flexspi_nor_config_t;
+
+#define FLASH_BUSY_STATUS_POL 0
+#define FLASH_BUSY_STATUS_OFFSET 0
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* __EVKMIMXRT1050_FLEXSPI_NOR_CONFIG__ */
diff --git a/ports/mimxrt/boards/MIMXRT1050_EVKB/flash_config.c b/ports/mimxrt/boards/MIMXRT1050_EVKB/flash_config.c
new file mode 100644
index 000000000..e8190bcb6
--- /dev/null
+++ b/ports/mimxrt/boards/MIMXRT1050_EVKB/flash_config.c
@@ -0,0 +1,186 @@
+/*
+ * Copyright 2018 NXP
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "evkbmimxrt1050_flexspi_nor_config.h"
+
+/* Component ID definition, used by tools. */
+#ifndef FSL_COMPONENT_ID
+#define FSL_COMPONENT_ID "platform.drivers.xip_board"
+#endif
+
+/*******************************************************************************
+ * Code
+ ******************************************************************************/
+#if defined(XIP_BOOT_HEADER_ENABLE) && (XIP_BOOT_HEADER_ENABLE == 1)
+#if defined(__CC_ARM) || defined(__ARMCC_VERSION) || defined(__GNUC__)
+__attribute__((section(".boot_hdr.conf")))
+#elif defined(__ICCARM__)
+#pragma location = ".boot_hdr.conf"
+#endif
+
+const flexspi_nor_config_t qspiflash_config = {
+    .memConfig =
+        {
+            .tag                = FLEXSPI_CFG_BLK_TAG,
+            .version            = FLEXSPI_CFG_BLK_VERSION,
+            .readSampleClkSrc   = kFlexSPIReadSampleClk_ExternalInputFromDqsPad,
+            .csHoldTime         = 3u,
+            .csSetupTime        = 3u,
+            .columnAddressWidth = 3u,
+            // Enable DDR mode, Wordaddressable, Safe configuration, Differential clock
+            .controllerMiscOption =
+                (1u << kFlexSpiMiscOffset_DdrModeEnable) | (1u << kFlexSpiMiscOffset_WordAddressableEnable) |
+                (1u << kFlexSpiMiscOffset_SafeConfigFreqEnable) | (1u << kFlexSpiMiscOffset_DiffClkEnable),
+            .sflashPadType = kSerialFlash_8Pads,
+            .serialClkFreq = kFlexSpiSerialClk_133MHz,
+            .sflashA1Size  = 64u * 1024u * 1024u,
+            .dataValidTime = {16u, 16u},
+            .lookupTable =
+                {
+                    /* 0 Read Data */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xA0, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_READ_DDR, kFLEXSPI_8PAD, 0x04),
+
+                    /* 1 Write Data */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_WRITE_DDR, kFLEXSPI_8PAD, 0x02),
+
+                    /* 2 Read Status */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x70), // DATA 0x70
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xA0, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 5] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_DUMMY_RWDS_DDR, kFLEXSPI_8PAD, 0x0B),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_READ_DDR, kFLEXSPI_8PAD, 0x04, kFLEXSPI_Command_STOP, kFLEXSPI_1PAD, 0x0),
+
+                    /* 4 Write Enable */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // DATA 0xAA
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 5] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x02),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 7] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+
+                    /* 6 Erase Sector  */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x80), // DATA 0x80
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 5] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 7] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    // +2
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 8] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 9] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 10] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x02),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 11] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    // +3
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 12] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 13] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 14] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x30, kFLEXSPI_Command_STOP, kFLEXSPI_1PAD, 0x00),
+
+                    /* 10 program page with word program command sequence */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xA0), // DATA 0xA0
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 5] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_WRITE_DDR, kFLEXSPI_8PAD, 0x80),
+
+                    /* 12 Erase chip */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 1] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 3] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x80),
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 5] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 7] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    // +2
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 8] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 9] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 10] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x02),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 11] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    // +3
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 12] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 13] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 14] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 15] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x10),
+                },
+        },
+    .pageSize           = 512u,
+    .sectorSize         = 256u * 1024u,
+    .blockSize          = 256u * 1024u,
+    .isUniformBlockSize = true,
+};
+
+#endif /* XIP_BOOT_HEADER_ENABLE */
diff --git a/ports/mimxrt/boards/MIMXRT1050_EVKB/mpconfigboard.h b/ports/mimxrt/boards/MIMXRT1050_EVKB/mpconfigboard.h
new file mode 100644
index 000000000..518240b03
--- /dev/null
+++ b/ports/mimxrt/boards/MIMXRT1050_EVKB/mpconfigboard.h
@@ -0,0 +1,69 @@
+#define MICROPY_HW_BOARD_NAME "i.MX RT1050 EVKB"
+#define MICROPY_HW_MCU_NAME   "MIMXRT1052DVL6B"
+
+#define BOARD_FLASH_SIZE (64 * 1024 * 1024)
+
+// MIMXRT1050_EVKB has 1 user LED
+#define MICROPY_HW_LED1_PIN (pin_GPIO_AD_B0_09)
+#define MICROPY_HW_LED_ON(pin) (mp_hal_pin_low(pin))
+#define MICROPY_HW_LED_OFF(pin) (mp_hal_pin_high(pin))
+#define BOARD_FLASH_CONFIG_HEADER_H "evkbmimxrt1050_flexspi_nor_config.h"
+#define BOARD_FLASH_OPS_HEADER_H "hal/flexspi_hyper_flash.h"
+
+#define MICROPY_HW_NUM_PIN_IRQS (4 * 32 + 3)
+
+// Define mapping logical UART # to hardware UART #
+// LPUART3 on D0/D1  -> 1
+// LPUART2 on D7/D6  -> 2
+// LPUART6 on D8/D9  -> 3
+// LPUART8 on A1/A0  -> 4
+
+#define MICROPY_HW_UART_NUM     (sizeof(uart_index_table) / sizeof(uart_index_table)[0])
+#define MICROPY_HW_UART_INDEX   { 0, 3, 2, 6, 8 }
+
+#define IOMUX_TABLE_UART \
+    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B1_02_LPUART2_TX }, { IOMUXC_GPIO_AD_B1_03_LPUART2_RX }, \
+    { IOMUXC_GPIO_AD_B1_06_LPUART3_TX }, { IOMUXC_GPIO_AD_B1_07_LPUART3_RX }, \
+    { 0 }, { 0 }, \
+    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B0_02_LPUART6_TX }, { IOMUXC_GPIO_AD_B0_03_LPUART6_RX }, \
+    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B1_10_LPUART8_TX }, { IOMUXC_GPIO_AD_B1_11_LPUART8_RX },
+
+#define MICROPY_HW_SPI_INDEX { 1 }
+
+#define IOMUX_TABLE_SPI \
+    { IOMUXC_GPIO_SD_B0_00_LPSPI1_SCK }, { IOMUXC_GPIO_SD_B0_01_LPSPI1_PCS0 }, \
+    { IOMUXC_GPIO_SD_B0_02_LPSPI1_SDO }, { IOMUXC_GPIO_SD_B0_03_LPSPI1_SDI },
+
+#define DMA_REQ_SRC_RX { 0, kDmaRequestMuxLPSPI1Rx, kDmaRequestMuxLPSPI2Rx, \
+                            kDmaRequestMuxLPSPI3Rx, kDmaRequestMuxLPSPI4Rx }
+
+#define DMA_REQ_SRC_TX { 0, kDmaRequestMuxLPSPI1Tx, kDmaRequestMuxLPSPI2Tx, \
+                            kDmaRequestMuxLPSPI3Tx, kDmaRequestMuxLPSPI4Tx } 
+
+// Define the mapping hardware I2C # to logical I2C #
+// SDA/SCL  HW-I2C    Logical I2C
+// D14/D15  LPI2C1 ->    0
+// D1/D0    LPI2C3 ->    1
+
+#define MICROPY_HW_I2C_INDEX   { 1, 3 }
+
+#define IOMUX_TABLE_I2C \
+    { IOMUXC_GPIO_AD_B1_00_LPI2C1_SCL }, { IOMUXC_GPIO_AD_B1_01_LPI2C1_SDA }, \
+    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B1_07_LPI2C3_SCL }, { IOMUXC_GPIO_AD_B1_06_LPI2C3_SDA },
+
+#define USDHC_DUMMY_PIN NULL , 0
+
+#define MICROPY_USDHC1 \
+    { \
+        .cmd = {GPIO_SD_B0_00_USDHC1_CMD}, \
+        .clk = { GPIO_SD_B0_01_USDHC1_CLK }, \
+        .cd_b = { GPIO_B1_12_USDHC1_CD_B },\
+        .data0 = { GPIO_SD_B0_02_USDHC1_DATA0 },\
+        .data1 = { GPIO_SD_B0_03_USDHC1_DATA1 },\
+        .data2 = { GPIO_SD_B0_04_USDHC1_DATA2 },\
+        .data3 = { GPIO_SD_B0_05_USDHC1_DATA3 },\
+    }
diff --git a/ports/mimxrt/boards/MIMXRT1050_EVKB/mpconfigboard.mk b/ports/mimxrt/boards/MIMXRT1050_EVKB/mpconfigboard.mk
new file mode 100644
index 000000000..c9e32612c
--- /dev/null
+++ b/ports/mimxrt/boards/MIMXRT1050_EVKB/mpconfigboard.mk
@@ -0,0 +1,12 @@
+MCU_SERIES = MIMXRT1052
+MCU_VARIANT = MIMXRT1052DVL6B
+
+MICROPY_FLOAT_IMPL = double
+
+SRC_C += \
+	hal/flexspi_hyper_flash.c \
+
+JLINK_PATH ?= /media/RT1050-EVKB/
+
+deploy: $(BUILD)/firmware.bin
+	cp $< $(JLINK_PATH)
diff --git a/ports/mimxrt/boards/MIMXRT1050_EVKB/pins.csv b/ports/mimxrt/boards/MIMXRT1050_EVKB/pins.csv
new file mode 100644
index 000000000..366a141ff
--- /dev/null
+++ b/ports/mimxrt/boards/MIMXRT1050_EVKB/pins.csv
@@ -0,0 +1,31 @@
+D0,GPIO_AD_B1_07
+D1,GPIO_AD_B1_06
+D2,GPIO_AD_B0_11
+D3,GPIO_AD_B1_08
+D4,GPIO_AD_B0_09
+D5,GPIO_AD_B0_10
+D6,GPIO_AD_B1_02
+D7,GPIO_AD_B1_03
+D8,GPIO_AD_B0_03
+D9,GPIO_AD_B0_02
+D10,GPIO_SD_B0_01
+D11,GPIO_SD_B0_02
+D12,GPIO_SD_B0_03
+D13,GPIO_SD_B0_00
+D14,GPIO_AD_B1_01
+D15,GPIO_AD_B1_00
+A0,GPIO_AD_B1_10
+A1,GPIO_AD_B1_11
+A2,GPIO_AD_B1_04
+A3,GPIO_AD_B1_05
+A4,GPIO_AD_B1_01
+A5,GPIO_AD_B1_00
+RX,GPIO_AD_B1_07
+TX,GPIO_AD_B1_06
+SCL,GPIO_AD_B1_00
+SDA,GPIO_AD_B1_01
+SCK,GPIO_SD_B0_00
+SDI,GPIO_SD_B0_03
+SDO,GPIO_SD_B0_02
+CS,GPIO_SD_B0_01
+LED_GREEN,GPIO_AD_B0_09
diff --git a/ports/mimxrt/boards/MIMXRT1052.ld b/ports/mimxrt/boards/MIMXRT1052.ld
index f78773531..751929794 100644
--- a/ports/mimxrt/boards/MIMXRT1052.ld
+++ b/ports/mimxrt/boards/MIMXRT1052.ld
@@ -8,8 +8,8 @@ ivt_size            = 0x00001000;
 interrupts_start    = 0x60002000;
 interrupts_size     = 0x00000400;
 text_start          = 0x60002400;
-text_size           = ((((text_start) + 1M) + (4k - 1)) & ~(4k - 1)) - (text_start); /* reserve 1M for code but align on 4k boundary */
-vfs_start           = (text_start) + (text_size);
+vfs_start           = 0x60100000;
+text_size           = ((vfs_start) - (text_start));
 vfs_size            = ((flash_end) - (vfs_start));
 itcm_start          = 0x00000000;
 itcm_size           = 0x00020000;
diff --git a/ports/mimxrt/boards/MIMXRT1060_EVK/MIMXRT1060_EVK.ld b/ports/mimxrt/boards/MIMXRT1060_EVK/MIMXRT1060_EVK.ld
index fd1bf32ed..f616178a9 100644
--- a/ports/mimxrt/boards/MIMXRT1060_EVK/MIMXRT1060_EVK.ld
+++ b/ports/mimxrt/boards/MIMXRT1060_EVK/MIMXRT1060_EVK.ld
@@ -1 +1 @@
-flash_size = 8M;
\ No newline at end of file
+flash_size = 64M;
\ No newline at end of file
diff --git a/ports/mimxrt/boards/MIMXRT1060_EVK/evkmimxrt1060_flexspi_nor_config.h b/ports/mimxrt/boards/MIMXRT1060_EVK/evkmimxrt1060_flexspi_nor_config.h
index 03bdac1f1..cff520e0e 100644
--- a/ports/mimxrt/boards/MIMXRT1060_EVK/evkmimxrt1060_flexspi_nor_config.h
+++ b/ports/mimxrt/boards/MIMXRT1060_EVK/evkmimxrt1060_flexspi_nor_config.h
@@ -10,7 +10,7 @@
 
 #include <stdint.h>
 #include <stdbool.h>
-#include "fsl_common.h"
+#include "fsl_flexspi.h"
 
 /*! @name Driver version */
 /*@{*/
@@ -224,6 +224,14 @@ typedef struct _FlexSPIConfig
 #define NOR_CMD_LUT_SEQ_IDX_CHIPERASE 11
 #define NOR_CMD_LUT_SEQ_IDX_EXITQPI 12
 
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA    0
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA   1
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS  2
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE 4
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR 6
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM 10
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP   12
+
 /*
  *  Serial NOR configuration block
  */
diff --git a/ports/mimxrt/boards/MIMXRT1060_EVK/flash_config.c b/ports/mimxrt/boards/MIMXRT1060_EVK/flash_config.c
index 3fa584b73..e28f58154 100644
--- a/ports/mimxrt/boards/MIMXRT1060_EVK/flash_config.c
+++ b/ports/mimxrt/boards/MIMXRT1060_EVK/flash_config.c
@@ -25,98 +25,162 @@ __attribute__((section(".boot_hdr.conf")))
 const flexspi_nor_config_t qspiflash_config = {
     .memConfig =
         {
-            .tag              = FLEXSPI_CFG_BLK_TAG,
-            .version          = FLEXSPI_CFG_BLK_VERSION,
-            .readSampleClkSrc = kFlexSPIReadSampleClk_LoopbackFromDqsPad,
-            .csHoldTime       = 3u,
-            .csSetupTime      = 3u,
-            .sflashPadType    = kSerialFlash_4Pads,
-            .serialClkFreq    = kFlexSpiSerialClk_100MHz,
-            .sflashA1Size     = 8u * 1024u * 1024u,
+            .tag                = FLEXSPI_CFG_BLK_TAG,
+            .version            = FLEXSPI_CFG_BLK_VERSION,
+            .readSampleClkSrc   = kFlexSPIReadSampleClk_ExternalInputFromDqsPad,
+            .csHoldTime         = 3u,
+            .csSetupTime        = 3u,
+            .columnAddressWidth = 3u,
+            // Enable DDR mode, Wordaddressable, Safe configuration, Differential clock
+            .controllerMiscOption =
+                (1u << kFlexSpiMiscOffset_DdrModeEnable) | (1u << kFlexSpiMiscOffset_WordAddressableEnable) |
+                (1u << kFlexSpiMiscOffset_SafeConfigFreqEnable) | (1u << kFlexSpiMiscOffset_DiffClkEnable),
+            .sflashPadType = kSerialFlash_8Pads,
+            .serialClkFreq = kFlexSpiSerialClk_133MHz,
+            .sflashA1Size  = 64u * 1024u * 1024u,
+            .dataValidTime = {16u, 16u},
             .lookupTable =
                 {
-                    // 0 Read LUTs 0 -> 0
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0xEB, RADDR_SDR, FLEXSPI_4PAD, 0x18),
-                    FLEXSPI_LUT_SEQ(DUMMY_SDR, FLEXSPI_4PAD, 0x06, READ_SDR, FLEXSPI_4PAD, 0x04),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 0 Read Data */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xA0, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_READ_DDR, kFLEXSPI_8PAD, 0x04),
 
-                    // 1 Read status register -> 1
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x05, READ_SDR, FLEXSPI_1PAD, 0x01),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 1 Write Data */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_WRITE_DDR, kFLEXSPI_8PAD, 0x02),
 
-                    // 2 Fast read quad mode - SDR
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x6B, RADDR_SDR, FLEXSPI_1PAD, 0x18),
-                    FLEXSPI_LUT_SEQ(DUMMY_SDR, FLEXSPI_4PAD, 0x08, READ_SDR, FLEXSPI_4PAD, 0x04),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 2 Read Status */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x70), // DATA 0x70
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xA0, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 5] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_DUMMY_RWDS_DDR, kFLEXSPI_8PAD, 0x0B),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_READ_DDR, kFLEXSPI_8PAD, 0x04, kFLEXSPI_Command_STOP, kFLEXSPI_1PAD, 0x0),
 
-                    // 3 Write Enable -> 3
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x06, STOP, FLEXSPI_1PAD, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 4 Write Enable */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // DATA 0xAA
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 5] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x02),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 7] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
 
-                    // 4 Read extend parameters
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x81, READ_SDR, FLEXSPI_1PAD, 0x04),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 6 Erase Sector  */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x80), // DATA 0x80
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 5] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 7] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    // +2
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 8] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 9] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 10] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x02),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 11] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    // +3
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 12] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 13] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 14] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x30, kFLEXSPI_Command_STOP, kFLEXSPI_1PAD, 0x00),
 
-                    // 5 Erase Sector -> 5
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x20, RADDR_SDR, FLEXSPI_1PAD, 24),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 10 program page with word program command sequence */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xA0), // DATA 0xA0
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 5] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_WRITE_DDR, kFLEXSPI_8PAD, 0x80),
 
-                    // 6 Write Status Reg
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x01, WRITE_SDR, FLEXSPI_1PAD, 0x04),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 7 Page Program - quad mode (-> 9)
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x32, RADDR_SDR, FLEXSPI_1PAD, 0x18),
-                    FLEXSPI_LUT_SEQ(WRITE_SDR, FLEXSPI_4PAD, 0x04, STOP, FLEXSPI_1PAD, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 8 Read ID
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x90, DUMMY_SDR, FLEXSPI_1PAD, 24),
-                    FLEXSPI_LUT_SEQ(READ_SDR, FLEXSPI_1PAD, 0x00, 0, 0, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 9 Page Program - single mode -> 9
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x02, RADDR_SDR, FLEXSPI_1PAD, 24),
-                    FLEXSPI_LUT_SEQ(WRITE_SDR, FLEXSPI_1PAD, 0, 0, 0, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 10 Enter QPI mode
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x35, STOP, FLEXSPI_1PAD, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 11 Erase Chip
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x60, STOP, FLEXSPI_1PAD, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 12 Exit QPI mode
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_4PAD, 0xF5, STOP, FLEXSPI_1PAD, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 12 Erase chip */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 1] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 3] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x80),
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 5] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 7] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    // +2
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 8] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 9] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 10] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x02),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 11] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    // +3
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 12] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 13] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 14] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 15] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x10),
                 },
         },
-    .pageSize           = 256u,
-    .sectorSize         = 4u * 1024u,
-    .blockSize          = 64u * 1024u,
-    .isUniformBlockSize = false,
+    .pageSize           = 512u,
+    .sectorSize         = 256u * 1024u,
+    .blockSize          = 256u * 1024u,
+    .isUniformBlockSize = true,
 };
+
 #endif /* XIP_BOOT_HEADER_ENABLE */
diff --git a/ports/mimxrt/boards/MIMXRT1060_EVK/mpconfigboard.h b/ports/mimxrt/boards/MIMXRT1060_EVK/mpconfigboard.h
index 451d53daf..c207da832 100644
--- a/ports/mimxrt/boards/MIMXRT1060_EVK/mpconfigboard.h
+++ b/ports/mimxrt/boards/MIMXRT1060_EVK/mpconfigboard.h
@@ -8,6 +8,7 @@
 #define MICROPY_HW_LED_ON(pin) (mp_hal_pin_low(pin))
 #define MICROPY_HW_LED_OFF(pin) (mp_hal_pin_high(pin))
 #define BOARD_FLASH_CONFIG_HEADER_H "evkmimxrt1060_flexspi_nor_config.h"
+#define BOARD_FLASH_OPS_HEADER_H "hal/flexspi_hyper_flash.h"
 
 #define MICROPY_HW_NUM_PIN_IRQS (4 * 32 + 3)
 
@@ -41,3 +42,15 @@
 
 #define DMA_REQ_SRC_TX { 0, kDmaRequestMuxLPSPI1Tx, kDmaRequestMuxLPSPI2Tx, \
                             kDmaRequestMuxLPSPI3Tx, kDmaRequestMuxLPSPI4Tx } 
+
+// Define the mapping hardware I2C # to logical I2C #
+// SDA/SCL  HW-I2C    Logical I2C
+// D14/D15  LPI2C1 ->    0
+// D1/D0    LPI2C3 ->    1
+
+#define MICROPY_HW_I2C_INDEX   { 1, 3 }
+
+#define IOMUX_TABLE_I2C \
+    { IOMUXC_GPIO_AD_B1_00_LPI2C1_SCL }, { IOMUXC_GPIO_AD_B1_01_LPI2C1_SDA }, \
+    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B1_07_LPI2C3_SCL }, { IOMUXC_GPIO_AD_B1_06_LPI2C3_SDA },
diff --git a/ports/mimxrt/boards/MIMXRT1060_EVK/mpconfigboard.mk b/ports/mimxrt/boards/MIMXRT1060_EVK/mpconfigboard.mk
index b7ea5fcbe..f5eaf3eab 100644
--- a/ports/mimxrt/boards/MIMXRT1060_EVK/mpconfigboard.mk
+++ b/ports/mimxrt/boards/MIMXRT1060_EVK/mpconfigboard.mk
@@ -3,6 +3,9 @@ MCU_VARIANT = MIMXRT1062DVJ6A
 
 MICROPY_FLOAT_IMPL = double
 
+SRC_C += \
+	hal/flexspi_hyper_flash.c \
+
 JLINK_PATH ?= /media/RT1060-EVK/
 JLINK_COMMANDER_SCRIPT = $(BUILD)/script.jlink
 
diff --git a/ports/mimxrt/boards/MIMXRT1064.ld b/ports/mimxrt/boards/MIMXRT1064.ld
index 236d98429..820393001 100644
--- a/ports/mimxrt/boards/MIMXRT1064.ld
+++ b/ports/mimxrt/boards/MIMXRT1064.ld
@@ -8,8 +8,8 @@ ivt_size            = 0x00001000;
 interrupts_start    = 0x60002000;
 interrupts_size     = 0x00000400;
 text_start          = 0x60002400;
-text_size           = ((((text_start) + 1M) + (4k - 1)) & ~(4k - 1)) - (text_start); /* reserve 1M for code but align on 4k boundary */
-vfs_start           = (text_start) + (text_size);
+vfs_start           = 0x60100000;
+text_size           = ((vfs_start) - (text_start));
 vfs_size            = ((flash_end) - (vfs_start));
 itcm_start          = 0x00000000;
 itcm_size           = 0x00020000;
@@ -25,4 +25,4 @@ _sstack = __StackLimit;
 
 /* Use second OCRAM bank for GC heap. */
 _gc_heap_start = ORIGIN(m_ocrm);
-_gc_heap_end = ORIGIN(m_ocrm) + LENGTH(m_ocrm);
\ No newline at end of file
+_gc_heap_end = ORIGIN(m_ocrm) + LENGTH(m_ocrm);
diff --git a/ports/mimxrt/boards/MIMXRT1064_EVK/MIMXRT1064_EVK.ld b/ports/mimxrt/boards/MIMXRT1064_EVK/MIMXRT1064_EVK.ld
index fd1bf32ed..f616178a9 100644
--- a/ports/mimxrt/boards/MIMXRT1064_EVK/MIMXRT1064_EVK.ld
+++ b/ports/mimxrt/boards/MIMXRT1064_EVK/MIMXRT1064_EVK.ld
@@ -1 +1 @@
-flash_size = 8M;
\ No newline at end of file
+flash_size = 64M;
\ No newline at end of file
diff --git a/ports/mimxrt/boards/MIMXRT1064_EVK/evkmimxrt1064_flexspi_nor_config.h b/ports/mimxrt/boards/MIMXRT1064_EVK/evkmimxrt1064_flexspi_nor_config.h
index 3c433f3be..7560f2483 100644
--- a/ports/mimxrt/boards/MIMXRT1064_EVK/evkmimxrt1064_flexspi_nor_config.h
+++ b/ports/mimxrt/boards/MIMXRT1064_EVK/evkmimxrt1064_flexspi_nor_config.h
@@ -10,7 +10,7 @@
 
 #include <stdint.h>
 #include <stdbool.h>
-#include "fsl_common.h"
+#include "fsl_flexspi.h"
 
 /*! @name Driver version */
 /*@{*/
@@ -19,9 +19,9 @@
 /*@}*/
 
 /* FLEXSPI memory config block related defintions */
-#define FLEXSPI_CFG_BLK_TAG (0x42464346UL)     // ascii "FCFB" Big Endian
+#define FLEXSPI_CFG_BLK_TAG     (0x42464346UL) // ascii "FCFB" Big Endian
 #define FLEXSPI_CFG_BLK_VERSION (0x56010400UL) // V1.4.0
-#define FLEXSPI_CFG_BLK_SIZE (512)
+#define FLEXSPI_CFG_BLK_SIZE    (512)
 
 /* FLEXSPI Feature related definitions */
 #define FLEXSPI_FEATURE_HAS_PARALLEL_MODE 1
@@ -223,6 +223,15 @@ typedef struct _FlexSPIConfig
 #define NOR_CMD_LUT_SEQ_IDX_ENTERQPI 10
 #define NOR_CMD_LUT_SEQ_IDX_CHIPERASE 11
 #define NOR_CMD_LUT_SEQ_IDX_EXITQPI 12
+
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA    0
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA   1
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS  2
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE 4
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR 6
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM 10
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP   12
+
 /*
  *  Serial NOR configuration block
  */
diff --git a/ports/mimxrt/boards/MIMXRT1064_EVK/flash_config.c b/ports/mimxrt/boards/MIMXRT1064_EVK/flash_config.c
index 9338c6948..f308b7f8a 100644
--- a/ports/mimxrt/boards/MIMXRT1064_EVK/flash_config.c
+++ b/ports/mimxrt/boards/MIMXRT1064_EVK/flash_config.c
@@ -25,99 +25,162 @@ __attribute__((section(".boot_hdr.conf")))
 const flexspi_nor_config_t qspiflash_config = {
     .memConfig =
         {
-            .tag              = FLEXSPI_CFG_BLK_TAG,
-            .version          = FLEXSPI_CFG_BLK_VERSION,
-            .readSampleClkSrc = kFlexSPIReadSampleClk_LoopbackFromDqsPad,
-            .csHoldTime       = 3u,
-            .csSetupTime      = 3u,
-            // Enable DDR mode, Wordaddassable, Safe configuration, Differential clock
-            .sflashPadType = kSerialFlash_4Pads,
-            .serialClkFreq = kFlexSpiSerialClk_100MHz,
-            .sflashA1Size  = 8u * 1024u * 1024u,
+            .tag                = FLEXSPI_CFG_BLK_TAG,
+            .version            = FLEXSPI_CFG_BLK_VERSION,
+            .readSampleClkSrc   = kFlexSPIReadSampleClk_ExternalInputFromDqsPad,
+            .csHoldTime         = 3u,
+            .csSetupTime        = 3u,
+            .columnAddressWidth = 3u,
+            // Enable DDR mode, Wordaddressable, Safe configuration, Differential clock
+            .controllerMiscOption =
+                (1u << kFlexSpiMiscOffset_DdrModeEnable) | (1u << kFlexSpiMiscOffset_WordAddressableEnable) |
+                (1u << kFlexSpiMiscOffset_SafeConfigFreqEnable) | (1u << kFlexSpiMiscOffset_DiffClkEnable),
+            .sflashPadType = kSerialFlash_8Pads,
+            .serialClkFreq = kFlexSpiSerialClk_133MHz,
+            .sflashA1Size  = 64u * 1024u * 1024u,
+            .dataValidTime = {16u, 16u},
             .lookupTable =
                 {
-                    // 0 Read LUTs 0 -> 0
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0xEB, RADDR_SDR, FLEXSPI_4PAD, 0x18),
-                    FLEXSPI_LUT_SEQ(DUMMY_SDR, FLEXSPI_4PAD, 0x06, READ_SDR, FLEXSPI_4PAD, 0x04),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 0 Read Data */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xA0, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_READ_DDR, kFLEXSPI_8PAD, 0x04),
 
-                    // 1 Read status register -> 1
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x05, READ_SDR, FLEXSPI_1PAD, 0x01),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 1 Write Data */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_WRITE_DDR, kFLEXSPI_8PAD, 0x02),
 
-                    // 2 Fast read quad mode - SDR
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x6B, RADDR_SDR, FLEXSPI_1PAD, 0x18),
-                    FLEXSPI_LUT_SEQ(DUMMY_SDR, FLEXSPI_4PAD, 0x08, READ_SDR, FLEXSPI_4PAD, 0x04),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 2 Read Status */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x70), // DATA 0x70
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xA0, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 5] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_DUMMY_RWDS_DDR, kFLEXSPI_8PAD, 0x0B),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_READ_DDR, kFLEXSPI_8PAD, 0x04, kFLEXSPI_Command_STOP, kFLEXSPI_1PAD, 0x0),
 
-                    // 3 Write Enable -> 3
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x06, STOP, FLEXSPI_1PAD, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 4 Write Enable */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // DATA 0xAA
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 5] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x02),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE + 7] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
 
-                    // 4 Read extend parameters
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x81, READ_SDR, FLEXSPI_1PAD, 0x04),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 6 Erase Sector  */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x80), // DATA 0x80
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 5] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 7] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    // +2
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 8] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 9] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 10] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x02),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 11] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    // +3
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 12] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 13] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR + 14] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x30, kFLEXSPI_Command_STOP, kFLEXSPI_1PAD, 0x00),
 
-                    // 5 Erase Sector -> 5
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x20, RADDR_SDR, FLEXSPI_1PAD, 24),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 10 program page with word program command sequence */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 1] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA), // ADDR 0x555
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 3] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xA0), // DATA 0xA0
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x20, kFLEXSPI_Command_RADDR_DDR, kFLEXSPI_8PAD, 0x18),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM + 5] = FLEXSPI_LUT_SEQ(
+                        kFLEXSPI_Command_CADDR_DDR, kFLEXSPI_8PAD, 0x10, kFLEXSPI_Command_WRITE_DDR, kFLEXSPI_8PAD, 0x80),
 
-                    // 6 Write Status Reg
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x01, WRITE_SDR, FLEXSPI_1PAD, 0x04),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 7 Page Program - quad mode (-> 9)
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x32, RADDR_SDR, FLEXSPI_1PAD, 0x18),
-                    FLEXSPI_LUT_SEQ(WRITE_SDR, FLEXSPI_4PAD, 0x04, STOP, FLEXSPI_1PAD, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 8 Read ID
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x90, DUMMY_SDR, FLEXSPI_1PAD, 24),
-                    FLEXSPI_LUT_SEQ(READ_SDR, FLEXSPI_1PAD, 0x00, 0, 0, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 9 Page Program - single mode -> 9
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x02, RADDR_SDR, FLEXSPI_1PAD, 24),
-                    FLEXSPI_LUT_SEQ(WRITE_SDR, FLEXSPI_1PAD, 0, 0, 0, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 10 Enter QPI mode
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x35, STOP, FLEXSPI_1PAD, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 11 Erase Chip
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_1PAD, 0x60, STOP, FLEXSPI_1PAD, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-
-                    // 12 Exit QPI mode
-                    FLEXSPI_LUT_SEQ(CMD_SDR, FLEXSPI_4PAD, 0xF5, STOP, FLEXSPI_1PAD, 0),
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
-                    FLEXSPI_LUT_SEQ(0, 0, 0, 0, 0, 0), // Filler
+                    /* 12 Erase chip */
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 1] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 2] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 3] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x80),
+                    // +1
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 4] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 5] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 6] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 7] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    // +2
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 8] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 9] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 10] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x02),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 11] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x55),
+                    // +3
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 12] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 13] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0xAA),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 14] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x05),
+                    [4 * HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP + 15] =
+                        FLEXSPI_LUT_SEQ(kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x00, kFLEXSPI_Command_DDR, kFLEXSPI_8PAD, 0x10),
                 },
         },
-    .pageSize           = 256u,
-    .sectorSize         = 4u * 1024u,
+    .pageSize           = 512u,
+    .sectorSize         = 256u * 1024u,
     .blockSize          = 256u * 1024u,
-    .isUniformBlockSize = false,
+    .isUniformBlockSize = true,
 };
+
 #endif /* XIP_BOOT_HEADER_ENABLE */
diff --git a/ports/mimxrt/boards/MIMXRT1064_EVK/mpconfigboard.h b/ports/mimxrt/boards/MIMXRT1064_EVK/mpconfigboard.h
index e300efef3..59f28b0e2 100644
--- a/ports/mimxrt/boards/MIMXRT1064_EVK/mpconfigboard.h
+++ b/ports/mimxrt/boards/MIMXRT1064_EVK/mpconfigboard.h
@@ -6,6 +6,7 @@
 #define MICROPY_HW_LED_ON(pin) (mp_hal_pin_low(pin))
 #define MICROPY_HW_LED_OFF(pin) (mp_hal_pin_high(pin))
 #define BOARD_FLASH_CONFIG_HEADER_H "evkmimxrt1064_flexspi_nor_config.h"
+#define BOARD_FLASH_OPS_HEADER_H "hal/flexspi_hyper_flash.h"
 
 #define MICROPY_HW_NUM_PIN_IRQS (4 * 32 + 3)
 
@@ -39,3 +40,15 @@
 
 #define DMA_REQ_SRC_TX { 0, kDmaRequestMuxLPSPI1Tx, kDmaRequestMuxLPSPI2Tx, \
                             kDmaRequestMuxLPSPI3Tx, kDmaRequestMuxLPSPI4Tx } 
+
+// Define the mapping hardware I2C # to logical I2C #
+// SDA/SCL  HW-I2C    Logical I2C
+// D14/D15  LPI2C1 ->    0
+// D1/D0    LPI2C3 ->    1
+
+#define MICROPY_HW_I2C_INDEX   { 1, 3 }
+
+#define IOMUX_TABLE_I2C \
+    { IOMUXC_GPIO_AD_B1_00_LPI2C1_SCL }, { IOMUXC_GPIO_AD_B1_01_LPI2C1_SDA }, \
+    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B1_07_LPI2C3_SCL }, { IOMUXC_GPIO_AD_B1_06_LPI2C3_SDA },
diff --git a/ports/mimxrt/boards/MIMXRT1064_EVK/mpconfigboard.mk b/ports/mimxrt/boards/MIMXRT1064_EVK/mpconfigboard.mk
index bd4c49641..444fe9967 100644
--- a/ports/mimxrt/boards/MIMXRT1064_EVK/mpconfigboard.mk
+++ b/ports/mimxrt/boards/MIMXRT1064_EVK/mpconfigboard.mk
@@ -3,6 +3,9 @@ MCU_VARIANT = MIMXRT1064DVL6A
 
 MICROPY_FLOAT_IMPL = double
 
+SRC_C += \
+	hal/flexspi_hyper_flash.c \
+
 JLINK_PATH ?= /media/RT1064-EVK/
 
 CFLAGS += -DBOARD_FLASH_SIZE=0x400000
diff --git a/ports/mimxrt/boards/TEENSY40/mpconfigboard.h b/ports/mimxrt/boards/TEENSY40/mpconfigboard.h
index 8b38d047f..aacee4623 100644
--- a/ports/mimxrt/boards/TEENSY40/mpconfigboard.h
+++ b/ports/mimxrt/boards/TEENSY40/mpconfigboard.h
@@ -8,6 +8,7 @@
 #define MICROPY_HW_LED_ON(pin) (mp_hal_pin_high(pin))
 #define MICROPY_HW_LED_OFF(pin) (mp_hal_pin_low(pin))
 #define BOARD_FLASH_CONFIG_HEADER_H "teensy40_flexspi_nor_config.h"
+#define BOARD_FLASH_OPS_HEADER_H "hal/flexspi_nor_flash.h"
 
 #define MICROPY_HW_NUM_PIN_IRQS (4 * 32 + 3)
 
@@ -42,3 +43,17 @@
 
 #define DMA_REQ_SRC_TX { 0, kDmaRequestMuxLPSPI1Tx, kDmaRequestMuxLPSPI2Tx, \
                             kDmaRequestMuxLPSPI3Tx, kDmaRequestMuxLPSPI4Tx } 
+
+// Define mapping hardware I2C # to logical I2C #
+// SDA/SCL  HW-I2C    Logical I2C
+// 17/16    LPI2C3 ->    0
+// 18/19    LPI2C1 ->    1
+// 25/24    LPI2C4 ->    2
+
+#define MICROPY_HW_I2C_INDEX   { 1, 3, 4 }
+
+#define IOMUX_TABLE_I2C \
+    { IOMUXC_GPIO_AD_B1_00_LPI2C1_SCL }, { IOMUXC_GPIO_AD_B1_01_LPI2C1_SDA }, \
+    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B1_07_LPI2C3_SCL }, { IOMUXC_GPIO_AD_B1_06_LPI2C3_SDA }, \
+    { IOMUXC_GPIO_AD_B0_12_LPI2C4_SCL }, { IOMUXC_GPIO_AD_B0_13_LPI2C4_SDA },
diff --git a/ports/mimxrt/boards/TEENSY40/mpconfigboard.mk b/ports/mimxrt/boards/TEENSY40/mpconfigboard.mk
index beab16c08..a15dd7812 100644
--- a/ports/mimxrt/boards/TEENSY40/mpconfigboard.mk
+++ b/ports/mimxrt/boards/TEENSY40/mpconfigboard.mk
@@ -3,5 +3,8 @@ MCU_VARIANT = MIMXRT1062DVJ6A
 
 MICROPY_FLOAT_IMPL = double
 
+SRC_C += \
+	hal/flexspi_nor_flash.c \
+
 deploy: $(BUILD)/firmware.hex
 	teensy_loader_cli --mcu=imxrt1062 -v -w $<
diff --git a/ports/mimxrt/boards/TEENSY41/mpconfigboard.h b/ports/mimxrt/boards/TEENSY41/mpconfigboard.h
index 455bf8d69..a72bd127b 100644
--- a/ports/mimxrt/boards/TEENSY41/mpconfigboard.h
+++ b/ports/mimxrt/boards/TEENSY41/mpconfigboard.h
@@ -8,6 +8,7 @@
 #define MICROPY_HW_LED_ON(pin) (mp_hal_pin_high(pin))
 #define MICROPY_HW_LED_OFF(pin) (mp_hal_pin_low(pin))
 #define BOARD_FLASH_CONFIG_HEADER_H "teensy41_flexspi_nor_config.h"
+#define BOARD_FLASH_OPS_HEADER_H "hal/flexspi_nor_flash.h"
 
 #define MICROPY_HW_NUM_PIN_IRQS (4 * 32 + 3)
 
@@ -42,3 +43,17 @@
 
 #define DMA_REQ_SRC_TX { 0, kDmaRequestMuxLPSPI1Tx, kDmaRequestMuxLPSPI2Tx, \
                             kDmaRequestMuxLPSPI3Tx, kDmaRequestMuxLPSPI4Tx } 
+
+// Define mapping hardware I2C # to logical I2C #
+// SDA/SCL  HW-I2C    Logical I2C
+// 17/16    LPI2C3 ->    0
+// 18/19    LPI2C1 ->    1
+// 25/24    LPI2C4 ->    2
+
+#define MICROPY_HW_I2C_INDEX   { 1, 3, 4 }
+
+#define IOMUX_TABLE_I2C \
+    { IOMUXC_GPIO_AD_B1_00_LPI2C1_SCL }, { IOMUXC_GPIO_AD_B1_01_LPI2C1_SDA }, \
+    { 0 }, { 0 }, \
+    { IOMUXC_GPIO_AD_B1_07_LPI2C3_SCL }, { IOMUXC_GPIO_AD_B1_06_LPI2C3_SDA }, \
+    { IOMUXC_GPIO_AD_B0_12_LPI2C4_SCL }, { IOMUXC_GPIO_AD_B0_13_LPI2C4_SDA },
diff --git a/ports/mimxrt/boards/TEENSY41/mpconfigboard.mk b/ports/mimxrt/boards/TEENSY41/mpconfigboard.mk
index beab16c08..a15dd7812 100755
--- a/ports/mimxrt/boards/TEENSY41/mpconfigboard.mk
+++ b/ports/mimxrt/boards/TEENSY41/mpconfigboard.mk
@@ -3,5 +3,8 @@ MCU_VARIANT = MIMXRT1062DVJ6A
 
 MICROPY_FLOAT_IMPL = double
 
+SRC_C += \
+	hal/flexspi_nor_flash.c \
+
 deploy: $(BUILD)/firmware.hex
 	teensy_loader_cli --mcu=imxrt1062 -v -w $<
diff --git a/ports/mimxrt/boards/common.ld b/ports/mimxrt/boards/common.ld
index e5d91f119..6f45da24d 100644
--- a/ports/mimxrt/boards/common.ld
+++ b/ports/mimxrt/boards/common.ld
@@ -178,12 +178,14 @@ SECTIONS
     . = ALIGN(4);
     __DATA_RAM = .;
     __data_start__ = .;      /* create a global symbol at data start */
+    __data_section_table = .;
     *(m_usb_dma_init_data)
     *(.data)                 /* .data sections */
     *(.data*)                /* .data* sections */
     KEEP(*(.jcr*))
     . = ALIGN(4);
     __data_end__ = .;        /* define a global symbol at data end */
+    __data_section_table_end = .;
   } > m_dtcm
 
   __RAM_FUNCTIONS_ROM = __DATA_ROM + (__data_end__ - __data_start__);
@@ -224,12 +226,14 @@ SECTIONS
     . = ALIGN(4);
     __START_BSS = .;
     __bss_start__ = .;
+    __bss_section_table = .;
     *(m_usb_dma_noninit_data)
     *(.bss)
     *(.bss*)
     *(COMMON)
     . = ALIGN(4);
     __bss_end__ = .;
+    __bss_section_table_end = .;
     __END_BSS = .;
   } > m_dtcm
 
@@ -253,6 +257,7 @@ SECTIONS
   /* Initializes stack on the end of block */
   __StackTop   = ORIGIN(m_dtcm) + LENGTH(m_dtcm);
   __StackLimit = __StackTop - STACK_SIZE;
+  _vStackTop = __StackTop;
   PROVIDE(__stack = __StackTop);
 
   .ARM.attributes 0 : { *(.ARM.attributes) }
diff --git a/ports/mimxrt/hal/flexspi_hyper_flash.c b/ports/mimxrt/hal/flexspi_hyper_flash.c
new file mode 100644
index 000000000..fb71d4d94
--- /dev/null
+++ b/ports/mimxrt/hal/flexspi_hyper_flash.c
@@ -0,0 +1,247 @@
+/*
+ * Copyright (c) 2016, Freescale Semiconductor, Inc.
+ * Copyright 2016-2021 NXP
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "fsl_clock.h"
+#include "flexspi_hyper_flash.h"
+
+// Copy of a few (pseudo-)functions from fsl_clock.h, which were nor reliably
+// inlined when they should be. That caused DEBUG mode to fail.
+// It does not increase the code size, since they were supposed to be inline.
+
+__attribute__((always_inline)) static inline void clock_set_div(clock_div_t divider, uint32_t value) {
+    uint32_t busyShift;
+
+    busyShift                   = CCM_TUPLE_BUSY_SHIFT(divider);
+    CCM_TUPLE_REG(CCM, divider) = (CCM_TUPLE_REG(CCM, divider) & (~CCM_TUPLE_MASK(divider))) |
+                                  (((uint32_t)((value) << CCM_TUPLE_SHIFT(divider))) & CCM_TUPLE_MASK(divider));
+
+    /* Clock switch need Handshake? */
+    if (CCM_NO_BUSY_WAIT != busyShift) {
+        /* Wait until CCM internal handshake finish. */
+        while (CCM->CDHIPR & (1U << busyShift)) {}
+    }
+}
+
+__attribute__((always_inline)) static inline void clock_control_gate(clock_ip_name_t name, clock_gate_value_t value) {
+    uint32_t index = ((uint32_t)name) >> 8U;
+    uint32_t shift = ((uint32_t)name) & 0x1FU;
+    volatile uint32_t *reg;
+
+    reg  = ((volatile uint32_t *)&CCM->CCGR0) + index;
+    *reg = ((*reg) & ~(3U << shift)) | (((uint32_t)value) << shift);
+}
+
+__attribute__((always_inline)) static inline void clock_enable_clock(clock_ip_name_t name) {
+    clock_control_gate(name, kCLOCK_ClockNeededRunWait);
+}
+
+__attribute__((always_inline)) static inline void clock_disable_clock(clock_ip_name_t name) {
+    clock_control_gate(name, kCLOCK_ClockNotNeeded);
+}
+
+#define DIV_PAGE_PGM	4
+#define DIV_ERASE_PGM	4
+#define DIV_READ		0
+
+static void SetFlexSPIDiv(uint32_t div) __attribute__((section(".ram_functions")));
+static void SetFlexSPIDiv(uint32_t div) {
+    FLEXSPI_Enable(FLEXSPI, false);
+    clock_disable_clock(kCLOCK_FlexSpi);
+    clock_set_div(kCLOCK_FlexspiDiv, div); /* flexspi clock 332M, DDR mode, internal clock 166M. */
+    clock_enable_clock(kCLOCK_FlexSpi);
+    FLEXSPI_Enable(FLEXSPI, true);	
+}
+
+status_t flexspi_nor_hyperbus_read(FLEXSPI_Type *base, uint32_t addr, uint32_t *buffer, uint32_t bytes) __attribute__((section(".ram_functions")));
+status_t flexspi_nor_hyperbus_read(FLEXSPI_Type *base, uint32_t addr, uint32_t *buffer, uint32_t bytes) {
+    flexspi_transfer_t flashXfer;
+    status_t status;
+
+    flashXfer.deviceAddress = addr * 2;
+    flashXfer.port          = kFLEXSPI_PortA1;
+    flashXfer.cmdType       = kFLEXSPI_Read;
+    flashXfer.SeqNumber     = 1;
+    flashXfer.seqIndex      = HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA;
+    flashXfer.data          = buffer;
+    flashXfer.dataSize      = bytes;
+    status                  = FLEXSPI_TransferBlocking(base, &flashXfer);
+
+    return status;
+}
+
+status_t flexspi_nor_hyperbus_write(FLEXSPI_Type *base, uint32_t addr, uint32_t *buffer, uint32_t bytes) __attribute__((section(".ram_functions")));
+status_t flexspi_nor_hyperbus_write(FLEXSPI_Type *base, uint32_t addr, uint32_t *buffer, uint32_t bytes) {
+    flexspi_transfer_t flashXfer;
+    status_t status;
+
+    flashXfer.deviceAddress = addr * 2;
+    flashXfer.port          = kFLEXSPI_PortA1;
+    flashXfer.cmdType       = kFLEXSPI_Write;
+    flashXfer.SeqNumber     = 1;
+    flashXfer.seqIndex      = HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA;
+    flashXfer.data          = buffer;
+    flashXfer.dataSize      = bytes;
+    status                  = FLEXSPI_TransferBlocking(base, &flashXfer);
+
+    return status;
+}
+
+status_t flexspi_nor_write_enable(FLEXSPI_Type *base, uint32_t baseAddr) __attribute__((section(".ram_functions")));
+status_t flexspi_nor_write_enable(FLEXSPI_Type *base, uint32_t baseAddr) {
+    flexspi_transfer_t flashXfer;
+    status_t status;
+
+    /* Write enable */
+    flashXfer.deviceAddress = baseAddr;
+    flashXfer.port          = kFLEXSPI_PortA1;
+    flashXfer.cmdType       = kFLEXSPI_Command;
+    flashXfer.SeqNumber     = 2;
+    flashXfer.seqIndex      = HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE;
+
+    status = FLEXSPI_TransferBlocking(base, &flashXfer);
+
+    return status;
+}
+
+status_t flexspi_nor_wait_bus_busy(FLEXSPI_Type *base) __attribute__((section(".ram_functions")));
+status_t flexspi_nor_wait_bus_busy(FLEXSPI_Type *base) {
+    /* Wait status ready. */
+    bool isBusy;
+    uint32_t readValue;
+    status_t status;
+    flexspi_transfer_t flashXfer;
+
+    flashXfer.deviceAddress = 0;
+    flashXfer.port          = kFLEXSPI_PortA1;
+    flashXfer.cmdType       = kFLEXSPI_Read;
+    flashXfer.SeqNumber     = 2;
+    flashXfer.seqIndex      = HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS;
+    flashXfer.data          = &readValue;
+    flashXfer.dataSize      = 2;
+
+    do {
+        status = FLEXSPI_TransferBlocking(base, &flashXfer);
+
+        if (status != kStatus_Success) {
+            return status;
+        }
+        if (readValue & 0x8000) {
+            isBusy = false;
+        } else {
+            isBusy = true;
+        }
+
+        if (readValue & 0x3200) {
+            status = kStatus_Fail;
+            break;
+        }
+
+    } while (isBusy);
+
+    return status;
+}
+
+status_t flexspi_nor_flash_erase_sector(FLEXSPI_Type *base, uint32_t address) __attribute__((section(".ram_functions")));
+status_t flexspi_nor_flash_erase_sector(FLEXSPI_Type *base, uint32_t address) {
+    status_t status;
+    flexspi_transfer_t flashXfer;
+
+    /* Write enable */
+    status = flexspi_nor_write_enable(base, address);
+
+    if (status != kStatus_Success) {
+        return status;
+    }
+
+    flashXfer.deviceAddress = address;
+    flashXfer.port          = kFLEXSPI_PortA1;
+    flashXfer.cmdType       = kFLEXSPI_Command;
+    flashXfer.SeqNumber     = 4;
+    flashXfer.seqIndex      = HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR;
+    status                  = FLEXSPI_TransferBlocking(base, &flashXfer);
+
+    if (status != kStatus_Success) {
+        return status;
+    }
+
+    status = flexspi_nor_wait_bus_busy(base);
+
+    return status;
+}
+
+status_t flexspi_nor_flash_page_program(FLEXSPI_Type *base, uint32_t address, const uint32_t *src,  uint32_t size ) __attribute__((section(".ram_functions")));
+status_t flexspi_nor_flash_page_program(FLEXSPI_Type *base, uint32_t address, const uint32_t *src,  uint32_t size) {
+    status_t status;
+    flexspi_transfer_t flashXfer;
+
+    /* Speed down flexspi clock */
+	SetFlexSPIDiv(DIV_PAGE_PGM);
+
+    /* Write enable */
+    status = flexspi_nor_write_enable(base, address);
+
+    if (status != kStatus_Success) {
+        return status;
+    }
+
+    /* Prepare page program command */
+    flashXfer.deviceAddress = address;
+    flashXfer.port          = kFLEXSPI_PortA1;
+    flashXfer.cmdType       = kFLEXSPI_Write;
+    flashXfer.SeqNumber     = 2;
+    flashXfer.seqIndex      = HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM;
+    flashXfer.data          = (uint32_t *)src;
+    flashXfer.dataSize      = size;
+    status                  = FLEXSPI_TransferBlocking(base, &flashXfer);
+
+    if (status != kStatus_Success) {
+        return status;
+    }
+
+    status = flexspi_nor_wait_bus_busy(base);
+
+	SetFlexSPIDiv(DIV_READ);
+
+    return status;
+}
+
+status_t flexspi_nor_hyperflash_cfi(FLEXSPI_Type *base) __attribute__((section(".ram_functions")));
+status_t flexspi_nor_hyperflash_cfi(FLEXSPI_Type *base) {
+    /*
+     * Read ID-CFI Parameters
+     */
+    // CFI Entry
+    status_t status;
+    uint32_t buffer[2];
+    uint8_t data[4] = {0x00, 0x98};
+    status          = flexspi_nor_hyperbus_write(base, 0x555, (uint32_t *)data, 2);
+    if (status != kStatus_Success) {
+        return status;
+    }
+
+    // ID-CFI Read
+    // Read Query Unique ASCII String
+    status = flexspi_nor_hyperbus_read(base, 0x10, &buffer[0], sizeof(buffer));
+    if (status != kStatus_Success) {
+        return status;
+    }
+    buffer[1] &= 0xFFFF;
+    // Check that the data read out is  unicode "QRY" in big-endian order
+    if ((buffer[0] != 0x52005100) || (buffer[1] != 0x5900)) {
+        status = kStatus_Fail;
+        return status;
+    }
+    // ASO Exit 0xF000
+    data[1] = 0xF0;
+    status  = flexspi_nor_hyperbus_write(base, 0x0, (uint32_t *)data, 2);
+    if (status != kStatus_Success) {
+        return status;
+    }
+
+    return status;
+}
diff --git a/ports/mimxrt/hal/flexspi_hyper_flash.h b/ports/mimxrt/hal/flexspi_hyper_flash.h
new file mode 100644
index 000000000..bba76c132
--- /dev/null
+++ b/ports/mimxrt/hal/flexspi_hyper_flash.h
@@ -0,0 +1,71 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_MIMXRT_HAL_FLEXSPI_HYPER_FLASH_H
+#define MICROPY_INCLUDED_MIMXRT_HAL_FLEXSPI_HYPER_FLASH_H
+
+#include "mpconfigboard.h"
+#include "fsl_flexspi.h"
+#include BOARD_FLASH_CONFIG_HEADER_H
+
+// Defined in boards flash_config.c
+extern flexspi_nor_config_t qspiflash_config;
+
+status_t flexspi_nor_hyperflash_cfi(FLEXSPI_Type *base);
+void flexspi_hyper_flash_init(void);
+void flexspi_nor_update_lut(void);
+status_t flexspi_nor_flash_erase_sector(FLEXSPI_Type *base, uint32_t address);
+status_t flexspi_nor_flash_page_program(FLEXSPI_Type *base, uint32_t address, const uint32_t *src, uint32_t size);
+
+static inline uint32_t flexspi_get_frequency(void) {
+    uint32_t div;
+    uint32_t fre;
+
+    /* Clock divider:
+       000 divided by 1
+       001 divided by 2
+       010 divided by 3
+       011 divided by 4
+       100 divided by 5
+       101 divided by 6
+       110 divided by 7
+       111 divided by 8
+     */
+    div = CLOCK_GetDiv(kCLOCK_FlexspiDiv);
+    /* Get frequency */
+    fre = CLOCK_GetFreq(kCLOCK_Usb1PllPfd0Clk) / (div + 0x01U);
+
+    return fre;
+}
+
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_READDATA    0
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEDATA   1
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_READSTATUS  2
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_WRITEENABLE 4
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_ERASESECTOR 6
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_PAGEPROGRAM 10
+#define HYPERFLASH_CMD_LUT_SEQ_IDX_ERASECHIP   12
+
+#endif // MICROPY_INCLUDED_MIMXRT_HAL_FLEXSPI_HYPER_FLASH_H
diff --git a/ports/mimxrt/hal/flexspi_nor_flash.h b/ports/mimxrt/hal/flexspi_nor_flash.h
index a9a9bbe70..c34df7416 100644
--- a/ports/mimxrt/hal/flexspi_nor_flash.h
+++ b/ports/mimxrt/hal/flexspi_nor_flash.h
@@ -39,4 +39,25 @@ void flexspi_nor_update_lut(void);
 status_t flexspi_nor_flash_erase_sector(FLEXSPI_Type *base, uint32_t address);
 status_t flexspi_nor_flash_page_program(FLEXSPI_Type *base, uint32_t address, const uint32_t *src, uint32_t size);
 
+static inline uint32_t flexspi_get_frequency(void) {
+    uint32_t div;
+    uint32_t fre;
+
+    /* Clock divider:
+       000 divided by 1
+       001 divided by 2
+       010 divided by 3
+       011 divided by 4
+       100 divided by 5
+       101 divided by 6
+       110 divided by 7
+       111 divided by 8
+     */
+    div = CLOCK_GetDiv(kCLOCK_FlexspiDiv);
+    /* Get frequency */
+    fre = CLOCK_GetFreq(kCLOCK_Usb1PllPfd0Clk) / (div + 0x01U);
+
+    return fre;
+}
+
 #endif // MICROPY_INCLUDED_MIMXRT_HAL_FLEXSPI_NOR_FLASH_H
diff --git a/ports/mimxrt/machine_i2c.c b/ports/mimxrt/machine_i2c.c
new file mode 100644
index 000000000..618d0a258
--- /dev/null
+++ b/ports/mimxrt/machine_i2c.c
@@ -0,0 +1,217 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020-2021 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "py/mperrno.h"
+#include "extmod/machine_i2c.h"
+#include "modmachine.h"
+
+#include "fsl_iomuxc.h"
+#include "fsl_lpi2c.h"
+
+#define DEFAULT_I2C_FREQ        (400000)
+#define DEFAULT_I2C_DRIVE       (6)
+
+// Select USB1 PLL (480 MHz) as master lpi2c clock source
+#define LPI2C_CLOCK_SOURCE_SELECT (0U)
+// Clock divider for master lpi2c clock source
+#define LPI2C_CLOCK_SOURCE_DIVIDER (1U)
+// Get frequency of lpi2c clock = 30 MHz
+#define LPI2C_CLOCK_FREQUENCY ((CLOCK_GetFreq(kCLOCK_Usb1PllClk) / 8) / (LPI2C_CLOCK_SOURCE_DIVIDER + 1U))
+
+typedef struct _machine_i2c_obj_t {
+    mp_obj_base_t base;
+    LPI2C_Type *i2c_inst;
+    uint8_t i2c_id;
+    uint8_t i2c_hw_id;
+    bool transfer_busy;
+    status_t transfer_status;
+    lpi2c_master_config_t *master_config;
+} machine_i2c_obj_t;
+
+typedef struct _iomux_table_t {
+    uint32_t muxRegister;
+    uint32_t muxMode;
+    uint32_t inputRegister;
+    uint32_t inputDaisy;
+    uint32_t configRegister;
+} iomux_table_t;
+
+STATIC const uint8_t i2c_index_table[] = MICROPY_HW_I2C_INDEX;
+STATIC LPI2C_Type *i2c_base_ptr_table[] = LPI2C_BASE_PTRS;
+static const iomux_table_t iomux_table[] = { IOMUX_TABLE_I2C };
+
+#define MICROPY_HW_I2C_NUM     ARRAY_SIZE(i2c_index_table)
+
+#define SCL (iomux_table[index])
+#define SDA (iomux_table[index + 1])
+
+bool lpi2c_set_iomux(int8_t hw_i2c, uint8_t drive) {
+    int index = (hw_i2c - 1) * 2;
+
+    if (SCL.muxRegister != 0) {
+        IOMUXC_SetPinMux(SCL.muxRegister, SCL.muxMode, SCL.inputRegister, SCL.inputDaisy, SCL.configRegister, 1U);
+        IOMUXC_SetPinConfig(SCL.muxRegister, SCL.muxMode, SCL.inputRegister, SCL.inputDaisy, SCL.configRegister,
+            0xF880u | drive << IOMUXC_SW_PAD_CTL_PAD_DSE_SHIFT);
+
+        IOMUXC_SetPinMux(SDA.muxRegister, SDA.muxMode, SDA.inputRegister, SDA.inputDaisy, SDA.configRegister, 1U);
+        IOMUXC_SetPinConfig(SDA.muxRegister, SDA.muxMode, SDA.inputRegister, SDA.inputDaisy, SDA.configRegister,
+            0xF880u | drive << IOMUXC_SW_PAD_CTL_PAD_DSE_SHIFT);
+        return true;
+    } else {
+        return false;
+    }
+}
+
+STATIC void machine_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_printf(print, "I2C(%u, freq=%u)",
+        self->i2c_id, self->master_config->baudRate_Hz);
+}
+
+mp_obj_t machine_i2c_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
+    enum { ARG_id, ARG_freq, ARG_drive};
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_freq, MP_ARG_INT, {.u_int = DEFAULT_I2C_FREQ} },
+        { MP_QSTR_drive, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = DEFAULT_I2C_DRIVE} },
+    };
+
+    static bool clk_init = true;
+
+    // Parse args.
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // Get I2C bus.
+    int i2c_id = mp_obj_get_int(args[ARG_id].u_obj);
+    if (i2c_id < 0 || i2c_id >= MICROPY_HW_I2C_NUM) {
+        mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("I2C(%d) doesn't exist"), i2c_id);
+    }
+
+    // Get I2C Object.
+    machine_i2c_obj_t *self = m_new_obj(machine_i2c_obj_t);
+    self->base.type = &machine_i2c_type;
+    self->i2c_id = i2c_id;
+    self->i2c_hw_id = i2c_index_table[i2c_id];  // the hw i2c number 1..n
+    self->i2c_inst = i2c_base_ptr_table[self->i2c_hw_id];
+
+    uint8_t drive = args[ARG_drive].u_int;
+    if (drive < 1 || drive > 7) {
+        drive = DEFAULT_I2C_DRIVE;
+    }
+
+    if (clk_init) {
+        clk_init = false;
+        // Set clock source for LPI2C
+        CLOCK_SetMux(kCLOCK_Lpi2cMux, LPI2C_CLOCK_SOURCE_SELECT); // USB1 PLL (480 MHz)
+        CLOCK_SetDiv(kCLOCK_Lpi2cDiv, LPI2C_CLOCK_SOURCE_DIVIDER);
+    }
+
+    // Initialise the I2C peripheral if any arguments given, or it was not initialised previously.
+    lpi2c_set_iomux(self->i2c_hw_id, drive);
+    self->master_config = m_new_obj(lpi2c_master_config_t);
+    LPI2C_MasterGetDefaultConfig(self->master_config);
+    // Initialise the I2C peripheral.
+    self->master_config->baudRate_Hz = args[ARG_freq].u_int;
+    LPI2C_MasterInit(self->i2c_inst, self->master_config, LPI2C_CLOCK_FREQUENCY);
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+static void lpi2c_master_callback(LPI2C_Type *base, lpi2c_master_handle_t *handle, status_t status, void *self_in) {
+    machine_i2c_obj_t *self = (machine_i2c_obj_t *)self_in;
+
+    self->transfer_busy = false;
+    self->transfer_status = status;
+}
+
+STATIC int machine_i2c_transfer_single(mp_obj_base_t *self_in, uint16_t addr, size_t len, uint8_t *buf, unsigned int flags) {
+    machine_i2c_obj_t *self = (machine_i2c_obj_t *)self_in;
+    status_t ret;
+    lpi2c_master_handle_t g_master_handle;
+    lpi2c_master_transfer_t masterXfer = {0};
+    LPI2C_MasterTransferCreateHandle(self->i2c_inst, &g_master_handle, lpi2c_master_callback, self);
+
+    if (flags & MP_MACHINE_I2C_FLAG_READ) {
+        masterXfer.direction = kLPI2C_Read;
+    } else {
+        masterXfer.direction = kLPI2C_Write;
+    }
+    if (addr < 0x80) {  // 7 or 10 bit address?
+        masterXfer.slaveAddress = addr;
+    } else {
+        masterXfer.slaveAddress = 0x78 | ((addr >> 8) & 0x03);
+        masterXfer.subaddress = addr & 0xff;
+        masterXfer.subaddressSize = 1;
+    }
+    masterXfer.data = buf;
+    masterXfer.dataSize = len;
+    if (flags & MP_MACHINE_I2C_FLAG_STOP) {
+        masterXfer.flags = kLPI2C_TransferDefaultFlag;
+    } else {
+        masterXfer.flags = kLPI2C_TransferNoStopFlag;
+    }
+    self->transfer_busy = true;
+
+    // Send master data to slave in non-blocking mode
+    ret = LPI2C_MasterTransferNonBlocking(self->i2c_inst, &g_master_handle, &masterXfer);
+    if (ret != kStatus_Success) {
+        return -MP_EIO;
+    }
+    //  Wait for the transfer to complete
+    while (self->transfer_busy) {
+        MICROPY_EVENT_POLL_HOOK
+    }
+
+    // Transfer will not send a stop in case of errors like NAK. So it's done here.
+    if (flags & MP_MACHINE_I2C_FLAG_STOP && self->transfer_status != kStatus_Success) {
+        LPI2C_MasterStop(self->i2c_inst);
+    }
+
+    if (self->transfer_status == kStatus_Success) {
+        return len;
+    } else if (self->transfer_status == kStatus_LPI2C_Nak) {
+        return -MP_ENODEV;
+    } else {
+        return -MP_EIO;
+    }
+}
+
+STATIC const mp_machine_i2c_p_t machine_i2c_p = {
+    .transfer = mp_machine_i2c_transfer_adaptor,
+    .transfer_single = machine_i2c_transfer_single,
+};
+
+const mp_obj_type_t machine_i2c_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_I2C,
+    .print = machine_i2c_print,
+    .make_new = machine_i2c_make_new,
+    .protocol = &machine_i2c_p,
+    .locals_dict = (mp_obj_dict_t *)&mp_machine_i2c_locals_dict,
+};
diff --git a/ports/mimxrt/machine_led.c b/ports/mimxrt/machine_led.c
index 07c7b180a..4082eb34b 100644
--- a/ports/mimxrt/machine_led.c
+++ b/ports/mimxrt/machine_led.c
@@ -44,7 +44,7 @@ STATIC mp_obj_t led_obj_make_new(const mp_obj_type_t *type, size_t n_args, size_
 
     // Check led id is in range
     if (!(1 <= led_id && led_id <= NUM_LEDS)) {
-        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "LED(%d) doesn't exist", led_id));
+        mp_raise_msg_varg(&mp_type_ValueError, "LED(%d) doesn't exist", led_id);
     }
 
     // Return reference to static object
diff --git a/ports/mimxrt/machine_pin.c b/ports/mimxrt/machine_pin.c
index dc26cdfc1..12975806d 100644
--- a/ports/mimxrt/machine_pin.c
+++ b/ports/mimxrt/machine_pin.c
@@ -31,7 +31,8 @@
 
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/mpirq.h"
+#include "extmod/virtpin.h"
 #include "pin.h"
 
 // Local functions
@@ -425,12 +426,34 @@ STATIC const mp_rom_map_elem_t machine_pin_locals_dict_table[] = {
 };
 STATIC MP_DEFINE_CONST_DICT(machine_pin_locals_dict, machine_pin_locals_dict_table);
 
+
+STATIC mp_uint_t machine_pin_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_t arg, int *errcode) {
+    (void)errcode;
+    machine_pin_obj_t *self = self_in;
+
+    switch (request) {
+        case MP_PIN_READ: {
+            return mp_hal_pin_read(self);
+        }
+        case MP_PIN_WRITE: {
+            mp_hal_pin_write(self, arg);
+            return 0;
+        }
+    }
+    return -1;
+}
+
+STATIC const mp_pin_p_t machine_pin_obj_protocol = {
+    .ioctl = machine_pin_ioctl,
+};
+
 const mp_obj_type_t machine_pin_type = {
     {&mp_type_type},
     .name = MP_QSTR_Pin,
     .print = machine_pin_obj_print,
     .call = machine_pin_obj_call,
     .make_new = mp_pin_make_new,
+    .protocol = &machine_pin_obj_protocol,
     .locals_dict = (mp_obj_dict_t *)&machine_pin_locals_dict,
 };
 
diff --git a/ports/mimxrt/machine_rtc.c b/ports/mimxrt/machine_rtc.c
index d00d139f7..f08e73fa5 100644
--- a/ports/mimxrt/machine_rtc.c
+++ b/ports/mimxrt/machine_rtc.c
@@ -26,7 +26,7 @@
  */
 
 #include "py/runtime.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "modmachine.h"
 #include "ticks.h"
 #include "fsl_snvs_lp.h"
diff --git a/ports/mimxrt/main.c b/ports/mimxrt/main.c
index c93e89c8a..e81974afa 100644
--- a/ports/mimxrt/main.c
+++ b/ports/mimxrt/main.c
@@ -30,9 +30,9 @@
 #include "py/gc.h"
 #include "py/mperrno.h"
 #include "py/stackctrl.h"
-#include "lib/mp-readline/readline.h"
-#include "lib/utils/gchelper.h"
-#include "lib/utils/pyexec.h"
+#include "shared/readline/readline.h"
+#include "shared/runtime/gchelper.h"
+#include "shared/runtime/pyexec.h"
 #include "ticks.h"
 #include "tusb.h"
 #include "led.h"
diff --git a/ports/mimxrt/mimxrt_flash.c b/ports/mimxrt/mimxrt_flash.c
index bf054c87f..79c4e676d 100644
--- a/ports/mimxrt/mimxrt_flash.c
+++ b/ports/mimxrt/mimxrt_flash.c
@@ -30,9 +30,10 @@
 #include "py/runtime.h"
 #include "extmod/vfs.h"
 #include "modmimxrt.h"
-#include "hal/flexspi_nor_flash.h"
+#include BOARD_FLASH_OPS_HEADER_H
 
 // BOARD_FLASH_SIZE is defined in mpconfigport.h
+
 #define SECTOR_SIZE_BYTES (qspiflash_config.sectorSize)
 #define PAGE_SIZE_BYTES (qspiflash_config.pageSize)
 
@@ -62,7 +63,7 @@ STATIC mimxrt_flash_obj_t mimxrt_flash_obj = {
 };
 
 // flash_erase_block(erase_addr_bytes)
-// erases the 4k sector starting at adddr
+// erases the sector starting at addr. Sector size according to the flash properties.
 status_t flash_erase_block(uint32_t erase_addr) __attribute__((section(".ram_functions")));
 status_t flash_erase_block(uint32_t erase_addr) {
     status_t status;
@@ -77,21 +78,31 @@ status_t flash_erase_block(uint32_t erase_addr) {
 
 // flash_write_block(flash_dest_addr_bytes, data_source, length_bytes)
 // writes length_byte data to the destination address
-// length is a multiple of the page size = 256
 // the vfs driver takes care for erasing the sector if required
 status_t flash_write_block(uint32_t dest_addr, const uint8_t *src, uint32_t length) __attribute__((section(".ram_functions")));
 status_t flash_write_block(uint32_t dest_addr, const uint8_t *src, uint32_t length) {
     status_t status;
+    uint32_t size;
+    uint32_t next_addr;
+
     SCB_CleanInvalidateDCache();
     SCB_DisableDCache();
-    // write sector in page size chunks
-    for (int i = 0; i < length; i += PAGE_SIZE_BYTES) {
+    // write data in chunks not crossing a page boundary
+    while (length > 0) {
+        next_addr = dest_addr - (dest_addr % PAGE_SIZE_BYTES) + PAGE_SIZE_BYTES; // next page boundary
+        size = next_addr - dest_addr;  // maximal chunk length
+        if (size > length) { // compare against remaining data size
+            size = length;
+        }
         __disable_irq();
-        status = flexspi_nor_flash_page_program(FLEXSPI, dest_addr + i, (uint32_t *)(src + i), PAGE_SIZE_BYTES);
+        status = flexspi_nor_flash_page_program(FLEXSPI, dest_addr, (uint32_t *)src, size);
         __enable_irq();
         if (status != kStatus_Success) {
             break;
         }
+        length -= size;
+        src += size;
+        dest_addr += size;
     }
     SCB_EnableDCache();
     return status;
@@ -105,7 +116,7 @@ STATIC mp_obj_t mimxrt_flash_make_new(const mp_obj_type_t *type, size_t n_args,
     // This should be performed by the boot ROM but for some reason it is not.
     FLEXSPI_UpdateLUT(FLEXSPI, 0,
         qspiflash_config.memConfig.lookupTable,
-        sizeof(qspiflash_config.memConfig.lookupTable) / sizeof(qspiflash_config.memConfig.lookupTable[0]));
+        ARRAY_SIZE(qspiflash_config.memConfig.lookupTable));
 
     // Configure FLEXSPI IP FIFO access.
     FLEXSPI->MCR0 &= ~(FLEXSPI_MCR0_ARDFEN_MASK);
diff --git a/ports/mimxrt/modmachine.c b/ports/mimxrt/modmachine.c
index e821f1507..150615ca0 100644
--- a/ports/mimxrt/modmachine.c
+++ b/ports/mimxrt/modmachine.c
@@ -85,6 +85,7 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_Signal),              MP_ROM_PTR(&machine_signal_type) },
     { MP_ROM_QSTR(MP_QSTR_SoftI2C),             MP_ROM_PTR(&mp_machine_soft_i2c_type) },
     { MP_ROM_QSTR(MP_QSTR_SoftSPI),             MP_ROM_PTR(&mp_machine_soft_spi_type) },
+    { MP_ROM_QSTR(MP_QSTR_I2C),                 MP_ROM_PTR(&machine_i2c_type) },
     { MP_ROM_QSTR(MP_QSTR_SPI),                 MP_ROM_PTR(&machine_spi_type) },
     { MP_ROM_QSTR(MP_QSTR_UART),                MP_ROM_PTR(&machine_uart_type) },
 
diff --git a/ports/mimxrt/modmachine.h b/ports/mimxrt/modmachine.h
index eba8e6db8..9732093bd 100644
--- a/ports/mimxrt/modmachine.h
+++ b/ports/mimxrt/modmachine.h
@@ -32,6 +32,7 @@
 extern const mp_obj_type_t machine_adc_type;
 extern const mp_obj_type_t machine_timer_type;
 extern const mp_obj_type_t machine_rtc_type;
+extern const mp_obj_type_t machine_i2c_type;
 extern const mp_obj_type_t machine_spi_type;
 extern const mp_obj_type_t machine_uart_type;
 
diff --git a/ports/mimxrt/modutime.c b/ports/mimxrt/modutime.c
index 2a88a4224..d3be7c2ea 100644
--- a/ports/mimxrt/modutime.c
+++ b/ports/mimxrt/modutime.c
@@ -26,7 +26,7 @@
  */
 
 #include "py/runtime.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "extmod/utime_mphal.h"
 #include "fsl_snvs_lp.h"
 
diff --git a/ports/mimxrt/mpconfigport.h b/ports/mimxrt/mpconfigport.h
index e1e102797..1066b93e1 100644
--- a/ports/mimxrt/mpconfigport.h
+++ b/ports/mimxrt/mpconfigport.h
@@ -145,6 +145,7 @@ __attribute__((always_inline)) static inline void enable_irq(uint32_t state) {
 
 __attribute__((always_inline)) static inline uint32_t disable_irq(void) {
     uint32_t state = __get_PRIMASK();
+    __disable_irq();
     return state;
 }
 
diff --git a/ports/mimxrt/mphalport.c b/ports/mimxrt/mphalport.c
index 942deae5b..ff7e988df 100644
--- a/ports/mimxrt/mphalport.c
+++ b/ports/mimxrt/mphalport.c
@@ -28,7 +28,7 @@
 #include "py/runtime.h"
 #include "py/stream.h"
 #include "py/mphal.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "ticks.h"
 #include "tusb.h"
 #include "fsl_snvs_lp.h"
diff --git a/ports/mimxrt/pin.h b/ports/mimxrt/pin.h
index ace4d1843..8d80490d1 100644
--- a/ports/mimxrt/pin.h
+++ b/ports/mimxrt/pin.h
@@ -29,7 +29,7 @@
 
 #include <stdint.h>
 #include "py/obj.h"
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/mpirq.h"
 #include "fsl_gpio.h"
 
 // ------------------------------------------------------------------------------------------------------------------ //
diff --git a/ports/mimxrt/tusb_port.c b/ports/mimxrt/tusb_port.c
index 2b1ccabbe..128861a49 100644
--- a/ports/mimxrt/tusb_port.c
+++ b/ports/mimxrt/tusb_port.c
@@ -26,8 +26,10 @@
 
 #include "tusb.h"
 
-#define USBD_VID (0xf055)
-#define USBD_PID (0x9802)
+#ifndef MICROPY_HW_USB_VID
+#define MICROPY_HW_USB_VID (0xf055)
+#define MICROPY_HW_USB_PID (0x9802)
+#endif
 
 #define USBD_DESC_LEN (TUD_CONFIG_DESC_LEN + TUD_CDC_DESC_LEN)
 #define USBD_MAX_POWER_MA (250)
@@ -57,8 +59,8 @@ static const tusb_desc_device_t usbd_desc_device = {
     .bDeviceSubClass = MISC_SUBCLASS_COMMON,
     .bDeviceProtocol = MISC_PROTOCOL_IAD,
     .bMaxPacketSize0 = CFG_TUD_ENDPOINT0_SIZE,
-    .idVendor = USBD_VID,
-    .idProduct = USBD_PID,
+    .idVendor = MICROPY_HW_USB_VID,
+    .idProduct = MICROPY_HW_USB_PID,
     .bcdDevice = 0x0100,
     .iManufacturer = USBD_STR_MANUF,
     .iProduct = USBD_STR_PRODUCT,
diff --git a/ports/minimal/Makefile b/ports/minimal/Makefile
index bce544ec1..21e3fe3f7 100644
--- a/ports/minimal/Makefile
+++ b/ports/minimal/Makefile
@@ -41,22 +41,37 @@ CFLAGS += -Os -DNDEBUG
 CFLAGS += -fdata-sections -ffunction-sections
 endif
 
+# Flags for optional C++ source code
+CXXFLAGS += $(filter-out -std=c99,$(CFLAGS))
+CXXFLAGS += $(CXXFLAGS_MOD)
+
+# Flags for user C modules
+CFLAGS += $(CFLAGS_MOD)
+LDFLAGS += $(LDFLAGS_MOD)
+
 LIBS =
 
 SRC_C = \
 	main.c \
 	uart_core.c \
-	lib/utils/printf.c \
-	lib/utils/stdout_helpers.c \
-	lib/utils/pyexec.c \
-	lib/mp-readline/readline.c \
+	shared/libc/printf.c \
+	shared/readline/readline.c \
+	shared/runtime/pyexec.c \
+	shared/runtime/stdout_helpers.c \
 	$(BUILD)/_frozen_mpy.c \
 
 ifeq ($(CROSS), 1)
-SRC_C += lib/libc/string0.c
+SRC_C += shared/libc/string0.c
 endif
 
-OBJ = $(PY_CORE_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
+SRC_C += $(SRC_MOD)
+
+SRC_CXX += $(SRC_MOD_CXX)
+
+SRC_QSTR += $(SRC_MOD) $(SRC_MOD_CXX)
+
+OBJ += $(PY_CORE_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
+OBJ += $(addprefix $(BUILD)/, $(SRC_CXX:.cpp=.o))
 
 ifeq ($(CROSS), 1)
 all: $(BUILD)/firmware.dfu
diff --git a/ports/minimal/main.c b/ports/minimal/main.c
index aa6d10ee3..006ca0a4d 100644
--- a/ports/minimal/main.c
+++ b/ports/minimal/main.c
@@ -7,7 +7,7 @@
 #include "py/repl.h"
 #include "py/gc.h"
 #include "py/mperrno.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 
 #if MICROPY_ENABLE_COMPILER
 void do_str(const char *src, mp_parse_input_kind_t input_kind) {
diff --git a/ports/nrf/Makefile b/ports/nrf/Makefile
index a3f914dbc..a8a522827 100644
--- a/ports/nrf/Makefile
+++ b/ports/nrf/Makefile
@@ -5,6 +5,8 @@ ifeq ($(wildcard boards/$(BOARD)/.),)
 $(error Invalid BOARD specified)
 endif
 
+BOARD_DIR ?= boards/$(BOARD)
+
 # If SoftDevice is selected, try to use that one.
 SD ?=
 SD_LOWER = $(shell echo $(SD) | tr '[:upper:]' '[:lower:]')
@@ -50,6 +52,8 @@ ifeq ($(DEBUG), 0)
 MICROPY_ROM_TEXT_COMPRESSION ?= 1
 endif
 
+FROZEN_MANIFEST ?= modules/manifest.py
+
 # include py core make definitions
 include ../../py/py.mk
 
@@ -70,7 +74,8 @@ INC += -I./modules/ubluepy
 INC += -I./modules/music
 INC += -I./modules/ble
 INC += -I./modules/board
-INC += -I../../lib/mp-readline
+INC += -I./modules/nrf
+INC += -I../../shared/readline
 INC += -I./drivers/bluetooth
 INC += -I./drivers
 INC += -I../../lib/nrfx/
@@ -129,6 +134,10 @@ LDFLAGS = $(CFLAGS)
 LDFLAGS += -Xlinker -Map=$(@:.elf=.map)
 LDFLAGS += -mthumb -mabi=aapcs $(addprefix -T,$(LD_FILES)) -L boards/
 
+ifneq ($(FS_SIZE),)
+LDFLAGS += -Wl,'--defsym=_fs_size=$(FS_SIZE)'
+endif
+
 #Debugging/Optimization
 ifeq ($(DEBUG), 1)
 #ASMFLAGS += -g -gtabs+
@@ -216,12 +225,12 @@ include drivers/secureboot/secureboot.mk
 
 endif
 
-SRC_LIB += $(addprefix lib/,\
+SRC_LIB += $(addprefix shared/,\
 	libc/string0.c \
-	mp-readline/readline.c \
-	utils/pyexec.c \
-	utils/sys_stdio_mphal.c \
-	utils/interrupt_char.c \
+	readline/readline.c \
+	runtime/pyexec.c \
+	runtime/sys_stdio_mphal.c \
+	runtime/interrupt_char.c \
 	timeutils/timeutils.c \
 	)
 
@@ -322,6 +331,8 @@ DRIVERS_SRC_C += $(addprefix modules/,\
 	music/modmusic.c \
 	music/musictunes.c \
 	ble/modble.c \
+	nrf/modnrf.c \
+	nrf/flashbdev.c \
 	)
 
 # Custom micropython startup file with smaller interrupt vector table
@@ -530,13 +541,13 @@ GEN_PINS_QSTR = $(BUILD)/pins_qstr.h
 GEN_PINS_AF_CONST = $(HEADER_BUILD)/pins_af_const.h
 GEN_PINS_AF_PY = $(BUILD)/pins_af.py
 
-ifneq ($(FROZEN_DIR),)
+ifneq ($(FROZEN_MANIFEST)$(FROZEN_DIR),)
 # To use frozen source modules, put your .py files in a subdirectory (eg scripts/)
 # and then invoke make with FROZEN_DIR=scripts (be sure to build from scratch).
 CFLAGS += -DMICROPY_MODULE_FROZEN_STR
 endif
 
-ifneq ($(FROZEN_MPY_DIR),)
+ifneq ($(FROZEN_MANIFEST)$(FROZEN_MPY_DIR),)
 # To use frozen bytecode, put your .py files in a subdirectory (eg frozen/) and
 # then invoke make with FROZEN_MPY_DIR=frozen (be sure to build from scratch).
 CFLAGS += -DMICROPY_QSTR_EXTRA_POOL=mp_qstr_frozen_const_pool
diff --git a/ports/nrf/README.md b/ports/nrf/README.md
index 0341cd81c..aa8968ff9 100644
--- a/ports/nrf/README.md
+++ b/ports/nrf/README.md
@@ -110,6 +110,22 @@ To use frozen modules, put them in a directory (e.g. `freeze/`) and supply
 
      make BOARD=pca10040 FROZEN_MPY_DIR=freeze
 
+## Compile with freeze manifest
+
+Freeze manifests can be used by definining `FROZEN_MANIFEST` pointing to a
+`manifest.py`. This can either be done by a `make` invocation or by defining
+it in the specific target board's `mpconfigboard.mk`.
+
+For example:
+
+    make BOARD=pca10040 FROZEN_MANIFEST=path/to/manifest.py
+
+In case of using the target board's makefile, add a line similar to this:
+
+    FROZEN_MANIFEST ?= $(BOARD_DIR)/manifest.py
+
+In these two examples, the manual `make` invocation will have precedence.
+
 ## Enable MICROPY_VFS_FAT
 As the `oofatfs` module is not having header guards that can exclude the implementation compile time, this port provides a flag to enable it explicitly. The MICROPY_VFS_FAT is by default set to 0 and has to be set to 1 if `oofatfs` files should be compiled. This will be in addition of setting `MICROPY_VFS` in mpconfigport.h.
 
