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68 lines
1.9 KiB
Python
68 lines
1.9 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 "alif" in sys.platform:
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uart_id = 1
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pins = {}
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bit_margin = 1
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elif "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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if "STM32WB" in sys.implementation._machine:
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uart_id = "LP1"
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else:
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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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