RFID čtečka NXP MFRC522

cmake_minimum_required(VERSION 3.12)

include($ENV{PICO_SDK_PATH}/external/pico_sdk_import.cmake)

project(rfid-rc522)

pico_sdk_init()


add_executable(rfid-rc522
        example.c
	mfrc522.c
        )

target_link_libraries(rfid-rc522 pico_stdlib hardware_spi)

# create map/bin/hex file etc.
pico_add_extra_outputs(rfid-rc522)
pico_enable_stdio_usb(rfid-rc522 1)
pico_enable_stdio_uart(rfid-rc522 0)

#include "mfrc522.h"

void main() {
    stdio_init_all();

    // Declare card UID's
    uint8_t tag2[] = {0x19, 0x09, 0x29, 0x3e};
    uint8_t tag1[] = {0x5a, 0x23, 0xc8, 0x4f};

    MFRC522Ptr_t mfrc = MFRC522_Init();
    PCD_Init(mfrc, spi0);

    sleep_ms(5000);

    // char test_result = PCD_SelfTest(mfrc);

    // if (test_result == 0) {
    //     printf("Self Test:  SUCCESS");
    // } else {
    //    printf("Self Test: FAILED");
    // }

    while(1) {
        //Wait for new card
        printf("Waiting for card\n\r");
        while(!PICC_IsNewCardPresent(mfrc));
        //Select the card
        printf("Selecting card\n\r");
        PICC_ReadCardSerial(mfrc);

        //Show UID on serial monitor
        printf("PICC dump: \n\r");
        PICC_DumpToSerial(mfrc, &(mfrc->uid));

        //Authorization with uid
        printf("Uid is: ");
        for(int i = 0; i < 4; i++) {
            printf("%x ", mfrc->uid.uidByte[i]);
        } printf("\n\r");

        if(memcmp(mfrc->uid.uidByte, tag1, 4) == 0 || memcmp(mfrc->uid.uidByte, tag2, 4) == 0 ) {
            printf("Authentication Success\n\r");
        } else {
            printf("Authentication Failed\n\r");
        }
    }
}

/**
* mfrc522 library for pi pico c/c++ sdk
* NOTE: Please also check the comments in MFRC522.h - they provide useful hints
* and background information.
*/

#include "mfrc522.h"

// ADT object allocation counter
static int MFRC_Instance_Counter = 0;

/**
 * Set up the data structures of an MFRC522 ADT object and return a pointer
 */
MFRC522Ptr_t MFRC522_Init() {
	// allocate instance struct array
	static struct MFRC522_T mfrc_Instances[MFRC_MAX_INSTANCES];
	//      static Chip_SSP_DATA_SETUP_T dataSetup_Instances[MFRC_MAX_INSTANCES];
	//		struct MFRC522_T mfrc_struct;
	//		Chip_SSP_DATA_SETUP_T data_setup;

	// initialize fields
	uint16_t i;
	for (i = 0; i < BUFFER_SIZE; i++) {
		mfrc_Instances[MFRC_Instance_Counter].Rx_Buf[i] = 0;
		mfrc_Instances[MFRC_Instance_Counter].Tx_Buf[i] = 0;
	}

	mfrc_Instances[MFRC_Instance_Counter]._chipSelectPin = cs_pin;

	// update instance counter
	MFRC_Instance_Counter++;

	return &(mfrc_Instances[MFRC_Instance_Counter - 1]);
} 



/*******************************************************************************
* Basic interface functions for communicating with the MFRC522
*******************************************************************************/

/**
 * Writes a uint8_t to the specified register in the MFRC522 chip.
 * The interface is described in the datasheet section 8.1.2.
 */
void PCD_WriteRegister(MFRC522Ptr_t mfrc, uint8_t reg, uint8_t value) {
	uint8_t msg[2];
	msg[0] = 0x00 | reg;
	msg[1] = value;

	cs_select(mfrc->_chipSelectPin);
	spi_write_blocking(mfrc->spi, msg, 2);
	cs_deselect(mfrc->_chipSelectPin);
}

/**
 * Writes a number of uint8_ts to the specified register in the MFRC522 chip.
 * The interface is described in the datasheet section 8.1.2.
 */
void PCD_WriteNRegister(
	MFRC522Ptr_t mfrc,
	uint8_t reg,   ///< The register to write to. One of the PCD_Register enums.
	uint8_t count, ///< The number of uint8_ts to write to the register
	uint8_t *values ///< The values to write. uint8_t array.
	) {
	uint8_t msg[count + 1]; //Values and address
	msg[0] = 0x00 | reg;

	uint8_t i;
	for(i = 0; i < count; i++) {
		msg[i + 1] = values[i];
	}

	cs_select(mfrc->_chipSelectPin);
	spi_write_blocking(mfrc->spi, msg, count + 1);
	cs_deselect(mfrc->_chipSelectPin);
}