@@ -117,6 +133,34 @@ For example:
 
      make BOARD=pca10040 MICROPY_VFS_FAT=1
 
+## Enable MICROPY_VFS_LFS1 or MICROPY_VFS_LFS2
+
+In order to enable `littlefs` as device flash filesystem, `MICROPY_VFS_LFS1`
+or `MICROPY_VFS_LFS2` can be set. This will be in addition of setting
+`MICROPY_VFS` in mpconfigport.h or mpconfigboard.h.
+
+For example:
+
+    make BOARD=pca10056 MICROPY_VFS_LFS2=1
+
+## Set file system size
+
+The size of the file system on the internal flash is configured by the linker
+script parameter `_fs_size`. This can either be overriden by the linker script
+or dynamically through the makefile. By seting a value to the `FS_SIZE`.
+The number will be passed directly to the linker scripts in order to calculate
+the start and end of the file system. Note that the parameter value must be in
+linker script syntax as it is passed directly.
+
+For example, if we want to override the default file system size set by the
+linker scripts to use 256K:
+
+    make BOARD=pca10056 MICROPY_VFS_LFS2=1 FS_SIZE=256K
+
+Also note that changing this size between builds might cause loss of files
+present from a previous firmware as it will format the file system due to a new
+location.
+
 ## Target Boards and Make Flags
 
 Target Board (BOARD) | Bluetooth Stack (SD)    | Bluetooth Support      | Bootloader     | Default Flash Util
diff --git a/ports/nrf/boards/actinius_icarus/mpconfigboard.mk b/ports/nrf/boards/actinius_icarus/mpconfigboard.mk
index c1e05fd30..8e6f75b36 100644
--- a/ports/nrf/boards/actinius_icarus/mpconfigboard.mk
+++ b/ports/nrf/boards/actinius_icarus/mpconfigboard.mk
@@ -4,3 +4,5 @@ MCU_SUB_VARIANT = nrf9160
 LD_FILES += boards/nrf9160_1M_256k.ld
 
 NRF_DEFINES += -DNRF9160_XXAA -DNRF_TRUSTZONE_NONSECURE 
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/arduino_primo/mpconfigboard.mk b/ports/nrf/boards/arduino_primo/mpconfigboard.mk
index 84685236b..e814d3d55 100644
--- a/ports/nrf/boards/arduino_primo/mpconfigboard.mk
+++ b/ports/nrf/boards/arduino_primo/mpconfigboard.mk
@@ -6,3 +6,5 @@ LD_FILES += boards/nrf52832_512k_64k.ld
 FLASHER = pyocd
 
 NRF_DEFINES += -DNRF52832_XXAA
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/blueio_tag_evim/mpconfigboard.mk b/ports/nrf/boards/blueio_tag_evim/mpconfigboard.mk
index 02a317744..c3164c8f0 100644
--- a/ports/nrf/boards/blueio_tag_evim/mpconfigboard.mk
+++ b/ports/nrf/boards/blueio_tag_evim/mpconfigboard.mk
@@ -6,3 +6,5 @@ LD_FILES += boards/nrf52832_512k_64k.ld
 FLASHER = idap
 
 NRF_DEFINES += -DNRF52832_XXAA
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/common.ld b/ports/nrf/boards/common.ld
index d2e5eef76..866336fa0 100644
--- a/ports/nrf/boards/common.ld
+++ b/ports/nrf/boards/common.ld
@@ -81,3 +81,5 @@ SECTIONS
 /* Define heap and stack areas */
 _ram_end = ORIGIN(RAM) + LENGTH(RAM);
 _estack = ORIGIN(RAM) + LENGTH(RAM);
+_unused_flash_start = (_sidata + (_edata - _sdata));
+_unused_flash_len = (ORIGIN(FLASH_TEXT) + LENGTH(FLASH_TEXT)) - _unused_flash_start;
diff --git a/ports/nrf/boards/dvk_bl652/mpconfigboard.mk b/ports/nrf/boards/dvk_bl652/mpconfigboard.mk
index 8730d0297..30767d766 100644
--- a/ports/nrf/boards/dvk_bl652/mpconfigboard.mk
+++ b/ports/nrf/boards/dvk_bl652/mpconfigboard.mk
@@ -6,3 +6,5 @@ LD_FILES += boards/nrf52832_512k_64k.ld
 
 NRF_DEFINES += -DNRF52832_XXAA
 CFLAGS += -DBLUETOOTH_LFCLK_RC
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/evk_nina_b1/mpconfigboard.mk b/ports/nrf/boards/evk_nina_b1/mpconfigboard.mk
index db64a60dd..96245e3e4 100644
--- a/ports/nrf/boards/evk_nina_b1/mpconfigboard.mk
+++ b/ports/nrf/boards/evk_nina_b1/mpconfigboard.mk
@@ -5,3 +5,5 @@ SOFTDEV_VERSION = 6.1.1
 LD_FILES += boards/nrf52832_512k_64k.ld
 
 NRF_DEFINES += -DNRF52832_XXAA
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/feather52/mpconfigboard.mk b/ports/nrf/boards/feather52/mpconfigboard.mk
index 5e0f336da..96245e3e4 100644
--- a/ports/nrf/boards/feather52/mpconfigboard.mk
+++ b/ports/nrf/boards/feather52/mpconfigboard.mk
@@ -6,3 +6,4 @@ LD_FILES += boards/nrf52832_512k_64k.ld
 
 NRF_DEFINES += -DNRF52832_XXAA
 
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/ibk_blyst_nano/mpconfigboard.mk b/ports/nrf/boards/ibk_blyst_nano/mpconfigboard.mk
index 02a317744..c3164c8f0 100644
--- a/ports/nrf/boards/ibk_blyst_nano/mpconfigboard.mk
+++ b/ports/nrf/boards/ibk_blyst_nano/mpconfigboard.mk
@@ -6,3 +6,5 @@ LD_FILES += boards/nrf52832_512k_64k.ld
 FLASHER = idap
 
 NRF_DEFINES += -DNRF52832_XXAA
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/idk_blyst_nano/mpconfigboard.mk b/ports/nrf/boards/idk_blyst_nano/mpconfigboard.mk
index 02a317744..c3164c8f0 100644
--- a/ports/nrf/boards/idk_blyst_nano/mpconfigboard.mk
+++ b/ports/nrf/boards/idk_blyst_nano/mpconfigboard.mk
@@ -6,3 +6,5 @@ LD_FILES += boards/nrf52832_512k_64k.ld
 FLASHER = idap
 
 NRF_DEFINES += -DNRF52832_XXAA
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/microbit/mpconfigboard.mk b/ports/nrf/boards/microbit/mpconfigboard.mk
index 96f430071..6fdd2bc50 100644
--- a/ports/nrf/boards/microbit/mpconfigboard.mk
+++ b/ports/nrf/boards/microbit/mpconfigboard.mk
@@ -2,9 +2,14 @@ MCU_SERIES = m0
 MCU_VARIANT = nrf51
 MCU_SUB_VARIANT = nrf51822
 SOFTDEV_VERSION = 8.0.0
+
 ifneq ($(SD),)
 LD_FILES += boards/microbit/custom_nrf51822_s110_microbit.ld
+FROZEN_MANIFEST ?=
+else
+MICROPY_VFS_LFS2 = 1
 endif
+
 LD_FILES += boards/nrf51x22_256k_16k.ld
 FLASHER = pyocd
 
diff --git a/ports/nrf/boards/nrf52840-mdk-usb-dongle/mpconfigboard.mk b/ports/nrf/boards/nrf52840-mdk-usb-dongle/mpconfigboard.mk
index ca437418d..3a26a92b7 100644
--- a/ports/nrf/boards/nrf52840-mdk-usb-dongle/mpconfigboard.mk
+++ b/ports/nrf/boards/nrf52840-mdk-usb-dongle/mpconfigboard.mk
@@ -17,3 +17,5 @@ endif
 LD_FILES += boards/nrf52840_1M_256k.ld
 
 NRF_DEFINES += -DNRF52840_XXAA
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/particle_xenon/mpconfigboard.mk b/ports/nrf/boards/particle_xenon/mpconfigboard.mk
index 34bead59f..d28324f76 100644
--- a/ports/nrf/boards/particle_xenon/mpconfigboard.mk
+++ b/ports/nrf/boards/particle_xenon/mpconfigboard.mk
@@ -9,3 +9,5 @@ NRF_DEFINES += -DNRF52840_XXAA
 # The nrf52-particle.cfg is not included here, it can be found in the Particle Workbench
 # Note: This requires openocd >0.10
 OPENOCD_TARGET ?= boards/$(BOARD)/nrf52-particle.cfg
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/pca10000/mpconfigboard.mk b/ports/nrf/boards/pca10000/mpconfigboard.mk
index c0cef5f3a..64cf513c0 100644
--- a/ports/nrf/boards/pca10000/mpconfigboard.mk
+++ b/ports/nrf/boards/pca10000/mpconfigboard.mk
@@ -3,3 +3,9 @@ MCU_VARIANT = nrf51
 MCU_SUB_VARIANT = nrf51822
 SOFTDEV_VERSION = 8.0.0
 LD_FILES += boards/nrf51x22_256k_16k.ld
+
+ifneq ($(SD),)
+FROZEN_MANIFEST ?=
+else
+MICROPY_VFS_LFS2 = 1
+endif
diff --git a/ports/nrf/boards/pca10001/mpconfigboard.mk b/ports/nrf/boards/pca10001/mpconfigboard.mk
index c0cef5f3a..64cf513c0 100644
--- a/ports/nrf/boards/pca10001/mpconfigboard.mk
+++ b/ports/nrf/boards/pca10001/mpconfigboard.mk
@@ -3,3 +3,9 @@ MCU_VARIANT = nrf51
 MCU_SUB_VARIANT = nrf51822
 SOFTDEV_VERSION = 8.0.0
 LD_FILES += boards/nrf51x22_256k_16k.ld
+
+ifneq ($(SD),)
+FROZEN_MANIFEST ?=
+else
+MICROPY_VFS_LFS2 = 1
+endif
diff --git a/ports/nrf/boards/pca10028/mpconfigboard.mk b/ports/nrf/boards/pca10028/mpconfigboard.mk
index b3c8f21ea..83b26a1de 100644
--- a/ports/nrf/boards/pca10028/mpconfigboard.mk
+++ b/ports/nrf/boards/pca10028/mpconfigboard.mk
@@ -3,3 +3,9 @@ MCU_VARIANT = nrf51
 MCU_SUB_VARIANT = nrf51822
 SOFTDEV_VERSION = 8.0.0
 LD_FILES += boards/nrf51x22_256k_32k.ld
+
+ifneq ($(SD),)
+FROZEN_MANIFEST ?=
+else
+MICROPY_VFS_LFS2 = 1
+endif
diff --git a/ports/nrf/boards/pca10031/mpconfigboard.mk b/ports/nrf/boards/pca10031/mpconfigboard.mk
index b3c8f21ea..83b26a1de 100644
--- a/ports/nrf/boards/pca10031/mpconfigboard.mk
+++ b/ports/nrf/boards/pca10031/mpconfigboard.mk
@@ -3,3 +3,9 @@ MCU_VARIANT = nrf51
 MCU_SUB_VARIANT = nrf51822
 SOFTDEV_VERSION = 8.0.0
 LD_FILES += boards/nrf51x22_256k_32k.ld
+
+ifneq ($(SD),)
+FROZEN_MANIFEST ?=
+else
+MICROPY_VFS_LFS2 = 1
+endif
diff --git a/ports/nrf/boards/pca10040/mpconfigboard.mk b/ports/nrf/boards/pca10040/mpconfigboard.mk
index db64a60dd..96245e3e4 100644
--- a/ports/nrf/boards/pca10040/mpconfigboard.mk
+++ b/ports/nrf/boards/pca10040/mpconfigboard.mk
@@ -5,3 +5,5 @@ SOFTDEV_VERSION = 6.1.1
 LD_FILES += boards/nrf52832_512k_64k.ld
 
 NRF_DEFINES += -DNRF52832_XXAA
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/pca10056/mpconfigboard.mk b/ports/nrf/boards/pca10056/mpconfigboard.mk
index ca555d393..d8ee0f8a2 100644
--- a/ports/nrf/boards/pca10056/mpconfigboard.mk
+++ b/ports/nrf/boards/pca10056/mpconfigboard.mk
@@ -5,3 +5,5 @@ SOFTDEV_VERSION = 6.1.1
 LD_FILES += boards/nrf52840_1M_256k.ld
 
 NRF_DEFINES += -DNRF52840_XXAA
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/pca10059/mpconfigboard.mk b/ports/nrf/boards/pca10059/mpconfigboard.mk
index ca437418d..3a26a92b7 100644
--- a/ports/nrf/boards/pca10059/mpconfigboard.mk
+++ b/ports/nrf/boards/pca10059/mpconfigboard.mk
@@ -17,3 +17,5 @@ endif
 LD_FILES += boards/nrf52840_1M_256k.ld
 
 NRF_DEFINES += -DNRF52840_XXAA
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/pca10090/mpconfigboard.mk b/ports/nrf/boards/pca10090/mpconfigboard.mk
index 9363900e2..cc7e7c368 100644
--- a/ports/nrf/boards/pca10090/mpconfigboard.mk
+++ b/ports/nrf/boards/pca10090/mpconfigboard.mk
@@ -4,3 +4,5 @@ MCU_SUB_VARIANT = nrf9160
 LD_FILES += boards/nrf9160_1M_256k.ld
 
 NRF_DEFINES += -DNRF9160_XXAA -DNRF_TRUSTZONE_NONSECURE
+
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/nrf/boards/wt51822_s4at/mpconfigboard.mk b/ports/nrf/boards/wt51822_s4at/mpconfigboard.mk
index 515de07f5..d0de24ba4 100644
--- a/ports/nrf/boards/wt51822_s4at/mpconfigboard.mk
+++ b/ports/nrf/boards/wt51822_s4at/mpconfigboard.mk
@@ -5,3 +5,9 @@ SOFTDEV_VERSION = 8.0.0
 LD_FILES += boards/nrf51x22_256k_16k.ld
 
 CFLAGS += -DBLUETOOTH_LFCLK_RC
+
+ifneq ($(SD),)
+FROZEN_MANIFEST ?=
+else
+MICROPY_VFS_LFS2 = 1
+endif
diff --git a/ports/nrf/drivers/bluetooth/ble_drv.c b/ports/nrf/drivers/bluetooth/ble_drv.c
index 3a15025cb..004058093 100644
--- a/ports/nrf/drivers/bluetooth/ble_drv.c
+++ b/ports/nrf/drivers/bluetooth/ble_drv.c
@@ -929,7 +929,7 @@ void ble_drv_discover_descriptors(void) {
 
 static void sd_evt_handler(uint32_t evt_id) {
     switch (evt_id) {
-#if MICROPY_MBFS
+#if MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE || MICROPY_MBFS
         case NRF_EVT_FLASH_OPERATION_SUCCESS:
             flash_operation_finished(FLASH_STATE_SUCCESS);
             break;
diff --git a/ports/nrf/drivers/bluetooth/ble_uart.c b/ports/nrf/drivers/bluetooth/ble_uart.c
index 96c2025d0..c3712fe8c 100644
--- a/ports/nrf/drivers/bluetooth/ble_uart.c
+++ b/ports/nrf/drivers/bluetooth/ble_uart.c
@@ -30,7 +30,7 @@
 #include "ble_uart.h"
 #include "ringbuffer.h"
 #include "mphalport.h"
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 #include "py/runtime.h"
 
 #if MICROPY_PY_SYS_STDFILES
diff --git a/ports/nrf/drivers/flash.c b/ports/nrf/drivers/flash.c
index 5a7256a0c..85e5f71d6 100644
--- a/ports/nrf/drivers/flash.c
+++ b/ports/nrf/drivers/flash.c
@@ -26,7 +26,7 @@
 
 #include "py/mpconfig.h"
 
-#if MICROPY_MBFS && BLUETOOTH_SD
+#if (MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE || MICROPY_MBFS) && BLUETOOTH_SD
 
 #include "drivers/flash.h"
 #include "drivers/bluetooth/ble_drv.h"
@@ -129,4 +129,4 @@ void flash_write_bytes(uint32_t dst, const uint8_t *src, uint32_t num_bytes) {
     }
 }
 
-#endif // MICROPY_MBFS
+#endif // (MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE || MICROPY_MBFS) && BLUETOOTH_SD
diff --git a/ports/nrf/drivers/usb/usb_descriptors.c b/ports/nrf/drivers/usb/usb_descriptors.c
index e9436ded5..b1edfcc18 100644
--- a/ports/nrf/drivers/usb/usb_descriptors.c
+++ b/ports/nrf/drivers/usb/usb_descriptors.c
@@ -26,8 +26,10 @@
 
 #include "tusb.h"
 
-#define USBD_VID (0xf055)
-#define USBD_PID (0x9802)
+#ifndef MICROPY_HW_USB_VID
+#define MICROPY_HW_USB_VID (0xf055)
+#define MICROPY_HW_USB_PID (0x9802)
+#endif
 
 #define USBD_DESC_LEN (TUD_CONFIG_DESC_LEN + TUD_CDC_DESC_LEN)
 #define USBD_MAX_POWER_MA (250)
@@ -57,8 +59,8 @@ static const tusb_desc_device_t usbd_desc_device = {
     .bDeviceSubClass    = MISC_SUBCLASS_COMMON,
     .bDeviceProtocol    = MISC_PROTOCOL_IAD,
     .bMaxPacketSize0    = CFG_TUD_ENDOINT0_SIZE,
-    .idVendor           = USBD_VID,
-    .idProduct          = USBD_PID,
+    .idVendor           = MICROPY_HW_USB_VID,
+    .idProduct          = MICROPY_HW_USB_PID,
     .bcdDevice          = 0x0100,
     .iManufacturer      = USBD_STR_MANUF,
     .iProduct           = USBD_STR_PRODUCT,
diff --git a/ports/nrf/main.c b/ports/nrf/main.c
index 86ba83342..254d9491c 100644
--- a/ports/nrf/main.c
+++ b/ports/nrf/main.c
@@ -38,7 +38,7 @@
 #include "py/stackctrl.h"
 #include "py/gc.h"
 #include "py/compile.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 #include "readline.h"
 #include "gccollect.h"
 #include "modmachine.h"
@@ -76,6 +76,13 @@
 #include "usb_cdc.h"
 #endif
 
+#if MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+#include "extmod/vfs_fat.h"
+#include "lib/oofatfs/ff.h"
+#include "extmod/vfs.h"
+#include "flashbdev.h"
+#endif
+
 void do_str(const char *src, mp_parse_input_kind_t input_kind) {
     mp_lexer_t *lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, src, strlen(src), 0);
     if (lex == NULL) {
@@ -99,6 +106,28 @@ void do_str(const char *src, mp_parse_input_kind_t input_kind) {
 extern uint32_t _heap_start;
 extern uint32_t _heap_end;
 
+#if MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+STATIC int vfs_mount_and_chdir(mp_obj_t bdev, mp_obj_t mount_point) {
+    nlr_buf_t nlr;
+    mp_int_t ret = -MP_EIO;
+    if (nlr_push(&nlr) == 0) {
+        mp_obj_t args[] = { bdev, mount_point };
+        mp_vfs_mount(2, args, (mp_map_t *)&mp_const_empty_map);
+        mp_vfs_chdir(mount_point);
+        ret = 0; // success
+        nlr_pop();
+    } else {
+        mp_obj_base_t *exc = nlr.ret_val;
+        if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(exc->type), MP_OBJ_FROM_PTR(&mp_type_OSError))) {
+            mp_obj_t v = mp_obj_exception_get_value(MP_OBJ_FROM_PTR(exc));
+            mp_obj_get_int_maybe(v, &ret); // get errno value
+            ret = -ret;
+        }
+    }
+    return ret;
+}
+#endif
+
 int main(int argc, char **argv) {
 
 
@@ -169,6 +198,23 @@ soft_reset:
 
     pin_init0();
 
+    #if MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+    flashbdev_init();
+
+    // Try to mount the flash on "/flash" and chdir to it for the boot-up directory.
+    mp_obj_t mount_point = MP_OBJ_NEW_QSTR(MP_QSTR__slash_flash);
+    int ret = vfs_mount_and_chdir((mp_obj_t)&nrf_flash_obj, mount_point);
+
+    if ((ret == -MP_ENODEV) || (ret == -MP_EIO)) {
+        pyexec_frozen_module("_mkfs.py"); // Frozen script for formatting flash filesystem.
+        ret = vfs_mount_and_chdir((mp_obj_t)&nrf_flash_obj, mount_point);
+    }
+
+    if (ret != 0) {
+        printf("MPY: can't mount flash\n");
+    }
+    #endif
+
     #if MICROPY_MBFS
     microbit_filesystem_init();
     #endif
diff --git a/ports/nrf/modules/board/modboard.c b/ports/nrf/modules/board/modboard.c
index 5f59a52a6..647af5035 100644
--- a/ports/nrf/modules/board/modboard.c
+++ b/ports/nrf/modules/board/modboard.c
@@ -25,7 +25,7 @@
  */
 
 #include "py/builtin.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 #include "py/runtime.h"
 #include "py/obj.h"
 #include "led.h"
diff --git a/ports/nrf/modules/machine/modmachine.c b/ports/nrf/modules/machine/modmachine.c
index 7e45b83df..fb3267e0d 100644
--- a/ports/nrf/modules/machine/modmachine.c
+++ b/ports/nrf/modules/machine/modmachine.c
@@ -33,7 +33,7 @@
 #include "extmod/machine_mem.h"
 #include "extmod/machine_pulse.h"
 #include "extmod/machine_i2c.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 #include "lib/oofatfs/ff.h"
 #include "lib/oofatfs/diskio.h"
 #include "gccollect.h"
diff --git a/ports/nrf/modules/machine/spi.c b/ports/nrf/modules/machine/spi.c
index 2510c2750..880d946a2 100644
--- a/ports/nrf/modules/machine/spi.c
+++ b/ports/nrf/modules/machine/spi.c
@@ -46,18 +46,18 @@
 #endif
 
 /// \moduleref machine
-/// \class SPI - a master-driven serial protocol
+/// \class SPI - a controller-driven serial protocol
 ///
-/// SPI is a serial protocol that is driven by a master.  At the physical level
+/// SPI is a serial protocol that is driven by a controller.  At the physical level
 /// there are 3 lines: SCK, MOSI, MISO.
 ///
 /// See usage model of I2C; SPI is very similar.  Main difference is
 /// parameters to init the SPI bus:
 ///
 ///     from machine import SPI
-///     spi = SPI(1, SPI.MASTER, baudrate=600000, polarity=1, phase=0, crc=0x7)
+///     spi = SPI(1, baudrate=600000, polarity=1, phase=0, crc=0x7)
 ///
-/// Only required parameter is mode, SPI.MASTER or SPI.SLAVE.  Polarity can be
+/// Polarity can be
 /// 0 or 1, and is the level the idle clock line sits at.  Phase can be 0 or 1
 /// to sample data on the first or second clock edge respectively.  Crc can be
 /// None for no CRC, or a polynomial specifier.
diff --git a/ports/nrf/modules/machine/uart.c b/ports/nrf/modules/machine/uart.c
index af95ae4b8..2cc421aa1 100644
--- a/ports/nrf/modules/machine/uart.c
+++ b/ports/nrf/modules/machine/uart.c
@@ -38,7 +38,7 @@
 #include "py/ringbuf.h"
 #include "pin.h"
 #include "genhdr/pins.h"
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 
 #include "uart.h"
 #include "mpconfigboard.h"
diff --git a/ports/nrf/modules/manifest.py b/ports/nrf/modules/manifest.py
new file mode 100644
index 000000000..4e8482226
--- /dev/null
+++ b/ports/nrf/modules/manifest.py
@@ -0,0 +1 @@
+freeze("$(PORT_DIR)/modules/scripts", "_mkfs.py")
diff --git a/ports/nrf/modules/nrf/flashbdev.c b/ports/nrf/modules/nrf/flashbdev.c
new file mode 100644
index 000000000..7a1296c5d
--- /dev/null
+++ b/ports/nrf/modules/nrf/flashbdev.c
@@ -0,0 +1,205 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Ayke van Laethem
+ * Copyright (c) 2019 Glenn Ruben Bakke
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include "py/runtime.h"
+#include "py/mperrno.h"
+
+#if MICROPY_PY_NRF && MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+
+#include "flashbdev.h"
+#include "flash.h"
+#include "extmod/vfs.h"
+
+extern byte _fs_start[];
+extern byte _fs_end[];
+
+#define FLASH_BLOCK_START (((uint32_t)_fs_start + (FLASH_PAGESIZE - 1)) / FLASH_PAGESIZE)
+
+typedef struct _nrf_flash_obj_t {
+    mp_obj_base_t base;
+    uint32_t start; // in bytes
+    uint32_t len; // in bytes
+} nrf_flash_obj_t;
+
+// This flash object represents the flash region defined by _fs_start and _fs_end
+// in memory.ld.  The start/len entries will be filled in by flashbdev_init().
+nrf_flash_obj_t nrf_flash_obj = {
+    { &nrf_flashbdev_type },
+    0,
+    0,
+};
+
+mp_obj_t nrf_flashbdev_readblocks(size_t n_args, const mp_obj_t *args) {
+    nrf_flash_obj_t *self = MP_OBJ_TO_PTR(args[0]);
+    uint32_t block_num = mp_obj_get_int(args[1]);
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(args[2], &bufinfo, MP_BUFFER_WRITE);
+
+    mp_int_t address = self->start + (block_num * FLASH_PAGESIZE);
+
+    if (n_args == 4) {
+        uint32_t offset = mp_obj_get_int(args[3]);
+        address += offset;
+    }
+
+    byte *buf = bufinfo.buf;
+    byte *p = (byte *)address;
+    memcpy(buf, p, bufinfo.len);
+
+    return MP_OBJ_NEW_SMALL_INT(0);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(nrf_flashbdev_readblocks_obj, 3, 4, nrf_flashbdev_readblocks);
+
+mp_obj_t nrf_flashbdev_writeblocks(size_t n_args, const mp_obj_t *args) {
+    nrf_flash_obj_t *self = MP_OBJ_TO_PTR(args[0]);
+    uint32_t block_num = mp_obj_get_int(args[1]);
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(args[2], &bufinfo, MP_BUFFER_WRITE);
+
+    mp_int_t address = self->start + (block_num * FLASH_PAGESIZE);
+
+    if (n_args == 4) {
+        uint32_t offset = mp_obj_get_int(args[3]);
+        address += offset;
+    } else {
+        flash_page_erase(address);
+    }
+
+    flash_write_bytes(address, bufinfo.buf, bufinfo.len);
+
+    return MP_OBJ_NEW_SMALL_INT(0);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(nrf_flashbdev_writeblocks_obj, 3, 4, nrf_flashbdev_writeblocks);
+
+mp_obj_t nrf_flashbdev_ioctl(mp_obj_t self_in, mp_obj_t op_in, mp_obj_t arg_in) {
+    nrf_flash_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_int_t op = mp_obj_get_int(op_in);
+    switch (op) {
+        case MP_BLOCKDEV_IOCTL_INIT: {
+            return MP_OBJ_NEW_SMALL_INT(0);
+        }
+
+        case MP_BLOCKDEV_IOCTL_DEINIT: {
+            return MP_OBJ_NEW_SMALL_INT(0);
+        }
+
+        case MP_BLOCKDEV_IOCTL_SYNC: {
+            return MP_OBJ_NEW_SMALL_INT(0);
+        }
+
+        case MP_BLOCKDEV_IOCTL_BLOCK_COUNT: {
+            return MP_OBJ_NEW_SMALL_INT(self->len / FLASH_PAGESIZE);
+        }
+
+        case MP_BLOCKDEV_IOCTL_BLOCK_SIZE: {
+            return MP_OBJ_NEW_SMALL_INT(FLASH_PAGESIZE);
+        }
+
+        case MP_BLOCKDEV_IOCTL_BLOCK_ERASE: {
+            mp_int_t block_num = mp_obj_get_int(arg_in);
+            mp_int_t address = self->start + (block_num * FLASH_PAGESIZE);
+
+            if ((address & 0x3) || (address % FLASH_PAGESIZE != 0)) {
+                return MP_OBJ_NEW_SMALL_INT(-MP_EIO);
+            }
+
+            flash_page_erase(address);
+            return MP_OBJ_NEW_SMALL_INT(0);
+        }
+
+        default:
+            return mp_const_none;
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_3(nrf_flashbdev_ioctl_obj, nrf_flashbdev_ioctl);
+
+STATIC const mp_rom_map_elem_t nrf_flashbdev_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_readblocks), MP_ROM_PTR(&nrf_flashbdev_readblocks_obj) },
+    { MP_ROM_QSTR(MP_QSTR_writeblocks), MP_ROM_PTR(&nrf_flashbdev_writeblocks_obj) },
+    { MP_ROM_QSTR(MP_QSTR_ioctl), MP_ROM_PTR(&nrf_flashbdev_ioctl_obj) },
+};
+STATIC MP_DEFINE_CONST_DICT(nrf_flashbdev_locals_dict, nrf_flashbdev_locals_dict_table);
+
+STATIC void nrf_flashbdev_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    nrf_flash_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_printf(print, "Flash(start=0x%08x, len=%u)", self->start, self->len);
+}
+
+STATIC mp_obj_t nrf_flashbdev_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
+    // Parse arguments
+    enum { ARG_start, ARG_len };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_start, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_len,   MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+    };
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    if (args[ARG_start].u_int == -1 && args[ARG_len].u_int == -1) {
+        return MP_OBJ_FROM_PTR(&nrf_flash_obj);
+    }
+
+    nrf_flash_obj_t *self = m_new_obj(nrf_flash_obj_t);
+    self->base.type = &nrf_flashbdev_type;
+
+    mp_int_t start = args[ARG_start].u_int;
+    mp_int_t len = args[ARG_len].u_int;
+
+    if ((start == -1) || (start % FLASH_PAGESIZE != 0)) {
+        mp_raise_ValueError(NULL);
+    }
+    if ((len == -1) || (len % FLASH_PAGESIZE != 0)) {
+        mp_raise_ValueError(NULL);
+    }
+
+    self->start = start;
+    self->len = len;
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+const mp_obj_type_t nrf_flashbdev_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_Flash,
+    .print = nrf_flashbdev_print,
+    .make_new = nrf_flashbdev_make_new,
+    .locals_dict = (mp_obj_dict_t *)&nrf_flashbdev_locals_dict,
+};
+
+void flashbdev_init(void) {
+    // Set start to first aligned page from _fs_start.
+    mp_int_t page_start = FLASH_BLOCK_START;
+    nrf_flash_obj.start = page_start * FLASH_PAGESIZE;
+    // Trim len to only count whole pages.
+    mp_int_t page_end = (uint32_t)_fs_end / FLASH_PAGESIZE;
+    mp_int_t num_pages = page_end - page_start;
+    nrf_flash_obj.len = num_pages * FLASH_PAGESIZE;
+}
+
+#endif // MICROPY_PY_NRF && MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
diff --git a/ports/nrf/modules/nrf/flashbdev.h b/ports/nrf/modules/nrf/flashbdev.h
new file mode 100644
index 000000000..29d7a12ed
--- /dev/null
+++ b/ports/nrf/modules/nrf/flashbdev.h
@@ -0,0 +1,39 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Ayke van Laethem
+ * Copyright (c) 2019 Glenn Ruben Bakke
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_NRF_FLASHBDEV_H
+#define MICROPY_INCLUDED_NRF_FLASHBDEV_H
+
+#include "py/obj.h"
+#include "extmod/vfs_fat.h"
+
+extern const struct _mp_obj_type_t nrf_flashbdev_type;
+extern struct _nrf_flash_obj_t nrf_flash_obj;
+
+void flashbdev_init(void);
+
+#endif // MICROPY_INCLUDED_NRF_FLASHBDEV_H
diff --git a/ports/nrf/modules/nrf/modnrf.c b/ports/nrf/modules/nrf/modnrf.c
new file mode 100644
index 000000000..fc217b1d7
--- /dev/null
+++ b/ports/nrf/modules/nrf/modnrf.c
@@ -0,0 +1,98 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Ayke van Laethem
+ * Copyright (c) 2019 Glenn Ruben Bakke
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+
+#if MICROPY_PY_NRF
+
+#include "flashbdev.h"
+#include "flash.h"
+#include "nrf_power.h"
+
+#if BLUETOOTH_SD
+#include "nrf_soc.h"
+#include "ble_drv.h"
+#define BLUETOOTH_STACK_ENABLED() (ble_drv_stack_enabled())
+#endif
+
+#define FLASH_PAGE_ALIGN_UP(addr)   (((addr) - 1) + (FLASH_PAGESIZE)-(((addr) - 1) % (FLASH_PAGESIZE)))
+
+extern uint32_t _unused_flash_start;
+extern uint32_t _unused_flash_len;
+
+#if NRF_POWER_HAS_DCDCEN
+STATIC mp_obj_t dcdc(size_t n_args, const mp_obj_t *args) {
+    if (n_args > 0) {
+        bool dcdc_state = mp_obj_is_true(args[0]);
+        #if BLUETOOTH_SD
+        if (BLUETOOTH_STACK_ENABLED()) {
+            sd_power_dcdc_mode_set(dcdc_state);
+        } else
+        #endif
+        {
+            nrf_power_dcdcen_set(NRF_POWER, dcdc_state);
+        }
+    }
+    return mp_obj_new_bool(nrf_power_dcdcen_get(NRF_POWER));
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(dcdc_obj, 0, 1, dcdc);
+#endif
+
+#if MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+mp_obj_t nrf_modnrf_freeflash_start_aligned(void) {
+    return mp_obj_new_int_from_uint(FLASH_PAGE_ALIGN_UP((uint32_t)&_unused_flash_start));
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(nrf_modnrf_freeflash_start_aligned_obj, nrf_modnrf_freeflash_start_aligned);
+
+mp_obj_t nrf_modnrf_freeflash_length_aligned(void) {
+    uint32_t align_diff = FLASH_PAGE_ALIGN_UP((uint32_t)&_unused_flash_start) - ((uint32_t)&_unused_flash_start);
+    uint32_t temp_len = ((uint32_t)&_unused_flash_len) - align_diff;
+    uint32_t len_page_aligned = (temp_len / FLASH_PAGESIZE) * FLASH_PAGESIZE;
+    return mp_obj_new_int_from_uint(len_page_aligned);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(nrf_modnrf_freeflash_length_aligned_obj, nrf_modnrf_freeflash_length_aligned);
+#endif
+
+STATIC const mp_rom_map_elem_t nrf_module_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_nrf) },
+    #if NRF_POWER_HAS_DCDCEN
+    { MP_ROM_QSTR(MP_QSTR_dcdc), MP_ROM_PTR(&dcdc_obj) },
+    #endif
+    #if MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+    { MP_ROM_QSTR(MP_QSTR_Flash), MP_ROM_PTR(&nrf_flashbdev_type) },
+    { MP_ROM_QSTR(MP_QSTR_unused_flash_start), MP_ROM_PTR(&nrf_modnrf_freeflash_start_aligned_obj) },
+    { MP_ROM_QSTR(MP_QSTR_unused_flash_length), MP_ROM_PTR(&nrf_modnrf_freeflash_length_aligned_obj) },
+    #endif
+};
+STATIC MP_DEFINE_CONST_DICT(nrf_module_globals, nrf_module_globals_table);
+
+const mp_obj_module_t nrf_module = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t *)&nrf_module_globals,
+};
+
+#endif // MICROPY_PY_NRF
diff --git a/ports/nrf/modules/scripts/_mkfs.py b/ports/nrf/modules/scripts/_mkfs.py
new file mode 100644
index 000000000..00522ffbb
--- /dev/null
+++ b/ports/nrf/modules/scripts/_mkfs.py
@@ -0,0 +1,23 @@
+import uos, nrf
+
+try:
+    from uos import VfsLfs1
+
+    uos.VfsLfs1.mkfs(nrf.Flash())
+except ImportError:
+    try:
+        from uos import VfsLfs2
+
+        uos.VfsLfs2.mkfs(nrf.Flash())
+    except ImportError:
+        try:
+            from uos import VfsFat
+
+            uos.VfsFat.mkfs(nrf.Flash())
+        except ImportError:
+            pass
+        except OSError as e:
+            if e.args[0] == 5:  # I/O Error
+                flashbdev_size = (nrf.Flash.ioctl(4, 0) * nrf.Flash.ioctl(5, 0)) // 1024
+                print()
+                print("Is `FS_SIZE=%iK` enough for FAT filesystem?" % flashbdev_size)
diff --git a/ports/nrf/modules/uos/moduos.c b/ports/nrf/modules/uos/moduos.c
index 98a5661f4..e8a3790da 100644
--- a/ports/nrf/modules/uos/moduos.c
+++ b/ports/nrf/modules/uos/moduos.c
@@ -36,6 +36,7 @@
 #include "modules/uos/microbitfs.h"
 #include "extmod/vfs.h"
 #include "extmod/vfs_fat.h"
+#include "extmod/vfs_lfs.h"
 #include "genhdr/mpversion.h"
 #include "uart.h"
 
@@ -85,10 +86,12 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_0(os_uname_obj, os_uname);
 /// \function sync()
 /// Sync all filesystems.
 STATIC mp_obj_t os_sync(void) {
+    #if MICROPY_VFS_FAT
     for (mp_vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
         // this assumes that vfs->obj is fs_user_mount_t with block device functions
         disk_ioctl(MP_OBJ_TO_PTR(vfs->obj), CTRL_SYNC, NULL);
     }
+    #endif
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_0(mod_os_sync_obj, os_sync);
@@ -142,6 +145,7 @@ STATIC const mp_rom_map_elem_t os_module_globals_table[] = {
 #if MICROPY_VFS
     { MP_ROM_QSTR(MP_QSTR_chdir), MP_ROM_PTR(&mp_vfs_chdir_obj) },
     { MP_ROM_QSTR(MP_QSTR_getcwd), MP_ROM_PTR(&mp_vfs_getcwd_obj) },
+    { MP_ROM_QSTR(MP_QSTR_ilistdir), MP_ROM_PTR(&mp_vfs_ilistdir_obj) },
     { MP_ROM_QSTR(MP_QSTR_listdir), MP_ROM_PTR(&mp_vfs_listdir_obj) },
     { MP_ROM_QSTR(MP_QSTR_mkdir), MP_ROM_PTR(&mp_vfs_mkdir_obj) },
     { MP_ROM_QSTR(MP_QSTR_remove), MP_ROM_PTR(&mp_vfs_remove_obj) },
@@ -174,7 +178,15 @@ STATIC const mp_rom_map_elem_t os_module_globals_table[] = {
 #if MICROPY_VFS
     { MP_ROM_QSTR(MP_QSTR_mount), MP_ROM_PTR(&mp_vfs_mount_obj) },
     { MP_ROM_QSTR(MP_QSTR_umount), MP_ROM_PTR(&mp_vfs_umount_obj) },
+    #if MICROPY_VFS_FAT
     { MP_ROM_QSTR(MP_QSTR_VfsFat), MP_ROM_PTR(&mp_fat_vfs_type) },
+    #endif
+    #if MICROPY_VFS_LFS1
+    { MP_ROM_QSTR(MP_QSTR_VfsLfs1), MP_ROM_PTR(&mp_type_vfs_lfs1) },
+    #endif
+    #if MICROPY_VFS_LFS2
+    { MP_ROM_QSTR(MP_QSTR_VfsLfs2), MP_ROM_PTR(&mp_type_vfs_lfs2) },
+    #endif
 #endif
 };
 
diff --git a/ports/nrf/mpconfigdevice_nrf51822.h b/ports/nrf/mpconfigdevice_nrf51822.h
index 2f85c9f4c..67a81d250 100644
--- a/ports/nrf/mpconfigdevice_nrf51822.h
+++ b/ports/nrf/mpconfigdevice_nrf51822.h
@@ -27,15 +27,31 @@
 // Board overridable build configuration.
 
 #ifndef MICROPY_MBFS
+#if defined(BLUETOOTH_SD)
 #define MICROPY_MBFS                       (1)
+#else
+#define MICROPY_MBFS                       (0)
+#endif
 #endif
 
 #ifndef MICROPY_VFS
+#if defined(BLUETOOTH_SD)
 #define MICROPY_VFS                        (0)
+#else
+#define MICROPY_VFS                        (1)
+#endif
 #endif
 
 // Board overridable feature configuration.
 
+#ifndef MICROPY_ENABLE_SOURCE_LINE
+#if defined(BLUETOOTH_SD)
+#define MICROPY_ENABLE_SOURCE_LINE         (0)
+#else
+#define MICROPY_ENABLE_SOURCE_LINE         (1)
+#endif
+#endif
+
 #ifndef MICROPY_PY_ARRAY_SLICE_ASSIGN
 #if defined(BLUETOOTH_SD)
 #define MICROPY_PY_ARRAY_SLICE_ASSIGN      (0)
@@ -59,3 +75,23 @@
 #define MICROPY_PY_UBINASCII               (1)
 #endif
 #endif
+
+// Board overridable port specific feature configuration.
+
+#ifndef MICROPY_PY_NRF
+#if defined(BLUETOOTH_SD)
+#define MICROPY_PY_NRF                     (0)
+#else
+#define MICROPY_PY_NRF                     (1)
+#endif
+#endif
+
+// Board overridable hardware configuration.
+
+#ifndef MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+#if defined(BLUETOOTH_SD)
+#define MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE (0)
+#else
+#define MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE (1)
+#endif
+#endif
diff --git a/ports/nrf/mpconfigdevice_nrf52832.h b/ports/nrf/mpconfigdevice_nrf52832.h
index 2bfd047ca..fa9258f2a 100644
--- a/ports/nrf/mpconfigdevice_nrf52832.h
+++ b/ports/nrf/mpconfigdevice_nrf52832.h
@@ -27,15 +27,19 @@
 // Board overridable build configuration.
 
 #ifndef MICROPY_MBFS
-#define MICROPY_MBFS                       (1)
+#define MICROPY_MBFS                       (0)
 #endif
 
 #ifndef MICROPY_VFS
-#define MICROPY_VFS                        (0)
+#define MICROPY_VFS                        (1)
 #endif
 
 // Board overridable feature configuration.
 
+#ifndef MICROPY_ENABLE_SOURCE_LINE
+#define MICROPY_ENABLE_SOURCE_LINE         (1)
+#endif
+
 #ifndef MICROPY_PY_ARRAY_SLICE_ASSIGN
 #define MICROPY_PY_ARRAY_SLICE_ASSIGN      (1)
 #endif
@@ -47,3 +51,15 @@
 #ifndef MICROPY_PY_UBINASCII
 #define MICROPY_PY_UBINASCII               (1)
 #endif
+
+// Board overridable port specific feature configuration.
+
+#ifndef MICROPY_PY_NRF
+#define MICROPY_PY_NRF                     (1)
+#endif
+
+// Board overridable hardware configuration.
+
+#ifndef MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+#define MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE (1)
+#endif
diff --git a/ports/nrf/mpconfigdevice_nrf52840.h b/ports/nrf/mpconfigdevice_nrf52840.h
index 2bfd047ca..581c52ea8 100644
--- a/ports/nrf/mpconfigdevice_nrf52840.h
+++ b/ports/nrf/mpconfigdevice_nrf52840.h
@@ -27,15 +27,29 @@
 // Board overridable build configuration.
 
 #ifndef MICROPY_MBFS
-#define MICROPY_MBFS                       (1)
+#define MICROPY_MBFS                       (0)
 #endif
 
 #ifndef MICROPY_VFS
-#define MICROPY_VFS                        (0)
+#define MICROPY_VFS                        (1)
+#endif
+
+// Board overridable emitter configuration.
+
+#ifndef MICROPY_EMIT_THUMB
+#define MICROPY_EMIT_THUMB          (1)
+#endif
+
+#ifndef MICROPY_EMIT_INLINE_THUMB
+#define MICROPY_EMIT_INLINE_THUMB   (1)
 #endif
 
 // Board overridable feature configuration.
 
+#ifndef MICROPY_ENABLE_SOURCE_LINE
+#define MICROPY_ENABLE_SOURCE_LINE         (1)
+#endif
+
 #ifndef MICROPY_PY_ARRAY_SLICE_ASSIGN
 #define MICROPY_PY_ARRAY_SLICE_ASSIGN      (1)
 #endif
@@ -47,3 +61,15 @@
 #ifndef MICROPY_PY_UBINASCII
 #define MICROPY_PY_UBINASCII               (1)
 #endif
+
+// Board overridable port specific feature configuration.
+
+#ifndef MICROPY_PY_NRF
+#define MICROPY_PY_NRF                     (1)
+#endif
+
+// Board overridable hardware configuration.
+
+#ifndef MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+#define MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE (1)
+#endif
diff --git a/ports/nrf/mpconfigdevice_nrf9160.h b/ports/nrf/mpconfigdevice_nrf9160.h
index 2bfd047ca..581c52ea8 100644
--- a/ports/nrf/mpconfigdevice_nrf9160.h
+++ b/ports/nrf/mpconfigdevice_nrf9160.h
@@ -27,15 +27,29 @@
 // Board overridable build configuration.
 
 #ifndef MICROPY_MBFS
-#define MICROPY_MBFS                       (1)
+#define MICROPY_MBFS                       (0)
 #endif
 
 #ifndef MICROPY_VFS
-#define MICROPY_VFS                        (0)
+#define MICROPY_VFS                        (1)
+#endif
+
+// Board overridable emitter configuration.
+
+#ifndef MICROPY_EMIT_THUMB
+#define MICROPY_EMIT_THUMB          (1)
+#endif
+
+#ifndef MICROPY_EMIT_INLINE_THUMB
+#define MICROPY_EMIT_INLINE_THUMB   (1)
 #endif
 
 // Board overridable feature configuration.
 
+#ifndef MICROPY_ENABLE_SOURCE_LINE
+#define MICROPY_ENABLE_SOURCE_LINE         (1)
+#endif
+
 #ifndef MICROPY_PY_ARRAY_SLICE_ASSIGN
 #define MICROPY_PY_ARRAY_SLICE_ASSIGN      (1)
 #endif
@@ -47,3 +61,15 @@
 #ifndef MICROPY_PY_UBINASCII
 #define MICROPY_PY_UBINASCII               (1)
 #endif
+
+// Board overridable port specific feature configuration.
+
+#ifndef MICROPY_PY_NRF
+#define MICROPY_PY_NRF                     (1)
+#endif
+
+// Board overridable hardware configuration.
+
+#ifndef MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+#define MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE (1)
+#endif
diff --git a/ports/nrf/mpconfigport.h b/ports/nrf/mpconfigport.h
index 183fdf681..8a622d811 100644
--- a/ports/nrf/mpconfigport.h
+++ b/ports/nrf/mpconfigport.h
@@ -43,7 +43,7 @@
 #define MICROPY_VFS                 (0)
 #endif
 #define MICROPY_ALLOC_PATH_MAX      (512)
-#define MICROPY_PERSISTENT_CODE_LOAD (0)
+#define MICROPY_PERSISTENT_CODE_LOAD (1)
 #define MICROPY_COMP_MODULE_CONST   (0)
 #define MICROPY_COMP_TRIPLE_TUPLE_ASSIGN (0)
 #define MICROPY_READER_VFS          (MICROPY_VFS)
@@ -55,7 +55,6 @@
 #define MICROPY_REPL_EMACS_KEYS     (0)
 #define MICROPY_REPL_AUTO_INDENT    (1)
 #define MICROPY_KBD_EXCEPTION       (1)
-#define MICROPY_ENABLE_SOURCE_LINE  (0)
 #define MICROPY_LONGINT_IMPL        (MICROPY_LONGINT_IMPL_MPZ)
 #if NRF51
 #define MICROPY_FLOAT_IMPL          (MICROPY_FLOAT_IMPL_NONE)
@@ -75,7 +74,13 @@
 #define MICROPY_FATFS_LFN_CODE_PAGE    437 /* 1=SFN/ANSI 437=LFN/U.S.(OEM) */
 #define MICROPY_FATFS_USE_LABEL        (1)
 #define MICROPY_FATFS_RPATH            (2)
-#define MICROPY_FATFS_MULTI_PARTITION  (1)
+#define MICROPY_FATFS_MULTI_PARTITION  (0)
+
+#if NRF51
+    #define MICROPY_FATFS_MAX_SS       (1024)
+#else
+    #define MICROPY_FATFS_MAX_SS       (4096)
+#endif
 
 // TODO these should be generic, not bound to fatfs
 #define mp_type_fileio fatfs_type_fileio
@@ -98,7 +103,7 @@
 #define MICROPY_CAN_OVERRIDE_BUILTINS (1)
 #define MICROPY_USE_INTERNAL_ERRNO  (1)
 #define MICROPY_PY_FUNCTION_ATTRS   (1)
-#define MICROPY_PY_BUILTINS_STR_UNICODE (0)
+#define MICROPY_PY_BUILTINS_STR_UNICODE (1)
 #define MICROPY_PY_BUILTINS_STR_CENTER (0)
 #define MICROPY_PY_BUILTINS_STR_PARTITION (0)
 #define MICROPY_PY_BUILTINS_STR_SPLITLINES (0)
@@ -120,7 +125,7 @@
 #define MICROPY_PY_MATH_SPECIAL_FUNCTIONS (0)
 #define MICROPY_PY_CMATH            (0)
 #define MICROPY_PY_IO               (0)
-#define MICROPY_PY_IO_FILEIO        (0)
+#define MICROPY_PY_IO_FILEIO        (MICROPY_VFS_FAT || MICROPY_VFS_LFS1 || MICROPY_VFS_LFS2)
 #define MICROPY_PY_URANDOM          (1)
 #define MICROPY_PY_URANDOM_EXTRA_FUNCS (1)
 #define MICROPY_PY_UCTYPES          (0)
@@ -179,6 +184,10 @@
 #define MICROPY_PY_TIME_TICKS       (1)
 #endif
 
+#ifndef MICROPY_PY_NRF
+#define MICROPY_PY_NRF              (0)
+#endif
+
 #define MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF   (1)
 #define MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE  (0)
 
@@ -212,11 +221,18 @@ typedef long mp_off_t;
 // extra built in modules to add to the list of known ones
 extern const struct _mp_obj_module_t board_module;
 extern const struct _mp_obj_module_t machine_module;
+extern const struct _mp_obj_module_t nrf_module;
 extern const struct _mp_obj_module_t mp_module_utime;
 extern const struct _mp_obj_module_t mp_module_uos;
 extern const struct _mp_obj_module_t mp_module_ubluepy;
 extern const struct _mp_obj_module_t music_module;
 
+#if MICROPY_PY_NRF
+#define NRF_MODULE                          { MP_ROM_QSTR(MP_QSTR_nrf), MP_ROM_PTR(&nrf_module) },
+#else
+#define NRF_MODULE
+#endif
+
 #if MICROPY_PY_UBLUEPY
 #define UBLUEPY_MODULE                      { MP_ROM_QSTR(MP_QSTR_ubluepy), MP_ROM_PTR(&mp_module_ubluepy) },
 #else
@@ -255,6 +271,7 @@ extern const struct _mp_obj_module_t ble_module;
     MUSIC_MODULE \
     UBLUEPY_MODULE \
     MICROPY_BOARD_BUILTINS \
+    NRF_MODULE \
 
 
 #else
@@ -266,6 +283,7 @@ extern const struct _mp_obj_module_t ble_module;
     { MP_ROM_QSTR(MP_QSTR_uos), MP_ROM_PTR(&mp_module_uos) }, \
     MUSIC_MODULE \
     MICROPY_BOARD_BUILTINS \
+    NRF_MODULE \
 
 
 #endif // BLUETOOTH_SD
diff --git a/ports/nrf/mphalport.c b/ports/nrf/mphalport.c
index b8e4c2e4d..8ffb25601 100644
--- a/ports/nrf/mphalport.c
+++ b/ports/nrf/mphalport.c
@@ -150,6 +150,10 @@ mp_uint_t mp_hal_ticks_ms(void) {
 
 #endif
 
+uint64_t mp_hal_time_ns(void) {
+    return 0;
+}
+
 // this table converts from HAL_StatusTypeDef to POSIX errno
 const byte mp_hal_status_to_errno_table[4] = {
     [HAL_OK] = 0,
diff --git a/ports/nrf/mphalport.h b/ports/nrf/mphalport.h
index 5900559b5..1ba4b6e70 100644
--- a/ports/nrf/mphalport.h
+++ b/ports/nrf/mphalport.h
@@ -78,4 +78,3 @@ mp_uint_t mp_hal_ticks_ms(void);
 #define mp_hal_ticks_cpu() (0)
 
 #endif
-
diff --git a/ports/nrf/nrfx_glue.h b/ports/nrf/nrfx_glue.h
index b4a60257a..56e1f719d 100644
--- a/ports/nrf/nrfx_glue.h
+++ b/ports/nrf/nrfx_glue.h
@@ -27,8 +27,15 @@
 #ifndef NRFX_GLUE_H
 #define NRFX_GLUE_H
 
+#include "py/mpconfig.h"
+#include "py/misc.h"
+
 #include <soc/nrfx_irqs.h>
 
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE MP_ARRAY_SIZE
+#endif
+
 #define NRFX_STATIC_ASSERT(expression)
 
 #define NRFX_ASSERT(expression)  do { bool res = expression; (void)res; } while (0)
diff --git a/ports/nrf/qstrdefsport.h b/ports/nrf/qstrdefsport.h
index 9608dbb24..3cc2f1e64 100644
--- a/ports/nrf/qstrdefsport.h
+++ b/ports/nrf/qstrdefsport.h
@@ -27,6 +27,12 @@
 // qstrs specific to this port
 // *FORMAT-OFF*
 
+// Entries for sys.path
+Q(/flash)
+
+// For uos.sep
+Q(/)
+
 Q(a)
 Q(a#)
 Q(a#:1)
@@ -138,4 +144,3 @@ Q(r4:2)
 Q(r:1)
 Q(r:2)
 Q(r:3)
-
diff --git a/ports/pic16bit/Makefile b/ports/pic16bit/Makefile
index 3c2bd54ea..f0d55ec87 100644
--- a/ports/pic16bit/Makefile
+++ b/ports/pic16bit/Makefile
@@ -39,9 +39,9 @@ SRC_C = \
 	modpyb.c \
 	modpybled.c \
 	modpybswitch.c \
-	lib/utils/pyexec.c \
-	lib/utils/sys_stdio_mphal.c \
-	lib/mp-readline/readline.c \
+	shared/runtime/pyexec.c \
+	shared/runtime/sys_stdio_mphal.c \
+	shared/readline/readline.c \
 
 SRC_S = \
 #	gchelper.s \
diff --git a/ports/pic16bit/main.c b/ports/pic16bit/main.c
index 07db3f582..adb927607 100644
--- a/ports/pic16bit/main.c
+++ b/ports/pic16bit/main.c
@@ -34,8 +34,8 @@
 #include "py/gc.h"
 #include "py/mphal.h"
 #include "py/mperrno.h"
-#include "lib/utils/pyexec.h"
-#include "lib/mp-readline/readline.h"
+#include "shared/runtime/pyexec.h"
+#include "shared/readline/readline.h"
 #include "board.h"
 #include "modpyb.h"
 
diff --git a/ports/powerpc/Makefile b/ports/powerpc/Makefile
index 1f5ec80d4..cca170dc0 100644
--- a/ports/powerpc/Makefile
+++ b/ports/powerpc/Makefile
@@ -34,11 +34,11 @@ LIBS =
 SRC_C = \
 	main.c \
 	uart_$(UART).c \
-	lib/utils/printf.c \
-	lib/utils/stdout_helpers.c \
-	lib/utils/pyexec.c \
-	lib/libc/string0.c \
-	lib/mp-readline/readline.c \
+	shared/libc/printf.c \
+	shared/libc/string0.c \
+	shared/readline/readline.c \
+	shared/runtime/pyexec.c \
+	shared/runtime/stdout_helpers.c \
 	$(BUILD)/_frozen_mpy.c \
 
 OBJ = $(PY_CORE_O)
diff --git a/ports/powerpc/main.c b/ports/powerpc/main.c
index fdeec13ab..a66d737c1 100644
--- a/ports/powerpc/main.c
+++ b/ports/powerpc/main.c
@@ -32,7 +32,7 @@
 #include "py/gc.h"
 #include "py/mperrno.h"
 #include "py/stackctrl.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 
 void __stack_chk_fail(void);
 void __stack_chk_fail(void) {
diff --git a/ports/qemu-arm/Makefile b/ports/qemu-arm/Makefile
index 22d0bf39c..4a6d63a01 100644
--- a/ports/qemu-arm/Makefile
+++ b/ports/qemu-arm/Makefile
@@ -16,7 +16,7 @@ ifeq ($(BOARD),netduino2)
 CFLAGS += -mthumb -mcpu=cortex-m3 -mfloat-abi=soft
 CFLAGS += -DQEMU_SOC_STM32
 LDSCRIPT = stm32.ld
-SRC_BOARD_O = lib/utils/gchelper_native.o lib/utils/gchelper_m3.o
+SRC_BOARD_O = shared/runtime/gchelper_native.o shared/runtime/gchelper_m3.o
 MPY_CROSS_FLAGS += -march=armv7m
 endif
 
@@ -25,7 +25,7 @@ CFLAGS += -mthumb -mcpu=cortex-m0 -mfloat-abi=soft
 CFLAGS += -DQEMU_SOC_NRF51
 LDSCRIPT = nrf51.ld
 QEMU_EXTRA = -global nrf51-soc.flash-size=1048576 -global nrf51-soc.sram-size=262144
-SRC_BOARD_O = lib/utils/gchelper_native.o lib/utils/gchelper_m0.o
+SRC_BOARD_O = shared/runtime/gchelper_native.o shared/runtime/gchelper_m0.o
 MPY_CROSS_FLAGS += -march=armv7m
 endif
 
@@ -33,7 +33,7 @@ ifeq ($(BOARD),mps2-an385)
 CFLAGS += -mthumb -mcpu=cortex-m3 -mfloat-abi=soft
 CFLAGS += -DQEMU_SOC_MPS2
 LDSCRIPT = mps2.ld
-SRC_BOARD_O = lib/utils/gchelper_native.o lib/utils/gchelper_m3.o
+SRC_BOARD_O = shared/runtime/gchelper_native.o shared/runtime/gchelper_m3.o
 MPY_CROSS_FLAGS += -march=armv7m
 endif
 
@@ -42,7 +42,7 @@ CFLAGS += -mcpu=cortex-a9
 CFLAGS += -DQEMU_SOC_IMX6
 LDSCRIPT = imx6.ld
 QEMU_EXTRA = -m 128M
-SRC_BOARD_O = lib/utils/gchelper_generic.o
+SRC_BOARD_O = shared/runtime/gchelper_generic.o
 # It's really armv7a but closest supported value is armv6.
 MPY_CROSS_FLAGS += -march=armv6
 endif
@@ -79,6 +79,8 @@ SRC_COMMON_C = \
 	uart.c \
 	moduos.c \
 	modmachine.c \
+	shared/libc/string0.c \
+	shared/runtime/sys_stdio_mphal.c \
 
 SRC_RUN_C = \
 	main.c \
@@ -88,7 +90,6 @@ SRC_TEST_C = \
 	lib/tinytest/tinytest.c \
 
 LIB_SRC_C += $(addprefix lib/,\
-	libc/string0.c \
 	libm/math.c \
 	libm/fmodf.c \
 	libm/nearbyintf.c \
@@ -108,7 +109,6 @@ LIB_SRC_C += $(addprefix lib/,\
 	libm/atanf.c \
 	libm/atan2f.c \
 	libm/roundf.c \
-	utils/sys_stdio_mphal.c \
 	)
 
 OBJ_COMMON =
diff --git a/ports/qemu-arm/Makefile.test b/ports/qemu-arm/Makefile.test
index b4ad6114b..e0f3a5416 100644
--- a/ports/qemu-arm/Makefile.test
+++ b/ports/qemu-arm/Makefile.test
@@ -1,4 +1,4 @@
-LIB_SRC_C = lib/upytesthelper/upytesthelper.c
+LIB_SRC_C = shared/upytesthelper/upytesthelper.c
 
 FROZEN_MANIFEST ?= "freeze('test-frzmpy')"
 
diff --git a/ports/qemu-arm/mpconfigport.h b/ports/qemu-arm/mpconfigport.h
index 1f05719ca..270995979 100644
--- a/ports/qemu-arm/mpconfigport.h
+++ b/ports/qemu-arm/mpconfigport.h
@@ -74,7 +74,7 @@ extern const struct _mp_obj_module_t mp_module_uos;
 #include <alloca.h>
 
 #ifdef TEST
-#include "lib/upytesthelper/upytesthelper.h"
+#include "shared/upytesthelper/upytesthelper.h"
 #undef MP_PLAT_PRINT_STRN
 #define MP_PLAT_PRINT_STRN(str, len) upytest_output(str, len)
 #endif
diff --git a/ports/qemu-arm/test_main.c b/ports/qemu-arm/test_main.c
index a59a8de0a..284b28731 100644
--- a/ports/qemu-arm/test_main.c
+++ b/ports/qemu-arm/test_main.c
@@ -11,7 +11,7 @@
 #include "py/stackctrl.h"
 #include "py/gc.h"
 #include "py/mperrno.h"
-#include "lib/utils/gchelper.h"
+#include "shared/runtime/gchelper.h"
 #include "lib/tinytest/tinytest.h"
 #include "lib/tinytest/tinytest_macros.h"
 
diff --git a/ports/rp2/CMakeLists.txt b/ports/rp2/CMakeLists.txt
index 2d6037712..fd7ec65e0 100644
--- a/ports/rp2/CMakeLists.txt
+++ b/ports/rp2/CMakeLists.txt
@@ -64,16 +64,16 @@ set(MICROPY_SOURCE_LIB
     ${MICROPY_DIR}/lib/littlefs/lfs1_util.c
     ${MICROPY_DIR}/lib/littlefs/lfs2.c
     ${MICROPY_DIR}/lib/littlefs/lfs2_util.c
-    ${MICROPY_DIR}/lib/mp-readline/readline.c
     ${MICROPY_DIR}/lib/oofatfs/ff.c
     ${MICROPY_DIR}/lib/oofatfs/ffunicode.c
-    ${MICROPY_DIR}/lib/timeutils/timeutils.c
-    ${MICROPY_DIR}/lib/utils/gchelper_m0.s
-    ${MICROPY_DIR}/lib/utils/gchelper_native.c
-    ${MICROPY_DIR}/lib/utils/mpirq.c
-    ${MICROPY_DIR}/lib/utils/pyexec.c
-    ${MICROPY_DIR}/lib/utils/stdout_helpers.c
-    ${MICROPY_DIR}/lib/utils/sys_stdio_mphal.c
+    ${MICROPY_DIR}/shared/readline/readline.c
+    ${MICROPY_DIR}/shared/runtime/gchelper_m0.s
+    ${MICROPY_DIR}/shared/runtime/gchelper_native.c
+    ${MICROPY_DIR}/shared/runtime/mpirq.c
+    ${MICROPY_DIR}/shared/runtime/pyexec.c
+    ${MICROPY_DIR}/shared/runtime/stdout_helpers.c
+    ${MICROPY_DIR}/shared/runtime/sys_stdio_mphal.c
+    ${MICROPY_DIR}/shared/timeutils/timeutils.c
 )
 
 set(MICROPY_SOURCE_DRIVERS
@@ -108,8 +108,8 @@ set(MICROPY_SOURCE_QSTR
     ${MICROPY_SOURCE_PY}
     ${MICROPY_SOURCE_EXTMOD}
     ${MICROPY_SOURCE_USERMOD}
-    ${MICROPY_DIR}/lib/utils/mpirq.c
-    ${MICROPY_DIR}/lib/utils/sys_stdio_mphal.c
+    ${MICROPY_DIR}/shared/runtime/mpirq.c
+    ${MICROPY_DIR}/shared/runtime/sys_stdio_mphal.c
     ${PROJECT_SOURCE_DIR}/machine_adc.c
     ${PROJECT_SOURCE_DIR}/machine_i2c.c
     ${PROJECT_SOURCE_DIR}/machine_pin.c
@@ -163,7 +163,9 @@ set(PICO_SDK_COMPONENTS
 
 # Define mpy-cross flags and frozen manifest
 set(MICROPY_CROSS_FLAGS -march=armv7m)
-set(MICROPY_FROZEN_MANIFEST ${PROJECT_SOURCE_DIR}/boards/manifest.py)
+if (NOT MICROPY_FROZEN_MANIFEST)
+    set(MICROPY_FROZEN_MANIFEST ${PROJECT_SOURCE_DIR}/boards/manifest.py)
+endif()
 
 target_sources(${MICROPY_TARGET} PRIVATE
     ${MICROPY_SOURCE_PY}
@@ -188,6 +190,20 @@ target_compile_options(${MICROPY_TARGET} PRIVATE
     -Werror
 )
 
+set_source_files_properties(
+    ${PICO_SDK_PATH}/src/rp2_common/pico_double/double_math.c
+    ${PICO_SDK_PATH}/src/rp2_common/pico_float/float_math.c
+    PROPERTIES
+    COMPILE_OPTIONS "-Wno-error=uninitialized"
+)
+
+set_source_files_properties(
+    ${PICO_TINYUSB_PATH}/src/portable/raspberrypi/rp2040/dcd_rp2040.c
+    ${PICO_TINYUSB_PATH}/src/portable/raspberrypi/rp2040/rp2040_usb.c
+    PROPERTIES
+    COMPILE_OPTIONS "-Wno-error=array-bounds;-Wno-error=unused-but-set-variable"
+)
+
 target_compile_definitions(${MICROPY_TARGET} PRIVATE
     FFCONF_H=\"${MICROPY_OOFATFS_DIR}/ffconf.h\"
     LFS1_NO_MALLOC LFS1_NO_DEBUG LFS1_NO_WARN LFS1_NO_ERROR LFS1_NO_ASSERT
@@ -206,6 +222,13 @@ target_link_libraries(${MICROPY_TARGET}
     ${PICO_SDK_COMPONENTS}
 )
 
+if (MICROPY_HW_ENABLE_DOUBLE_TAP)
+# Enable double tap reset into bootrom.
+target_link_libraries(${MICROPY_TARGET}
+    pico_bootsel_via_double_reset
+)
+endif()
+
 # todo this is a bit brittle, but we want to move a few source files into RAM (which requires
 #  a linker script modification) until we explicitly add  macro calls around the function
 #  defs to move them into RAM.
diff --git a/ports/rp2/Makefile b/ports/rp2/Makefile
index 246f29dd0..2af13bfbb 100644
--- a/ports/rp2/Makefile
+++ b/ports/rp2/Makefile
@@ -20,3 +20,8 @@ all:
 
 clean:
 	$(RM) -rf $(BUILD)
+
+GIT_SUBMODULES += lib/pico-sdk lib/tinyusb
+
+submodules:
+	$(MAKE) -f ../../py/mkrules.mk GIT_SUBMODULES="$(GIT_SUBMODULES)" submodules
diff --git a/ports/rp2/README.md b/ports/rp2/README.md
index d49550c5c..5836ac0cd 100644
--- a/ports/rp2/README.md
+++ b/ports/rp2/README.md
@@ -29,6 +29,7 @@ Building of the RP2 firmware is done entirely using CMake, although a simple
 Makefile is also provided as a convenience.  To build the firmware run (from
 this directory):
 
+    $ make submodules
     $ make clean
     $ make
 
diff --git a/ports/rp2/boards/ADAFRUIT_FEATHER_RP2040/mpconfigboard.h b/ports/rp2/boards/ADAFRUIT_FEATHER_RP2040/mpconfigboard.h
index 5068d3554..84d2bf20d 100644
--- a/ports/rp2/boards/ADAFRUIT_FEATHER_RP2040/mpconfigboard.h
+++ b/ports/rp2/boards/ADAFRUIT_FEATHER_RP2040/mpconfigboard.h
@@ -1,3 +1,20 @@
-// Board and hardware specific configuration
-#define MICROPY_HW_BOARD_NAME                   "Adafruit Feather RP2040"
-#define MICROPY_HW_FLASH_STORAGE_BYTES          (3072 * 1024)
+// https://www.adafruit.com/product/4884
+// https://learn.adafruit.com/adafruit-feather-rp2040-pico/pinouts
+
+#define MICROPY_HW_BOARD_NAME          "Adafruit Feather RP2040"
+#define MICROPY_HW_FLASH_STORAGE_BYTES (7 * 1024 * 1024)
+
+#define MICROPY_HW_USB_VID (0x239A)
+#define MICROPY_HW_USB_PID (0x80F2)
+
+// STEMMA QT / Qwiic on I2C1
+#define MICROPY_HW_I2C1_SCL  (3)
+#define MICROPY_HW_I2C1_SDA  (2)
+
+#define MICROPY_HW_SPI0_SCK  (18)
+#define MICROPY_HW_SPI0_MOSI (19)
+#define MICROPY_HW_SPI0_MISO (20)
+
+// NeoPixel GPIO16, power not toggleable
+
+// Red user LED GPIO13
diff --git a/ports/rp2/boards/ADAFRUIT_ITSYBITSY_RP2040/mpconfigboard.cmake b/ports/rp2/boards/ADAFRUIT_ITSYBITSY_RP2040/mpconfigboard.cmake
new file mode 100644
index 000000000..711e24ed5
--- /dev/null
+++ b/ports/rp2/boards/ADAFRUIT_ITSYBITSY_RP2040/mpconfigboard.cmake
@@ -0,0 +1 @@
+# cmake file for Adafruit ItsyBitsy RP2040
diff --git a/ports/rp2/boards/ADAFRUIT_ITSYBITSY_RP2040/mpconfigboard.h b/ports/rp2/boards/ADAFRUIT_ITSYBITSY_RP2040/mpconfigboard.h
new file mode 100644
index 000000000..8f5551172
--- /dev/null
+++ b/ports/rp2/boards/ADAFRUIT_ITSYBITSY_RP2040/mpconfigboard.h
@@ -0,0 +1,21 @@
+// https://www.adafruit.com/product/4888
+// https://learn.adafruit.com/adafruit-itsybitsy-rp2040/pinouts
+
+#define MICROPY_HW_BOARD_NAME          "Adafruit ItsyBitsy RP2040"
+#define MICROPY_HW_FLASH_STORAGE_BYTES (7 * 1024 * 1024)
+
+#define MICROPY_HW_USB_VID (0x239A)
+#define MICROPY_HW_USB_PID (0x80FE)
+
+#define MICROPY_HW_I2C0_SCL  (3)
+#define MICROPY_HW_I2C0_SDA  (2)
+
+#define MICROPY_HW_SPI0_SCK  (18)
+#define MICROPY_HW_SPI0_MOSI (19)
+#define MICROPY_HW_SPI0_MISO (20)
+
+// NeoPixel data GPIO17, power GPIO16
+
+// Red user LED GPIO11
+
+// Boot button GPIO13
diff --git a/ports/rp2/boards/ADAFRUIT_QTPY_RP2040/mpconfigboard.cmake b/ports/rp2/boards/ADAFRUIT_QTPY_RP2040/mpconfigboard.cmake
new file mode 100644
index 000000000..799ced5cd
--- /dev/null
+++ b/ports/rp2/boards/ADAFRUIT_QTPY_RP2040/mpconfigboard.cmake
@@ -0,0 +1 @@
+# cmake file for Adafruit QT Py RP2040
diff --git a/ports/rp2/boards/ADAFRUIT_QTPY_RP2040/mpconfigboard.h b/ports/rp2/boards/ADAFRUIT_QTPY_RP2040/mpconfigboard.h
new file mode 100644
index 000000000..ca341cedd
--- /dev/null
+++ b/ports/rp2/boards/ADAFRUIT_QTPY_RP2040/mpconfigboard.h
@@ -0,0 +1,28 @@
+// https://www.adafruit.com/product/4900
+// https://learn.adafruit.com/adafruit-qt-py-2040/pinouts
+
+#define MICROPY_HW_BOARD_NAME          "Adafruit QT Py RP2040"
+#define MICROPY_HW_FLASH_STORAGE_BYTES (7 * 1024 * 1024)
+
+#define MICROPY_HW_USB_VID (0x239A)
+#define MICROPY_HW_USB_PID (0x80F8)
+
+#define MICROPY_HW_UART1_TX  (20)
+#define MICROPY_HW_UART1_RX  (5)
+#define MICROPY_HW_UART1_CTS (10)
+#define MICROPY_HW_UART1_RTS (7)
+
+#define MICROPY_HW_I2C0_SCL  (25)
+#define MICROPY_HW_I2C0_SDA  (24)
+
+// STEMMA QT / Qwiic on I2C1
+#define MICROPY_HW_I2C1_SCL  (23)
+#define MICROPY_HW_I2C1_SDA  (22)
+
+#define MICROPY_HW_SPI0_SCK  (6)
+#define MICROPY_HW_SPI0_MOSI (3)
+#define MICROPY_HW_SPI0_MISO (4)
+
+// NeoPixel data GPIO12, power GPIO11
+
+// Boot button GPIO21
diff --git a/ports/rp2/boards/PIMORONI_PICOLIPO_16MB/mpconfigboard.cmake b/ports/rp2/boards/PIMORONI_PICOLIPO_16MB/mpconfigboard.cmake
new file mode 100644
index 000000000..b98ff4495
--- /dev/null
+++ b/ports/rp2/boards/PIMORONI_PICOLIPO_16MB/mpconfigboard.cmake
@@ -0,0 +1 @@
+# cmake file for Pimoroni Pico LiPo 16MB
diff --git a/ports/rp2/boards/PIMORONI_PICOLIPO_16MB/mpconfigboard.h b/ports/rp2/boards/PIMORONI_PICOLIPO_16MB/mpconfigboard.h
new file mode 100644
index 000000000..68478f761
--- /dev/null
+++ b/ports/rp2/boards/PIMORONI_PICOLIPO_16MB/mpconfigboard.h
@@ -0,0 +1,28 @@
+// https://shop.pimoroni.com/products/pimoroni-pico-lipo?variant=39335427080275
+
+#define MICROPY_HW_BOARD_NAME          "Pimoroni Pico LiPo 16MB"
+#define MICROPY_HW_FLASH_STORAGE_BYTES (7 * 1024 * 1024)
+
+#define MICROPY_HW_USB_VID (0x2E8A)
+#define MICROPY_HW_USB_PID (0x1003)
+
+#define MICROPY_HW_UART1_TX  (8)
+#define MICROPY_HW_UART1_RX  (9)
+#define MICROPY_HW_UART1_CTS (10)
+#define MICROPY_HW_UART1_RTS (11)
+
+// Qwiic on I2C0
+#define MICROPY_HW_I2C0_SCL  (4)
+#define MICROPY_HW_I2C0_SDA  (5)
+
+#define MICROPY_HW_SPI0_SCK  (18)
+#define MICROPY_HW_SPI0_MOSI (19)
+#define MICROPY_HW_SPI0_MISO (16)
+
+// User LED GPIO25
+
+// VBUS_SENSE GPIO24
+
+// BAT_SENSE GPIO29
+
+// Boot button GPIO23
diff --git a/ports/rp2/boards/PIMORONI_PICOLIPO_4MB/mpconfigboard.cmake b/ports/rp2/boards/PIMORONI_PICOLIPO_4MB/mpconfigboard.cmake
new file mode 100644
index 000000000..8da827a17
--- /dev/null
+++ b/ports/rp2/boards/PIMORONI_PICOLIPO_4MB/mpconfigboard.cmake
@@ -0,0 +1 @@
+# cmake file for Pimoroni Pico LiPo 4MB
diff --git a/ports/rp2/boards/PIMORONI_PICOLIPO_4MB/mpconfigboard.h b/ports/rp2/boards/PIMORONI_PICOLIPO_4MB/mpconfigboard.h
new file mode 100644
index 000000000..fd45547e1
--- /dev/null
+++ b/ports/rp2/boards/PIMORONI_PICOLIPO_4MB/mpconfigboard.h
@@ -0,0 +1,28 @@
+// https://shop.pimoroni.com/products/pimoroni-pico-lipo?variant=39386149093459
+
+#define MICROPY_HW_BOARD_NAME          "Pimoroni Pico LiPo 4MB"
+#define MICROPY_HW_FLASH_STORAGE_BYTES (3 * 1024 * 1024)
+
+#define MICROPY_HW_USB_VID (0x2E8A)
+#define MICROPY_HW_USB_PID (0x1002)
+
+#define MICROPY_HW_UART1_TX  (8)
+#define MICROPY_HW_UART1_RX  (9)
+#define MICROPY_HW_UART1_CTS (10)
+#define MICROPY_HW_UART1_RTS (11)
+
+// Qwiic on I2C0
+#define MICROPY_HW_I2C0_SCL  (4)
+#define MICROPY_HW_I2C0_SDA  (5)
+
+#define MICROPY_HW_SPI0_SCK  (18)
+#define MICROPY_HW_SPI0_MOSI (19)
+#define MICROPY_HW_SPI0_MISO (16)
+
+// User LED GPIO25
+
+// VBUS_SENSE GPIO24
+
+// BAT_SENSE GPIO29
+
+// Boot button GPIO23
diff --git a/ports/rp2/boards/PIMORONI_TINY2040/mpconfigboard.cmake b/ports/rp2/boards/PIMORONI_TINY2040/mpconfigboard.cmake
new file mode 100644
index 000000000..b6c4b3efc
--- /dev/null
+++ b/ports/rp2/boards/PIMORONI_TINY2040/mpconfigboard.cmake
@@ -0,0 +1 @@
+# cmake file for Pimoroni Tiny 2040
diff --git a/ports/rp2/boards/PIMORONI_TINY2040/mpconfigboard.h b/ports/rp2/boards/PIMORONI_TINY2040/mpconfigboard.h
new file mode 100644
index 000000000..50cb2bd59
--- /dev/null
+++ b/ports/rp2/boards/PIMORONI_TINY2040/mpconfigboard.h
@@ -0,0 +1,17 @@
+// https://shop.pimoroni.com/products/tiny-2040
+
+#define MICROPY_HW_BOARD_NAME          "Pimoroni Tiny 2040"
+#define MICROPY_HW_FLASH_STORAGE_BYTES (7 * 1024 * 1024)
+
+#define MICROPY_HW_USB_VID (0x16D0)
+#define MICROPY_HW_USB_PID (0x08C7)
+
+#define MICROPY_HW_I2C0_SCL  (4)
+#define MICROPY_HW_I2C0_SDA  (5)
+
+// RGB LED, active low
+// Red LED 18
+// Green LED 19
+// Blue LED 20
+
+// Boot button GPIO23
diff --git a/ports/rp2/boards/SPARKFUN_PROMICRO/mpconfigboard.h b/ports/rp2/boards/SPARKFUN_PROMICRO/mpconfigboard.h
index d6c8007ba..65b29eecd 100644
--- a/ports/rp2/boards/SPARKFUN_PROMICRO/mpconfigboard.h
+++ b/ports/rp2/boards/SPARKFUN_PROMICRO/mpconfigboard.h
@@ -1,3 +1,22 @@
-// Board and hardware specific configuration
-#define MICROPY_HW_BOARD_NAME                   "SparkFun Pro Micro RP2040"
-#define MICROPY_HW_FLASH_STORAGE_BYTES          (15 * 1024 * 1024)
+// https://www.sparkfun.com/products/17717
+
+#define MICROPY_HW_BOARD_NAME          "SparkFun Pro Micro RP2040"
+#define MICROPY_HW_FLASH_STORAGE_BYTES (15 * 1024 * 1024)
+
+#define MICROPY_HW_USB_VID (0x1B4F)
+#define MICROPY_HW_USB_PID (0x0026)
+
+#define MICROPY_HW_UART1_TX  (8)
+#define MICROPY_HW_UART1_RX  (9)
+#define MICROPY_HW_UART1_CTS (10)
+#define MICROPY_HW_UART1_RTS (11)
+
+// Qwiic on I2C0
+#define MICROPY_HW_I2C0_SCL  (17)
+#define MICROPY_HW_I2C0_SDA  (16)
+
+#define MICROPY_HW_SPI0_SCK  (22)
+#define MICROPY_HW_SPI0_MOSI (23)
+#define MICROPY_HW_SPI0_MISO (20)
+
+// NeoPixel data GPIO25, power not toggleable
diff --git a/ports/rp2/boards/SPARKFUN_THINGPLUS/mpconfigboard.h b/ports/rp2/boards/SPARKFUN_THINGPLUS/mpconfigboard.h
index 9749acd25..f88ba5dd6 100644
--- a/ports/rp2/boards/SPARKFUN_THINGPLUS/mpconfigboard.h
+++ b/ports/rp2/boards/SPARKFUN_THINGPLUS/mpconfigboard.h
@@ -1,3 +1,31 @@
-// Board and hardware specific configuration
-#define MICROPY_HW_BOARD_NAME                   "SparkFun Thing Plus RP2040"
-#define MICROPY_HW_FLASH_STORAGE_BYTES          (15 * 1024 * 1024)
+// https://www.sparkfun.com/products/17745
+
+#define MICROPY_HW_BOARD_NAME          "SparkFun Thing Plus RP2040"
+#define MICROPY_HW_FLASH_STORAGE_BYTES (15 * 1024 * 1024)
+
+#define MICROPY_HW_USB_VID (0x1B4F)
+#define MICROPY_HW_USB_PID (0x0025)
+
+#define MICROPY_HW_I2C0_SCL  (17)
+#define MICROPY_HW_I2C0_SDA  (16)
+
+// Qwiic on I2C1
+#define MICROPY_HW_I2C1_SCL  (7)
+#define MICROPY_HW_I2C1_SDA  (6)
+
+#define MICROPY_HW_SPI0_SCK  (2)
+#define MICROPY_HW_SPI0_MOSI (3)
+#define MICROPY_HW_SPI0_MISO (4)
+
+// MicroSD on SPI1
+#define MICROPY_HW_SPI1_SCK  (14)
+#define MICROPY_HW_SPI1_MOSI (15)
+#define MICROPY_HW_SPI1_MISO (12)
+
+// Battery fuel guage MAX17048 on I2C1
+// BATT_ALERT GPIO24
+
+// NeoPixel data GPIO8, power not toggleable
+// data out is broken out to a pin
+
+// Blue user LED GPIO25
diff --git a/ports/rp2/machine_i2c.c b/ports/rp2/machine_i2c.c
index 0852cc199..3b895ba4d 100644
--- a/ports/rp2/machine_i2c.c
+++ b/ports/rp2/machine_i2c.c
@@ -33,10 +33,16 @@
 #include "hardware/i2c.h"
 
