UART test code - sender & receiver, with CRC and ACK

code.py

import board
import time
import random
import binascii


SENDER = True  # False for RECEIVER
RECV_WAIT = 5_000_000_000


def send():
    outbuf = bytearray(b'')
    data_length = random.randrange(0, 32)
    for _ in range(0, data_length):
        outbuf.extend(f"{random.randrange(0, 256):02X}".encode())
    crc = f"{binascii.crc32(outbuf):08x}".encode()
    outbuf.extend(crc)
    outbuf.extend(b'\n')
    written = uart.write(outbuf)
    print(f"🔵 WRITTEN: {written} {outbuf} {crc}")

def recv():
    rcvd = False
    if uart.in_waiting:
        waiting = uart.in_waiting
        inbuf = uart.readline()
        if inbuf:
            body = inbuf[0:len(inbuf)-9]
            crc_calc = f"{binascii.crc32(body):08x}".encode()
            crc_read = inbuf[len(inbuf)-9:len(inbuf)-1]
            if crc_calc == crc_read:
                rcvd = True
                print(f"🟢 READ: {waiting} {len(inbuf)} {crc_calc} {crc_read} {inbuf}")
            else:
                print(f"🟠 READ: {waiting} {len(inbuf)} {crc_calc} {crc_read} {inbuf}")
        else:
            print(f"🟡 {waiting} nothing read")  # shouldn't get here
    else:
        # print(f"⚪️ nothing waiting")
        pass
    return rcvd


uart = board.UART()

while True:
    if SENDER:
        send()
        if not recv():
            print(f"🔴 no ACK received")
        time.sleep(1)
    else:
        if recv():
            send()