3f54e5dff2
Getting this test running on stm32- and mimxrt-based boards requires adding a small delay after constructing the UART so that the initial idle frame has time to be transmitted before the test starts. Also, the timing margin needs to account for an additional 1-bit worth of time on some MCUs. Thanks to @robert-hh for the esp32, mimxrt and samd settings. Signed-off-by: Damien George <damien@micropython.org>
61 lines
1.7 KiB
Python
61 lines
1.7 KiB
Python
# Test machine.UART transmission.
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# Does not require any external connections.
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try:
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from machine import UART
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except ImportError:
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print("SKIP")
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raise SystemExit
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import time, sys
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initial_delay_ms = 0
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bit_margin = 0
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timing_margin_us = 100
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# Configure pins based on the target.
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if "esp32" in sys.platform:
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uart_id = 1
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pins = {}
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timing_margin_us = 400
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elif "mimxrt" in sys.platform:
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uart_id = 1
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pins = {}
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initial_delay_ms = 20 # UART sends idle frame after init, so wait for that
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bit_margin = 1
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elif "pyboard" in sys.platform:
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uart_id = 4
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pins = {}
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initial_delay_ms = 50 # UART sends idle frame after init, so wait for that
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bit_margin = 1 # first start-bit must wait to sync with the UART clock
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elif "rp2" in sys.platform:
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uart_id = 0
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pins = {"tx": "GPIO0", "rx": "GPIO1"}
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timing_margin_us = 180
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elif "samd" in sys.platform:
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uart_id = 2
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pins = {"tx": "D1", "rx": "D0"}
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timing_margin_us = 300
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bit_margin = 1
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else:
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print("SKIP")
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raise SystemExit
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# Test that write+flush takes the expected amount of time to execute.
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for bits_per_s in (2400, 9600, 115200):
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text = "Hello World"
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uart = UART(uart_id, bits_per_s, bits=8, parity=None, stop=1, **pins)
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time.sleep_ms(initial_delay_ms)
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start_us = time.ticks_us()
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uart.write(text)
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uart.flush()
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duration_us = time.ticks_diff(time.ticks_us(), start_us)
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# 1(startbit) + 8(bits) + 1(stopbit) + 0(parity)
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bits_per_char = 10
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expect_us = (len(text)) * bits_per_char * 1_000_000 // bits_per_s
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delta_us = abs(duration_us - expect_us)
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margin_us = timing_margin_us + bit_margin * 1_000_000 // bits_per_s
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print(bits_per_s, delta_us <= margin_us or delta_us)
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