 #define DEFAULT_I2C_FREQ (400000)
-#define DEFAULT_I2C0_SCL (9)
-#define DEFAULT_I2C0_SDA (8)
-#define DEFAULT_I2C1_SCL (7)
-#define DEFAULT_I2C1_SDA (6)
+
+#ifndef MICROPY_HW_I2C0_SCL
+#define MICROPY_HW_I2C0_SCL (9)
+#define MICROPY_HW_I2C0_SDA (8)
+#endif
+
+#ifndef MICROPY_HW_I2C1_SCL
+#define MICROPY_HW_I2C1_SCL (7)
+#define MICROPY_HW_I2C1_SDA (6)
+#endif
 
 // SDA/SCL on even/odd pins, I2C0/I2C1 on even/odd pairs of pins.
 #define IS_VALID_SCL(i2c, pin) (((pin) & 1) == 1 && (((pin) & 2) >> 1) == (i2c))
@@ -52,8 +58,8 @@ typedef struct _machine_i2c_obj_t {
 } machine_i2c_obj_t;
 
 STATIC machine_i2c_obj_t machine_i2c_obj[] = {
-    {{&machine_hw_i2c_type}, i2c0, 0, DEFAULT_I2C0_SCL, DEFAULT_I2C0_SDA, 0},
-    {{&machine_hw_i2c_type}, i2c1, 1, DEFAULT_I2C1_SCL, DEFAULT_I2C1_SDA, 0},
+    {{&machine_hw_i2c_type}, i2c0, 0, MICROPY_HW_I2C0_SCL, MICROPY_HW_I2C0_SDA, 0},
+    {{&machine_hw_i2c_type}, i2c1, 1, MICROPY_HW_I2C1_SCL, MICROPY_HW_I2C1_SDA, 0},
 };
 
 STATIC void machine_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
diff --git a/ports/rp2/machine_pin.c b/ports/rp2/machine_pin.c
index 0525e0f9f..aa3cad6ef 100644
--- a/ports/rp2/machine_pin.c
+++ b/ports/rp2/machine_pin.c
@@ -29,7 +29,7 @@
 
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/mpirq.h"
 #include "modmachine.h"
 #include "extmod/virtpin.h"
 
diff --git a/ports/rp2/machine_rtc.c b/ports/rp2/machine_rtc.c
index a7c55b616..9d59124a6 100644
--- a/ports/rp2/machine_rtc.c
+++ b/ports/rp2/machine_rtc.c
@@ -35,7 +35,7 @@
 #include "py/runtime.h"
 #include "py/mphal.h"
 #include "py/mperrno.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "hardware/rtc.h"
 #include "pico/util/datetime.h"
 #include "modmachine.h"
diff --git a/ports/rp2/machine_spi.c b/ports/rp2/machine_spi.c
index 478c06145..332f44694 100644
--- a/ports/rp2/machine_spi.c
+++ b/ports/rp2/machine_spi.c
@@ -38,12 +38,18 @@
 #define DEFAULT_SPI_PHASE       (0)
 #define DEFAULT_SPI_BITS        (8)
 #define DEFAULT_SPI_FIRSTBIT    (SPI_MSB_FIRST)
-#define DEFAULT_SPI0_SCK        (6)
-#define DEFAULT_SPI0_MOSI       (7)
-#define DEFAULT_SPI0_MISO       (4)
-#define DEFAULT_SPI1_SCK        (10)
-#define DEFAULT_SPI1_MOSI       (11)
-#define DEFAULT_SPI1_MISO       (8)
+
+#ifndef MICROPY_HW_SPI0_SCK
+#define MICROPY_HW_SPI0_SCK     (6)
+#define MICROPY_HW_SPI0_MOSI    (7)
+#define MICROPY_HW_SPI0_MISO    (4)
+#endif
+
+#ifndef MICROPY_HW_SPI1_SCK
+#define MICROPY_HW_SPI1_SCK     (10)
+#define MICROPY_HW_SPI1_MOSI    (11)
+#define MICROPY_HW_SPI1_MISO    (8)
+#endif
 
 #define IS_VALID_PERIPH(spi, pin)   ((((pin) & 8) >> 3) == (spi))
 #define IS_VALID_SCK(spi, pin)      (((pin) & 3) == 2 && IS_VALID_PERIPH(spi, pin))
@@ -68,13 +74,13 @@ STATIC machine_spi_obj_t machine_spi_obj[] = {
     {
         {&machine_spi_type}, spi0, 0,
         DEFAULT_SPI_POLARITY, DEFAULT_SPI_PHASE, DEFAULT_SPI_BITS, DEFAULT_SPI_FIRSTBIT,
-        DEFAULT_SPI0_SCK, DEFAULT_SPI0_MOSI, DEFAULT_SPI0_MISO,
+        MICROPY_HW_SPI0_SCK, MICROPY_HW_SPI0_MOSI, MICROPY_HW_SPI0_MISO,
         0,
     },
     {
         {&machine_spi_type}, spi1, 1,
         DEFAULT_SPI_POLARITY, DEFAULT_SPI_PHASE, DEFAULT_SPI_BITS, DEFAULT_SPI_FIRSTBIT,
-        DEFAULT_SPI1_SCK, DEFAULT_SPI1_MOSI, DEFAULT_SPI1_MISO,
+        MICROPY_HW_SPI1_SCK, MICROPY_HW_SPI1_MOSI, MICROPY_HW_SPI1_MISO,
         0,
     },
 };
diff --git a/ports/rp2/machine_uart.c b/ports/rp2/machine_uart.c
index 2da3ab41f..a8ec149f4 100644
--- a/ports/rp2/machine_uart.c
+++ b/ports/rp2/machine_uart.c
@@ -38,10 +38,23 @@
 #define DEFAULT_UART_BAUDRATE (115200)
 #define DEFAULT_UART_BITS (8)
 #define DEFAULT_UART_STOP (1)
-#define DEFAULT_UART0_TX (0)
-#define DEFAULT_UART0_RX (1)
-#define DEFAULT_UART1_TX (4)
-#define DEFAULT_UART1_RX (5)
+
+// UART 0 default pins
+#if !defined(MICROPY_HW_UART0_TX)
+#define MICROPY_HW_UART0_TX (0)
+#define MICROPY_HW_UART0_RX (1)
+#define MICROPY_HW_UART0_CTS (2)
+#define MICROPY_HW_UART0_RTS (3)
+#endif
+
+// UART 1 default pins
+#if !defined(MICROPY_HW_UART1_TX)
+#define MICROPY_HW_UART1_TX (4)
+#define MICROPY_HW_UART1_RX (5)
+#define MICROPY_HW_UART1_CTS (6)
+#define MICROPY_HW_UART1_RTS (7)
+#endif
+
 #define DEFAULT_BUFFER_SIZE (256)
 #define MIN_BUFFER_SIZE  (32)
 #define MAX_BUFFER_SIZE  (32766)
@@ -49,11 +62,16 @@
 #define IS_VALID_PERIPH(uart, pin)  (((((pin) + 4) & 8) >> 3) == (uart))
 #define IS_VALID_TX(uart, pin)      (((pin) & 3) == 0 && IS_VALID_PERIPH(uart, pin))
 #define IS_VALID_RX(uart, pin)      (((pin) & 3) == 1 && IS_VALID_PERIPH(uart, pin))
+#define IS_VALID_CTS(uart, pin)     (((pin) & 3) == 2 && IS_VALID_PERIPH(uart, pin))
+#define IS_VALID_RTS(uart, pin)     (((pin) & 3) == 3 && IS_VALID_PERIPH(uart, pin))
 
 #define UART_INVERT_TX (1)
 #define UART_INVERT_RX (2)
 #define UART_INVERT_MASK (UART_INVERT_TX | UART_INVERT_RX)
 
+#define UART_HWCONTROL_CTS  (1)
+#define UART_HWCONTROL_RTS  (2)
+
 typedef struct _machine_uart_obj_t {
     mp_obj_base_t base;
     uart_inst_t *const uart;
@@ -64,9 +82,12 @@ typedef struct _machine_uart_obj_t {
     uint8_t stop;
     uint8_t tx;
     uint8_t rx;
+    uint8_t cts;
+    uint8_t rts;
     uint16_t timeout;       // timeout waiting for first char (in ms)
     uint16_t timeout_char;  // timeout waiting between chars (in ms)
     uint8_t invert;
+    uint8_t flow;
     ringbuf_t read_buffer;
     bool read_lock;
     ringbuf_t write_buffer;
@@ -75,9 +96,11 @@ typedef struct _machine_uart_obj_t {
 
 STATIC machine_uart_obj_t machine_uart_obj[] = {
     {{&machine_uart_type}, uart0, 0, 0, DEFAULT_UART_BITS, UART_PARITY_NONE, DEFAULT_UART_STOP,
-     DEFAULT_UART0_TX, DEFAULT_UART0_RX, 0, 0, 0, {NULL, 1, 0, 0}, 0, {NULL, 1, 0, 0}, 0},
+     MICROPY_HW_UART0_TX, MICROPY_HW_UART0_RX, MICROPY_HW_UART0_CTS, MICROPY_HW_UART0_RTS,
+     0, 0, 0, 0, {NULL, 1, 0, 0}, 0, {NULL, 1, 0, 0}, 0},
     {{&machine_uart_type}, uart1, 1, 0, DEFAULT_UART_BITS, UART_PARITY_NONE, DEFAULT_UART_STOP,
-     DEFAULT_UART1_TX, DEFAULT_UART1_RX, 0, 0, 0, {NULL, 1, 0, 0}, 0, {NULL, 1, 0, 0}, 0,},
+     MICROPY_HW_UART1_TX, MICROPY_HW_UART1_RX, MICROPY_HW_UART1_CTS, MICROPY_HW_UART1_RTS,
+     0, 0, 0, 0, {NULL, 1, 0, 0}, 0, {NULL, 1, 0, 0}, 0},
 };
 
 STATIC const char *_parity_name[] = {"None", "0", "1"};
@@ -140,8 +163,8 @@ STATIC void machine_uart_print(const mp_print_t *print, mp_obj_t self_in, mp_pri
 }
 
 STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
-    enum { ARG_id, ARG_baudrate, ARG_bits, ARG_parity, ARG_stop, ARG_tx, ARG_rx,
-           ARG_timeout, ARG_timeout_char, ARG_invert, ARG_txbuf, ARG_rxbuf};
+    enum { ARG_id, ARG_baudrate, ARG_bits, ARG_parity, ARG_stop, ARG_tx, ARG_rx, ARG_cts, ARG_rts,
+           ARG_timeout, ARG_timeout_char, ARG_invert, ARG_flow, ARG_txbuf, ARG_rxbuf};
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
         { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = -1} },
@@ -150,9 +173,12 @@ STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args,
         { MP_QSTR_stop, MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_tx, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
         { MP_QSTR_rx, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_cts, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_rts, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
         { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_timeout_char, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_invert, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_flow, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_txbuf, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_rxbuf, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
     };
@@ -212,6 +238,22 @@ STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args,
         self->rx = rx;
     }
 
+    // Set CTS/RTS pins if configured.
+    if (args[ARG_cts].u_obj != mp_const_none) {
+        int cts = mp_hal_get_pin_obj(args[ARG_cts].u_obj);
+        if (!IS_VALID_CTS(self->uart_id, cts)) {
+            mp_raise_ValueError(MP_ERROR_TEXT("bad CTS pin"));
+        }
+        self->cts = cts;
+    }
+    if (args[ARG_rts].u_obj != mp_const_none) {
+        int rts = mp_hal_get_pin_obj(args[ARG_rts].u_obj);
+        if (!IS_VALID_RTS(self->uart_id, rts)) {
+            mp_raise_ValueError(MP_ERROR_TEXT("bad RTS pin"));
+        }
+        self->rts = rts;
+    }
+
     // Set timeout if configured.
     if (args[ARG_timeout].u_int >= 0) {
         self->timeout = args[ARG_timeout].u_int;
@@ -230,6 +272,14 @@ STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args,
         self->invert = args[ARG_invert].u_int;
     }
 
+    // Set hardware flow control if configured.
+    if (args[ARG_flow].u_int >= 0) {
+        if (args[ARG_flow].u_int & ~(UART_HWCONTROL_CTS | UART_HWCONTROL_RTS)) {
+            mp_raise_ValueError(MP_ERROR_TEXT("bad hardware flow control mask"));
+        }
+        self->flow = args[ARG_flow].u_int;
+    }
+
     self->read_lock = false;
 
     // Set the RX buffer size if configured.
@@ -278,6 +328,15 @@ STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args,
             gpio_set_outover(self->tx, GPIO_OVERRIDE_INVERT);
         }
 
+        // Set hardware flow control if configured.
+        if (self->flow & UART_HWCONTROL_CTS) {
+            gpio_set_function(self->cts, GPIO_FUNC_UART);
+        }
+        if (self->flow & UART_HWCONTROL_RTS) {
+            gpio_set_function(self->rts, GPIO_FUNC_UART);
+        }
+        uart_set_hw_flow(self->uart, self->flow & UART_HWCONTROL_CTS, self->flow & UART_HWCONTROL_RTS);
+
         // Allocate the RX/TX buffers.
         ringbuf_alloc(&(self->read_buffer), rxbuf_len + 1);
         MP_STATE_PORT(rp2_uart_rx_buffer[uart_id]) = self->read_buffer.buf;
@@ -333,6 +392,9 @@ STATIC const mp_rom_map_elem_t machine_uart_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_INV_TX), MP_ROM_INT(UART_INVERT_TX) },
     { MP_ROM_QSTR(MP_QSTR_INV_RX), MP_ROM_INT(UART_INVERT_RX) },
 
+    { MP_ROM_QSTR(MP_QSTR_CTS), MP_ROM_INT(UART_HWCONTROL_CTS) },
+    { MP_ROM_QSTR(MP_QSTR_RTS), MP_ROM_INT(UART_HWCONTROL_RTS) },
+
 };
 STATIC MP_DEFINE_CONST_DICT(machine_uart_locals_dict, machine_uart_locals_dict_table);
 
@@ -345,6 +407,13 @@ STATIC mp_uint_t machine_uart_read(mp_obj_t self_in, void *buf_in, mp_uint_t siz
     for (size_t i = 0; i < size; i++) {
         // Wait for the first/next character
         while (ringbuf_avail(&self->read_buffer) == 0) {
+            if (uart_is_readable(self->uart)) {
+                // Force a few incoming bytes to the buffer
+                self->read_lock = true;
+                uart_drain_rx_fifo(self);
+                self->read_lock = false;
+                break;
+            }
             if (time_us_64() > t) {  // timed out
                 if (i <= 0) {
                     *errcode = MP_EAGAIN;
@@ -354,10 +423,6 @@ STATIC mp_uint_t machine_uart_read(mp_obj_t self_in, void *buf_in, mp_uint_t siz
                 }
             }
             MICROPY_EVENT_POLL_HOOK
-            // Force a few incoming bytes to the buffer
-            self->read_lock = true;
-            uart_drain_rx_fifo(self);
-            self->read_lock = false;
         }
         *dest++ = ringbuf_get(&(self->read_buffer));
         t = time_us_64() + timeout_char_us;
@@ -415,7 +480,7 @@ STATIC mp_uint_t machine_uart_ioctl(mp_obj_t self_in, mp_uint_t request, mp_uint
     if (request == MP_STREAM_POLL) {
         uintptr_t flags = arg;
         ret = 0;
-        if ((flags & MP_STREAM_POLL_RD) && ringbuf_avail(&self->read_buffer) > 0) {
+        if ((flags & MP_STREAM_POLL_RD) && (uart_is_readable(self->uart) || ringbuf_avail(&self->read_buffer) > 0)) {
             ret |= MP_STREAM_POLL_RD;
         }
         if ((flags & MP_STREAM_POLL_WR) && ringbuf_free(&self->write_buffer) > 0) {
diff --git a/ports/rp2/main.c b/ports/rp2/main.c
index 8c5772171..d0b89c8d6 100644
--- a/ports/rp2/main.c
+++ b/ports/rp2/main.c
@@ -32,9 +32,9 @@
 #include "py/mperrno.h"
 #include "py/mphal.h"
 #include "py/stackctrl.h"
-#include "lib/mp-readline/readline.h"
-#include "lib/utils/gchelper.h"
-#include "lib/utils/pyexec.h"
+#include "shared/readline/readline.h"
+#include "shared/runtime/gchelper.h"
+#include "shared/runtime/pyexec.h"
 #include "tusb.h"
 #include "uart.h"
 #include "modmachine.h"
@@ -227,4 +227,3 @@ const char rp2_help_text[] =
     "For further help on a specific object, type help(obj)\n"
     "For a list of available modules, type help('modules')\n"
 ;
-
diff --git a/ports/rp2/modmachine.c b/ports/rp2/modmachine.c
index 3656a7db5..1b2b2adad 100644
--- a/ports/rp2/modmachine.c
+++ b/ports/rp2/modmachine.c
@@ -26,7 +26,7 @@
 
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 #include "extmod/machine_i2c.h"
 #include "extmod/machine_mem.h"
 #include "extmod/machine_pulse.h"
diff --git a/ports/rp2/modutime.c b/ports/rp2/modutime.c
index 4835a0ee1..8041ae65b 100644
--- a/ports/rp2/modutime.c
+++ b/ports/rp2/modutime.c
@@ -25,7 +25,7 @@
  */
 
 #include "py/runtime.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "extmod/utime_mphal.h"
 #include "hardware/rtc.h"
 
diff --git a/ports/rp2/mpconfigport.h b/ports/rp2/mpconfigport.h
index 85015f3ab..f95d6a470 100644
--- a/ports/rp2/mpconfigport.h
+++ b/ports/rp2/mpconfigport.h
@@ -77,6 +77,7 @@
 #define MICROPY_PY_FUNCTION_ATTRS               (1)
 #define MICROPY_PY_DESCRIPTORS                  (1)
 #define MICROPY_PY_DELATTR_SETATTR              (1)
+#define MICROPY_PY_FSTRINGS                     (1)
 #define MICROPY_PY_BUILTINS_STR_UNICODE         (1)
 #define MICROPY_PY_BUILTINS_STR_CENTER          (1)
 #define MICROPY_PY_BUILTINS_STR_PARTITION       (1)
@@ -203,6 +204,10 @@ extern const struct _mp_obj_module_t mp_module_lodepng;
 #define LV_ROOTS
 #endif
 
+#ifndef MICROPY_BOARD_ROOT_POINTERS
+#define MICROPY_BOARD_ROOT_POINTERS
+#endif
+
 #define MICROPY_PORT_ROOT_POINTERS \
     LV_ROOTS \
     void *mp_lv_user_data; \
@@ -212,6 +217,7 @@ extern const struct _mp_obj_module_t mp_module_lodepng;
     void *rp2_state_machine_irq_obj[8]; \
     void *rp2_uart_rx_buffer[2]; \
     void *rp2_uart_tx_buffer[2]; \
+    MICROPY_BOARD_ROOT_POINTERS \
 
 #define MP_STATE_PORT MP_STATE_VM
 
diff --git a/ports/rp2/mphalport.c b/ports/rp2/mphalport.c
index 1d77bc8f5..3385323db 100644
--- a/ports/rp2/mphalport.c
+++ b/ports/rp2/mphalport.c
@@ -27,7 +27,7 @@
 #include "py/runtime.h"
 #include "py/stream.h"
 #include "py/mphal.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "tusb.h"
 #include "uart.h"
 #include "hardware/rtc.h"
diff --git a/ports/rp2/rp2_flash.c b/ports/rp2/rp2_flash.c
index b89cb6fd8..80bc1dc1d 100644
--- a/ports/rp2/rp2_flash.c
+++ b/ports/rp2/rp2_flash.c
@@ -95,12 +95,20 @@ STATIC mp_obj_t rp2_flash_writeblocks(size_t n_args, const mp_obj_t *args) {
     mp_buffer_info_t bufinfo;
     mp_get_buffer_raise(args[2], &bufinfo, MP_BUFFER_READ);
     if (n_args == 3) {
+        // Flash erase/program must run in an atomic section because the XIP bit gets disabled.
+        mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
         flash_range_erase(self->flash_base + offset, bufinfo.len);
+        MICROPY_END_ATOMIC_SECTION(atomic_state);
+        MICROPY_EVENT_POLL_HOOK
         // TODO check return value
     } else {
         offset += mp_obj_get_int(args[3]);
     }
+    // Flash erase/program must run in an atomic section because the XIP bit gets disabled.
+    mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
     flash_range_program(self->flash_base + offset, bufinfo.buf, bufinfo.len);
+    MICROPY_END_ATOMIC_SECTION(atomic_state);
+    MICROPY_EVENT_POLL_HOOK
     // TODO check return value
     return mp_const_none;
 }
@@ -122,7 +130,10 @@ STATIC mp_obj_t rp2_flash_ioctl(mp_obj_t self_in, mp_obj_t cmd_in, mp_obj_t arg_
             return MP_OBJ_NEW_SMALL_INT(BLOCK_SIZE_BYTES);
         case MP_BLOCKDEV_IOCTL_BLOCK_ERASE: {
             uint32_t offset = mp_obj_get_int(arg_in) * BLOCK_SIZE_BYTES;
+            // Flash erase/program must run in an atomic section because the XIP bit gets disabled.
+            mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
             flash_range_erase(self->flash_base + offset, BLOCK_SIZE_BYTES);
+            MICROPY_END_ATOMIC_SECTION(atomic_state);
             // TODO check return value
             return MP_OBJ_NEW_SMALL_INT(0);
         }
diff --git a/ports/rp2/rp2_pio.c b/ports/rp2/rp2_pio.c
index 44928c0a8..414fa8bd7 100644
--- a/ports/rp2/rp2_pio.c
+++ b/ports/rp2/rp2_pio.c
@@ -30,7 +30,7 @@
 #include "py/runtime.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/mpirq.h"
 #include "modrp2.h"
 
 #include "hardware/clocks.h"
diff --git a/ports/rp2/tusb_config.h b/ports/rp2/tusb_config.h
index 1402edf37..8c2a9f756 100644
--- a/ports/rp2/tusb_config.h
+++ b/ports/rp2/tusb_config.h
@@ -28,6 +28,7 @@
 #define CFG_TUSB_RHPORT0_MODE   (OPT_MODE_DEVICE)
 
 #define CFG_TUD_CDC             (1)
+#define CFG_TUD_CDC_EP_BUFSIZE  (256)
 #define CFG_TUD_CDC_RX_BUFSIZE  (256)
 #define CFG_TUD_CDC_TX_BUFSIZE  (256)
 
diff --git a/ports/rp2/tusb_port.c b/ports/rp2/tusb_port.c
index 874d837b9..8896be907 100644
--- a/ports/rp2/tusb_port.c
+++ b/ports/rp2/tusb_port.c
@@ -27,8 +27,12 @@
 #include "tusb.h"
 #include "pico/unique_id.h"
 
-#define USBD_VID (0x2E8A) // Raspberry Pi
-#define USBD_PID (0x0005) // RP2 MicroPython
+#ifndef MICROPY_HW_USB_VID
+#define MICROPY_HW_USB_VID (0x2E8A) // Raspberry Pi
+#endif
+#ifndef MICROPY_HW_USB_PID
+#define MICROPY_HW_USB_PID (0x0005) // RP2 MicroPython
+#endif
 
 #define USBD_DESC_LEN (TUD_CONFIG_DESC_LEN + TUD_CDC_DESC_LEN)
 #define USBD_MAX_POWER_MA (250)
@@ -58,8 +62,8 @@ static const tusb_desc_device_t usbd_desc_device = {
     .bDeviceSubClass = MISC_SUBCLASS_COMMON,
     .bDeviceProtocol = MISC_PROTOCOL_IAD,
     .bMaxPacketSize0 = CFG_TUD_ENDPOINT0_SIZE,
-    .idVendor = USBD_VID,
-    .idProduct = USBD_PID,
+    .idVendor = MICROPY_HW_USB_VID,
+    .idProduct = MICROPY_HW_USB_PID,
     .bcdDevice = 0x0100,
     .iManufacturer = USBD_STR_MANUF,
     .iProduct = USBD_STR_PRODUCT,
diff --git a/ports/samd/Makefile b/ports/samd/Makefile
index ffd0f06a3..a84fc3b12 100644
--- a/ports/samd/Makefile
+++ b/ports/samd/Makefile
@@ -33,7 +33,11 @@ CFLAGS_MCU_SAMD21 = -mtune=cortex-m0plus -mcpu=cortex-m0plus -msoft-float
 CFLAGS_MCU_SAMD51 = -mtune=cortex-m4 -mcpu=cortex-m4 -mfpu=fpv4-sp-d16 -mfloat-abi=hard
 CFLAGS = $(INC) -Wall -Werror -std=c99 -nostdlib -mthumb $(CFLAGS_MCU_$(MCU_SERIES)) -fsingle-precision-constant -Wdouble-promotion
 CFLAGS += -DMCU_$(MCU_SERIES) -D__$(CMSIS_MCU)__
+CFLAGS += $(CFLAGS_MOD)
+
 LDFLAGS = -nostdlib $(addprefix -T,$(LD_FILES)) -Map=$@.map --cref
+LDFLAGS += $(LDFLAGS_MOD)
+
 LIBS = $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)
 
 # Tune for Debugging or Optimization
@@ -45,6 +49,14 @@ LDFLAGS += --gc-sections
 CFLAGS += -fdata-sections -ffunction-sections
 endif
 
+# Flags for optional C++ source code
+CXXFLAGS += $(filter-out -std=c99,$(CFLAGS))
+CXXFLAGS += $(CXXFLAGS_MOD)
+ifneq ($(SRC_CXX)$(SRC_MOD_CXX),)
+LIBSTDCPP_FILE_NAME = "$(shell $(CXX) $(CXXFLAGS) -print-file-name=libstdc++.a)"
+LDFLAGS += -L"$(shell dirname $(LIBSTDCPP_FILE_NAME))"
+endif
+
 SRC_C = \
 	main.c \
 	modutime.c \
@@ -53,34 +65,39 @@ SRC_C = \
 	samd_isr.c \
 	samd_soc.c \
 	tusb_port.c \
-	lib/libc/string0.c \
 	lib/libm/ef_sqrt.c \
 	lib/libm/fmodf.c \
 	lib/libm/math.c \
 	lib/libm/nearbyintf.c \
-	lib/mp-readline/readline.c \
 	lib/tinyusb/src/class/cdc/cdc_device.c \
 	lib/tinyusb/src/common/tusb_fifo.c \
 	lib/tinyusb/src/device/usbd.c \
 	lib/tinyusb/src/device/usbd_control.c \
 	lib/tinyusb/src/portable/microchip/samd/dcd_samd.c \
 	lib/tinyusb/src/tusb.c \
-	lib/utils/gchelper_native.c \
-	lib/utils/printf.c \
-	lib/utils/pyexec.c \
-	lib/utils/stdout_helpers.c \
+	shared/libc/printf.c \
+	shared/libc/string0.c \
+	shared/readline/readline.c \
+	shared/runtime/gchelper_native.c \
+	shared/runtime/pyexec.c \
+	shared/runtime/stdout_helpers.c \
+
+SRC_C += $(SRC_MOD)
+
+SRC_CXX += $(SRC_MOD_CXX)
 
 ifeq ($(MCU_SERIES),SAMD21)
-SRC_S = lib/utils/gchelper_m0.s
+SRC_S = shared/runtime/gchelper_m0.s
 else
-SRC_S = lib/utils/gchelper_m3.s
+SRC_S = shared/runtime/gchelper_m3.s
 endif
 
 # List of sources for qstr extraction
-SRC_QSTR += modutime.c modmachine.c
+SRC_QSTR += modutime.c modmachine.c $(SRC_MOD) $(SRC_CXX)
 
 OBJ += $(PY_O)
 OBJ += $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
+OBJ += $(addprefix $(BUILD)/, $(SRC_CXX:.cpp=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_S:.s=.o))
 
 # Workaround for bug in older gcc, warning on "static usbd_device_t _usbd_dev = { 0 };"
diff --git a/ports/samd/main.c b/ports/samd/main.c
index 038373ceb..5d84a9e88 100644
--- a/ports/samd/main.c
+++ b/ports/samd/main.c
@@ -29,8 +29,8 @@
 #include "py/gc.h"
 #include "py/mperrno.h"
 #include "py/stackctrl.h"
-#include "lib/utils/gchelper.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/gchelper.h"
+#include "shared/runtime/pyexec.h"
 
 extern uint8_t _sstack, _estack, _sheap, _eheap;
 
@@ -87,6 +87,11 @@ void nlr_jump_fail(void *val) {
     }
 }
 
+void abort(void) {
+    for (;;) {
+    }
+}
+
 #ifndef NDEBUG
 void MP_WEAK __assert_func(const char *file, int line, const char *func, const char *expr) {
     mp_printf(MP_PYTHON_PRINTER, "Assertion '%s' failed, at file %s:%d\n", expr, file, line);
diff --git a/ports/samd/sections.ld b/ports/samd/sections.ld
index cbcad463d..743e70a30 100644
--- a/ports/samd/sections.ld
+++ b/ports/samd/sections.ld
@@ -11,10 +11,20 @@ SECTIONS
         *(.rodata*)
         . = ALIGN(4);
         _etext = .;
-        _sidata = _etext;
     } >FLASH
 
-    .data : AT ( _sidata )
+    /* For C++ exception handling */
+    .ARM :
+    {
+        __exidx_start = .;
+        *(.ARM.exidx*)
+        __exidx_end = .;
+    } >FLASH
+
+    /* Used by the start-up code to initialise data */
+    _sidata = LOADADDR(.data);
+
+    .data :
     {
         . = ALIGN(4);
         _sdata = .;
@@ -22,7 +32,7 @@ SECTIONS
         *(.data*)
         . = ALIGN(4);
         _edata = .;
-    } >RAM
+    } >RAM AT> FLASH
 
     .bss :
     {
diff --git a/ports/samd/tusb_port.c b/ports/samd/tusb_port.c
index e96f33246..2098334fb 100644
--- a/ports/samd/tusb_port.c
+++ b/ports/samd/tusb_port.c
@@ -27,8 +27,10 @@
 #include "samd_soc.h"
 #include "tusb.h"
 
-#define USBD_VID (0xf055)
-#define USBD_PID (0x9802)
+#ifndef MICROPY_HW_USB_VID
+#define MICROPY_HW_USB_VID (0xf055)
+#define MICROPY_HW_USB_PID (0x9802)
+#endif
 
 #define USBD_DESC_LEN (TUD_CONFIG_DESC_LEN + TUD_CDC_DESC_LEN)
 #define USBD_MAX_POWER_MA (250)
@@ -58,8 +60,8 @@ static const tusb_desc_device_t usbd_desc_device = {
     .bDeviceSubClass = MISC_SUBCLASS_COMMON,
     .bDeviceProtocol = MISC_PROTOCOL_IAD,
     .bMaxPacketSize0 = CFG_TUD_ENDOINT0_SIZE,
-    .idVendor = USBD_VID,
-    .idProduct = USBD_PID,
+    .idVendor = MICROPY_HW_USB_VID,
+    .idProduct = MICROPY_HW_USB_PID,
     .bcdDevice = 0x0100,
     .iManufacturer = USBD_STR_MANUF,
     .iProduct = USBD_STR_PRODUCT,
diff --git a/ports/stm32/Makefile b/ports/stm32/Makefile
index 3725fff52..8ec130380 100644
--- a/ports/stm32/Makefile
+++ b/ports/stm32/Makefile
@@ -34,7 +34,7 @@ MBOOT_TEXT0_ADDR ?= 0x08000000
 # include py core make definitions
 include $(TOP)/py/py.mk
 
-GIT_SUBMODULES = lib/libhydrogen lib/lwip lib/mbedtls lib/mynewt-nimble lib/stm32lib
+GIT_SUBMODULES += lib/libhydrogen lib/lwip lib/mbedtls lib/stm32lib
 
 MCU_SERIES_UPPER = $(shell echo $(MCU_SERIES) | tr '[:lower:]' '[:upper:]')
 CMSIS_MCU_LOWER = $(shell echo $(CMSIS_MCU) | tr '[:upper:]' '[:lower:]')
@@ -100,7 +100,7 @@ CFLAGS_MCU_h7 = $(CFLAGS_CORTEX_M) -mtune=cortex-m7 -mcpu=cortex-m7
 CFLAGS_MCU_wb = $(CFLAGS_CORTEX_M) -mtune=cortex-m4 -mcpu=cortex-m4
 
 CFLAGS += $(INC) -Wall -Wpointer-arith -Wno-error=format -Werror -Wdouble-promotion -Wfloat-conversion -std=gnu99 -nostdlib $(CFLAGS_MOD) $(CFLAGS_EXTRA)
-CFLAGS += -D$(CMSIS_MCU)
+CFLAGS += -D$(CMSIS_MCU) -DUSE_FULL_LL_DRIVER
 CFLAGS += $(CFLAGS_MCU_$(MCU_SERIES))
 CFLAGS += $(COPT)
 CFLAGS += -I$(BOARD_DIR)
@@ -130,7 +130,7 @@ endif
 
 LDFLAGS = -nostdlib -L $(LD_DIR) $(addprefix -T,$(LD_FILES)) -Map=$(@:.elf=.map) --cref
 LDFLAGS += --defsym=_estack_reserve=8
-LIBS = "$(shell $(CC) $(CFLAGS) -print-libgcc-file-name)"
+LIBS += "$(shell $(CC) $(CFLAGS) -print-libgcc-file-name)"
 
 # Remove uncalled code from the final image.
 CFLAGS += -fdata-sections -ffunction-sections
@@ -157,18 +157,19 @@ endif
 # Options for mpy-cross
 MPY_CROSS_FLAGS += -march=armv7m
 
-LIB_SRC_C += $(addprefix lib/,\
+SHARED_SRC_C += $(addprefix shared/,\
 	libc/string0.c \
-	mp-readline/readline.c \
+	netutils/dhcpserver.c \
 	netutils/netutils.c \
 	netutils/trace.c \
-	netutils/dhcpserver.c \
+	readline/readline.c \
+	runtime/gchelper_native.c \
+	runtime/interrupt_char.c \
+	runtime/mpirq.c \
+	runtime/pyexec.c \
+	runtime/stdout_helpers.c \
+	runtime/sys_stdio_mphal.c \
 	timeutils/timeutils.c \
-	utils/gchelper_native.c \
-	utils/pyexec.c \
-	utils/interrupt_char.c \
-	utils/sys_stdio_mphal.c \
-	utils/mpirq.c \
 	)
 
 ifeq ($(MICROPY_FLOAT_IMPL),double)
@@ -317,7 +318,9 @@ SRC_C += \
 	gccollect.c \
 	help.c \
 	machine_adc.c \
+	machine_bitstream.c \
 	machine_i2c.c \
+	machine_i2s.c \
 	machine_spi.c \
 	machine_timer.c \
 	machine_uart.c \
@@ -357,18 +360,18 @@ SRC_O += \
 ifeq ($(MCU_SERIES),f0)
 SRC_O += \
 	resethandler_m0.o \
-	lib/utils/gchelper_m0.o
+	shared/runtime/gchelper_m0.o
 else
 ifeq ($(MCU_SERIES),l0)
 CSUPEROPT = -Os # save some code space
 SRC_O += \
 	resethandler_m0.o \
-	lib/utils/gchelper_m0.o
+	shared/runtime/gchelper_m0.o
 else
 SRC_O += \
 	system_stm32.o \
 	resethandler.o \
-	lib/utils/gchelper_m3.o
+	shared/runtime/gchelper_m3.o
 endif
 endif
 
@@ -396,6 +399,7 @@ HAL_SRC_C += $(addprefix $(HAL_DIR)/Src/stm32$(MCU_SERIES)xx_,\
 	hal_tim_ex.c \
 	hal_uart.c \
 	hal_ltdc.c \
+	ll_utils.c \
 	)
 
 ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),f4 f7 h7 l0 l4 wb))
@@ -429,6 +433,18 @@ ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),f0 f4 f7 h7 l4))
 endif
 endif
 
+ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),f0 f4 f7 l0))
+HAL_SRC_C += $(addprefix $(HAL_DIR)/Src/stm32$(MCU_SERIES)xx_,\
+	hal_i2s.c \
+	)
+endif
+
+ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),f4))
+HAL_SRC_C += $(addprefix $(HAL_DIR)/Src/stm32$(MCU_SERIES)xx_,\
+	hal_i2s_ex.c \
+	)
+endif
+
 USBDEV_SRC_C += $(addprefix $(USBDEV_DIR)/,\
 	core/src/usbd_core.c \
 	core/src/usbd_ctlreq.c \
@@ -510,12 +526,14 @@ endif
 endif
 
 ifeq ($(MICROPY_BLUETOOTH_NIMBLE),1)
+GIT_SUBMODULES += lib/mynewt-nimble
 CFLAGS_MOD += -DMICROPY_PY_BLUETOOTH_ENABLE_L2CAP_CHANNELS=1
 include $(TOP)/extmod/nimble/nimble.mk
 SRC_C += mpnimbleport.c
 endif
 
 ifeq ($(MICROPY_BLUETOOTH_BTSTACK),1)
+GIT_SUBMODULES += lib/btstack
 MICROPY_BLUETOOTH_BTSTACK_H4 ?= 1
 include $(TOP)/extmod/btstack/btstack.mk
 SRC_C += mpbtstackport.c
@@ -543,6 +561,7 @@ endif
 OBJ += $(PY_O)
 OBJ += $(addprefix $(BUILD)/, $(LIB_SRC_C:.c=.o))
 OBJ += $(LIBM_O)
+OBJ += $(addprefix $(BUILD)/, $(SHARED_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(EXTMOD_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(DRIVERS_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(HAL_SRC_C:.c=.o))
@@ -556,7 +575,7 @@ OBJ += $(BUILD)/pins_$(BOARD).o
 # This file contains performance critical functions so turn up the optimisation
 # level.  It doesn't add much to the code size and improves performance a bit.
 # Don't use -O3 with this file because gcc tries to optimise memset in terms of itself.
-$(BUILD)/lib/libc/string0.o: COPT += -O2
+$(BUILD)/shared/libc/string0.o: COPT += -O2
 
 # We put several files into the first 16K section with the ISRs.
 # If we compile these using -O0 then it won't fit. So if you really want these
@@ -723,13 +742,13 @@ GEN_PINS_AF_PY = $(BUILD)/pins_af.py
 INSERT_USB_IDS = $(TOP)/tools/insert-usb-ids.py
 FILE2H = $(TOP)/tools/file2h.py
 
-USB_IDS_FILE = usb.h
+USB_IDS_FILE = mpconfigboard_common.h
 CDCINF_TEMPLATE = pybcdc.inf_template
 GEN_CDCINF_FILE = $(HEADER_BUILD)/pybcdc.inf
 GEN_CDCINF_HEADER = $(HEADER_BUILD)/pybcdc_inf.h
 
 # List of sources for qstr extraction
-SRC_QSTR += $(SRC_C) $(SRC_CXX) $(SRC_MOD) $(LIB_SRC_C) $(EXTMOD_SRC_C)
+SRC_QSTR += $(SRC_C) $(SRC_CXX) $(SRC_MOD) $(LIB_SRC_C) $(SHARED_SRC_C) $(EXTMOD_SRC_C)
 # Append any auto-generated sources that are needed by sources listed in
 # SRC_QSTR
 SRC_QSTR_AUTO_DEPS += $(GEN_CDCINF_HEADER)
diff --git a/ports/stm32/README.md b/ports/stm32/README.md
index f2fdb4dd3..6b5f096d7 100644
--- a/ports/stm32/README.md
+++ b/ports/stm32/README.md
@@ -2,11 +2,13 @@ MicroPython port to STM32 MCUs
 ==============================
 
 This directory contains the port of MicroPython to ST's line of STM32
-microcontrollers.  Supported MCU series are: STM32F0, STM32F4, STM32F7 and
-STM32L4.  Parts of the code here utilise the STM32Cube HAL library.
+microcontrollers.  Supported MCU series are: STM32F0, STM32F4, STM32F7,
+STM32H7, STM32L0, STM32L4 and STM32WB.  Parts of the code here utilise the
+STM32Cube HAL library.
 
 The officially supported boards are the line of pyboards: PYBv1.0 and PYBv1.1
-(both with STM32F405), and PYBLITEv1.0 (with STM32F411).  See
+(both with STM32F405), PYBLITEv1.0 (with STM32F411) and PYBD-SFx (with
+STM32F7xx MCUs).  See
 [micropython.org/pyboard](http://www.micropython.org/pyboard/) for further
 details.
 
@@ -40,18 +42,31 @@ see [here](https://launchpad.net/gcc-arm-embedded) for the main GCC ARM
 Embedded page.  The compiler can be changed using the `CROSS_COMPILE` variable
 when invoking `make`.
 
-First the submodules must be obtained using:
+Next, the board to build must be selected.  The default board is PYBV10 but any
+of the names of the subdirectories in the `boards/` directory is a valid board.
+The board name must be passed as the argument to `BOARD=` when invoking `make`.
 
-    $ make submodules
+All boards require certain submodules to be obtained before they can be built.
+The correct set of submodules can be initialised using (with `PYBV11` as an
+example of the selected board):
 
-Then to build for a given board, run:
+    $ make BOARD=PYBV11 submodules
+
+Then to build the board's firmware run:
 
     $ make BOARD=PYBV11
 
-The default board is PYBV10 but any of the names of the subdirectories in the
-`boards/` directory can be passed as the argument to `BOARD=`.  The above command
-should produce binary images in the `build-PYBV11/` subdirectory (or the
-equivalent directory for the board specified).
+The above command should produce binary images in the `build-PYBV11/`
+subdirectory (or the equivalent directory for the board specified).
+
+Note that some boards require the mboot bootloader to be built and deployed
+before flashing the main firmware.  For such boards an information message
+about this will be printed at the end of the main firmware build.  Mboot
+can be built via:
+
+    $ make -C mboot BOARD=STM32F769DISC
+
+For more information about mboot see mboot/README.md.
 
 
 ### Flashing the Firmware using DFU mode
@@ -140,6 +155,11 @@ Accessing the board
 -------------------
 
 Once built and deployed, access the MicroPython REPL (the Python prompt) via USB
-serial or UART, depending on the board.  For the pyboard you can try:
+serial or UART, depending on the board.  There are many ways to do this, one of
+which is via `mpremote` (install it using `pip install mpremote`):
+
+    $ mpremote
+
+Other options are `picocom` and `screen`, for example:
 
     $ picocom /dev/ttyACM0
diff --git a/ports/stm32/adc.c b/ports/stm32/adc.c
index 55dc3083b..09cd3306b 100644
--- a/ports/stm32/adc.c
+++ b/ports/stm32/adc.c
@@ -70,8 +70,6 @@
 
 #if defined(STM32F0)
 
-#define ADC_FIRST_GPIO_CHANNEL  (0)
-#define ADC_LAST_GPIO_CHANNEL   (15)
 #define ADC_SCALE_V             (3.3f)
 #define ADC_CAL_ADDRESS         (0x1ffff7ba)
 #define ADC_CAL1                ((uint16_t *)0x1ffff7b8)
@@ -80,8 +78,6 @@
 
 #elif defined(STM32F4)
 
-#define ADC_FIRST_GPIO_CHANNEL  (0)
-#define ADC_LAST_GPIO_CHANNEL   (15)
 #define ADC_SCALE_V             (3.3f)
 #define ADC_CAL_ADDRESS         (0x1fff7a2a)
 #define ADC_CAL1                ((uint16_t *)(ADC_CAL_ADDRESS + 2))
@@ -90,8 +86,6 @@
 
 #elif defined(STM32F7)
 
-#define ADC_FIRST_GPIO_CHANNEL  (0)
-#define ADC_LAST_GPIO_CHANNEL   (15)
 #define ADC_SCALE_V             (3.3f)
 #if defined(STM32F722xx) || defined(STM32F723xx) || \
     defined(STM32F732xx) || defined(STM32F733xx)
@@ -106,8 +100,6 @@
 
 #elif defined(STM32H7)
 
-#define ADC_FIRST_GPIO_CHANNEL  (0)
-#define ADC_LAST_GPIO_CHANNEL   (16)
 #define ADC_SCALE_V             (3.3f)
 #define ADC_CAL_ADDRESS         (0x1FF1E860)
 #define ADC_CAL1                ((uint16_t *)(0x1FF1E820))
@@ -116,8 +108,6 @@
 
 #elif defined(STM32L4) || defined(STM32WB)
 
-#define ADC_FIRST_GPIO_CHANNEL  (1)
-#define ADC_LAST_GPIO_CHANNEL   (16)
 #define ADC_SCALE_V             (VREFINT_CAL_VREF / 1000.0f)
 #define ADC_CAL_ADDRESS         (VREFINT_CAL_ADDR)
 #define ADC_CAL1                (TEMPSENSOR_CAL1_ADDR)
@@ -179,7 +169,7 @@
 typedef struct _pyb_obj_adc_t {
     mp_obj_base_t base;
     mp_obj_t pin_name;
-    int channel;
+    uint32_t channel;
     ADC_HandleTypeDef handle;
 } pyb_obj_adc_t;
 
@@ -308,13 +298,6 @@ STATIC void adcx_init_periph(ADC_HandleTypeDef *adch, uint32_t resolution) {
 }
 
 STATIC void adc_init_single(pyb_obj_adc_t *adc_obj) {
-
-    if (ADC_FIRST_GPIO_CHANNEL <= adc_obj->channel && adc_obj->channel <= ADC_LAST_GPIO_CHANNEL) {
-        // Channels 0-16 correspond to real pins. Configure the GPIO pin in ADC mode.
-        const pin_obj_t *pin = pin_adc_table[adc_obj->channel];
-        mp_hal_pin_config(pin, MP_HAL_PIN_MODE_ADC, MP_HAL_PIN_PULL_NONE, 0);
-    }
-
     adc_obj->handle.Instance = ADCx;
     adcx_init_periph(&adc_obj->handle, ADC_RESOLUTION_12B);
 
@@ -431,8 +414,8 @@ STATIC mp_obj_t adc_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_
     } else {
         const pin_obj_t *pin = pin_find(pin_obj);
         if ((pin->adc_num & PIN_ADC_MASK) == 0) {
-            // No ADC1 function on that pin
-            mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("pin %q does not have ADC capabilities"), pin->name);
+            // No ADC function on the given pin.
+            mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("Pin(%q) doesn't have ADC capabilities"), pin->name);
         }
         channel = pin->adc_channel;
     }
@@ -441,11 +424,11 @@ STATIC mp_obj_t adc_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_
         mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("not a valid ADC Channel: %d"), channel);
     }
 
-
-    if (ADC_FIRST_GPIO_CHANNEL <= channel && channel <= ADC_LAST_GPIO_CHANNEL) {
-        // these channels correspond to physical GPIO ports so make sure they exist
-        if (pin_adc_table[channel] == NULL) {
-            mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("channel %d not available on this board"), channel);
+    // If this channel corresponds to a pin then configure the pin in ADC mode.
+    if (channel < MP_ARRAY_SIZE(pin_adc_table)) {
+        const pin_obj_t *pin = pin_adc_table[channel];
+        if (pin != NULL) {
+            mp_hal_pin_config(pin, MP_HAL_PIN_MODE_ADC, MP_HAL_PIN_PULL_NONE, 0);
         }
     }
 
@@ -730,11 +713,10 @@ void adc_init_all(pyb_adc_all_obj_t *adc_all, uint32_t resolution, uint32_t en_m
             mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("resolution %d not supported"), resolution);
     }
 
-    for (uint32_t channel = ADC_FIRST_GPIO_CHANNEL; channel <= ADC_LAST_GPIO_CHANNEL; ++channel) {
+    for (uint32_t channel = 0; channel < MP_ARRAY_SIZE(pin_adcall_table); ++channel) {
         // only initialise those channels that are selected with the en_mask
         if (en_mask & (1 << channel)) {
-            // Channels 0-16 correspond to real pins. Configure the GPIO pin in
-            // ADC mode.
+            // If this channel corresponds to a pin then configure the pin in ADC mode.
             const pin_obj_t *pin = pin_adcall_table[channel];
             if (pin) {
                 mp_hal_pin_config(pin, MP_HAL_PIN_MODE_ADC, MP_HAL_PIN_PULL_NONE, 0);
diff --git a/ports/stm32/boardctrl.c b/ports/stm32/boardctrl.c
index fa71d8e7f..922f218e9 100644
--- a/ports/stm32/boardctrl.c
+++ b/ports/stm32/boardctrl.c
@@ -26,7 +26,7 @@
 
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 #include "boardctrl.h"
 #include "led.h"
 #include "usrsw.h"
diff --git a/ports/stm32/boards/B_L072Z_LRWAN1/mpconfigboard.h b/ports/stm32/boards/B_L072Z_LRWAN1/mpconfigboard.h
index 0cded1bc8..dfcca72af 100644
--- a/ports/stm32/boards/B_L072Z_LRWAN1/mpconfigboard.h
+++ b/ports/stm32/boards/B_L072Z_LRWAN1/mpconfigboard.h
@@ -7,6 +7,7 @@
 
