micropython/tests/extmod/machine_spi_rate.py

# Test machine.SPI data transfer rates
import sys


try:
    import time
    from machine import Pin, SPI
except ImportError:
    print("SKIP")
    raise SystemExit

MAX_DELTA_MS = 8

# Configure pins based on the port/board details.
# Values are tuples of (spi_id, sck, mosi, miso)
if "alif" in sys.platform:
    MAX_DELTA_MS = 20
    spi_instances = ((0, None, None, None),)
elif "pyboard" in sys.platform:
    spi_instances = (
        (1, None, None, None),  # "explicit choice of sck/mosi/miso is not implemented"
        (2, None, None, None),
    )
elif "rp2" in sys.platform:
    spi_instances = ((0, Pin(18), Pin(19), Pin(16)),)
elif "esp32" in sys.platform:
    impl = str(sys.implementation)
    if "ESP32C3" in impl or "ESP32C6" in impl:
        spi_instances = ((1, Pin(4), Pin(5), Pin(6)),)
    else:
        spi_instances = ((1, Pin(18), Pin(19), Pin(21)), (2, Pin(18), Pin(19), Pin(21)))
elif "esp8266" in sys.platform:
    MAX_DELTA_MS = 50  # port requires much looser timing requirements
    spi_instances = ((1, None, None, None),)  # explicit pin choice not allowed
else:
    print("Please add support for this test on this platform.")
    raise SystemExit


def get_real_baudrate(spi):
    # Return the 'real' baudrate for a SPI object, from parsing 'print' output
    # i.e.
    # SPI(id=1, baudrate=500000, polarity=0, phase=0, bits=8, firstbit=0, sck=14, mosi=13, miso=12)
    #
    # Note the 'real' rate may be quite different to the requested rate, i.e.
    # on ports where the SPI hardware only supports power of 2 clock dividers.
    #
    # Implementation is somewhat fiddly and inefficient to avoid dependency on
    # 're' module,
    s = str(spi)
    s = s.split("baudrate=")[1].split(",")[0]
    return int(s)


def test_instances():
    print_results = True
    for spi_id, sck, mosi, miso in spi_instances:
        for baudrate in (
            100_000,
            250_000,
            800_000,
            1_000_000,
            2_000_000,
            4_000_000,
            8_000_000,
        ):
            test_spi(
                spi_id,
                sck,
                mosi,
                miso,
                baudrate,
                0,
                0,
                print_results,
            )

        for baudrate in (100_000, 4_000_000):
            # Test the other polarity and phase settings
            for polarity, phase in ((0, 1), (1, 0), (1, 1)):
                test_spi(
                    spi_id,
                    sck,
                    mosi,
                    miso,
                    baudrate,
                    polarity,
                    phase,
                    print_results,
                )

        # Ensure the same test output regardless of how many SPI instances are tested
        print_results = False


wr_short = b"abcdefghijklmnop" * 10
rd_short = bytearray(len(wr_short))

wr_long = wr_short * 20
rd_long = bytearray(len(wr_long))


def test_spi(spi_id, sck, mosi, miso, baudrate, polarity, phase, print_results):
    if sck:
        s = SPI(
            spi_id,
            sck=sck,
            mosi=mosi,
            miso=miso,
            baudrate=baudrate,
            polarity=polarity,
            phase=phase,
        )
    else:
        s = SPI(spi_id, baudrate=baudrate, polarity=polarity, phase=phase)

    # to keep the test runtime down, use shorter buffer for lower baud rate
    wr_buf = wr_long if baudrate > 500_000 else wr_short
    rd_buf = rd_long if baudrate > 500_000 else rd_short

    real_baudrate = get_real_baudrate(s)
    assert real_baudrate
    transfer_time_ms = len(wr_buf) * 8 * 1000 // real_baudrate

    def test_write_readinto():
        s.write_readinto(wr_buf, rd_buf)

    def test_write():
        s.write(wr_buf)

    def test_readinto():
        s.readinto(rd_buf)

    for test_func, name in (
        (test_write_readinto, "write_readinto"),
        (test_write, "write"),
        (test_readinto, "readinto"),
    ):
        t0 = time.ticks_ms()
        test_func()
        transfer_time = time.ticks_diff(time.ticks_ms(), t0)
        t_delta = abs(transfer_time - transfer_time_ms)
        t_ok = t_delta < MAX_DELTA_MS

        if print_results or not t_ok:
            print(
                None if print_results else spi_id,
                baudrate,
                polarity,
                phase,
                name,
                t_ok or t_delta,
            )

    s.deinit()


test_instances()