Read PN532 UID from uart

pn532-uart-reader.py

# https://www.waveshare.com/wiki/PN532_NFC_HAT
# PN532 UART

import serial
import time


_port = '/dev/ttyUSB0'
_baudrate = 115200
_timeout = 2
_max_retry = 100


def open_port():
    return serial.Serial(
        port=_port,
        baudrate=_baudrate,
        parity=serial.PARITY_NONE,
        stopbits=serial.STOPBITS_ONE,
        bytesize=serial.EIGHTBITS,
        timeout=_timeout)




def wait_ser(ser, timeout=_timeout):
    t = 0
    while ser.inWaiting() <= 0:
        if t > timeout:
            return False
        time.sleep(0.01)
        t += 0.01
    return True


def wake_reader(ser):
    cmd = '55 55 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF 03 FD D4 14 01 17 00'
    cmd = cmd.replace(' ', '')
    # expected resp for wake command
    resp = '00 00 FF 00 FF 00 00 00 FF 02 FE D5 15 16 00'.replace(' ', '').lower()
    ser.write(bytes.fromhex(cmd))

    if not wait_ser(ser):
        print('wait for reader resp timeout')
        return False
    data = ser.read(int(len(resp)/2))
    print(data.hex())
    return data.hex() == resp


def read_uid(ser):
    cmd = '00 00 FF 04 FC D4 4A 01 00 E1 00'
    cmd = cmd.replace(' ', '')
    header = '00 00 FF 0C F4 D5 4B 01 01 00 04 08 04'.replace(' ', '')
    header_len = len(header)
    trim_header = '00 00 ff 00 ff 00'.replace(' ', '')
    ser.write(bytes.fromhex(cmd))

    if not wait_ser(ser):
        print('wait for reader resp timeout')
        return False, None

    resp = ''
    while ser.inWaiting() > 0:
        resp += ser.read().hex()

    while resp.startswith(trim_header):
        resp = resp[len(trim_header):]

    if resp == '':
        return False, None

    return resp[header_len:][:-4], resp



ser = open_port()

while not wake_reader(ser):
    print('Wake up reader failed')
    time.sleep(1)

while True:
    uid, resp = read_uid(ser)
    if uid:
        print(f'Found tag: {uid}')
    time.sleep(.1)