 #define MICROPY_EMIT_THUMB          (0)
 #define MICROPY_EMIT_INLINE_THUMB   (0)
+#define MICROPY_OPT_COMPUTED_GOTO   (0)
 #define MICROPY_PY_BUILTINS_COMPLEX (0)
 #define MICROPY_PY_GENERATOR_PEND_THROW (0)
 #define MICROPY_PY_MATH             (0)
@@ -67,5 +68,5 @@
 #define MICROPY_HW_USB_FS           (1)
 #define MICROPY_HW_USB_MSC          (0)
 #define MICROPY_HW_USB_HID          (0)
-#define USBD_CDC_RX_DATA_SIZE       (256)
-#define USBD_CDC_TX_DATA_SIZE       (256)
+#define MICROPY_HW_USB_CDC_RX_DATA_SIZE (256)
+#define MICROPY_HW_USB_CDC_TX_DATA_SIZE (256)
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/README.md b/ports/stm32/boards/LEGO_HUB_NO6/README.md
new file mode 100644
index 000000000..0b88cd837
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/README.md
@@ -0,0 +1,99 @@
+LEGO Hub No.6
+=============
+
+This board definition is for the LEGO Hub No. 6, a LEGO control unit with a 5x5
+LED display, 6 Powered Up ports, speaker, 6-DOF sensor, Bluetooth, external SPI
+flash storage, and a rechargeable battery.  The Hub can work without the battery if
+it is plugged in to, and powered by, its USB port.  But without the battery the LEDs
+and power on the Powered Up ports will not function.
+
+Features that are currently supported:
+- standard MicroPython
+- machine and bluetooth modules
+- filesystem
+- USB VCP, MSC and HID
+
+The Hub has a bootloader preinstalled at 0x08000000 (which is 32kiB in size) which
+cannot be erased.  This bootloader is entered by holding down the Bluetooth button,
+plugging in USB to power it up, then releasing the Bluetooth button after 5 seconds,
+at which point the USB DFU device appears.  If the battery is installed then the
+Bluetooth button's RGB LED will cycle colours.  When this bootloader is active, the
+flash from 0x08008000 and up can be erased and programmed via USB DFU.
+
+The built-in bootloader has some drawbacks: it cannot be entered programmatically,
+and it does not keep the Hub powered up when running from battery (which requires
+keeping BAT_PWR_EN high).  As such, this board is configured to work with mboot as
+a secondary bootloader: mboot is placed at 0x08008000 and the main application
+firmware at 0x08010000.  When mboot is installed it can be entered programatically
+via machine.bootloader(), or by holding down the left arrow button when powering
+on the Hub and waiting until the display says "B" before releasing the button.
+
+Backing up original Hub firmware
+--------------------------------
+
+Before install MicroPython it is advised to backup the original LEGO firmware that
+the Hub comes installed with.  To do this, enter the built-in bootloader by holding
+down the Bluetooth button for 5 seconds while powering up the Hub via USB.  Then
+run the following command from the root of this repository:
+
+    $ cd ports/stm32
+    $ make BOARD=LEGO_HUB_NO6 backup-hub-firmware
+
+This will create a file called `lego_hub_firmware.dfu`.  Put this file in a safe
+location.  To restore it, enter the built-in bootloader again and run:
+
+    $ make BOARD=LEGO_HUB_NO6 restore-hub-firmware
+
+This will restore the original firmware but not the filesystem.  To recreate the
+original filesystem the Hub must be updated using the appropriate LEGO PC
+application.
+
+Installing MicroPython
+----------------------
+
+You first need to build and install mboot, which only needs to be done once.  From
+the root of this repository run:
+
+    $ cd ports/stm32/mboot
+    $ make BOARD=LEGO_HUB_NO6
+
+Now enter the built-in bootloader by holding down the Bluetooth button for 5
+seconds while powering up the Hub via USB.  Then run:
+
+    $ make BOARD=LEGO_HUB_NO6 deploy
+
+mboot should now be installed.  Enter mboot by holding down the left arrow
+button when powering up the Hub.  The display will cycle the letters: N, S, F, B.
+When it gets to "B" release the left arrow and it will start mboot.  The Hub then
+blinks the centre button red once per second, and appears as a USB DFU device.
+
+Now build MicroPython (start at the root of this repository):
+
+    $ cd mpy-cross
+    $ make
+    $ cd ../ports/stm32
+    $ make submodules
+    $ make BOARD=LEGO_HUB_NO6
+
+And deploy to the Hub (making sure mboot is active, the centre button is blinking
+red):
+
+    $ make BOARD=LEGO_HUB_NO6 deploy
+
+If successful, the Hub should now appear as a USB serial and mass storage device.
+
+Using MicroPython on the Hub
+----------------------------
+
+Access the MicroPython REPL using mpremote (pip install mpremote), or with any
+serial terminal program.
+
+To scan for BLE devices:
+
+    >>> import bluetooth
+    >>> ble = bluetooth.BLE()
+    >>> ble.irq(lambda *x: print(*x))
+    >>> ble.active(1)
+    >>> ble.gap_scan(2000, 625, 625)
+
+Use help("modules") to see available built-in modules.
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/bdev.c b/ports/stm32/boards/LEGO_HUB_NO6/bdev.c
new file mode 100644
index 000000000..a68b812ed
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/bdev.c
@@ -0,0 +1,64 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/obj.h"
+#include "storage.h"
+#include "spi.h"
+
+#define CMD_EXIT_4_BYTE_ADDRESS_MODE (0xE9)
+
+STATIC const spi_proto_cfg_t spi_bus = {
+    .spi = &spi_obj[1], // SPI2 hardware peripheral
+    .baudrate = 25000000,
+    .polarity = 0,
+    .phase = 0,
+    .bits = 8,
+    .firstbit = SPI_FIRSTBIT_MSB,
+};
+
+STATIC mp_spiflash_cache_t spi_bdev_cache;
+
+const mp_spiflash_config_t spiflash_config = {
+    .bus_kind = MP_SPIFLASH_BUS_SPI,
+    .bus.u_spi.cs = MICROPY_HW_SPIFLASH_CS,
+    .bus.u_spi.data = (void *)&spi_bus,
+    .bus.u_spi.proto = &spi_proto,
+    .cache = &spi_bdev_cache,
+};
+
+spi_bdev_t spi_bdev;
+
+int32_t board_bdev_ioctl(void) {
+    int32_t ret = spi_bdev_ioctl(&spi_bdev, BDEV_IOCTL_INIT, (uint32_t)&spiflash_config);
+
+    // Exit 4-byte address mode
+    uint8_t cmd = CMD_EXIT_4_BYTE_ADDRESS_MODE;
+    mp_hal_pin_write(MICROPY_HW_SPIFLASH_CS, 0);
+    spi_proto.transfer(MP_OBJ_FROM_PTR(&spi_bus), 1, &cmd, NULL);
+    mp_hal_pin_write(MICROPY_HW_SPIFLASH_CS, 1);
+
+    return ret;
+}
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/bluetooth_init_cc2564C_1.5.c b/ports/stm32/boards/LEGO_HUB_NO6/bluetooth_init_cc2564C_1.5.c
new file mode 100644
index 000000000..ec41fdfee
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/bluetooth_init_cc2564C_1.5.c
@@ -0,0 +1,616 @@
+// This file contains CC256x initialisation code, and was generated by BTstack via:
+//  $ cd chipset/cc256x
+//  $ make -f Makefile.inc BTSTACK_ROOT=../.. bluetooth_init_cc2564C_1.4.c
+#if !BUILDING_MBOOT
+ 
+ // init script created from
+// - /Users/dktobthy/Downloads/cc256xc_bt_spv1.5/CC256XC_BT_SP/v1.5/initscripts-TIInit_6.12.26.bts
+// - AKA TIInit_6.12.26.bts
+// - /Users/dktobthy/Downloads/cc256xc_bt_spv1.5/CC256XC_BT_SP/v1.5/initscripts-TIInit_6.12.26_ble_add-on.bts
+#include <stdint.h>
+#include "lib/btstack/chipset/cc256x/btstack_chipset_cc256x.h"
+
+
+const uint16_t cc256x_init_script_lmp_subversion = 0x9a1a;
+
+uint16_t btstack_chipset_cc256x_lmp_subversion(void){
+    return cc256x_init_script_lmp_subversion;
+}
+
+#if defined(__GNUC__) && defined(__MSP430X__) && (__MSP430X__ > 0)
+__attribute__((section (".fartext")))
+#endif
+#ifdef __AVR__
+__attribute__((__progmem__))
+#endif
+const uint8_t cc256x_init_script[] = {
+
+    // #--------------------------------------------------------------------------------
+    // # Description : Orca C ROM Initialization Script
+    // #
+    // # Compatibility: Orca, 12.0.26 ROM
+    // #
+    // # Last Updated: 17-May-2021  10:31:30.07
+    // #
+    // # Version     : 12_26.24
+    // #
+    // #
+    // #
+    // #
+    // # Notes       : Use this script on Orca C, 12.0.26 ROM device only (FW v12.0.26)
+    // #--------------------------------------------------------------------------------
+    // #################################################################
+    // ## START of CC256x Add-On
+    // #################################################################
+    // 
+    // ## Change UART baudrate
+    // 
+    // #################################################################
+    // ## END of CC256x Add-On
+    // #################################################################
+    // 
+    0x01, 0x37, 0xfe, 0x02, 0x0c, 0x1a, 
+
+    // 
+    // 
+    0x01, 0x05, 0xff, 0xff, 0xd0, 0x65, 0x08, 0x00, 0xfa, 0x0c, 0x1a, 0x09, 0x18, 0x01, 0x6a, 
+    0xc8, 0x7b, 0x00, 0x02, 0x89, 0x7b, 0x01, 0x43, 0x09, 0x48, 0x51, 0x30, 0x02, 0x88, 0x06, 
+    0x48, 0x91, 0x42, 0x03, 0xd1, 0x04, 0x49, 0x09, 0x78, 0x01, 0x29, 0x01, 0xd0, 0x5d, 0x30, 
+    0xf7, 0x46, 0xff, 0x30, 0xd8, 0x30, 0xf7, 0x46, 0x76, 0x24, 0x08, 0x00, 0xbd, 0x28, 0x02, 
+    0x00, 0x69, 0x53, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xb5, 0x00, 
+    0x69, 0xff, 0x21, 0x02, 0x31, 0x09, 0x5c, 0x09, 0x29, 0x05, 0xd1, 0x01, 0x21, 0x00, 0x22, 
+    0x8e, 0x46, 0x6d, 0x4b, 0xfe, 0x44, 0x18, 0x47, 0x00, 0xbd, 0x6c, 0x4a, 0x11, 0x88, 0x01, 
+    0x20, 0x40, 0x03, 0x08, 0x43, 0x10, 0x80, 0xf7, 0x46, 0x30, 0xb5, 0x00, 0x69, 0xf4, 0x21, 
+    0x08, 0x5c, 0x01, 0x28, 0x16, 0xd1, 0xea, 0x48, 0x00, 0x78, 0x03, 0x28, 0x12, 0xd0, 0x00, 
+    0x25, 0x28, 0x1c, 0xe8, 0x49, 0x01, 0x24, 0xa6, 0x46, 0xe7, 0x4a, 0xfe, 0x44, 0x10, 0x47, 
+    0x00, 0x28, 0x08, 0xd0, 
+
+    0x01, 0x05, 0xff, 0xff, 0xca, 0x66, 0x08, 0x00, 0xfa, 0xe6, 0x49, 0xe6, 0x4a, 0xbb, 0x32, 
+    0x20, 0x20, 0x2b, 0x1c, 0xa6, 0x46, 0xe5, 0x4c, 0xfe, 0x44, 0x20, 0x47, 0x30, 0xbd, 0x70, 
+    0xb5, 0x85, 0x69, 0x00, 0x7d, 0x80, 0x1f, 0x11, 0xd0, 0x47, 0x38, 0x2e, 0xd1, 0xa9, 0x79, 
+    0x28, 0x20, 0x48, 0x43, 0xdf, 0x4a, 0x10, 0x18, 0x23, 0x22, 0x12, 0x5c, 0x01, 0x2a, 0x25, 
+    0xd1, 0x80, 0x7b, 0x00, 0x28, 0x22, 0xd0, 0xdb, 0x4a, 0x00, 0x20, 0x50, 0x54, 0x70, 0xbd, 
+    0x01, 0x24, 0xa6, 0x46, 0xd9, 0x48, 0xfe, 0x44, 0x00, 0x47, 0x01, 0x28, 0x05, 0xd0, 0xa6, 
+    0x46, 0xd6, 0x48, 0xfe, 0x44, 0x00, 0x47, 0x04, 0x28, 0x11, 0xd1, 0xe8, 0x78, 0x00, 0x28, 
+    0x0e, 0xd1, 0x0e, 0x26, 0x31, 0x1c, 0xd3, 0x4d, 0x28, 0x1c, 0x14, 0x38, 0xa6, 0x46, 0xd0, 
+    0x4a, 0xfe, 0x44, 0x10, 0x47, 0x28, 0x1c, 0x31, 0x1c, 0xa6, 0x46, 0xcd, 0x4a, 0xfe, 0x44, 
+    0x10, 0x47, 0x70, 0xbd, 0x70, 0xb5, 0x01, 0x1c, 0x88, 0x69, 0x89, 0x8a, 0xcb, 0x4a, 0x89, 
+    0x1a, 0x1c, 0xd0, 0x1c, 0x39, 0x20, 0xd1, 0xc5, 0x7a, 0x01, 0x21, 0x0c, 0x1c, 0x8e, 0x46, 
+    0xc8, 0x4a, 0xfe, 0x44, 0x10, 0x47, 0x06, 0x1c, 0x10, 0x20, 0xa6, 0x46, 0xc6, 0x49, 0xfe, 
+    0x44, 0x08, 0x47, 0x00, 0x2d, 0x11, 0xd0, 0x02, 0x2e, 0x0f, 0xd0, 0xc3, 0x49, 0xc4, 0x4a, 
+    0xd9, 0x32, 0x20, 0x20, 0x00, 0x23, 0xa6, 0x46, 0xb7, 0x4c, 0xfe, 0x44, 0x20, 0x47, 0x70, 
+    0xbd, 0xc0, 0x7a, 0x00, 0x28, 0x02, 0xd1, 0x00, 0x20, 0xbe, 0x49, 0x08, 0x70, 0x70, 0xbd, 
+    0x00, 0xb5, 0x00, 0x69, 0xff, 0x21, 0x04, 0x31, 0x09, 0x5c, 0x06, 0x29, 0x06, 0xd1, 0xff, 
+    0x21, 0x05, 0x31, 0x0a, 0x5c, 0x2c, 0x2a, 0x01, 0xd1, 0x2d, 0x22, 0x0a, 0x54, 0xff, 0x21, 
+    0x05, 0x31, 0x09, 0x5c, 
+
+    0x01, 0x05, 0xff, 0xff, 0xc4, 0x67, 0x08, 0x00, 0xfa, 0x34, 0x29, 0x11, 0xd1, 0xff, 0x21, 
+    0x0b, 0x31, 0x09, 0x5c, 0x91, 0x29, 0x0c, 0xd1, 0xf1, 0x21, 0x09, 0x5c, 0x60, 0x22, 0x4a, 
+    0x43, 0xeb, 0x4b, 0x00, 0x21, 0x99, 0x54, 0x06, 0x21, 0x01, 0x22, 0x96, 0x46, 0xe9, 0x4a, 
+    0xfe, 0x44, 0x10, 0x47, 0x00, 0xbd, 0xf0, 0xb5, 0x06, 0x1c, 0xf7, 0x69, 0x08, 0x20, 0xc0, 
+    0x19, 0x01, 0x24, 0xa6, 0x46, 0xe4, 0x49, 0xfe, 0x44, 0x08, 0x47, 0xc1, 0x7b, 0x09, 0x02, 
+    0x80, 0x7b, 0x08, 0x43, 0x05, 0x04, 0x2d, 0x0c, 0x02, 0x2d, 0x12, 0xd0, 0xef, 0x48, 0x00, 
+    0x88, 0xa8, 0x42, 0x0e, 0xd1, 0xee, 0x48, 0x00, 0x78, 0x01, 0x28, 0x0a, 0xd1, 0xed, 0x48, 
+    0x82, 0x8f, 0x81, 0x6b, 0x08, 0x1c, 0x10, 0x43, 0x04, 0xd0, 0x38, 0x1c, 0xa6, 0x46, 0xea, 
+    0x4b, 0xfe, 0x44, 0x18, 0x47, 0x35, 0x60, 0xe9, 0x48, 0x24, 0x30, 0x30, 0x62, 0xf0, 0xbd, 
+    0xc0, 0x46, 0xdd, 0x9d, 0x00, 0x00, 0x3e, 0xa6, 0x1b, 0x00, 0xf0, 0xb5, 0x86, 0xb0, 0x04, 
+    0x90, 0x81, 0x69, 0x05, 0x91, 0x81, 0x8a, 0xe2, 0x48, 0x09, 0x1a, 0xdc, 0x4d, 0x00, 0xd1, 
+    0xba, 0xe0, 0xe1, 0x4a, 0x89, 0x1a, 0x00, 0xd1, 0xaf, 0xe0, 0x07, 0x38, 0x09, 0x1a, 0x35, 
+    0xd0, 0xde, 0x48, 0x09, 0x1a, 0x28, 0xd0, 0x05, 0x39, 0x26, 0xd0, 0x13, 0x39, 0x33, 0xd1, 
+    0xdc, 0x48, 0x05, 0x1c, 0x84, 0x3d, 0x00, 0x78, 0x02, 0x28, 0x2d, 0xd1, 0x01, 0x24, 0xa6, 
+    0x46, 0xd9, 0x48, 0xfe, 0x44, 0x00, 0x47, 0x00, 0x28, 0x26, 0xd1, 0xa6, 0x46, 0xd7, 0x48, 
+    0xfe, 0x44, 0x00, 0x47, 0x00, 0x28, 0x20, 0xd1, 0xa6, 0x46, 0xd5, 0x48, 0xfe, 0x44, 0x00, 
+    0x47, 0x00, 0x28, 0x1a, 0xd1, 0x28, 0x78, 0x00, 0x28, 0x17, 0xd1, 0xa8, 0x78, 0x00, 0x28, 
+    0x14, 0xd1, 0xa6, 0x20, 
+
+    0x01, 0x05, 0xff, 0xff, 0xbe, 0x68, 0x08, 0x00, 0xfa, 0xa6, 0x46, 0xcf, 0x49, 0xfe, 0x44, 
+    0x08, 0x47, 0xc4, 0xe0, 0x05, 0x98, 0x81, 0x88, 0x41, 0x18, 0x08, 0x7c, 0x02, 0x28, 0x00, 
+    0xda, 0xbd, 0xe0, 0x80, 0x1e, 0x08, 0x74, 0xba, 0xe0, 0x51, 0x3d, 0x28, 0x78, 0x2a, 0x28, 
+    0x02, 0xd0, 0x33, 0x28, 0x00, 0xd0, 0xb3, 0xe0, 0x0e, 0x21, 0x05, 0x98, 0x0f, 0x18, 0x44, 
+    0x20, 0x0c, 0x21, 0x1a, 0x22, 0x01, 0x24, 0xa6, 0x46, 0xc2, 0x4b, 0xfe, 0x44, 0x18, 0x47, 
+    0xc1, 0x4e, 0xb1, 0x78, 0xf2, 0x78, 0xc1, 0x48, 0xa6, 0x46, 0xc1, 0x4b, 0xfe, 0x44, 0x18, 
+    0x47, 0x06, 0x21, 0x05, 0x98, 0x81, 0x80, 0x28, 0x78, 0xbf, 0x4d, 0x2a, 0x28, 0x26, 0xd0, 
+    0x0a, 0x26, 0x3e, 0x70, 0x01, 0x37, 0x38, 0x1c, 0x00, 0x21, 0xa6, 0x46, 0xba, 0x4a, 0xfe, 
+    0x44, 0x10, 0x47, 0x07, 0x1c, 0x3e, 0x70, 0x01, 0x37, 0x38, 0x1c, 0x0d, 0x21, 0xa6, 0x46, 
+    0xb5, 0x4a, 0xfe, 0x44, 0x10, 0x47, 0x07, 0x1c, 0xa6, 0x46, 0xb5, 0x48, 0xfe, 0x44, 0x00, 
+    0x47, 0x81, 0x02, 0xae, 0x48, 0xc0, 0x78, 0x40, 0x06, 0x40, 0x0e, 0x08, 0x43, 0x05, 0x43, 
+    0x29, 0x04, 0x09, 0x0c, 0x38, 0x1c, 0xa6, 0x46, 0xac, 0x4a, 0xfe, 0x44, 0x10, 0x47, 0x08, 
+    0x26, 0x24, 0xe0, 0x08, 0x26, 0x3e, 0x70, 0x01, 0x37, 0x38, 0x1c, 0x00, 0x21, 0xa6, 0x46, 
+    0xa6, 0x4a, 0xfe, 0x44, 0x10, 0x47, 0x07, 0x1c, 0x3e, 0x70, 0x01, 0x37, 0x38, 0x1c, 0x0d, 
+    0x21, 0xa6, 0x46, 0xa2, 0x4a, 0xfe, 0x44, 0x10, 0x47, 0x07, 0x1c, 0xa6, 0x46, 0xa1, 0x48, 
+    0xfe, 0x44, 0x00, 0x47, 0x81, 0x02, 0x9a, 0x48, 0xc0, 0x78, 0x40, 0x06, 0x40, 0x0e, 0x08, 
+    0x43, 0x05, 0x43, 0x29, 0x04, 0x09, 0x0c, 0x38, 0x1c, 0xa6, 0x46, 0x98, 0x4a, 0xfe, 0x44, 
+    0x10, 0x47, 0x05, 0x98, 
+
+    0x01, 0x05, 0xff, 0xff, 0xb8, 0x69, 0x08, 0x00, 0xfa, 0x46, 0x80, 0xff, 0x21, 0x02, 0x31, 
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+    0xb0, 0x45, 0x69, 0x86, 0x69, 0xc0, 0x69, 0x02, 0x90, 0x0f, 0x6a, 0x48, 0x6a, 0x03, 0x90, 
+    0x88, 0x6b, 0x04, 0x90, 0x28, 0x1c, 0x00, 0x95, 0x31, 0x6a, 0x89, 0x00, 0x4d, 0x19, 0x01, 
+    0x95, 0x4d, 0x19, 0x31, 0x68, 0x01, 0x29, 0x0d, 0xd1, 0x72, 0x69, 0x39, 0x1c, 0x01, 0x24, 
+    0xa6, 0x46, 0x0d, 0x4b, 0xfe, 0x44, 0x18, 0x47, 0x72, 0x69, 0x01, 0x98, 0xb9, 0x18, 0xa6, 
+    0x46, 0x09, 0x4b, 0xfe, 0x44, 0x18, 0x47, 0x68, 0x46, 0x02, 0x99, 0x2a, 0x1c, 0x01, 0x24, 
+    0xa6, 0x46, 0x71, 0x4b, 0xfe, 0x44, 0x18, 0x47, 0x73, 0x49, 0x70, 0x4d, 0x00, 0x28, 0x06, 
+    0xd0, 0x0c, 0x70, 0x28, 0x1c, 0x21, 0x30, 0x0d, 0xe0, 0xc0, 0x46, 0x5d, 0x5f, 0x05, 0x00, 
+    0x00, 0x20, 0x08, 0x70, 0xb2, 0x69, 0x03, 0x98, 0x04, 0x99, 0xa6, 0x46, 0x69, 0x4b, 0xfe, 
+    0x44, 0x18, 0x47, 0x28, 0x1c, 0xa9, 0x30, 0x05, 0xb0, 0xf0, 0xbd, 0x69, 0x48, 0x00, 0x78, 
+    0x00, 0x07, 0x40, 0x0e, 0x89, 0x6b, 0x49, 0x06, 0x89, 0x0c, 0x08, 0x18, 0x64, 0x49, 0x08, 
+    0x80, 0x65, 0x48, 0xc5, 0x30, 0xf7, 0x46, 0x01, 0x1c, 0x0a, 0x79, 0x63, 0x48, 0x06, 0x2a, 
+    0x03, 0xdb, 0x92, 0x1f, 0x4a, 0x60, 0x2f, 0x30, 0xf7, 0x46, 0x79, 0x30, 0xf7, 0x46, 0x01, 
+    0x1c, 0x88, 0x69, 0x43, 0x78, 0x3e, 0x22, 0x1a, 0x40, 0x5d, 0x48, 0x06, 0x2a, 0x05, 0xdb, 
+    0x9a, 0x06, 0x92, 0x0e, 
+
+    0x01, 0x05, 0xff, 0xff, 0x5e, 0x78, 0x08, 0x00, 0xfa, 0x06, 0x3a, 0x4a, 0x60, 0x23, 0x30, 
+    0xf7, 0x46, 0x49, 0x30, 0xf7, 0x46, 0x30, 0xb5, 0x45, 0x68, 0xff, 0x20, 0x11, 0x30, 0x40, 
+    0x5d, 0x80, 0x09, 0x0c, 0xd3, 0x11, 0x21, 0x09, 0x01, 0x4a, 0x5d, 0xdf, 0x20, 0x10, 0x40, 
+    0x48, 0x55, 0x28, 0x1c, 0x00, 0x21, 0x01, 0x22, 0x96, 0x46, 0x50, 0x4a, 0xfe, 0x44, 0x10, 
+    0x47, 0x01, 0x20, 0x04, 0x1c, 0x86, 0x46, 0x4e, 0x49, 0xfe, 0x44, 0x08, 0x47, 0xa9, 0x8b, 
+    0x28, 0x1c, 0xa6, 0x46, 0x4c, 0x4a, 0xfe, 0x44, 0x10, 0x47, 0x4c, 0x48, 0x9b, 0x30, 0x30, 
+    0xbd, 0x6d, 0x95, 0x00, 0x00, 0x4d, 0x96, 0x01, 0x00, 0x69, 0x53, 0x08, 0x00, 0x10, 0xb5, 
+    0x02, 0x1c, 0x4c, 0x20, 0x43, 0x5a, 0x46, 0x48, 0x06, 0x2b, 0x0d, 0xdb, 0x19, 0x24, 0xe4, 
+    0x01, 0xa3, 0x42, 0x09, 0xdc, 0x54, 0x23, 0x59, 0x5a, 0x0a, 0x29, 0x05, 0xdb, 0xa1, 0x42, 
+    0x03, 0xdc, 0x00, 0x21, 0x51, 0x60, 0x99, 0x30, 0x10, 0xbd, 0x3f, 0x4a, 0x00, 0x21, 0xff, 
+    0x23, 0x21, 0x33, 0x4b, 0x43, 0xd3, 0x5c, 0xff, 0x2b, 0x04, 0xd0, 0x49, 0x1c, 0x09, 0x06, 
+    0x09, 0x0e, 0x0a, 0x29, 0xf4, 0xdb, 0x49, 0x1e, 0x39, 0x4a, 0x11, 0x70, 0x01, 0x21, 0x38, 
+    0x4a, 0x11, 0x70, 0xff, 0x30, 0x26, 0x30, 0x10, 0xbd, 0xc0, 0x46, 0x7b, 0x5e, 0x02, 0x00, 
+    0x45, 0x10, 0x08, 0x00, 0x54, 0x24, 0x08, 0x00, 0x07, 0x0e, 0x00, 0x00, 0x7f, 0xb5, 0x45, 
+    0x69, 0x10, 0x26, 0x32, 0x1c, 0x68, 0x46, 0x00, 0x21, 0x01, 0x24, 0xa6, 0x46, 0x2e, 0x4b, 
+    0xfe, 0x44, 0x18, 0x47, 0xff, 0x20, 0x31, 0x30, 0x40, 0x19, 0x69, 0x46, 0x32, 0x1c, 0xa6, 
+    0x46, 0x2b, 0x4b, 0xfe, 0x44, 0x18, 0x47, 0x00, 0x28, 0x08, 0xd1, 0xff, 0x20, 0x25, 0x30, 
+    0x05, 0x21, 0x41, 0x55, 
+
+    0x01, 0x05, 0xff, 0xff, 0x58, 0x79, 0x08, 0x00, 0xfa, 0x28, 0x1c, 0xa6, 0x46, 0x26, 0x49, 
+    0xfe, 0x44, 0x08, 0x47, 0x26, 0x48, 0x6f, 0x30, 0x00, 0x90, 0x7f, 0xbd, 0x25, 0x48, 0xa5, 
+    0x30, 0xf7, 0x46, 0x2b, 0xf0, 0x04, 0x00, 0xff, 0xff, 0xff, 0x01, 0x5b, 0x32, 0x08, 0x00, 
+    0x8f, 0x02, 0x00, 0x00, 0xcd, 0x92, 0x01, 0x00, 0x6f, 0x4b, 0x02, 0x00, 0x58, 0x66, 0x08, 
+    0x00, 0x43, 0x1c, 0x03, 0x00, 0xf5, 0x70, 0x00, 0x00, 0x21, 0x37, 0x05, 0x00, 0xe9, 0x36, 
+    0x05, 0x00, 0xa9, 0x36, 0x05, 0x00, 0xc3, 0x6c, 0x05, 0x00, 0xa5, 0x6c, 0x05, 0x00, 0xd1, 
+    0x1c, 0x05, 0x00, 0x8d, 0x76, 0x08, 0x00, 0x91, 0x48, 0x05, 0x00, 0x47, 0x37, 0x05, 0x00, 
+    0x63, 0x66, 0x08, 0x00, 0x1c, 0x30, 0x19, 0x00, 0x96, 0xa5, 0x1b, 0x00, 0x61, 0x61, 0x03, 
+    0x00, 0xe1, 0x72, 0x03, 0x00, 0x5f, 0x73, 0x03, 0x00, 0xf5, 0x56, 0x02, 0x00, 0xbb, 0x88, 
+    0x03, 0x00, 0x3b, 0x3b, 0x02, 0x00, 0x9d, 0xcf, 0x02, 0x00, 0x6d, 0x23, 0x03, 0x00, 0xb9, 
+    0x26, 0x08, 0x00, 0x61, 0x66, 0x08, 0x00, 0x60, 0x66, 0x08, 0x00, 0xe9, 0x63, 0x05, 0x00, 
+    0x5f, 0x6a, 0x05, 0x00, 0xd5, 0x12, 0x04, 0x00, 0x5f, 0xde, 0x04, 0x00, 0xbd, 0x65, 0x01, 
+    0x00, 0xff, 0xb5, 0x68, 0x46, 0xff, 0xf7, 0xc0, 0xf9, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 
+    0xff, 0xf7, 0xd9, 0xf9, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 0xff, 0xf7, 0x00, 0xf9, 0xff, 
+    0xbd, 0xff, 0xb5, 0x68, 0x46, 0xff, 0xf7, 0xb5, 0xf8, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 
+    0xff, 0xf7, 0x3a, 0xfa, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 0xff, 0xf7, 0x81, 0xfa, 0xff, 
+    0xbd, 0xff, 0xb5, 0x68, 0x46, 0xff, 0xf7, 0xdc, 0xf9, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 
+    0xff, 0xf7, 0xf9, 0xf9, 
+
+    0x01, 0x05, 0xff, 0x6b, 0x52, 0x7a, 0x08, 0x00, 0x66, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 
+    0xfe, 0xf7, 0x41, 0xfe, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 0xfe, 0xf7, 0x73, 0xfe, 0xff, 
+    0xbd, 0xff, 0xb5, 0x68, 0x46, 0xfe, 0xf7, 0x19, 0xfe, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 
+    0xfe, 0xf7, 0xff, 0xfd, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 0xfe, 0xf7, 0x08, 0xfe, 0xff, 
+    0xbd, 0xff, 0xb5, 0x68, 0x46, 0xff, 0xf7, 0x07, 0xf8, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 
+    0xff, 0xf7, 0x55, 0xf9, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 0xfe, 0xf7, 0xd5, 0xfe, 0xff, 
+    0xbd, 0xff, 0xb5, 0x68, 0x46, 0xfe, 0xf7, 0x7b, 0xfe, 0xff, 0xbd, 0xff, 0xb5, 0x68, 0x46, 
+    0xfe, 0xf7, 0x9c, 0xfe, 0xff, 0xbd, 
+
+    0x01, 0x05, 0xff, 0x8d, 0x78, 0x7b, 0x08, 0x00, 0x88, 0x00, 0xb5, 0xf8, 0xf0, 0xe3, 0xfa, 
+    0x00, 0xbd, 0xd7, 0x70, 0x08, 0x00, 0x79, 0x71, 0x08, 0x00, 0x3d, 0x72, 0x08, 0x00, 0x6d, 
+    0x72, 0x08, 0x00, 0x81, 0x72, 0x08, 0x00, 0x99, 0x72, 0x08, 0x00, 0x35, 0x75, 0x08, 0x00, 
+    0x89, 0x75, 0x08, 0x00, 0x95, 0x77, 0x08, 0x00, 0x61, 0x71, 0x08, 0x00, 0xd5, 0x65, 0x08, 
+    0x00, 0xe5, 0x71, 0x08, 0x00, 0x01, 0x72, 0x08, 0x00, 0x19, 0x72, 0x08, 0x00, 0x2f, 0x72, 
+    0x08, 0x00, 0x29, 0x73, 0x08, 0x00, 0x39, 0x76, 0x08, 0x00, 0x1b, 0x78, 0x08, 0x00, 0x35, 
+    0x78, 0x08, 0x00, 0x4b, 0x78, 0x08, 0x00, 0x6b, 0x78, 0x08, 0x00, 0xc5, 0x71, 0x08, 0x00, 
+    0xbd, 0x78, 0x08, 0x00, 0x25, 0x79, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x6b, 0x79, 0x08, 0x00, 
+
+    0x01, 0x05, 0xff, 0x85, 0x04, 0xf3, 0x1a, 0x00, 0x80, 0xce, 0xfb, 0x04, 0x00, 0xf4, 0x4b, 
+    0x04, 0x00, 0x0c, 0x76, 0x00, 0x00, 0x06, 0x0a, 0x02, 0x00, 0x50, 0x98, 0x00, 0x00, 0xb4, 
+    0xc6, 0x01, 0x00, 0xb8, 0x5e, 0x02, 0x00, 0x58, 0x95, 0x01, 0x00, 0x2e, 0x49, 0x05, 0x00, 
+    0xde, 0x33, 0x02, 0x00, 0x14, 0x29, 0x02, 0x00, 0x60, 0x13, 0x02, 0x00, 0xd6, 0x28, 0x05, 
+    0x00, 0x74, 0x39, 0x02, 0x00, 0x88, 0xac, 0x00, 0x00, 0x7a, 0x95, 0x00, 0x00, 0xe8, 0x72, 
+    0x00, 0x00, 0x1c, 0x62, 0x03, 0x00, 0x0e, 0x73, 0x03, 0x00, 0x7e, 0x73, 0x03, 0x00, 0x34, 
+    0xd0, 0x02, 0x00, 0x52, 0x48, 0x00, 0x00, 0x04, 0x24, 0x03, 0x00, 0xa0, 0xde, 0x04, 0x00, 
+    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 
+    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5a, 0x66, 
+    0x01, 0x00, 
+
+    0x01, 0x05, 0xff, 0xff, 0x00, 0x00, 0x18, 0x00, 0xfa, 0x70, 0xb5, 0x3a, 0x4d, 0xae, 0x7f, 
+    0x01, 0x24, 0xa6, 0x46, 0x36, 0x48, 0xfe, 0x44, 0x00, 0x47, 0xb0, 0x42, 0xf8, 0xd1, 0x03, 
+    0x20, 0x17, 0x21, 0x89, 0x01, 0xa6, 0x46, 0x32, 0x4a, 0xfe, 0x44, 0x10, 0x47, 0xad, 0x7f, 
+    0xa6, 0x46, 0x2f, 0x48, 0xfe, 0x44, 0x00, 0x47, 0xa8, 0x42, 0xf9, 0xd1, 0xfe, 0xe7, 0x30, 
+    0xb5, 0x2e, 0x49, 0x08, 0x1f, 0x2e, 0x4a, 0x10, 0x60, 0x31, 0x48, 0x02, 0x1c, 0x71, 0x3a, 
+    0x93, 0x24, 0x01, 0x23, 0xa3, 0x54, 0x2b, 0x4b, 0x0b, 0x60, 0x02, 0x23, 0x13, 0x71, 0x2a, 
+    0x4b, 0x4b, 0x60, 0x03, 0x23, 0x53, 0x71, 0x29, 0x4b, 0x8b, 0x60, 0x04, 0x23, 0x03, 0x70, 
+    0x29, 0x4b, 0xcb, 0x60, 0x05, 0x23, 0x83, 0x73, 0x28, 0x4b, 0x0b, 0x61, 0x06, 0x23, 0x03, 
+    0x73, 0x27, 0x4b, 0x4b, 0x61, 0x07, 0x23, 0x43, 0x71, 0x26, 0x4b, 0x8b, 0x61, 0x08, 0x24, 
+    0x03, 0x1c, 0x33, 0x3b, 0x1c, 0x70, 0x24, 0x4b, 0xcb, 0x61, 0x09, 0x23, 0xd3, 0x74, 0x23, 
+    0x4b, 0x0b, 0x62, 0x0a, 0x23, 0xd3, 0x71, 0xd3, 0x1d, 0x22, 0x4c, 0x4c, 0x62, 0x0b, 0x24, 
+    0x44, 0x77, 0x21, 0x4c, 0x8c, 0x62, 0x0c, 0x25, 0x04, 0x1c, 0x3d, 0x3c, 0x25, 0x70, 0x1f, 
+    0x4c, 0xcc, 0x62, 0x0f, 0x38, 0x0d, 0x24, 0x04, 0x70, 0x1d, 0x4c, 0x0c, 0x63, 0x0e, 0x24, 
+    0x04, 0x73, 0x1c, 0x4c, 0x4c, 0x63, 0x0f, 0x24, 0x44, 0x73, 0x1b, 0x4c, 0x8c, 0x63, 0x10, 
+    0x24, 0x04, 0x77, 0x1a, 0x48, 0xc8, 0x63, 0x11, 0x20, 0x10, 0x70, 0x19, 0x48, 0x08, 0x64, 
+    0x12, 0x20, 0x98, 0x76, 0x18, 0x48, 0x48, 0x64, 0x30, 0xbd, 0xc0, 0x46, 0x25, 0x86, 0x04, 
+    0x00, 0x1b, 0x90, 0x04, 0x00, 0x6c, 0x52, 0x08, 0x00, 0x08, 0x66, 0x08, 0x00, 0x20, 0x55, 
+    0x08, 0x00, 0x73, 0x7a, 
+
+    0x01, 0x05, 0xff, 0xff, 0xfa, 0x00, 0x18, 0x00, 0xfa, 0x08, 0x00, 0x5f, 0x7a, 0x08, 0x00, 
+    0x55, 0x7a, 0x08, 0x00, 0x95, 0x55, 0x08, 0x00, 0xa5, 0x7a, 0x08, 0x00, 0x7d, 0x7a, 0x08, 
+    0x00, 0x69, 0x7a, 0x08, 0x00, 0xaf, 0x7a, 0x08, 0x00, 0x9b, 0x7a, 0x08, 0x00, 0x87, 0x7a, 
+    0x08, 0x00, 0x19, 0x7a, 0x08, 0x00, 0x91, 0x7a, 0x08, 0x00, 0x23, 0x7a, 0x08, 0x00, 0x05, 
+    0x7a, 0x08, 0x00, 0x0f, 0x7a, 0x08, 0x00, 0x41, 0x7a, 0x08, 0x00, 0x4b, 0x7a, 0x08, 0x00, 
+    0x2d, 0x7a, 0x08, 0x00, 0x37, 0x7a, 0x08, 0x00, 0xf0, 0xb5, 0x31, 0x4e, 0x0c, 0x22, 0x32, 
+    0x70, 0x1a, 0x23, 0x73, 0x70, 0x09, 0x20, 0xb0, 0x70, 0x18, 0x20, 0xf0, 0x70, 0x03, 0x20, 
+    0x2e, 0x4d, 0x29, 0x1c, 0x01, 0x39, 0x01, 0x24, 0xa6, 0x46, 0x2a, 0x4f, 0xfe, 0x44, 0x38, 
+    0x47, 0xb2, 0x78, 0xf3, 0x78, 0x03, 0x20, 0x29, 0x1c, 0xa6, 0x46, 0x26, 0x4e, 0xfe, 0x44, 
+    0x30, 0x47, 0x03, 0x20, 0x29, 0x1c, 0x01, 0x31, 0xa6, 0x46, 0x25, 0x4a, 0xfe, 0x44, 0x10, 
+    0x47, 0xa6, 0x46, 0x24, 0x48, 0xfe, 0x44, 0x00, 0x47, 0x23, 0x4b, 0x00, 0x21, 0x08, 0x1c, 
+    0x1a, 0x68, 0x00, 0x2a, 0x04, 0xd0, 0x02, 0x07, 0x15, 0x0f, 0x22, 0x1c, 0xaa, 0x40, 0x11, 
+    0x43, 0x02, 0x07, 0x12, 0x0f, 0x0f, 0x2a, 0x05, 0xd1, 0xc5, 0x08, 0x06, 0x22, 0x2a, 0x40, 
+    0x1b, 0x4d, 0xa9, 0x52, 0x00, 0x21, 0x04, 0x33, 0x01, 0x30, 0x20, 0x28, 0xe9, 0xd3, 0x1a, 
+    0x48, 0x01, 0x1c, 0x50, 0x31, 0x0c, 0x70, 0x0a, 0x21, 0x16, 0x4a, 0x11, 0x70, 0x33, 0x21, 
+    0x01, 0x70, 0x00, 0x25, 0x16, 0x48, 0x05, 0x60, 0x28, 0x1c, 0xa6, 0x46, 0x16, 0x49, 0xfe, 
+    0x44, 0x08, 0x47, 0x13, 0x49, 0x08, 0x60, 0x14, 0x48, 0x05, 0x60, 0x07, 0x20, 0x14, 0x49, 
+    0x08, 0x70, 0x14, 0x4a, 
+
+    0x01, 0x05, 0xff, 0x65, 0xf4, 0x01, 0x18, 0x00, 0x60, 0x91, 0x78, 0x02, 0x20, 0x08, 0x43, 
+    0x90, 0x70, 0x12, 0x48, 0x05, 0x70, 0x12, 0x48, 0x05, 0x70, 0x12, 0x48, 0x05, 0x70, 0xf0, 
+    0xbd, 0xc0, 0x46, 0xfc, 0x53, 0x08, 0x00, 0x31, 0x90, 0x04, 0x00, 0xc6, 0x05, 0x00, 0x00, 
+    0x1b, 0x90, 0x04, 0x00, 0x33, 0x00, 0x18, 0x00, 0x80, 0x7b, 0x08, 0x00, 0x84, 0xf3, 0x1a, 
+    0x00, 0x6d, 0x22, 0x08, 0x00, 0x69, 0x53, 0x08, 0x00, 0x50, 0x66, 0x08, 0x00, 0x54, 0x66, 
+    0x08, 0x00, 0xd1, 0xa1, 0x04, 0x00, 0x5c, 0x66, 0x08, 0x00, 0xb3, 0x11, 0x08, 0x00, 0xe4, 
+    0x15, 0x08, 0x00, 0x63, 0x66, 0x08, 0x00, 0x60, 0x66, 0x08, 0x00, 0x61, 0x66, 0x08, 0x00, 
+    
+
+    0x01, 0x83, 0xff, 0x14, 0x79, 0x7b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+
+    // 
+    // ######
+    // ### Set the BT Core spec to 4.2 for Bluetopia stack compatibility
+    // ### Remove below VS command for default BT core spec 5.1
+    0x01, 0x09, 0xfd, 0x08, 0x68, 0x53, 0x08, 0x00, 0x00, 0x2a, 0x00, 0xff, 
+
+    // ######
+    // 
+    0x01, 0x0c, 0xfd, 0x09, 0x01, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0x64, 0x00, 
+
+    0x01, 0x09, 0xfd, 0x08, 0x58, 0x60, 0x1a, 0x00, 0x00, 0x10, 0x00, 0x10, 
+
+    0x01, 0x09, 0xfd, 0x08, 0x10, 0x60, 0x1a, 0x00, 0x10, 0x00, 0x10, 0x00, 
+
+    0x01, 0x1c, 0xfd, 0x14, 0xff, 0x88, 0x13, 0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0xff, 0xff, 
+    0xff, 0xff, 0xff, 0x00, 0xfa, 0x00, 0xff, 0xff, 0x00, 
+
+    // 
+    // 
+    // ##--------------------------------------------------------------------------------
+    // ## Description:   ORCA_C Commercial PHY FW Initialization Script
+    // ##--------------------------------------------------------------------------------
+    0x01, 0x76, 0xfd, 0x31, 0x01, 0x21, 0x54, 0x00, 0x00, 0x61, 0x57, 0x00, 0x00, 0x14, 0x05, 
+    0x0a, 0x05, 0x00, 0x07, 0x06, 0x0a, 0x04, 0x05, 0x08, 0x09, 0x0b, 0x0c, 0x0d, 0x0e, 0x10, 
+    0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 
+    0x10, 0x10, 0x10, 0x10, 0x00, 0x00, 0x00, 0x00, 
+
+    // BTstack: added HCI_VS_SET_POWER_VECTOR(GFSK) 0xFD82 template
+    0x01, 0x82, 0xfd, 0x14, 0x00, 0x9c, 0x18, 0xd2, 0xd2, 0xd2, 0xd2, 0xd2, 0xd2, 0xd2, 0xdc,
+    0xe6, 0xf0, 0xfa, 0x04, 0x0e, 0x18, 0xff, 0x00, 0x00,
+
+    // BTstack: added HCI_VS_SET_POWER_VECTOR(EDR2) 0xFD82 template
+    0x01, 0x82, 0xfd, 0x14, 0x01, 0x9c, 0xce, 0xce, 0xce, 0xce, 0xce, 0xce, 0xce, 0xce, 0xd8, 
+    0xe2, 0xec, 0xf6, 0x00, 0x0a, 0x14, 0xff, 0x00, 0x00,
+
+    // BTstack: added HCI_VS_SET_POWER_VECTOR(EDR3) 0xFD82 for EDR3 template
+    0x01, 0x82, 0xfd, 0x14, 0x02, 0x9c, 0xce, 0xce, 0xce, 0xce, 0xce, 0xce, 0xce, 0xce, 0xd8,
+    0xe2, 0xec, 0xf6, 0x00, 0x0a, 0x14, 0xff, 0x00, 0x00,
+
+    // BTstack: added HCI_VS_SET_CLASS2_SINGLE_POWER 0xFD87 template
+    0x01, 0x87, 0xfd, 0x03, 0x0d, 0x0d, 0x0d,
+
+    0x01, 0x80, 0xfd, 0x06, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 
+
+    0x01, 0x80, 0xfd, 0x06, 0x3c, 0xf0, 0x5f, 0x00, 0x00, 0x00, 
+
+    // 
+    // 
+    // 
+    0x01, 0x38, 0xfe, 0x00, 
+
+    // 
+    // #################################################################
+    // ## START of CC2564 Adds-On
+    // #################################################################
+    // 
+    // ## Enable fast clock XTAL support
+    0x01, 0x1c, 0xfd, 0x14, 0x01, 0x88, 0x13, 0x00, 0x00, 0xd0, 0x07, 0x00, 0x00, 0xff, 0xff, 
+    0x04, 0xff, 0xff, 0xff, 0xfa, 0x00, 0x00, 0x00, 0x00, 
+
+    // 
+    // ## Enable eHCILL
+    0x01, 0x2b, 0xfd, 0x05, 0x10, 0x00, 0x50, 0x00, 0x96, 
+
+    // 
+    0x01, 0x0c, 0xfd, 0x09, 0x01, 0x01, 0x00, 0xff, 0xff, 0xff, 0xff, 0x64, 0x00, 
+
+    // 
+    // #################################################################
+    // ## END of CC2564 Adds-On
+    // #################################################################
+    0x01, 0x5b, 0xfd, 0x02, 0x01, 0x01, 
+
+    // 
+    0x01, 0xdd, 0xfd, 0x01, 0x01, 
+
+};
+
+const uint32_t cc256x_init_script_size = 6771;
+
+#endif
\ No newline at end of file
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/board_init.c b/ports/stm32/boards/LEGO_HUB_NO6/board_init.c
new file mode 100644
index 000000000..3f22bfc8f
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/board_init.c
@@ -0,0 +1,170 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/mphal.h"
+#include "irq.h"
+
+void board_init(void) {
+    if (query_irq() == IRQ_STATE_DISABLED) {
+        enable_irq(IRQ_STATE_ENABLED);
+    }
+
+    // Enable 3V3 for all ports
+    mp_hal_pin_output(pyb_pin_PORT_3V3_EN);
+    mp_hal_pin_high(pyb_pin_PORT_3V3_EN);
+
+    // Port A
+    // Enable RX/TX buffer
+    mp_hal_pin_output(pyb_pin_PORTA_EN);
+    mp_hal_pin_low(pyb_pin_PORTA_EN);
+
+    // Port B
+    // Enable RX/TX buffer
+    mp_hal_pin_output(pyb_pin_PORTB_EN);
+    mp_hal_pin_low(pyb_pin_PORTB_EN);
+
+    // Port C
+    // Enable RX/TX buffer
+    mp_hal_pin_output(pyb_pin_PORTC_EN);
+    mp_hal_pin_low(pyb_pin_PORTC_EN);
+
+    // Port D
+    // Enable RX/TX buffer
+    mp_hal_pin_output(pyb_pin_PORTD_EN);
+    mp_hal_pin_low(pyb_pin_PORTD_EN);
+
+    // Port E
+    // Enable RX/TX buffer
+    mp_hal_pin_output(pyb_pin_PORTE_EN);
+    mp_hal_pin_low(pyb_pin_PORTE_EN);
+    // Disable RS485 driver
+    mp_hal_pin_output(pyb_pin_PORTE_RTS);
+    mp_hal_pin_low(pyb_pin_PORTE_RTS);
+
+    // Port F
+    // Enable RX/TX buffer
+    mp_hal_pin_output(pyb_pin_PORTF_EN);
+    mp_hal_pin_low(pyb_pin_PORTF_EN);
+    // Disable RS485 driver
+    mp_hal_pin_output(pyb_pin_PORTF_RTS);
+    mp_hal_pin_low(pyb_pin_PORTF_RTS);
+}
+
+#if BUILDING_MBOOT
+
+#include "mboot/mboot.h"
+#include "boardctrl.h"
+#include "adc.h"
+#include "hub_display.h"
+
+#define RESET_MODE_NUM_STATES (4)
+#define RESET_MODE_TIMEOUT_CYCLES (8)
+
+#define PATTERN_B (0x00651946)
+#define PATTERN_F (0x0021184e)
+#define PATTERN_N (0x01296ad2)
+#define PATTERN_S (0x0064104c)
+
+static void board_led_pattern(int reset_mode, uint16_t brightness) {
+    static const uint32_t pixels[] = {
+        0,
+        PATTERN_N,
+        PATTERN_S,
+        PATTERN_F,
+        PATTERN_B,
+    };
+    uint32_t pixel = pixels[reset_mode];
+    for (int i = 0; i < 25; ++i) {
+        hub_display_set(i, brightness * ((pixel >> i) & 1));
+    }
+    hub_display_update();
+}
+
+static void board_button_init(void) {
+    mp_hal_pin_config(pin_A1, MP_HAL_PIN_MODE_ADC, MP_HAL_PIN_PULL_NONE, 0);
+    adc_config(ADC1, 12);
+}
+
+static int board_button_state(void) {
+    uint16_t value = adc_config_and_read_u16(ADC1, 1, ADC_SAMPLETIME_15CYCLES);
+    return value < 44000;
+}
+
+void board_mboot_cleanup(int reset_mode) {
+    board_led_pattern(0, 0);
+    hub_display_off();
+}
+
+void board_mboot_led_init(void) {
+    hub_display_on();
+}
+
+void board_mboot_led_state(int led, int state) {
+    if (state) {
+        hub_display_set(28, 0x7fff);
+        hub_display_set(31, 0x7fff);
+    } else {
+        hub_display_set(28, 0);
+        hub_display_set(31, 0);
+    }
+    hub_display_update();
+}
+
+int board_mboot_get_reset_mode(void) {
+    board_button_init();
+    int reset_mode = BOARDCTRL_RESET_MODE_NORMAL;
+    if (board_button_state()) {
+        // Cycle through reset modes while USR is held.
+        // Timeout is roughly 20s, where reset_mode=1.
+        systick_init();
+        hub_display_on();
+        reset_mode = 0;
+        for (int i = 0; i < (RESET_MODE_NUM_STATES * RESET_MODE_TIMEOUT_CYCLES + 1) * 32; i++) {
+            if (i % 32 == 0) {
+                if (++reset_mode > RESET_MODE_NUM_STATES) {
+                    reset_mode = BOARDCTRL_RESET_MODE_NORMAL;
+                }
+                board_led_pattern(reset_mode, 0x7fff);
+            }
+            if (!board_button_state()) {
+                break;
+            }
+            mp_hal_delay_ms(19);
+        }
+        // Flash the selected reset mode.
+        for (int i = 0; i < 6; i++) {
+            board_led_pattern(reset_mode, 0x0fff);
+            mp_hal_delay_ms(50);
+            board_led_pattern(reset_mode, 0x7fff);
+            mp_hal_delay_ms(50);
+        }
+        mp_hal_delay_ms(300);
+    }
+    board_led_pattern(0, 0);
+    return reset_mode;
+}
+
+#endif
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/cc2564.c b/ports/stm32/boards/LEGO_HUB_NO6/cc2564.c
new file mode 100644
index 000000000..c54daf300
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/cc2564.c
@@ -0,0 +1,85 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "timer.h"
+#include "extmod/mpbthci.h"
+
+#if !BUILDING_MBOOT
+
+#define CC2564_PIN_CTS (pyb_pin_BT_CTS)
+#define CC2564_PIN_RTS (pyb_pin_BT_RTS)
+#define CC2564_PIN_BT_SLOWCLK (pyb_pin_BT_SLOWCLK)
+#define CC2564_PIN_BT_ENABLE (pyb_pin_BT_ENABLE)
+
+STATIC void cc2564_wait_cts_low(mp_hal_pin_obj_t cts, uint32_t timeout_ms) {
+    for (int i = 0; i < timeout_ms; ++i) {
+        if (mp_hal_pin_read(cts) == 0) {
+            break;
+        }
+        mp_hal_delay_ms(1);
+    }
+}
+
+int mp_bluetooth_hci_controller_init(void) {
+    // Pull BTNSHUTD low to disable chip.
+    mp_hal_pin_output(CC2564_PIN_BT_ENABLE);
+    mp_hal_pin_low(CC2564_PIN_BT_ENABLE);
+
+    // Output a 32768Hz signal on BTSLOWCLK.
+    //  tim8 = pyb.Timer(8, freq=32768)
+    //  tim8_ch4 = tim8.channel(4, pyb.Timer.PWM, pin=btclk)
+    //  tim8_ch4.pulse_width_percent(50)
+    mp_obj_t args[6] = { MP_OBJ_NEW_SMALL_INT(8), MP_OBJ_NEW_QSTR(MP_QSTR_freq), MP_OBJ_NEW_SMALL_INT(32768), MP_OBJ_NULL };
+    mp_obj_t tim8 = pyb_timer_type.make_new(&pyb_timer_type, 1, 1, args);
+    mp_load_method(tim8, MP_QSTR_channel, args);
+    args[2] = MP_OBJ_NEW_SMALL_INT(4);
+    args[3] = MP_OBJ_NEW_SMALL_INT(0); // CHANNEL_MODE_PWM_NORMAL
+    args[4] = MP_OBJ_NEW_QSTR(MP_QSTR_pin);
+    args[5] = (mp_obj_t)CC2564_PIN_BT_SLOWCLK;
+    mp_obj_t tim8_ch4 = mp_call_method_n_kw(2, 1, args);
+    mp_load_method(tim8_ch4, MP_QSTR_pulse_width_percent, args);
+    args[2] = MP_OBJ_NEW_SMALL_INT(50);
+    mp_call_method_n_kw(1, 0, args);
+
+    // Pull BTNSHUTD high to enable chip and wait for CTS to go low to indicate ready.
+    mp_hal_pin_high(CC2564_PIN_BT_ENABLE);
+    cc2564_wait_cts_low(CC2564_PIN_CTS, 500);
+
+    return 0;
+}
+
+int mp_bluetooth_hci_controller_deinit(void) {
+    // Pull BTNSHUTD low to disable chip.
+    mp_hal_pin_low(CC2564_PIN_BT_ENABLE);
+
+    return 0;
+}
+
+#endif
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/hub_display.c b/ports/stm32/boards/LEGO_HUB_NO6/hub_display.c
new file mode 100644
index 000000000..1efc388c7
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/hub_display.c
@@ -0,0 +1,180 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/mphal.h"
+#include "hub_display.h"
+
+// Map pixel number 0-24, and 25-36 to TLC bit number.
+static const uint8_t hub_display_pixel_map[] = {
+    // 5x5 display
+     9,  11,   6,   1,  14,
+    10,  19,   8,   0,  26,
+    23,  18,   3,   2,  24,
+    21,  20,  15,  13,  25,
+    22,   7,  17,  12,  38,
+    // RGB Bluetooth button
+    27, 28, 29,
+    // RGB middle button (left and right)
+    39, 40, 41, 42, 43, 44,
+    // RGB battery indicator
+    45, 46, 47,
+};
+
+static bool hub_display_init;
+static uint8_t hub_display_gs_state[96];
+
+static void hub_display_tim_init(void) {
+    // TLC maximum GSCLK freq: 33MHz
+
+    // tim12, ch2, pwm
+
+    TIM_TypeDef *tim = TIM12;
+
+    __HAL_RCC_TIM12_CLK_ENABLE();
+    tim->CR1 = TIM_CR1_ARPE;
+
+    // Configure PWM mode.
+    uint32_t ch = 1; // ch2
+    uint32_t reg = 6 << TIM_CCMR1_OC1M_Pos // PWM1 mode
+        | 1 << TIM_CCMR1_OC1PE_Pos // preload enabled
+        | 0 << TIM_CCMR1_CC1S_Pos // output mode
+        ;
+    uint32_t shift = 8 * (ch & 1);
+    tim->CCMR1 = (tim->CCMR1 & ~(0xff << shift)) | reg << shift;
+
+    // Enable output on pin, active high for normal channel.
+    reg = TIM_CCER_CC1E;
+    shift = 4 * ch;
+    tim->CCER = (tim->CCER & ~(0xf << shift)) | reg << shift;
+
+    // Enable the timer if it's not already running.
+    tim->CR1 |= TIM_CR1_CEN;
+
+    // fast
+    tim->PSC = 0;
+    tim->ARR = 2;
+
+    // 50% duty
+    tim->CCR2 = 2;
+    tim->EGR = 1; // UG
+
+    mp_hal_pin_config(pin_B15, MP_HAL_PIN_MODE_ALT, MP_HAL_PIN_PULL_NONE, 9);
+}
+
+static void hub_display_spi_init(void) {
+    // TLC maximum SPI freq: 25MHz
+
+    SPI_TypeDef *spi = SPI1;
+
+    __HAL_RCC_SPI1_CLK_ENABLE();
+    spi->CR1 = SPI_CR1_SSM | SPI_CR1_SSI | 0 << SPI_CR1_BR_Pos | SPI_CR1_MSTR;
+    spi->CR1 |= SPI_CR1_SPE;
+
+    mp_hal_pin_config(pin_A5, MP_HAL_PIN_MODE_ALT, MP_HAL_PIN_PULL_NONE, 5);
+    mp_hal_pin_config(pin_A6, MP_HAL_PIN_MODE_ALT, MP_HAL_PIN_PULL_NONE, 5);
+    mp_hal_pin_config(pin_A7, MP_HAL_PIN_MODE_ALT, MP_HAL_PIN_PULL_NONE, 5);
+}
+
+static void hub_display_spi_write(uint8_t value) {
+    SPI_TypeDef *spi = SPI1;
+    spi->DR = value;
+    while (!(spi->SR & SPI_SR_TXE)) {
+    }
+}
+
+// dc: dot control
+// mc: maximum current
+// bc: global brightness control
+// fc: function control
+static void hub_display_latch_ctrl(uint8_t dc, uint32_t mc, uint32_t bc, uint8_t fc) {
+    hub_display_spi_write(1);                   // bit 768
+    hub_display_spi_write(0x96);                // bits 760-767
+    for (int i = 0; i < 48; ++i) {
+        hub_display_spi_write(0);
+    }
+    hub_display_spi_write(fc >> 2);             // bits 368-375
+    hub_display_spi_write(fc << 6 | bc >> 15);  // bits 360-367
+    hub_display_spi_write(bc >> 7);             // bits 352-359
+    hub_display_spi_write(bc << 1 | mc >> 8);   // bits 344-351
+    hub_display_spi_write(mc);                  // bits 336-343
+    for (int i = 0; i < 42; ++i) {
+        hub_display_spi_write(dc);
+    }
+    mp_hal_pin_high(pin_A15);
+    mp_hal_delay_us(1);
+    mp_hal_pin_low(pin_A15);
+}
+
+void hub_display_set(uint8_t led, uint16_t value) {
+    led = hub_display_pixel_map[led];
+    hub_display_gs_state[led * 2] = value;
+    hub_display_gs_state[led * 2 + 1] = value >> 8;
+}
+
+void hub_display_update(void) {
+    if (!hub_display_init) {
+        return;
+    }
+    hub_display_spi_write(0);
+    for (int i = 0; i < 96; ++i) {
+        hub_display_spi_write(hub_display_gs_state[95 - i]);
+    }
+    mp_hal_pin_high(pin_A15);
+    mp_hal_delay_us(1);
+    mp_hal_pin_low(pin_A15);
+}
+
+void hub_display_on(void) {
+    if (hub_display_init) {
+        return;
+    }
+    mp_hal_pin_output(pin_A15);
+    mp_hal_pin_low(pin_A15);
+    hub_display_spi_init();
+    for (int i = 0; i < 2; ++i) {
+        hub_display_latch_ctrl(0xff, 0, 0x1fffff, 0x11);
+    }
+    hub_display_tim_init();
+    hub_display_init = true;
+}
+
+void hub_display_off(void) {
+    if (!hub_display_init) {
+        return;
+    }
+    __HAL_RCC_TIM12_CLK_DISABLE();
+    __HAL_RCC_TIM12_FORCE_RESET();
+    __HAL_RCC_TIM12_RELEASE_RESET();
+    __HAL_RCC_SPI1_CLK_DISABLE();
+    __HAL_RCC_SPI1_FORCE_RESET();
+    __HAL_RCC_SPI1_RELEASE_RESET();
+    mp_hal_pin_config(pin_A5, MP_HAL_PIN_MODE_ANALOG, MP_HAL_PIN_PULL_NONE, 0);
+    mp_hal_pin_config(pin_A6, MP_HAL_PIN_MODE_ANALOG, MP_HAL_PIN_PULL_NONE, 0);
+    mp_hal_pin_config(pin_A7, MP_HAL_PIN_MODE_ANALOG, MP_HAL_PIN_PULL_NONE, 0);
+    mp_hal_pin_config(pin_A15, MP_HAL_PIN_MODE_ANALOG, MP_HAL_PIN_PULL_NONE, 0);
+    mp_hal_pin_config(pin_B15, MP_HAL_PIN_MODE_ANALOG, MP_HAL_PIN_PULL_NONE, 0);
+    hub_display_init = false;
+}
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/hub_display.h b/ports/stm32/boards/LEGO_HUB_NO6/hub_display.h
new file mode 100644
index 000000000..7623e128a
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/hub_display.h
@@ -0,0 +1,4 @@
+void hub_display_on(void);
+void hub_display_off(void);
+void hub_display_update(void);
+void hub_display_set(uint8_t led, uint16_t value);
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/mboot_memory.ld b/ports/stm32/boards/LEGO_HUB_NO6/mboot_memory.ld
new file mode 100644
index 000000000..dd914c8e8
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/mboot_memory.ld
@@ -0,0 +1,10 @@
+/*
+    Linker script fragment for mboot on an STM32xxx MCU.
+    This defines the memory sections for the bootloader to use.
+*/
+MEMORY
+{
+    FLASH_BL (rx)   : ORIGIN = 0x08008000, LENGTH = 32K
+    RAM (xrw)       : ORIGIN = 0x20000000, LENGTH = 120K
+}
+
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/mpconfigboard.h b/ports/stm32/boards/LEGO_HUB_NO6/mpconfigboard.h
new file mode 100644
index 000000000..b3e061efb
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/mpconfigboard.h
@@ -0,0 +1,141 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ * The MIT License (MIT)
+ * Copyright (c) 2021 Damien P. George
+ */
+
+#include <stdint.h>
+
+#define MICROPY_HW_BOARD_NAME                    "LEGO Technic Hub No.6"
+#define MICROPY_HW_MCU_NAME                      "STM32F413"
+
+#define MICROPY_HW_HAS_SWITCH                    (0)
+#define MICROPY_HW_HAS_FLASH                     (1)
+#define MICROPY_PY_PYB_LEGACY                    (0)
+#define MICROPY_HW_ENTER_BOOTLOADER_VIA_RESET    (0)
+#define MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE (0)
+#define MICROPY_HW_ENABLE_RTC                    (1)
+#define MICROPY_HW_ENABLE_RNG                    (1)
+#define MICROPY_HW_ENABLE_DAC                    (1)
+#define MICROPY_HW_ENABLE_USB                    (1)
+
+// HSE is 16MHz, CPU freq set to 100MHz, buses at maximum freq
+#define MICROPY_HW_CLK_PLLM                      (16)
+#define MICROPY_HW_CLK_PLLN                      (200)
+#define MICROPY_HW_CLK_PLLP                      (RCC_PLLP_DIV2)
+#define MICROPY_HW_CLK_PLLQ                      (4)
+#define MICROPY_HW_CLK_AHB_DIV                   (RCC_SYSCLK_DIV1)
+#define MICROPY_HW_CLK_APB1_DIV                  (RCC_HCLK_DIV2)
+#define MICROPY_HW_CLK_APB2_DIV                  (RCC_HCLK_DIV1)
+
+// For 2.7 to 3.6 V, 75 to 100 MHz: 3 wait states.
+#define MICROPY_HW_FLASH_LATENCY                 FLASH_LATENCY_3
+
+// UART buses
+// Bluetooth HCI
+#define MICROPY_HW_UART2_CTS                     (pin_D3)
+#define MICROPY_HW_UART2_RTS                     (pin_D4)
+#define MICROPY_HW_UART2_TX                      (pin_D5)
+#define MICROPY_HW_UART2_RX                      (pin_D6)
+// Port B
+#define MICROPY_HW_UART4_TX                      (pin_D1)
+#define MICROPY_HW_UART4_RX                      (pin_D0)
+// Port D
+#define MICROPY_HW_UART5_TX                      (pin_C12)
+#define MICROPY_HW_UART5_RX                      (pin_D2)
+// Port A
+#define MICROPY_HW_UART7_TX                      (pin_E8)
+#define MICROPY_HW_UART7_RX                      (pin_E7)
+// Port C
+#define MICROPY_HW_UART8_TX                      (pin_E1)
+#define MICROPY_HW_UART8_RX                      (pin_E0)
+// Port F
+#define MICROPY_HW_UART9_TX                      (pin_D15)
+#define MICROPY_HW_UART9_RX                      (pin_D14)
+// Port E
+#define MICROPY_HW_UART10_TX                     (pin_E3)
+#define MICROPY_HW_UART10_RX                     (pin_E2)
+
+// SPI buses
+#define MICROPY_HW_SPI1_NSS                      (pin_A4) // shared with DAC
+#define MICROPY_HW_SPI1_SCK                      (pin_A5) // shared with DAC
+#define MICROPY_HW_SPI1_MISO                     (pin_A6)
+#define MICROPY_HW_SPI1_MOSI                     (pin_A7)
+#define MICROPY_HW_SPI2_NSS                      (pin_B12)
+#define MICROPY_HW_SPI2_SCK                      (pin_B13)
+#define MICROPY_HW_SPI2_MISO                     (pin_C2)
+#define MICROPY_HW_SPI2_MOSI                     (pin_C3)
+
+// USB config
+#define MICROPY_HW_USB_VBUS_DETECT_PIN           (pin_A9)
+#define MICROPY_HW_USB_FS                        (1)
+#define MICROPY_HW_USB_MSC                       (1)
+
+// Bluetooth config
+#define MICROPY_HW_BLE_UART_ID                   (PYB_UART_2)
+#define MICROPY_HW_BLE_UART_BAUDRATE             (115200)
+#define MICROPY_HW_BLE_UART_BAUDRATE_SECONDARY   (921600)
+#define MICROPY_HW_BLE_BTSTACK_CHIPSET_INSTANCE  btstack_chipset_cc256x_instance()
+
+// SPI flash, for R/W storage
+// The first 1MiB is skipped because it's used by the built-in bootloader
+// Note: MICROPY_HW_SPIFLASH_OFFSET_BYTES must be a multiple of MP_SPIFLASH_ERASE_BLOCK_SIZE
+#define MICROPY_HW_SPIFLASH_OFFSET_BYTES         (1024 * 1024)
+#define MICROPY_HW_SPIFLASH_BLOCKMAP(bl)         ((bl) + MICROPY_HW_SPIFLASH_OFFSET_BYTES / FLASH_BLOCK_SIZE)
+#define MICROPY_HW_SPIFLASH_BLOCKMAP_EXT(bl)     ((bl) + MICROPY_HW_SPIFLASH_OFFSET_BYTES / MP_SPIFLASH_ERASE_BLOCK_SIZE)
+#define MICROPY_HW_SPIFLASH_ENABLE_CACHE         (1)
+#define MICROPY_HW_SPIFLASH_SIZE_BITS            (256 * 1024 * 1024 - MICROPY_HW_SPIFLASH_OFFSET_BYTES * 8)
+#define MICROPY_HW_SPIFLASH_CS                   (MICROPY_HW_SPI2_NSS)
+#define MICROPY_HW_SPIFLASH_SCK                  (MICROPY_HW_SPI2_SCK)
+#define MICROPY_HW_SPIFLASH_MISO                 (MICROPY_HW_SPI2_MISO)
+#define MICROPY_HW_SPIFLASH_MOSI                 (MICROPY_HW_SPI2_MOSI)
+
+// SPI flash, block device config
+extern int32_t board_bdev_ioctl(void);
+extern struct _spi_bdev_t spi_bdev;
+#define MICROPY_HW_BDEV_IOCTL(op, arg) ( \
+    (op) == BDEV_IOCTL_NUM_BLOCKS ? (MICROPY_HW_SPIFLASH_SIZE_BITS / 8 / FLASH_BLOCK_SIZE) : \
+    (op) == BDEV_IOCTL_INIT ? board_bdev_ioctl() : \
+    spi_bdev_ioctl(&spi_bdev, (op), (arg)) \
+    )
+
+// Configuration for stardard block protocol (block size FLASH_BLOCK_SIZE).
+#define MICROPY_HW_BDEV_READBLOCKS(dest, bl, n) \
+    spi_bdev_readblocks(&spi_bdev, (dest), MICROPY_HW_SPIFLASH_BLOCKMAP(bl), (n))
+#define MICROPY_HW_BDEV_WRITEBLOCKS(src, bl, n) \
+    spi_bdev_writeblocks(&spi_bdev, (src), MICROPY_HW_SPIFLASH_BLOCKMAP(bl), (n))
+
+// Configuration for extended block protocol (block size MP_SPIFLASH_ERASE_BLOCK_SIZE).
+#define MICROPY_HW_BDEV_BLOCKSIZE_EXT (MP_SPIFLASH_ERASE_BLOCK_SIZE)
+#define MICROPY_HW_BDEV_READBLOCKS_EXT(dest, bl, off, len) \
+    (spi_bdev_readblocks_raw(&spi_bdev, (dest), MICROPY_HW_SPIFLASH_BLOCKMAP_EXT(bl), (off), (len)))
+#define MICROPY_HW_BDEV_WRITEBLOCKS_EXT(src, bl, off, len) \
+    (spi_bdev_writeblocks_raw(&spi_bdev, (src), MICROPY_HW_SPIFLASH_BLOCKMAP_EXT(bl), (off), (len)))
+#define MICROPY_HW_BDEV_ERASEBLOCKS_EXT(bl, len) \
+    (spi_bdev_eraseblocks_raw(&spi_bdev, MICROPY_HW_SPIFLASH_BLOCKMAP_EXT(bl), (len)))
+
+// Board control config
+#define MICROPY_BOARD_STARTUP                    board_init
+
+/******************************************************************************/
+// Bootloader configuration
+
+#define MBOOT_LEAVE_BOOTLOADER_VIA_RESET         (0)
+
+#define MBOOT_LED1                               0
+#define MBOOT_BOARD_LED_INIT                     board_mboot_led_init
+#define MBOOT_BOARD_LED_STATE                    board_mboot_led_state
+
+#define MBOOT_BOARD_EARLY_INIT                   board_init
+#define MBOOT_BOARD_CLEANUP                      board_mboot_cleanup
+#define MBOOT_BOARD_GET_RESET_MODE               board_mboot_get_reset_mode
+
+/******************************************************************************/
+// Function declarations
+
+void board_init(void);
+void board_mboot_cleanup(int reset_mode);
+void board_mboot_led_init(void);
+void board_mboot_led_state(int led, int state);
+int board_mboot_get_reset_mode(void);
+void *btstack_chipset_cc256x_instance(void);
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/mpconfigboard.mk b/ports/stm32/boards/LEGO_HUB_NO6/mpconfigboard.mk
new file mode 100644
index 000000000..8f8695a9c
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/mpconfigboard.mk
@@ -0,0 +1,45 @@
+MCU_SERIES = f4
+CMSIS_MCU = STM32F413xx
+AF_FILE = boards/stm32f413_af.csv
+LD_FILES = boards/LEGO_HUB_NO6/stm32f413xg.ld boards/common_bl.ld
+TEXT0_ADDR = 0x08010000
+
+BOOTLOADER_DFU_USB_VID ?= 0x0694
+BOOTLOADER_DFU_USB_PID ?= 0x0008
+
+# MicroPython settings
+MICROPY_PY_BLUETOOTH ?= 1
+MICROPY_BLUETOOTH_NIMBLE ?= 0
+MICROPY_BLUETOOTH_BTSTACK ?= 1
+MICROPY_VFS_LFS2 ?= 1
+
+ifneq ($(BUILDING_MBOOT),1)
+LIB_SRC_C += lib/btstack/chipset/cc256x/btstack_chipset_cc256x.c
+endif
+
+# Bootloader settings
+MBOOT_TEXT0_ADDR = 0x08008000
+MBOOT_LD_FILES = ../boards/LEGO_HUB_NO6/mboot_memory.ld stm32_sections.ld
+
+# Backup/restore original Hub firmware
+
+HUB_FIRMWARE = lego_hub_firmware.dfu
+HUB_FIRMWARE_ADDR = $(MBOOT_TEXT0_ADDR)
+HUB_FIRMWARE_SIZE = 0xf8000
+
+backup-hub-firmware:
+	$(Q)$(DFU_UTIL) -a 0 \
+		-d $(BOOTLOADER_DFU_USB_VID):$(BOOTLOADER_DFU_USB_PID) \
+		-U $(HUB_FIRMWARE).bin \
+		-s $(HUB_FIRMWARE_ADDR):$(HUB_FIRMWARE_SIZE)
+	$(Q)$(PYTHON) $(DFU) \
+		-b $(HUB_FIRMWARE_ADDR):$(HUB_FIRMWARE).bin \
+		-D $(BOOTLOADER_DFU_USB_VID):$(BOOTLOADER_DFU_USB_PID) \
+		$(HUB_FIRMWARE)
+	$(Q)$(RM) $(HUB_FIRMWARE).bin
+	$(ECHO) "Backup created in $(HUB_FIRMWARE)"
+
+restore-hub-firmware:
+	$(Q)$(DFU_UTIL) -a 0 \
+		-d $(BOOTLOADER_DFU_USB_VID):$(BOOTLOADER_DFU_USB_PID) \
+		-D $(HUB_FIRMWARE)
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/pins.csv b/ports/stm32/boards/LEGO_HUB_NO6/pins.csv
new file mode 100644
index 000000000..9e56e2c79
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/pins.csv
@@ -0,0 +1,114 @@
+CHG_ISET_PWM,PA0
+BUTTONS_ADC,PA1
+BT_ENABLE,PA2
+CHG_IMON_ADC,PA3
+SND_DAC,PA4
+TLC_SCLK,PA5
+TLC_SOUT,PA6
+TLC_SIN,PA7
+PORTB_EN,PA8
+USB_VBUS,PA9
+PORTA_EN,PA10
+USB_DM,PA11
+USB_DP,PA12
+BAT_PWR_EN,PA13
+PORT_3V3_EN,PA14
+TLC_LAT,PA15
+BAT_NTC,PB0
+PORTF_M2,PB1
+PORTD_EN,PB2
+LSM6_SDA,PB3
+LSM6_INT1,PB4
+PORTE_EN,PB5
+PORTC_M1,PB6
+PORTC_M2,PB7
+PORTD_M1,PB8
+PORTD_M2,PB9
+LSM6_SCL,PB10
+,PB11
+,PB12
+,PB13
+,PB14
+TLC_GS_CLK,PB15
+BAT_IMON_ADC,PC0
+BAT_VMON_ADC,PC1
+,PC2
+,PC3
+CHGOK_CENBTN_3V3OK_ADC,PC4
+PORTF_EN,PC5
+PORTE_M1,PC6
+PORTE_M2,PC7
+PORTF_M1,PC8
+BT_SLOWCLK,PC9
+SND_AMP_EN,PC10
+,PC11
+PORTD_TX,PC12
+,PC13
+,PC14
+,PC15
+PORTB_RX,PD0
+PORTB_TX,PD1
+PORTD_RX,PD2
+BT_CTS,PD3
+BT_RTS,PD4
+BT_TX,PD5
+BT_RX,PD6
+,PD7
+,PD8
+,PD9
+,PD10
+,PD11
+,PD12
+,PD13
+PORTF_RX,PD14
+PORTF_TX,PD15
+PORTC_RX,PE0
+PORTC_TX,PE1
+PORTE_RX,PE2
+PORTE_TX,PE3
+,PE4
+PORTC_EN,PE5
+,PE6
+PORTA_RX,PE7
+PORTA_TX,PE8
+PORTA_M1,PE9
+PORTE_RTS,PE10
+PORTA_M2,PE11
+,PE12
+PORTB_M1,PE13
+PORTB_M2,PE14
+PORTF_RTS,PE15
+,PF0
+,PF1
+,PF2
+,PF3
+,PF4
+,PF5
+,PF6
+,PF7
+,PF8
+,PF9
+,PF10
+,PF11
+,PF12
+,PF13
+,PF14
+,PF15
+,PG0
+,PG1
+,PG2
+,PG3
+,PG4
+,PG5
+,PG6
+,PG7
+,PG8
+,PG9
+,PG10
+,PG11
+,PG12
+,PG13
+,PG14
+,PG15
+,PH0
+,PH1
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/stm32f413xg.ld b/ports/stm32/boards/LEGO_HUB_NO6/stm32f413xg.ld
new file mode 100644
index 000000000..d3c43a694
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/stm32f413xg.ld
@@ -0,0 +1,27 @@
+/*
+    GNU linker script for STM32F413xg (1MB flash, 320kB RAM)
+*/
+
+/* Specify the memory areas */
+/* FLASH_FS2 is placed before FLASH_TEXT to support 1MB and 1.5MB FLASH with common code in flashbdev.c */
+MEMORY
+{
+    FLASH (rx)      : ORIGIN = 0x08000000, LENGTH = 1024K /* entire flash */
+    FLASH_APP (rx)  : ORIGIN = 0x08010000, LENGTH = 976K
+    RAM (xrw)       : ORIGIN = 0x20000000, LENGTH = 320K /* SRAM1 + SRAM2 */
+}
+
+/* produce a link error if there is not this amount of RAM for these sections */
+_minimum_stack_size = 2K;
+_minimum_heap_size = 16K;
+
+/* Define the stack.  The stack is full descending so begins just above last byte
+   of RAM.  Note that EABI requires the stack to be 8-byte aligned for a call. */
+_estack = ORIGIN(RAM) + LENGTH(RAM) - _estack_reserve;
+_sstack = _estack - 12K; /* tunable */
+
+/* RAM extents for the garbage collector */
+_ram_start = ORIGIN(RAM);
+_ram_end = ORIGIN(RAM) + LENGTH(RAM);
+_heap_start = _ebss; /* heap starts just after statically allocated memory */
+_heap_end = _sstack;
diff --git a/ports/stm32/boards/LEGO_HUB_NO6/stm32f4xx_hal_conf.h b/ports/stm32/boards/LEGO_HUB_NO6/stm32f4xx_hal_conf.h
new file mode 100644
index 000000000..7d6344f0a
--- /dev/null
+++ b/ports/stm32/boards/LEGO_HUB_NO6/stm32f4xx_hal_conf.h
@@ -0,0 +1,19 @@
+/* This file is part of the MicroPython project, http://micropython.org/
+ * The MIT License (MIT)
+ * Copyright (c) 2019 Damien P. George
+ */
+#ifndef MICROPY_INCLUDED_STM32F4XX_HAL_CONF_H
+#define MICROPY_INCLUDED_STM32F4XX_HAL_CONF_H
+
+#include "boards/stm32f4xx_hal_conf_base.h"
+
+// Oscillator values in Hz
+#define HSE_VALUE (16000000)
+#define LSE_VALUE (32768)
+#define EXTERNAL_CLOCK_VALUE (12288000)
+
+// Oscillator timeouts in ms
+#define HSE_STARTUP_TIMEOUT (100)
+#define LSE_STARTUP_TIMEOUT (5000)
+
+#endif // MICROPY_INCLUDED_STM32F4XX_HAL_CONF_H
diff --git a/ports/stm32/boards/NUCLEO_F091RC/mpconfigboard.h b/ports/stm32/boards/NUCLEO_F091RC/mpconfigboard.h
index 7333dcd0c..a0bff5996 100644
--- a/ports/stm32/boards/NUCLEO_F091RC/mpconfigboard.h
+++ b/ports/stm32/boards/NUCLEO_F091RC/mpconfigboard.h
@@ -3,6 +3,7 @@
 
 #define MICROPY_EMIT_THUMB          (0)
 #define MICROPY_EMIT_INLINE_THUMB   (0)
+#define MICROPY_OPT_COMPUTED_GOTO   (0)
 #define MICROPY_PY_USOCKET          (0)
 #define MICROPY_PY_NETWORK          (0)
 #define MICROPY_PY_STM              (0)
diff --git a/ports/stm32/boards/NUCLEO_F439ZI/mpconfigboard.h b/ports/stm32/boards/NUCLEO_F439ZI/mpconfigboard.h
new file mode 100644
index 000000000..010e3b1f5
--- /dev/null
+++ b/ports/stm32/boards/NUCLEO_F439ZI/mpconfigboard.h
@@ -0,0 +1,81 @@
+#define MICROPY_HW_BOARD_NAME       "NUCLEO-F439ZI"
+#define MICROPY_HW_MCU_NAME         "STM32F439ZIT6"
+
+#define MICROPY_HW_HAS_SWITCH       (1)
+#define MICROPY_HW_HAS_FLASH        (1)
+#define MICROPY_HW_ENABLE_RNG       (1)
+#define MICROPY_HW_ENABLE_RTC       (1)
+#define MICROPY_HW_ENABLE_USB       (1)
+
+// HSE is 8MHz from ST-LINK, in bypass mode, run SYSCLK at 168MHz
+#define MICROPY_HW_CLK_USE_BYPASS   (1)
+#define MICROPY_HW_CLK_PLLM         (8)
+#define MICROPY_HW_CLK_PLLN         (336)
+#define MICROPY_HW_CLK_PLLP         (RCC_PLLP_DIV2)
+#define MICROPY_HW_CLK_PLLQ         (7)
+#define MICROPY_HW_FLASH_LATENCY    FLASH_LATENCY_5
+
+// The board has a 32768Hz crystal for LSE
+#define MICROPY_HW_RTC_USE_LSE      (1)
+#define MICROPY_HW_RTC_USE_US       (1)
+
+// UART config
+#define MICROPY_HW_UART2_TX         (pin_D5)
+#define MICROPY_HW_UART2_RX         (pin_D6)
+#define MICROPY_HW_UART2_RTS        (pin_D4)
+#define MICROPY_HW_UART2_CTS        (pin_D3)
+#define MICROPY_HW_UART3_TX         (pin_D8)
+#define MICROPY_HW_UART3_RX         (pin_D9)
+#define MICROPY_HW_UART6_TX         (pin_G14)
+#define MICROPY_HW_UART6_RX         (pin_G9)
+#define MICROPY_HW_UART_REPL        PYB_UART_3
+#define MICROPY_HW_UART_REPL_BAUD   115200
+
+// I2C buses
+#define MICROPY_HW_I2C1_SCL         (pin_B8)
+#define MICROPY_HW_I2C1_SDA         (pin_B9)
+#define MICROPY_HW_I2C2_SCL         (pin_F1)
+#define MICROPY_HW_I2C2_SDA         (pin_F0)
+
+// SPI buses
+#define MICROPY_HW_SPI1_NSS         (pin_D14)
+#define MICROPY_HW_SPI1_SCK         (pin_A5)
+#define MICROPY_HW_SPI1_MISO        (pin_A6)
+#define MICROPY_HW_SPI1_MOSI        (pin_A7)
+#define MICROPY_HW_SPI3_NSS         (pin_A4)
+#define MICROPY_HW_SPI3_SCK         (pin_B3)
+#define MICROPY_HW_SPI3_MISO        (pin_B4)
+#define MICROPY_HW_SPI3_MOSI        (pin_B5)
+
+// CAN buses
+#define MICROPY_HW_CAN1_TX          (pin_D1)
+#define MICROPY_HW_CAN1_RX          (pin_D0)
+
+// USRSW is pulled low; pressing the button makes the input go high.
+#define MICROPY_HW_USRSW_PIN        (pin_C13)
+#define MICROPY_HW_USRSW_PULL       (GPIO_NOPULL)
+#define MICROPY_HW_USRSW_EXTI_MODE  (GPIO_MODE_IT_RISING)
+#define MICROPY_HW_USRSW_PRESSED    (1)
+
+// LEDs
+#define MICROPY_HW_LED1             (pin_B0) // green
+#define MICROPY_HW_LED2             (pin_B7) // blue
+#define MICROPY_HW_LED3             (pin_B14) // red
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
+
+// USB config (CN13 - USB OTG FS)
+#define MICROPY_HW_USB_FS              (1)
+#define MICROPY_HW_USB_VBUS_DETECT_PIN (pin_A9)
+#define MICROPY_HW_USB_OTG_ID_PIN      (pin_A10)
+
+// Ethernet via RMII
+#define MICROPY_HW_ETH_MDC          (pin_C1)
+#define MICROPY_HW_ETH_MDIO         (pin_A2)
+#define MICROPY_HW_ETH_RMII_REF_CLK (pin_A1)
+#define MICROPY_HW_ETH_RMII_CRS_DV  (pin_A7)
+#define MICROPY_HW_ETH_RMII_RXD0    (pin_C4)
+#define MICROPY_HW_ETH_RMII_RXD1    (pin_C5)
+#define MICROPY_HW_ETH_RMII_TX_EN   (pin_G11)
+#define MICROPY_HW_ETH_RMII_TXD0    (pin_G13)
+#define MICROPY_HW_ETH_RMII_TXD1    (pin_B13)
diff --git a/ports/stm32/boards/NUCLEO_F439ZI/mpconfigboard.mk b/ports/stm32/boards/NUCLEO_F439ZI/mpconfigboard.mk
new file mode 100644
index 000000000..52702b511
--- /dev/null
+++ b/ports/stm32/boards/NUCLEO_F439ZI/mpconfigboard.mk
@@ -0,0 +1,11 @@
+MCU_SERIES = f4
+CMSIS_MCU = STM32F439xx
+AF_FILE = boards/stm32f439_af.csv
+LD_FILES = boards/stm32f439.ld boards/common_ifs.ld
+TEXT0_ADDR = 0x08000000
+TEXT1_ADDR = 0x08020000
+
+# MicroPython settings
+MICROPY_PY_LWIP = 1
+MICROPY_PY_USSL = 1
+MICROPY_SSL_MBEDTLS = 1
diff --git a/ports/stm32/boards/NUCLEO_F439ZI/pins.csv b/ports/stm32/boards/NUCLEO_F439ZI/pins.csv
new file mode 100644
index 000000000..cea3678ed
--- /dev/null
+++ b/ports/stm32/boards/NUCLEO_F439ZI/pins.csv
@@ -0,0 +1,129 @@
+,PA0
+,PA1
+,PA2
+,PA3
+,PA4
+,PA5
+,PA6
+,PA7
+,PA8
+,PA9
+,PA10
+,PA11
+,PA12
+,PA13
+,PA14
+,PA15
+,PB0
+,PB1
+,PB2
+,PB3
+,PB4
+,PB5
+,PB6
+,PB7
+,PB8
+,PB9
+,PB10
+,PB11
+,PB12
+,PB13
+,PB14
+,PB15
+,PC0
+,PC1
+,PC2
+,PC3
+,PC4
+,PC5
+,PC6
+,PC7
+,PC8
+,PC9
+,PC10
+,PC11
+,PC12
+,PC13
+,PC14
+,PC15
+,PD0
+,PD1
+,PD2
+,PD3
+,PD4
+,PD5
+,PD6
+,PD7
+,PD8
+,PD9
+,PD10
+,PD11
+,PD12
+,PD13
+,PD14
+,PD15
+,PE0
+,PE1
+,PE2
+,PE3
+,PE4
+,PE5
+,PE6
+,PE7
+,PE8
+,PE9
+,PE10
+,PE11
+,PE12
+,PE13
+,PE14
+,PE15
+,PF0
+,PF1
+,PF2
+,PF3
+,PF4
+,PF5
+,PF6
+,PF7
+,PF8
+,PF9
+,PF10
+,PF11
+,PF12
+,PF13
+,PF14
+,PF15
+,PG0
+,PG1
+,PG2
+,PG3
+,PG4
+,PG5
+,PG6
+,PG7
+,PG8
+,PG9
+,PG10
+,PG11
+,PG12
+,PG13
+,PG14
+,PG15
+SW,PC13
+LED_GREEN,PB0
+LED_BLUE,PB7
+LED_RED,PB14
+USB_VBUS,PA9
+USB_ID,PA10
+USB_DM,PA11
+USB_DP,PA12
+ETH_MDC,PC1
+ETH_MDIO,PA2
+ETH_RMII_REF_CLK,PA1
+ETH_RMII_CRS_DV,PA7
+ETH_RMII_RXD0,PC4
+ETH_RMII_RXD1,PC5
+ETH_RMII_TX_EN,PG11
+ETH_RMII_TXD0,PG13
+ETH_RMII_TXD1,PB13
diff --git a/ports/stm32/boards/NUCLEO_F439ZI/stm32f4xx_hal_conf.h b/ports/stm32/boards/NUCLEO_F439ZI/stm32f4xx_hal_conf.h
new file mode 100644
index 000000000..de19251e0
--- /dev/null
+++ b/ports/stm32/boards/NUCLEO_F439ZI/stm32f4xx_hal_conf.h
@@ -0,0 +1,19 @@
+/* This file is part of the MicroPython project, http://micropython.org/
+ * The MIT License (MIT)
+ * Copyright (c) 2019 Damien P. George
+ */
+#ifndef MICROPY_INCLUDED_STM32F4XX_HAL_CONF_H
+#define MICROPY_INCLUDED_STM32F4XX_HAL_CONF_H
+
+#include "boards/stm32f4xx_hal_conf_base.h"
+
+// Oscillator values in Hz
+#define HSE_VALUE (8000000)
+#define LSE_VALUE (32768)
+#define EXTERNAL_CLOCK_VALUE (12288000)
+
+// Oscillator timeouts in ms
+#define HSE_STARTUP_TIMEOUT (100)
+#define LSE_STARTUP_TIMEOUT (5000)
+
+#endif // MICROPY_INCLUDED_STM32F4XX_HAL_CONF_H
diff --git a/ports/stm32/boards/NUCLEO_F446RE/mpconfigboard.h b/ports/stm32/boards/NUCLEO_F446RE/mpconfigboard.h
index 27845b33a..681231578 100644
--- a/ports/stm32/boards/NUCLEO_F446RE/mpconfigboard.h
+++ b/ports/stm32/boards/NUCLEO_F446RE/mpconfigboard.h
@@ -25,8 +25,8 @@
 #define MICROPY_HW_UART_REPL_BAUD   115200
 
 // I2C buses
-#define MICROPY_HW_I2C1_SCL (pin_B6)        // Arduino D10, pin 17 on CN10
-#define MICROPY_HW_I2C1_SDA (pin_B7)        //              pin 21 on CN7
+#define MICROPY_HW_I2C1_SCL (pin_B8)        // Arduino D15, pin 3 on CN10
+#define MICROPY_HW_I2C1_SDA (pin_B9)        // Arduino D14, pin 5 on CN10
 #define MICROPY_HW_I2C2_SCL (pin_B10)       // Arduino D6,  pin 25 on CN10
 #define MICROPY_HW_I2C2_SDA (pin_B3)        // Arduino D3,  pin 31 on CN10
 #define MICROPY_HW_I2C3_SCL (pin_A8)        // Arduino D7,  pin 23 on CN10
@@ -53,6 +53,12 @@
 #define MICROPY_HW_SPI4_MISO    (pin_A1)    //              pin 30 on CN7
 #define MICROPY_HW_SPI4_MOSI    (pin_A11)   //              pin 14 on CN10
 
+// CAN buses
+#define MICROPY_HW_CAN1_TX      (pin_B9)    //              pin 5 on CN10
+#define MICROPY_HW_CAN1_RX      (pin_B8)    //              pin 3 on CN10
+#define MICROPY_HW_CAN2_TX      (pin_B6)    //              pin 17 on CN10
+#define MICROPY_HW_CAN2_RX      (pin_B5)    //              pin 29 on CN10
+
 // USRSW is pulled low. Pressing the button makes the input go high.
 #define MICROPY_HW_USRSW_PIN        (pin_C13)
 #define MICROPY_HW_USRSW_PULL       (GPIO_NOPULL)
diff --git a/ports/stm32/boards/NUCLEO_H743ZI/board_init.c b/ports/stm32/boards/NUCLEO_H743ZI/board_init.c
index 04149c37b..40f3730cc 100644
--- a/ports/stm32/boards/NUCLEO_H743ZI/board_init.c
+++ b/ports/stm32/boards/NUCLEO_H743ZI/board_init.c
@@ -2,7 +2,6 @@
 
 void NUCLEO_H743ZI_board_early_init(void) {
     // Turn off the USB switch
-    #define USB_PowerSwitchOn pin_G6
-    mp_hal_pin_output(USB_PowerSwitchOn);
-    mp_hal_pin_low(USB_PowerSwitchOn);
+    mp_hal_pin_output(pyb_pin_OTG_FS_POWER);
+    mp_hal_pin_low(pyb_pin_OTG_FS_POWER);
 }
diff --git a/ports/stm32/boards/NUCLEO_H743ZI2/board_init.c b/ports/stm32/boards/NUCLEO_H743ZI2/board_init.c
new file mode 100644
index 000000000..04caaaca9
--- /dev/null
+++ b/ports/stm32/boards/NUCLEO_H743ZI2/board_init.c
@@ -0,0 +1 @@
+#include "boards/NUCLEO_H743ZI/board_init.c"
diff --git a/ports/stm32/boards/NUCLEO_H743ZI2/mpconfigboard.h b/ports/stm32/boards/NUCLEO_H743ZI2/mpconfigboard.h
new file mode 100644
index 000000000..22060277d
--- /dev/null
+++ b/ports/stm32/boards/NUCLEO_H743ZI2/mpconfigboard.h
@@ -0,0 +1,25 @@
+#include "boards/NUCLEO_H743ZI/mpconfigboard.h"
+
+#undef MICROPY_HW_BOARD_NAME
+#define MICROPY_HW_BOARD_NAME       "NUCLEO_H743ZI2"
+
+// The board has an external 32kHz crystal attached
+#undef MICROPY_HW_RTC_USE_LSE
+#define MICROPY_HW_RTC_USE_LSE      (1)
+
+// There is no external HS crystal.
+// JP1 STLNK_RST will disable the incoming 8MHz clock
+// since it is derived from the STLINK's MCO output
+#undef MICROPY_HW_CLK_USE_BYPASS
+#define MICROPY_HW_CLK_USE_BYPASS   (1)
+
+#undef MICROPY_HW_LED2
+#define MICROPY_HW_LED2             (pin_E1)    // yellow
+
+// only when mboot is used
+// Define the user button for entering mboot
+#if defined(USE_MBOOT)
+#define MBOOT_BOOTPIN_PIN (pin_C13)
+#define MBOOT_BOOTPIN_PULL (MP_HAL_PIN_PULL_DOWN)
+#define MBOOT_BOOTPIN_ACTIVE (1)
+#endif
diff --git a/ports/stm32/boards/NUCLEO_H743ZI2/mpconfigboard.mk b/ports/stm32/boards/NUCLEO_H743ZI2/mpconfigboard.mk
new file mode 100644
index 000000000..e49a4d0d6
--- /dev/null
+++ b/ports/stm32/boards/NUCLEO_H743ZI2/mpconfigboard.mk
@@ -0,0 +1 @@
+include boards/NUCLEO_H743ZI/mpconfigboard.mk
diff --git a/ports/stm32/boards/NUCLEO_H743ZI2/pins.csv b/ports/stm32/boards/NUCLEO_H743ZI2/pins.csv
new file mode 100644
index 000000000..450d6e432
--- /dev/null
+++ b/ports/stm32/boards/NUCLEO_H743ZI2/pins.csv
@@ -0,0 +1,130 @@
+A0,PA3
+A1,PC0
+A2,PC3
+A3,PB1
+A4,PC2
+A5,PF10
+A6,PF4
+A7,PF5
+A8,PF6
+D0,PB7
+D1,PB6
+D2,PG14
+D3,PE13
+D4,PE14
+D5,PE11
+D6,PE9
+D7,PG12
+D8,PF3
+D9,PD15
+D10,PD14
+D11,PB5
+D12,PA6
+D13,PA7
+D14,PB9
+D15,PB8
+D16,PC6
+D17,PB15
+D18,PB13
+D19,PB12
+D20,PA15
+D21,PC7
+D22,PB5
+D23,PB3
+D24,PA4
+D25,PB4
+D26,PG6
+D27,PB2
+D28,PD13
+D29,PD12
+D30,PD11
+D31,PE2
+D32,PA0
+D33,PB0
+D34,PE0
+D35,PB11
+D36,PB10
+D37,PE15
+D38,PE6
+D39,PE12
+D40,PE10
+D41,PE7
+D42,PE8
+D43,PC8
+D44,PC9
+D45,PC10
+D46,PC11
+D47,PC12
+D48,PD2
+D49,PG2
+D50,PG3
+D51,PD7
+D52,PD6
+D53,PD5
+D54,PD4
+D55,PD3
+D56,PE2
+D57,PE4
+D58,PE5
+D59,PE6
+D60,PE3
+D61,PF8
+D62,PF7
+D63,PF9
+D64,PG1
+D65,PG0
+D66,PD1
+D67,PD0
+D68,PF0
+D69,PF1
+D70,PF2
+D71,PE9
+D72,PB2
+DAC1,PA4
+DAC2,PA5
+LED1,PB0
+LED2,PE1
+LED3,PB14
+SW,PC13
+I2C1_SDA,PB9
+I2C1_SCL,PB8
+I2C2_SDA,PF0
+I2C2_SCL,PF1
+I2C4_SCL,PF14
+I2C4_SDA,PF15
+SD_D0,PC8
+SD_D1,PC9
+SD_D2,PC10
+SD_D3,PC11
+SD_CMD,PD2
+SD_CK,PC12
+SD_SW,PG2
+OTG_FS_POWER,PD10
+OTG_FS_OVER_CURRENT,PG7
+USB_VBUS,PA9
+USB_ID,PA10
+USB_DM,PA11
+USB_DP,PA12
+UART2_TX,PD5
+UART2_RX,PD6
+UART2_RTS,PD4
+UART2_CTS,PD3
+UART3_TX,PD8
+UART3_RX,PD9
+UART5_TX,PB6
+UART5_RX,PB12
+UART6_TX,PC6
+UART6_RX,PC7
+UART7_TX,PF7
+UART7_RX,PF6
+UART8_TX,PE1
+UART8_RX,PE0
+ETH_MDC,PC1
+ETH_MDIO,PA2
+ETH_RMII_REF_CLK,PA1
+ETH_RMII_CRS_DV,PA7
+ETH_RMII_RXD0,PC4
+ETH_RMII_RXD1,PC5
+ETH_RMII_TX_EN,PG11
+ETH_RMII_TXD0,PG13
+ETH_RMII_TXD1,PB13
diff --git a/ports/stm32/boards/NUCLEO_H743ZI2/stm32h7xx_hal_conf.h b/ports/stm32/boards/NUCLEO_H743ZI2/stm32h7xx_hal_conf.h
new file mode 100644
index 000000000..61f202e62
--- /dev/null
+++ b/ports/stm32/boards/NUCLEO_H743ZI2/stm32h7xx_hal_conf.h
@@ -0,0 +1 @@
+#include "boards/NUCLEO_H743ZI/stm32h7xx_hal_conf.h"
diff --git a/ports/stm32/boards/NUCLEO_L073RZ/mpconfigboard.h b/ports/stm32/boards/NUCLEO_L073RZ/mpconfigboard.h
index b7f7bc4c8..c8c809eb4 100644
--- a/ports/stm32/boards/NUCLEO_L073RZ/mpconfigboard.h
+++ b/ports/stm32/boards/NUCLEO_L073RZ/mpconfigboard.h
@@ -7,6 +7,7 @@
 
 #define MICROPY_EMIT_THUMB          (0)
 #define MICROPY_EMIT_INLINE_THUMB   (0)
+#define MICROPY_OPT_COMPUTED_GOTO   (0)
 #define MICROPY_PY_BUILTINS_COMPLEX (0)
 #define MICROPY_PY_GENERATOR_PEND_THROW (0)
 #define MICROPY_PY_MATH             (0)
@@ -19,6 +20,8 @@
 #define MICROPY_PY_UHEAPQ           (0)
 #define MICROPY_PY_UTIMEQ           (0)
 
+#define MICROPY_PY_MACHINE_BITSTREAM (0)
+
 #define MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE (0)
 #define MICROPY_HW_ENABLE_RTC       (1)
 #define MICROPY_HW_ENABLE_ADC       (0)
diff --git a/ports/stm32/boards/NUCLEO_L432KC/mpconfigboard.h b/ports/stm32/boards/NUCLEO_L432KC/mpconfigboard.h
index 0f1134491..8b3a8f38b 100644
--- a/ports/stm32/boards/NUCLEO_L432KC/mpconfigboard.h
+++ b/ports/stm32/boards/NUCLEO_L432KC/mpconfigboard.h
@@ -67,5 +67,5 @@
 #define MICROPY_HW_USB_FS           (MICROPY_HW_ENABLE_USB)
 #define MICROPY_HW_USB_MSC          (0)
 #define MICROPY_HW_USB_HID          (0)
-#define USBD_CDC_RX_DATA_SIZE       (256)
-#define USBD_CDC_TX_DATA_SIZE       (256)
+#define MICROPY_HW_USB_CDC_RX_DATA_SIZE (256)
+#define MICROPY_HW_USB_CDC_TX_DATA_SIZE (256)
diff --git a/ports/stm32/boards/NUCLEO_WB55/mpconfigboard.h b/ports/stm32/boards/NUCLEO_WB55/mpconfigboard.h
index 179369d94..a7473b9d6 100644
--- a/ports/stm32/boards/NUCLEO_WB55/mpconfigboard.h
+++ b/ports/stm32/boards/NUCLEO_WB55/mpconfigboard.h
@@ -59,8 +59,8 @@
 
 // USB config
 #define MICROPY_HW_USB_FS           (1)
-#define USBD_CDC_RX_DATA_SIZE       (512)
-#define USBD_CDC_TX_DATA_SIZE       (512)
+#define MICROPY_HW_USB_CDC_RX_DATA_SIZE (512)
+#define MICROPY_HW_USB_CDC_TX_DATA_SIZE (512)
 
 // Bluetooth config
 #define MICROPY_HW_BLE_UART_ID       (0)
diff --git a/ports/stm32/boards/PYBD_SF2/mpconfigboard.h b/ports/stm32/boards/PYBD_SF2/mpconfigboard.h
index 48b3ee3eb..ed76b3f97 100644
--- a/ports/stm32/boards/PYBD_SF2/mpconfigboard.h
+++ b/ports/stm32/boards/PYBD_SF2/mpconfigboard.h
@@ -40,6 +40,7 @@
 #define MICROPY_HW_ENABLE_SDCARD    (1)
 #define MICROPY_HW_ENABLE_MMCARD    (1)
 #define MICROPY_HW_ENABLE_RF_SWITCH (1)
+#define MICROPY_HW_ENABLE_I2S       (1)
 
 #define MICROPY_BOARD_EARLY_INIT    board_early_init
 #define MICROPY_BOARD_ENTER_STOP    board_sleep(1);
@@ -146,6 +147,10 @@ extern struct _spi_bdev_t spi_bdev2;
 #define MICROPY_HW_SPI3_MISO        (pyb_pin_W50)
 #define MICROPY_HW_SPI3_MOSI        (pyb_pin_W46)
 
+// I2S buses
+#define MICROPY_HW_I2S1             (1)
+#define MICROPY_HW_I2S2             (1)
+
 // CAN buses
 #define MICROPY_HW_CAN1_NAME        "X"
 #define MICROPY_HW_CAN1_TX          (pyb_pin_X10)
diff --git a/ports/stm32/boards/PYBV10/mpconfigboard.h b/ports/stm32/boards/PYBV10/mpconfigboard.h
index 52382f44d..50ef3ae26 100644
--- a/ports/stm32/boards/PYBV10/mpconfigboard.h
+++ b/ports/stm32/boards/PYBV10/mpconfigboard.h
@@ -11,6 +11,7 @@
 #define MICROPY_HW_ENABLE_DAC       (1)
 #define MICROPY_HW_ENABLE_USB       (1)
 #define MICROPY_HW_ENABLE_SDCARD    (1)
+#define MICROPY_HW_ENABLE_I2S       (1)
 
 // HSE is 8MHz
 #define MICROPY_HW_CLK_PLLM (8)
@@ -64,6 +65,9 @@
 #define MICROPY_HW_SPI2_MISO (pin_B14) // Y7
 #define MICROPY_HW_SPI2_MOSI (pin_B15) // Y8
 
+// I2S buses
+#define MICROPY_HW_I2S2      (1)
+
 // CAN buses
 #define MICROPY_HW_CAN1_NAME "YA"
 #define MICROPY_HW_CAN1_TX   (pin_B9) // Y4
diff --git a/ports/stm32/boards/PYBV11/mpconfigboard.h b/ports/stm32/boards/PYBV11/mpconfigboard.h
index 8e8469404..aec83d134 100644
--- a/ports/stm32/boards/PYBV11/mpconfigboard.h
+++ b/ports/stm32/boards/PYBV11/mpconfigboard.h
@@ -11,6 +11,7 @@
 #define MICROPY_HW_ENABLE_DAC       (1)
 #define MICROPY_HW_ENABLE_USB       (1)
 #define MICROPY_HW_ENABLE_SDCARD    (1)
+#define MICROPY_HW_ENABLE_I2S       (1)
 
 // HSE is 12MHz
 #define MICROPY_HW_CLK_PLLM (12)
@@ -64,6 +65,9 @@
 #define MICROPY_HW_SPI2_MISO (pin_B14) // Y7
 #define MICROPY_HW_SPI2_MOSI (pin_B15) // Y8
 
+// I2S buses
+#define MICROPY_HW_I2S2      (1)
+
 // CAN buses
 #define MICROPY_HW_CAN1_NAME "YA"
 #define MICROPY_HW_CAN1_TX   (pin_B9) // Y4
diff --git a/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/bdev.c b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/bdev.c
new file mode 100644
index 000000000..18b5b85b1
--- /dev/null
+++ b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/bdev.c
@@ -0,0 +1,28 @@
+#include "storage.h"
+
+#if !MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+
+// External SPI flash uses standard SPI interface
+
+STATIC const mp_soft_spi_obj_t soft_spi_bus = {
+    .delay_half = MICROPY_HW_SOFTSPI_MIN_DELAY,
+    .polarity = 0,
+    .phase = 0,
+    .sck = MICROPY_HW_SPIFLASH_SCK,
+    .mosi = MICROPY_HW_SPIFLASH_MOSI,
+    .miso = MICROPY_HW_SPIFLASH_MISO,
+};
+
+STATIC mp_spiflash_cache_t spi_bdev_cache;
+
+const mp_spiflash_config_t spiflash_config = {
+    .bus_kind = MP_SPIFLASH_BUS_SPI,
+    .bus.u_spi.cs = MICROPY_HW_SPIFLASH_CS,
+    .bus.u_spi.data = (void*)&soft_spi_bus,
+    .bus.u_spi.proto = &mp_soft_spi_proto,
+    .cache = &spi_bdev_cache,
+};
+
+spi_bdev_t spi_bdev;
+
+#endif
diff --git a/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/board_init.c b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/board_init.c
new file mode 100644
index 000000000..0184bc820
--- /dev/null
+++ b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/board_init.c
@@ -0,0 +1,11 @@
+#include "py/mphal.h"
+
+void board_early_init(void) {
+
+#if !MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+    // set external SPI flash CS pin high
+    mp_hal_pin_output(MICROPY_HW_SPIFLASH_CS);
+    mp_hal_pin_write(MICROPY_HW_SPIFLASH_CS, 1);
+#endif
+
+}
diff --git a/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/mpconfigboard.h b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/mpconfigboard.h
new file mode 100644
index 000000000..0c451a4db
--- /dev/null
+++ b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/mpconfigboard.h
@@ -0,0 +1,100 @@
+// The Sparkfun MicroMod spec uses a zero-based peripheral numbering scheme.
+// In cases where the 0th peripheral is the default, the "0" is omitted from
+// the name (e.g. "I2C" instead of "I2C0").
+//
+// Note: UART (UART0) is not present in the edge connector pinout because the
+// primary debug serial port is exposed as a virtual serial port over USB,
+// i.e. Serial.print() should print over USB VCP, not UART_TX1.
+//
+// For more details, see https://www.sparkfun.com/micromod#tech-specs
+
+#define MICROPY_HW_BOARD_NAME "SparkFun STM32 MicroMod Processor"
+#define MICROPY_HW_MCU_NAME "STM32F405RG"
+
+// 1 = use STM32 internal flash (1 MByte)
+// 0 = use onboard external SPI flash (16 MByte)
+#define MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE (0)
+
+#define MICROPY_HW_HAS_FLASH (1)
+#define MICROPY_HW_ENABLE_RNG (1)
+#define MICROPY_HW_ENABLE_RTC (1)
+#define MICROPY_HW_ENABLE_DAC (1)
+#define MICROPY_HW_ENABLE_USB (1)
+
+// External SPI Flash config
+#if !MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+
+// 128 Mbit (16 MByte) external SPI flash
+#define MICROPY_HW_SPIFLASH_SIZE_BITS (128 * 1024 * 1024)
+
+#define MICROPY_HW_SPIFLASH_CS (pin_C3)
+#define MICROPY_HW_SPIFLASH_SCK (pin_C10)
+#define MICROPY_HW_SPIFLASH_MOSI (pin_C12)
+#define MICROPY_HW_SPIFLASH_MISO (pin_C11)
+
+#define MICROPY_BOARD_EARLY_INIT board_early_init
+void board_early_init(void);
+
+extern const struct _mp_spiflash_config_t spiflash_config;
+extern struct _spi_bdev_t spi_bdev;
+#define MICROPY_HW_SPIFLASH_ENABLE_CACHE (1)
+#define MICROPY_HW_BDEV_IOCTL(op, arg) ( \
+    (op) == BDEV_IOCTL_NUM_BLOCKS ? (MICROPY_HW_SPIFLASH_SIZE_BITS / 8 / FLASH_BLOCK_SIZE) : \
+    (op) == BDEV_IOCTL_INIT ? spi_bdev_ioctl(&spi_bdev, (op), (uint32_t)&spiflash_config) : \
+    spi_bdev_ioctl(&spi_bdev, (op), (arg)) \
+)
+#define MICROPY_HW_BDEV_READBLOCKS(dest, bl, n) spi_bdev_readblocks(&spi_bdev, (dest), (bl), (n))
+#define MICROPY_HW_BDEV_WRITEBLOCKS(src, bl, n) spi_bdev_writeblocks(&spi_bdev, (src), (bl), (n))
+#define MICROPY_HW_BDEV_SPIFLASH_EXTENDED (&spi_bdev) // for extended block protocol
+
+#endif // !MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
+
+// STM32 HSE config
+// The module has a 12 MHz crystal for the HSE oscillator.
+#define MICROPY_HW_CLK_PLLM (12)
+#define MICROPY_HW_CLK_PLLN (336)
+#define MICROPY_HW_CLK_PLLP (RCC_PLLP_DIV2)
+#define MICROPY_HW_CLK_PLLQ (7)
+#define MICROPY_HW_CLK_LAST_FREQ (1)
+
+// STM32 LSE config
+// The module has a 32.768 kHz crystal for the LSE (RTC).
+#define MICROPY_HW_RTC_USE_LSE (1)
+#define MICROPY_HW_RTC_USE_US (0)
+#define MICROPY_HW_RTC_USE_CALOUT (1)
+
+// UART1 config (MicroMod UART1)
+#define MICROPY_HW_UART1_NAME "UART1"
+#define MICROPY_HW_UART1_TX (pin_A2)
+#define MICROPY_HW_UART1_RX (pin_A3)
+
+// CAN1 config (MicroMod CAN)
+#define MICROPY_HW_CAN1_NAME "CAN"
+#define MICROPY_HW_CAN1_TX (pin_B9)
+#define MICROPY_HW_CAN1_RX (pin_B8)
+
+// I2C1 config (MicroMod I2C)
+#define MICROPY_HW_I2C1_NAME "I2C"
+#define MICROPY_HW_I2C1_SCL (pin_B10)
+#define MICROPY_HW_I2C1_SDA (pin_B11)
+
+// I2C2 config (MicroMod I2C1)
+#define MICROPY_HW_I2C2_NAME "I2C1"
+#define MICROPY_HW_I2C2_SCL (pin_B6)
+#define MICROPY_HW_I2C2_SDA (pin_B7)
+
+// SPI1 config (MicroMod SPI)
+#define MICROPY_HW_SPI1_NAME "SPI"
+#define MICROPY_HW_SPI1_NSS (pin_C4)
+#define MICROPY_HW_SPI1_SCK (pin_A5)
+#define MICROPY_HW_SPI1_MISO (pin_A6)
+#define MICROPY_HW_SPI1_MOSI (pin_A7)
+
+// LED1 config
+// The module has a single blue status LED.
+#define MICROPY_HW_LED1 (pin_A15)
+#define MICROPY_HW_LED_ON(pin) (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin) (mp_hal_pin_low(pin))
+
+// USB device config
+#define MICROPY_HW_USB_FS (1)
diff --git a/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/mpconfigboard.mk b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/mpconfigboard.mk
new file mode 100644
index 000000000..cb78a7846
--- /dev/null
+++ b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/mpconfigboard.mk
@@ -0,0 +1,16 @@
+MCU_SERIES = f4
+CMSIS_MCU = STM32F405xx
+AF_FILE = boards/stm32f405_af.csv
+ifeq ($(USE_MBOOT),1)
+# When using Mboot all the text goes together after the filesystem
+LD_FILES = boards/stm32f405.ld boards/common_blifs.ld
+TEXT0_ADDR = 0x08020000
+else
+# When not using Mboot the ISR text goes first, then the rest after the filesystem
+LD_FILES = boards/stm32f405.ld boards/common_ifs.ld
+TEXT0_ADDR = 0x08000000
+TEXT1_ADDR = 0x08020000
+endif
+
+# MicroPython settings
+MICROPY_VFS_LFS2 = 1
diff --git a/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/pins.csv b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/pins.csv
new file mode 100644
index 000000000..5e77de300
--- /dev/null
+++ b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/pins.csv
@@ -0,0 +1,57 @@
+G2,PA0
+BUS2,PA0
+BATT_SENSE,PA1
+UART_TX1,PA2
+UART_RX1,PA3
+AUD_LRCLK,PA4
+SPI_SCK,PA5
+SPI_MISO,PA6
+SPI_CIPO,PA6
+SPI_MOSI,PA7
+SPI_COPI,PA7
+G1,PA8
+BUS1,PA8
+USB_DN,PA11
+USB_DP,PA12
+SWDIO,PA13
+SWDCK,PA14
+STATUS_LED,PA15
+A1,PB0
+I2C_INT,PB1
+AUD_BCLK,PB3
+AUD_OUT,PB4
+AUD_IN,PB5
+I2C_SCL1,PB6
+I2C_SDA1,PB7
+CAN_RX,PB8
+CAN_TX,PB9
+I2C_SCL,PB10
+I2C_SDA,PB11
+USB_HOST_ID,PB12
+G11,PB12
+USB_HOST_VBUS,PB13
+G10,PB13
+USB_HOST_DN,PB14
+USB_HOST_DP,PB15
+D0,PC0
+D1,PC1
+G6,PC2
+BUS6,PC2
+SPI_FLASH_CS,PC3
+SPI_CS,PC4
+A0,PC5
+PWM0,PC6
+PWM1,PC7
+G3,PC8
+BUS3,PC8
+G4,PC9
+BUS4,PC9
+SPI_FLASH_SCK,PC10
+SPI_FLASH_MISO,PC11
+SPI_FLASH_MOSI,PC12
+G5,PC13
+BUS5,PC13
+OSC32_IN,PC14
+OSC32_OUT,PC15
+G0,PD2
+BUS0,PD2
diff --git a/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/stm32f4xx_hal_conf.h b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/stm32f4xx_hal_conf.h
new file mode 100644
index 000000000..9719157e5
--- /dev/null
+++ b/ports/stm32/boards/SPARKFUN_MICROMOD_STM32/stm32f4xx_hal_conf.h
@@ -0,0 +1,19 @@
+/* This file is part of the MicroPython project, http://micropython.org/
+ * The MIT License (MIT)
+ * Copyright (c) 2019 Damien P. George
+ */
+#ifndef MICROPY_INCLUDED_STM32F4XX_HAL_CONF_H
+#define MICROPY_INCLUDED_STM32F4XX_HAL_CONF_H
+
+#include "boards/stm32f4xx_hal_conf_base.h"
+
+// Oscillator values in Hz
+#define HSE_VALUE (12000000)
+#define LSE_VALUE (32768)
+#define EXTERNAL_CLOCK_VALUE (12288000)
+
+// Oscillator timeouts in ms
+#define HSE_STARTUP_TIMEOUT (100)
+#define LSE_STARTUP_TIMEOUT (5000)
+
+#endif // MICROPY_INCLUDED_STM32F4XX_HAL_CONF_H
diff --git a/ports/stm32/boards/STM32F429DISC/mpconfigboard.h b/ports/stm32/boards/STM32F429DISC/mpconfigboard.h
index 95cab08c8..cfd9ef9d0 100644
--- a/ports/stm32/boards/STM32F429DISC/mpconfigboard.h
+++ b/ports/stm32/boards/STM32F429DISC/mpconfigboard.h
@@ -19,8 +19,12 @@
 // UART config
 #define MICROPY_HW_UART1_TX     (pin_A9)
 #define MICROPY_HW_UART1_RX     (pin_A10)
-#define MICROPY_HW_UART2_TX     (pin_D8)
-#define MICROPY_HW_UART2_RX     (pin_D9)
+#define MICROPY_HW_UART2_TX     (pin_D5)
+#define MICROPY_HW_UART2_RX     (pin_D6)
+#define MICROPY_HW_UART3_TX     (pin_C10)
+#define MICROPY_HW_UART3_RX     (pin_C11)
+#define MICROPY_HW_UART6_TX     (pin_C6)
+#define MICROPY_HW_UART6_RX     (pin_C7)
 
