nfc_reader.py

import time
import binascii

from pn532pi import Pn532, pn532
from pn532pi import Pn532I2c
from pn532pi import Pn532Spi
from pn532pi import Pn532Hsu


PN532_I2C = Pn532I2c(1)
nfc = Pn532(PN532_I2C)


def nfc_setup():
    nfc.begin()

    versiondata = nfc.getFirmwareVersion()
    if not versiondata:
        print("Didn't find PN53x board")
        raise RuntimeError("Didn't find PN53x board")  # halt

    # Got ok data, print it out!
    print("Found chip PN5 {:#x} Firmware ver. {:d}.{:d}".format((versiondata >> 24) & 0xFF, (versiondata >> 16) & 0xFF,
                                                                (versiondata >> 8) & 0xFF))
    # Set the max number of retry attempts to read from a card
    # This prevents us from waiting forever for a card, which is
    # the default behaviour of the pn532.
    nfc.setPassiveActivationRetries(0xFF)

    # configure board to read RFID tags
    nfc.SAMConfig()

    print("Waiting for an ISO14443A card")


def nfc_loop():
    # Wait for an ISO14443A type cards (Mifare, etc.).  When one is found
    # 'uid' will be populated with the UID, and uidLength will indicate
    # if the uid is 4 bytes (Mifare Classic) or 7 bytes (Mifare Ultralight)
    success, uid = nfc.readPassiveTargetID(pn532.PN532_MIFARE_ISO14443A_106KBPS)

    if (success):
        print("Found a card!")
        print("UID Length: {:d}".format(len(uid)))
        print("UID Value: {}".format(binascii.hexlify(uid)))
        # Wait 1 second before continuing
        time.sleep(1)
        return uid
    else:
        # pn532 probably timed out waiting for a card
        print("Timed out waiting for a card")
        return False