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#!/usr/bin/env python3# -*- coding: utf8 -*-##    MFRC522-Python#    A simple Python implementation for the MFRC522 NFC Card Reader for the Raspberry Pi.#    Original Author: Mario Gomez <mario.gomez@teubi.co>#    Modified by: Daniel Perron##    -------------------------------------------------------------------------------------#    Modified from danjperron's MFRC522-python repository.#    Repository Link: https://github.com/danjperron/MFRC522-python/blob/master/MFRC522.py#    Modified by: www.sunfounder.com#    Date: 2024/10/30#    Summary of Modifications:#    - Updated the `MFRC522_Read` function to return a tuple `(status, data)` instead of just printing the data.#    - Added comprehensive comments to all functions to enhance understandability and maintainability.##    License:#    This modified version is also licensed under the GNU Lesser General Public License v3.0.#    Please refer to the original license for more details.import spidev import signalimport timeDEBUG = Falseclass MFRC522:    MAX_LEN = 16    # Command Definitions    PCD_IDLE       = 0x00    PCD_AUTHENT    = 0x0E    PCD_RECEIVE    = 0x08    PCD_TRANSMIT   = 0x04    PCD_TRANSCEIVE = 0x0C    PCD_RESETPHASE = 0x0F    PCD_CALCCRC    = 0x03    # PICC Command Definitions    PICC_REQIDL     = 0x26    PICC_REQALL     = 0x52    PICC_ANTICOLL1  = 0x93    PICC_ANTICOLL2  = 0x95    PICC_ANTICOLL3  = 0x97    PICC_AUTHENT1A  = 0x60    PICC_AUTHENT1B  = 0x61    PICC_READ       = 0x30    PICC_WRITE      = 0xA0    PICC_DECREMENT  = 0xC0    PICC_INCREMENT  = 0xC1    PICC_RESTORE    = 0xC2    PICC_TRANSFER   = 0xB0    PICC_HALT       = 0x50    # Status Codes    MI_OK       = 0    MI_NOTAGERR = 1    MI_ERR      = 2    # Register Definitions    Reserved00     = 0x00    CommandReg     = 0x01    CommIEnReg     = 0x02    DivlEnReg      = 0x03    CommIrqReg     = 0x04    DivIrqReg      = 0x05    ErrorReg       = 0x06    Status1Reg     = 0x07    Status2Reg     = 0x08    FIFODataReg    = 0x09    FIFOLevelReg   = 0x0A    WaterLevelReg  = 0x0B    ControlReg     = 0x0C    BitFramingReg  = 0x0D    CollReg        = 0x0E    Reserved01     = 0x0F    Reserved10     = 0x10    ModeReg        = 0x11    TxModeReg      = 0x12    RxModeReg      = 0x13    TxControlReg   = 0x14    TxAutoReg      = 0x15    TxSelReg       = 0x16    RxSelReg       = 0x17    RxThresholdReg = 0x18    DemodReg       = 0x19    Reserved11     = 0x1A    Reserved12     = 0x1B    MifareReg      = 0x1C    Reserved13     = 0x1D    Reserved14     = 0x1E    SerialSpeedReg = 0x1F    Reserved20        = 0x20    CRCResultRegM     = 0x21    CRCResultRegL     = 0x22    Reserved21        = 0x23    ModWidthReg       = 0x24    Reserved22        = 0x25    RFCfgReg          = 0x26    GsNReg            = 0x27    CWGsPReg          = 0x28    ModGsPReg         = 0x29    TModeReg          = 0x2A    TPrescalerReg     = 0x2B    TReloadRegH       = 0x2C    TReloadRegL       = 0x2D    TCounterValueRegH = 0x2E    TCounterValueRegL = 0x2F    Reserved30      = 0x30    TestSel1Reg     = 0x31    TestSel2Reg     = 0x32    TestPinEnReg    = 0x33    TestPinValueReg = 0x34    TestBusReg      = 0x35    AutoTestReg     = 0x36    VersionReg      = 0x37    AnalogTestReg   = 0x38    TestDAC1Reg     = 0x39    TestDAC2Reg     = 0x3A    TestADCReg      = 0x3B    Reserved31      = 0x3C    Reserved32      = 0x3D    Reserved33      = 0x3E    Reserved34      = 0x3F    serNum = []    def __init__(self, bus=0, dev=0, spd=1000000):        """        Initialize the MFRC522 reader.                :param bus: SPI bus number (default=0)        :param dev: SPI device number (default=0)        :param spd: SPI speed in Hz (default=1000000)        """        self.spi = spidev.SpiDev()        self.spi.open(bus=bus, device=dev)        self.spi.max_speed_hz = spd        self.MFRC522_Init()    def MFRC522_Reset(self):        """        Reset the MFRC522 reader by sending the PCD_RESETPHASE command.        """        self.Write_MFRC522(self.CommandReg, self.PCD_RESETPHASE)    def Write_MFRC522(self, addr, val):        """        Write a value to a specific register.                :param addr: Register address        :param val: Value to write        """        self.spi.writebytes([((addr << 1) & 0x7E), val])    def Read_MFRC522(self, addr):        """        Read a value from a specific register.                :param addr: Register address        :return: Value read from the register        """        val = self.spi.xfer2([((addr << 1) & 0x7E) | 0x80, 0])        return val[1]    def SetBitMask(self, reg, mask):        """        Set specific bits (mask) in a register.                :param reg: Register address        :param mask: Bitmask to set        """        tmp = self.Read_MFRC522(reg)        self.Write_MFRC522(reg, tmp | mask)    def ClearBitMask(self, reg, mask):        """        Clear specific bits (mask) in a register.                :param reg: Register address        :param mask: Bitmask to clear        """        tmp = self.Read_MFRC522(reg)        self.Write_MFRC522(reg, tmp & (~mask))    def AntennaOn(self):        """        Turn the antenna on by setting the appropriate bits in the TxControlReg.        """        temp = self.Read_MFRC522(self.TxControlReg)        if not (temp & 0x03):            self.SetBitMask(self.TxControlReg, 0x03)    def AntennaOff(self):        """        Turn the antenna off by clearing the appropriate bits in the TxControlReg.        """        self.ClearBitMask(self.TxControlReg, 0x03)    def MFRC522_ToCard(self, command, sendData):        """        Communicate with the card by sending a command and data.                :param command: Command to send        :param sendData: Data to send        :return: Tuple containing (status, backData, backLen)        """        backData = []        backLen = 0        status = self.MI_ERR        irqEn = 0x00        waitIRq = 0x00        lastBits = None        n = 0        i = 0        if command == self.PCD_AUTHENT:            irqEn = 0x12            waitIRq = 0x10        if command == self.PCD_TRANSCEIVE:            irqEn = 0x77            waitIRq = 0x30        self.Write_MFRC522(self.CommIEnReg, irqEn | 0x80)        self.ClearBitMask(self.CommIrqReg, 0x80)        self.SetBitMask(self.FIFOLevelReg, 0x80)        self.Write_MFRC522(self.CommandReg, self.PCD_IDLE)        while i < len(sendData):            self.Write_MFRC522(self.FIFODataReg, sendData[i])            i += 1        self.Write_MFRC522(self.CommandReg, command)        if command == self.PCD_TRANSCEIVE:            self.SetBitMask(self.BitFramingReg, 0x80)        i = 2000        while True:            n = self.Read_MFRC522(self.CommIrqReg)            i -= 1            if ~((i != 0) and ~(n & 0x01) and ~(n & waitIRq)):                break        self.ClearBitMask(self.BitFramingReg, 0x80)        if i != 0:            if (self.Read_MFRC522(self.ErrorReg) & 0x1B) == 0x00:                status = self.MI_OK                if n & irqEn & 0x01:                    status = self.MI_NOTAGERR                if command == self.PCD_TRANSCEIVE:                    n = self.Read_MFRC522(self.FIFOLevelReg)                    lastBits = self.Read_MFRC522(self.ControlReg) & 0x07                    if lastBits != 0:                        backLen = (n - 1) * 8 + lastBits                    else:                        backLen = n * 8                    if n == 0:                        n = 1                    if n > self.MAX_LEN:                        n = self.MAX_LEN                    i = 0                    while i < n:                        backData.append(self.Read_MFRC522(self.FIFODataReg))                        i += 1            else:                status = self.MI_ERR        return (status, backData, backLen)    def MFRC522_Request(self, reqMode):        """        Request a tag to respond.                :param reqMode: Request mode (e.g., PICC_REQIDL)        :return: Tuple containing (status, backBits)        """        status = None        backBits = None        TagType = []        self.Write_MFRC522(self.BitFramingReg, 0x07)        TagType.append(reqMode)        (status, backData, backBits) = self.MFRC522_ToCard(self.PCD_TRANSCEIVE, TagType)        if ((status != self.MI_OK) | (backBits != 0x10)):            status = self.MI_ERR        return (status, backBits)    def MFRC522_Anticoll(self, anticollN):        """        Perform anti-collision detection to retrieve the UID.                :param anticollN: Anti-collision level (e.g., PICC_ANTICOLL1)        :return: Tuple containing (status, backData)        """        backData = []        serNumCheck = 0        serNum = []        self.Write_MFRC522(self.BitFramingReg, 0x00)        serNum.append(anticollN)        serNum.append(0x20)        (status, backData, backBits) = self.MFRC522_ToCard(self.PCD_TRANSCEIVE, serNum)        if status == self.MI_OK:            i = 0            if len(backData) == 5:                while i < 4:                    serNumCheck ^= backData[i]                    i += 1                if serNumCheck != backData[i]:                    status = self.MI_ERR            else:                status = self.MI_ERR        return (status, backData)    def MFRC522_Anticoll1(self):        """        Perform anti-collision detection at level 1.                :return: Tuple containing (status, backData)        """        return self.MFRC522_Anticoll(self.PICC_ANTICOLL1)    def MFRC522_Anticoll2(self):        """        Perform anti-collision detection at level 2.                :return: Tuple containing (status, backData)        """        return self.MFRC522_Anticoll(self.PICC_ANTICOLL2)    def MFRC522_Anticoll3(self):        """        Perform anti-collision detection at level 3.                :return: Tuple containing (status, backData)        """        return self.MFRC522_Anticoll(self.PICC_ANTICOLL3)    def CalculateCRC(self, pIndata):        """        Calculate CRC for the given input data.                :param pIndata: List of input data bytes        :return: List containing the CRC result (two bytes)        """        self.ClearBitMask(self.DivIrqReg, 0x04)        self.SetBitMask(self.FIFOLevelReg, 0x80)        i = 0        while i < len(pIndata):            self.Write_MFRC522(self.FIFODataReg, pIndata[i])            i += 1        self.Write_MFRC522(self.CommandReg, self.PCD_CALCCRC)        i = 0xFF        while True:            n = self.Read_MFRC522(self.DivIrqReg)            i -= 1            if not ((i != 0) and not (n & 0x04)):                break        pOutData = []        pOutData.append(self.Read_MFRC522(self.CRCResultRegL))        pOutData.append(self.Read_MFRC522(self.CRCResultRegM))        return pOutData    def MFRC522_PcdSelect(self, serNum, anticollN):        """        Select the tag with the given UID.                :param serNum: UID of the tag        :param anticollN: Anti-collision level        :return: 1 if successful, 0 otherwise        """        backData = []        buf = []        buf.append(anticollN)        buf.append(0x70)        i = 0        while i < 5:            buf.append(serNum[i])            i += 1        pOut = self.CalculateCRC(buf)        buf.append(pOut[0])        buf.append(pOut[1])        (status, backData, backLen) = self.MFRC522_ToCard(self.PCD_TRANSCEIVE, buf)        if (status == self.MI_OK) and (backLen == 0x18):            if DEBUG:                print("Size: " + str(backData[0]))                print("PcdSelect {} {}".format(anticollN, backData))            return 1        else:            return 0    def MFRC522_PcdSelect1(self, serNum):        """        Select the tag with the given UID at anti-collision level 1.                :param serNum: UID of the tag        :return: 1 if successful, 0 otherwise        """        return self.MFRC522_PcdSelect(serNum, self.PICC_ANTICOLL1)    def MFRC522_PcdSelect2(self, serNum):        """        Select the tag with the given UID at anti-collision level 2.                :param serNum: UID of the tag        :return: 1 if successful, 0 otherwise        """        return self.MFRC522_PcdSelect(serNum, self.PICC_ANTICOLL2)    def MFRC522_PcdSelect3(self, serNum):        """        Select the tag with the given UID at anti-collision level 3.                :param serNum: UID of the tag        :return: 1 if successful, 0 otherwise        """        return self.MFRC522_PcdSelect(serNum, self.PICC_ANTICOLL3)    def MFRC522_Auth(self, authMode, BlockAddr, Sectorkey, serNum):        """        Authenticate access to a specific block using a key.                :param authMode: Authentication mode (e.g., PICC_AUTHENT1A)        :param BlockAddr: Block address to authenticate        :param Sectorkey: Authentication key (6 bytes)        :param serNum: UID of the tag        :return: Status code (MI_OK on success, otherwise error)        """        buff = []        # First byte should be the authMode (A or B)        buff.append(authMode)        # Second byte is the trailerBlock (usually 7)        buff.append(BlockAddr)        # Append the authKey (6 bytes)        i = 0        while i < len(Sectorkey):            buff.append(Sectorkey[i])            i += 1        i = 0        # Append the first 4 bytes of the UID        while i < 4:            buff.append(serNum[i])            i += 1        # Start the authentication process        (status, backData, backLen) = self.MFRC522_ToCard(self.PCD_AUTHENT, buff)        # Check for errors        if DEBUG:            if not (status == self.MI_OK):                print("AUTH ERROR!!")            if not (self.Read_MFRC522(self.Status2Reg) & 0x08) != 0:                print("AUTH ERROR(status2reg & 0x08) != 0")        # Return the status        return status    def MFRC522_StopCrypto1(self):        """        Stop encryption on the card.        """        self.ClearBitMask(self.Status2Reg, 0x08)    def MFRC522_Read(self, blockAddr):        """        Read data from the specified block on the RFID card.                :param blockAddr: The block number to read from.        :return: A tuple containing the status and the data read.                 (status, data) where status is MI_OK (0) on success, else an error code,                 and data is a list of bytes read from the block or None on failure.        """        recvData = []        recvData.append(self.PICC_READ)        recvData.append(blockAddr)        # Calculate CRC for the read command        pOut = self.CalculateCRC(recvData)        recvData.append(pOut[0])        recvData.append(pOut[1])        # Send the read command to the card        (status, backData, backLen) = self.MFRC522_ToCard(self.PCD_TRANSCEIVE, recvData)                if not (status == self.MI_OK):            print("Error while reading!")            return (status, None)                if len(backData) == 16:            print("Sector " + str(blockAddr) + " " + str(backData))            return (status, backData)        else:            print("Error: Invalid data length")            return (self.MI_ERR, None)    def MFRC522_Write(self, blockAddr, writeData):        """        Write data to the specified block on the RFID card.                :param blockAddr: The block number to write to.        :param writeData: A list of 16 bytes to write.        :return: None        """        buff = []        buff.append(self.PICC_WRITE)        buff.append(blockAddr)        # Calculate CRC for the write command        crc = self.CalculateCRC(buff)        buff.append(crc[0])        buff.append(crc[1])        # Send the write command to the card        (status, backData, backLen) = self.MFRC522_ToCard(self.PCD_TRANSCEIVE, buff)        if not (status == self.MI_OK) or not (backLen == 4) or not ((backData[0] & 0x0F) == 0x0A):            status = self.MI_ERR                print("%s backdata &0x0F == 0x0A %s" % (backLen, backData[0] & 0x0F))        if status == self.MI_OK:            i = 0            buf = []            while i < 16:                buf.append(writeData[i])                i += 1            # Calculate CRC for the data to be written            crc = self.CalculateCRC(buf)            buf.append(crc[0])            buf.append(crc[1])            # Send the data to be written to the card            (status, backData, backLen) = self.MFRC522_ToCard(self.PCD_TRANSCEIVE, buf)            if not (status == self.MI_OK) or not (backLen == 4) or not ((backData[0] & 0x0F) == 0x0A):                print("Error while writing")            if status == self.MI_OK:                print("Data written")    def MFRC522_DumpClassic1K(self, key, uid):        """        Dump data from all blocks in a Classic 1K card.                :param key: Authentication key        :param uid: UID of the tag        :return: None        """        i = 0        while i < 64:            status = self.MFRC522_Auth(self.PICC_AUTHENT1A, i, key, uid)            # Check if authenticated            if status == self.MI_OK:                self.MFRC522_Read(i)            else:                print("Authentication error")            i += 1    def MFRC522_Init(self):        """        Initialize the MFRC522 reader with default settings.        """        self.MFRC522_Reset()        self.Write_MFRC522(self.TModeReg, 0x8D)        self.Write_MFRC522(self.TPrescalerReg, 0x3E)        self.Write_MFRC522(self.TReloadRegL, 30)        self.Write_MFRC522(self.TReloadRegH, 0)        self.Write_MFRC522(self.TxAutoReg, 0x40)        self.Write_MFRC522(self.ModeReg, 0x3D)        self.AntennaOn()    def MFRC522_SelectTagSN(self):        """        Select the tag and retrieve its UID.                :return: Tuple containing (status, valid_uid)        """        valid_uid = []        (status, uid) = self.MFRC522_Anticoll1()        if status != self.MI_OK:            return (self.MI_ERR, [])        if DEBUG:            print("anticol1() {}".format(uid))        if self.MFRC522_PcdSelect1(uid) == 0:            return (self.MI_ERR, [])        if DEBUG:            print("pcdSelect1() {}".format(uid))        # Check if first byte is 0x88        if uid[0] == 0x88:            # Handle another type of card            valid_uid.extend(uid[1:4])            (status, uid) = self.MFRC522_Anticoll2()            if status != self.MI_OK:                return (self.MI_ERR, [])            if DEBUG:                print("Anticol2() {}".format(uid))            rtn = self.MFRC522_PcdSelect2(uid)            if DEBUG:                print("pcdSelect2 return={} uid={}".format(rtn, uid))            if rtn == 0:                return (self.MI_ERR, [])            if DEBUG:                print("PcdSelect2() {}".format(uid))            # Now check again if uid[0] is 0x88            if uid[0] == 0x88:                valid_uid.extend(uid[1:4])                (status, uid) = self.MFRC522_Anticoll3()                if status != self.MI_OK:                    return (self.MI_ERR, [])                if DEBUG:                    print("Anticol3() {}".format(uid))                if self.MFRC522_PcdSelect3(uid) == 0:                    return (self.MI_ERR, [])                if DEBUG:                    print("PcdSelect3() {}".format(uid))        valid_uid.extend(uid[0:4])        return (self.MI_OK, valid_uid)

Code:

>>> %Run MFRC522.py>>>