 // I2C buses
 #define MICROPY_HW_I2C3_SCL (pin_A8)
diff --git a/ports/stm32/boards/USBDONGLE_WB55/mpconfigboard.h b/ports/stm32/boards/USBDONGLE_WB55/mpconfigboard.h
index fdb061900..d4b12ae5b 100644
--- a/ports/stm32/boards/USBDONGLE_WB55/mpconfigboard.h
+++ b/ports/stm32/boards/USBDONGLE_WB55/mpconfigboard.h
@@ -43,8 +43,8 @@
 
 // USB config
 #define MICROPY_HW_USB_FS           (1)
-#define USBD_CDC_RX_DATA_SIZE       (512)
-#define USBD_CDC_TX_DATA_SIZE       (512)
+#define MICROPY_HW_USB_CDC_RX_DATA_SIZE (512)
+#define MICROPY_HW_USB_CDC_TX_DATA_SIZE (512)
 
 // Bluetooth config
 #define MICROPY_HW_BLE_UART_ID       (0)
diff --git a/ports/stm32/boards/make-pins.py b/ports/stm32/boards/make-pins.py
index a19532331..d898832f0 100755
--- a/ports/stm32/boards/make-pins.py
+++ b/ports/stm32/boards/make-pins.py
@@ -22,7 +22,7 @@ SUPPORTED_FN = {
 
 CONDITIONAL_VAR = {
     "I2C": "MICROPY_HW_I2C{num}_SCL",
-    "I2S": "MICROPY_HW_ENABLE_I2S{num}",
+    "I2S": "MICROPY_HW_I2S{num}",
     "SPI": "MICROPY_HW_SPI{num}_SCK",
     "UART": "MICROPY_HW_UART{num}_TX",
     "LPUART": "MICROPY_HW_LPUART{num}_TX",
@@ -287,6 +287,7 @@ class Pins(object):
     def __init__(self):
         self.cpu_pins = []  # list of NamedPin objects
         self.board_pins = []  # list of NamedPin objects
+        self.adc_table_size = {}  # maps ADC number X to size of pin_adcX table
 
     def find_pin(self, port_num, pin_num):
         for named_pin in self.cpu_pins:
@@ -353,27 +354,27 @@ class Pins(object):
         self.print_named("board", self.board_pins)
 
     def print_adc(self, adc_num):
-        print("")
-        print("const pin_obj_t * const pin_adc{:d}[] = {{".format(adc_num))
-        for channel in range(17):
-            if channel == 16:
-                print("#if defined(STM32L4)")
-            adc_found = False
-            for named_pin in self.cpu_pins:
-                pin = named_pin.pin()
-                if (
-                    pin.is_board_pin()
-                    and (pin.adc_num & (1 << (adc_num - 1)))
-                    and (pin.adc_channel == channel)
-                ):
-                    print("  &pin_{:s}_obj, // {:d}".format(pin.cpu_pin_name(), channel))
-                    adc_found = True
-                    break
-            if not adc_found:
-                print("  NULL,    // {:d}".format(channel))
-            if channel == 16:
-                print("#endif")
-        print("};")
+        adc_pins = {}
+        for named_pin in self.cpu_pins:
+            pin = named_pin.pin()
+            if (
+                pin.is_board_pin()
+                and not named_pin.is_hidden()
+                and (pin.adc_num & (1 << (adc_num - 1)))
+            ):
+                adc_pins[pin.adc_channel] = pin
+        if adc_pins:
+            table_size = max(adc_pins) + 1
+            self.adc_table_size[adc_num] = table_size
+            print("")
+            print("const pin_obj_t * const pin_adc{:d}[{:d}] = {{".format(adc_num, table_size))
+            for channel in range(table_size):
+                if channel in adc_pins:
+                    obj = "&pin_{:s}_obj".format(adc_pins[channel].cpu_pin_name())
+                else:
+                    obj = "NULL"
+                print("  [{:d}] = {},".format(channel, obj))
+            print("};")
 
     def print_header(self, hdr_filename, obj_decls):
         with open(hdr_filename, "wt") as hdr_file:
@@ -382,9 +383,12 @@ class Pins(object):
                     pin = named_pin.pin()
                     if pin.is_board_pin():
                         pin.print_header(hdr_file)
-                hdr_file.write("extern const pin_obj_t * const pin_adc1[];\n")
-                hdr_file.write("extern const pin_obj_t * const pin_adc2[];\n")
-                hdr_file.write("extern const pin_obj_t * const pin_adc3[];\n")
+                for adc_num, table_size in self.adc_table_size.items():
+                    hdr_file.write(
+                        "extern const pin_obj_t * const pin_adc{:d}[{:d}];\n".format(
+                            adc_num, table_size
+                        )
+                    )
             # provide #define's mapping board to cpu name
             for named_pin in self.board_pins:
                 hdr_file.write(
@@ -569,9 +573,8 @@ def main():
         with open(args.prefix_filename, "r") as prefix_file:
             print(prefix_file.read())
     pins.print()
-    pins.print_adc(1)
-    pins.print_adc(2)
-    pins.print_adc(3)
+    for i in range(1, 4):
+        pins.print_adc(i)
     pins.print_header(args.hdr_filename, args.hdr_obj_decls)
     pins.print_qstr(args.qstr_filename)
     pins.print_af_hdr(args.af_const_filename)
diff --git a/ports/stm32/boards/stm32h7xx_hal_conf_base.h b/ports/stm32/boards/stm32h7xx_hal_conf_base.h
index c07ae93e3..08928ed59 100644
--- a/ports/stm32/boards/stm32h7xx_hal_conf_base.h
+++ b/ports/stm32/boards/stm32h7xx_hal_conf_base.h
@@ -54,6 +54,7 @@
 #include "stm32h7xx_hal_usart.h"
 #include "stm32h7xx_hal_wwdg.h"
 #include "stm32h7xx_ll_adc.h"
+#include "stm32h7xx_ll_lpuart.h"
 #include "stm32h7xx_ll_pwr.h"
 #include "stm32h7xx_ll_rtc.h"
 #include "stm32h7xx_ll_usart.h"
diff --git a/ports/stm32/boards/stm32l0xx_hal_conf_base.h b/ports/stm32/boards/stm32l0xx_hal_conf_base.h
index cc033666a..7b569907e 100644
--- a/ports/stm32/boards/stm32l0xx_hal_conf_base.h
+++ b/ports/stm32/boards/stm32l0xx_hal_conf_base.h
@@ -47,6 +47,7 @@
 #include "stm32l0xx_hal_usart.h"
 #include "stm32l0xx_hal_wwdg.h"
 #include "stm32l0xx_ll_adc.h"
+#include "stm32l0xx_ll_lpuart.h"
 #include "stm32l0xx_ll_rtc.h"
 #include "stm32l0xx_ll_usart.h"
 
diff --git a/ports/stm32/boards/stm32l4xx_hal_conf_base.h b/ports/stm32/boards/stm32l4xx_hal_conf_base.h
index 8d77a80a7..4f3a78d50 100644
--- a/ports/stm32/boards/stm32l4xx_hal_conf_base.h
+++ b/ports/stm32/boards/stm32l4xx_hal_conf_base.h
@@ -51,6 +51,7 @@
 #include "stm32l4xx_hal_usart.h"
 #include "stm32l4xx_hal_wwdg.h"
 #include "stm32l4xx_ll_adc.h"
+#include "stm32l4xx_ll_lpuart.h"
 #include "stm32l4xx_ll_rtc.h"
 #include "stm32l4xx_ll_usart.h"
 
diff --git a/ports/stm32/boards/stm32wbxx_hal_conf_base.h b/ports/stm32/boards/stm32wbxx_hal_conf_base.h
index 72af0262a..b03ad2686 100644
--- a/ports/stm32/boards/stm32wbxx_hal_conf_base.h
+++ b/ports/stm32/boards/stm32wbxx_hal_conf_base.h
@@ -42,6 +42,7 @@
 #include "stm32wbxx_hal_uart.h"
 #include "stm32wbxx_hal_usart.h"
 #include "stm32wbxx_ll_adc.h"
+#include "stm32wbxx_ll_lpuart.h"
 #include "stm32wbxx_ll_rtc.h"
 #include "stm32wbxx_ll_usart.h"
 
diff --git a/ports/stm32/dma.c b/ports/stm32/dma.c
index de3088691..ba09dc170 100644
--- a/ports/stm32/dma.c
+++ b/ports/stm32/dma.c
@@ -103,6 +103,31 @@ static const DMA_InitTypeDef dma_init_struct_spi_i2c = {
     #endif
 };
 
+#if MICROPY_HW_ENABLE_I2S
+// Default parameters to dma_init() for i2s; Channel and Direction
+// vary depending on the peripheral instance so they get passed separately
+static const DMA_InitTypeDef dma_init_struct_i2s = {
+    #if defined(STM32F4) || defined(STM32F7)
+    .Channel = 0,
+    #elif defined(STM32H7) || defined(STM32L0) || defined(STM32L4)
+    .Request = 0,
+    #endif
+    .Direction = DMA_MEMORY_TO_PERIPH,
+    .PeriphInc = DMA_PINC_DISABLE,
+    .MemInc = DMA_MINC_ENABLE,
+    .PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD,
+    .MemDataAlignment = DMA_MDATAALIGN_HALFWORD,
+    .Mode = DMA_CIRCULAR,
+    .Priority = DMA_PRIORITY_LOW,
+    #if defined(STM32F4) || defined(STM32F7) || defined(STM32H7)
+    .FIFOMode = DMA_FIFOMODE_DISABLE,
+    .FIFOThreshold = DMA_FIFO_THRESHOLD_FULL,
+    .MemBurst = DMA_MBURST_SINGLE,
+    .PeriphBurst = DMA_PBURST_SINGLE
+    #endif
+};
+#endif
+
 #if ENABLE_SDIO && !defined(STM32H7)
 // Parameters to dma_init() for SDIO tx and rx.
 static const DMA_InitTypeDef dma_init_struct_sdio = {
@@ -242,6 +267,10 @@ const dma_descr_t dma_I2C_3_RX = { DMA1_Stream2, DMA_CHANNEL_3, dma_id_2,   &dma
 const dma_descr_t dma_I2C_2_RX = { DMA1_Stream2, DMA_CHANNEL_7, dma_id_2,   &dma_init_struct_spi_i2c };
 const dma_descr_t dma_SPI_2_RX = { DMA1_Stream3, DMA_CHANNEL_0, dma_id_3,   &dma_init_struct_spi_i2c };
 const dma_descr_t dma_SPI_2_TX = { DMA1_Stream4, DMA_CHANNEL_0, dma_id_4,   &dma_init_struct_spi_i2c };
+#if MICROPY_HW_ENABLE_I2S
+const dma_descr_t dma_I2S_2_RX = { DMA1_Stream3, DMA_CHANNEL_0, dma_id_3,   &dma_init_struct_i2s };
+const dma_descr_t dma_I2S_2_TX = { DMA1_Stream4, DMA_CHANNEL_0, dma_id_4,   &dma_init_struct_i2s };
+#endif
 const dma_descr_t dma_I2C_3_TX = { DMA1_Stream4, DMA_CHANNEL_3, dma_id_4,   &dma_init_struct_spi_i2c };
 #if defined(STM32F7)
 const dma_descr_t dma_I2C_4_TX = { DMA1_Stream5, DMA_CHANNEL_2, dma_id_5,   &dma_init_struct_spi_i2c };
@@ -266,6 +295,9 @@ const dma_descr_t dma_SDMMC_2 = { DMA2_Stream0, DMA_CHANNEL_11, dma_id_8,  &dma_
 const dma_descr_t dma_DCMI_0 = { DMA2_Stream1, DMA_CHANNEL_1, dma_id_9,  &dma_init_struct_dcmi };
 #endif
 const dma_descr_t dma_SPI_1_RX = { DMA2_Stream2, DMA_CHANNEL_3, dma_id_10,  &dma_init_struct_spi_i2c };
+#if MICROPY_HW_ENABLE_I2S
+const dma_descr_t dma_I2S_1_RX = { DMA2_Stream2, DMA_CHANNEL_3, dma_id_10,  &dma_init_struct_i2s };
+#endif
 const dma_descr_t dma_SPI_5_RX = { DMA2_Stream3, DMA_CHANNEL_2, dma_id_11,  &dma_init_struct_spi_i2c };
 #if ENABLE_SDIO
 const dma_descr_t dma_SDIO_0 = { DMA2_Stream3, DMA_CHANNEL_4, dma_id_11,  &dma_init_struct_sdio };
@@ -275,6 +307,9 @@ const dma_descr_t dma_SPI_5_TX = { DMA2_Stream4, DMA_CHANNEL_2, dma_id_12,  &dma
 const dma_descr_t dma_SPI_4_TX = { DMA2_Stream4, DMA_CHANNEL_5, dma_id_12,  &dma_init_struct_spi_i2c };
 const dma_descr_t dma_SPI_6_TX = { DMA2_Stream5, DMA_CHANNEL_1, dma_id_13,  &dma_init_struct_spi_i2c };
 const dma_descr_t dma_SPI_1_TX = { DMA2_Stream5, DMA_CHANNEL_3, dma_id_13,  &dma_init_struct_spi_i2c };
+#if MICROPY_HW_ENABLE_I2S
+const dma_descr_t dma_I2S_1_TX = { DMA2_Stream5, DMA_CHANNEL_3, dma_id_13,  &dma_init_struct_i2s };
+#endif
 // #if defined(STM32F7) && defined(SDMMC2) && ENABLE_SDIO
 // const dma_descr_t dma_SDMMC_2 = { DMA2_Stream5, DMA_CHANNEL_11, dma_id_13,  &dma_init_struct_sdio };
 // #endif
diff --git a/ports/stm32/dma.h b/ports/stm32/dma.h
index 5a17276a4..8bd101a61 100644
--- a/ports/stm32/dma.h
+++ b/ports/stm32/dma.h
@@ -57,6 +57,10 @@ extern const dma_descr_t dma_SDMMC_2;
 extern const dma_descr_t dma_SPI_6_RX;
 extern const dma_descr_t dma_SDIO_0;
 extern const dma_descr_t dma_DCMI_0;
+extern const dma_descr_t dma_I2S_1_RX;
+extern const dma_descr_t dma_I2S_1_TX;
+extern const dma_descr_t dma_I2S_2_RX;
+extern const dma_descr_t dma_I2S_2_TX;
 
 #elif defined(STM32L0)
 
diff --git a/ports/stm32/eth.c b/ports/stm32/eth.c
index 79165e119..f174b6af0 100644
--- a/ports/stm32/eth.c
+++ b/ports/stm32/eth.c
@@ -27,7 +27,7 @@
 #include <string.h>
 #include "py/mphal.h"
 #include "py/mperrno.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "pin_static_af.h"
 #include "modnetwork.h"
 #include "mpu.h"
diff --git a/ports/stm32/flashbdev.c b/ports/stm32/flashbdev.c
index 4153a713c..6ed891300 100644
--- a/ports/stm32/flashbdev.c
+++ b/ports/stm32/flashbdev.c
@@ -157,6 +157,7 @@ int32_t flash_bdev_ioctl(uint32_t op, uint32_t arg) {
             return 0;
 
         case BDEV_IOCTL_NUM_BLOCKS:
+            // Units are FLASH_BLOCK_SIZE
             return FLASH_MEM_SEG1_NUM_BLOCKS + FLASH_MEM_SEG2_NUM_BLOCKS;
 
         case BDEV_IOCTL_IRQ_HANDLER:
diff --git a/ports/stm32/gccollect.c b/ports/stm32/gccollect.c
index 8b47b121e..bd697a2af 100644
--- a/ports/stm32/gccollect.c
+++ b/ports/stm32/gccollect.c
@@ -30,7 +30,7 @@
 #include "py/mpstate.h"
 #include "py/gc.h"
 #include "py/mpthread.h"
-#include "lib/utils/gchelper.h"
+#include "shared/runtime/gchelper.h"
 #include "gccollect.h"
 #include "softtimer.h"
 #include "systick.h"
diff --git a/ports/stm32/machine_bitstream.c b/ports/stm32/machine_bitstream.c
new file mode 100644
index 000000000..6cc367937
--- /dev/null
+++ b/ports/stm32/machine_bitstream.c
@@ -0,0 +1,204 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Jim Mussared
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "extmod/machine_bitstream.h"
+
+#if MICROPY_PY_MACHINE_BITSTREAM
+
+#if __CORTEX_M == 0
+
+// No cycle counter on M0, do manual cycle counting instead.
+
+// STM32F091 @ 48MHz
+#define NS_CYCLES_PER_ITER_HIGH (6)
+#define NS_CYCLES_PER_ITER_LOW (6)
+#define NS_OVERHEAD_CYCLES_HIGH (12)
+#define NS_OVERHEAD_CYCLES_LOW (18)
+
+uint32_t mp_hal_delay_ns_calc(uint32_t ns, bool high) {
+    uint32_t ncycles = SystemCoreClock / 1000000 * ns / 1000;
+    uint32_t overhead = MIN(ncycles, high ? NS_OVERHEAD_CYCLES_HIGH : NS_OVERHEAD_CYCLES_LOW);
+    return MAX(1, MP_ROUND_DIVIDE(ncycles - overhead, high ? NS_CYCLES_PER_ITER_HIGH : NS_CYCLES_PER_ITER_LOW));
+}
+
+void machine_bitstream_high_low(mp_hal_pin_obj_t pin, uint32_t *timing_ns, const uint8_t *buf, size_t len) {
+    const uint32_t high_mask = pin->pin_mask;
+    const uint32_t low_mask = pin->pin_mask << 16;
+    volatile uint32_t *bsrr = &pin->gpio->BSRR;
+
+    // Convert ns to loop iterations [high_time_0, low_time_0, high_time_1, low_time_1].
+    for (size_t i = 0; i < 4; ++i) {
+        timing_ns[i] = mp_hal_delay_ns_calc(timing_ns[i], i % 2 == 0);
+    }
+
+    mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+
+    // Measured timing for F091 at 48MHz (cycle=20.83ns)
+    // timing_ns = (1,1,1,1)
+    //   high: 370
+    //   low:  500
+    //   low8: 660
+    // timing_ns = (2,2,2,2)
+    //   high: 490
+    //   low:  620
+    //   low8: 805
+
+    // --> high is 12 + n*6 cycles
+    //     low is 18 + n*6 cycles
+
+    // NeoPixel timing (400, 850, 800, 450) (+/-150ns) gives timing_ns=(1, 4, 4, 1) which in cycles is
+    // (12 + 6, 18 + 24, 12 + 24, 18 + 6) = (18, 42, 36, 24)
+    // --> (375, 875, 750, 500) nanoseconds.
+    // Measured output on logic analyser is (370, 870, 750, 490) (+/-10ns at 100MHz)
+
+    // Note: final low of LSB is longer by 8 cycles (160ns) (due to start of outer loop and fetching next byte).
+    // This is slightly outside spec, but doesn't seem to cause a problem.
+
+    __asm volatile (
+        // Force consistent register assignment.
+        // r6 = len
+        "ldr r6, %0\n"
+        // r4 = buf
+        "ldr r4, %1\n"
+        // r5 = timing_ms
+        "ldr r5, %2\n"
+
+        // Must align for consistent timing.
+        ".align 4\n"
+
+        // Don't increment/decrement before first iteration.
+        "b .outer2\n"
+        ".outer:\n"
+        // ++buf, --len
+        "  add r4, #1\n"
+        "  sub r6, #1\n"
+
+        // len iterations
+        ".outer2:\n"
+        "  cmp r6, #0\n"
+        "  beq .done\n"
+
+        // r0 = *buf
+        "  ldrb r0, [r4, #0]\n"
+
+        // 8 bits in byte
+        "  mov r7, #8\n"
+        "  .inner:\n"
+        //   *bsrr = high_mask
+        "    ldr r1, %3\n"
+        "    ldr r2, %4\n"
+        "    str r2, [r1, #0]\n"
+
+        //   r3 = (r0 >> 4) & 8    (r0 is 8 if high bit is 1 else 0)
+        "    mov r8, r6\n"
+        "    lsr r3, r0, #4\n"
+        "    mov r6, #8\n"
+        "    and r3, r6\n"
+        "    mov r6, r8\n"
+
+        //   r2 = timing_ns[r2]
+        "    ldr r2, [r5, r3]\n"
+        "    .loop1:\n sub r2, #1\n bne .loop1\n"
+
+        //   *bsrr = low_mask
+        "    ldr r2, %5\n"
+        "    str r2, [r1, #0]\n"
+
+        //   r2 = timing_ns[r3 + 4]
+        "    add r3, #4\n"
+        "    ldr r2, [r5, r3]\n"
+        "    .loop2:\n sub r2, #1\n bne .loop2\n"
+
+        //   b >>= 1
+        "    lsl r0, r0, #1\n"
+
+        "    sub r7, #1\n"
+        //   end of inner loop
+        "    beq .outer\n"
+        //   continue inner loop
+        "    b .inner\n"
+
+        ".done:\n"
+        :
+        : "m" (len), "m" (buf), "m" (timing_ns), "m" (bsrr), "m" (high_mask), "m" (low_mask)
+        : "r0", "r1", "r2", "r3", "r7", "r8"
+        );
+
+    MICROPY_END_ATOMIC_SECTION(atomic_state);
+}
+
+#else // > CORTEX_M0
+
+// Use cycle counter for timing.
+
+// Measured on PYBV11 at 168MHz & 128MHz and PYBD_SF6 at 128MHz & 144MHz.
+#define NS_CYCLES_OVERHEAD (6)
+
+void machine_bitstream_high_low(mp_hal_pin_obj_t pin, uint32_t *timing_ns, const uint8_t *buf, size_t len) {
+    const uint32_t high_mask = pin->pin_mask;
+    const uint32_t low_mask = pin->pin_mask << 16;
+    volatile uint32_t *bsrr = &pin->gpio->BSRR;
+
+    // Convert ns to cycles [high_time_0, low_time_0, high_time_1, low_time_1].
+    for (size_t i = 0; i < 4; ++i) {
+        timing_ns[i] = SystemCoreClock / 1000000 * timing_ns[i] / 1000;
+        if (timing_ns[i] > NS_CYCLES_OVERHEAD) {
+            timing_ns[i] -= NS_CYCLES_OVERHEAD;
+        }
+        if (i % 2 == 1) {
+            timing_ns[i] += timing_ns[i - 1];
+        }
+    }
+
+    mp_hal_ticks_cpu_enable();
+
+    mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+
+    for (size_t i = 0; i < len; ++i) {
+        uint8_t b = buf[i];
+        for (size_t j = 0; j < 8; ++j) {
+            DWT->CYCCNT = 0;
+            *bsrr = high_mask;
+            uint32_t *t = &timing_ns[b >> 6 & 2];
+            while (DWT->CYCCNT < t[0]) {
+                ;
+            }
+            *bsrr = low_mask;
+            b <<= 1;
+            while (DWT->CYCCNT < t[1]) {
+                ;
+            }
+        }
+    }
+
+    MICROPY_END_ATOMIC_SECTION(atomic_state);
+}
+
+#endif // > CORTEX_M0
+
+#endif // MICROPY_PY_MACHINE_BITSTREAM
diff --git a/ports/stm32/machine_i2s.c b/ports/stm32/machine_i2s.c
new file mode 100644
index 000000000..32167cf4e
--- /dev/null
+++ b/ports/stm32/machine_i2s.c
@@ -0,0 +1,1125 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 Bryan Morrissey
+ * Copyright (c) 2021 Mike Teachman
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include "py/obj.h"
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "py/misc.h"
+#include "py/stream.h"
+#include "py/objstr.h"
+#include "modmachine.h"
+#include "pin.h"
+#include "dma.h"
+
+#if MICROPY_HW_ENABLE_I2S
+// The I2S module has 3 modes of operation:
+//
+// Mode1:  Blocking
+// - readinto() and write() methods block until the supplied buffer is filled (read) or emptied (write)
+// - this is the default mode of operation
+//
+// Mode2:  Non-Blocking
+// - readinto() and write() methods return immediately
+// - buffer filling and emptying happens asynchronously to the main MicroPython task
+// - a callback function is called when the supplied buffer has been filled (read) or emptied (write)
+// - non-blocking mode is enabled when a callback is set with the irq() method
+// - the DMA callbacks (1/2 complete and complete) are used to implement the asynchronous background operations
+//
+// Mode3: Uasyncio
+// - implements the stream protocol
+// - uasyncio mode is enabled when the ioctl() function is called
+// - the state of the internal ring buffer is used to detect that I2S samples can be read or written
+//
+// The samples contained in the app buffer supplied for the readinto() and write() methods have the following convention:
+//   Mono:  little endian format
+//   Stereo:  little endian format, left channel first
+//
+// I2S terms:
+//   "frame":  consists of two audio samples (Left audio sample + Right audio sample)
+//
+// Misc:
+// - for Mono configuration:
+//   - readinto method: samples are gathered from the L channel only
+//   - write method: every sample is output to both the L and R channels
+// - for readinto method the I2S hardware is read using 8-byte frames
+//   (this is standard for almost all I2S hardware, such as MEMS microphones)
+// - all 3 Modes of operation are implemented using the HAL I2S Generic Driver
+// - all sample data transfers use DMA
+// - the DMA controller is configured in Circular mode to fulfil continuous and gapless sample flows
+// - the DMA ping-pong buffer needs to be aligned to a cache line size of 32 bytes.  32 byte
+//   alignment is needed to use the routines that clean and invalidate D-Cache which work on a
+//   32 byte address boundary.  Not all STM32 devices have a D-Cache.  Buffer alignment
+//   will still happen on these devices to keep this code simple.
+
+#define MAX_I2S_STM32 (2)
+
+// DMA ping-pong buffer size was empirically determined.  It is a tradeoff between:
+// 1. memory use (smaller buffer size desirable to reduce memory footprint)
+// 2. interrupt frequency (larger buffer size desirable to reduce interrupt frequency)
+// The sizeof 1/2 of the DMA buffer must be evenly divisible by the cache line size of 32 bytes.
+#define SIZEOF_DMA_BUFFER_IN_BYTES (256)
+#define SIZEOF_HALF_DMA_BUFFER_IN_BYTES (SIZEOF_DMA_BUFFER_IN_BYTES / 2)
+
+// For non-blocking mode, to avoid underflow/overflow, sample data is written/read to/from the ring buffer at a rate faster
+// than the DMA transfer rate
+#define NON_BLOCKING_RATE_MULTIPLIER (4)
+#define SIZEOF_NON_BLOCKING_COPY_IN_BYTES (SIZEOF_HALF_DMA_BUFFER_IN_BYTES * NON_BLOCKING_RATE_MULTIPLIER)
+
+#define NUM_I2S_USER_FORMATS (4)
+#define I2S_RX_FRAME_SIZE_IN_BYTES (8)
+
+typedef enum {
+    MONO,
+    STEREO
+} format_t;
+
+typedef enum {
+    BLOCKING,
+    NON_BLOCKING,
+    UASYNCIO
+} io_mode_t;
+
+typedef enum {
+    TOP_HALF,
+    BOTTOM_HALF
+} ping_pong_t;
+
+typedef struct _ring_buf_t {
+    uint8_t *buffer;
+    size_t head;
+    size_t tail;
+    size_t size;
+} ring_buf_t;
+
+typedef struct _non_blocking_descriptor_t {
+    mp_buffer_info_t appbuf;
+    uint32_t index;
+    bool copy_in_progress;
+} non_blocking_descriptor_t;
+
+typedef struct _machine_i2s_obj_t {
+    mp_obj_base_t base;
+    uint8_t i2s_id;
+    mp_hal_pin_obj_t sck;
+    mp_hal_pin_obj_t ws;
+    mp_hal_pin_obj_t sd;
+    uint16_t mode;
+    int8_t bits;
+    format_t format;
+    int32_t rate;
+    int32_t ibuf;
+    mp_obj_t callback_for_non_blocking;
+    uint8_t dma_buffer[SIZEOF_DMA_BUFFER_IN_BYTES + 0x1f]; // 0x1f related to D-Cache alignment
+    uint8_t *dma_buffer_dcache_aligned;
+    ring_buf_t ring_buffer;
+    uint8_t *ring_buffer_storage;
+    non_blocking_descriptor_t non_blocking_descriptor;
+    io_mode_t io_mode;
+    I2S_HandleTypeDef hi2s;
+    DMA_HandleTypeDef hdma_tx;
+    DMA_HandleTypeDef hdma_rx;
+    const dma_descr_t *dma_descr_tx;
+    const dma_descr_t *dma_descr_rx;
+} machine_i2s_obj_t;
+
+STATIC mp_obj_t machine_i2s_deinit(mp_obj_t self_in);
+
+// The frame map is used with the readinto() method to transform the audio sample data coming
+// from DMA memory (32-bit stereo) to the format specified
+// in the I2S constructor.  e.g.  16-bit mono
+STATIC const int8_t i2s_frame_map[NUM_I2S_USER_FORMATS][I2S_RX_FRAME_SIZE_IN_BYTES] = {
+    { 0,  1, -1, -1, -1, -1, -1, -1 },  // Mono, 16-bits
+    { 2,  3,  0,  1, -1, -1, -1, -1 },  // Mono, 32-bits
+    { 0,  1,  4,  5, -1, -1, -1, -1 },  // Stereo, 16-bits
+    { 2,  3,  0,  1,  6,  7,  4,  5 },  // Stereo, 32-bits
+};
+
+STATIC machine_i2s_obj_t *machine_i2s_obj[MAX_I2S_STM32];
+
+void machine_i2s_init0() {
+    for (uint8_t i = 0; i < MAX_I2S_STM32; i++) {
+        machine_i2s_obj[i] = NULL;
+    }
+}
+
+// Ring Buffer
+// Thread safe when used with these constraints:
+// - Single Producer, Single Consumer
+// - Sequential atomic operations
+// One byte of capacity is used to detect buffer empty/full
+
+STATIC void ringbuf_init(ring_buf_t *rbuf, uint8_t *buffer, size_t size) {
+    rbuf->buffer = buffer;
+    rbuf->size = size;
+    rbuf->head = 0;
+    rbuf->tail = 0;
+}
+
+STATIC bool ringbuf_push(ring_buf_t *rbuf, uint8_t data) {
+    size_t next_tail = (rbuf->tail + 1) % rbuf->size;
+
+    if (next_tail != rbuf->head) {
+        rbuf->buffer[rbuf->tail] = data;
+        rbuf->tail = next_tail;
+        return true;
+    }
+
+    // full
+    return false;
+}
+
+STATIC bool ringbuf_pop(ring_buf_t *rbuf, uint8_t *data) {
+    if (rbuf->head == rbuf->tail) {
+        // empty
+        return false;
+    }
+
+    *data = rbuf->buffer[rbuf->head];
+    rbuf->head = (rbuf->head + 1) % rbuf->size;
+    return true;
+}
+
+STATIC bool ringbuf_is_empty(ring_buf_t *rbuf) {
+    return rbuf->head == rbuf->tail;
+}
+
+STATIC bool ringbuf_is_full(ring_buf_t *rbuf) {
+    return ((rbuf->tail + 1) % rbuf->size) == rbuf->head;
+}
+
+STATIC size_t ringbuf_available_data(ring_buf_t *rbuf) {
+    return (rbuf->tail - rbuf->head + rbuf->size) % rbuf->size;
+}
+
+STATIC size_t ringbuf_available_space(ring_buf_t *rbuf) {
+    return rbuf->size - ringbuf_available_data(rbuf) - 1;
+}
+
+//  For 32-bit audio samples, the STM32 HAL API expects each 32-bit sample to be encoded
+//  in an unusual byte ordering:  Byte_2, Byte_3, Byte_0, Byte_1
+//      where:  Byte_0 is the least significant byte of the 32-bit sample
+//
+//  The following function takes a buffer containing 32-bits sample values formatted as little endian
+//  and performs an in-place modification into the STM32 HAL API convention
+//
+//  Example:
+//
+//   wav_samples[] = [L_0-7,   L_8-15,  L_16-23, L_24-31, R_0-7,   R_8-15,  R_16-23, R_24-31] =  [Left channel, Right channel]
+//   stm_api[] =     [L_16-23, L_24-31, L_0-7,   L_8-15,  R_16-23, R_24-31, R_0-7,   R_8-15] = [Left channel, Right channel]
+//
+//   where:
+//      L_0-7 is the least significant byte of the 32 bit sample in the Left channel
+//      L_24-31 is the most significant byte of the 32 bit sample in the Left channel
+//
+//   wav_samples[] =  [0x99, 0xBB, 0x11, 0x22, 0x44, 0x55, 0xAB, 0x77] = [Left channel, Right channel]
+//   stm_api[] =      [0x11, 0x22, 0x99, 0xBB, 0xAB, 0x77, 0x44, 0x55] = [Left channel, Right channel]
+//
+//   where:
+//      LEFT Channel =  0x99, 0xBB, 0x11, 0x22
+//      RIGHT Channel = 0x44, 0x55, 0xAB, 0x77
+STATIC void reformat_32_bit_samples(int32_t *sample, uint32_t num_samples) {
+    int16_t sample_ms;
+    int16_t sample_ls;
+    for (uint32_t i = 0; i < num_samples; i++) {
+        sample_ls = sample[i] & 0xFFFF;
+        sample_ms = sample[i] >> 16;
+        sample[i] = (sample_ls << 16) + sample_ms;
+    }
+}
+
+STATIC int8_t get_frame_mapping_index(int8_t bits, format_t format) {
+    if (format == MONO) {
+        if (bits == 16) {
+            return 0;
+        } else { // 32 bits
+            return 1;
+        }
+    } else { // STEREO
+        if (bits == 16) {
+            return 2;
+        } else { // 32 bits
+            return 3;
+        }
+    }
+}
+
+STATIC int8_t get_dma_bits(uint16_t mode, int8_t bits) {
+    if (mode == I2S_MODE_MASTER_TX) {
+        if (bits == 16) {
+            return I2S_DATAFORMAT_16B;
+        } else {
+            return I2S_DATAFORMAT_32B;
+        }
+        return bits;
+    } else { // Master Rx
+        // always read 32 bit words for I2S e.g.  I2S MEMS microphones
+        return I2S_DATAFORMAT_32B;
+    }
+}
+
+STATIC uint32_t fill_appbuf_from_ringbuf(machine_i2s_obj_t *self, mp_buffer_info_t *appbuf) {
+
+    // copy audio samples from the ring buffer to the app buffer
+    // loop, copying samples until the app buffer is filled
+    // For uasyncio mode, the loop will make an early exit if the ring buffer becomes empty
+    // Example:
+    //   a MicroPython I2S object is configured for 16-bit mono (2 bytes per audio sample).
+    //   For every frame coming from the ring buffer (8 bytes), 2 bytes are "cherry picked" and
+    //   copied to the supplied app buffer.
+    //   Thus, for every 1 byte copied to the app buffer, 4 bytes are read from the ring buffer.
+    //   If a 8kB app buffer is supplied, 32kB of audio samples is read from the ring buffer.
+
+    uint32_t num_bytes_copied_to_appbuf = 0;
+    uint8_t *app_p = (uint8_t *)appbuf->buf;
+    uint8_t appbuf_sample_size_in_bytes = (self->bits == 16? 2 : 4) * (self->format == STEREO ? 2: 1);
+    uint32_t num_bytes_needed_from_ringbuf = appbuf->len * (I2S_RX_FRAME_SIZE_IN_BYTES / appbuf_sample_size_in_bytes);
+    uint8_t discard_byte;
+    while (num_bytes_needed_from_ringbuf) {
+
+        uint8_t f_index = get_frame_mapping_index(self->bits, self->format);
+
+        for (uint8_t i = 0; i < I2S_RX_FRAME_SIZE_IN_BYTES; i++) {
+            int8_t r_to_a_mapping = i2s_frame_map[f_index][i];
+            if (r_to_a_mapping != -1) {
+                if (self->io_mode == BLOCKING) {
+                    // poll the ringbuf until a sample becomes available,  copy into appbuf using the mapping transform
+                    while (ringbuf_pop(&self->ring_buffer, app_p + r_to_a_mapping) == false) {
+                        ;
+                    }
+                    num_bytes_copied_to_appbuf++;
+                } else if (self->io_mode == UASYNCIO) {
+                    if (ringbuf_pop(&self->ring_buffer, app_p + r_to_a_mapping) == false) {
+                        // ring buffer is empty, exit
+                        goto exit;
+                    } else {
+                        num_bytes_copied_to_appbuf++;
+                    }
+                } else {
+                    return 0;  // should never get here (non-blocking mode does not use this function)
+                }
+            } else { // r_a_mapping == -1
+                // discard unused byte from ring buffer
+                if (self->io_mode == BLOCKING) {
+                    // poll the ringbuf until a sample becomes available
+                    while (ringbuf_pop(&self->ring_buffer, &discard_byte) == false) {
+                        ;
+                    }
+                } else if (self->io_mode == UASYNCIO) {
+                    if (ringbuf_pop(&self->ring_buffer, &discard_byte) == false) {
+                        // ring buffer is empty, exit
+                        goto exit;
+                    }
+                } else {
+                    return 0;  // should never get here (non-blocking mode does not use this function)
+                }
+            }
+            num_bytes_needed_from_ringbuf--;
+        }
+        app_p += appbuf_sample_size_in_bytes;
+    }
+exit:
+    return num_bytes_copied_to_appbuf;
+}
+
+// function is used in IRQ context
+STATIC void fill_appbuf_from_ringbuf_non_blocking(machine_i2s_obj_t *self) {
+
+    // attempt to copy a block of audio samples from the ring buffer to the supplied app buffer.
+    // audio samples will be formatted as part of the copy operation
+
+    uint32_t num_bytes_copied_to_appbuf = 0;
+    uint8_t *app_p = &(((uint8_t *)self->non_blocking_descriptor.appbuf.buf)[self->non_blocking_descriptor.index]);
+
+    uint8_t appbuf_sample_size_in_bytes = (self->bits == 16? 2 : 4) * (self->format == STEREO ? 2: 1);
+    uint32_t num_bytes_remaining_to_copy_to_appbuf = self->non_blocking_descriptor.appbuf.len - self->non_blocking_descriptor.index;
+    uint32_t num_bytes_remaining_to_copy_from_ring_buffer = num_bytes_remaining_to_copy_to_appbuf *
+        (I2S_RX_FRAME_SIZE_IN_BYTES / appbuf_sample_size_in_bytes);
+    uint32_t num_bytes_needed_from_ringbuf = MIN(SIZEOF_NON_BLOCKING_COPY_IN_BYTES, num_bytes_remaining_to_copy_from_ring_buffer);
+    uint8_t discard_byte;
+    if (ringbuf_available_data(&self->ring_buffer) >= num_bytes_needed_from_ringbuf) {
+        while (num_bytes_needed_from_ringbuf) {
+
+            uint8_t f_index = get_frame_mapping_index(self->bits, self->format);
+
+            for (uint8_t i = 0; i < I2S_RX_FRAME_SIZE_IN_BYTES; i++) {
+                int8_t r_to_a_mapping = i2s_frame_map[f_index][i];
+                if (r_to_a_mapping != -1) {
+                    ringbuf_pop(&self->ring_buffer, app_p + r_to_a_mapping);
+                    num_bytes_copied_to_appbuf++;
+                } else { // r_a_mapping == -1
+                    // discard unused byte from ring buffer
+                    ringbuf_pop(&self->ring_buffer, &discard_byte);
+                }
+                num_bytes_needed_from_ringbuf--;
+            }
+            app_p += appbuf_sample_size_in_bytes;
+        }
+        self->non_blocking_descriptor.index += num_bytes_copied_to_appbuf;
+
+        if (self->non_blocking_descriptor.index >= self->non_blocking_descriptor.appbuf.len) {
+            self->non_blocking_descriptor.copy_in_progress = false;
+            mp_sched_schedule(self->callback_for_non_blocking, MP_OBJ_FROM_PTR(self));
+        }
+    }
+}
+
+STATIC uint32_t copy_appbuf_to_ringbuf(machine_i2s_obj_t *self, mp_buffer_info_t *appbuf) {
+
+    // copy audio samples from the app buffer to the ring buffer
+    // loop, reading samples until the app buffer is emptied
+    // for uasyncio mode, the loop will make an early exit if the ring buffer becomes full
+
+    uint32_t a_index = 0;
+
+    while (a_index < appbuf->len) {
+        if (self->io_mode == BLOCKING) {
+            // copy a byte to the ringbuf when space becomes available
+            while (ringbuf_push(&self->ring_buffer, ((uint8_t *)appbuf->buf)[a_index]) == false) {
+                ;
+            }
+            a_index++;
+        } else if (self->io_mode == UASYNCIO) {
+            if (ringbuf_push(&self->ring_buffer, ((uint8_t *)appbuf->buf)[a_index]) == false) {
+                // ring buffer is full, exit
+                break;
+            } else {
+                a_index++;
+            }
+        } else {
+            return 0;  // should never get here (non-blocking mode does not use this function)
+        }
+    }
+
+    return a_index;
+}
+
+// function is used in IRQ context
+STATIC void copy_appbuf_to_ringbuf_non_blocking(machine_i2s_obj_t *self) {
+
+    // copy audio samples from app buffer into ring buffer
+    uint32_t num_bytes_remaining_to_copy = self->non_blocking_descriptor.appbuf.len - self->non_blocking_descriptor.index;
+    uint32_t num_bytes_to_copy = MIN(SIZEOF_NON_BLOCKING_COPY_IN_BYTES, num_bytes_remaining_to_copy);
+
+    if (ringbuf_available_space(&self->ring_buffer) >= num_bytes_to_copy) {
+        for (uint32_t i = 0; i < num_bytes_to_copy; i++) {
+            ringbuf_push(&self->ring_buffer,
+                ((uint8_t *)self->non_blocking_descriptor.appbuf.buf)[self->non_blocking_descriptor.index + i]);
+        }
+
+        self->non_blocking_descriptor.index += num_bytes_to_copy;
+        if (self->non_blocking_descriptor.index >= self->non_blocking_descriptor.appbuf.len) {
+            self->non_blocking_descriptor.copy_in_progress = false;
+            mp_sched_schedule(self->callback_for_non_blocking, MP_OBJ_FROM_PTR(self));
+        }
+    }
+}
+
+// function is used in IRQ context
+STATIC void empty_dma(machine_i2s_obj_t *self, ping_pong_t dma_ping_pong) {
+    uint16_t dma_buffer_offset = 0;
+
+    if (dma_ping_pong == TOP_HALF) {
+        dma_buffer_offset = 0;
+    } else { // BOTTOM_HALF
+        dma_buffer_offset = SIZEOF_HALF_DMA_BUFFER_IN_BYTES;
+    }
+
+    uint8_t *dma_buffer_p = &self->dma_buffer_dcache_aligned[dma_buffer_offset];
+
+    // flush and invalidate cache so the CPU reads data placed into RAM by DMA
+    MP_HAL_CLEANINVALIDATE_DCACHE(dma_buffer_p, SIZEOF_HALF_DMA_BUFFER_IN_BYTES);
+
+    // when space exists, copy samples into ring buffer
+    if (ringbuf_available_space(&self->ring_buffer) >= SIZEOF_HALF_DMA_BUFFER_IN_BYTES) {
+        for (uint32_t i = 0; i < SIZEOF_HALF_DMA_BUFFER_IN_BYTES; i++) {
+            ringbuf_push(&self->ring_buffer, dma_buffer_p[i]);
+        }
+    }
+}
+
+// function is used in IRQ context
+STATIC void feed_dma(machine_i2s_obj_t *self, ping_pong_t dma_ping_pong) {
+    uint16_t dma_buffer_offset = 0;
+
+    if (dma_ping_pong == TOP_HALF) {
+        dma_buffer_offset = 0;
+    } else { // BOTTOM_HALF
+        dma_buffer_offset = SIZEOF_HALF_DMA_BUFFER_IN_BYTES;
+    }
+
+    uint8_t *dma_buffer_p = &self->dma_buffer_dcache_aligned[dma_buffer_offset];
+
+    // when data exists, copy samples from ring buffer
+    if (ringbuf_available_data(&self->ring_buffer) >= SIZEOF_HALF_DMA_BUFFER_IN_BYTES) {
+
+        // copy a block of samples from the ring buffer to the dma buffer.
+        // STM32 HAL API has a stereo I2S implementation, but not mono
+        // mono format is implemented by duplicating each sample into both L and R channels.
+        if ((self->format == MONO) && (self->bits == 16)) {
+            for (uint32_t i = 0; i < SIZEOF_HALF_DMA_BUFFER_IN_BYTES / 4; i++) {
+                for (uint8_t b = 0; b < sizeof(uint16_t); b++) {
+                    ringbuf_pop(&self->ring_buffer, &dma_buffer_p[i * 4 + b]);
+                    dma_buffer_p[i * 4 + b + 2] = dma_buffer_p[i * 4 + b]; // duplicated mono sample
+                }
+            }
+        } else if ((self->format == MONO) && (self->bits == 32)) {
+            for (uint32_t i = 0; i < SIZEOF_HALF_DMA_BUFFER_IN_BYTES / 8; i++) {
+                for (uint8_t b = 0; b < sizeof(uint32_t); b++) {
+                    ringbuf_pop(&self->ring_buffer, &dma_buffer_p[i * 8 + b]);
+                    dma_buffer_p[i * 8 + b + 4] = dma_buffer_p[i * 8 + b]; // duplicated mono sample
+                }
+            }
+        } else { // STEREO, both 16-bit and 32-bit
+            for (uint32_t i = 0; i < SIZEOF_HALF_DMA_BUFFER_IN_BYTES; i++) {
+                ringbuf_pop(&self->ring_buffer, &dma_buffer_p[i]);
+            }
+        }
+
+        // reformat 32 bit samples to match STM32 HAL API format
+        if (self->bits == 32) {
+            reformat_32_bit_samples((int32_t *)dma_buffer_p, SIZEOF_HALF_DMA_BUFFER_IN_BYTES / (sizeof(uint32_t)));
+        }
+    }
+
+    // flush cache to RAM so DMA can read the sample data
+    MP_HAL_CLEAN_DCACHE(dma_buffer_p, SIZEOF_HALF_DMA_BUFFER_IN_BYTES);
+}
+
+STATIC bool i2s_init(machine_i2s_obj_t *self) {
+
+    // init the GPIO lines
+    GPIO_InitTypeDef GPIO_InitStructure;
+    GPIO_InitStructure.Mode = GPIO_MODE_AF_PP;
+    GPIO_InitStructure.Speed = GPIO_SPEED_FAST;
+    GPIO_InitStructure.Pull = GPIO_PULLUP;
+
+    if (self->i2s_id == 1) {
+        self->hi2s.Instance = I2S1;
+        __SPI1_CLK_ENABLE();
+        // configure DMA streams
+        if (self->mode == I2S_MODE_MASTER_RX) {
+            self->dma_descr_rx = &dma_I2S_1_RX;
+        } else {
+            self->dma_descr_tx = &dma_I2S_1_TX;
+        }
+    } else if (self->i2s_id == 2) {
+        self->hi2s.Instance = I2S2;
+        __SPI2_CLK_ENABLE();
+        // configure DMA streams
+        if (self->mode == I2S_MODE_MASTER_RX) {
+            self->dma_descr_rx = &dma_I2S_2_RX;
+        } else {
+            self->dma_descr_tx = &dma_I2S_2_TX;
+        }
+    } else {
+        // invalid id number; should not get here as i2s object should not
+        // have been created without setting a valid i2s instance number
+        return false;
+    }
+
+    // GPIO Pin initialization
+    if (self->sck != MP_OBJ_TO_PTR(MP_OBJ_NULL)) {
+        GPIO_InitStructure.Pin = self->sck->pin_mask;
+        const pin_af_obj_t *af = pin_find_af(self->sck, AF_FN_I2S, self->i2s_id);
+        GPIO_InitStructure.Alternate = (uint8_t)af->idx;
+        HAL_GPIO_Init(self->sck->gpio, &GPIO_InitStructure);
+    }
+
+    if (self->ws != MP_OBJ_TO_PTR(MP_OBJ_NULL)) {
+        GPIO_InitStructure.Pin = self->ws->pin_mask;
+        const pin_af_obj_t *af = pin_find_af(self->ws, AF_FN_I2S, self->i2s_id);
+        GPIO_InitStructure.Alternate = (uint8_t)af->idx;
+        HAL_GPIO_Init(self->ws->gpio, &GPIO_InitStructure);
+    }
+
+    if (self->sd != MP_OBJ_TO_PTR(MP_OBJ_NULL)) {
+        GPIO_InitStructure.Pin = self->sd->pin_mask;
+        const pin_af_obj_t *af = pin_find_af(self->sd, AF_FN_I2S, self->i2s_id);
+        GPIO_InitStructure.Alternate = (uint8_t)af->idx;
+        HAL_GPIO_Init(self->sd->gpio, &GPIO_InitStructure);
+    }
+
+    if (HAL_I2S_Init(&self->hi2s) == HAL_OK) {
+        // Reset and initialize Tx and Rx DMA channels
+        if (self->mode == I2S_MODE_MASTER_RX) {
+            dma_invalidate_channel(self->dma_descr_rx);
+            dma_init(&self->hdma_rx, self->dma_descr_rx, DMA_PERIPH_TO_MEMORY, &self->hi2s);
+            self->hi2s.hdmarx = &self->hdma_rx;
+        } else {  // I2S_MODE_MASTER_TX
+            dma_invalidate_channel(self->dma_descr_tx);
+            dma_init(&self->hdma_tx, self->dma_descr_tx, DMA_MEMORY_TO_PERIPH, &self->hi2s);
+            self->hi2s.hdmatx = &self->hdma_tx;
+        }
+
+        __HAL_RCC_PLLI2S_ENABLE();  // start I2S clock
+
+        return true;
+    } else {
+        return false;
+    }
+
+}
+
+void HAL_I2S_ErrorCallback(I2S_HandleTypeDef *hi2s) {
+    uint32_t errorCode = HAL_I2S_GetError(hi2s);
+    printf("I2S Error = %ld\n", errorCode);
+}
+
+void HAL_I2S_RxCpltCallback(I2S_HandleTypeDef *hi2s) {
+    machine_i2s_obj_t *self;
+    if (hi2s->Instance == I2S1) {
+        self = machine_i2s_obj[0];
+    } else {
+        self = machine_i2s_obj[1];
+    }
+
+    // bottom half of buffer now filled,
+    // safe to empty the bottom half while the top half of buffer is being filled
+    empty_dma(self, BOTTOM_HALF);
+
+    // for non-blocking operation, this IRQ-based callback handles
+    // the readinto() method requests.
+    if ((self->io_mode == NON_BLOCKING) && (self->non_blocking_descriptor.copy_in_progress)) {
+        fill_appbuf_from_ringbuf_non_blocking(self);
+    }
+}
+
+void HAL_I2S_RxHalfCpltCallback(I2S_HandleTypeDef *hi2s) {
+    machine_i2s_obj_t *self;
+    if (hi2s->Instance == I2S1) {
+        self = machine_i2s_obj[0];
+    } else {
+        self = machine_i2s_obj[1];
+    }
+
+    // top half of buffer now filled,
+    // safe to empty the top half while the bottom half of buffer is being filled
+    empty_dma(self, TOP_HALF);
+
+    // for non-blocking operation, this IRQ-based callback handles
+    // the readinto() method requests.
+    if ((self->io_mode == NON_BLOCKING) && (self->non_blocking_descriptor.copy_in_progress)) {
+        fill_appbuf_from_ringbuf_non_blocking(self);
+    }
+}
+
+void HAL_I2S_TxCpltCallback(I2S_HandleTypeDef *hi2s) {
+    machine_i2s_obj_t *self;
+
+    if (hi2s->Instance == I2S1) {
+        self = machine_i2s_obj[0];
+    } else {
+        self = machine_i2s_obj[1];
+    }
+
+    // for non-blocking operation, this IRQ-based callback handles
+    // the write() method requests.
+    if ((self->io_mode == NON_BLOCKING) && (self->non_blocking_descriptor.copy_in_progress)) {
+        copy_appbuf_to_ringbuf_non_blocking(self);
+    }
+
+    // bottom half of buffer now emptied,
+    // safe to fill the bottom half while the top half of buffer is being emptied
+    feed_dma(self, BOTTOM_HALF);
+}
+
+void HAL_I2S_TxHalfCpltCallback(I2S_HandleTypeDef *hi2s) {
+    machine_i2s_obj_t *self;
+    if (hi2s->Instance == I2S1) {
+        self = machine_i2s_obj[0];
+    } else {
+        self = machine_i2s_obj[1];
+    }
+
+    // for non-blocking operation, this IRQ-based callback handles
+    // the write() method requests.
+    if ((self->io_mode == NON_BLOCKING) && (self->non_blocking_descriptor.copy_in_progress)) {
+        copy_appbuf_to_ringbuf_non_blocking(self);
+    }
+
+    // top half of buffer now emptied,
+    // safe to fill the top half while the bottom half of buffer is being emptied
+    feed_dma(self, TOP_HALF);
+}
+
+STATIC void machine_i2s_init_helper(machine_i2s_obj_t *self, size_t n_pos_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+
+    enum {
+        ARG_sck,
+        ARG_ws,
+        ARG_sd,
+        ARG_mode,
+        ARG_bits,
+        ARG_format,
+        ARG_rate,
+        ARG_ibuf,
+    };
+
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_sck,      MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_OBJ,   {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_ws,       MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_OBJ,   {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_sd,       MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_OBJ,   {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_mode,     MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT,   {.u_int = -1} },
+        { MP_QSTR_bits,     MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT,   {.u_int = -1} },
+        { MP_QSTR_format,   MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT,   {.u_int = -1} },
+        { MP_QSTR_rate,     MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT,   {.u_int = -1} },
+        { MP_QSTR_ibuf,     MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT,   {.u_int = -1} },
+    };
+
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_pos_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    memset(&self->hi2s, 0, sizeof(self->hi2s));
+
+    //
+    // ---- Check validity of arguments ----
+    //
+
+    // are I2S pin assignments valid?
+    const pin_af_obj_t *pin_af;
+
+    // is SCK valid?
+    if (mp_obj_is_type(args[ARG_sck].u_obj, &pin_type)) {
+        pin_af = pin_find_af(MP_OBJ_TO_PTR(args[ARG_sck].u_obj), AF_FN_I2S, self->i2s_id);
+        if (pin_af->type != AF_PIN_TYPE_I2S_CK) {
+            mp_raise_ValueError(MP_ERROR_TEXT("invalid SCK pin"));
+        }
+    } else {
+        mp_raise_ValueError(MP_ERROR_TEXT("SCK not a Pin type"));
+    }
+
+    // is WS valid?
+    if (mp_obj_is_type(args[ARG_ws].u_obj, &pin_type)) {
+        pin_af = pin_find_af(MP_OBJ_TO_PTR(args[ARG_ws].u_obj), AF_FN_I2S, self->i2s_id);
+        if (pin_af->type != AF_PIN_TYPE_I2S_WS) {
+            mp_raise_ValueError(MP_ERROR_TEXT("invalid WS pin"));
+        }
+    } else {
+        mp_raise_ValueError(MP_ERROR_TEXT("WS not a Pin type"));
+    }
+
+    // is SD valid?
+    if (mp_obj_is_type(args[ARG_sd].u_obj, &pin_type)) {
+        pin_af = pin_find_af(MP_OBJ_TO_PTR(args[ARG_sd].u_obj), AF_FN_I2S, self->i2s_id);
+        if (pin_af->type != AF_PIN_TYPE_I2S_SD) {
+            mp_raise_ValueError(MP_ERROR_TEXT("invalid SD pin"));
+        }
+    } else {
+        mp_raise_ValueError(MP_ERROR_TEXT("SD not a Pin type"));
+    }
+
+    // is Mode valid?
+    uint16_t i2s_mode = args[ARG_mode].u_int;
+    if ((i2s_mode != (I2S_MODE_MASTER_RX)) &&
+        (i2s_mode != (I2S_MODE_MASTER_TX))) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid mode"));
+    }
+
+    // is Bits valid?
+    int8_t i2s_bits = args[ARG_bits].u_int;
+    if ((i2s_bits != 16) &&
+        (i2s_bits != 32)) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid bits"));
+    }
+
+    // is Format valid?
+    format_t i2s_format = args[ARG_format].u_int;
+    if ((i2s_format != MONO) &&
+        (i2s_format != STEREO)) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid format"));
+    }
+
+    // is Rate valid?
+    // Not checked
+
+    // is Ibuf valid?
+    int32_t ring_buffer_len = args[ARG_ibuf].u_int;
+    if (ring_buffer_len > 0) {
+        uint8_t *buffer = m_new(uint8_t, ring_buffer_len);
+        self->ring_buffer_storage = buffer;
+        ringbuf_init(&self->ring_buffer, buffer, ring_buffer_len);
+    } else {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid ibuf"));
+    }
+
+    self->sck = MP_OBJ_TO_PTR(args[ARG_sck].u_obj);
+    self->ws = MP_OBJ_TO_PTR(args[ARG_ws].u_obj);
+    self->sd = MP_OBJ_TO_PTR(args[ARG_sd].u_obj);
+    self->mode = i2s_mode;
+    self->bits = i2s_bits;
+    self->format = i2s_format;
+    self->rate = args[ARG_rate].u_int;
+    self->ibuf = ring_buffer_len;
+    self->callback_for_non_blocking = MP_OBJ_NULL;
+    self->non_blocking_descriptor.copy_in_progress = false;
+    self->io_mode = BLOCKING;
+
+    I2S_InitTypeDef *init = &self->hi2s.Init;
+    init->Mode = i2s_mode;
+    init->Standard = I2S_STANDARD_PHILIPS;
+    init->DataFormat = get_dma_bits(self->mode, self->bits);
+    init->MCLKOutput = I2S_MCLKOUTPUT_DISABLE;
+    init->AudioFreq = args[ARG_rate].u_int;
+    init->CPOL = I2S_CPOL_LOW;
+    init->ClockSource = I2S_CLOCK_PLL;
+
+    // init the I2S bus
+    if (!i2s_init(self)) {
+        mp_raise_msg_varg(&mp_type_OSError, MP_ERROR_TEXT("I2S init failed"));
+    }
+
+    // start DMA.  DMA is configured to run continuously, using a circular buffer configuration
+    uint32_t number_of_samples = 0;
+    if (init->DataFormat == I2S_DATAFORMAT_16B) {
+        number_of_samples = SIZEOF_DMA_BUFFER_IN_BYTES / sizeof(uint16_t);
+    } else {  // 32 bits
+        number_of_samples = SIZEOF_DMA_BUFFER_IN_BYTES / sizeof(uint32_t);
+    }
+
+    HAL_StatusTypeDef status;
+    if (self->mode == I2S_MODE_MASTER_TX) {
+        status = HAL_I2S_Transmit_DMA(&self->hi2s, (void *)self->dma_buffer_dcache_aligned, number_of_samples);
+    } else {  // RX
+        status = HAL_I2S_Receive_DMA(&self->hi2s, (void *)self->dma_buffer_dcache_aligned, number_of_samples);
+    }
+
+    if (status != HAL_OK) {
+        mp_raise_msg_varg(&mp_type_OSError, MP_ERROR_TEXT("DMA init failed"));
+    }
+}
+
+STATIC void machine_i2s_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_printf(print, "I2S(id=%u,\n"
+        "sck="MP_HAL_PIN_FMT ",\n"
+        "ws="MP_HAL_PIN_FMT ",\n"
+        "sd="MP_HAL_PIN_FMT ",\n"
+        "mode=%u,\n"
+        "bits=%u, format=%u,\n"
+        "rate=%d, ibuf=%d)",
+        self->i2s_id,
+        mp_hal_pin_name(self->sck),
+        mp_hal_pin_name(self->ws),
+        mp_hal_pin_name(self->sd),
+        self->mode,
+        self->bits, self->format,
+        self->rate, self->ibuf
+        );
+}
+
+STATIC mp_obj_t machine_i2s_make_new(const mp_obj_type_t *type, size_t n_pos_args, size_t n_kw_args, const mp_obj_t *args) {
+    mp_arg_check_num(n_pos_args, n_kw_args, 1, MP_OBJ_FUN_ARGS_MAX, true);
+    uint8_t i2s_id = mp_obj_get_int(args[0]);
+    uint8_t i2s_id_zero_base = 0;
+
+    if (0) {
+    #ifdef MICROPY_HW_I2S1
+    } else if (i2s_id == 1) {
+        i2s_id_zero_base = 0;
+    #endif
+    #ifdef MICROPY_HW_I2S2
+    } else if (i2s_id == 2) {
+        i2s_id_zero_base = 1;
+    #endif
+    } else {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid id"));
+    }
+
+    machine_i2s_obj_t *self;
+    if (machine_i2s_obj[i2s_id_zero_base] == NULL) {
+        self = m_new_obj(machine_i2s_obj_t);
+        machine_i2s_obj[i2s_id_zero_base] = self;
+        self->base.type = &machine_i2s_type;
+        self->i2s_id = i2s_id;
+    } else {
+        self = machine_i2s_obj[i2s_id_zero_base];
+        machine_i2s_deinit(MP_OBJ_FROM_PTR(self));
+    }
+
+    // align DMA buffer start to the cache line size (32 bytes)
+    self->dma_buffer_dcache_aligned = (uint8_t *)((uint32_t)(self->dma_buffer + 0x1f) & ~0x1f);
+
+    mp_map_t kw_args;
+    mp_map_init_fixed_table(&kw_args, n_kw_args, args + n_pos_args);
+    machine_i2s_init_helper(self, n_pos_args - 1, args + 1, &kw_args);
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC mp_obj_t machine_i2s_init(size_t n_pos_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
+    machine_i2s_deinit(MP_OBJ_FROM_PTR(self));
+    machine_i2s_init_helper(self, n_pos_args - 1, pos_args + 1, kw_args);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(machine_i2s_init_obj, 1, machine_i2s_init);
+
+STATIC mp_obj_t machine_i2s_deinit(mp_obj_t self_in) {
+
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+
+    dma_deinit(self->dma_descr_tx);
+    dma_deinit(self->dma_descr_rx);
+    HAL_I2S_DeInit(&self->hi2s);
+
+    if (self->hi2s.Instance == I2S1) {
+        __SPI1_FORCE_RESET();
+        __SPI1_RELEASE_RESET();
+        __SPI1_CLK_DISABLE();
+    } else if (self->hi2s.Instance == I2S2) {
+        __SPI2_FORCE_RESET();
+        __SPI2_RELEASE_RESET();
+        __SPI2_CLK_DISABLE();
+    }
+
+    m_free(self->ring_buffer_storage);
+
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_i2s_deinit_obj, machine_i2s_deinit);
+
+STATIC mp_obj_t machine_i2s_irq(mp_obj_t self_in, mp_obj_t handler) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    if (handler != mp_const_none && !mp_obj_is_callable(handler)) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid callback"));
+    }
+
+    if (handler != mp_const_none) {
+        self->io_mode = NON_BLOCKING;
+    } else {
+        self->io_mode = BLOCKING;
+    }
+
+    self->callback_for_non_blocking = handler;
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(machine_i2s_irq_obj, machine_i2s_irq);
+
+// Shift() is typically used as a volume control.
+// shift=1 increases volume by 6dB, shift=-1 decreases volume by 6dB
+STATIC mp_obj_t machine_i2s_shift(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_buf, ARG_bits, ARG_shift};
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_buf,    MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_bits,   MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_shift, MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+    };
+
+    // parse args
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(args[ARG_buf].u_obj, &bufinfo, MP_BUFFER_RW);
+
+    int16_t *buf_16 = bufinfo.buf;
+    int32_t *buf_32 = bufinfo.buf;
+
+    uint8_t bits = args[ARG_bits].u_int;
+    int8_t shift = args[ARG_shift].u_int;
+
+    uint32_t num_audio_samples;
+    switch (bits) {
+        case 16:
+            num_audio_samples = bufinfo.len / sizeof(uint16_t);
+            break;
+
+        case 32:
+            num_audio_samples = bufinfo.len / sizeof(uint32_t);
+            break;
+
+        default:
+            mp_raise_ValueError(MP_ERROR_TEXT("invalid bits"));
+            break;
+    }
+
+    for (uint32_t i = 0; i < num_audio_samples; i++) {
+        switch (bits) {
+            case 16:
+                if (shift >= 0) {
+                    buf_16[i] = buf_16[i] << shift;
+                } else {
+                    buf_16[i] = buf_16[i] >> abs(shift);
+                }
+                break;
+            case 32:
+                if (shift >= 0) {
+                    buf_32[i] = buf_32[i] << shift;
+                } else {
+                    buf_32[i] = buf_32[i] >> abs(shift);
+                }
+                break;
+        }
+    }
+
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(machine_i2s_shift_fun_obj, 0, machine_i2s_shift);
+STATIC MP_DEFINE_CONST_STATICMETHOD_OBJ(machine_i2s_shift_obj, MP_ROM_PTR(&machine_i2s_shift_fun_obj));
+
+STATIC const mp_rom_map_elem_t machine_i2s_locals_dict_table[] = {
+    // Methods
+    { MP_ROM_QSTR(MP_QSTR_init),            MP_ROM_PTR(&machine_i2s_init_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readinto),        MP_ROM_PTR(&mp_stream_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_write),           MP_ROM_PTR(&mp_stream_write_obj) },
+    { MP_ROM_QSTR(MP_QSTR_deinit),          MP_ROM_PTR(&machine_i2s_deinit_obj) },
+    { MP_ROM_QSTR(MP_QSTR_irq),             MP_ROM_PTR(&machine_i2s_irq_obj) },
+
+    // Static method
+    { MP_ROM_QSTR(MP_QSTR_shift),           MP_ROM_PTR(&machine_i2s_shift_obj) },
+
+    // Constants
+    { MP_ROM_QSTR(MP_QSTR_RX),              MP_ROM_INT(I2S_MODE_MASTER_RX) },
+    { MP_ROM_QSTR(MP_QSTR_TX),              MP_ROM_INT(I2S_MODE_MASTER_TX) },
+    { MP_ROM_QSTR(MP_QSTR_STEREO),          MP_ROM_INT(STEREO) },
+    { MP_ROM_QSTR(MP_QSTR_MONO),            MP_ROM_INT(MONO) },
+};
+MP_DEFINE_CONST_DICT(machine_i2s_locals_dict, machine_i2s_locals_dict_table);
+
+STATIC mp_uint_t machine_i2s_stream_read(mp_obj_t self_in, void *buf_in, mp_uint_t size, int *errcode) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+
+    if (self->mode != I2S_MODE_MASTER_RX) {
+        *errcode = MP_EPERM;
+        return MP_STREAM_ERROR;
+    }
+
+    uint8_t appbuf_sample_size_in_bytes = (self->bits / 8) * (self->format == STEREO ? 2: 1);
+    if (size % appbuf_sample_size_in_bytes != 0) {
+        *errcode = MP_EINVAL;
+        return MP_STREAM_ERROR;
+    }
+
+    if (size == 0) {
+        return 0;
+    }
+
+    if (self->io_mode == NON_BLOCKING) {
+        self->non_blocking_descriptor.appbuf.buf = (void *)buf_in;
+        self->non_blocking_descriptor.appbuf.len = size;
+        self->non_blocking_descriptor.index = 0;
+        self->non_blocking_descriptor.copy_in_progress = true;
+        return size;
+    } else { // blocking or uasyncio mode
+        mp_buffer_info_t appbuf;
+        appbuf.buf = (void *)buf_in;
+        appbuf.len = size;
+        uint32_t num_bytes_read = fill_appbuf_from_ringbuf(self, &appbuf);
+        return num_bytes_read;
+    }
+}
+
+STATIC mp_uint_t machine_i2s_stream_write(mp_obj_t self_in, const void *buf_in, mp_uint_t size, int *errcode) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+
+    if (self->mode != I2S_MODE_MASTER_TX) {
+        *errcode = MP_EPERM;
+        return MP_STREAM_ERROR;
+    }
+
+    if (size == 0) {
+        return 0;
+    }
+
+    if (self->io_mode == NON_BLOCKING) {
+        self->non_blocking_descriptor.appbuf.buf = (void *)buf_in;
+        self->non_blocking_descriptor.appbuf.len = size;
+        self->non_blocking_descriptor.index = 0;
+        self->non_blocking_descriptor.copy_in_progress = true;
+        return size;
+    } else { // blocking or uasyncio mode
+        mp_buffer_info_t appbuf;
+        appbuf.buf = (void *)buf_in;
+        appbuf.len = size;
+        uint32_t num_bytes_written = copy_appbuf_to_ringbuf(self, &appbuf);
+        return num_bytes_written;
+    }
+}
+
+STATIC mp_uint_t machine_i2s_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_t arg, int *errcode) {
+    machine_i2s_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_uint_t ret;
+    uintptr_t flags = arg;
+    self->io_mode = UASYNCIO; // a call to ioctl() is an indication that uasyncio is being used
+
+    if (request == MP_STREAM_POLL) {
+        ret = 0;
+
+        if (flags & MP_STREAM_POLL_RD) {
+            if (self->mode != I2S_MODE_MASTER_RX) {
+                *errcode = MP_EPERM;
+                return MP_STREAM_ERROR;
+            }
+
+            if (!ringbuf_is_empty(&self->ring_buffer)) {
+                ret |= MP_STREAM_POLL_RD;
+            }
+        }
+
+        if (flags & MP_STREAM_POLL_WR) {
+            if (self->mode != I2S_MODE_MASTER_TX) {
+                *errcode = MP_EPERM;
+                return MP_STREAM_ERROR;
+            }
+
+            if (!ringbuf_is_full(&self->ring_buffer)) {
+                ret |= MP_STREAM_POLL_WR;
+            }
+        }
+    } else {
+        *errcode = MP_EINVAL;
+        ret = MP_STREAM_ERROR;
+    }
+
+    return ret;
+}
+
+STATIC const mp_stream_p_t i2s_stream_p = {
+    .read = machine_i2s_stream_read,
+    .write = machine_i2s_stream_write,
+    .ioctl = machine_i2s_ioctl,
+    .is_text = false,
+};
+
+const mp_obj_type_t machine_i2s_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_I2S,
+    .print = machine_i2s_print,
+    .getiter = mp_identity_getiter,
+    .iternext = mp_stream_unbuffered_iter,
+    .protocol = &i2s_stream_p,
+    .make_new = machine_i2s_make_new,
+    .locals_dict = (mp_obj_dict_t *)&machine_i2s_locals_dict,
+};
+
+#endif // MICROPY_HW_ENABLE_I2S
diff --git a/ports/stm32/machine_uart.c b/ports/stm32/machine_uart.c
index 1b8db2e3e..354a1e26a 100644
--- a/ports/stm32/machine_uart.c
+++ b/ports/stm32/machine_uart.c
@@ -32,8 +32,8 @@
 #include "py/stream.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"
-#include "lib/utils/interrupt_char.h"
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/interrupt_char.h"
+#include "shared/runtime/mpirq.h"
 #include "uart.h"
 #include "irq.h"
 #include "pendsv.h"
diff --git a/ports/stm32/main.c b/ports/stm32/main.c
index 6df7374cc..d55f1a2c3 100644
--- a/ports/stm32/main.c
+++ b/ports/stm32/main.c
@@ -32,8 +32,8 @@
 #include "py/gc.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"
-#include "lib/mp-readline/readline.h"
-#include "lib/utils/pyexec.h"
+#include "shared/readline/readline.h"
+#include "shared/runtime/pyexec.h"
 #include "lib/oofatfs/ff.h"
 #include "lib/littlefs/lfs1.h"
 #include "lib/littlefs/lfs1_util.h"
@@ -404,7 +404,7 @@ void stm32_main(uint32_t reset_mode) {
     bool sdram_valid = true;
     UNUSED(sdram_valid);
     #if MICROPY_HW_SDRAM_STARTUP_TEST
-    sdram_valid = sdram_test(true);
+    sdram_valid = sdram_test(false);
     #endif
     #endif
     #if MICROPY_PY_THREAD
@@ -527,6 +527,10 @@ soft_reset:
     pyb_usb_init0();
     #endif
 
+    #if MICROPY_HW_ENABLE_I2S
+    machine_i2s_init0();
+    #endif
+
     // Initialise the local flash filesystem.
     // Create it if needed, mount in on /flash, and set it as current dir.
     bool mounted_flash = false;
@@ -578,13 +582,13 @@ soft_reset:
     // init USB device to default setting if it was not already configured
     if (!(pyb_usb_flags & PYB_USB_FLAG_USB_MODE_CALLED)) {
         #if MICROPY_HW_USB_MSC
-        const uint16_t pid = USBD_PID_CDC_MSC;
+        const uint16_t pid = MICROPY_HW_USB_PID_CDC_MSC;
         const uint8_t mode = USBD_MODE_CDC_MSC;
         #else
-        const uint16_t pid = USBD_PID_CDC;
+        const uint16_t pid = MICROPY_HW_USB_PID_CDC;
         const uint8_t mode = USBD_MODE_CDC;
         #endif
-        pyb_usb_dev_init(pyb_usb_dev_detect(), USBD_VID, pid, mode, 0, NULL, NULL);
+        pyb_usb_dev_init(pyb_usb_dev_detect(), MICROPY_HW_USB_VID, pid, mode, 0, NULL, NULL);
     }
     #endif
 
diff --git a/ports/stm32/mbedtls/mbedtls_port.c b/ports/stm32/mbedtls/mbedtls_port.c
index efb8d2c2a..c31eb744a 100644
--- a/ports/stm32/mbedtls/mbedtls_port.c
+++ b/ports/stm32/mbedtls/mbedtls_port.c
@@ -80,7 +80,7 @@ void m_free_mbedtls(void *ptr_in) {
 }
 
 int mbedtls_hardware_poll(void *data, unsigned char *output, size_t len, size_t *olen) {
-    uint32_t val;
+    uint32_t val = 0;
     int n = 0;
     *olen = len;
     while (len--) {
diff --git a/ports/stm32/mboot/Makefile b/ports/stm32/mboot/Makefile
index 17de685a6..553fc4ac6 100755
--- a/ports/stm32/mboot/Makefile
+++ b/ports/stm32/mboot/Makefile
@@ -105,19 +105,19 @@ else
 COPT += -Os -DNDEBUG
 endif
 
-$(BUILD)/lib/libc/string0.o: CFLAGS += $(CFLAGS_BUILTIN)
+$(BUILD)/shared/libc/string0.o: CFLAGS += $(CFLAGS_BUILTIN)
 LIB_SRC_C += \
-	lib/libc/string0.c \
+	shared/libc/string0.c \
 	lib/littlefs/lfs1.c \
 	lib/littlefs/lfs1_util.c \
 	lib/littlefs/lfs2.c \
 	lib/littlefs/lfs2_util.c \
 	lib/oofatfs/ff.c \
 	lib/oofatfs/ffunicode.c \
-	extmod/uzlib/crc32.c \
-	extmod/uzlib/adler32.c \
-	extmod/uzlib/tinflate.c \
-	extmod/uzlib/tinfgzip.c
+	lib/uzlib/adler32.c \
+	lib/uzlib/crc32.c \
+	lib/uzlib/tinfgzip.c \
+	lib/uzlib/tinflate.c
 
 SRC_C += \
 	main.c \
diff --git a/ports/stm32/mboot/gzstream.c b/ports/stm32/mboot/gzstream.c
index 652302e42..6ed8a21d9 100644
--- a/ports/stm32/mboot/gzstream.c
+++ b/ports/stm32/mboot/gzstream.c
@@ -27,7 +27,7 @@
 #include <string.h>
 
 #include "py/mphal.h"
-#include "extmod/uzlib/uzlib.h"
+#include "lib/uzlib/uzlib.h"
 #include "gzstream.h"
 #include "mboot.h"
 
diff --git a/ports/stm32/mboot/main.c b/ports/stm32/mboot/main.c
index c1e1d59d2..6c7d2c771 100644
--- a/ports/stm32/mboot/main.c
+++ b/ports/stm32/mboot/main.c
@@ -28,7 +28,7 @@
 #include <string.h>
 
 #include "py/mphal.h"
-#include "extmod/crypto-algorithms/sha256.c"
+#include "lib/crypto-algorithms/sha256.c"
 #include "boardctrl.h"
 #include "usbd_core.h"
 #include "storage.h"
diff --git a/ports/stm32/modmachine.c b/ports/stm32/modmachine.c
index aee563ee8..92b80b365 100644
--- a/ports/stm32/modmachine.c
+++ b/ports/stm32/modmachine.c
@@ -33,12 +33,13 @@
 #include "py/objstr.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"
+#include "extmod/machine_bitstream.h"
 #include "extmod/machine_mem.h"
 #include "extmod/machine_signal.h"
 #include "extmod/machine_pulse.h"
 #include "extmod/machine_i2c.h"
 #include "extmod/machine_spi.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 #include "lib/oofatfs/ff.h"
 #include "extmod/vfs.h"
 #include "extmod/vfs_fat.h"
@@ -406,6 +407,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_disable_irq),         MP_ROM_PTR(&machine_disable_irq_obj) },
     { MP_ROM_QSTR(MP_QSTR_enable_irq),          MP_ROM_PTR(&machine_enable_irq_obj) },
 
+    #if MICROPY_PY_MACHINE_BITSTREAM
+    { MP_ROM_QSTR(MP_QSTR_bitstream),           MP_ROM_PTR(&machine_bitstream_obj) },
+    #endif
     #if MICROPY_PY_MACHINE_PULSE
     { MP_ROM_QSTR(MP_QSTR_time_pulse_us),       MP_ROM_PTR(&machine_time_pulse_us_obj) },
     #endif
@@ -431,6 +435,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_SPI),                 MP_ROM_PTR(&machine_hard_spi_type) },
     { MP_ROM_QSTR(MP_QSTR_SoftSPI),             MP_ROM_PTR(&mp_machine_soft_spi_type) },
     #endif
+    #if MICROPY_HW_ENABLE_I2S
+    { MP_ROM_QSTR(MP_QSTR_I2S),                 MP_ROM_PTR(&machine_i2s_type) },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_UART),                MP_ROM_PTR(&pyb_uart_type) },
     { MP_ROM_QSTR(MP_QSTR_WDT),                 MP_ROM_PTR(&pyb_wdt_type) },
     { MP_ROM_QSTR(MP_QSTR_Timer),               MP_ROM_PTR(&machine_timer_type) },
@@ -461,4 +468,3 @@ const mp_obj_module_t machine_module = {
     .base = { &mp_type_module },
     .globals = (mp_obj_dict_t *)&machine_module_globals,
 };
-
diff --git a/ports/stm32/modmachine.h b/ports/stm32/modmachine.h
index e84620854..0e6c000a8 100644
--- a/ports/stm32/modmachine.h
+++ b/ports/stm32/modmachine.h
@@ -31,9 +31,11 @@
 extern const mp_obj_type_t machine_adc_type;
 extern const mp_obj_type_t machine_timer_type;
 extern const mp_obj_type_t machine_hard_i2c_type;
+extern const mp_obj_type_t machine_i2s_type;
 
 void machine_init(void);
 void machine_deinit(void);
+void machine_i2s_init0();
 
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(machine_info_obj);
 MP_DECLARE_CONST_FUN_OBJ_0(machine_unique_id_obj);
diff --git a/ports/stm32/modnetwork.c b/ports/stm32/modnetwork.c
index 4279df088..06c4eb05d 100644
--- a/ports/stm32/modnetwork.c
+++ b/ports/stm32/modnetwork.c
@@ -31,7 +31,7 @@
 #include "py/objlist.h"
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "systick.h"
 #include "pendsv.h"
 #include "modnetwork.h"
diff --git a/ports/stm32/modnwcc3k.c b/ports/stm32/modnwcc3k.c
index b52958ba2..07178b65c 100644
--- a/ports/stm32/modnwcc3k.c
+++ b/ports/stm32/modnwcc3k.c
@@ -36,7 +36,7 @@
 #include "py/runtime.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "modnetwork.h"
 #include "pin.h"
 #include "spi.h"
diff --git a/ports/stm32/modnwwiznet5k.c b/ports/stm32/modnwwiznet5k.c
index 204b9fcc3..1e18d03ca 100644
--- a/ports/stm32/modnwwiznet5k.c
+++ b/ports/stm32/modnwwiznet5k.c
@@ -33,7 +33,7 @@
 #include "py/stream.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "modnetwork.h"
 #include "pin.h"
 #include "spi.h"
diff --git a/ports/stm32/modpyb.c b/ports/stm32/modpyb.c
index c92090699..b9e2bac03 100644
--- a/ports/stm32/modpyb.c
+++ b/ports/stm32/modpyb.c
@@ -29,7 +29,7 @@
 
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 #include "drivers/dht/dht.h"
 #include "stm32_it.h"
 #include "irq.h"
diff --git a/ports/stm32/moduos.c b/ports/stm32/moduos.c
index 6f9740c64..5b2335272 100644
--- a/ports/stm32/moduos.c
+++ b/ports/stm32/moduos.c
@@ -30,7 +30,7 @@
 #include "py/runtime.h"
 #include "py/objtuple.h"
 #include "py/objstr.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "lib/oofatfs/ff.h"
 #include "lib/oofatfs/diskio.h"
 #include "extmod/misc.h"
diff --git a/ports/stm32/modusocket.c b/ports/stm32/modusocket.c
index 2732d472b..c59fc8522 100644
--- a/ports/stm32/modusocket.c
+++ b/ports/stm32/modusocket.c
@@ -32,7 +32,7 @@
 #include "py/runtime.h"
 #include "py/stream.h"
 #include "py/mperrno.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "modnetwork.h"
 
 #if MICROPY_PY_USOCKET && !MICROPY_PY_LWIP
diff --git a/ports/stm32/modutime.c b/ports/stm32/modutime.c
index 4bce45eb3..1a22c34b6 100644
--- a/ports/stm32/modutime.c
+++ b/ports/stm32/modutime.c
@@ -30,7 +30,7 @@
 #include "py/runtime.h"
 #include "py/smallint.h"
 #include "py/obj.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "extmod/utime_mphal.h"
 #include "systick.h"
 #include "portmodules.h"
diff --git a/ports/stm32/mpbthciport.c b/ports/stm32/mpbthciport.c
index accb913e1..369c91e30 100644
--- a/ports/stm32/mpbthciport.c
+++ b/ports/stm32/mpbthciport.c
@@ -31,7 +31,7 @@
 #include "mpbthciport.h"
 #include "softtimer.h"
 #include "pendsv.h"
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/mpirq.h"
 
 #if MICROPY_PY_BLUETOOTH
 
diff --git a/ports/stm32/mpconfigboard_common.h b/ports/stm32/mpconfigboard_common.h
index ce9dbdb0a..0cf6adce3 100644
--- a/ports/stm32/mpconfigboard_common.h
+++ b/ports/stm32/mpconfigboard_common.h
@@ -177,6 +177,87 @@
 #define MICROPY_HW_UART_IS_RESERVED(uart_id) (false)
 #endif
 
+/*****************************************************************************/
+// USB configuration
+
+// The USBD_xxx macros have been renamed to MICROPY_HW_USB_xxx.
+#if defined(USBD_VID) \
+    || defined(USBD_LANGID_STRING) \
+    || defined(USBD_MANUFACTURER_STRING) \
+    || defined(USBD_PRODUCT_HS_STRING) \
+    || defined(USBD_PRODUCT_FS_STRING) \
+    || defined(USBD_CONFIGURATION_HS_STRING) \
+    || defined(USBD_INTERFACE_HS_STRING) \
+    || defined(USBD_CONFIGURATION_FS_STRING) \
+    || defined(USBD_INTERFACE_FS_STRING) \
+    || defined(USBD_CDC_RX_DATA_SIZE) \
+    || defined(USBD_CDC_TX_DATA_SIZE)
+#error "Old USBD_xxx configuration option used, renamed to MICROPY_HW_USB_xxx"
+#endif
+
+// Default VID and PID values to use for the USB device.  If MICROPY_HW_USB_VID
+// is defined by a board then all needed PID options must also be defined.  The
+// VID and PID can also be set dynamically in pyb.usb_mode().
+// Windows needs a different PID to distinguish different device configurations.
+#ifndef MICROPY_HW_USB_VID
+#define MICROPY_HW_USB_VID              (0xf055)
+#define MICROPY_HW_USB_PID_CDC_MSC      (0x9800)
+#define MICROPY_HW_USB_PID_CDC_HID      (0x9801)
+#define MICROPY_HW_USB_PID_CDC          (0x9802)
+#define MICROPY_HW_USB_PID_MSC          (0x9803)
+#define MICROPY_HW_USB_PID_CDC2_MSC     (0x9804)
+#define MICROPY_HW_USB_PID_CDC2         (0x9805)
+#define MICROPY_HW_USB_PID_CDC3         (0x9806)
+#define MICROPY_HW_USB_PID_CDC3_MSC     (0x9807)
+#define MICROPY_HW_USB_PID_CDC_MSC_HID  (0x9808)
+#define MICROPY_HW_USB_PID_CDC2_MSC_HID (0x9809)
+#define MICROPY_HW_USB_PID_CDC3_MSC_HID (0x980a)
+#endif
+
+#ifndef MICROPY_HW_USB_LANGID_STRING
+#define MICROPY_HW_USB_LANGID_STRING            0x409
+#endif
+
+#ifndef MICROPY_HW_USB_MANUFACTURER_STRING
+#define MICROPY_HW_USB_MANUFACTURER_STRING      "MicroPython"
+#endif
+
+#ifndef MICROPY_HW_USB_PRODUCT_HS_STRING
+#define MICROPY_HW_USB_PRODUCT_HS_STRING        "Pyboard Virtual Comm Port in HS Mode"
+#endif
+
+#ifndef MICROPY_HW_USB_PRODUCT_FS_STRING
+#define MICROPY_HW_USB_PRODUCT_FS_STRING        "Pyboard Virtual Comm Port in FS Mode"
+#endif
+
+#ifndef MICROPY_HW_USB_CONFIGURATION_HS_STRING
+#define MICROPY_HW_USB_CONFIGURATION_HS_STRING  "Pyboard Config"
+#endif
+
+#ifndef MICROPY_HW_USB_INTERFACE_HS_STRING
+#define MICROPY_HW_USB_INTERFACE_HS_STRING      "Pyboard Interface"
+#endif
+
+#ifndef MICROPY_HW_USB_CONFIGURATION_FS_STRING
+#define MICROPY_HW_USB_CONFIGURATION_FS_STRING  "Pyboard Config"
+#endif
+
+#ifndef MICROPY_HW_USB_INTERFACE_FS_STRING
+#define MICROPY_HW_USB_INTERFACE_FS_STRING      "Pyboard Interface"
+#endif
+
+// Amount of incoming buffer space for each CDC instance.
+// This must be 2 or greater, and a power of 2.
+#ifndef MICROPY_HW_USB_CDC_RX_DATA_SIZE
+#define MICROPY_HW_USB_CDC_RX_DATA_SIZE (1024)
+#endif
+
+// Amount of outgoing buffer space for each CDC instance.
+// This must be a power of 2 and no greater than 16384.
+#ifndef MICROPY_HW_USB_CDC_TX_DATA_SIZE
+#define MICROPY_HW_USB_CDC_TX_DATA_SIZE (1024)
+#endif
+
 /*****************************************************************************/
 // General configuration
 
diff --git a/ports/stm32/mpconfigport.h b/ports/stm32/mpconfigport.h
index 6e341f34d..b6b34e0a7 100644
--- a/ports/stm32/mpconfigport.h
+++ b/ports/stm32/mpconfigport.h
@@ -56,7 +56,9 @@
 #define MICROPY_COMP_RETURN_IF_EXPR (1)
 
 // optimisations
+#ifndef MICROPY_OPT_COMPUTED_GOTO
 #define MICROPY_OPT_COMPUTED_GOTO   (1)
+#endif
 #define MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE (0)
 #define MICROPY_OPT_MPZ_BITWISE     (1)
 #define MICROPY_OPT_MATH_FACTORIAL  (1)
@@ -91,6 +93,9 @@
 #define MICROPY_PY_FUNCTION_ATTRS   (1)
 #define MICROPY_PY_DESCRIPTORS      (1)
 #define MICROPY_PY_DELATTR_SETATTR  (1)
+#ifndef MICROPY_PY_FSTRINGS
+#define MICROPY_PY_FSTRINGS         (1)
+#endif
 #define MICROPY_PY_BUILTINS_STR_UNICODE (1)
 #define MICROPY_PY_BUILTINS_STR_CENTER (1)
 #define MICROPY_PY_BUILTINS_STR_PARTITION (1)
@@ -190,6 +195,9 @@
 #define MICROPY_PY_LWIP_SOCK_RAW    (MICROPY_PY_LWIP)
 #ifndef MICROPY_PY_MACHINE
 #define MICROPY_PY_MACHINE          (1)
+#ifndef MICROPY_PY_MACHINE_BITSTREAM
+#define MICROPY_PY_MACHINE_BITSTREAM (1)
+#endif
 #define MICROPY_PY_MACHINE_PULSE    (1)
 #define MICROPY_PY_MACHINE_PIN_MAKE_NEW mp_pin_make_new
 #define MICROPY_PY_MACHINE_I2C      (1)
diff --git a/ports/stm32/mphalport.c b/ports/stm32/mphalport.c
index 0e40911ed..81e84ef93 100644
--- a/ports/stm32/mphalport.c
+++ b/ports/stm32/mphalport.c
@@ -53,10 +53,6 @@ MP_WEAK int mp_hal_stdin_rx_chr(void) {
     }
 }
 
-void mp_hal_stdout_tx_str(const char *str) {
-    mp_hal_stdout_tx_strn(str, strlen(str));
-}
-
 MP_WEAK void mp_hal_stdout_tx_strn(const char *str, size_t len) {
     if (MP_STATE_PORT(pyb_stdio_uart) != NULL) {
         uart_tx_strn(MP_STATE_PORT(pyb_stdio_uart), str, len);
@@ -67,26 +63,6 @@ MP_WEAK void mp_hal_stdout_tx_strn(const char *str, size_t len) {
     mp_uos_dupterm_tx_strn(str, len);
 }
 
-// Efficiently convert "\n" to "\r\n"
-void mp_hal_stdout_tx_strn_cooked(const char *str, size_t len) {
-    const char *last = str;
-    while (len--) {
-        if (*str == '\n') {
-            if (str > last) {
-                mp_hal_stdout_tx_strn(last, str - last);
-            }
-            mp_hal_stdout_tx_strn("\r\n", 2);
-            ++str;
-            last = str;
-        } else {
-            ++str;
-        }
-    }
-    if (str > last) {
-        mp_hal_stdout_tx_strn(last, str - last);
-    }
-}
-
 #if __CORTEX_M >= 0x03
 void mp_hal_ticks_cpu_enable(void) {
     if (!(DWT->CTRL & DWT_CTRL_CYCCNTENA_Msk)) {
diff --git a/ports/stm32/network_wiznet5k.c b/ports/stm32/network_wiznet5k.c
index c85ef5e88..bd4c02cb0 100644
--- a/ports/stm32/network_wiznet5k.c
+++ b/ports/stm32/network_wiznet5k.c
@@ -34,7 +34,7 @@
 
 #if MICROPY_PY_WIZNET5K && MICROPY_PY_LWIP
 
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 #include "drivers/wiznet5k/ethernet/socket.h"
 #include "lwip/err.h"
 #include "lwip/dns.h"
diff --git a/ports/stm32/pendsv.c b/ports/stm32/pendsv.c
index c5b2fcf92..d4c4496f1 100644
--- a/ports/stm32/pendsv.c
+++ b/ports/stm32/pendsv.c
@@ -27,7 +27,7 @@
 #include <stdlib.h>
 
 #include "py/runtime.h"
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 #include "pendsv.h"
 #include "irq.h"
 
diff --git a/ports/stm32/pin_defs_stm32.c b/ports/stm32/pin_defs_stm32.c
index a3f9d039d..070005d21 100644
--- a/ports/stm32/pin_defs_stm32.c
+++ b/ports/stm32/pin_defs_stm32.c
@@ -28,4 +28,3 @@ uint32_t pin_get_pull(const pin_obj_t *pin) {
 uint32_t pin_get_af(const pin_obj_t *pin) {
     return (pin->gpio->AFR[pin->pin >> 3] >> ((pin->pin & 7) * 4)) & 0xf;
 }
-
diff --git a/ports/stm32/pin_defs_stm32.h b/ports/stm32/pin_defs_stm32.h
index 9285c190a..20faab4e0 100644
--- a/ports/stm32/pin_defs_stm32.h
+++ b/ports/stm32/pin_defs_stm32.h
@@ -109,6 +109,7 @@ enum {
 // some #defines to massage things. Also I2S and SPI share the same
 // peripheral.
 
+#define GPIO_AF5_I2S1   GPIO_AF5_SPI1
 #define GPIO_AF5_I2S2   GPIO_AF5_SPI2
 #define GPIO_AF5_I2S3   GPIO_AF5_I2S3ext
 #define GPIO_AF6_I2S2   GPIO_AF6_I2S2ext
@@ -116,6 +117,7 @@ enum {
 #define GPIO_AF7_I2S2   GPIO_AF7_SPI2
 #define GPIO_AF7_I2S3   GPIO_AF7_I2S3ext
 
+#define I2S1  SPI1
 #define I2S2  SPI2
 #define I2S3  SPI3
 
@@ -134,4 +136,3 @@ enum {
 };
 
 typedef GPIO_TypeDef pin_gpio_t;
-
diff --git a/ports/stm32/powerctrl.c b/ports/stm32/powerctrl.c
index 253f1056c..137312ade 100644
--- a/ports/stm32/powerctrl.c
+++ b/ports/stm32/powerctrl.c
@@ -519,10 +519,103 @@ set_clk:
 
 #elif defined(STM32WB)
 
+#include "stm32wbxx_ll_utils.h"
+
+#define LPR_THRESHOLD (2000000)
+#define VOS2_THRESHOLD (16000000)
+
+enum {
+    SYSCLK_MODE_NONE,
+    SYSCLK_MODE_MSI,
+    SYSCLK_MODE_HSE_64M,
+};
+
 int powerctrl_set_sysclk(uint32_t sysclk, uint32_t ahb, uint32_t apb1, uint32_t apb2) {
-    // For now it's not supported to change SYSCLK (only bus dividers).
-    if (sysclk != HAL_RCC_GetSysClockFreq()) {
-        return -MP_EINVAL;
+    int sysclk_mode = SYSCLK_MODE_NONE;
+    uint32_t msirange = 0;
+    uint32_t sysclk_cur = HAL_RCC_GetSysClockFreq();
+
+    if (sysclk == sysclk_cur) {
+        // SYSCLK does not need changing.
+    } else if (sysclk == 64000000) {
+        sysclk_mode = SYSCLK_MODE_HSE_64M;
+    } else {
+        for (msirange = 0; msirange < MP_ARRAY_SIZE(MSIRangeTable); ++msirange) {
+            if (MSIRangeTable[msirange] != 0 && sysclk == MSIRangeTable[msirange]) {
+                sysclk_mode = SYSCLK_MODE_MSI;
+                break;
+            }
+        }
+
+        if (sysclk_mode == SYSCLK_MODE_NONE) {
+            // Unsupported SYSCLK value.
+            return -MP_EINVAL;
+        }
+    }
+
+    // Exit LPR if SYSCLK will increase beyond threshold.
+    if (LL_PWR_IsEnabledLowPowerRunMode()) {
+        if (sysclk > LPR_THRESHOLD) {
+            if (sysclk_cur < LPR_THRESHOLD) {
+                // Must select MSI=LPR_THRESHOLD=2MHz to exit LPR.
+                LL_RCC_MSI_SetRange(LL_RCC_MSIRANGE_5);
+            }
+
+            // Exit LPR and wait for the regulator to be ready.
+            LL_PWR_ExitLowPowerRunMode();
+            while (!LL_PWR_IsActiveFlag_REGLPF()) {
+            }
+        }
+    }
+
+    // Select VOS1 if SYSCLK will increase beyond threshold.
+    if (sysclk > VOS2_THRESHOLD) {
+        LL_PWR_SetRegulVoltageScaling(LL_PWR_REGU_VOLTAGE_SCALE1);
+        while (LL_PWR_IsActiveFlag_VOS()) {
+        }
+    }
+
+    if (sysclk_mode == SYSCLK_MODE_HSE_64M) {
+        SystemClock_Config();
+    } else if (sysclk_mode == SYSCLK_MODE_MSI) {
+        // Set flash latency to maximum to ensure the latency is large enough for
+        // both the current SYSCLK and the SYSCLK that will be selected below.
+        LL_FLASH_SetLatency(LL_FLASH_LATENCY_3);
+        while (LL_FLASH_GetLatency() != LL_FLASH_LATENCY_3) {
+        }
+
+        // Before changing the MSIRANGE value, if MSI is on then it must also be ready.
+        while ((RCC->CR & (RCC_CR_MSIRDY | RCC_CR_MSION)) == RCC_CR_MSION) {
+        }
+        LL_RCC_MSI_SetRange(msirange << RCC_CR_MSIRANGE_Pos);
+
+        // Clock SYSCLK from MSI.
+        LL_RCC_SetSysClkSource(LL_RCC_SYS_CLKSOURCE_MSI);
+        while (LL_RCC_GetSysClkSource() != LL_RCC_SYS_CLKSOURCE_STATUS_MSI) {
+        }
+
+        // Disable PLL to decrease power consumption.
+        LL_RCC_PLL_Disable();
+        while (LL_RCC_PLL_IsReady() != 0) {
+        }
+        LL_RCC_PLL_DisableDomain_SYS();
+
+        // Select VOS2 if possible.
+        if (sysclk <= VOS2_THRESHOLD) {
+            LL_PWR_SetRegulVoltageScaling(LL_PWR_REGU_VOLTAGE_SCALE2);
+        }
+
+        // Enter LPR if possible.
+        if (sysclk <= LPR_THRESHOLD) {
+            LL_PWR_EnterLowPowerRunMode();
+        }
+
+        // Configure flash latency for the new SYSCLK.
+        LL_SetFlashLatency(sysclk);
+
+        // Update HAL state and SysTick.
+        SystemCoreClockUpdate();
+        powerctrl_config_systick();
     }
 
     // Return straightaway if the clocks are already at the desired frequency.
diff --git a/ports/stm32/powerctrl.h b/ports/stm32/powerctrl.h
index 9f223e794..eedc448b2 100644
--- a/ports/stm32/powerctrl.h
+++ b/ports/stm32/powerctrl.h
@@ -35,6 +35,7 @@ NORETURN void powerctrl_mcu_reset(void);
 NORETURN void powerctrl_enter_bootloader(uint32_t r0, uint32_t bl_addr);
 void powerctrl_check_enter_bootloader(void);
 
+void powerctrl_config_systick(void);
 int powerctrl_rcc_clock_config_pll(RCC_ClkInitTypeDef *rcc_init, uint32_t sysclk_mhz, bool need_pllsai);
 int powerctrl_set_sysclk(uint32_t sysclk, uint32_t ahb, uint32_t apb1, uint32_t apb2);
 void powerctrl_enter_stop_mode(void);
diff --git a/ports/stm32/powerctrlboot.c b/ports/stm32/powerctrlboot.c
index 880e43e04..caa563292 100644
--- a/ports/stm32/powerctrlboot.c
+++ b/ports/stm32/powerctrlboot.c
@@ -28,7 +28,7 @@
 #include "irq.h"
 #include "powerctrl.h"
 
-static inline void powerctrl_config_systick(void) {
+void powerctrl_config_systick(void) {
     // Configure SYSTICK to run at 1kHz (1ms interval)
     SysTick->CTRL |= SYSTICK_CLKSOURCE_HCLK;
     SysTick_Config(HAL_RCC_GetHCLKFreq() / 1000);
diff --git a/ports/stm32/pyb_i2c.c b/ports/stm32/pyb_i2c.c
index f0bd38333..dbcf4bcb8 100644
--- a/ports/stm32/pyb_i2c.c
+++ b/ports/stm32/pyb_i2c.c
@@ -49,14 +49,14 @@
 ///     from pyb import I2C
 ///
 ///     i2c = I2C(1)                         # create on bus 1
-///     i2c = I2C(1, I2C.MASTER)             # create and init as a master
-///     i2c.init(I2C.MASTER, baudrate=20000) # init as a master
-///     i2c.init(I2C.SLAVE, addr=0x42)       # init as a slave with given address
-///     i2c.deinit()                         # turn off the peripheral
+///     i2c = I2C(1, I2C.CONTROLLER)         # create and init as a controller
+///     i2c.init(I2C.CONTROLLER, baudrate=20000) # init as a controller
+///     i2c.init(I2C.PERIPHERAL, addr=0x42)  # init as a peripheral with given address
+///     i2c.deinit()                         # turn off the I2C unit
 ///
 /// Printing the i2c object gives you information about its configuration.
 ///
-/// Basic methods for slave are send and recv:
+/// Basic methods for peripheral are send and recv:
 ///
 ///     i2c.send('abc')      # send 3 bytes
 ///     i2c.send(0x42)       # send a single byte, given by the number
@@ -71,19 +71,19 @@
 ///
 ///     i2c.send(b'123', timeout=2000)   # timout after 2 seconds
 ///
-/// A master must specify the recipient's address:
+/// A controller must specify the recipient's address:
 ///
-///     i2c.init(I2C.MASTER)
-///     i2c.send('123', 0x42)        # send 3 bytes to slave with address 0x42
+///     i2c.init(I2C.CONTROLLER)
+///     i2c.send('123', 0x42)        # send 3 bytes to peripheral with address 0x42
 ///     i2c.send(b'456', addr=0x42)  # keyword for address
 ///
 /// Master also has other methods:
 ///
-///     i2c.is_ready(0x42)           # check if slave 0x42 is ready
-///     i2c.scan()                   # scan for slaves on the bus, returning
+///     i2c.is_ready(0x42)           # check if peripheral 0x42 is ready
+///     i2c.scan()                   # scan for peripherals on the bus, returning
 ///                                  #   a list of valid addresses
-///     i2c.mem_read(3, 0x42, 2)     # read 3 bytes from memory of slave 0x42,
-///                                  #   starting at address 2 in the slave
+///     i2c.mem_read(3, 0x42, 2)     # read 3 bytes from memory of peripheral 0x42,
+///                                  #   starting at address 2 in the peripheral
 ///     i2c.mem_write('abc', 0x42, 2, timeout=1000)
 #define PYB_I2C_MASTER (0)
 #define PYB_I2C_SLAVE  (1)
@@ -578,7 +578,7 @@ STATIC void pyb_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_ki
         mp_printf(print, "I2C(%u)", i2c_num);
     } else {
         if (in_master_mode(self)) {
-            mp_printf(print, "I2C(%u, I2C.MASTER, baudrate=%u"
+            mp_printf(print, "I2C(%u, I2C.CONTROLLER, baudrate=%u"
                 #if PYB_I2C_TIMINGR
                 ", timingr=0x%08x"
                 #endif
@@ -588,7 +588,7 @@ STATIC void pyb_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_ki
                 #endif
                 );
         } else {
-            mp_printf(print, "I2C(%u, I2C.SLAVE, addr=0x%02x)", i2c_num, (self->i2c->Instance->OAR1 >> 1) & 0x7f);
+            mp_printf(print, "I2C(%u, I2C.PERIPHERAL, addr=0x%02x)", i2c_num, (self->i2c->Instance->OAR1 >> 1) & 0x7f);
         }
     }
 }
@@ -597,9 +597,9 @@ STATIC void pyb_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_ki
 ///
 /// Initialise the I2C bus with the given parameters:
 ///
-///   - `mode` must be either `I2C.MASTER` or `I2C.SLAVE`
-///   - `addr` is the 7-bit address (only sensible for a slave)
-///   - `baudrate` is the SCL clock rate (only sensible for a master)
+///   - `mode` must be either `I2C.CONTROLLER` or `I2C.PERIPHERAL`
+///   - `addr` is the 7-bit address (only sensible for a peripheral)
+///   - `baudrate` is the SCL clock rate (only sensible for a controller)
 ///   - `gencall` is whether to support general call mode
 STATIC mp_obj_t pyb_i2c_init_helper(const pyb_i2c_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     static const mp_arg_t allowed_args[] = {
@@ -621,7 +621,7 @@ STATIC mp_obj_t pyb_i2c_init_helper(const pyb_i2c_obj_t *self, size_t n_args, co
     I2C_InitTypeDef *init = &self->i2c->Init;
 
     if (args[0].u_int == PYB_I2C_MASTER) {
-        // use a special address to indicate we are a master
+        // use a special address to indicate we are a controller
         init->OwnAddress1 = PYB_I2C_MASTER_ADDRESS;
     } else {
         init->OwnAddress1 = (args[1].u_int << 1) & 0xfe;
@@ -697,12 +697,12 @@ STATIC mp_obj_t pyb_i2c_deinit(mp_obj_t self_in) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_i2c_deinit_obj, pyb_i2c_deinit);
 
 /// \method is_ready(addr)
-/// Check if an I2C device responds to the given address.  Only valid when in master mode.
+/// Check if an I2C device responds to the given address.  Only valid when in controller mode.
 STATIC mp_obj_t pyb_i2c_is_ready(mp_obj_t self_in, mp_obj_t i2c_addr_o) {
     pyb_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
 
     if (!in_master_mode(self)) {
-        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a master"));
+        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a controller"));
     }
 
     mp_uint_t i2c_addr = mp_obj_get_int(i2c_addr_o) << 1;
@@ -720,12 +720,12 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_i2c_is_ready_obj, pyb_i2c_is_ready);
 
 /// \method scan()
 /// Scan all I2C addresses from 0x08 to 0x77 and return a list of those that respond.
-/// Only valid when in master mode.
+/// Only valid when in controller mode.
 STATIC mp_obj_t pyb_i2c_scan(mp_obj_t self_in) {
     pyb_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
 
     if (!in_master_mode(self)) {
-        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a master"));
+        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a controller"));
     }
 
     mp_obj_t list = mp_obj_new_list(0, NULL);
@@ -745,7 +745,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_i2c_scan_obj, pyb_i2c_scan);
 /// Send data on the bus:
 ///
 ///   - `send` is the data to send (an integer to send, or a buffer object)
-///   - `addr` is the address to send to (only required in master mode)
+///   - `addr` is the address to send to (only required in controller mode)
 ///   - `timeout` is the timeout in milliseconds to wait for the send
 ///
 /// Return value: `None`.
@@ -824,7 +824,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_send_obj, 1, pyb_i2c_send);
 ///
 ///   - `recv` can be an integer, which is the number of bytes to receive,
 ///     or a mutable buffer, which will be filled with received bytes
-///   - `addr` is the address to receive from (only required in master mode)
+///   - `addr` is the address to receive from (only required in controller mode)
 ///   - `timeout` is the timeout in milliseconds to wait for the receive
 ///
 /// Return value: if `recv` is an integer then a new buffer of the bytes received,
@@ -910,7 +910,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_recv_obj, 1, pyb_i2c_recv);
 ///   - `addr_size` selects width of memaddr: 8 or 16 bits
 ///
 /// Returns the read data.
-/// This is only valid in master mode.
+/// This is only valid in controller mode.
 STATIC const mp_arg_t pyb_i2c_mem_read_allowed_args[] = {
     { MP_QSTR_data,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
     { MP_QSTR_addr,    MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
@@ -926,7 +926,7 @@ STATIC mp_obj_t pyb_i2c_mem_read(size_t n_args, const mp_obj_t *pos_args, mp_map
     mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(pyb_i2c_mem_read_allowed_args), pyb_i2c_mem_read_allowed_args, args);
 
     if (!in_master_mode(self)) {
-        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a master"));
+        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a controller"));
     }
 
     // get the buffer to read into
@@ -986,7 +986,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_mem_read_obj, 1, pyb_i2c_mem_read);
 ///   - `addr_size` selects width of memaddr: 8 or 16 bits
 ///
 /// Returns `None`.
-/// This is only valid in master mode.
+/// This is only valid in controller mode.
 STATIC mp_obj_t pyb_i2c_mem_write(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     // parse args (same as mem_read)
     pyb_i2c_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
@@ -994,7 +994,7 @@ STATIC mp_obj_t pyb_i2c_mem_write(size_t n_args, const mp_obj_t *pos_args, mp_ma
     mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(pyb_i2c_mem_read_allowed_args), pyb_i2c_mem_read_allowed_args, args);
 
     if (!in_master_mode(self)) {
-        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a master"));
+        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a controller"));
     }
 
     // get the buffer to write from
@@ -1051,8 +1051,11 @@ STATIC const mp_rom_map_elem_t pyb_i2c_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_mem_write), MP_ROM_PTR(&pyb_i2c_mem_write_obj) },
 
     // class constants
-    /// \constant MASTER - for initialising the bus to master mode
-    /// \constant SLAVE - for initialising the bus to slave mode
+    /// \constant CONTROLLER - for initialising the bus to controller mode
+    /// \constant PERIPHERAL - for initialising the bus to peripheral mode
+    { MP_ROM_QSTR(MP_QSTR_CONTROLLER), MP_ROM_INT(PYB_I2C_MASTER) },
+    { MP_ROM_QSTR(MP_QSTR_PERIPHERAL),  MP_ROM_INT(PYB_I2C_SLAVE) },
+    // TODO - remove MASTER/SLAVE when CONTROLLER/PERIPHERAL gain wide adoption
     { MP_ROM_QSTR(MP_QSTR_MASTER), MP_ROM_INT(PYB_I2C_MASTER) },
     { MP_ROM_QSTR(MP_QSTR_SLAVE), MP_ROM_INT(PYB_I2C_SLAVE) },
 };
diff --git a/ports/stm32/pyb_spi.c b/ports/stm32/pyb_spi.c
index 99a1cd77b..abb7ba41d 100644
--- a/ports/stm32/pyb_spi.c
+++ b/ports/stm32/pyb_spi.c
@@ -32,18 +32,18 @@
 /******************************************************************************/
 // MicroPython bindings for legacy pyb API
 
-// class pyb.SPI - a master-driven serial protocol
+// class pyb.SPI - a controller-driven serial protocol
 //
-// SPI is a serial protocol that is driven by a master.  At the physical level
+// SPI is a serial protocol that is driven by a controller.  At the physical level
 // there are 3 lines: SCK, MOSI, MISO.
 //
 // See usage model of I2C; SPI is very similar.  Main difference is
 // parameters to init the SPI bus:
 //
 //     from pyb import SPI
-//     spi = SPI(1, SPI.MASTER, baudrate=600000, polarity=1, phase=0, crc=0x7)
+//     spi = SPI(1, SPI.CONTROLLER, baudrate=600000, polarity=1, phase=0, crc=0x7)
 //
-// Only required parameter is mode, SPI.MASTER or SPI.SLAVE.  Polarity can be
+// Only required parameter is mode, SPI.CONTROLLER or SPI.PERIPHERAL.  Polarity can be
 // 0 or 1, and is the level the idle clock line sits at.  Phase can be 0 or 1
 // to sample data on the first or second clock edge respectively.  Crc can be
 // None for no CRC, or a polynomial specifier.
@@ -72,8 +72,8 @@ STATIC void pyb_spi_print(const mp_print_t *print, mp_obj_t self_in, mp_print_ki
 // init(mode, baudrate=328125, *, polarity=1, phase=0, bits=8, firstbit=SPI.MSB, ti=False, crc=None)
 //
 // Initialise the SPI bus with the given parameters:
-//   - `mode` must be either `SPI.MASTER` or `SPI.SLAVE`.
-//   - `baudrate` is the SCK clock rate (only sensible for a master).
+//   - `mode` must be either `SPI.CONTROLLER` or `SPI.PERIPHERAL`.
+//   - `baudrate` is the SCK clock rate (only sensible for a controller).
 STATIC mp_obj_t pyb_spi_init_helper(const pyb_spi_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_mode,     MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
@@ -319,10 +319,13 @@ STATIC const mp_rom_map_elem_t pyb_spi_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_send_recv), MP_ROM_PTR(&pyb_spi_send_recv_obj) },
 
     // class constants
-    /// \constant MASTER - for initialising the bus to master mode
-    /// \constant SLAVE - for initialising the bus to slave mode
+    /// \constant CONTROLLER - for initialising the bus to controller mode
+    /// \constant PERIPHERAL - for initialising the bus to peripheral mode
     /// \constant MSB - set the first bit to MSB
     /// \constant LSB - set the first bit to LSB
+    { MP_ROM_QSTR(MP_QSTR_CONTROLLER), MP_ROM_INT(SPI_MODE_MASTER) },
+    { MP_ROM_QSTR(MP_QSTR_PERIPHERAL),  MP_ROM_INT(SPI_MODE_SLAVE) },
+    // TODO - remove MASTER/SLAVE when CONTROLLER/PERIPHERAL gain wide adoption
     { MP_ROM_QSTR(MP_QSTR_MASTER), MP_ROM_INT(SPI_MODE_MASTER) },
     { MP_ROM_QSTR(MP_QSTR_SLAVE),  MP_ROM_INT(SPI_MODE_SLAVE) },
     { MP_ROM_QSTR(MP_QSTR_MSB),    MP_ROM_INT(SPI_FIRSTBIT_MSB) },
diff --git a/ports/stm32/rtc.c b/ports/stm32/rtc.c
index 02b0f2dbd..ab8b49e18 100644
--- a/ports/stm32/rtc.c
+++ b/ports/stm32/rtc.c
@@ -27,7 +27,7 @@
 #include <stdio.h>
 
 #include "py/runtime.h"
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 #include "extint.h"
 #include "rtc.h"
 #include "irq.h"
diff --git a/ports/stm32/sdram.c b/ports/stm32/sdram.c
index 514192519..e0e350083 100644
--- a/ports/stm32/sdram.c
+++ b/ports/stm32/sdram.c
@@ -283,52 +283,106 @@ void sdram_leave_low_power(void) {
 #pragma GCC diagnostic ignored "-Wstringop-overflow"
 #endif
 
-bool sdram_test(bool fast) {
+bool __attribute__((optimize("O0"))) sdram_test(bool exhaustive) {
     uint8_t const pattern = 0xaa;
     uint8_t const antipattern = 0x55;
     uint8_t *const mem_base = (uint8_t *)sdram_start();
 
-    /* test data bus */
-    for (uint8_t i = 1; i; i <<= 1) {
-        *mem_base = i;
-        if (*mem_base != i) {
-            printf("data bus lines test failed! data (%d)\n", i);
+    #if MICROPY_HW_SDRAM_TEST_FAIL_ON_ERROR
+    char error_buffer[1024];
+    #endif
+
+    #if (__DCACHE_PRESENT == 1)
+    bool i_cache_disabled = false;
+    bool d_cache_disabled = false;
+
+    // Disable caches for testing.
+    if (SCB->CCR & (uint32_t)SCB_CCR_IC_Msk) {
+        SCB_DisableICache();
+        i_cache_disabled = true;
+    }
+
+    if (SCB->CCR & (uint32_t)SCB_CCR_DC_Msk) {
+        SCB_DisableDCache();
+        d_cache_disabled = true;
+    }
+    #endif
+
+    // Test data bus
+    for (uint32_t i = 0; i < MICROPY_HW_SDRAM_MEM_BUS_WIDTH; i++) {
+        *((uint32_t *)mem_base) = (1 << i);
+        if (*((uint32_t *)mem_base) != (1 << i)) {
+            #if MICROPY_HW_SDRAM_TEST_FAIL_ON_ERROR
+            snprintf(error_buffer, sizeof(error_buffer),
+                "Data bus test failed at 0x%p expected 0x%x found 0x%lx",
+                &mem_base[0], (1 << i), ((uint32_t *)mem_base)[0]);
+            __fatal_error(error_buffer);
+            #endif
             return false;
         }
     }
 
-    /* test address bus */
-    /* Check individual address lines */
+    // Test address bus
     for (uint32_t i = 1; i < MICROPY_HW_SDRAM_SIZE; i <<= 1) {
         mem_base[i] = pattern;
         if (mem_base[i] != pattern) {
-            printf("address bus lines test failed! address (%p)\n", &mem_base[i]);
+            #if MICROPY_HW_SDRAM_TEST_FAIL_ON_ERROR
+            snprintf(error_buffer, sizeof(error_buffer),
+                "Address bus test failed at 0x%p expected 0x%x found 0x%x",
+                &mem_base[i], pattern, mem_base[i]);
+            __fatal_error(error_buffer);
+            #endif
             return false;
         }
     }
 
-    /* Check for aliasing (overlaping addresses) */
+    // Check for aliasing (overlaping addresses)
     mem_base[0] = antipattern;
     for (uint32_t i = 1; i < MICROPY_HW_SDRAM_SIZE; i <<= 1) {
         if (mem_base[i] != pattern) {
-            printf("address bus overlap %p\n", &mem_base[i]);
+            #if MICROPY_HW_SDRAM_TEST_FAIL_ON_ERROR
+            snprintf(error_buffer, sizeof(error_buffer),
+                "Address bus overlap at 0x%p expected 0x%x found 0x%x",
+                &mem_base[i], pattern, mem_base[i]);
+            __fatal_error(error_buffer);
+            #endif
             return false;
         }
     }
 
-    /* test all ram cells */
-    if (!fast) {
-        for (uint32_t i = 0; i < MICROPY_HW_SDRAM_SIZE; ++i) {
+    // Test all RAM cells
+    if (exhaustive) {
+        // Write all memory first then compare, so even if the cache
+        // is enabled, it's not just writing and reading from cache.
+        // Note: This test should also detect refresh rate issues.
+        for (uint32_t i = 0; i < MICROPY_HW_SDRAM_SIZE; i++) {
             mem_base[i] = pattern;
+        }
+
+        for (uint32_t i = 0; i < MICROPY_HW_SDRAM_SIZE; i++) {
             if (mem_base[i] != pattern) {
-                printf("address bus test failed! address (%p)\n", &mem_base[i]);
+                #if MICROPY_HW_SDRAM_TEST_FAIL_ON_ERROR
+                snprintf(error_buffer, sizeof(error_buffer),
+                    "Address bus slow test failed at 0x%p expected 0x%x found 0x%x",
+                    &mem_base[i], pattern, mem_base[i]);
+                __fatal_error(error_buffer);
+                #endif
                 return false;
             }
         }
-    } else {
-        memset(mem_base, pattern, MICROPY_HW_SDRAM_SIZE);
     }
 
+    #if (__DCACHE_PRESENT == 1)
+    // Re-enable caches if they were enabled before the test started.
+    if (i_cache_disabled) {
+        SCB_EnableICache();
+    }
+
+    if (d_cache_disabled) {
+        SCB_EnableDCache();
+    }
+    #endif
+
     return true;
 }
 
diff --git a/ports/stm32/sdram.h b/ports/stm32/sdram.h
index 773a30802..f7a124add 100644
--- a/ports/stm32/sdram.h
+++ b/ports/stm32/sdram.h
@@ -13,5 +13,5 @@ void *sdram_start(void);
 void *sdram_end(void);
 void sdram_enter_low_power(void);
 void sdram_leave_low_power(void);
-bool sdram_test(bool fast);
+bool sdram_test(bool exhaustive);
 #endif // __SDRAM_H__
diff --git a/ports/stm32/spi.c b/ports/stm32/spi.c
index d3b3a784e..0ce6b5abc 100644
--- a/ports/stm32/spi.c
+++ b/ports/stm32/spi.c
@@ -640,14 +640,14 @@ void spi_print(const mp_print_t *print, const spi_t *spi_obj, bool legacy) {
             #endif
             uint baudrate = spi_get_source_freq(spi) >> log_prescaler;
             if (legacy) {
-                mp_printf(print, ", SPI.MASTER");
+                mp_printf(print, ", SPI.CONTROLLER");
             }
             mp_printf(print, ", baudrate=%u", baudrate);
             if (legacy) {
                 mp_printf(print, ", prescaler=%u", 1 << log_prescaler);
             }
         } else {
-            mp_printf(print, ", SPI.SLAVE");
+            mp_printf(print, ", SPI.PERIPHERAL");
         }
         mp_printf(print, ", polarity=%u, phase=%u, bits=%u", spi->Init.CLKPolarity == SPI_POLARITY_LOW ? 0 : 1, spi->Init.CLKPhase == SPI_PHASE_1EDGE ? 0 : 1, spi->Init.DataSize == SPI_DATASIZE_8BIT ? 8 : 16);
         if (spi->Init.CRCCalculation == SPI_CRCCALCULATION_ENABLE) {
diff --git a/ports/stm32/spibdev.c b/ports/stm32/spibdev.c
index 5090b43b1..afa6f4ecd 100644
--- a/ports/stm32/spibdev.c
+++ b/ports/stm32/spibdev.c
@@ -59,13 +59,6 @@ int32_t spi_bdev_ioctl(spi_bdev_t *bdev, uint32_t op, uint32_t arg) {
             }
             #endif
             return 0;
-
-        case BDEV_IOCTL_BLOCK_ERASE: {
-            uint32_t basepri = raise_irq_pri(IRQ_PRI_FLASH); // prevent cache flushing and USB access
-            mp_spiflash_erase_block(&bdev->spiflash, arg * MP_SPIFLASH_ERASE_BLOCK_SIZE);
-            restore_irq_pri(basepri);
-            return 0;
-        }
     }
     return -MP_EINVAL;
 }
@@ -108,4 +101,19 @@ int spi_bdev_writeblocks_raw(spi_bdev_t *bdev, const uint8_t *src, uint32_t bloc
     return ret;
 }
 
+int spi_bdev_eraseblocks_raw(spi_bdev_t *bdev, uint32_t block_num, uint32_t num_bytes) {
+    int ret = 0;
+    while (num_bytes >= MP_SPIFLASH_ERASE_BLOCK_SIZE) {
+        uint32_t basepri = raise_irq_pri(IRQ_PRI_FLASH); // prevent cache flushing and USB access
+        ret = mp_spiflash_erase_block(&bdev->spiflash, block_num * MP_SPIFLASH_ERASE_BLOCK_SIZE);
+        restore_irq_pri(basepri);
+        if (ret) {
+            break;
+        }
+        block_num += 1;
+        num_bytes -= MP_SPIFLASH_ERASE_BLOCK_SIZE;
+    }
+    return ret;
+}
+
 #endif
diff --git a/ports/stm32/stm32_it.c b/ports/stm32/stm32_it.c
index 3533419d9..fcd5b034a 100644
--- a/ports/stm32/stm32_it.c
+++ b/ports/stm32/stm32_it.c
@@ -625,7 +625,7 @@ void TIM1_TRG_COM_TIM11_IRQHandler(void) {
     IRQ_EXIT(TIM1_TRG_COM_TIM11_IRQn);
 }
 
-#if defined(STM32L4)
+#if defined(STM32L4) || defined(STM32WB)
 void TIM1_TRG_COM_TIM17_IRQHandler(void) {
     IRQ_ENTER(TIM1_TRG_COM_TIM17_IRQn);
     timer_irq_handler(17);
diff --git a/ports/stm32/storage.c b/ports/stm32/storage.c
index a71c4a3ea..fcc6d51b3 100644
--- a/ports/stm32/storage.c
+++ b/ports/stm32/storage.c
@@ -234,24 +234,27 @@ int storage_write_blocks(const uint8_t *src, uint32_t block_num, uint32_t num_bl
 
 #ifdef MICROPY_HW_BDEV_SPIFLASH_EXTENDED
 // Board defined an external SPI flash for use with extended block protocol
-#define SPIFLASH (MICROPY_HW_BDEV_SPIFLASH_EXTENDED)
-#define PYB_FLASH_NATIVE_BLOCK_SIZE (MP_SPIFLASH_ERASE_BLOCK_SIZE)
-#define MICROPY_HW_BDEV_READBLOCKS_EXT(dest, bl, off, len) (spi_bdev_readblocks_raw(SPIFLASH, (dest), (bl), (off), (len)))
-#define MICROPY_HW_BDEV_WRITEBLOCKS_EXT(dest, bl, off, len) (spi_bdev_writeblocks_raw(SPIFLASH, (dest), (bl), (off), (len)))
+#define MICROPY_HW_BDEV_BLOCKSIZE_EXT (MP_SPIFLASH_ERASE_BLOCK_SIZE)
+#define MICROPY_HW_BDEV_READBLOCKS_EXT(dest, bl, off, len) \
+    (spi_bdev_readblocks_raw(MICROPY_HW_BDEV_SPIFLASH_EXTENDED, (dest), (bl), (off), (len)))
+#define MICROPY_HW_BDEV_WRITEBLOCKS_EXT(src, bl, off, len) \
+    (spi_bdev_writeblocks_raw(MICROPY_HW_BDEV_SPIFLASH_EXTENDED, (src), (bl), (off), (len)))
+#define MICROPY_HW_BDEV_ERASEBLOCKS_EXT(bl, len) \
+    (spi_bdev_eraseblocks_raw(MICROPY_HW_BDEV_SPIFLASH_EXTENDED, (bl), (len)))
 
 #elif (MICROPY_VFS_LFS1 || MICROPY_VFS_LFS2) && MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
 // Board uses littlefs and internal flash, so enable extended block protocol on internal flash
-#define PYB_FLASH_NATIVE_BLOCK_SIZE (FLASH_BLOCK_SIZE)
+#define MICROPY_HW_BDEV_BLOCKSIZE_EXT (FLASH_BLOCK_SIZE)
 #define MICROPY_HW_BDEV_READBLOCKS_EXT(dest, bl, off, len) (flash_bdev_readblocks_ext((dest), (bl), (off), (len)))
 #define MICROPY_HW_BDEV_WRITEBLOCKS_EXT(dest, bl, off, len) (flash_bdev_writeblocks_ext((dest), (bl), (off), (len)))
 #endif
 
-#ifndef PYB_FLASH_NATIVE_BLOCK_SIZE
-#define PYB_FLASH_NATIVE_BLOCK_SIZE (FLASH_BLOCK_SIZE)
+#ifndef MICROPY_HW_BDEV_BLOCKSIZE_EXT
+#define MICROPY_HW_BDEV_BLOCKSIZE_EXT (FLASH_BLOCK_SIZE)
 #endif
 
 #if defined(MICROPY_HW_BDEV_READBLOCKS_EXT)
-// Size of blocks is PYB_FLASH_NATIVE_BLOCK_SIZE
+// Size of blocks is MICROPY_HW_BDEV_BLOCKSIZE_EXT
 int storage_readblocks_ext(uint8_t *dest, uint32_t block, uint32_t offset, uint32_t len) {
     return MICROPY_HW_BDEV_READBLOCKS_EXT(dest, block, offset, len);
 }
@@ -261,9 +264,7 @@ typedef struct _pyb_flash_obj_t {
     mp_obj_base_t base;
     uint32_t start; // in bytes
     uint32_t len; // in bytes
-    #if defined(SPIFLASH)
     bool use_native_block_size;
-    #endif
 } pyb_flash_obj_t;
 
 // This Flash object represents the entire available flash, with emulated partition table at start
@@ -299,23 +300,21 @@ STATIC mp_obj_t pyb_flash_make_new(const mp_obj_type_t *type, size_t n_args, siz
 
     pyb_flash_obj_t *self = m_new_obj(pyb_flash_obj_t);
     self->base.type = &pyb_flash_type;
-    #if defined(SPIFLASH)
     self->use_native_block_size = false;
-    #endif
 
     uint32_t bl_len = (storage_get_block_count() - FLASH_PART1_START_BLOCK) * FLASH_BLOCK_SIZE;
 
     mp_int_t start = args[ARG_start].u_int;
     if (start == -1) {
         start = 0;
-    } else if (!(0 <= start && start < bl_len && start % PYB_FLASH_NATIVE_BLOCK_SIZE == 0)) {
+    } else if (!(0 <= start && start < bl_len && start % MICROPY_HW_BDEV_BLOCKSIZE_EXT == 0)) {
         mp_raise_ValueError(NULL);
     }
 
     mp_int_t len = args[ARG_len].u_int;
     if (len == -1) {
         len = bl_len - start;
-    } else if (!(0 < len && start + len <= bl_len && len % PYB_FLASH_NATIVE_BLOCK_SIZE == 0)) {
+    } else if (!(0 < len && start + len <= bl_len && len % MICROPY_HW_BDEV_BLOCKSIZE_EXT == 0)) {
         mp_raise_ValueError(NULL);
     }
 
@@ -340,10 +339,10 @@ STATIC mp_obj_t pyb_flash_readblocks(size_t n_args, const mp_obj_t *args) {
     else if (self != &pyb_flash_obj) {
         // Extended block read on a sub-section of the flash storage
         uint32_t offset = mp_obj_get_int(args[3]);
-        if ((block_num * PYB_FLASH_NATIVE_BLOCK_SIZE) >= self->len) {
+        if ((block_num * MICROPY_HW_BDEV_BLOCKSIZE_EXT) >= self->len) {
             ret = -MP_EFAULT; // Bad address
         } else {
-            block_num += self->start / PYB_FLASH_NATIVE_BLOCK_SIZE;
+            block_num += self->start / MICROPY_HW_BDEV_BLOCKSIZE_EXT;
             ret = MICROPY_HW_BDEV_READBLOCKS_EXT(bufinfo.buf, block_num, offset, bufinfo.len);
         }
     }
@@ -367,10 +366,10 @@ STATIC mp_obj_t pyb_flash_writeblocks(size_t n_args, const mp_obj_t *args) {
     else if (self != &pyb_flash_obj) {
         // Extended block write on a sub-section of the flash storage
         uint32_t offset = mp_obj_get_int(args[3]);
-        if ((block_num * PYB_FLASH_NATIVE_BLOCK_SIZE) >= self->len) {
+        if ((block_num * MICROPY_HW_BDEV_BLOCKSIZE_EXT) >= self->len) {
             ret = -MP_EFAULT; // Bad address
         } else {
-            block_num += self->start / PYB_FLASH_NATIVE_BLOCK_SIZE;
+            block_num += self->start / MICROPY_HW_BDEV_BLOCKSIZE_EXT;
             ret = MICROPY_HW_BDEV_WRITEBLOCKS_EXT(bufinfo.buf, block_num, offset, bufinfo.len);
         }
     }
@@ -390,11 +389,9 @@ STATIC mp_obj_t pyb_flash_ioctl(mp_obj_t self_in, mp_obj_t cmd_in, mp_obj_t arg_
                 // Will be using extended block protocol
                 if (self == &pyb_flash_obj) {
                     ret = -1;
-                #if defined(SPIFLASH)
                 } else {
-                    // Switch to use native block size of SPI flash
+                    // Switch to use native block size of the underlying storage.
                     self->use_native_block_size = true;
-                #endif
                 }
             }
             return MP_OBJ_NEW_SMALL_INT(ret);
@@ -411,10 +408,8 @@ STATIC mp_obj_t pyb_flash_ioctl(mp_obj_t self_in, mp_obj_t cmd_in, mp_obj_t arg_
             if (self == &pyb_flash_obj) {
                 // Get true size
                 n = storage_get_block_count();
-            #if defined(SPIFLASH)
             } else if (self->use_native_block_size) {
-                n = self->len / PYB_FLASH_NATIVE_BLOCK_SIZE;
-            #endif
+                n = self->len / MICROPY_HW_BDEV_BLOCKSIZE_EXT;
             } else {
                 n = self->len / FLASH_BLOCK_SIZE;
             }
@@ -423,20 +418,19 @@ STATIC mp_obj_t pyb_flash_ioctl(mp_obj_t self_in, mp_obj_t cmd_in, mp_obj_t arg_
 
         case MP_BLOCKDEV_IOCTL_BLOCK_SIZE: {
             mp_int_t n = FLASH_BLOCK_SIZE;
-            #if defined(SPIFLASH)
             if (self->use_native_block_size) {
-                n = PYB_FLASH_NATIVE_BLOCK_SIZE;
+                n = MICROPY_HW_BDEV_BLOCKSIZE_EXT;
             }
-            #endif
             return MP_OBJ_NEW_SMALL_INT(n);
         }
 
         case MP_BLOCKDEV_IOCTL_BLOCK_ERASE: {
             int ret = 0;
-            #if defined(SPIFLASH)
+            #if defined(MICROPY_HW_BDEV_ERASEBLOCKS_EXT)
             if (self->use_native_block_size) {
-                mp_int_t block_num = self->start / PYB_FLASH_NATIVE_BLOCK_SIZE + mp_obj_get_int(arg_in);
-                ret = spi_bdev_ioctl(SPIFLASH, BDEV_IOCTL_BLOCK_ERASE, block_num);
+                mp_int_t block_num = self->start / MICROPY_HW_BDEV_BLOCKSIZE_EXT + mp_obj_get_int(arg_in);
+
+                ret = MICROPY_HW_BDEV_ERASEBLOCKS_EXT(block_num, MICROPY_HW_BDEV_BLOCKSIZE_EXT);
             }
             #endif
             return MP_OBJ_NEW_SMALL_INT(ret);
diff --git a/ports/stm32/storage.h b/ports/stm32/storage.h
index 73058aad6..05654855a 100644
--- a/ports/stm32/storage.h
+++ b/ports/stm32/storage.h
@@ -35,8 +35,7 @@
 enum {
     BDEV_IOCTL_INIT = 1,
     BDEV_IOCTL_SYNC = 3,
-    BDEV_IOCTL_NUM_BLOCKS = 4,
-    BDEV_IOCTL_BLOCK_ERASE = 6,
+    BDEV_IOCTL_NUM_BLOCKS = 4, // units are FLASH_BLOCK_SIZE
     BDEV_IOCTL_IRQ_HANDLER = 7,
 };
 
@@ -70,6 +69,7 @@ int spi_bdev_writeblocks(spi_bdev_t *bdev, const uint8_t *src, uint32_t block_nu
 // These raw functions bypass the cache and go directly to SPI flash
 int spi_bdev_readblocks_raw(spi_bdev_t *bdev, uint8_t *dest, uint32_t block_num, uint32_t block_offset, uint32_t num_bytes);
 int spi_bdev_writeblocks_raw(spi_bdev_t *bdev, const uint8_t *src, uint32_t block_num, uint32_t block_offset, uint32_t num_bytes);
+int spi_bdev_eraseblocks_raw(spi_bdev_t *bdev, uint32_t block_num, uint32_t num_bytes);
 
 extern const struct _mp_obj_type_t pyb_flash_type;
 extern const struct _pyb_flash_obj_t pyb_flash_obj;
diff --git a/ports/stm32/systick.c b/ports/stm32/systick.c
index d70fc0053..7d1e318ac 100644
--- a/ports/stm32/systick.c
+++ b/ports/stm32/systick.c
@@ -96,12 +96,12 @@ void mp_hal_delay_ms(mp_uint_t Delay) {
         // IRQs enabled, so can use systick counter to do the delay
         uint32_t start = uwTick;
         // Wraparound of tick is taken care of by 2's complement arithmetic.
-        while (uwTick - start < Delay) {
+        do {
             // This macro will execute the necessary idle behaviour.  It may
             // raise an exception, switch threads or enter sleep mode (waiting for
             // (at least) the SysTick interrupt).
             MICROPY_EVENT_POLL_HOOK
-        }
+        } while (uwTick - start < Delay);
     } else {
         // IRQs disabled, so need to use a busy loop for the delay.
         // To prevent possible overflow of the counter we use a double loop.
diff --git a/ports/stm32/uart.c b/ports/stm32/uart.c
index 9f7441617..d2953b264 100644
--- a/ports/stm32/uart.c
+++ b/ports/stm32/uart.c
@@ -32,8 +32,8 @@
 #include "py/stream.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"
-#include "lib/utils/interrupt_char.h"
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/interrupt_char.h"
+#include "shared/runtime/mpirq.h"
 #include "uart.h"
 #include "irq.h"
 #include "pendsv.h"
@@ -488,7 +488,7 @@ bool uart_init(pyb_uart_obj_t *uart_obj,
 
     uart_obj->uartx = UARTx;
 
-    // init UARTx
+    // Set the initialisation parameters for the UART.
     UART_HandleTypeDef huart;
     memset(&huart, 0, sizeof(huart));
     huart.Instance = UARTx;
@@ -499,6 +499,26 @@ bool uart_init(pyb_uart_obj_t *uart_obj,
     huart.Init.Mode = UART_MODE_TX_RX;
     huart.Init.HwFlowCtl = flow;
     huart.Init.OverSampling = UART_OVERSAMPLING_16;
+    #if !defined(STM32F4)
+    huart.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
+    #endif
+
+    #if defined(STM32H7) || defined(STM32WB)
+    // Compute the smallest prescaler that will allow the given baudrate.
+    uint32_t presc = UART_PRESCALER_DIV1;
+    if (uart_obj->uart_id == PYB_LPUART_1) {
+        uint32_t source_clk = uart_get_source_freq(uart_obj);
+        for (; presc < UART_PRESCALER_DIV256; ++presc) {
+            uint32_t brr = UART_DIV_LPUART(source_clk, baudrate, presc);
+            if (brr <= LPUART_BRR_MASK) {
+                break;
+            }
+        }
+    }
+    huart.Init.ClockPrescaler = presc;
+    #endif
+
+    // Initialise the UART hardware.
     HAL_UART_Init(&huart);
 
     // Disable all individual UART IRQs, but enable the global handler
@@ -746,6 +766,15 @@ uint32_t uart_get_source_freq(pyb_uart_obj_t *self) {
 }
 
 uint32_t uart_get_baudrate(pyb_uart_obj_t *self) {
+    #if defined(LPUART1)
+    if (self->uart_id == PYB_LPUART_1) {
+        return LL_LPUART_GetBaudRate(self->uartx, uart_get_source_freq(self)
+            #if defined(STM32H7) || defined(STM32WB)
+            , self->uartx->PRESC
+            #endif
+            );
+    }
+    #endif
     return LL_USART_GetBaudRate(self->uartx, uart_get_source_freq(self),
         #if defined(STM32H7) || defined(STM32WB)
         self->uartx->PRESC,
@@ -754,6 +783,16 @@ uint32_t uart_get_baudrate(pyb_uart_obj_t *self) {
 }
 
 void uart_set_baudrate(pyb_uart_obj_t *self, uint32_t baudrate) {
+    #if defined(LPUART1)
+    if (self->uart_id == PYB_LPUART_1) {
+        LL_LPUART_SetBaudRate(self->uartx, uart_get_source_freq(self),
+            #if defined(STM32H7) || defined(STM32WB)
+            LL_LPUART_PRESCALER_DIV1,
+            #endif
+            baudrate);
+        return;
+    }
+    #endif
     LL_USART_SetBaudRate(self->uartx, uart_get_source_freq(self),
         #if defined(STM32H7) || defined(STM32WB)
         LL_USART_PRESCALER_DIV1,
diff --git a/ports/stm32/uart.h b/ports/stm32/uart.h
index 0490a617f..0a268ad46 100644
--- a/ports/stm32/uart.h
+++ b/ports/stm32/uart.h
@@ -26,7 +26,7 @@
 #ifndef MICROPY_INCLUDED_STM32_UART_H
 #define MICROPY_INCLUDED_STM32_UART_H
 
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/mpirq.h"
 
 typedef enum {
     PYB_UART_NONE = 0,
@@ -88,6 +88,7 @@ void uart_deinit(pyb_uart_obj_t *uart_obj);
 void uart_irq_handler(mp_uint_t uart_id);
 
 void uart_attach_to_repl(pyb_uart_obj_t *self, bool attached);
+uint32_t uart_get_source_freq(pyb_uart_obj_t *self);
 uint32_t uart_get_baudrate(pyb_uart_obj_t *self);
 void uart_set_baudrate(pyb_uart_obj_t *self, uint32_t baudrate);
 
diff --git a/ports/stm32/usb.c b/ports/stm32/usb.c
index 5e3802651..1ed45592e 100644
--- a/ports/stm32/usb.c
+++ b/ports/stm32/usb.c
@@ -39,7 +39,7 @@
 #include "py/stream.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/mpirq.h"
 #include "bufhelper.h"
 #include "storage.h"
 #include "sdcard.h"
@@ -412,7 +412,7 @@ STATIC mp_obj_t pyb_usb_mode(size_t n_args, const mp_obj_t *pos_args, mp_map_t *
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_mode, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
         { MP_QSTR_port, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
-        { MP_QSTR_vid, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = USBD_VID} },
+        { MP_QSTR_vid, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = MICROPY_HW_USB_VID} },
         { MP_QSTR_pid, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
         #if MICROPY_HW_USB_MSC
         { MP_QSTR_msc, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_PTR(&mp_const_empty_tuple_obj)} },
@@ -489,61 +489,61 @@ STATIC mp_obj_t pyb_usb_mode(size_t n_args, const mp_obj_t *pos_args, mp_map_t *
     uint8_t mode;
     if (strcmp(mode_str, "CDC+MSC") == 0 || strcmp(mode_str, "VCP+MSC") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_CDC_MSC;
+            pid = MICROPY_HW_USB_PID_CDC_MSC;
         }
         mode = USBD_MODE_CDC_MSC;
     } else if (strcmp(mode_str, "VCP+MSC+HID") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_CDC_MSC_HID;
+            pid = MICROPY_HW_USB_PID_CDC_MSC_HID;
         }
         mode = USBD_MODE_CDC_MSC_HID;
     #if MICROPY_HW_USB_CDC_NUM >= 2
     } else if (strcmp(mode_str, "VCP+VCP") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_CDC2;
+            pid = MICROPY_HW_USB_PID_CDC2;
         }
         mode = USBD_MODE_CDC2;
     } else if (strcmp(mode_str, "VCP+VCP+MSC") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_CDC2_MSC;
+            pid = MICROPY_HW_USB_PID_CDC2_MSC;
         }
         mode = USBD_MODE_CDC2_MSC;
     } else if (strcmp(mode_str, "2xVCP+MSC+HID") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_CDC2_MSC_HID;
+            pid = MICROPY_HW_USB_PID_CDC2_MSC_HID;
         }
         mode = USBD_MODE_CDC2_MSC_HID;
     #endif
     #if MICROPY_HW_USB_CDC_NUM >= 3
     } else if (strcmp(mode_str, "3xVCP") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_CDC3;
+            pid = MICROPY_HW_USB_PID_CDC3;
         }
         mode = USBD_MODE_CDC3;
     } else if (strcmp(mode_str, "3xVCP+MSC") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_CDC3_MSC;
+            pid = MICROPY_HW_USB_PID_CDC3_MSC;
         }
         mode = USBD_MODE_CDC3_MSC;
     } else if (strcmp(mode_str, "3xVCP+MSC+HID") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_CDC3_MSC_HID;
+            pid = MICROPY_HW_USB_PID_CDC3_MSC_HID;
         }
         mode = USBD_MODE_CDC3_MSC_HID;
     #endif
     } else if (strcmp(mode_str, "CDC+HID") == 0 || strcmp(mode_str, "VCP+HID") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_CDC_HID;
+            pid = MICROPY_HW_USB_PID_CDC_HID;
         }
         mode = USBD_MODE_CDC_HID;
     } else if (strcmp(mode_str, "CDC") == 0 || strcmp(mode_str, "VCP") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_CDC;
+            pid = MICROPY_HW_USB_PID_CDC;
         }
         mode = USBD_MODE_CDC;
     } else if (strcmp(mode_str, "MSC") == 0) {
         if (pid == -1) {
-            pid = USBD_PID_MSC;
+            pid = MICROPY_HW_USB_PID_MSC;
         }
         mode = USBD_MODE_MSC;
     } else {
diff --git a/ports/stm32/usb.h b/ports/stm32/usb.h
index 295038ebd..3c382887a 100644
--- a/ports/stm32/usb.h
+++ b/ports/stm32/usb.h
@@ -30,22 +30,6 @@
 
 #define PYB_USB_FLAG_USB_MODE_CALLED    (0x0002)
 
-#ifndef USBD_VID
-// Windows needs a different PID to distinguish different device configurations
-#define USBD_VID         (0xf055)
-#define USBD_PID_CDC_MSC (0x9800)
-#define USBD_PID_CDC_HID (0x9801)
-#define USBD_PID_CDC     (0x9802)
-#define USBD_PID_MSC     (0x9803)
-#define USBD_PID_CDC2_MSC (0x9804)
-#define USBD_PID_CDC2    (0x9805)
-#define USBD_PID_CDC3    (0x9806)
-#define USBD_PID_CDC3_MSC (0x9807)
-#define USBD_PID_CDC_MSC_HID (0x9808)
-#define USBD_PID_CDC2_MSC_HID (0x9809)
-#define USBD_PID_CDC3_MSC_HID (0x980a)
-#endif
-
 typedef enum {
     PYB_USB_STORAGE_MEDIUM_NONE = 0,
     PYB_USB_STORAGE_MEDIUM_FLASH,
diff --git a/ports/stm32/usbd_cdc_interface.c b/ports/stm32/usbd_cdc_interface.c
index a1ac5fd22..61a7c8248 100644
--- a/ports/stm32/usbd_cdc_interface.c
+++ b/ports/stm32/usbd_cdc_interface.c
@@ -42,7 +42,7 @@
 #include "pendsv.h"
 
 #include "py/obj.h"
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 #include "irq.h"
 
 #if MICROPY_HW_ENABLE_USB
@@ -172,7 +172,7 @@ int8_t usbd_cdc_control(usbd_cdc_state_t *cdc_in, uint8_t cmd, uint8_t *pbuf, ui
 }
 
 static inline uint16_t usbd_cdc_tx_buffer_mask(uint16_t val) {
-    return val & (USBD_CDC_TX_DATA_SIZE - 1);
+    return val & (MICROPY_HW_USB_CDC_TX_DATA_SIZE - 1);
 }
 
 static inline uint16_t usbd_cdc_tx_buffer_size(usbd_cdc_itf_t *cdc) {
@@ -188,18 +188,18 @@ static inline bool usbd_cdc_tx_buffer_will_be_empty(usbd_cdc_itf_t *cdc) {
 }
 
 static inline bool usbd_cdc_tx_buffer_full(usbd_cdc_itf_t *cdc) {
-    return usbd_cdc_tx_buffer_size(cdc) == USBD_CDC_TX_DATA_SIZE;
+    return usbd_cdc_tx_buffer_size(cdc) == MICROPY_HW_USB_CDC_TX_DATA_SIZE;
 }
 
 static uint16_t usbd_cdc_tx_send_length(usbd_cdc_itf_t *cdc) {
-    uint16_t to_end = USBD_CDC_TX_DATA_SIZE - usbd_cdc_tx_buffer_mask(cdc->tx_buf_ptr_out);
+    uint16_t to_end = MICROPY_HW_USB_CDC_TX_DATA_SIZE - usbd_cdc_tx_buffer_mask(cdc->tx_buf_ptr_out);
     return MIN(usbd_cdc_tx_buffer_size(cdc), to_end);
 }
 
 static void usbd_cdc_tx_buffer_put(usbd_cdc_itf_t *cdc, uint8_t data, bool check_overflow) {
     cdc->tx_buf[usbd_cdc_tx_buffer_mask(cdc->tx_buf_ptr_in)] = data;
     cdc->tx_buf_ptr_in++;
-    if (check_overflow && usbd_cdc_tx_buffer_size(cdc) > USBD_CDC_TX_DATA_SIZE) {
+    if (check_overflow && usbd_cdc_tx_buffer_size(cdc) > MICROPY_HW_USB_CDC_TX_DATA_SIZE) {
         cdc->tx_buf_ptr_out++;
         cdc->tx_buf_ptr_out_next = cdc->tx_buf_ptr_out;
     }
@@ -270,7 +270,7 @@ void HAL_PCD_SOFCallback(PCD_HandleTypeDef *hpcd) {
 
 bool usbd_cdc_rx_buffer_full(usbd_cdc_itf_t *cdc) {
     int get = cdc->rx_buf_get, put = cdc->rx_buf_put;
-    int remaining = (get - put) + (-((int)(get <= put)) & USBD_CDC_RX_DATA_SIZE);
+    int remaining = (get - put) + (-((int)(get <= put)) & MICROPY_HW_USB_CDC_RX_DATA_SIZE);
     return remaining < CDC_DATA_MAX_PACKET_SIZE + 1;
 }
 
@@ -298,7 +298,7 @@ int8_t usbd_cdc_receive(usbd_cdc_state_t *cdc_in, size_t len) {
         if (cdc->attached_to_repl && *src == mp_interrupt_char) {
             pendsv_kbd_intr();
         } else {
-            uint16_t next_put = (cdc->rx_buf_put + 1) & (USBD_CDC_RX_DATA_SIZE - 1);
+            uint16_t next_put = (cdc->rx_buf_put + 1) & (MICROPY_HW_USB_CDC_RX_DATA_SIZE - 1);
             if (next_put == cdc->rx_buf_get) {
                 // overflow, we just discard the rest of the chars
                 break;
@@ -322,7 +322,7 @@ int8_t usbd_cdc_receive(usbd_cdc_state_t *cdc_in, size_t len) {
 
 int usbd_cdc_tx_half_empty(usbd_cdc_itf_t *cdc) {
     int32_t tx_waiting = usbd_cdc_tx_buffer_size(cdc);
-    return tx_waiting <= USBD_CDC_TX_DATA_SIZE / 2;
+    return tx_waiting <= MICROPY_HW_USB_CDC_TX_DATA_SIZE / 2;
 }
 
 // Writes only the data that fits if flow & CTS, else writes all data
@@ -405,7 +405,7 @@ void usbd_cdc_tx_always(usbd_cdc_itf_t *cdc, const uint8_t *buf, uint32_t len) {
 int usbd_cdc_rx_num(usbd_cdc_itf_t *cdc) {
     int32_t rx_waiting = (int32_t)cdc->rx_buf_put - (int32_t)cdc->rx_buf_get;
     if (rx_waiting < 0) {
-        rx_waiting += USBD_CDC_RX_DATA_SIZE;
+        rx_waiting += MICROPY_HW_USB_CDC_RX_DATA_SIZE;
     }
     usbd_cdc_rx_check_resume(cdc);
     return rx_waiting;
@@ -434,7 +434,7 @@ int usbd_cdc_rx(usbd_cdc_itf_t *cdc, uint8_t *buf, uint32_t len, uint32_t timeou
 
         // Copy byte from device to user buffer
         buf[i] = cdc->rx_user_buf[cdc->rx_buf_get];
-        cdc->rx_buf_get = (cdc->rx_buf_get + 1) & (USBD_CDC_RX_DATA_SIZE - 1);
+        cdc->rx_buf_get = (cdc->rx_buf_get + 1) & (MICROPY_HW_USB_CDC_RX_DATA_SIZE - 1);
     }
     usbd_cdc_rx_check_resume(cdc);
 
diff --git a/ports/stm32/usbd_cdc_interface.h b/ports/stm32/usbd_cdc_interface.h
index 6b510f239..76b5c9e79 100644
--- a/ports/stm32/usbd_cdc_interface.h
+++ b/ports/stm32/usbd_cdc_interface.h
@@ -31,12 +31,7 @@
   ******************************************************************************
   */
 
-#ifndef USBD_CDC_RX_DATA_SIZE
-#define USBD_CDC_RX_DATA_SIZE (1024) // this must be 2 or greater, and a power of 2
-#endif
-#ifndef USBD_CDC_TX_DATA_SIZE
-#define USBD_CDC_TX_DATA_SIZE (1024) // This must be a power of 2 and no greater than 16384
-#endif
+#include "py/mpconfig.h"
 
 // Values for connect_state
 #define USBD_CDC_CONNECT_STATE_DISCONNECTED (0)
@@ -52,14 +47,14 @@ typedef struct _usbd_cdc_itf_t {
     usbd_cdc_state_t base; // state for the base CDC layer
 
     uint8_t rx_packet_buf[CDC_DATA_MAX_PACKET_SIZE]; // received data from USB OUT endpoint is stored in this buffer
-    uint8_t rx_user_buf[USBD_CDC_RX_DATA_SIZE]; // received data is buffered here until the user reads it
+    uint8_t rx_user_buf[MICROPY_HW_USB_CDC_RX_DATA_SIZE]; // received data is buffered here until the user reads it
     volatile uint16_t rx_buf_put; // circular buffer index
     uint16_t rx_buf_get; // circular buffer index
     uint8_t rx_buf_full; // rx from host will be blocked while this is true
 
-    uint8_t tx_buf[USBD_CDC_TX_DATA_SIZE]; // data for USB IN endpoind is stored in this buffer
-    uint16_t tx_buf_ptr_in; // increment this pointer modulo USBD_CDC_TX_DATA_SIZE when new data is available
-    volatile uint16_t tx_buf_ptr_out; // increment this pointer modulo USBD_CDC_TX_DATA_SIZE when data is drained
+    uint8_t tx_buf[MICROPY_HW_USB_CDC_TX_DATA_SIZE]; // data for USB IN endpoind is stored in this buffer
+    uint16_t tx_buf_ptr_in; // increment this pointer modulo MICROPY_HW_USB_CDC_TX_DATA_SIZE when new data is available
+    volatile uint16_t tx_buf_ptr_out; // increment this pointer modulo MICROPY_HW_USB_CDC_TX_DATA_SIZE when data is drained
     uint16_t tx_buf_ptr_out_next; // next position of above once transmission finished
     uint8_t tx_need_empty_packet; // used to flush the USB IN endpoint if the last packet was exactly the endpoint packet size
 
diff --git a/ports/stm32/usbd_desc.c b/ports/stm32/usbd_desc.c
index aa6837163..fd50029fc 100644
--- a/ports/stm32/usbd_desc.c
+++ b/ports/stm32/usbd_desc.c
@@ -36,46 +36,14 @@
 // need this header just for MP_HAL_UNIQUE_ID_ADDRESS
 #include "py/mphal.h"
 
-// need this header for any overrides to the below constants
+// Need this header for MICROPY_HW_USB_xxx configuration values.
 #include "py/mpconfig.h"
 
-#ifndef USBD_LANGID_STRING
-#define USBD_LANGID_STRING            0x409
-#endif
-
-#ifndef USBD_MANUFACTURER_STRING
-#define USBD_MANUFACTURER_STRING      "MicroPython"
-#endif
-
-#ifndef USBD_PRODUCT_HS_STRING
-#define USBD_PRODUCT_HS_STRING        "Pyboard Virtual Comm Port in HS Mode"
-#endif
-
-#ifndef USBD_PRODUCT_FS_STRING
-#define USBD_PRODUCT_FS_STRING        "Pyboard Virtual Comm Port in FS Mode"
-#endif
-
-#ifndef USBD_CONFIGURATION_HS_STRING
-#define USBD_CONFIGURATION_HS_STRING  "Pyboard Config"
-#endif
-
-#ifndef USBD_INTERFACE_HS_STRING
-#define USBD_INTERFACE_HS_STRING      "Pyboard Interface"
-#endif
-
-#ifndef USBD_CONFIGURATION_FS_STRING
-#define USBD_CONFIGURATION_FS_STRING  "Pyboard Config"
-#endif
-
-#ifndef USBD_INTERFACE_FS_STRING
-#define USBD_INTERFACE_FS_STRING      "Pyboard Interface"
-#endif
-
 __ALIGN_BEGIN static const uint8_t USBD_LangIDDesc[USB_LEN_LANGID_STR_DESC] __ALIGN_END = {
     USB_LEN_LANGID_STR_DESC,
     USB_DESC_TYPE_STRING,
-    LOBYTE(USBD_LANGID_STRING),
-    HIBYTE(USBD_LANGID_STRING),
+    LOBYTE(MICROPY_HW_USB_LANGID_STRING),
+    HIBYTE(MICROPY_HW_USB_LANGID_STRING),
 };
 
 // set the VID, PID and device release number
@@ -140,14 +108,14 @@ STATIC uint8_t *USBD_StrDescriptor(USBD_HandleTypeDef *pdev, uint8_t idx, uint16
             return (uint8_t *)USBD_LangIDDesc; // the data should only be read from this buf
 
         case USBD_IDX_MFC_STR:
-            str = USBD_MANUFACTURER_STRING;
+            str = MICROPY_HW_USB_MANUFACTURER_STRING;
             break;
 
         case USBD_IDX_PRODUCT_STR:
             if (pdev->dev_speed == USBD_SPEED_HIGH) {
-                str = USBD_PRODUCT_HS_STRING;
+                str = MICROPY_HW_USB_PRODUCT_HS_STRING;
             } else {
-                str = USBD_PRODUCT_FS_STRING;
+                str = MICROPY_HW_USB_PRODUCT_FS_STRING;
             }
             break;
 
@@ -174,17 +142,17 @@ STATIC uint8_t *USBD_StrDescriptor(USBD_HandleTypeDef *pdev, uint8_t idx, uint16
 
         case USBD_IDX_CONFIG_STR:
             if (pdev->dev_speed == USBD_SPEED_HIGH) {
-                str = USBD_CONFIGURATION_HS_STRING;
+                str = MICROPY_HW_USB_CONFIGURATION_HS_STRING;
             } else {
-                str = USBD_CONFIGURATION_FS_STRING;
+                str = MICROPY_HW_USB_CONFIGURATION_FS_STRING;
             }
             break;
 
         case USBD_IDX_INTERFACE_STR:
             if (pdev->dev_speed == USBD_SPEED_HIGH) {
-                str = USBD_INTERFACE_HS_STRING;
+                str = MICROPY_HW_USB_INTERFACE_HS_STRING;
             } else {
-                str = USBD_INTERFACE_FS_STRING;
+                str = MICROPY_HW_USB_INTERFACE_FS_STRING;
             }
             break;
 
diff --git a/ports/teensy/Makefile b/ports/teensy/Makefile
index cf9529442..d1ff42162 100644
--- a/ports/teensy/Makefile
+++ b/ports/teensy/Makefile
@@ -100,12 +100,12 @@ STM_SRC_C = $(addprefix ports/stm32/,\
 	pin_named_pins.c \
 	)
 
-LIB_SRC_C = $(addprefix lib/,\
+SHARED_SRC_C = $(addprefix shared/,\
 	libc/string0.c \
-	mp-readline/readline.c \
-	utils/gchelper_native.c \
-	utils/pyexec.c \
-	utils/sys_stdio_mphal.c \
+	readline/readline.c \
+	runtime/gchelper_native.c \
+	runtime/pyexec.c \
+	runtime/sys_stdio_mphal.c \
 	)
 
 SRC_TEENSY = $(addprefix core/,\
@@ -120,8 +120,8 @@ SRC_TEENSY = $(addprefix core/,\
 	)
 
 OBJ = $(PY_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o) $(STM_SRC_C:.c=.o) $(SRC_TEENSY:.c=.o))
-OBJ += $(addprefix $(BUILD)/, $(LIB_SRC_C:.c=.o))
-OBJ += $(BUILD)/lib/utils/gchelper_m3.o
+OBJ += $(addprefix $(BUILD)/, $(SHARED_SRC_C:.c=.o))
+OBJ += $(BUILD)/shared/runtime/gchelper_m3.o
 OBJ += $(BUILD)/pins_gen.o
 
 all: hex
@@ -129,13 +129,13 @@ hex: $(BUILD)/micropython.hex
 
 ifeq ($(USE_MEMZIP),1)
 SRC_C += \
-	lib/memzip/import.c \
-	lib/memzip/lexermemzip.c \
-	lib/memzip/memzip.c \
+	shared/memzip/import.c \
+	shared/memzip/lexermemzip.c \
+	shared/memzip/memzip.c \
 
 OBJ += $(BUILD)/memzip-files.o
 
-MAKE_MEMZIP = $(TOP)/lib/memzip/make-memzip.py
+MAKE_MEMZIP = $(TOP)/shared/memzip/make-memzip.py
 ifeq ($(MEMZIP_DIR),)
 MEMZIP_DIR = memzip_files
 endif
@@ -207,7 +207,7 @@ GEN_PINS_AF_CONST = $(HEADER_BUILD)/pins_af_const.h
 GEN_PINS_AF_PY = $(BUILD)/pins_af.py
 
 # List of sources for qstr extraction
-SRC_QSTR += $(SRC_C) $(STM_SRC_C) $(LIB_SRC_C)
+SRC_QSTR += $(SRC_C) $(STM_SRC_C) $(SHARED_SRC_C)
 # Append any auto-generated sources that are needed by sources listed in
 # SRC_QSTR
 SRC_QSTR_AUTO_DEPS +=
diff --git a/ports/teensy/main.c b/ports/teensy/main.c
index d4c5f0396..6ebdcde21 100644
--- a/ports/teensy/main.c
+++ b/ports/teensy/main.c
@@ -9,9 +9,9 @@
 #include "py/gc.h"
 #include "py/mphal.h"
 #include "gccollect.h"
-#include "lib/utils/gchelper.h"
-#include "lib/utils/pyexec.h"
-#include "lib/mp-readline/readline.h"
+#include "shared/readline/readline.h"
+#include "shared/runtime/gchelper.h"
+#include "shared/runtime/pyexec.h"
 #include "lexermemzip.h"
 
 #include "Arduino.h"
diff --git a/ports/teensy/modpyb.c b/ports/teensy/modpyb.c
index 6671b3abd..f5bb3ea7b 100644
--- a/ports/teensy/modpyb.c
+++ b/ports/teensy/modpyb.c
@@ -33,7 +33,7 @@
 #include "py/gc.h"
 #include "py/mphal.h"
 
-#include "lib/utils/pyexec.h"
+#include "shared/runtime/pyexec.h"
 
 #include "gccollect.h"
 #include "systick.h"
diff --git a/ports/unix/Makefile b/ports/unix/Makefile
index fbd439227..efcc437e4 100644
--- a/ports/unix/Makefile
+++ b/ports/unix/Makefile
@@ -118,9 +118,9 @@ endif
 endif
 
 ifeq ($(MICROPY_USE_READLINE),1)
-INC +=  -I$(TOP)/lib/mp-readline
+INC += -I$(TOP)/shared/readline
 CFLAGS_MOD += -DMICROPY_USE_READLINE=1
-LIB_SRC_C_EXTRA += mp-readline/readline.c
+SHARED_SRC_C_EXTRA += readline/readline.c
 endif
 ifeq ($(MICROPY_PY_TERMIOS),1)
 CFLAGS_MOD += -DMICROPY_PY_TERMIOS=1
@@ -247,8 +247,12 @@ LIB_SRC_C += $(addprefix lib/,\
     lv_bindings/driver/SDL/SDL_mouse.c \
 	lv_bindings/driver/SDL/modSDL.c \
 	$(LIB_SRC_C_EXTRA) \
+	)
+
+SHARED_SRC_C += $(addprefix shared/,\
+	runtime/gchelper_generic.c \
 	timeutils/timeutils.c \
-	utils/gchelper_generic.c \
+	$(SHARED_SRC_C_EXTRA) \
 	)
 
 ifneq ($(UNAME_S),Darwin)
@@ -263,11 +267,12 @@ SRC_CXX += \
 OBJ = $(PY_O)
 OBJ += $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_CXX:.cpp=.o))
-OBJ += $(addprefix $(BUILD)/, $(LIB_SRC_C:.c=.o))
+OBJ += $(addprefix $(BUILD)/, $(SHARED_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(EXTMOD_SRC_C:.c=.o))
+OBJ += $(addprefix $(BUILD)/, $(LIB_SRC_C:.c=.o))
 
 # List of sources for qstr extraction
-SRC_QSTR += $(SRC_C) $(SRC_CXX) $(LIB_SRC_C) $(EXTMOD_SRC_C)
+SRC_QSTR += $(SRC_C) $(SRC_CXX) $(LIB_SRC_C) $(SHARED_SRC_C) $(EXTMOD_SRC_C)
 # Append any auto-generated sources that are needed by sources listed in
 # SRC_QSTR
 SRC_QSTR_AUTO_DEPS +=
@@ -299,6 +304,17 @@ else
 RUN_TESTS_MPY_CROSS_FLAGS = --mpy-cross-flags='-mcache-lookup-bc'
 endif
 
+ifeq ($(CROSS_COMPILE),arm-linux-gnueabi-)
+# Force disable error text compression when compiling for ARM as the compiler
+# cannot optimise out the giant strcmp list generated for MP_MATCH_COMPRESSED.
+# Checked on:
+# arm-linux-gnueabi-gcc (Ubuntu/Linaro 7.5.0-3ubuntu1~18.04) 7.5.0
+# arm-linux-gnueabi-gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0
+# See https://github.com/micropython/micropython/pull/7659 for details.
+$(info Detected arm-linux-gnueabi-gcc. Disabling error message compression.)
+MICROPY_ROM_TEXT_COMPRESSION = 0
+endif
+
 include $(TOP)/py/mkrules.mk
 
 .PHONY: test test_full
diff --git a/ports/unix/gccollect.c b/ports/unix/gccollect.c
index f0441e4ea..79b17663c 100644
--- a/ports/unix/gccollect.c
+++ b/ports/unix/gccollect.c
@@ -29,7 +29,7 @@
 #include "py/mpstate.h"
 #include "py/gc.h"
 
-#include "lib/utils/gchelper.h"
+#include "shared/runtime/gchelper.h"
 
 #if MICROPY_ENABLE_GC
 
diff --git a/ports/unix/input.c b/ports/unix/input.c
index 4a77d1b27..c5bf71973 100644
--- a/ports/unix/input.c
+++ b/ports/unix/input.c
@@ -35,7 +35,7 @@
 #include "input.h"
 
 #if MICROPY_USE_READLINE == 1
-#include "lib/mp-readline/readline.h"
+#include "shared/readline/readline.h"
 #endif
 
 #if MICROPY_USE_READLINE == 0
diff --git a/ports/unix/main.c b/ports/unix/main.c
index a5db0869d..031bdd75d 100644
--- a/ports/unix/main.c
+++ b/ports/unix/main.c
@@ -159,7 +159,7 @@ STATIC int execute_from_lexer(int source_kind, const void *source, mp_parse_inpu
 }
 
 #if MICROPY_USE_READLINE == 1
-#include "lib/mp-readline/readline.h"
+#include "shared/readline/readline.h"
 #else
 STATIC char *strjoin(const char *s1, int sep_char, const char *s2) {
     int l1 = strlen(s1);
diff --git a/ports/unix/modjni.c b/ports/unix/modjni.c
index 74e7221de..bd151050e 100644
--- a/ports/unix/modjni.c
+++ b/ports/unix/modjni.c
@@ -102,9 +102,9 @@ STATIC void check_exception(void) {
         mp_obj_t py_e = new_jobject(exc);
         JJ1(ExceptionClear);
         if (JJ(IsInstanceOf, exc, IndexException_class)) {
-            nlr_raise(mp_obj_new_exception_arg1(&mp_type_IndexError, py_e));
+            mp_raise_type_arg(&mp_type_IndexError, py_e);
         }
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_Exception, py_e));
+        mp_raise_type_arg(&mp_type_Exception, py_e);
     }
 }
 
diff --git a/ports/unix/mpconfigport.h b/ports/unix/mpconfigport.h
index 00c6607f5..b8bfbd2b8 100644
--- a/ports/unix/mpconfigport.h
+++ b/ports/unix/mpconfigport.h
@@ -90,6 +90,7 @@
 #define MICROPY_PY_FUNCTION_ATTRS   (1)
 #define MICROPY_PY_DESCRIPTORS      (1)
 #define MICROPY_PY_DELATTR_SETATTR  (1)
+#define MICROPY_PY_FSTRINGS         (1)
 #define MICROPY_PY_BUILTINS_STR_UNICODE (1)
 #define MICROPY_PY_BUILTINS_STR_CENTER (1)
 #define MICROPY_PY_BUILTINS_STR_PARTITION (1)
diff --git a/ports/unix/mphalport.h b/ports/unix/mphalport.h
index 89d23ca5d..510f9d939 100644
--- a/ports/unix/mphalport.h
+++ b/ports/unix/mphalport.h
@@ -52,7 +52,7 @@ static inline int mp_hal_readline(vstr_t *vstr, const char *p) {
 #elif MICROPY_PY_BUILTINS_INPUT && MICROPY_USE_READLINE == 1
 
 #include "py/misc.h"
-#include "lib/mp-readline/readline.h"
+#include "shared/readline/readline.h"
 // For built-in input() we need to wrap the standard readline() to enable raw mode
 #define mp_hal_readline mp_hal_readline
 static inline int mp_hal_readline(vstr_t *vstr, const char *p) {
diff --git a/ports/unix/mpthreadport.c b/ports/unix/mpthreadport.c
index d3243b337..63aac1da3 100644
--- a/ports/unix/mpthreadport.c
+++ b/ports/unix/mpthreadport.c
@@ -39,7 +39,7 @@
 #include <sched.h>
 #include <semaphore.h>
 
-#include "lib/utils/gchelper.h"
+#include "shared/runtime/gchelper.h"
 
 // Some platforms don't have SIGRTMIN but if we do have it, use it to avoid
 // potential conflict with other uses of the more commonly used SIGUSR1.
diff --git a/ports/unix/variants/dev/mpconfigvariant.h b/ports/unix/variants/dev/mpconfigvariant.h
index a12fb7725..6f54abdf9 100644
--- a/ports/unix/variants/dev/mpconfigvariant.h
+++ b/ports/unix/variants/dev/mpconfigvariant.h
@@ -31,6 +31,8 @@
 #define MICROPY_VFS                             (1)
 #define MICROPY_VFS_POSIX                       (1)
 
+#define MICROPY_PY_BUILTINS_HELP                (1)
+#define MICROPY_PY_BUILTINS_HELP_MODULES        (1)
 #define MICROPY_PY_SYS_SETTRACE                 (0)
 #define MICROPY_PY_UOS_VFS                      (1)
 #define MICROPY_PY_URANDOM_EXTRA_FUNCS          (1)
diff --git a/ports/unix/variants/standard/mpconfigvariant.h b/ports/unix/variants/standard/mpconfigvariant.h
index 79b8fe2a3..3cdcfa8e9 100644
--- a/ports/unix/variants/standard/mpconfigvariant.h
+++ b/ports/unix/variants/standard/mpconfigvariant.h
@@ -24,3 +24,5 @@
  * THE SOFTWARE.
  */
 
+#define MICROPY_PY_BUILTINS_HELP                (1)
+#define MICROPY_PY_BUILTINS_HELP_MODULES        (1)
diff --git a/ports/windows/.appveyor.yml b/ports/windows/.appveyor.yml
index 1ec72bbb3..40fdff293 100644
--- a/ports/windows/.appveyor.yml
+++ b/ports/windows/.appveyor.yml
@@ -1,10 +1,10 @@
-image: Visual Studio 2013
+image: Visual Studio 2017
 clone_depth: 1
 skip_tags: true
 
 environment:
   # Python version used
-  MICROPY_CPYTHON3: c:/python34/python.exe
+  MICROPY_CPYTHON3: c:/python38/python.exe
 
 init:
   # Set build version number to commit to be travis-like
@@ -63,10 +63,7 @@ after_test:
       throw "$env:MSYSTEM build exited with code $LASTEXITCODE"
     }
     cd (Join-Path $env:APPVEYOR_BUILD_FOLDER 'mpy-cross')
-    # Building of mpy-cross hasn't been fixed across all possible windows/WSL/...
-    # variations and the STRIP step tries to strip mpy-cross whereas that should be
-    # mpy-cross.exe. Workaround for now by skipping actual strip and size commands.
-    C:\msys64\usr\bin\bash.exe -l -c "make -B -j4 V=1 STRIP=echo SIZE=echo"
+    C:\msys64\usr\bin\bash.exe -l -c "make -B -j4 V=1"
     if ($LASTEXITCODE -ne 0) {
       throw "$env:MSYSTEM mpy_cross build exited with code $LASTEXITCODE"
     }
diff --git a/ports/windows/Makefile b/ports/windows/Makefile
index 5ee4bdc8a..c5b5e879e 100644
--- a/ports/windows/Makefile
+++ b/ports/windows/Makefile
@@ -2,7 +2,7 @@ include ../../py/mkenv.mk
 -include mpconfigport.mk
 
 # define main target
-PROG = micropython.exe
+PROG = micropython
 
 # qstr definitions (must come before including py.mk)
 QSTR_DEFS = ../unix/qstrdefsport.h
@@ -28,8 +28,8 @@ endif
 
 # source files
 SRC_C = \
-	lib/utils/gchelper_generic.c \
-	lib/utils/printf.c \
+	shared/libc/printf.c \
+	shared/runtime/gchelper_generic.c \
 	ports/unix/main.c \
 	ports/unix/input.c \
 	ports/unix/modos.c \
@@ -55,7 +55,7 @@ OBJ += $(addprefix $(BUILD)/, $(LIB_SRC_C:.c=.o))
 
 ifeq ($(MICROPY_USE_READLINE),1)
 CFLAGS_MOD += -DMICROPY_USE_READLINE=1
-SRC_C += lib/mp-readline/readline.c
+SRC_C += shared/readline/readline.c
 endif
 
 LIB += -lws2_32 -lSDL2
diff --git a/ports/windows/micropython.vcxproj b/ports/windows/micropython.vcxproj
index 73a837a84..1beca9e50 100644
--- a/ports/windows/micropython.vcxproj
+++ b/ports/windows/micropython.vcxproj
@@ -85,8 +85,8 @@
   <ItemGroup>
     <ClCompile Include="@(PyCoreSource)" />
     <ClCompile Include="@(PyExtModSource)" />
-    <ClCompile Include="$(PyBaseDir)lib\mp-readline\*.c" />
-    <ClCompile Include="$(PyBaseDir)lib\utils\gchelper_generic.c" />
+    <ClCompile Include="$(PyBaseDir)shared\readline\*.c" />
+    <ClCompile Include="$(PyBaseDir)shared\runtime\gchelper_generic.c" />
     <ClCompile Include="$(PyBaseDir)ports\windows\*.c" />
     <ClCompile Include="$(PyBaseDir)ports\windows\msvc\*.c" />
     <ClCompile Include="$(PyBaseDir)ports\unix\gccollect.c"/>
@@ -109,4 +109,4 @@
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/ports/windows/mpconfigport.h b/ports/windows/mpconfigport.h
index 0107116c3..a8340e9a2 100644
--- a/ports/windows/mpconfigport.h
+++ b/ports/windows/mpconfigport.h
@@ -67,6 +67,7 @@
 #define MICROPY_PY_FUNCTION_ATTRS   (1)
 #define MICROPY_PY_DESCRIPTORS      (1)
 #define MICROPY_PY_DELATTR_SETATTR  (1)
+#define MICROPY_PY_FSTRINGS         (1)
 #define MICROPY_PY_BUILTINS_STR_UNICODE (1)
 #define MICROPY_PY_BUILTINS_STR_CENTER (1)
 #define MICROPY_PY_BUILTINS_STR_PARTITION (1)
diff --git a/ports/zephyr/CMakeLists.txt b/ports/zephyr/CMakeLists.txt
index 80adea5d8..ca18f2cb9 100644
--- a/ports/zephyr/CMakeLists.txt
+++ b/ports/zephyr/CMakeLists.txt
@@ -38,6 +38,7 @@ set(MICROPY_SOURCE_PORT
     main.c
     help.c
     machine_i2c.c
+    machine_spi.c
     machine_pin.c
     machine_uart.c
     modbluetooth_zephyr.c
@@ -53,14 +54,18 @@ set(MICROPY_SOURCE_PORT
 )
 list(TRANSFORM MICROPY_SOURCE_PORT PREPEND ${MICROPY_PORT_DIR}/)
 
-set(MICROPY_SOURCE_LIB
+set(MICROPY_SOURCE_SHARED
+    libc/printf.c
+    readline/readline.c
+    runtime/interrupt_char.c
+    runtime/mpirq.c
+    runtime/pyexec.c
+    runtime/stdout_helpers.c
     timeutils/timeutils.c
-    utils/mpirq.c
-    utils/stdout_helpers.c
-    utils/printf.c
-    utils/pyexec.c
-    utils/interrupt_char.c
-    mp-readline/readline.c
+)
+list(TRANSFORM MICROPY_SOURCE_SHARED PREPEND ${MICROPY_DIR}/shared/)
+
+set(MICROPY_SOURCE_LIB
     oofatfs/ff.c
     oofatfs/ffunicode.c
     littlefs/lfs1.c
@@ -73,6 +78,7 @@ list(TRANSFORM MICROPY_SOURCE_LIB PREPEND ${MICROPY_DIR}/lib/)
 set(MICROPY_SOURCE_QSTR
     ${MICROPY_SOURCE_PY}
     ${MICROPY_SOURCE_EXTMOD}
+    ${MICROPY_SOURCE_SHARED}
     ${MICROPY_SOURCE_LIB}
     ${MICROPY_SOURCE_PORT}
 )
diff --git a/ports/zephyr/README.md b/ports/zephyr/README.md
index 9d6c223b4..e0b02af22 100644
--- a/ports/zephyr/README.md
+++ b/ports/zephyr/README.md
@@ -15,6 +15,7 @@ Features supported at this time:
 * `utime` module for time measurements and delays.
 * `machine.Pin` class for GPIO control, with IRQ support.
 * `machine.I2C` class for I2C control.
+* `machine.SPI` class for SPI control.
 * `usocket` module for networking (IPv4/IPv6).
 * "Frozen modules" support to allow to bundle Python modules together
   with firmware. Including complete applications, including with
@@ -135,6 +136,14 @@ Example of using I2C to scan for I2C slaves:
     i2c = I2C("I2C_0")
     i2c.scan()
 
+Example of using SPI to write a buffer to the MOSI pin:
+
+    from machine import SPI
+
+    spi = SPI("SPI_0")
+    spi.init(baudrate=500000, polarity=1, phase=1, bits=8, firstbit=SPI.MSB)
+    spi.write(b'abcd')
+
 
 Minimal build
 -------------
diff --git a/ports/zephyr/boards/frdm_k64f.conf b/ports/zephyr/boards/frdm_k64f.conf
index 483e9a29b..c164c0c32 100644
--- a/ports/zephyr/boards/frdm_k64f.conf
+++ b/ports/zephyr/boards/frdm_k64f.conf
@@ -3,6 +3,7 @@ CONFIG_NET_L2_ETHERNET=y
 
 # Hardware features
 CONFIG_I2C=y
+CONFIG_SPI=y
 
 # Sensor drivers
 CONFIG_FXOS8700=y
diff --git a/ports/zephyr/boards/mimxrt685_evk_cm33.conf b/ports/zephyr/boards/mimxrt685_evk_cm33.conf
new file mode 100644
index 000000000..827222b88
--- /dev/null
+++ b/ports/zephyr/boards/mimxrt685_evk_cm33.conf
@@ -0,0 +1,2 @@
+# Hardware features
+CONFIG_SPI=y
diff --git a/ports/zephyr/machine_pin.c b/ports/zephyr/machine_pin.c
index 34c822c2f..f9da2433c 100644
--- a/ports/zephyr/machine_pin.c
+++ b/ports/zephyr/machine_pin.c
@@ -35,7 +35,7 @@
 #include "py/runtime.h"
 #include "py/gc.h"
 #include "py/mphal.h"
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/mpirq.h"
 #include "modmachine.h"
 
 #if MICROPY_PY_MACHINE
diff --git a/ports/zephyr/machine_spi.c b/ports/zephyr/machine_spi.c
new file mode 100644
index 000000000..2add7ff60
--- /dev/null
+++ b/ports/zephyr/machine_spi.c
@@ -0,0 +1,211 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright 2021 NXP
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <zephyr.h>
+#include <drivers/spi.h>
+
+#include "py/runtime.h"
+#include "py/gc.h"
+#include "py/mphal.h"
+#include "py/mperrno.h"
+#include "extmod/machine_spi.h"
+#include "modmachine.h"
+
+#if MICROPY_PY_MACHINE_SPI
+
+#define DEFAULT_SPI_BAUDRATE    (50000)
+#define DEFAULT_SPI_POLARITY    (0)
+#define DEFAULT_SPI_PHASE       (0)
+#define DEFAULT_SPI_BITS        (8)
+#define DEFAULT_SPI_FIRSTBIT    (SPI_TRANSFER_MSB)
+#define SPI_LOOP                (0)    // For testing, enable loop mode by setting SPI_LOOP (1)
+
+typedef struct _machine_hard_spi_obj_t {
+    mp_obj_base_t base;
+    const struct device *dev;
+    struct spi_config config;
+} machine_hard_spi_obj_t;
+
+STATIC void machine_hard_spi_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_hard_spi_obj_t *self = self_in;
+    mp_printf(print, "SPI(%s, baudrate=%u, polarity=%u, phase=%u, bits=%u, firstbit=%s)",
+        self->dev->name,
+        self->config.frequency,
+        (self->config.operation & 0x2) >> 1,
+        (self->config.operation & 0x4) >> 2,
+        (self->config.operation & ~0x1F) >> 5,
+        ((self->config.operation & 0x10) >> 4) == SPI_TRANSFER_MSB ? "MSB" : "LSB");
+}
+
+mp_obj_t machine_hard_spi_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
+    enum {ARG_id, ARG_baudrate, ARG_polarity, ARG_phase, ARG_bits, ARG_firstbit, ARG_sck, ARG_mosi, ARG_miso};
+
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = DEFAULT_SPI_BAUDRATE} },
+        { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = DEFAULT_SPI_POLARITY} },
+        { MP_QSTR_phase, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = DEFAULT_SPI_PHASE} },
+        { MP_QSTR_bits, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = DEFAULT_SPI_BITS} },
+        { MP_QSTR_firstbit, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = DEFAULT_SPI_FIRSTBIT} },
+        { MP_QSTR_sck, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_mosi, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_miso, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    };
+
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    const char *dev_name = mp_obj_str_get_str(args[ARG_id].u_obj);
+    const struct device *dev = device_get_binding(dev_name);
+
+    if (dev == NULL) {
+        mp_raise_ValueError(MP_ERROR_TEXT("device not found"));
+    }
+
+    if ((args[ARG_sck].u_obj != MP_OBJ_NULL) || (args[ARG_miso].u_obj != MP_OBJ_NULL) || (args[ARG_mosi].u_obj != MP_OBJ_NULL)) {
+        mp_raise_NotImplementedError(MP_ERROR_TEXT("explicit choice of sck/miso/mosi is not implemented"));
+    }
+
+    struct spi_config cfg = {
+        .frequency = args[ARG_baudrate].u_int,
+        .operation = (SPI_OP_MODE_MASTER |
+            args[ARG_polarity].u_int << 1 |
+                args[ARG_phase].u_int << 2 |
+                SPI_LOOP << 3 |
+                args[ARG_firstbit].u_int << 4 |
+                args[ARG_bits].u_int << 5 |
+                SPI_LINES_SINGLE),
+        .slave = 0,
+        .cs = NULL
+    };
+
+    machine_hard_spi_obj_t *self = m_new_obj(machine_hard_spi_obj_t);
+
+    self->base.type = &machine_hard_spi_type;
+    self->dev = dev;
+    self->config = cfg;
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC void machine_hard_spi_init(mp_obj_base_t *obj, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum {ARG_baudrate, ARG_polarity, ARG_phase, ARG_bits, ARG_firstbit};
+
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_baudrate, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_phase, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_bits, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_firstbit, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+    };
+
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    machine_hard_spi_obj_t *self = (machine_hard_spi_obj_t *)obj;
+
+    uint32_t baudrate;
+    uint16_t operation = self->config.operation;
+
+    if (args[ARG_baudrate].u_int != -1) {
+        baudrate = args[ARG_baudrate].u_int;
+    } else {
+        baudrate = self->config.frequency;
+    }
+
+    if (args[ARG_polarity].u_int != -1) {
+        operation = (operation & ~0x2) | (args[ARG_polarity].u_int << 1);
+    }
+
+    if (args[ARG_phase].u_int != -1) {
+        operation = (operation & ~0x4) | (args[ARG_phase].u_int << 2);
+    }
+
+    if (args[ARG_bits].u_int != -1) {
+        operation = (operation & 0x1F) | (args[ARG_bits].u_int << 5);
+    }
+
+    if (args[ARG_firstbit].u_int != -1) {
+        operation = (operation & ~0x10) | (args[ARG_firstbit].u_int << 4);
+    }
+
+    struct spi_config cfg = {
+        .frequency = baudrate,
+        .operation = operation,
+        .slave = 0,
+        .cs = NULL
+    };
+
+    self->config = cfg;
+}
+
+STATIC void machine_hard_spi_transfer(mp_obj_base_t *obj, size_t len, const uint8_t *src, uint8_t *dest) {
+    machine_hard_spi_obj_t *self = (machine_hard_spi_obj_t *)obj;
+
+    int ret;
+
+    struct spi_buf tx_bufs[1];
+    tx_bufs[0].buf = (uint8_t *)src;
+    tx_bufs[0].len = len;
+    const struct spi_buf_set tx = {
+        .buffers = tx_bufs,
+        .count = ARRAY_SIZE(tx_bufs)
+    };
+
+    struct spi_buf rx_bufs[1];
+    rx_bufs[0].buf = dest;
+    rx_bufs[0].len = len;
+    const struct spi_buf_set rx = {
+        .buffers = rx_bufs,
+        .count = ARRAY_SIZE(rx_bufs)
+    };
+
+    ret = spi_transceive(self->dev, &self->config, &tx, &rx);
+
+    if (ret < 0) {
+        mp_raise_OSError(-ret);
+    }
+}
+
+STATIC const mp_machine_spi_p_t machine_hard_spi_p = {
+    .init = machine_hard_spi_init,
+    .transfer = machine_hard_spi_transfer,
+};
+
+const mp_obj_type_t machine_hard_spi_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_SPI,
+    .print = machine_hard_spi_print,
+    .make_new = machine_hard_spi_make_new,
+    .protocol = &machine_hard_spi_p,
+    .locals_dict = (mp_obj_dict_t *)&mp_machine_spi_locals_dict,
+};
+
+#endif // MICROPY_PY_MACHINE_SPI
diff --git a/ports/zephyr/main.c b/ports/zephyr/main.c
index 38285ad94..63190bd5e 100644
--- a/ports/zephyr/main.c
+++ b/ports/zephyr/main.c
@@ -47,8 +47,8 @@
 #include "py/gc.h"
 #include "py/mphal.h"
 #include "py/stackctrl.h"
-#include "lib/utils/pyexec.h"
-#include "lib/mp-readline/readline.h"
+#include "shared/runtime/pyexec.h"
+#include "shared/readline/readline.h"
 #include "extmod/modbluetooth.h"
 
 #if MICROPY_VFS
@@ -59,9 +59,9 @@
 #include "modzephyr.h"
 
 #ifdef TEST
-#include "lib/upytesthelper/upytesthelper.h"
+#include "shared/upytesthelper/upytesthelper.h"
 #include "lib/tinytest/tinytest.c"
-#include "lib/upytesthelper/upytesthelper.c"
+#include "shared/upytesthelper/upytesthelper.c"
 #include TEST
 #endif
 
diff --git a/ports/zephyr/modbluetooth_zephyr.c b/ports/zephyr/modbluetooth_zephyr.c
index 6b3a10d47..5753d7147 100644
--- a/ports/zephyr/modbluetooth_zephyr.c
+++ b/ports/zephyr/modbluetooth_zephyr.c
@@ -308,10 +308,13 @@ int mp_bluetooth_gatts_read(uint16_t value_handle, uint8_t **value, size_t *valu
     return mp_bluetooth_gatts_db_read(MP_STATE_PORT(bluetooth_zephyr_root_pointers)->gatts_db, value_handle, value, value_len);
 }
 
-int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len) {
+int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len, bool send_update) {
     if (!mp_bluetooth_is_active()) {
         return ERRNO_BLUETOOTH_NOT_ACTIVE;
     }
+    if (send_update) {
+        return MP_EOPNOTSUPP;
+    }
     return mp_bluetooth_gatts_db_write(MP_STATE_PORT(bluetooth_zephyr_root_pointers)->gatts_db, value_handle, value, value_len);
 }
 
diff --git a/ports/zephyr/modmachine.c b/ports/zephyr/modmachine.c
index 4353083ee..adec9160b 100644
--- a/ports/zephyr/modmachine.c
+++ b/ports/zephyr/modmachine.c
@@ -36,6 +36,7 @@
 #include "extmod/machine_signal.h"
 #include "extmod/machine_pulse.h"
 #include "extmod/machine_i2c.h"
+#include "extmod/machine_spi.h"
 #include "modmachine.h"
 
 #if MICROPY_PY_MACHINE
@@ -70,6 +71,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     #if MICROPY_PY_MACHINE_I2C
     { MP_ROM_QSTR(MP_QSTR_I2C), MP_ROM_PTR(&machine_hard_i2c_type) },
     #endif
+    #if MICROPY_PY_MACHINE_SPI
+    { MP_ROM_QSTR(MP_QSTR_SPI), MP_ROM_PTR(&machine_hard_spi_type) },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_UART), MP_ROM_PTR(&machine_uart_type) },
     { MP_ROM_QSTR(MP_QSTR_Pin), MP_ROM_PTR(&machine_pin_type) },
     { MP_ROM_QSTR(MP_QSTR_Signal), MP_ROM_PTR(&machine_signal_type) },
diff --git a/ports/zephyr/modmachine.h b/ports/zephyr/modmachine.h
index 957f2dd4f..a3cdd2b30 100644
--- a/ports/zephyr/modmachine.h
+++ b/ports/zephyr/modmachine.h
@@ -5,6 +5,7 @@
 
 extern const mp_obj_type_t machine_pin_type;
 extern const mp_obj_type_t machine_hard_i2c_type;
+extern const mp_obj_type_t machine_hard_spi_type;
 extern const mp_obj_type_t machine_uart_type;
 
 MP_DECLARE_CONST_FUN_OBJ_0(machine_info_obj);
diff --git a/ports/zephyr/mpconfigport.h b/ports/zephyr/mpconfigport.h
index e5fb32d6b..1768d2e82 100644
--- a/ports/zephyr/mpconfigport.h
+++ b/ports/zephyr/mpconfigport.h
@@ -29,6 +29,7 @@
 #include "autoconf.h"
 // Included here to get basic Zephyr environment (macros, etc.)
 #include <zephyr.h>
+#include <drivers/spi.h>
 
 // Usually passed from Makefile
 #ifndef MICROPY_HEAP_SIZE
@@ -66,6 +67,9 @@
 #define MICROPY_PY_MICROPYTHON_MEM_INFO (1)
 #define MICROPY_PY_MACHINE          (1)
 #define MICROPY_PY_MACHINE_I2C      (1)
+#define MICROPY_PY_MACHINE_SPI      (1)
+#define MICROPY_PY_MACHINE_SPI_MSB (SPI_TRANSFER_MSB)
+#define MICROPY_PY_MACHINE_SPI_LSB (SPI_TRANSFER_LSB)
 #define MICROPY_PY_MACHINE_PIN_MAKE_NEW mp_pin_make_new
 #define MICROPY_MODULE_WEAK_LINKS   (1)
 #define MICROPY_PY_STRUCT           (0)
diff --git a/ports/zephyr/mpconfigport_bin_testsuite.h b/ports/zephyr/mpconfigport_bin_testsuite.h
index 684b4f41c..4367067af 100644
--- a/ports/zephyr/mpconfigport_bin_testsuite.h
+++ b/ports/zephyr/mpconfigport_bin_testsuite.h
@@ -26,6 +26,6 @@
 #include "mpconfigport.h"
 
 #ifdef TEST
-#include "lib/upytesthelper/upytesthelper.h"
+#include "shared/upytesthelper/upytesthelper.h"
 #define MP_PLAT_PRINT_STRN(str, len) upytest_output(str, len)
 #endif
diff --git a/ports/zephyr/mphalport.h b/ports/zephyr/mphalport.h
index 63a18e138..ba902a76a 100644
--- a/ports/zephyr/mphalport.h
+++ b/ports/zephyr/mphalport.h
@@ -1,5 +1,5 @@
 #include <zephyr.h>
-#include "lib/utils/interrupt_char.h"
+#include "shared/runtime/interrupt_char.h"
 
 void mp_hal_init(void);
 void mp_hal_wait_sem(struct k_sem *sem, uint32_t timeout_ms);
diff --git a/py/builtinimport.c b/py/builtinimport.c
index abbeefced..cdee5e407 100644
--- a/py/builtinimport.c
+++ b/py/builtinimport.c
@@ -142,7 +142,7 @@ STATIC void do_load_from_lexer(mp_obj_t module_obj, mp_lexer_t *lex) {
 }
 #endif
 
-#if MICROPY_PERSISTENT_CODE_LOAD || MICROPY_MODULE_FROZEN_MPY
+#if (MICROPY_HAS_FILE_READER && MICROPY_PERSISTENT_CODE_LOAD) || MICROPY_MODULE_FROZEN_MPY
 STATIC void do_execute_raw_code(mp_obj_t module_obj, mp_raw_code_t *raw_code, const char *source_name) {
     (void)source_name;
 
diff --git a/py/dynruntime.h b/py/dynruntime.h
index a8256c194..fdb91ed37 100644
--- a/py/dynruntime.h
+++ b/py/dynruntime.h
@@ -215,6 +215,7 @@ static inline mp_obj_t mp_obj_len_dyn(mp_obj_t o) {
 #define mp_obj_new_exception_arg1(e_type, arg)  (mp_obj_new_exception_arg1_dyn((e_type), (arg)))
 
 #define nlr_raise(o)                            (mp_raise_dyn(o))
+#define mp_raise_type_arg(type, arg)            (mp_raise_dyn(mp_obj_new_exception_arg1_dyn((type), (arg))))
 #define mp_raise_msg(type, msg)                 (mp_fun_table.raise_msg((type), (msg)))
 #define mp_raise_OSError(er)                    (mp_raise_OSError_dyn(er))
 #define mp_raise_NotImplementedError(msg)       (mp_raise_msg(&mp_type_NotImplementedError, (msg)))
diff --git a/py/emitnative.c b/py/emitnative.c
index 425ba2d33..7c7c34283 100644
--- a/py/emitnative.c
+++ b/py/emitnative.c
@@ -841,10 +841,13 @@ STATIC void need_reg_single(emit_t *emit, int reg_needed, int skip_stack_pos) {
     }
 }
 
+// Ensures all unsettled registers that hold Python values are copied to the
+// concrete Python stack.  All registers are then free to use.
 STATIC void need_reg_all(emit_t *emit) {
     for (int i = 0; i < emit->stack_size; i++) {
         stack_info_t *si = &emit->stack_info[i];
         if (si->kind == STACK_REG) {
+            DEBUG_printf("    reg(%u) to local(%u)\n", si->data.u_reg, emit->stack_start + i);
             si->kind = STACK_VALUE;
             emit_native_mov_state_reg(emit, emit->stack_start + i, si->data.u_reg);
         }
@@ -871,23 +874,21 @@ STATIC vtype_kind_t load_reg_stack_imm(emit_t *emit, int reg_dest, const stack_i
     }
 }
 
+// Copies all unsettled registers and immediates that are Python values into the
+// concrete Python stack.  This ensures the concrete Python stack holds valid
+// values for the current stack_size.
+// This function may clobber REG_TEMP1.
 STATIC void need_stack_settled(emit_t *emit) {
     DEBUG_printf("  need_stack_settled; stack_size=%d\n", emit->stack_size);
-    for (int i = 0; i < emit->stack_size; i++) {
-        stack_info_t *si = &emit->stack_info[i];
-        if (si->kind == STACK_REG) {
-            DEBUG_printf("    reg(%u) to local(%u)\n", si->data.u_reg, emit->stack_start + i);
-            si->kind = STACK_VALUE;
-            emit_native_mov_state_reg(emit, emit->stack_start + i, si->data.u_reg);
-        }
-    }
+    need_reg_all(emit);
     for (int i = 0; i < emit->stack_size; i++) {
         stack_info_t *si = &emit->stack_info[i];
         if (si->kind == STACK_IMM) {
             DEBUG_printf("    imm(" INT_FMT ") to local(%u)\n", si->data.u_imm, emit->stack_start + i);
             si->kind = STACK_VALUE;
-            si->vtype = load_reg_stack_imm(emit, REG_TEMP0, si, false);
-            emit_native_mov_state_reg(emit, emit->stack_start + i, REG_TEMP0);
+            // using REG_TEMP1 to avoid clobbering REG_TEMP0 (aka REG_RET)
+            si->vtype = load_reg_stack_imm(emit, REG_TEMP1, si, false);
+            emit_native_mov_state_reg(emit, emit->stack_start + i, REG_TEMP1);
         }
     }
 }
diff --git a/py/lexer.c b/py/lexer.c
index 07ea2b96a..69c7d14a7 100644
--- a/py/lexer.c
+++ b/py/lexer.c
@@ -62,6 +62,12 @@ STATIC bool is_char_or3(mp_lexer_t *lex, byte c1, byte c2, byte c3) {
     return lex->chr0 == c1 || lex->chr0 == c2 || lex->chr0 == c3;
 }
 
+#if MICROPY_PY_FSTRINGS
+STATIC bool is_char_or4(mp_lexer_t *lex, byte c1, byte c2, byte c3, byte c4) {
+    return lex->chr0 == c1 || lex->chr0 == c2 || lex->chr0 == c3 || lex->chr0 == c4;
+}
+#endif
+
 STATIC bool is_char_following(mp_lexer_t *lex, byte c) {
     return lex->chr1 == c;
 }
@@ -105,7 +111,13 @@ STATIC bool is_following_odigit(mp_lexer_t *lex) {
 
 STATIC bool is_string_or_bytes(mp_lexer_t *lex) {
     return is_char_or(lex, '\'', '\"')
+           #if MICROPY_PY_FSTRINGS
+           || (is_char_or4(lex, 'r', 'u', 'b', 'f') && is_char_following_or(lex, '\'', '\"'))
+           || (((is_char_and(lex, 'r', 'f') || is_char_and(lex, 'f', 'r'))
+               && is_char_following_following_or(lex, '\'', '\"')))
+           #else
            || (is_char_or3(lex, 'r', 'u', 'b') && is_char_following_or(lex, '\'', '\"'))
+           #endif
            || ((is_char_and(lex, 'r', 'b') || is_char_and(lex, 'b', 'r'))
                && is_char_following_following_or(lex, '\'', '\"'));
 }
@@ -132,9 +144,35 @@ STATIC void next_char(mp_lexer_t *lex) {
         ++lex->column;
     }
 
+    // shift the input queue forward
     lex->chr0 = lex->chr1;
     lex->chr1 = lex->chr2;
-    lex->chr2 = lex->reader.readbyte(lex->reader.data);
+
+    // and add the next byte from either the fstring args or the reader
+    #if MICROPY_PY_FSTRINGS
+    if (lex->fstring_args_idx) {
+        // if there are saved chars, then we're currently injecting fstring args
+        if (lex->fstring_args_idx < lex->fstring_args.len) {
+            lex->chr2 = lex->fstring_args.buf[lex->fstring_args_idx++];
+        } else {
+            // no more fstring arg bytes
+            lex->chr2 = '\0';
+        }
+
+        if (lex->chr0 == '\0') {
+            // consumed all fstring data, restore saved input queue
+            lex->chr0 = lex->chr0_saved;
+            lex->chr1 = lex->chr1_saved;
+            lex->chr2 = lex->chr2_saved;
+            // stop consuming fstring arg data
+            vstr_reset(&lex->fstring_args);
+            lex->fstring_args_idx = 0;
+        }
+    } else
+    #endif
+    {
+        lex->chr2 = lex->reader.readbyte(lex->reader.data);
+    }
 
     if (lex->chr1 == '\r') {
         // CR is a new line, converted to LF
@@ -272,7 +310,7 @@ STATIC bool get_hex(mp_lexer_t *lex, size_t num_digits, mp_uint_t *result) {
     return true;
 }
 
-STATIC void parse_string_literal(mp_lexer_t *lex, bool is_raw) {
+STATIC void parse_string_literal(mp_lexer_t *lex, bool is_raw, bool is_fstring) {
     // get first quoting character
     char quote_char = '\'';
     if (is_char(lex, '\"')) {
@@ -293,12 +331,57 @@ STATIC void parse_string_literal(mp_lexer_t *lex, bool is_raw) {
     }
 
     size_t n_closing = 0;
+    #if MICROPY_PY_FSTRINGS
+    if (is_fstring) {
+        // assume there's going to be interpolation, so prep the injection data
+        // fstring_args_idx==0 && len(fstring_args)>0 means we're extracting the args.
+        // only when fstring_args_idx>0 will we consume the arg data
+        // note: lex->fstring_args will be empty already (it's reset when finished)
+        vstr_add_str(&lex->fstring_args, ".format(");
+    }
+    #endif
+
     while (!is_end(lex) && (num_quotes > 1 || !is_char(lex, '\n')) && n_closing < num_quotes) {
         if (is_char(lex, quote_char)) {
             n_closing += 1;
             vstr_add_char(&lex->vstr, CUR_CHAR(lex));
         } else {
             n_closing = 0;
+
+            #if MICROPY_PY_FSTRINGS
+            while (is_fstring && is_char(lex, '{')) {
+                next_char(lex);
+                if (is_char(lex, '{')) {
+                    // "{{" is passed through unchanged to be handled by str.format
+                    vstr_add_byte(&lex->vstr, '{');
+                    next_char(lex);
+                } else {
+                    // remember the start of this argument (if we need it for f'{a=}').
+                    size_t i = lex->fstring_args.len;
+                    // extract characters inside the { until we reach the
+                    // format specifier or closing }.
+                    // (MicroPython limitation) note: this is completely unaware of
+                    // Python syntax and will not handle any expression containing '}' or ':'.
+                    // e.g. f'{"}"}' or f'{foo({})}'.
+                    while (!is_end(lex) && !is_char_or(lex, ':', '}')) {
+                        // like the default case at the end of this function, stay 8-bit clean
+                        vstr_add_byte(&lex->fstring_args, CUR_CHAR(lex));
+                        next_char(lex);
+                    }
+                    if (lex->fstring_args.buf[lex->fstring_args.len - 1] == '=') {
+                        // if the last character of the arg was '=', then inject "arg=" before the '{'.
+                        // f'{a=}' --> 'a={}'.format(a)
+                        vstr_add_strn(&lex->vstr, lex->fstring_args.buf + i, lex->fstring_args.len - i);
+                        // remove the trailing '='
+                        lex->fstring_args.len--;
+                    }
+                    // comma-separate args
+                    vstr_add_byte(&lex->fstring_args, ',');
+                }
+                vstr_add_byte(&lex->vstr, '{');
+            }
+            #endif
+
             if (is_char(lex, '\\')) {
                 next_char(lex);
                 unichar c = CUR_CHAR(lex);
@@ -451,6 +534,23 @@ STATIC bool skip_whitespace(mp_lexer_t *lex, bool stop_at_newline) {
 }
 
 void mp_lexer_to_next(mp_lexer_t *lex) {
+    #if MICROPY_PY_FSTRINGS
+    if (lex->fstring_args.len && lex->fstring_args_idx == 0) {
+        // moving onto the next token means the literal string is complete.
+        // switch into injecting the format args.
+        vstr_add_byte(&lex->fstring_args, ')');
+        lex->chr0_saved = lex->chr0;
+        lex->chr1_saved = lex->chr1;
+        lex->chr2_saved = lex->chr2;
+        lex->chr0 = lex->fstring_args.buf[0];
+        lex->chr1 = lex->fstring_args.buf[1];
+        lex->chr2 = lex->fstring_args.buf[2];
+        // we've already extracted 3 chars, but setting this non-zero also
+        // means we'll start consuming the fstring data
+        lex->fstring_args_idx = 3;
+    }
+    #endif
+
     // start new token text
     vstr_reset(&lex->vstr);
 
@@ -506,6 +606,7 @@ void mp_lexer_to_next(mp_lexer_t *lex) {
         do {
             // parse type codes
             bool is_raw = false;
+            bool is_fstring = false;
             mp_token_kind_t kind = MP_TOKEN_STRING;
             int n_char = 0;
             if (is_char(lex, 'u')) {
@@ -524,7 +625,25 @@ void mp_lexer_to_next(mp_lexer_t *lex) {
                     kind = MP_TOKEN_BYTES;
                     n_char = 2;
                 }
+                #if MICROPY_PY_FSTRINGS
+                if (is_char_following(lex, 'f')) {
+                    // raw-f-strings unsupported, immediately return (invalid) token.
+                    lex->tok_kind = MP_TOKEN_FSTRING_RAW;
+                    break;
+                }
+                #endif
             }
+            #if MICROPY_PY_FSTRINGS
+            else if (is_char(lex, 'f')) {
+                if (is_char_following(lex, 'r')) {
+                    // raw-f-strings unsupported, immediately return (invalid) token.
+                    lex->tok_kind = MP_TOKEN_FSTRING_RAW;
+                    break;
+                }
+                n_char = 1;
+                is_fstring = true;
+            }
+            #endif
 
             // Set or check token kind
             if (lex->tok_kind == MP_TOKEN_END) {
@@ -543,7 +662,7 @@ void mp_lexer_to_next(mp_lexer_t *lex) {
             }
 
             // Parse the literal
-            parse_string_literal(lex, is_raw);
+            parse_string_literal(lex, is_raw, is_fstring);
 
             // Skip whitespace so we can check if there's another string following
             skip_whitespace(lex, true);
@@ -703,6 +822,9 @@ mp_lexer_t *mp_lexer_new(qstr src_name, mp_reader_t reader) {
     lex->num_indent_level = 1;
     lex->indent_level = m_new(uint16_t, lex->alloc_indent_level);
     vstr_init(&lex->vstr, 32);
+    #if MICROPY_PY_FSTRINGS
+    vstr_init(&lex->fstring_args, 0);
+    #endif
 
     // store sentinel for first indentation level
     lex->indent_level[0] = 0;
@@ -756,6 +878,9 @@ void mp_lexer_free(mp_lexer_t *lex) {
     if (lex) {
         lex->reader.close(lex->reader.data);
         vstr_clear(&lex->vstr);
+        #if MICROPY_PY_FSTRINGS
+        vstr_clear(&lex->fstring_args);
+        #endif
         m_del(uint16_t, lex->indent_level, lex->alloc_indent_level);
         m_del_obj(mp_lexer_t, lex);
     }
diff --git a/py/lexer.h b/py/lexer.h
index 91767a44b..e16b9a8ce 100644
--- a/py/lexer.h
+++ b/py/lexer.h
@@ -44,6 +44,10 @@ typedef enum _mp_token_kind_t {
     MP_TOKEN_INVALID,
     MP_TOKEN_DEDENT_MISMATCH,
     MP_TOKEN_LONELY_STRING_OPEN,
+    #if MICROPY_PY_FSTRINGS
+    MP_TOKEN_MALFORMED_FSTRING,
+    MP_TOKEN_FSTRING_RAW,
+    #endif
 
     MP_TOKEN_NEWLINE,
     MP_TOKEN_INDENT,
@@ -158,6 +162,9 @@ typedef struct _mp_lexer_t {
     mp_reader_t reader;         // stream source
 
     unichar chr0, chr1, chr2;   // current cached characters from source
+    #if MICROPY_PY_FSTRINGS
+    unichar chr0_saved, chr1_saved, chr2_saved; // current cached characters from alt source
+    #endif
 
     size_t line;                // current source line
     size_t column;              // current source column
@@ -173,6 +180,10 @@ typedef struct _mp_lexer_t {
     size_t tok_column;          // token source column
     mp_token_kind_t tok_kind;   // token kind
     vstr_t vstr;                // token data
+    #if MICROPY_PY_FSTRINGS
+    vstr_t fstring_args;        // extracted arguments to pass to .format()
+    size_t fstring_args_idx;    // how many bytes of fstring_args have been read
+    #endif
 } mp_lexer_t;
 
 mp_lexer_t *mp_lexer_new(qstr src_name, mp_reader_t reader);
diff --git a/py/makeversionhdr.py b/py/makeversionhdr.py
index 2f4bc9182..54b7fa9ab 100644
--- a/py/makeversionhdr.py
+++ b/py/makeversionhdr.py
@@ -23,7 +23,7 @@ def get_version_info_from_git():
     # Note: git describe doesn't work if no tag is available
     try:
         git_tag = subprocess.check_output(
-            ["git", "describe", "--dirty", "--always", "--match", "v[1-9].*"],
+            ["git", "describe", "--tags", "--dirty", "--always", "--match", "v[1-9].*"],
             stderr=subprocess.STDOUT,
             universal_newlines=True,
         ).strip()
diff --git a/py/misc.h b/py/misc.h
index 953809838..e1d27dc7b 100644
--- a/py/misc.h
+++ b/py/misc.h
@@ -55,6 +55,7 @@ typedef unsigned int uint;
 
 // Round-up integer division
 #define MP_CEIL_DIVIDE(a, b) (((a) + (b) - 1) / (b))
+#define MP_ROUND_DIVIDE(a, b) (((a) + (b) / 2) / (b))
 
 /** memory allocation ******************************************/
 
diff --git a/py/mkenv.mk b/py/mkenv.mk
index d54f0a0d3..2b247974b 100644
--- a/py/mkenv.mk
+++ b/py/mkenv.mk
@@ -55,11 +55,15 @@ AR = $(CROSS_COMPILE)ar
 
 MAKE_MANIFEST = $(PYTHON) $(TOP)/tools/makemanifest.py
 MAKE_FROZEN = $(PYTHON) $(TOP)/tools/make-frozen.py
-MPY_CROSS = $(TOP)/mpy-cross/mpy-cross
 MPY_TOOL = $(PYTHON) $(TOP)/tools/mpy-tool.py
 
 MPY_LIB_DIR = $(TOP)/../micropython-lib
 
+ifeq ($(MICROPY_MPYCROSS),)
+MICROPY_MPYCROSS = $(TOP)/mpy-cross/mpy-cross
+MICROPY_MPYCROSS_DEPENDENCY = $(MICROPY_MPYCROSS)
+endif
+
 all:
 .PHONY: all
 
diff --git a/py/mkrules.cmake b/py/mkrules.cmake
index 7589255b2..9d0801793 100644
--- a/py/mkrules.cmake
+++ b/py/mkrules.cmake
@@ -129,11 +129,27 @@ if(MICROPY_FROZEN_MANIFEST)
         set(MICROPY_LIB_DIR ${MICROPY_DIR}/../micropython-lib)
     endif()
 
+    # If MICROPY_MPYCROSS is not explicitly defined in the environment (which
+    # is what makemanifest.py will use) then create an mpy-cross dependency
+    # to automatically build mpy-cross if needed.
+    set(MICROPY_MPYCROSS $ENV{MICROPY_MPYCROSS})
+    if(NOT MICROPY_MPYCROSS)
+        set(MICROPY_MPYCROSS_DEPENDENCY ${MICROPY_DIR}/mpy-cross/mpy-cross)
+        if(NOT MICROPY_MAKE_EXECUTABLE)
+            set(MICROPY_MAKE_EXECUTABLE make)
+        endif()
+        add_custom_command(
+            OUTPUT ${MICROPY_MPYCROSS_DEPENDENCY}
+            COMMAND ${MICROPY_MAKE_EXECUTABLE} -C ${MICROPY_DIR}/mpy-cross
+        )
+    endif()
+
     add_custom_command(
         OUTPUT ${MICROPY_FROZEN_CONTENT}
         COMMAND ${Python3_EXECUTABLE} ${MICROPY_DIR}/tools/makemanifest.py -o ${MICROPY_FROZEN_CONTENT} -v "MPY_DIR=${MICROPY_DIR}" -v "MPY_LIB_DIR=${MICROPY_LIB_DIR}" -v "PORT_DIR=${MICROPY_PORT_DIR}" -v "BOARD_DIR=${MICROPY_BOARD_DIR}" -b "${CMAKE_BINARY_DIR}" -f${MICROPY_CROSS_FLAGS} ${MICROPY_FROZEN_MANIFEST}
         DEPENDS MICROPY_FORCE_BUILD
             ${MICROPY_QSTRDEFS_GENERATED}
+            ${MICROPY_MPYCROSS_DEPENDENCY}
         VERBATIM
     )
 endif()
diff --git a/py/mkrules.mk b/py/mkrules.mk
index 038a49329..d0c0a53c2 100644
--- a/py/mkrules.mk
+++ b/py/mkrules.mk
@@ -136,9 +136,15 @@ $(OBJ_DIRS):
 $(HEADER_BUILD):
 	$(MKDIR) -p $@
 
+ifneq ($(MICROPY_MPYCROSS_DEPENDENCY),)
+# to automatically build mpy-cross, if needed
+$(MICROPY_MPYCROSS_DEPENDENCY):
+	$(MAKE) -C $(dir $@)
+endif
+
 ifneq ($(FROZEN_MANIFEST),)
 # to build frozen_content.c from a manifest
-$(BUILD)/frozen_content.c: FORCE $(BUILD)/genhdr/qstrdefs.generated.h
+$(BUILD)/frozen_content.c: FORCE $(BUILD)/genhdr/qstrdefs.generated.h | $(MICROPY_MPYCROSS_DEPENDENCY)
 	$(Q)$(MAKE_MANIFEST) -o $@ -v "MPY_DIR=$(TOP)" -v "MPY_LIB_DIR=$(MPY_LIB_DIR)" -v "PORT_DIR=$(shell pwd)" -v "BOARD_DIR=$(BOARD_DIR)" -b "$(BUILD)" $(if $(MPY_CROSS_FLAGS),-f"$(MPY_CROSS_FLAGS)",) --mpy-tool-flags="$(MPY_TOOL_FLAGS)" $(FROZEN_MANIFEST)
 
 ifneq ($(FROZEN_DIR),)
@@ -164,10 +170,10 @@ FROZEN_MPY_PY_FILES := $(shell find -L $(FROZEN_MPY_DIR) -type f -name '*.py' |
 FROZEN_MPY_MPY_FILES := $(addprefix $(BUILD)/frozen_mpy/,$(FROZEN_MPY_PY_FILES:.py=.mpy))
 
 # to build .mpy files from .py files
-$(BUILD)/frozen_mpy/%.mpy: $(FROZEN_MPY_DIR)/%.py
+$(BUILD)/frozen_mpy/%.mpy: $(FROZEN_MPY_DIR)/%.py | $(MICROPY_MPYCROSS_DEPENDENCY)
 	@$(ECHO) "MPY $<"
 	$(Q)$(MKDIR) -p $(dir $@)
-	$(Q)$(MPY_CROSS) -o $@ -s $(<:$(FROZEN_MPY_DIR)/%=%) $(MPY_CROSS_FLAGS) $<
+	$(Q)$(MICROPY_MPYCROSS) -o $@ -s $(<:$(FROZEN_MPY_DIR)/%=%) $(MPY_CROSS_FLAGS) $<
 
 # to build frozen_mpy.c from all .mpy files
 $(BUILD)/frozen_mpy.c: $(FROZEN_MPY_MPY_FILES) $(BUILD)/genhdr/qstrdefs.generated.h
@@ -178,6 +184,13 @@ endif
 ifneq ($(PROG),)
 # Build a standalone executable (unix does this)
 
+# The executable should have an .exe extension for builds targetting 'pure'
+# Windows, i.e. msvc or mingw builds, but not when using msys or cygwin's gcc.
+COMPILER_TARGET := $(shell $(CC) -dumpmachine)
+ifneq (,$(findstring mingw,$(COMPILER_TARGET)))
+PROG := $(PROG).exe
+endif
+
 all: $(PROG)
 
 $(PROG): $(OBJ)
@@ -186,9 +199,9 @@ $(PROG): $(OBJ)
 # we may want to compile using Thumb, but link with non-Thumb libc.
 	$(Q)$(CC) -o $@ $^ $(LIB) $(LDFLAGS)
 ifndef DEBUG
-	$(Q)$(STRIP) $(STRIPFLAGS_EXTRA) $(PROG)
+	$(Q)$(STRIP) $(STRIPFLAGS_EXTRA) $@
 endif
-	$(Q)$(SIZE) $$(find $(BUILD) -path "$(BUILD)/build/frozen*.o") $(PROG)
+	$(Q)$(SIZE) $$(find $(BUILD) -path "$(BUILD)/build/frozen*.o") $@
 
 clean: clean-prog
 clean-prog:
@@ -201,6 +214,7 @@ endif
 submodules:
 	$(ECHO) "Updating submodules: $(GIT_SUBMODULES)"
 ifneq ($(GIT_SUBMODULES),)
+	$(Q)git submodule sync $(addprefix $(TOP)/,$(GIT_SUBMODULES))
 	$(Q)git submodule update --init $(addprefix $(TOP)/,$(GIT_SUBMODULES))
 endif
 .PHONY: submodules
diff --git a/py/modbuiltins.c b/py/modbuiltins.c
index ac41942b9..a7e49a1ed 100644
--- a/py/modbuiltins.c
+++ b/py/modbuiltins.c
@@ -230,7 +230,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin_hex_obj, mp_builtin_hex);
 #if MICROPY_PY_BUILTINS_INPUT
 
 #include "py/mphal.h"
-#include "lib/mp-readline/readline.h"
+#include "shared/readline/readline.h"
 
 // A port can define mp_hal_readline if they want to use a custom function here
 #ifndef mp_hal_readline
@@ -322,7 +322,7 @@ STATIC mp_obj_t mp_builtin_next(size_t n_args, const mp_obj_t *args) {
     if (n_args == 1) {
         mp_obj_t ret = mp_iternext_allow_raise(args[0]);
         if (ret == MP_OBJ_STOP_ITERATION) {
-            mp_raise_type(&mp_type_StopIteration);
+            mp_raise_StopIteration(MP_STATE_THREAD(stop_iteration_arg));
         } else {
             return ret;
         }
@@ -336,7 +336,7 @@ MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin_next_obj, 1, 2, mp_builtin_next);
 STATIC mp_obj_t mp_builtin_next(mp_obj_t o) {
     mp_obj_t ret = mp_iternext_allow_raise(o);
     if (ret == MP_OBJ_STOP_ITERATION) {
-        mp_raise_type(&mp_type_StopIteration);
+        mp_raise_StopIteration(MP_STATE_THREAD(stop_iteration_arg));
     } else {
         return ret;
     }
diff --git a/py/modsys.c b/py/modsys.c
index 586b13e74..64349f3c3 100644
--- a/py/modsys.c
+++ b/py/modsys.c
@@ -110,13 +110,11 @@ STATIC const MP_DEFINE_STR_OBJ(mp_sys_platform_obj, MICROPY_PY_SYS_PLATFORM);
 
 // exit([retval]): raise SystemExit, with optional argument given to the exception
 STATIC mp_obj_t mp_sys_exit(size_t n_args, const mp_obj_t *args) {
-    mp_obj_t exc;
     if (n_args == 0) {
-        exc = mp_obj_new_exception(&mp_type_SystemExit);
+        mp_raise_type(&mp_type_SystemExit);
     } else {
-        exc = mp_obj_new_exception_arg1(&mp_type_SystemExit, args[0]);
+        mp_raise_type_arg(&mp_type_SystemExit, args[0]);
     }
-    nlr_raise(exc);
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_sys_exit_obj, 0, 1, mp_sys_exit);
 
diff --git a/py/mpconfig.h b/py/mpconfig.h
index d40637dfa..71440da39 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -28,7 +28,7 @@
 
 // Current version of MicroPython
 #define MICROPY_VERSION_MAJOR 1
-#define MICROPY_VERSION_MINOR 16
+#define MICROPY_VERSION_MINOR 17
 #define MICROPY_VERSION_MICRO 0
 
 // Combined version as a 32-bit number for convenience
@@ -483,7 +483,8 @@
 /* Optimisations                                                             */
 
 // Whether to use computed gotos in the VM, or a switch
-// Computed gotos are roughly 10% faster, and increase VM code size by a little
+// Computed gotos are roughly 10% faster, and increase VM code size by a little,
+// e.g. ~1kiB on Cortex M4.
 // Note: enabling this will use the gcc-specific extensions of ranged designated
 // initialisers and addresses of labels, which are not part of the C99 standard.
 #ifndef MICROPY_OPT_COMPUTED_GOTO
@@ -875,6 +876,11 @@ typedef double mp_float_t;
 #define MICROPY_PY_ASYNC_AWAIT (1)
 #endif
 
+// Support for literal string interpolation, f-strings (see PEP 498, Python 3.6+)
+#ifndef MICROPY_PY_FSTRINGS
+#define MICROPY_PY_FSTRINGS (0)
+#endif
+
 // Support for assignment expressions with := (see PEP 572, Python 3.8+)
 #ifndef MICROPY_PY_ASSIGN_EXPR
 #define MICROPY_PY_ASSIGN_EXPR (1)
@@ -1063,7 +1069,7 @@ typedef double mp_float_t;
 #endif
 
 // Whether to provide the built-in input() function. The implementation of this
-// uses mp-readline, so can only be enabled if the port uses this readline.
+// uses shared/readline, so can only be enabled if the port uses this readline.
 #ifndef MICROPY_PY_BUILTINS_INPUT
 #define MICROPY_PY_BUILTINS_INPUT (0)
 #endif
@@ -1316,6 +1322,13 @@ typedef double mp_float_t;
 #define MICROPY_PY_USELECT (0)
 #endif
 
+// Whether to enable the select() function in the "uselect" module (baremetal
+// implementation). This is present for compatibility but can be disabled to
+// save space.
+#ifndef MICROPY_PY_USELECT_SELECT
+#define MICROPY_PY_USELECT_SELECT (1)
+#endif
+
 // Whether to provide "utime" module functions implementation
 // in terms of mp_hal_* functions.
 #ifndef MICROPY_PY_UTIME_MP_HAL
@@ -1373,6 +1386,11 @@ typedef double mp_float_t;
 #define MICROPY_PY_UJSON (0)
 #endif
 
+// Whether to support the "separators" argument to dump, dumps
+#ifndef MICROPY_PY_UJSON_SEPARATORS
+#define MICROPY_PY_UJSON_SEPARATORS (1)
+#endif
+
 #ifndef MICROPY_PY_URE
 #define MICROPY_PY_URE (0)
 #endif
@@ -1453,6 +1471,11 @@ typedef double mp_float_t;
 #define MICROPY_PY_MACHINE (0)
 #endif
 
+// Whether to include: bitstream
+#ifndef MICROPY_PY_MACHINE_BITSTREAM
+#define MICROPY_PY_MACHINE_BITSTREAM (0)
+#endif
+
 // Whether to include: time_pulse_us
 #ifndef MICROPY_PY_MACHINE_PULSE
 #define MICROPY_PY_MACHINE_PULSE (0)
diff --git a/py/mpprint.h b/py/mpprint.h
index aef9015de..0dff9a770 100644
--- a/py/mpprint.h
+++ b/py/mpprint.h
@@ -52,6 +52,14 @@ typedef struct _mp_print_t {
     mp_print_strn_t print_strn;
 } mp_print_t;
 
+typedef struct _mp_print_ext_t {
+    mp_print_t base;
+    const char *item_separator;
+    const char *key_separator;
+}mp_print_ext_t;
+
+#define MP_PRINT_GET_EXT(print) ((mp_print_ext_t *)print)
+
 // All (non-debug) prints go through one of the two interfaces below.
 // 1) Wrapper for platform print function, which wraps MP_PLAT_PRINT_STRN.
 extern const mp_print_t mp_plat_print;
diff --git a/py/mpstate.h b/py/mpstate.h
index e42d13fb2..07335bae4 100644
--- a/py/mpstate.h
+++ b/py/mpstate.h
@@ -266,6 +266,9 @@ typedef struct _mp_state_thread_t {
     // pending exception object (MP_OBJ_NULL if not pending)
     volatile mp_obj_t mp_pending_exception;
 
+    // If MP_OBJ_STOP_ITERATION is propagated then this holds its argument.
+    mp_obj_t stop_iteration_arg;
+
     #if MICROPY_PY_SYS_SETTRACE
     mp_obj_t prof_trace_callback;
     bool prof_callback_is_executing;
diff --git a/py/obj.h b/py/obj.h
index 86e5d8312..11918ba17 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -739,7 +739,6 @@ mp_obj_t mp_obj_new_int_from_float(mp_float_t val);
 mp_obj_t mp_obj_new_complex(mp_float_t real, mp_float_t imag);
 #endif
 mp_obj_t mp_obj_new_exception(const mp_obj_type_t *exc_type);
-mp_obj_t mp_obj_new_exception_arg1(const mp_obj_type_t *exc_type, mp_obj_t arg);
 mp_obj_t mp_obj_new_exception_args(const mp_obj_type_t *exc_type, size_t n_args, const mp_obj_t *args);
 #if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_NONE
 #define mp_obj_new_exception_msg(exc_type, msg) mp_obj_new_exception(exc_type)
@@ -780,9 +779,11 @@ bool mp_obj_is_callable(mp_obj_t o_in);
 mp_obj_t mp_obj_equal_not_equal(mp_binary_op_t op, mp_obj_t o1, mp_obj_t o2);
 bool mp_obj_equal(mp_obj_t o1, mp_obj_t o2);
 
+// returns true if o is bool, small int or long int
 static inline bool mp_obj_is_integer(mp_const_obj_t o) {
     return mp_obj_is_int(o) || mp_obj_is_bool(o);
-}                                                                                                        // returns true if o is bool, small int or long int
+}
+
 mp_int_t mp_obj_get_int(mp_const_obj_t arg);
 mp_int_t mp_obj_get_int_truncated(mp_const_obj_t arg);
 bool mp_obj_get_int_maybe(mp_const_obj_t arg, mp_int_t *value);
@@ -825,6 +826,10 @@ mp_obj_t mp_obj_exception_get_value(mp_obj_t self_in);
 mp_obj_t mp_obj_exception_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
 mp_obj_t mp_alloc_emergency_exception_buf(mp_obj_t size_in);
 void mp_init_emergency_exception_buf(void);
+static inline mp_obj_t mp_obj_new_exception_arg1(const mp_obj_type_t *exc_type, mp_obj_t arg) {
+    assert(exc_type->make_new == mp_obj_exception_make_new);
+    return mp_obj_exception_make_new(exc_type, 1, 0, &arg);
+}
 
 // str
 bool mp_obj_str_equal(mp_obj_t s1, mp_obj_t s2);
diff --git a/py/objdict.c b/py/objdict.c
index aea5952d3..ed4376aa4 100644
--- a/py/objdict.c
+++ b/py/objdict.c
@@ -69,8 +69,15 @@ STATIC mp_map_elem_t *dict_iter_next(mp_obj_dict_t *dict, size_t *cur) {
 STATIC void dict_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
     mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
     bool first = true;
+    const char *item_separator = ", ";
+    const char *key_separator = ": ";
     if (!(MICROPY_PY_UJSON && kind == PRINT_JSON)) {
         kind = PRINT_REPR;
+    } else {
+        #if MICROPY_PY_UJSON_SEPARATORS
+        item_separator = MP_PRINT_GET_EXT(print)->item_separator;
+        key_separator = MP_PRINT_GET_EXT(print)->key_separator;
+        #endif
     }
     if (MICROPY_PY_COLLECTIONS_ORDEREDDICT && self->base.type != &mp_type_dict && kind != PRINT_JSON) {
         mp_printf(print, "%q(", self->base.type->name);
@@ -80,7 +87,7 @@ STATIC void dict_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_
     mp_map_elem_t *next = NULL;
     while ((next = dict_iter_next(self, &cur)) != NULL) {
         if (!first) {
-            mp_print_str(print, ", ");
+            mp_print_str(print, item_separator);
         }
         first = false;
         bool add_quote = MICROPY_PY_UJSON && kind == PRINT_JSON && !mp_obj_is_str_or_bytes(next->key);
@@ -91,7 +98,7 @@ STATIC void dict_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_
         if (add_quote) {
             mp_print_str(print, "\"");
         }
-        mp_print_str(print, ": ");
+        mp_print_str(print, key_separator);
         mp_obj_print_helper(print, next->value, kind);
     }
     mp_print_str(print, "}");
@@ -190,7 +197,7 @@ mp_obj_t mp_obj_dict_get(mp_obj_t self_in, mp_obj_t index) {
     mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
     mp_map_elem_t *elem = mp_map_lookup(&self->map, index, MP_MAP_LOOKUP);
     if (elem == NULL) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, index));
+        mp_raise_type_arg(&mp_type_KeyError, index);
     } else {
         return elem->value;
     }
@@ -206,7 +213,7 @@ STATIC mp_obj_t dict_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
         mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
         mp_map_elem_t *elem = mp_map_lookup(&self->map, index, MP_MAP_LOOKUP);
         if (elem == NULL) {
-            nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, index));
+            mp_raise_type_arg(&mp_type_KeyError, index);
         } else {
             return elem->value;
         }
@@ -295,7 +302,7 @@ STATIC mp_obj_t dict_get_helper(size_t n_args, const mp_obj_t *args, mp_map_look
     if (elem == NULL || elem->value == MP_OBJ_NULL) {
         if (n_args == 2) {
             if (lookup_kind == MP_MAP_LOOKUP_REMOVE_IF_FOUND) {
-                nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, args[1]));
+                mp_raise_type_arg(&mp_type_KeyError, args[1]);
             } else {
                 value = mp_const_none;
             }
diff --git a/py/objexcept.c b/py/objexcept.c
index a10bd2c18..7a86c3647 100644
--- a/py/objexcept.c
+++ b/py/objexcept.c
@@ -111,6 +111,15 @@ mp_obj_t mp_alloc_emergency_exception_buf(mp_obj_t size_in) {
 #endif
 #endif  // MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
 
+STATIC mp_obj_exception_t *get_native_exception(mp_obj_t self_in) {
+    assert(mp_obj_is_exception_instance(self_in));
+    if (mp_obj_is_native_exception_instance(self_in)) {
+        return MP_OBJ_TO_PTR(self_in);
+    } else {
+        return MP_OBJ_TO_PTR(((mp_obj_instance_t *)MP_OBJ_TO_PTR(self_in))->subobj[0]);
+    }
+}
+
 STATIC void decompress_error_text_maybe(mp_obj_exception_t *o) {
     #if MICROPY_ROM_TEXT_COMPRESSION
     if (o->args->len == 1 && mp_obj_is_type(o->args->items[0], &mp_type_str)) {
@@ -240,7 +249,7 @@ mp_obj_t mp_obj_exception_make_new(const mp_obj_type_t *type, size_t n_args, siz
 
 // Get exception "value" - that is, first argument, or None
 mp_obj_t mp_obj_exception_get_value(mp_obj_t self_in) {
-    mp_obj_exception_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_obj_exception_t *self = get_native_exception(self_in);
     if (self->args->len == 0) {
         return mp_const_none;
     } else {
@@ -369,12 +378,6 @@ mp_obj_t mp_obj_new_exception(const mp_obj_type_t *exc_type) {
     return mp_obj_exception_make_new(exc_type, 0, 0, NULL);
 }
 
-// "Optimized" version for common(?) case of having 1 exception arg
-mp_obj_t mp_obj_new_exception_arg1(const mp_obj_type_t *exc_type, mp_obj_t arg) {
-    assert(exc_type->make_new == mp_obj_exception_make_new);
-    return mp_obj_exception_make_new(exc_type, 1, 0, &arg);
-}
-
 mp_obj_t mp_obj_new_exception_args(const mp_obj_type_t *exc_type, size_t n_args, const mp_obj_t *args) {
     assert(exc_type->make_new == mp_obj_exception_make_new);
     return mp_obj_exception_make_new(exc_type, n_args, 0, args);
@@ -559,25 +562,15 @@ bool mp_obj_exception_match(mp_obj_t exc, mp_const_obj_t exc_type) {
 
 // traceback handling functions
 
-#define GET_NATIVE_EXCEPTION(self, self_in) \
-    /* make sure self_in is an exception instance */ \
-    assert(mp_obj_is_exception_instance(self_in)); \
-    mp_obj_exception_t *self; \
-    if (mp_obj_is_native_exception_instance(self_in)) { \
-        self = MP_OBJ_TO_PTR(self_in); \
-    } else { \
-        self = MP_OBJ_TO_PTR(((mp_obj_instance_t *)MP_OBJ_TO_PTR(self_in))->subobj[0]); \
-    }
-
 void mp_obj_exception_clear_traceback(mp_obj_t self_in) {
-    GET_NATIVE_EXCEPTION(self, self_in);
+    mp_obj_exception_t *self = get_native_exception(self_in);
     // just set the traceback to the null object
     // we don't want to call any memory management functions here
     self->traceback_data = NULL;
 }
 
 void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, size_t line, qstr block) {
-    GET_NATIVE_EXCEPTION(self, self_in);
+    mp_obj_exception_t *self = get_native_exception(self_in);
 
     // append this traceback info to traceback data
     // if memory allocation fails (eg because gc is locked), just return
@@ -630,7 +623,7 @@ void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, size_t line, qs
 }
 
 void mp_obj_exception_get_traceback(mp_obj_t self_in, size_t *n, size_t **values) {
-    GET_NATIVE_EXCEPTION(self, self_in);
+    mp_obj_exception_t *self = get_native_exception(self_in);
 
     if (self->traceback_data == NULL) {
         *n = 0;
diff --git a/py/objgenerator.c b/py/objgenerator.c
index 543685fac..784310092 100644
--- a/py/objgenerator.c
+++ b/py/objgenerator.c
@@ -152,8 +152,9 @@ mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_
     mp_check_self(mp_obj_is_type(self_in, &mp_type_gen_instance));
     mp_obj_gen_instance_t *self = MP_OBJ_TO_PTR(self_in);
     if (self->code_state.ip == 0) {
-        // Trying to resume already stopped generator
-        *ret_val = MP_OBJ_STOP_ITERATION;
+        // Trying to resume an already stopped generator.
+        // This is an optimised "raise StopIteration(None)".
+        *ret_val = mp_const_none;
         return MP_VM_RETURN_NORMAL;
     }
 
@@ -212,6 +213,7 @@ mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_
             // subsequent next() may re-execute statements after last yield
             // again and again, leading to side effects.
             self->code_state.ip = 0;
+            // This is an optimised "raise StopIteration(*ret_val)".
             *ret_val = *self->code_state.sp;
             break;
 
@@ -236,16 +238,20 @@ mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_
     return ret_kind;
 }
 
-STATIC mp_obj_t gen_resume_and_raise(mp_obj_t self_in, mp_obj_t send_value, mp_obj_t throw_value) {
+STATIC mp_obj_t gen_resume_and_raise(mp_obj_t self_in, mp_obj_t send_value, mp_obj_t throw_value, bool raise_stop_iteration) {
     mp_obj_t ret;
     switch (mp_obj_gen_resume(self_in, send_value, throw_value, &ret)) {
         case MP_VM_RETURN_NORMAL:
         default:
-            // Optimize return w/o value in case generator is used in for loop
-            if (ret == mp_const_none || ret == MP_OBJ_STOP_ITERATION) {
-                return MP_OBJ_STOP_ITERATION;
+            // A normal return is a StopIteration, either raise it or return
+            // MP_OBJ_STOP_ITERATION as an optimisation.
+            if (ret == mp_const_none) {
+                ret = MP_OBJ_NULL;
+            }
+            if (raise_stop_iteration) {
+                mp_raise_StopIteration(ret);
             } else {
-                nlr_raise(mp_obj_new_exception_arg1(&mp_type_StopIteration, ret));
+                return mp_make_stop_iteration(ret);
             }
 
         case MP_VM_RETURN_YIELD:
@@ -257,16 +263,11 @@ STATIC mp_obj_t gen_resume_and_raise(mp_obj_t self_in, mp_obj_t send_value, mp_o
 }
 
 STATIC mp_obj_t gen_instance_iternext(mp_obj_t self_in) {
-    return gen_resume_and_raise(self_in, mp_const_none, MP_OBJ_NULL);
+    return gen_resume_and_raise(self_in, mp_const_none, MP_OBJ_NULL, false);
 }
 
 STATIC mp_obj_t gen_instance_send(mp_obj_t self_in, mp_obj_t send_value) {
-    mp_obj_t ret = gen_resume_and_raise(self_in, send_value, MP_OBJ_NULL);
-    if (ret == MP_OBJ_STOP_ITERATION) {
-        mp_raise_type(&mp_type_StopIteration);
-    } else {
-        return ret;
-    }
+    return gen_resume_and_raise(self_in, send_value, MP_OBJ_NULL, true);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(gen_instance_send_obj, gen_instance_send);
 
@@ -288,12 +289,7 @@ STATIC mp_obj_t gen_instance_throw(size_t n_args, const mp_obj_t *args) {
         exc = args[2];
     }
 
-    mp_obj_t ret = gen_resume_and_raise(args[0], mp_const_none, exc);
-    if (ret == MP_OBJ_STOP_ITERATION) {
-        mp_raise_type(&mp_type_StopIteration);
-    } else {
-        return ret;
-    }
+    return gen_resume_and_raise(args[0], mp_const_none, exc, true);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(gen_instance_throw_obj, 2, 4, gen_instance_throw);
 
diff --git a/py/objgetitemiter.c b/py/objgetitemiter.c
index 2670314ab..31ed4a922 100644
--- a/py/objgetitemiter.c
+++ b/py/objgetitemiter.c
@@ -48,7 +48,6 @@ STATIC mp_obj_t it_iternext(mp_obj_t self_in) {
         // an exception was raised
         mp_obj_type_t *t = (mp_obj_type_t *)((mp_obj_base_t *)nlr.ret_val)->type;
         if (t == &mp_type_StopIteration || t == &mp_type_IndexError) {
-            // return MP_OBJ_STOP_ITERATION instead of raising
             return MP_OBJ_STOP_ITERATION;
         } else {
             // re-raise exception
diff --git a/py/objlist.c b/py/objlist.c
index 8c989facc..f431e273d 100644
--- a/py/objlist.c
+++ b/py/objlist.c
@@ -44,13 +44,18 @@ STATIC mp_obj_t list_pop(size_t n_args, const mp_obj_t *args);
 
 STATIC void list_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
     mp_obj_list_t *o = MP_OBJ_TO_PTR(o_in);
+    const char *item_separator = ", ";
     if (!(MICROPY_PY_UJSON && kind == PRINT_JSON)) {
         kind = PRINT_REPR;
+    } else {
+        #if MICROPY_PY_UJSON_SEPARATORS
+        item_separator = MP_PRINT_GET_EXT(print)->item_separator;
+        #endif
     }
     mp_print_str(print, "[");
     for (size_t i = 0; i < o->len; i++) {
         if (i > 0) {
-            mp_print_str(print, ", ");
+            mp_print_str(print, item_separator);
         }
         mp_obj_print_helper(print, o->items[i], kind);
     }
diff --git a/py/objset.c b/py/objset.c
index dac9b1138..d2508bfbf 100644
--- a/py/objset.c
+++ b/py/objset.c
@@ -372,7 +372,7 @@ STATIC mp_obj_t set_remove(mp_obj_t self_in, mp_obj_t item) {
     check_set(self_in);
     mp_obj_set_t *self = MP_OBJ_TO_PTR(self_in);
     if (mp_set_lookup(&self->set, item, MP_MAP_LOOKUP_REMOVE_IF_FOUND) == MP_OBJ_NULL) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, item));
+        mp_raise_type_arg(&mp_type_KeyError, item);
     }
     return mp_const_none;
 }
diff --git a/py/objstr.c b/py/objstr.c
index 98657bd21..7d7f0e1df 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -1081,7 +1081,7 @@ STATIC vstr_t mp_obj_str_format_helper(const char *str, const char *top, int *ar
                 field_name = lookup;
                 mp_map_elem_t *key_elem = mp_map_lookup(kwargs, field_q, MP_MAP_LOOKUP);
                 if (key_elem == NULL) {
-                    nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, field_q));
+                    mp_raise_type_arg(&mp_type_KeyError, field_q);
                 }
                 arg = key_elem->value;
             }
diff --git a/py/objtuple.c b/py/objtuple.c
index 07a560ac0..67d7bc356 100644
--- a/py/objtuple.c
+++ b/py/objtuple.c
@@ -39,15 +39,19 @@
 
 void mp_obj_tuple_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
     mp_obj_tuple_t *o = MP_OBJ_TO_PTR(o_in);
+    const char *item_separator = ", ";
     if (MICROPY_PY_UJSON && kind == PRINT_JSON) {
         mp_print_str(print, "[");
+        #if MICROPY_PY_UJSON_SEPARATORS
+        item_separator = MP_PRINT_GET_EXT(print)->item_separator;
+        #endif
     } else {
         mp_print_str(print, "(");
         kind = PRINT_REPR;
     }
     for (size_t i = 0; i < o->len; i++) {
         if (i > 0) {
-            mp_print_str(print, ", ");
+            mp_print_str(print, item_separator);
         }
         mp_obj_print_helper(print, o->items[i], kind);
     }
diff --git a/py/parse.c b/py/parse.c
index da2f5e796..ae3fa8ea6 100644
--- a/py/parse.c
+++ b/py/parse.c
@@ -1152,6 +1152,14 @@ mp_parse_tree_t mp_parse(mp_lexer_t *lex, mp_parse_input_kind_t input_kind) {
         } else if (lex->tok_kind == MP_TOKEN_DEDENT_MISMATCH) {
             exc = mp_obj_new_exception_msg(&mp_type_IndentationError,
                 MP_ERROR_TEXT("unindent doesn't match any outer indent level"));
+        #if MICROPY_PY_FSTRINGS
+        } else if (lex->tok_kind == MP_TOKEN_MALFORMED_FSTRING) {
+            exc = mp_obj_new_exception_msg(&mp_type_SyntaxError,
+                MP_ERROR_TEXT("malformed f-string"));
+        } else if (lex->tok_kind == MP_TOKEN_FSTRING_RAW) {
+            exc = mp_obj_new_exception_msg(&mp_type_SyntaxError,
+                MP_ERROR_TEXT("raw f-strings are not supported"));
+        #endif
         } else {
             exc = mp_obj_new_exception_msg(&mp_type_SyntaxError,
                 MP_ERROR_TEXT("invalid syntax"));
diff --git a/py/py.mk b/py/py.mk
index ee3f28685..787cc8ee8 100644
--- a/py/py.mk
+++ b/py/py.mk
@@ -233,6 +233,7 @@ PY_EXTMOD_O_BASENAME = \
 	extmod/moducryptolib.o \
 	extmod/modubinascii.o \
 	extmod/virtpin.o \
+	extmod/machine_bitstream.o \
 	extmod/machine_mem.o \
 	extmod/machine_pinbase.o \
 	extmod/machine_signal.o \
@@ -258,8 +259,8 @@ PY_EXTMOD_O_BASENAME = \
 	extmod/vfs_lfs.o \
 	extmod/utime_mphal.o \
 	extmod/uos_dupterm.o \
-	lib/embed/abort_.o \
-	lib/utils/printf.o \
+	shared/libc/abort_.o \
+	shared/libc/printf.o \
 
 # prepend the build destination prefix to the py object files
 PY_CORE_O = $(addprefix $(BUILD)/, $(PY_CORE_O_BASENAME))
@@ -321,7 +322,7 @@ $(HEADER_BUILD)/moduledefs.h: $(SRC_QSTR) $(QSTR_GLOBAL_DEPENDENCIES) | $(HEADER
 # Standard C functions like memset need to be compiled with special flags so
 # the compiler does not optimise these functions in terms of themselves.
 CFLAGS_BUILTIN ?= -ffreestanding -fno-builtin -fno-lto
-$(BUILD)/lib/libc/string0.o: CFLAGS += $(CFLAGS_BUILTIN)
+$(BUILD)/shared/libc/string0.o: CFLAGS += $(CFLAGS_BUILTIN)
 
 # Force nlr code to always be compiled with space-saving optimisation so
 # that the function preludes are of a minimal and predictable form.
diff --git a/py/pystack.c b/py/pystack.c
index f7323fd74..ea5f0d9d1 100644
--- a/py/pystack.c
+++ b/py/pystack.c
@@ -43,8 +43,7 @@ void *mp_pystack_alloc(size_t n_bytes) {
     #endif
     if (MP_STATE_THREAD(pystack_cur) + n_bytes > MP_STATE_THREAD(pystack_end)) {
         // out of memory in the pystack
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_RuntimeError,
-            MP_OBJ_NEW_QSTR(MP_QSTR_pystack_space_exhausted)));
+        mp_raise_type_arg(&mp_type_RuntimeError, MP_OBJ_NEW_QSTR(MP_QSTR_pystack_space_exhausted));
     }
     void *ptr = MP_STATE_THREAD(pystack_cur);
     MP_STATE_THREAD(pystack_cur) += n_bytes;
diff --git a/py/runtime.c b/py/runtime.c
index 261670d4f..27e5bc13e 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -284,6 +284,12 @@ mp_obj_t mp_unary_op(mp_unary_op_t op, mp_obj_t arg) {
                 return result;
             }
         }
+        if (op == MP_UNARY_OP_BOOL) {
+            // Type doesn't have unary_op (or didn't handle MP_UNARY_OP_BOOL),
+            // so is implicitly True as this code path is impossible to reach
+            // if arg==mp_const_none.
+            return mp_const_true;
+        }
         // With MP_UNARY_OP_INT, mp_unary_op() becomes a fallback for mp_obj_get_int().
         // In this case provide a more focused error message to not confuse, e.g. chr(1.0)
         #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
@@ -1217,6 +1223,7 @@ mp_obj_t mp_getiter(mp_obj_t o_in, mp_obj_iter_buf_t *iter_buf) {
 mp_obj_t mp_iternext_allow_raise(mp_obj_t o_in) {
     const mp_obj_type_t *type = mp_obj_get_type(o_in);
     if (type->iternext != NULL) {
+        MP_STATE_THREAD(stop_iteration_arg) = MP_OBJ_NULL;
         return type->iternext(o_in);
     } else {
         // check for __next__ method
@@ -1242,6 +1249,7 @@ mp_obj_t mp_iternext(mp_obj_t o_in) {
     MP_STACK_CHECK(); // enumerate, filter, map and zip can recursively call mp_iternext
     const mp_obj_type_t *type = mp_obj_get_type(o_in);
     if (type->iternext != NULL) {
+        MP_STATE_THREAD(stop_iteration_arg) = MP_OBJ_NULL;
         return type->iternext(o_in);
     } else {
         // check for __next__ method
@@ -1256,7 +1264,7 @@ mp_obj_t mp_iternext(mp_obj_t o_in) {
                 return ret;
             } else {
                 if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(((mp_obj_base_t *)nlr.ret_val)->type), MP_OBJ_FROM_PTR(&mp_type_StopIteration))) {
-                    return MP_OBJ_STOP_ITERATION;
+                    return mp_make_stop_iteration(mp_obj_exception_get_value(MP_OBJ_FROM_PTR(nlr.ret_val)));
                 } else {
                     nlr_jump(nlr.ret_val);
                 }
@@ -1272,7 +1280,6 @@ mp_obj_t mp_iternext(mp_obj_t o_in) {
     }
 }
 
-// TODO: Unclear what to do with StopIterarion exception here.
 mp_vm_return_kind_t mp_resume(mp_obj_t self_in, mp_obj_t send_value, mp_obj_t throw_value, mp_obj_t *ret_val) {
     assert((send_value != MP_OBJ_NULL) ^ (throw_value != MP_OBJ_NULL));
     const mp_obj_type_t *type = mp_obj_get_type(self_in);
@@ -1282,13 +1289,18 @@ mp_vm_return_kind_t mp_resume(mp_obj_t self_in, mp_obj_t send_value, mp_obj_t th
     }
 
     if (type->iternext != NULL && send_value == mp_const_none) {
+        MP_STATE_THREAD(stop_iteration_arg) = MP_OBJ_NULL;
         mp_obj_t ret = type->iternext(self_in);
         *ret_val = ret;
         if (ret != MP_OBJ_STOP_ITERATION) {
             return MP_VM_RETURN_YIELD;
         } else {
-            // Emulate raise StopIteration()
-            // Special case, handled in vm.c
+            // The generator is finished.
+            // This is an optimised "raise StopIteration(*ret_val)".
+            *ret_val = MP_STATE_THREAD(stop_iteration_arg);
+            if (*ret_val == MP_OBJ_NULL) {
+                *ret_val = mp_const_none;
+            }
             return MP_VM_RETURN_NORMAL;
         }
     }
@@ -1559,13 +1571,24 @@ NORETURN void mp_raise_NotImplementedError(mp_rom_error_text_t msg) {
 
 #endif
 
+NORETURN void mp_raise_type_arg(const mp_obj_type_t *exc_type, mp_obj_t arg) {
+    nlr_raise(mp_obj_new_exception_arg1(exc_type, arg));
+}
+
+NORETURN void mp_raise_StopIteration(mp_obj_t arg) {
+    if (arg == MP_OBJ_NULL) {
+        mp_raise_type(&mp_type_StopIteration);
+    } else {
+        mp_raise_type_arg(&mp_type_StopIteration, arg);
+    }
+}
+
 NORETURN void mp_raise_OSError(int errno_) {
-    nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(errno_)));
+    mp_raise_type_arg(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(errno_));
 }
 
 #if MICROPY_STACK_CHECK || MICROPY_ENABLE_PYSTACK
 NORETURN void mp_raise_recursion_depth(void) {
-    nlr_raise(mp_obj_new_exception_arg1(&mp_type_RuntimeError,
-        MP_OBJ_NEW_QSTR(MP_QSTR_maximum_space_recursion_space_depth_space_exceeded)));
+    mp_raise_type_arg(&mp_type_RuntimeError, MP_OBJ_NEW_QSTR(MP_QSTR_maximum_space_recursion_space_depth_space_exceeded));
 }
 #endif
diff --git a/py/runtime.h b/py/runtime.h
index 7d2cb94e8..f0d41f38d 100644
--- a/py/runtime.h
+++ b/py/runtime.h
@@ -154,6 +154,11 @@ mp_obj_t mp_iternext_allow_raise(mp_obj_t o); // may return MP_OBJ_STOP_ITERATIO
 mp_obj_t mp_iternext(mp_obj_t o); // will always return MP_OBJ_STOP_ITERATION instead of raising StopIteration(...)
 mp_vm_return_kind_t mp_resume(mp_obj_t self_in, mp_obj_t send_value, mp_obj_t throw_value, mp_obj_t *ret_val);
 
+static inline mp_obj_t mp_make_stop_iteration(mp_obj_t o) {
+    MP_STATE_THREAD(stop_iteration_arg) = o;
+    return MP_OBJ_STOP_ITERATION;
+}
+
 mp_obj_t mp_make_raise_obj(mp_obj_t o);
 
 mp_obj_t mp_import_name(qstr name, mp_obj_t fromlist, mp_obj_t level);
@@ -179,6 +184,8 @@ NORETURN void mp_raise_TypeError(mp_rom_error_text_t msg);
 NORETURN void mp_raise_NotImplementedError(mp_rom_error_text_t msg);
 #endif
 
+NORETURN void mp_raise_type_arg(const mp_obj_type_t *exc_type, mp_obj_t arg);
+NORETURN void mp_raise_StopIteration(mp_obj_t arg);
 NORETURN void mp_raise_OSError(int errno_);
 NORETURN void mp_raise_recursion_depth(void);
 
diff --git a/py/vm.c b/py/vm.c
index 5365014fc..bbfc9914e 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -1257,16 +1257,9 @@ yield:
                         PUSH(ret_value);
                         goto yield;
                     } else if (ret_kind == MP_VM_RETURN_NORMAL) {
-                        // Pop exhausted gen
-                        sp--;
-                        if (ret_value == MP_OBJ_STOP_ITERATION) {
-                            // Optimize StopIteration
-                            // TODO: get StopIteration's value
-                            PUSH(mp_const_none);
-                        } else {
-                            PUSH(ret_value);
-                        }
-
+                        // The generator has finished, and returned a value via StopIteration
+                        // Replace exhausted generator with the returned value
+                        SET_TOP(ret_value);
                         // If we injected GeneratorExit downstream, then even
                         // if it was swallowed, we re-raise GeneratorExit
                         GENERATOR_EXIT_IF_NEEDED(t_exc);
diff --git a/shared/README.md b/shared/README.md
new file mode 100644
index 000000000..073187b24
--- /dev/null
+++ b/shared/README.md
@@ -0,0 +1,3 @@
+This directory contains libraries, utilities and helper code developed
+specifically for this project.  The code is intended to be portable and
+usable by any port.
diff --git a/lib/embed/__errno.c b/shared/libc/__errno.c
similarity index 100%
rename from lib/embed/__errno.c
rename to shared/libc/__errno.c
diff --git a/lib/embed/abort_.c b/shared/libc/abort_.c
similarity index 100%
rename from lib/embed/abort_.c
rename to shared/libc/abort_.c
diff --git a/lib/utils/printf.c b/shared/libc/printf.c
similarity index 100%
rename from lib/utils/printf.c
rename to shared/libc/printf.c
diff --git a/lib/libc/string0.c b/shared/libc/string0.c
similarity index 100%
rename from lib/libc/string0.c
rename to shared/libc/string0.c
diff --git a/lib/memzip/README.md b/shared/memzip/README.md
similarity index 84%
rename from lib/memzip/README.md
rename to shared/memzip/README.md
index 287d0fc48..3938e3198 100644
--- a/lib/memzip/README.md
+++ b/shared/memzip/README.md
@@ -10,13 +10,13 @@ a C file which contains the data from the zip file.
 A typical addition to a makefile would look like:
 ```
 SRC_C += \
-    lib/memzip/import.c \
-    lib/memzip/lexermemzip.c \
-    lib/memzip/memzip.c \
+    shared/memzip/import.c \
+    shared/memzip/lexermemzip.c \
+    shared/memzip/memzip.c \
 
 OBJ += $(BUILD)/memzip-files.o
 
-MAKE_MEMZIP = ../lib/memzip/make-memzip.py
+MAKE_MEMZIP = ../shared/memzip/make-memzip.py
 
 $(BUILD)/memzip-files.o: $(BUILD)/memzip-files.c
     $(call compile_c)
diff --git a/lib/memzip/import.c b/shared/memzip/import.c
similarity index 100%
rename from lib/memzip/import.c
rename to shared/memzip/import.c
diff --git a/lib/memzip/lexermemzip.c b/shared/memzip/lexermemzip.c
similarity index 100%
rename from lib/memzip/lexermemzip.c
rename to shared/memzip/lexermemzip.c
diff --git a/lib/memzip/make-memzip.py b/shared/memzip/make-memzip.py
similarity index 100%
rename from lib/memzip/make-memzip.py
rename to shared/memzip/make-memzip.py
diff --git a/lib/memzip/memzip.c b/shared/memzip/memzip.c
similarity index 100%
rename from lib/memzip/memzip.c
rename to shared/memzip/memzip.c
diff --git a/lib/memzip/memzip.h b/shared/memzip/memzip.h
similarity index 100%
rename from lib/memzip/memzip.h
rename to shared/memzip/memzip.h
diff --git a/lib/netutils/dhcpserver.c b/shared/netutils/dhcpserver.c
similarity index 99%
rename from lib/netutils/dhcpserver.c
rename to shared/netutils/dhcpserver.c
index 7f97ee6e4..9db42b3fd 100644
--- a/lib/netutils/dhcpserver.c
+++ b/shared/netutils/dhcpserver.c
@@ -35,7 +35,7 @@
 
 #if MICROPY_PY_LWIP
 
-#include "lib/netutils/dhcpserver.h"
+#include "shared/netutils/dhcpserver.h"
 #include "lwip/udp.h"
 
 #define DHCPDISCOVER    (1)
diff --git a/lib/netutils/dhcpserver.h b/shared/netutils/dhcpserver.h
similarity index 100%
rename from lib/netutils/dhcpserver.h
rename to shared/netutils/dhcpserver.h
diff --git a/lib/netutils/netutils.c b/shared/netutils/netutils.c
similarity index 98%
rename from lib/netutils/netutils.c
rename to shared/netutils/netutils.c
index 40fbd5bca..84b4405c4 100644
--- a/lib/netutils/netutils.c
+++ b/shared/netutils/netutils.c
@@ -30,7 +30,7 @@
 #include <string.h>
 
 #include "py/runtime.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 
 // Takes an array with a raw IPv4 address and returns something like '192.168.0.1'.
 mp_obj_t netutils_format_ipv4_addr(uint8_t *ip, netutils_endian_t endian) {
diff --git a/lib/netutils/netutils.h b/shared/netutils/netutils.h
similarity index 100%
rename from lib/netutils/netutils.h
rename to shared/netutils/netutils.h
diff --git a/lib/netutils/trace.c b/shared/netutils/trace.c
similarity index 99%
rename from lib/netutils/trace.c
rename to shared/netutils/trace.c
index 1610966c2..a6dfb42c2 100644
--- a/lib/netutils/trace.c
+++ b/shared/netutils/trace.c
@@ -25,7 +25,7 @@
  */
 
 #include "py/mphal.h"
-#include "lib/netutils/netutils.h"
+#include "shared/netutils/netutils.h"
 
 static uint32_t get_be16(const uint8_t *buf) {
     return buf[0] << 8 | buf[1];
diff --git a/lib/mp-readline/readline.c b/shared/readline/readline.c
similarity index 99%
rename from lib/mp-readline/readline.c
rename to shared/readline/readline.c
index 296c8aa4a..cad85b4e6 100644
--- a/lib/mp-readline/readline.c
+++ b/shared/readline/readline.c
@@ -31,7 +31,7 @@
 #include "py/mpstate.h"
 #include "py/repl.h"
 #include "py/mphal.h"
-#include "lib/mp-readline/readline.h"
+#include "shared/readline/readline.h"
 
 #if 0 // print debugging info
 #define DEBUG_PRINT (1)
diff --git a/lib/mp-readline/readline.h b/shared/readline/readline.h
similarity index 100%
rename from lib/mp-readline/readline.h
rename to shared/readline/readline.h
diff --git a/lib/utils/gchelper.h b/shared/runtime/gchelper.h
similarity index 100%
rename from lib/utils/gchelper.h
rename to shared/runtime/gchelper.h
diff --git a/lib/utils/gchelper_generic.c b/shared/runtime/gchelper_generic.c
similarity index 99%
rename from lib/utils/gchelper_generic.c
rename to shared/runtime/gchelper_generic.c
index 3e7e33ab1..dcd35f9c7 100644
--- a/lib/utils/gchelper_generic.c
+++ b/shared/runtime/gchelper_generic.c
@@ -28,7 +28,7 @@
 
 #include "py/mpstate.h"
 #include "py/gc.h"
-#include "lib/utils/gchelper.h"
+#include "shared/runtime/gchelper.h"
 
 #if MICROPY_ENABLE_GC
 
diff --git a/lib/utils/gchelper_m0.s b/shared/runtime/gchelper_m0.s
similarity index 100%
rename from lib/utils/gchelper_m0.s
rename to shared/runtime/gchelper_m0.s
diff --git a/lib/utils/gchelper_m3.s b/shared/runtime/gchelper_m3.s
similarity index 100%
rename from lib/utils/gchelper_m3.s
rename to shared/runtime/gchelper_m3.s
diff --git a/lib/utils/gchelper_native.c b/shared/runtime/gchelper_native.c
similarity index 97%
rename from lib/utils/gchelper_native.c
rename to shared/runtime/gchelper_native.c
index 6bf386b51..1e4af9c84 100644
--- a/lib/utils/gchelper_native.c
+++ b/shared/runtime/gchelper_native.c
@@ -28,7 +28,7 @@
 
 #include "py/mpstate.h"
 #include "py/gc.h"
-#include "lib/utils/gchelper.h"
+#include "shared/runtime/gchelper.h"
 
 #if MICROPY_ENABLE_GC
 
diff --git a/lib/utils/interrupt_char.c b/shared/runtime/interrupt_char.c
similarity index 100%
rename from lib/utils/interrupt_char.c
rename to shared/runtime/interrupt_char.c
diff --git a/lib/utils/interrupt_char.h b/shared/runtime/interrupt_char.h
similarity index 100%
rename from lib/utils/interrupt_char.h
rename to shared/runtime/interrupt_char.h
diff --git a/lib/utils/mpirq.c b/shared/runtime/mpirq.c
similarity index 99%
rename from lib/utils/mpirq.c
rename to shared/runtime/mpirq.c
index 02139f24d..8e474bf5a 100644
--- a/lib/utils/mpirq.c
+++ b/shared/runtime/mpirq.c
@@ -29,7 +29,7 @@
 
 #include "py/runtime.h"
 #include "py/gc.h"
-#include "lib/utils/mpirq.h"
+#include "shared/runtime/mpirq.h"
 
 #if MICROPY_ENABLE_SCHEDULER
 
diff --git a/lib/utils/mpirq.h b/shared/runtime/mpirq.h
similarity index 100%
rename from lib/utils/mpirq.h
rename to shared/runtime/mpirq.h
diff --git a/lib/utils/pyexec.c b/shared/runtime/pyexec.c
similarity index 99%
rename from lib/utils/pyexec.c
rename to shared/runtime/pyexec.c
index 4446b36b6..006ec096f 100644
--- a/lib/utils/pyexec.c
+++ b/shared/runtime/pyexec.c
@@ -39,8 +39,8 @@
 #include "irq.h"
 #include "usb.h"
 #endif
-#include "lib/mp-readline/readline.h"
-#include "lib/utils/pyexec.h"
+#include "shared/readline/readline.h"
+#include "shared/runtime/pyexec.h"
 #include "genhdr/mpversion.h"
 
 pyexec_mode_kind_t pyexec_mode_kind = PYEXEC_MODE_FRIENDLY_REPL;
diff --git a/lib/utils/pyexec.h b/shared/runtime/pyexec.h
similarity index 100%
rename from lib/utils/pyexec.h
rename to shared/runtime/pyexec.h
diff --git a/lib/utils/semihosting.c b/shared/runtime/semihosting.c
similarity index 100%
rename from lib/utils/semihosting.c
rename to shared/runtime/semihosting.c
diff --git a/lib/utils/semihosting.h b/shared/runtime/semihosting.h
similarity index 100%
rename from lib/utils/semihosting.h
rename to shared/runtime/semihosting.h
diff --git a/shared/runtime/stdout_helpers.c b/shared/runtime/stdout_helpers.c
new file mode 100644
index 000000000..6a24cc2eb
--- /dev/null
+++ b/shared/runtime/stdout_helpers.c
@@ -0,0 +1,62 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <string.h>
+#include "py/mphal.h"
+
+/*
+ * Extra stdout functions
+ * These can be either optimized for a particular port, or reference
+ * implementation below can be used.
+ */
+
+// Send "cooked" string of given length, where every occurrence of
+// LF character is replaced with CR LF ("\n" is converted to "\r\n").
+// This is an optimised version to reduce the number of calls made
+// to mp_hal_stdout_tx_strn.
+void mp_hal_stdout_tx_strn_cooked(const char *str, size_t len) {
+    const char *last = str;
+    while (len--) {
+        if (*str == '\n') {
+            if (str > last) {
+                mp_hal_stdout_tx_strn(last, str - last);
+            }
+            mp_hal_stdout_tx_strn("\r\n", 2);
+            ++str;
+            last = str;
+        } else {
+            ++str;
+        }
+    }
+    if (str > last) {
+        mp_hal_stdout_tx_strn(last, str - last);
+    }
+}
+
+// Send zero-terminated string
+void mp_hal_stdout_tx_str(const char *str) {
+    mp_hal_stdout_tx_strn(str, strlen(str));
+}
diff --git a/lib/utils/sys_stdio_mphal.c b/shared/runtime/sys_stdio_mphal.c
similarity index 100%
rename from lib/utils/sys_stdio_mphal.c
rename to shared/runtime/sys_stdio_mphal.c
diff --git a/lib/timeutils/timeutils.c b/shared/timeutils/timeutils.c
similarity index 99%
rename from lib/timeutils/timeutils.c
rename to shared/timeutils/timeutils.c
index 7c74f5fc3..6bf3eca84 100644
--- a/lib/timeutils/timeutils.c
+++ b/shared/timeutils/timeutils.c
@@ -27,7 +27,7 @@
 
 #include "py/obj.h"
 
-#include "lib/timeutils/timeutils.h"
+#include "shared/timeutils/timeutils.h"
 
 // LEAPOCH corresponds to 2000-03-01, which is a mod-400 year, immediately
 // after Feb 29. We calculate seconds as a signed integer relative to that.
diff --git a/lib/timeutils/timeutils.h b/shared/timeutils/timeutils.h
similarity index 100%
rename from lib/timeutils/timeutils.h
rename to shared/timeutils/timeutils.h
diff --git a/lib/upytesthelper/upytesthelper.c b/shared/upytesthelper/upytesthelper.c
similarity index 100%
rename from lib/upytesthelper/upytesthelper.c
rename to shared/upytesthelper/upytesthelper.c
diff --git a/lib/upytesthelper/upytesthelper.h b/shared/upytesthelper/upytesthelper.h
similarity index 100%
rename from lib/upytesthelper/upytesthelper.h
rename to shared/upytesthelper/upytesthelper.h
diff --git a/tests/basics/gen_yield_from_stopped.py b/tests/basics/gen_yield_from_stopped.py
index 468679b61..82feefed0 100644
--- a/tests/basics/gen_yield_from_stopped.py
+++ b/tests/basics/gen_yield_from_stopped.py
@@ -16,3 +16,15 @@ try:
     next(run())
 except StopIteration:
     print("StopIteration")
+
+
+# Where "f" is a native generator
+def run():
+    print((yield from f))
+
+
+f = zip()
+try:
+    next(run())
+except StopIteration:
+    print("StopIteration")
diff --git a/tests/basics/stopiteration.py b/tests/basics/stopiteration.py
new file mode 100644
index 000000000..d4719c9bc
--- /dev/null
+++ b/tests/basics/stopiteration.py
@@ -0,0 +1,63 @@
+# test StopIteration interaction with generators
+
+try:
+    enumerate, exec
+except:
+    print("SKIP")
+    raise SystemExit
+
+
+def get_stop_iter_arg(msg, code):
+    try:
+        exec(code)
+        print("FAIL")
+    except StopIteration as er:
+        print(msg, er.args)
+
+
+class A:
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        raise StopIteration(42)
+
+
+class B:
+    def __getitem__(self, index):
+        # argument to StopIteration should get ignored
+        raise StopIteration(42)
+
+
+def gen(x):
+    return x
+    yield
+
+
+def gen2(x):
+    try:
+        yield
+    except ValueError:
+        pass
+    return x
+
+
+get_stop_iter_arg("next", "next(A())")
+get_stop_iter_arg("iter", "next(iter(B()))")
+get_stop_iter_arg("enumerate", "next(enumerate(A()))")
+get_stop_iter_arg("map", "next(map(lambda x:x, A()))")
+get_stop_iter_arg("zip", "next(zip(A()))")
+g = gen(None)
+get_stop_iter_arg("generator0", "next(g)")
+get_stop_iter_arg("generator1", "next(g)")
+g = gen(42)
+get_stop_iter_arg("generator0", "next(g)")
+get_stop_iter_arg("generator1", "next(g)")
+get_stop_iter_arg("send", "gen(None).send(None)")
+get_stop_iter_arg("send", "gen(42).send(None)")
+g = gen2(None)
+next(g)
+get_stop_iter_arg("throw", "g.throw(ValueError)")
+g = gen2(42)
+next(g)
+get_stop_iter_arg("throw", "g.throw(ValueError)")
diff --git a/tests/basics/string_fstring.py b/tests/basics/string_fstring.py
new file mode 100644
index 000000000..4f7225fca
--- /dev/null
+++ b/tests/basics/string_fstring.py
@@ -0,0 +1,51 @@
+def f():
+    return 4
+def g(_):
+    return 5
+def h():
+    return 6
+
+print(f'no interpolation')
+print(f"no interpolation")
+print(f"""no interpolation""")
+
+x, y = 1, 2
+print(f'{x}')
+print(f'{x:08x}')
+print(f'a {x} b {y} c')
+print(f'a {x:08x} b {y} c')
+
+print(f'a {"hello"} b')
+print(f'a {f() + g("foo") + h()} b')
+
+def foo(a, b):
+    return f'{x}{y}{a}{b}'
+print(foo(7, 8))
+
+# PEP-0498 specifies that '\\' and '#' must be disallowed explicitly, whereas
+# MicroPython relies on the syntax error as a result of the substitution.
+
+print(f"\\")
+print(f'#')
+try:
+    eval("f'{\}'")
+except SyntaxError:
+    print('SyntaxError')
+try:
+    eval("f'{#}'")
+except SyntaxError:
+    print('SyntaxError')
+
+
+# PEP-0498 specifies that handling of double braces '{{' or '}}' should
+# behave like str.format.
+print(f'{{}}')
+print(f'{{{4*10}}}', '{40}')
+
+# A single closing brace, unlike str.format should raise a syntax error.
+# MicroPython instead raises ValueError at runtime from the substitution.
+try:
+    eval("f'{{}'")
+except (ValueError, SyntaxError):
+    # MicroPython incorrectly raises ValueError here.
+    print('SyntaxError')
diff --git a/tests/basics/string_fstring_debug.py b/tests/basics/string_fstring_debug.py
new file mode 100644
index 000000000..76a448ca0
--- /dev/null
+++ b/tests/basics/string_fstring_debug.py
@@ -0,0 +1,23 @@
+# test f-string debug feature {x=}
+
+
+def f():
+    return 4
+
+
+def g(_):
+    return 5
+
+
+def h():
+    return 6
+
+
+x, y = 1, 2
+print(f"{x=}")
+print(f"{x=:08x}")
+print(f"a {x=} b {y} c")
+print(f"a {x=:08x} b {y} c")
+
+print(f'a {f() + g("foo") + h()=} b')
+print(f'a {f() + g("foo") + h()=:08x} b')
diff --git a/tests/basics/string_fstring_debug.py.exp b/tests/basics/string_fstring_debug.py.exp
new file mode 100644
index 000000000..563030f40
--- /dev/null
+++ b/tests/basics/string_fstring_debug.py.exp
@@ -0,0 +1,6 @@
+x=1
+x=00000001
+a x=1 b 2 c
+a x=00000001 b 2 c
+a f() + g("foo") + h()=15 b
+a f() + g("foo") + h()=0000000f b
diff --git a/tests/basics/subclass_native3.py b/tests/basics/subclass_native3.py
index ac5aabfed..0c45c4924 100644
--- a/tests/basics/subclass_native3.py
+++ b/tests/basics/subclass_native3.py
@@ -34,6 +34,26 @@ print(MyStopIteration().value)
 print(MyStopIteration(1).value)
 
 
+class Iter:
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        # This exception will stop the "yield from", with a value of 3
+        raise MyStopIteration(3)
+
+
+def gen():
+    print((yield from Iter()))
+    return 4
+
+
+try:
+    next(gen())
+except StopIteration as er:
+    print(er.args)
+
+
 class MyOSError(OSError):
     pass
 
diff --git a/tests/basics/unary_op.py b/tests/basics/unary_op.py
index bd78a20d0..2239e2b20 100644
--- a/tests/basics/unary_op.py
+++ b/tests/basics/unary_op.py
@@ -23,5 +23,12 @@ print(not A())
 # check user instances derived from builtins
 class B(int): pass
 print(not B())
+print(True if B() else False)
 class C(list): pass
 print(not C())
+print(True if C() else False)
+# type doesn't define unary_op
+class D(type): pass
+d = D("foo", (), {})
+print(not d)
+print(True if d else False)
diff --git a/tests/cmdline/cmd_parsetree.py b/tests/cmdline/cmd_parsetree.py
index 50da36954..483ea8937 100644
--- a/tests/cmdline/cmd_parsetree.py
+++ b/tests/cmdline/cmd_parsetree.py
@@ -10,3 +10,4 @@ d = b"bytes"
 e = b"a very long bytes that will not be interned"
 f = 123456789012345678901234567890
 g = 123
+h = f"fstring: '{b}'"
diff --git a/tests/cmdline/cmd_parsetree.py.exp b/tests/cmdline/cmd_parsetree.py.exp
index e64f4f782..cc8ba82c0 100644
--- a/tests/cmdline/cmd_parsetree.py.exp
+++ b/tests/cmdline/cmd_parsetree.py.exp
@@ -1,6 +1,6 @@
 ----------------
-[   4] \(rule\|file_input_2\)(1) (n=9)
-         tok(4)
+[   4] \(rule\|file_input_2\)(1) (n=10)
+         tok(6)
 [   4]   \(rule\|for_stmt\)(22) (n=4)
            id(i)
 [   4]     \(rule\|atom_paren\)(45) (n=1)
@@ -9,7 +9,7 @@
            NULL
 [   6]   \(rule\|expr_stmt\)(5) (n=2)
            id(a)
-           tok(14)
+           tok(16)
 [   7]   \(rule\|expr_stmt\)(5) (n=2)
            id(b)
            str(str)
@@ -28,6 +28,16 @@
 [  12]   \(rule\|expr_stmt\)(5) (n=2)
            id(g)
            int(123)
+[  13]   \(rule\|expr_stmt\)(5) (n=2)
+           id(h)
+[  13]     \(rule\|atom_expr_normal\)(44) (n=2)
+[  13]       literal const(\.\+)
+[  13]       \(rule\|atom_expr_trailers\)(142) (n=2)
+[  13]         \(rule\|trailer_period\)(50) (n=1)
+                 id(format)
+[  13]         \(rule\|trailer_paren\)(48) (n=1)
+[  13]           \(rule\|arglist\)(164) (n=1)
+                   id(b)
 ----------------
 File cmdline/cmd_parsetree.py, code block '<module>' (descriptor: \.\+, bytecode @\.\+ bytes)
 Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
@@ -46,6 +56,7 @@ arg names:
   bc=32 line=10
   bc=37 line=11
   bc=42 line=12
+  bc=48 line=13
 00 BUILD_TUPLE 0
 02 GET_ITER_STACK
 03 FOR_ITER 12
@@ -65,8 +76,13 @@ arg names:
 39 STORE_NAME f
 42 LOAD_CONST_SMALL_INT 123
 45 STORE_NAME g
-48 LOAD_CONST_NONE
-49 RETURN_VALUE
+48 LOAD_CONST_OBJ \.\+
+50 LOAD_METHOD format
+53 LOAD_NAME b (cache=0)
+57 CALL_METHOD n=1 nkw=0
+59 STORE_NAME h
+62 LOAD_CONST_NONE
+63 RETURN_VALUE
 mem: total=\\d\+, current=\\d\+, peak=\\d\+
 stack: \\d\+ out of \\d\+
 GC: total: \\d\+, used: \\d\+, free: \\d\+
diff --git a/tests/cpydiff/core_fstring_concat.py b/tests/cpydiff/core_fstring_concat.py
new file mode 100644
index 000000000..fd83527b5
--- /dev/null
+++ b/tests/cpydiff/core_fstring_concat.py
@@ -0,0 +1,12 @@
+"""
+categories: Core
+description: f-strings don't support concatenation with adjacent literals if the adjacent literals contain braces
+cause: MicroPython is optimised for code space.
+workaround: Use the + operator between literal strings when either is an f-string
+"""
+
+x = 1
+print("aa" f"{x}")
+print(f"{x}" "ab")
+print("a{}a" f"{x}")
+print(f"{x}" "a{}b")
diff --git a/tests/cpydiff/core_fstring_parser.py b/tests/cpydiff/core_fstring_parser.py
new file mode 100644
index 000000000..6917f3cfa
--- /dev/null
+++ b/tests/cpydiff/core_fstring_parser.py
@@ -0,0 +1,9 @@
+"""
+categories: Core
+description: f-strings cannot support expressions that require parsing to resolve nested braces
+cause: MicroPython is optimised for code space.
+workaround: Only use simple expressions inside f-strings
+"""
+
+f'{"hello {} world"}'
+f"{repr({})}"
diff --git a/tests/cpydiff/core_fstring_raw.py b/tests/cpydiff/core_fstring_raw.py
new file mode 100644
index 000000000..84e265f70
--- /dev/null
+++ b/tests/cpydiff/core_fstring_raw.py
@@ -0,0 +1,8 @@
+"""
+categories: Core
+description: Raw f-strings are not supported
+cause: MicroPython is optimised for code space.
+workaround: Unknown
+"""
+
+rf"hello"
diff --git a/tests/cpydiff/core_fstring_repr.py b/tests/cpydiff/core_fstring_repr.py
new file mode 100644
index 000000000..fcadcbf1b
--- /dev/null
+++ b/tests/cpydiff/core_fstring_repr.py
@@ -0,0 +1,18 @@
+"""
+categories: Core
+description: f-strings don't support the !r, !s, and !a conversions
+cause: MicroPython is optimised for code space.
+workaround: Use repr(), str(), and ascii() explictly.
+"""
+
+
+class X:
+    def __repr__(self):
+        return "repr"
+
+    def __str__(self):
+        return "str"
+
+
+print(f"{X()!r}")
+print(f"{X()!s}")
diff --git a/tests/cpydiff/modules_struct_whitespace_in_format.py b/tests/cpydiff/modules_struct_whitespace_in_format.py
new file mode 100644
index 000000000..a882b3856
--- /dev/null
+++ b/tests/cpydiff/modules_struct_whitespace_in_format.py
@@ -0,0 +1,13 @@
+"""
+categories: Modules,struct
+description: Struct pack with whitespace in format, whitespace ignored by CPython, error on uPy
+cause: MicroPython is optimised for code size.
+workaround: Don't use spaces in format strings.
+"""
+import struct
+
+try:
+    print(struct.pack("b b", 1, 2))
+    print("Should have worked")
+except:
+    print("struct.error")
diff --git a/tests/extmod/framebuf_palette.py b/tests/extmod/framebuf_palette.py
new file mode 100644
index 000000000..84db834c1
--- /dev/null
+++ b/tests/extmod/framebuf_palette.py
@@ -0,0 +1,35 @@
+# Test blit between different color spaces
+try:
+    import framebuf, usys
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+# Monochrome glyph/icon
+w = 8
+h = 8
+cbuf = bytearray(w * h // 8)
+fbc = framebuf.FrameBuffer(cbuf, w, h, framebuf.MONO_HLSB)
+fbc.line(0, 0, 7, 7, 1)
+
+# RGB565 destination
+wd = 16
+hd = 16
+dest = bytearray(wd * hd * 2)
+fbd = framebuf.FrameBuffer(dest, wd, hd, framebuf.RGB565)
+
+wp = 2
+bg = 0x1234
+fg = 0xF800
+pal = bytearray(wp * 2)
+palette = framebuf.FrameBuffer(pal, wp, 1, framebuf.RGB565)
+palette.pixel(0, 0, bg)
+palette.pixel(1, 0, fg)
+
+fbd.blit(fbc, 0, 0, -1, palette)
+
+print(fbd.pixel(0, 0) == fg)
+print(fbd.pixel(7, 7) == fg)
+print(fbd.pixel(8, 8) == 0)  # Ouside blit
+print(fbd.pixel(0, 1) == bg)
+print(fbd.pixel(1, 0) == bg)
diff --git a/tests/extmod/framebuf_palette.py.exp b/tests/extmod/framebuf_palette.py.exp
new file mode 100644
index 000000000..2e883c51d
--- /dev/null
+++ b/tests/extmod/framebuf_palette.py.exp
@@ -0,0 +1,5 @@
+True
+True
+True
+True
+True
diff --git a/tests/extmod/ujson_dump_separators.py b/tests/extmod/ujson_dump_separators.py
new file mode 100644
index 000000000..e19b99a26
--- /dev/null
+++ b/tests/extmod/ujson_dump_separators.py
@@ -0,0 +1,62 @@
+try:
+    from uio import StringIO
+    import ujson as json
+except:
+    try:
+        from io import StringIO
+        import json
+    except ImportError:
+        print("SKIP")
+        raise SystemExit
+
+for sep in [
+    None,
+    (", ", ": "),
+    (",", ": "),
+    (",", ":"),
+    [", ", ": "],
+    [",", ": "],
+    [",", ":"],
+]:
+    s = StringIO()
+    json.dump(False, s, separators=sep)
+    print(s.getvalue())
+
+    s = StringIO()
+    json.dump({"a": (2, [3, None])}, s, separators=sep)
+    print(s.getvalue())
+
+    # dump to a small-int not allowed
+    try:
+        json.dump(123, 1, separators=sep)
+    except (AttributeError, OSError):  # CPython and uPy have different errors
+        print("Exception")
+
+    # dump to an object not allowed
+    try:
+        json.dump(123, {}, separators=sep)
+    except (AttributeError, OSError):  # CPython and uPy have different errors
+        print("Exception")
+
+
+try:
+    s = StringIO()
+    json.dump(False, s, separators={"a": 1})
+except (TypeError, ValueError):  # CPython and uPy have different errors
+    print("Exception")
+
+# invalid separator types
+for sep in [1, object()]:
+    try:
+        s = StringIO()
+        json.dump(False, s, separators=sep)
+    except TypeError:
+        print("Exception")
+
+# too many/ not enough separators
+for sep in [(), (",", ":", "?"), (",",), []]:
+    try:
+        s = StringIO()
+        json.dump(False, s, separators=sep)
+    except ValueError:
+        print("Exception")
diff --git a/tests/extmod/ujson_dumps_separators.py b/tests/extmod/ujson_dumps_separators.py
new file mode 100644
index 000000000..efb541fe8
--- /dev/null
+++ b/tests/extmod/ujson_dumps_separators.py
@@ -0,0 +1,60 @@
+try:
+    import ujson as json
+except ImportError:
+    try:
+        import json
+    except ImportError:
+        print("SKIP")
+        raise SystemExit
+
+for sep in [
+    None,
+    (", ", ": "),
+    (",", ": "),
+    (",", ":"),
+    [", ", ": "],
+    [",", ": "],
+    [",", ":"],
+]:
+    print(json.dumps(False, separators=sep))
+    print(json.dumps(True, separators=sep))
+    print(json.dumps(None, separators=sep))
+    print(json.dumps(1, separators=sep))
+    print(json.dumps("abc", separators=sep))
+    print(json.dumps("\x00\x01\x7e", separators=sep))
+    print(json.dumps([], separators=sep))
+    print(json.dumps([1], separators=sep))
+    print(json.dumps([1, 2], separators=sep))
+    print(json.dumps([1, True], separators=sep))
+    print(json.dumps((), separators=sep))
+    print(json.dumps((1,), separators=sep))
+    print(json.dumps((1, 2), separators=sep))
+    print(json.dumps((1, (2, 3)), separators=sep))
+    print(json.dumps({}, separators=sep))
+    print(json.dumps({"a": 1}, separators=sep))
+    print(json.dumps({"a": (2, [3, None])}, separators=sep))
+    print(json.dumps('"quoted"', separators=sep))
+    print(json.dumps("space\n\r\tspace", separators=sep))
+    print(json.dumps({None: -1}, separators=sep))
+    print(json.dumps({False: 0}, separators=sep))
+    print(json.dumps({True: 1}, separators=sep))
+    print(json.dumps({1: 2}, separators=sep))
+
+try:
+    json.dumps(False, separators={"a": 1})
+except (TypeError, ValueError):  # CPython and uPy have different errors
+    print("Exception")
+
+# invalid separator types
+for sep in [1, object()]:
+    try:
+        json.dumps(False, separators=sep)
+    except TypeError:
+        print("Exception")
+
+# too many/ not enough separators
+for sep in [(), (",", ":", "?"), (",",), []]:
+    try:
+        json.dumps(False, separators=sep)
+    except ValueError:
+        print("Exception")
diff --git a/tests/extmod/vfs_fat_finaliser.py b/tests/extmod/vfs_fat_finaliser.py
index e30f42f84..b67afc2d9 100644
--- a/tests/extmod/vfs_fat_finaliser.py
+++ b/tests/extmod/vfs_fat_finaliser.py
@@ -56,6 +56,13 @@ micropython.heap_unlock()
 # Here we test that the finaliser is actually called during a garbage collection.
 import gc
 
+# Do a large number of single-block allocations to move the GC head forwards,
+# ensuring that the files are allocated from never-before-used blocks and
+# therefore couldn't possibly have any references to them left behind on
+# the stack.
+for i in range(1024):
+    []
+
 N = 4
 for i in range(N):
     n = "x%d" % i
diff --git a/tests/feature_check/fstring.py b/tests/feature_check/fstring.py
new file mode 100644
index 000000000..14792bce0
--- /dev/null
+++ b/tests/feature_check/fstring.py
@@ -0,0 +1,3 @@
+# check whether f-strings (PEP-498) are supported
+a = 1
+print(f"a={a}")
diff --git a/tests/feature_check/fstring.py.exp b/tests/feature_check/fstring.py.exp
new file mode 100644
index 000000000..73cdb8bcc
--- /dev/null
+++ b/tests/feature_check/fstring.py.exp
@@ -0,0 +1 @@
+a=1
diff --git a/tests/micropython/native_misc.py b/tests/micropython/native_misc.py
index 7c5415375..f5ef807fe 100644
--- a/tests/micropython/native_misc.py
+++ b/tests/micropython/native_misc.py
@@ -38,3 +38,13 @@ def f(a):
 
 f(False)
 f(True)
+
+
+# stack settling in branch
+@micropython.native
+def f(a):
+    print(1, 2, 3, 4 if a else 5)
+
+
+f(False)
+f(True)
diff --git a/tests/micropython/native_misc.py.exp b/tests/micropython/native_misc.py.exp
index b3e1389ef..8eec04228 100644
--- a/tests/micropython/native_misc.py.exp
+++ b/tests/micropython/native_misc.py.exp
@@ -4,3 +4,5 @@
 6
 True
 False
+1 2 3 5
+1 2 3 4
diff --git a/tests/multi_bluetooth/ble_subscribe.py b/tests/multi_bluetooth/ble_subscribe.py
new file mode 100644
index 000000000..7cbcc6319
--- /dev/null
+++ b/tests/multi_bluetooth/ble_subscribe.py
@@ -0,0 +1,246 @@
+# Test for sending notifications to subscribed clients.
+
+from micropython import const
+import time, machine, bluetooth
+
+TIMEOUT_MS = 5000
+
+_IRQ_CENTRAL_CONNECT = const(1)
+_IRQ_CENTRAL_DISCONNECT = const(2)
+_IRQ_GATTS_WRITE = const(3)
+_IRQ_PERIPHERAL_CONNECT = const(7)
+_IRQ_PERIPHERAL_DISCONNECT = const(8)
+_IRQ_GATTC_CHARACTERISTIC_RESULT = const(11)
+_IRQ_GATTC_CHARACTERISTIC_DONE = const(12)
+_IRQ_GATTC_DESCRIPTOR_RESULT = const(13)
+_IRQ_GATTC_DESCRIPTOR_DONE = const(14)
+_IRQ_GATTC_READ_RESULT = const(15)
+_IRQ_GATTC_READ_DONE = const(16)
+_IRQ_GATTC_WRITE_DONE = const(17)
+_IRQ_GATTC_NOTIFY = const(18)
+_IRQ_GATTC_INDICATE = const(19)
+
+_CCCD_UUID = bluetooth.UUID(const(0x2902))
+
+SERVICE_UUID = bluetooth.UUID("A5A5A5A5-FFFF-9999-1111-5A5A5A5A5A5A")
+CHAR_UUID = bluetooth.UUID("00000000-1111-2222-3333-444444444444")
+CHAR = (
+    CHAR_UUID,
+    bluetooth.FLAG_READ | bluetooth.FLAG_WRITE | bluetooth.FLAG_NOTIFY | bluetooth.FLAG_INDICATE,
+)
+SERVICE = (
+    SERVICE_UUID,
+    (CHAR,),
+)
+SERVICES = (SERVICE,)
+
+waiting_events = {}
+
+
+def irq(event, data):
+    if event == _IRQ_CENTRAL_CONNECT:
+        print("_IRQ_CENTRAL_CONNECT")
+        waiting_events[event] = data[0]
+    elif event == _IRQ_CENTRAL_DISCONNECT:
+        print("_IRQ_CENTRAL_DISCONNECT")
+    elif event == _IRQ_GATTS_WRITE:
+        print("_IRQ_GATTS_WRITE", ble.gatts_read(data[-1]))
+    elif event == _IRQ_PERIPHERAL_CONNECT:
+        print("_IRQ_PERIPHERAL_CONNECT")
+        waiting_events[event] = data[0]
+    elif event == _IRQ_PERIPHERAL_DISCONNECT:
+        print("_IRQ_PERIPHERAL_DISCONNECT")
+    elif event == _IRQ_GATTC_CHARACTERISTIC_RESULT:
+        # conn_handle, def_handle, value_handle, properties, uuid = data
+        if data[-1] == CHAR_UUID:
+            print("_IRQ_GATTC_CHARACTERISTIC_RESULT", data[-1])
+            waiting_events[event] = data[2]
+        else:
+            return
+    elif event == _IRQ_GATTC_CHARACTERISTIC_DONE:
+        print("_IRQ_GATTC_CHARACTERISTIC_DONE")
+    elif event == _IRQ_GATTC_DESCRIPTOR_RESULT:
+        # conn_handle, dsc_handle, uuid = data
+        if data[-1] == _CCCD_UUID:
+            print("_IRQ_GATTC_DESCRIPTOR_RESULT", data[-1])
+            waiting_events[event] = data[1]
+        else:
+            return
+    elif event == _IRQ_GATTC_DESCRIPTOR_DONE:
+        print("_IRQ_GATTC_DESCRIPTOR_DONE")
+    elif event == _IRQ_GATTC_READ_RESULT:
+        print("_IRQ_GATTC_READ_RESULT", bytes(data[-1]))
+    elif event == _IRQ_GATTC_READ_DONE:
+        print("_IRQ_GATTC_READ_DONE", data[-1])
+    elif event == _IRQ_GATTC_WRITE_DONE:
+        print("_IRQ_GATTC_WRITE_DONE", data[-1])
+    elif event == _IRQ_GATTC_NOTIFY:
+        print("_IRQ_GATTC_NOTIFY", bytes(data[-1]))
+    elif event == _IRQ_GATTC_INDICATE:
+        print("_IRQ_GATTC_NOTIFY", bytes(data[-1]))
+
+    if event not in waiting_events:
+        waiting_events[event] = None
+
+
+def wait_for_event(event, timeout_ms):
+    t0 = time.ticks_ms()
+    while time.ticks_diff(time.ticks_ms(), t0) < timeout_ms:
+        if event in waiting_events:
+            return waiting_events.pop(event)
+        machine.idle()
+    raise ValueError("Timeout waiting for {}".format(event))
+
+
+# Acting in peripheral role.
+def instance0():
+    multitest.globals(BDADDR=ble.config("mac"))
+    ((char_handle,),) = ble.gatts_register_services(SERVICES)
+    print("gap_advertise")
+    ble.gap_advertise(20_000, b"\x02\x01\x06\x04\xffMPY")  # \x04\x09MPY
+    multitest.next()
+    try:
+        # Write initial characteristic value (will be read by client).
+        ble.gatts_write(char_handle, "periph0")  ###
+
+        # Wait for central to connect to us.
+        conn_handle = wait_for_event(_IRQ_CENTRAL_CONNECT, TIMEOUT_MS * 10)
+
+        # A
+        # Wait for a write to the characteristic from the central (to synchronise).
+        wait_for_event(_IRQ_GATTS_WRITE, TIMEOUT_MS)
+        print("sync A")
+        # This should be local-only.
+        ble.gatts_write(char_handle, "periph1")
+        time.sleep_ms(100)
+        # Update local-only, then force notify.
+        ble.gatts_write(char_handle, "periph2")
+        ble.gatts_notify(conn_handle, char_handle)  ###
+        time.sleep_ms(100)
+        # Update local and notify subscribers. No notification should be sent.
+        ble.gatts_write(char_handle, "periph3", True)
+        time.sleep_ms(100)
+        multitest.broadcast("A")
+
+        # B
+        # Synchronise with the client (which should now be subscribed for notify).
+        wait_for_event(_IRQ_GATTS_WRITE, TIMEOUT_MS)
+        print("sync B")
+        # This should be local-only (send_update=False).
+        ble.gatts_write(char_handle, "periph4", False)
+        time.sleep_ms(100)
+        # This should notify the subscribed client.
+        ble.gatts_write(char_handle, "periph5", True)  ###
+        time.sleep_ms(100)
+        multitest.broadcast("B")
+
+        # C
+        # Synchronise with the client (which should now be subscribed for indicate).
+        wait_for_event(_IRQ_GATTS_WRITE, TIMEOUT_MS)
+        print("sync C")
+        # This should be local-only (send_update=False).
+        ble.gatts_write(char_handle, "periph6", False)
+        time.sleep_ms(100)
+        # This should indicate the subscribed client.
+        ble.gatts_write(char_handle, "periph7", True)  ###
+        time.sleep_ms(100)
+        multitest.broadcast("C")
+
+        # D
+        # Synchronise with the client (which should now be unsubscribed).
+        wait_for_event(_IRQ_GATTS_WRITE, TIMEOUT_MS)
+        print("sync D")
+        # This should be local-only (send_update=False).
+        ble.gatts_write(char_handle, "periph8", False)
+        time.sleep_ms(100)
+        # This should be local-only (no more subscribers).
+        ble.gatts_write(char_handle, "periph9", True)
+        time.sleep_ms(100)
+        # Update local-only, then another force notify.
+        ble.gatts_write(char_handle, "periph10")
+        ble.gatts_notify(conn_handle, char_handle)  ###
+        time.sleep_ms(100)
+        multitest.broadcast("D")
+
+        # Wait for the central to disconnect.
+        wait_for_event(_IRQ_CENTRAL_DISCONNECT, TIMEOUT_MS)
+    finally:
+        ble.active(0)
+
+
+# Acting in central role.
+def instance1():
+    multitest.next()
+    try:
+        # Connect to peripheral and then disconnect.
+        print("gap_connect")
+        ble.gap_connect(*BDADDR)
+        conn_handle = wait_for_event(_IRQ_PERIPHERAL_CONNECT, TIMEOUT_MS)
+
+        # Discover characteristics.
+        ble.gattc_discover_characteristics(conn_handle, 1, 65535)
+        value_handle = wait_for_event(_IRQ_GATTC_CHARACTERISTIC_RESULT, TIMEOUT_MS)
+        wait_for_event(_IRQ_GATTC_CHARACTERISTIC_DONE, TIMEOUT_MS)
+
+        # Discover CCCD.
+        ble.gattc_discover_descriptors(conn_handle, value_handle, value_handle + 5)
+        cccd_handle = wait_for_event(_IRQ_GATTC_DESCRIPTOR_RESULT, TIMEOUT_MS)
+        wait_for_event(_IRQ_GATTC_DESCRIPTOR_DONE, TIMEOUT_MS)
+
+        # Issue read of characteristic, should get initial value.
+        print("gattc_read")
+        ble.gattc_read(conn_handle, value_handle)
+        wait_for_event(_IRQ_GATTC_READ_RESULT, TIMEOUT_MS)
+
+        # While the four states are active, all incoming notifications
+        # and indications will be printed by the event handler. We
+        # should only expect to see certain ones.
+
+        # Start unsubscribed.
+        # Write to the characteristic (triggers A).
+        print("gattc_write")
+        ble.gattc_write(conn_handle, value_handle, "central0", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Wait for A to complete.
+        multitest.wait("A")
+
+        # Subscribe for notify.
+        ble.gattc_write(conn_handle, cccd_handle, b"\x01\x00", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Write to the characteristic (triggers B).
+        print("gattc_write")
+        ble.gattc_write(conn_handle, value_handle, "central1", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Wait for B to complete.
+        multitest.wait("B")
+
+        # Subscribe for indicate.
+        ble.gattc_write(conn_handle, cccd_handle, b"\x02\x00", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Write to the characteristic (triggers C).
+        print("gattc_write")
+        ble.gattc_write(conn_handle, value_handle, "central2", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Wait for C to complete.
+        multitest.wait("C")
+
+        # Unsubscribe.
+        ble.gattc_write(conn_handle, cccd_handle, b"\x00\x00", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Write to the characteristic (triggers D).
+        print("gattc_write")
+        ble.gattc_write(conn_handle, value_handle, "central3", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Wait for D to complete.
+        multitest.wait("D")
+
+        # Disconnect from peripheral.
+        print("gap_disconnect:", ble.gap_disconnect(conn_handle))
+        wait_for_event(_IRQ_PERIPHERAL_DISCONNECT, TIMEOUT_MS)
+    finally:
+        ble.active(0)
+
+
+ble = bluetooth.BLE()
+ble.active(1)
+ble.irq(irq)
diff --git a/tests/multi_bluetooth/ble_subscribe.py.exp b/tests/multi_bluetooth/ble_subscribe.py.exp
new file mode 100644
index 000000000..e0b4ed2f4
--- /dev/null
+++ b/tests/multi_bluetooth/ble_subscribe.py.exp
@@ -0,0 +1,39 @@
+--- instance0 ---
+gap_advertise
+_IRQ_CENTRAL_CONNECT
+_IRQ_GATTS_WRITE b'central0'
+sync A
+_IRQ_GATTS_WRITE b'central1'
+sync B
+_IRQ_GATTS_WRITE b'central2'
+sync C
+_IRQ_GATTS_WRITE b'central3'
+sync D
+_IRQ_CENTRAL_DISCONNECT
+--- instance1 ---
+gap_connect
+_IRQ_PERIPHERAL_CONNECT
+_IRQ_GATTC_CHARACTERISTIC_RESULT UUID('00000000-1111-2222-3333-444444444444')
+_IRQ_GATTC_CHARACTERISTIC_DONE
+_IRQ_GATTC_DESCRIPTOR_RESULT UUID(0x2902)
+_IRQ_GATTC_DESCRIPTOR_DONE
+gattc_read
+_IRQ_GATTC_READ_RESULT b'periph0'
+_IRQ_GATTC_READ_DONE 0
+gattc_write
+_IRQ_GATTC_WRITE_DONE 0
+_IRQ_GATTC_NOTIFY b'periph2'
+_IRQ_GATTC_WRITE_DONE 0
+gattc_write
+_IRQ_GATTC_WRITE_DONE 0
+_IRQ_GATTC_NOTIFY b'periph5'
+_IRQ_GATTC_WRITE_DONE 0
+gattc_write
+_IRQ_GATTC_WRITE_DONE 0
+_IRQ_GATTC_NOTIFY b'periph7'
+_IRQ_GATTC_WRITE_DONE 0
+gattc_write
+_IRQ_GATTC_WRITE_DONE 0
+_IRQ_GATTC_NOTIFY b'periph10'
+gap_disconnect: True
+_IRQ_PERIPHERAL_DISCONNECT
diff --git a/tests/multi_net/udp_data.py b/tests/multi_net/udp_data.py
new file mode 100644
index 000000000..fd3e00918
--- /dev/null
+++ b/tests/multi_net/udp_data.py
@@ -0,0 +1,35 @@
+# Simple test of a UDP server and client transferring data
+
+import socket
+
+NUM_NEW_SOCKETS = 4
+NUM_TRANSFERS = 4
+PORT = 8000
+
+# Server
+def instance0():
+    multitest.globals(IP=multitest.get_network_ip())
+    multitest.next()
+    for i in range(NUM_NEW_SOCKETS):
+        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        s.bind(socket.getaddrinfo("0.0.0.0", PORT)[0][-1])
+        multitest.broadcast("server ready")
+        for j in range(NUM_TRANSFERS):
+            data, addr = s.recvfrom(1000)
+            print(data)
+            s.sendto(b"server to client %d %d" % (i, j), addr)
+        s.close()
+
+
+# Client
+def instance1():
+    multitest.next()
+    ai = socket.getaddrinfo(IP, PORT)[0][-1]
+    for i in range(NUM_NEW_SOCKETS):
+        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        multitest.wait("server ready")
+        for j in range(NUM_TRANSFERS):
+            s.sendto(b"client to server %d %d" % (i, j), ai)
+            data, addr = s.recvfrom(1000)
+            print(data)
+        s.close()
diff --git a/tests/pyb/i2c.py b/tests/pyb/i2c.py
index bc9dba878..c96884327 100644
--- a/tests/pyb/i2c.py
+++ b/tests/pyb/i2c.py
@@ -11,6 +11,6 @@ for bus in (-1, 0, 1):
 
 i2c = I2C(1)
 
-i2c.init(I2C.MASTER, baudrate=400000)
+i2c.init(I2C.CONTROLLER, baudrate=400000)
 print(i2c.scan())
 i2c.deinit()
diff --git a/tests/pyb/i2c_accel.py b/tests/pyb/i2c_accel.py
index 8c74fa60e..8b87d406d 100644
--- a/tests/pyb/i2c_accel.py
+++ b/tests/pyb/i2c_accel.py
@@ -11,7 +11,7 @@ accel_addr = 76
 
 pyb.Accel()  # this will init the MMA for us
 
-i2c = I2C(1, I2C.MASTER, baudrate=400000)
+i2c = I2C(1, I2C.CONTROLLER, baudrate=400000)
 
 print(i2c.scan())
 print(i2c.is_ready(accel_addr))
diff --git a/tests/pyb/i2c_error.py b/tests/pyb/i2c_error.py
index b17a26325..1228962f5 100644
--- a/tests/pyb/i2c_error.py
+++ b/tests/pyb/i2c_error.py
@@ -11,7 +11,7 @@ if not hasattr(pyb, "Accel"):
 pyb.Accel()
 
 # get I2C bus
-i2c = I2C(1, I2C.MASTER, dma=True)
+i2c = I2C(1, I2C.CONTROLLER, dma=True)
 
 # test polling mem_read
 pyb.disable_irq()
diff --git a/tests/pyb/pyb_f405.py b/tests/pyb/pyb_f405.py
index 243381056..d7431a11a 100644
--- a/tests/pyb/pyb_f405.py
+++ b/tests/pyb/pyb_f405.py
@@ -10,7 +10,7 @@ print(pyb.freq())
 print(type(pyb.rng()))
 
 # test HAL error specific to F405
-i2c = pyb.I2C(2, pyb.I2C.MASTER)
+i2c = pyb.I2C(2, pyb.I2C.CONTROLLER)
 try:
     i2c.recv(1, 1)
 except OSError as e:
diff --git a/tests/pyb/spi.py b/tests/pyb/spi.py
index 73d39e724..7df6aeb45 100644
--- a/tests/pyb/spi.py
+++ b/tests/pyb/spi.py
@@ -11,12 +11,14 @@ for bus in (-1, 0, 1, 2):
 spi = SPI(1)
 print(spi)
 
-spi = SPI(1, SPI.MASTER)
-spi = SPI(1, SPI.MASTER, baudrate=500000)
-spi = SPI(1, SPI.MASTER, 500000, polarity=1, phase=0, bits=8, firstbit=SPI.MSB, ti=False, crc=None)
-print(str(spi)[:28], str(spi)[49:])  # don't print baudrate/prescaler
+spi = SPI(1, SPI.CONTROLLER)
+spi = SPI(1, SPI.CONTROLLER, baudrate=500000)
+spi = SPI(
+    1, SPI.CONTROLLER, 500000, polarity=1, phase=0, bits=8, firstbit=SPI.MSB, ti=False, crc=None
+)
+print(str(spi)[:32], str(spi)[53:])  # don't print baudrate/prescaler
 
-spi.init(SPI.SLAVE, phase=1)
+spi.init(SPI.PERIPHERAL, phase=1)
 print(spi)
 try:
     # need to flush input before we get an error (error is what we want to test)
@@ -25,7 +27,7 @@ try:
 except OSError:
     print("OSError")
 
-spi.init(SPI.MASTER)
+spi.init(SPI.CONTROLLER)
 spi.send(1, timeout=100)
 print(spi.recv(1, timeout=100))
 print(spi.send_recv(1, timeout=100))
diff --git a/tests/pyb/spi.py.exp b/tests/pyb/spi.py.exp
index 473c173a5..661bace90 100644
--- a/tests/pyb/spi.py.exp
+++ b/tests/pyb/spi.py.exp
@@ -3,8 +3,8 @@ ValueError 0
 SPI 1
 SPI 2
 SPI(1)
-SPI(1, SPI.MASTER, baudrate= , polarity=1, phase=0, bits=8)
-SPI(1, SPI.SLAVE, polarity=1, phase=1, bits=8)
+SPI(1, SPI.CONTROLLER, baudrate= , polarity=1, phase=0, bits=8)
+SPI(1, SPI.PERIPHERAL, polarity=1, phase=1, bits=8)
 OSError
 b'\xff'
 b'\xff'
diff --git a/tests/pybnative/while.py b/tests/pybnative/while.py
index 0f397dd37..10625e871 100644
--- a/tests/pybnative/while.py
+++ b/tests/pybnative/while.py
@@ -1,4 +1,4 @@
-import pyb
+import time, pyb
 
 
 @micropython.native
@@ -8,7 +8,7 @@ def f(led, n, d):
     while i < n:
         print(i)
         led.toggle()
-        pyb.delay(d)
+        time.sleep_ms(d)
         i += 1
     led.off()
 
diff --git a/tests/run-multitests.py b/tests/run-multitests.py
index b4afc1e52..34389e429 100755
--- a/tests/run-multitests.py
+++ b/tests/run-multitests.py
@@ -46,6 +46,16 @@ class multitest:
         print("NEXT")
         multitest.flush()
     @staticmethod
+    def broadcast(msg):
+        print("BROADCAST", msg)
+        multitest.flush()
+    @staticmethod
+    def wait(msg):
+        msg = "BROADCAST " + msg
+        while True:
+            if sys.stdin.readline().rstrip() == msg:
+                return
+    @staticmethod
     def globals(**gs):
         for g in gs:
             print("SET {{}} = {{!r}}".format(g, gs[g]))
@@ -126,14 +136,12 @@ class PyInstanceSubProcess(PyInstance):
 
     def start_script(self, script):
         self.popen = subprocess.Popen(
-            self.argv,
+            self.argv + ["-c", script],
             stdin=subprocess.PIPE,
             stdout=subprocess.PIPE,
             stderr=subprocess.STDOUT,
             env=self.env,
         )
-        self.popen.stdin.write(script)
-        self.popen.stdin.close()
         self.finished = False
 
     def stop(self):
@@ -141,7 +149,7 @@ class PyInstanceSubProcess(PyInstance):
             self.popen.terminate()
 
     def readline(self):
-        sel = select.select([self.popen.stdout.raw], [], [], 0.1)
+        sel = select.select([self.popen.stdout.raw], [], [], 0.001)
         if not sel[0]:
             self.finished = self.popen.poll() is not None
             return None, None
@@ -152,6 +160,10 @@ class PyInstanceSubProcess(PyInstance):
         else:
             return str(out.rstrip(), "ascii"), None
 
+    def write(self, data):
+        self.popen.stdin.write(data)
+        self.popen.stdin.flush()
+
     def is_finished(self):
         return self.finished
 
@@ -220,6 +232,9 @@ class PyInstancePyboard(PyInstance):
             err = None
         return str(out.rstrip(), "ascii"), err
 
+    def write(self, data):
+        self.pyb.serial.write(data)
+
     def is_finished(self):
         return self.finished
 
@@ -318,7 +333,12 @@ def run_test_on_instances(test_file, num_instances, instances):
                 last_read_time[idx] = time.time()
                 if out is not None and not any(m in out for m in IGNORE_OUTPUT_MATCHES):
                     trace_instance_output(idx, out)
-                    output[idx].append(out)
+                    if out.startswith("BROADCAST "):
+                        for instance2 in instances:
+                            if instance2 is not instance:
+                                instance2.write(bytes(out, "ascii") + b"\r\n")
+                    else:
+                        output[idx].append(out)
                 if err is not None:
                     trace_instance_output(idx, err)
                     output[idx].append(err)
diff --git a/tests/run-tests.py b/tests/run-tests.py
index 619df5ed3..3e97a7c87 100755
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -290,6 +290,7 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
     skip_const = False
     skip_revops = False
     skip_io_module = False
+    skip_fstring = False
     skip_endian = False
     has_complex = True
     has_coverage = False
@@ -348,6 +349,11 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
         if output != b"uio\n":
             skip_io_module = True
 
+        # Check if fstring feature is enabled, and skip such tests if it doesn't
+        output = run_feature_check(pyb, args, base_path, "fstring.py")
+        if output != b"a=1\n":
+            skip_fstring = True
+
         # Check if emacs repl is supported, and skip such tests if it's not
         t = run_feature_check(pyb, args, base_path, "repl_emacs_check.py")
         if "True" not in str(t, "ascii"):
@@ -543,6 +549,7 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
         is_async = test_name.startswith(("async_", "uasyncio_"))
         is_const = test_name.startswith("const")
         is_io_module = test_name.startswith("io_")
+        is_fstring = test_name.startswith("string_fstring")
 
         skip_it = test_file in skip_tests
         skip_it |= skip_native and is_native
@@ -555,6 +562,7 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
         skip_it |= skip_const and is_const
         skip_it |= skip_revops and "reverse_op" in test_name
         skip_it |= skip_io_module and is_io_module
+        skip_it |= skip_fstring and is_fstring
 
         if args.list_tests:
             if not skip_it:
diff --git a/tools/autobuild/autobuild.sh b/tools/autobuild/autobuild.sh
index 049844381..a14c7890f 100755
--- a/tools/autobuild/autobuild.sh
+++ b/tools/autobuild/autobuild.sh
@@ -4,7 +4,8 @@
 #
 # Requirements:
 # - All toolchains must be in path (arm-none-eabi-gcc, xtensa-lx106-elf)
-# - IDF_PATH_V4 must be set
+# - IDF_PATH_V42 must be set
+# - IDF_PATH_V43 must be set
 # - MICROPY_AUTOBUILD_MICROPYTHON_REPO must be set to location of micropython repository
 # - MICROPY_AUTOBUILD_MAKE must be set to the make command to use, eg "make -j2"
 #
@@ -12,8 +13,13 @@
 # - MICROPY_AUTOBUILD_REMOTE_MACHINE can be set to a remote ssh machine to copy files to
 # - MICROPY_AUTOBUILD_REMOTE_DIR can be set to destination directory on remote machine
 
-if [ ! -d "$IDF_PATH_V4" ]; then
-    echo "must set IDF_PATH_V4"
+if [ ! -d "$IDF_PATH_V42" ]; then
+    echo "must set IDF_PATH_V42"
+    exit 1
+fi
+
+if [ ! -d "$IDF_PATH_V43" ]; then
+    echo "must set IDF_PATH_V43"
     exit 1
 fi
 
@@ -63,7 +69,8 @@ ${AUTODIR}/build-cc3200-latest.sh ${FW_TAG} ${LOCAL_FIRMWARE}
 cd ../esp8266
 ${AUTODIR}/build-esp8266-latest.sh ${FW_TAG} ${LOCAL_FIRMWARE}
 cd ../esp32
-${AUTODIR}/build-esp32-latest.sh ${IDF_PATH_V4} ${FW_TAG} ${LOCAL_FIRMWARE}
+${AUTODIR}/build-esp32-latest.sh ${IDF_PATH_V42} ${FW_TAG} ${LOCAL_FIRMWARE}
+${AUTODIR}/build-esp32-latest.sh ${IDF_PATH_V43} ${FW_TAG} ${LOCAL_FIRMWARE}
 cd ../rp2
 ${AUTODIR}/build-rp2-latest.sh ${FW_TAG} ${LOCAL_FIRMWARE}
 cd ../mimxrt
diff --git a/tools/autobuild/build-cc3200-latest.sh b/tools/autobuild/build-cc3200-latest.sh
index 3c6d40036..0cbdb9c42 100755
--- a/tools/autobuild/build-cc3200-latest.sh
+++ b/tools/autobuild/build-cc3200-latest.sh
@@ -8,7 +8,7 @@ function do_build() {
     shift
     echo "building $descr $board"
     build_dir=/tmp/cc3200-build-$board
-    $MICROPY_AUTOBUILD_MAKE -B $@ BTARGET=application BOARD=$board BUILD=$build_dir || exit 1
+    $MICROPY_AUTOBUILD_MAKE $@ BTARGET=application BOARD=$board BUILD=$build_dir || exit 1
     zip $dest_dir/$descr$fw_tag.zip $build_dir/mcuimg.bin
     rm -rf $build_dir
 }
diff --git a/tools/autobuild/build-esp32-latest.sh b/tools/autobuild/build-esp32-latest.sh
index e433332c9..92a12b2d5 100755
--- a/tools/autobuild/build-esp32-latest.sh
+++ b/tools/autobuild/build-esp32-latest.sh
@@ -39,7 +39,14 @@ fi
 
 source $idf_path/export.sh
 
-# build the versions
-do_build esp32 GENERIC FROZEN_MANIFEST=$(pwd)/boards/manifest_release.py
-do_build esp32spiram GENERIC_SPIRAM FROZEN_MANIFEST=$(pwd)/boards/manifest_release.py
-do_build tinypico UM_TINYPICO
+# build the boards, based on the IDF version
+if idf.py --version | grep -q v4.2; then
+    do_build esp32 GENERIC FROZEN_MANIFEST=$(pwd)/boards/manifest_release.py
+    do_build esp32spiram GENERIC_SPIRAM FROZEN_MANIFEST=$(pwd)/boards/manifest_release.py
+    do_build tinypico UM_TINYPICO
+    do_build wesp32 SIL_WESP32
+else
+    do_build esp32c3 GENERIC_C3
+    do_build tinys2 UM_TINYS2
+    do_build featherS2 UM_FEATHERS2
+fi
diff --git a/tools/autobuild/build-mimxrt-latest.sh b/tools/autobuild/build-mimxrt-latest.sh
index e36b294ac..4db65c091 100755
--- a/tools/autobuild/build-mimxrt-latest.sh
+++ b/tools/autobuild/build-mimxrt-latest.sh
@@ -34,3 +34,4 @@ fi
 do_build TEENSY40 TEENSY40 hex
 do_build TEENSY41 TEENSY41 hex
 do_build MIMXRT1020_EVK MIMXRT1020_EVK bin
+do_build MIMXRT1050_EVKB MIMXRT1050_EVKB bin
diff --git a/tools/autobuild/build-stm32-latest.sh b/tools/autobuild/build-stm32-latest.sh
index 226c14a41..283c8a45b 100755
--- a/tools/autobuild/build-stm32-latest.sh
+++ b/tools/autobuild/build-stm32-latest.sh
@@ -8,7 +8,7 @@ function do_build() {
     shift
     echo "building $descr $board"
     build_dir=/tmp/stm-build-$board
-    $MICROPY_AUTOBUILD_MAKE -B $@ BOARD=$board BUILD=$build_dir || exit 1
+    $MICROPY_AUTOBUILD_MAKE $@ BOARD=$board BUILD=$build_dir || exit 1
     mv $build_dir/firmware.dfu $dest_dir/$descr$fw_tag.dfu
     rm -rf $build_dir
 }
diff --git a/tools/ci.sh b/tools/ci.sh
index 9f2452cac..ac2e0b77d 100755
--- a/tools/ci.sh
+++ b/tools/ci.sh
@@ -86,12 +86,19 @@ function ci_esp32_setup_helper {
     git clone https://github.com/espressif/esp-idf.git
     git -C esp-idf checkout $1
     git -C esp-idf submodule update --init \
-        components/bt/controller/lib \
         components/bt/host/nimble/nimble \
         components/esp_wifi \
         components/esptool_py/esptool \
         components/lwip/lwip \
         components/mbedtls/mbedtls
+    if [ -d esp-idf/components/bt/controller/esp32 ]; then
+        git -C esp-idf submodule update --init \
+            components/bt/controller/lib_esp32 \
+            components/bt/controller/lib_esp32c3_family
+    else
+        git -C esp-idf submodule update --init \
+            components/bt/controller/lib
+    fi
     ./esp-idf/install.sh
 }
 
@@ -100,7 +107,7 @@ function ci_esp32_idf402_setup {
 }
 
 function ci_esp32_idf43_setup {
-    ci_esp32_setup_helper v4.3-beta2
+    ci_esp32_setup_helper v4.3
 }
 
 function ci_esp32_build {
@@ -110,6 +117,9 @@ function ci_esp32_build {
     make ${MAKEOPTS} -C ports/esp32
     make ${MAKEOPTS} -C ports/esp32 clean
     make ${MAKEOPTS} -C ports/esp32 USER_C_MODULES=../../../examples/usercmodule/micropython.cmake FROZEN_MANIFEST=$(pwd)/ports/esp32/boards/manifest.py
+    # if [ -d $IDF_PATH/components/esp32c3 ]; then
+    #     make ${MAKEOPTS} -C ports/esp32 BOARD=GENERIC_C3
+    # fi
     # if [ -d $IDF_PATH/components/esp32s2 ]; then
     #     make ${MAKEOPTS} -C ports/esp32 BOARD=GENERIC_S2
     # fi
@@ -180,6 +190,7 @@ function ci_nrf_setup {
 
 function ci_nrf_build {
     ports/nrf/drivers/bluetooth/download_ble_stack.sh s140_nrf52_6_1_1
+    make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/nrf submodules
     make ${MAKEOPTS} -C ports/nrf BOARD=pca10040
     make ${MAKEOPTS} -C ports/nrf BOARD=microbit
@@ -258,6 +269,7 @@ function ci_stm32_pyb_build {
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/stm32 submodules
     git submodule update --init lib/btstack
+    git submodule update --init lib/mynewt-nimble
     make ${MAKEOPTS} -C ports/stm32 BOARD=PYBV11 MICROPY_PY_WIZNET5K=5200 MICROPY_PY_CC3K=1 USER_C_MODULES=../../examples/usercmodule
     make ${MAKEOPTS} -C ports/stm32 BOARD=PYBD_SF2
     make ${MAKEOPTS} -C ports/stm32 BOARD=PYBD_SF6 NANBOX=1 MICROPY_BLUETOOTH_NIMBLE=0 MICROPY_BLUETOOTH_BTSTACK=1
@@ -268,6 +280,7 @@ function ci_stm32_pyb_build {
 function ci_stm32_nucleo_build {
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/stm32 submodules
+    git submodule update --init lib/mynewt-nimble
     make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_F091RC
     make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_H743ZI CFLAGS_EXTRA='-DMICROPY_PY_THREAD=1'
     make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_L073RZ
@@ -394,6 +407,14 @@ function ci_unix_standard_run_perfbench {
     (cd tests && MICROPY_CPYTHON3=python3 MICROPY_MICROPYTHON=../ports/unix/micropython ./run-perfbench.py 1000 1000)
 }
 
+function ci_unix_dev_build {
+    ci_unix_build_helper VARIANT=dev
+}
+
+function ci_unix_dev_run_tests {
+    ci_unix_run_tests_helper VARIANT=dev
+}
+
 function ci_unix_coverage_setup {
     sudo pip3 install setuptools
     sudo pip3 install pyelftools
@@ -508,6 +529,8 @@ function ci_unix_macos_build {
     #make ${MAKEOPTS} -C ports/unix deplibs
     make ${MAKEOPTS} -C ports/unix
     # check for additional compiler errors/warnings
+    make ${MAKEOPTS} -C ports/unix VARIANT=dev submodules
+    make ${MAKEOPTS} -C ports/unix VARIANT=dev
     make ${MAKEOPTS} -C ports/unix VARIANT=coverage submodules
     make ${MAKEOPTS} -C ports/unix VARIANT=coverage
 }
diff --git a/tools/codeformat.py b/tools/codeformat.py
index 81a3cdcf8..a5d64739a 100755
--- a/tools/codeformat.py
+++ b/tools/codeformat.py
@@ -39,12 +39,13 @@ PATHS = [
     "extmod/btstack/*.[ch]",
     "extmod/nimble/*.[ch]",
     "lib/mbedtls_errors/tester.c",
-    "lib/netutils/*.[ch]",
-    "lib/timeutils/*.[ch]",
-    "lib/utils/*.[ch]",
+    "shared/netutils/*.[ch]",
+    "shared/timeutils/*.[ch]",
+    "shared/runtime/*.[ch]",
     "mpy-cross/*.[ch]",
     "ports/*/*.[ch]",
     "ports/windows/msvc/**/*.[ch]",
+    "ports/nrf/modules/nrf/*.[ch]",
     "py/*.[ch]",
     # Python
     "drivers/**/*.py",
diff --git a/tools/gen-cpydiff.py b/tools/gen-cpydiff.py
index c9f58ec50..1d458d3dc 100644
--- a/tools/gen-cpydiff.py
+++ b/tools/gen-cpydiff.py
@@ -50,7 +50,6 @@ INDEXTEMPLATE = "../docs/differences/index_template.txt"
 INDEX = "index.rst"
 
 HEADER = ".. This document was generated by tools/gen-cpydiff.py\n\n"
-UIMPORTLIST = {"struct", "collections", "json"}
 CLASSMAP = {"Core": "Core language", "Types": "Builtin types"}
 INDEXPRIORITY = ["syntax", "core_language", "builtin_types", "modules"]
 RSTCHARS = ["=", "-", "~", "`", ":"]
@@ -94,21 +93,12 @@ def readfiles():
     return files
 
 
-def uimports(code):
-    """converts CPython module names into MicroPython equivalents"""
-    for uimport in UIMPORTLIST:
-        uimport = bytes(uimport, "utf8")
-        code = code.replace(uimport, b"u" + uimport)
-    return code
-
-
 def run_tests(tests):
     """executes all tests"""
     results = []
     for test in tests:
         with open(TESTPATH + test.name, "rb") as f:
-            input_cpy = f.read()
-        input_upy = uimports(input_cpy)
+            input_py = f.read()
 
         process = subprocess.Popen(
             CPYTHON3,
@@ -117,7 +107,7 @@ def run_tests(tests):
             stdin=subprocess.PIPE,
             stderr=subprocess.PIPE,
         )
-        output_cpy = [com.decode("utf8") for com in process.communicate(input_cpy)]
+        output_cpy = [com.decode("utf8") for com in process.communicate(input_py)]
 
         process = subprocess.Popen(
             MICROPYTHON,
@@ -126,7 +116,7 @@ def run_tests(tests):
             stdin=subprocess.PIPE,
             stderr=subprocess.PIPE,
         )
-        output_upy = [com.decode("utf8") for com in process.communicate(input_upy)]
+        output_upy = [com.decode("utf8") for com in process.communicate(input_py)]
 
         if output_cpy[0] == output_upy[0] and output_cpy[1] == output_upy[1]:
             status = "Supported"
diff --git a/tools/insert-usb-ids.py b/tools/insert-usb-ids.py
index b1d848ad4..9b53f3f68 100644
--- a/tools/insert-usb-ids.py
+++ b/tools/insert-usb-ids.py
@@ -8,6 +8,7 @@ import sys
 import re
 import string
 
+config_prefix = "MICROPY_HW_USB_"
 needed_keys = ("USB_PID_CDC_MSC", "USB_PID_CDC_HID", "USB_PID_CDC", "USB_VID")
 
 
@@ -16,10 +17,10 @@ def parse_usb_ids(filename):
     for line in open(filename).readlines():
         line = line.rstrip("\r\n")
         match = re.match("^#define\s+(\w+)\s+\(0x([0-9A-Fa-f]+)\)$", line)
-        if match and match.group(1).startswith("USBD_"):
-            key = match.group(1).replace("USBD", "USB")
+        if match and match.group(1).startswith(config_prefix):
+            key = match.group(1).replace(config_prefix, "USB_")
             val = match.group(2)
-            print("key =", key, "val =", val)
+            # print("key =", key, "val =", val)
             if key in needed_keys:
                 rv[key] = val
     for k in needed_keys:
diff --git a/tools/mpremote/mpremote/main.py b/tools/mpremote/mpremote/main.py
index d225bf2e4..6e2df5179 100644
--- a/tools/mpremote/mpremote/main.py
+++ b/tools/mpremote/mpremote/main.py
@@ -27,6 +27,7 @@ _PROG = "mpremote"
 
 _BUILTIN_COMMAND_EXPANSIONS = {
     # Device connection shortcuts.
+    "devs": "connect list",
     "a0": "connect /dev/ttyACM0",
     "a1": "connect /dev/ttyACM1",
     "a2": "connect /dev/ttyACM2",
@@ -166,7 +167,12 @@ def do_connect(args):
             for p in sorted(serial.tools.list_ports.comports()):
                 print(
                     "{} {} {:04x}:{:04x} {} {}".format(
-                        p.device, p.serial_number, p.vid, p.pid, p.manufacturer, p.product
+                        p.device,
+                        p.serial_number,
+                        p.vid if isinstance(p.vid, int) else 0,
+                        p.pid if isinstance(p.pid, int) else 0,
+                        p.manufacturer,
+                        p.product,
                     )
                 )
             return None
diff --git a/tools/mpremote/mpremote/pyboardextended.py b/tools/mpremote/mpremote/pyboardextended.py
index e3f259b39..ccd3098e3 100644
--- a/tools/mpremote/mpremote/pyboardextended.py
+++ b/tools/mpremote/mpremote/pyboardextended.py
@@ -1,4 +1,4 @@
-import os, re, serial, struct, time
+import io, os, re, serial, struct, time
 from errno import EPERM
 from .console import VT_ENABLED
 
@@ -24,26 +24,18 @@ fs_hook_cmds = {
 }
 
 fs_hook_code = """\
-import uos, uio, ustruct, micropython, usys
+import uos, uio, ustruct, micropython
 
+SEEK_SET = 0
 
 class RemoteCommand:
-    def __init__(self, use_second_port):
+    def __init__(self):
+        import uselect, usys
         self.buf4 = bytearray(4)
-        try:
-            import pyb
-            self.fout = pyb.USB_VCP()
-            if use_second_port:
-                self.fin = pyb.USB_VCP(1)
-            else:
-                self.fin = pyb.USB_VCP()
-        except:
-            import usys
-            self.fout = usys.stdout.buffer
-            self.fin = usys.stdin.buffer
-        import select
-        self.poller = select.poll()
-        self.poller.register(self.fin, select.POLLIN)
+        self.fout = usys.stdout.buffer
+        self.fin = usys.stdin.buffer
+        self.poller = uselect.poll()
+        self.poller.register(self.fin, uselect.POLLIN)
 
     def poll_in(self):
         for _ in self.poller.ipoll(1000):
@@ -213,13 +205,16 @@ class RemoteFile(uio.IOBase):
         c.end()
         return n
 
-    def seek(self, n):
+    def seek(self, n, whence=SEEK_SET):
         c = self.cmd
         c.begin(CMD_SEEK)
         c.wr_s8(self.fd)
         c.wr_s32(n)
+        c.wr_s8(whence)
         n = c.rd_s32()
         c.end()
+        if n < 0:
+            raise OSError(n)
         return n
 
 
@@ -313,8 +308,8 @@ class RemoteFS:
         return RemoteFile(c, fd, mode.find('b') == -1)
 
 
-def __mount(use_second_port):
-    uos.mount(RemoteFS(RemoteCommand(use_second_port)), '/remote')
+def __mount():
+    uos.mount(RemoteFS(RemoteCommand()), '/remote')
     uos.chdir('/remote')
 """
 
@@ -459,8 +454,12 @@ class PyboardCommand:
     def do_seek(self):
         fd = self.rd_s8()
         n = self.rd_s32()
+        whence = self.rd_s8()
         # self.log_cmd(f"seek {fd} {n}")
-        self.data_files[fd][0].seek(n)
+        try:
+            n = self.data_files[fd][0].seek(n, whence)
+        except io.UnsupportedOperation:
+            n = -1
         self.wr_s32(n)
 
     def do_write(self):
@@ -563,28 +562,14 @@ class PyboardExtended(Pyboard):
         self.device_name = dev
         self.mounted = False
 
-    def mount_local(self, path, dev_out=None):
+    def mount_local(self, path):
         fout = self.serial
-        if dev_out is not None:
-            try:
-                fout = serial.Serial(dev_out)
-            except serial.SerialException:
-                port = list(serial.tools.list_ports.grep(dev_out))
-                if not port:
-                    raise
-                for p in port:
-                    try:
-                        fout = serial.Serial(p.device)
-                        break
-                    except serial.SerialException:
-                        pass
         self.mounted = True
         if self.eval('"RemoteFS" in globals()') == b"False":
             self.exec_(fs_hook_code)
-        self.exec_("__mount(%s)" % (dev_out is not None))
+        self.exec_("__mount()")
         self.cmd = PyboardCommand(self.serial, fout, path)
         self.serial = SerialIntercept(self.serial, self.cmd)
-        self.dev_out = dev_out
 
     def soft_reset_with_mount(self, out_callback):
         self.serial.write(b"\x04")
@@ -610,7 +595,7 @@ class PyboardExtended(Pyboard):
             n = self.serial.inWaiting()
         self.serial.write(b"\x01")
         self.exec_(fs_hook_code)
-        self.exec_("__mount(%s)" % (self.dev_out is not None))
+        self.exec_("__mount()")
         self.exit_raw_repl()
         self.read_until(4, b">>> ")
         self.serial = SerialIntercept(self.serial, self.cmd)
diff --git a/tools/mpremote/setup.cfg b/tools/mpremote/setup.cfg
index 4e78d05a9..261369384 100644
--- a/tools/mpremote/setup.cfg
+++ b/tools/mpremote/setup.cfg
@@ -1,6 +1,6 @@
 [metadata]
 name = mpremote
-version = 0.0.5
+version = 0.0.6
 author = Damien George
 author_email = damien@micropython.org
 description = Tool for interacting remotely with MicroPython
diff --git a/tools/pyboard.py b/tools/pyboard.py
index e460c69e2..15ddfd745 100755
--- a/tools/pyboard.py
+++ b/tools/pyboard.py
@@ -659,23 +659,37 @@ def main():
     group.add_argument(
         "--soft-reset",
         default=True,
-        action=argparse.BooleanOptionalAction,
-        help="Whether to perform a soft reset when connecting to the board.",
+        action="store_true",
+        help="Whether to perform a soft reset when connecting to the board [default]",
     )
+    group.add_argument(
+        "--no-soft-reset",
+        action="store_false",
+        dest="soft_reset",
+    )
+    group = cmd_parser.add_mutually_exclusive_group()
     group.add_argument(
         "--follow",
         action="store_true",
+        default=None,
         help="follow the output after running the scripts [default if no scripts given]",
     )
     group.add_argument(
         "--no-follow",
+        action="store_false",
+        dest="follow",
+    )
+    group = cmd_parser.add_mutually_exclusive_group()
+    group.add_argument(
+        "--exclusive",
         action="store_true",
-        help="Do not follow the output after running the scripts.",
+        default=True,
+        help="Open the serial device for exclusive access [default]",
     )
     group.add_argument(
         "--no-exclusive",
-        action="store_true",
-        help="Do not try to open the serial device for exclusive access.",
+        action="store_false",
+        dest="exclusive",
     )
     cmd_parser.add_argument(
         "-f",
@@ -690,7 +704,7 @@ def main():
     # open the connection to the pyboard
     try:
         pyb = Pyboard(
-            args.device, args.baudrate, args.user, args.password, args.wait, not args.no_exclusive
+            args.device, args.baudrate, args.user, args.password, args.wait, args.exclusive
         )
     except PyboardError as er:
         print(er)
@@ -709,13 +723,13 @@ def main():
 
         def execbuffer(buf):
             try:
-                if args.no_follow:
-                    pyb.exec_raw_no_follow(buf)
-                    ret_err = None
-                else:
+                if args.follow is None or args.follow:
                     ret, ret_err = pyb.exec_raw(
                         buf, timeout=None, data_consumer=stdout_write_bytes
                     )
+                else:
+                    pyb.exec_raw_no_follow(buf)
+                    ret_err = None
             except PyboardError as er:
                 print(er)
                 pyb.close()
diff --git a/tools/tinytest-codegen.py b/tools/tinytest-codegen.py
index cba0b9448..f1169a34d 100755
--- a/tools/tinytest-codegen.py
+++ b/tools/tinytest-codegen.py
@@ -99,6 +99,9 @@ exclude_tests = (
     "misc/sys_settrace_loop.py",
     "misc/sys_settrace_generator.py",
     "misc/sys_settrace_features.py",
+    # don't have f-string
+    "basics/string_fstring.py",
+    "basics/string_fstring_debug.py",
 )
 
 output = []
diff --git a/tools/uncrustify.cfg b/tools/uncrustify.cfg
index 80542b903..88127112e 100644
--- a/tools/uncrustify.cfg
+++ b/tools/uncrustify.cfg
@@ -1409,11 +1409,11 @@ nl_start_of_file                = ignore   # ignore/add/remove/force
 nl_start_of_file_min            = 0        # unsigned number
 
 # Add or remove newline at the end of the file.
-nl_end_of_file                  = ignore   # ignore/add/remove/force
+nl_end_of_file                  = force    # ignore/add/remove/force
 
 # The minimum number of newlines at the end of the file (only used if
 # nl_end_of_file is 'add' or 'force').
-nl_end_of_file_min              = 0        # unsigned number
+nl_end_of_file_min              = 1        # unsigned number
 
 # Add or remove newline between '=' and '{'.
 nl_assign_brace                 = ignore   # ignore/add/remove/force