/**
 * Reads a uint8_t from the specified register in the MFRC522 chip.
 * The interface is described in the datasheet section 8.1.2.
 */
uint8_t PCD_ReadRegister(
	MFRC522Ptr_t mfrc, 
	uint8_t reg ///< The register to read from. One of the PCD_Register enums
	) {
	uint8_t buf = 0;
	const uint8_t msg = 0x80 | reg;
	
	cs_select(mfrc->_chipSelectPin);
	spi_write_blocking(mfrc->spi, &msg, 1);
	spi_read_blocking(mfrc->spi, 0, &buf, 1);
	cs_deselect(mfrc->_chipSelectPin);
	return buf;
}

/**
 * Reads a number of uint8_ts from the specified register in the MFRC522 chip.
 * The interface is described in the datasheet section 8.1.2.
 */
void PCD_ReadNRegister(
	MFRC522Ptr_t mfrc,
	uint8_t reg, ///< The register to read from. One of the PCD_Register enums.
	uint8_t count,   ///< The number of uint8_ts to read
	uint8_t *values, ///< uint8_t array to store the values in.
	uint8_t rxAlign ///< Only bit positions rxAlign..7 in values[0] are updated.
	) {
	uint8_t buf = 0;
	const uint8_t msg = 0x80 | reg;
	
	cs_select(mfrc->_chipSelectPin);

	// uint8_t i;
	// for(i = 0; i < count; i++) {
	// 	uint8_t value = 0;
	// 	spi_write_blocking(mfrc->spi, &msg, 1);
	// 	spi_read_blocking(mfrc->spi, 0, &value, 1);
	// 	values[i] = value;
	// }

	uint8_t i;
	for(i = 0; i < count; i++) {
		values[i] = PCD_ReadRegister(mfrc, msg);
	}

	cs_deselect(mfrc->_chipSelectPin);
}

/**
 * Sets the bits given in mask in register reg.
 */
void PCD_SetRegisterBitMask(
	MFRC522Ptr_t mfrc,
	uint8_t reg, ///< The register to update. One of the PCD_Register enums.
	uint8_t mask ///< The bits to set.
	) {
	uint8_t tmp;
	tmp = PCD_ReadRegister(mfrc, reg);
	PCD_WriteRegister(mfrc, reg, tmp | mask); // set bit mask
} // End PCD_SetRegisterBitMask()

/**
 * Clears the bits given in mask from register reg.
 */
void PCD_ClearRegisterBitMask(
	MFRC522Ptr_t mfrc,
	uint8_t reg, ///< The register to update. One of the PCD_Register enums.
	uint8_t mask ///< The bits to clear.
	) {
	uint8_t tmp;
	tmp = PCD_ReadRegister(mfrc, reg);
	PCD_WriteRegister(mfrc, reg, tmp & (~mask)); // clear bit mask
} // End PCD_ClearRegisterBitMask()

/**
 * Use the CRC coprocessor in the MFRC522 to calculate a CRC_A.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode
PCD_CalculateCRC(MFRC522Ptr_t mfrc,
				 uint8_t *data,  ///< In: Pointer to the data to transfer to the
								 ///FIFO for CRC calculation.
				 uint8_t length, ///< In: The number of uint8_ts to transfer.
				 uint8_t *result ///< Out: Pointer to result buffer. Result is
								 ///written to result[0..1], low uint8_t first.
				 ) {
	PCD_WriteRegister(mfrc, CommandReg, PCD_Idle); // Stop any active command.
	PCD_WriteRegister(mfrc, DivIrqReg,
					  0x04); // Clear the CRCIRq interrupt request bit
	PCD_SetRegisterBitMask(mfrc, FIFOLevelReg,
						   0x80); // FlushBuffer = 1, FIFO initialization
	PCD_WriteNRegister(mfrc, FIFODataReg, length,
					   data);						  // Write data to the FIFO
	PCD_WriteRegister(mfrc, CommandReg, PCD_CalcCRC); // Start the calculation

	// Wait for the CRC calculation to complete. Each iteration of the
	// while-loop takes 17.73�s.
	uint16_t i = 5000;
	uint8_t n;
	while (1) {
		n = PCD_ReadRegister(mfrc, DivIrqReg); // DivIrqReg[7..0] bits are: Set2
											   // reserved reserved MfinActIRq
											   // reserved CRCIRq reserved
											   // reserved
		if (n & 0x04) { // CRCIRq bit set - calculation done
			break;
		}
		if (--i == 0) { // The emergency break. We will eventually terminate on
						// this one after 89ms. Communication with the MFRC522
						// might be down.
			return STATUS_TIMEOUT;
		}
	}
	PCD_WriteRegister(
		mfrc, CommandReg,
		PCD_Idle); // Stop calculating CRC for new content in the FIFO.

	// Transfer the result from the registers to the result buffer
	result[0] = PCD_ReadRegister(mfrc, CRCResultRegL);
	result[1] = PCD_ReadRegister(mfrc, CRCResultRegH);
	return STATUS_OK;
} // End PCD_CalculateCRC()

/*******************************************************************************
* Functions for manipulating the MFRC522
*******************************************************************************/

/**
 * Initializes the MFRC522 chip.
 */
void PCD_Init(MFRC522Ptr_t mfrc, spi_inst_t *spi) {

	mfrc->spi = spi0;
	gpio_put(RESET_PIN, 0);
    sleep_ms(1000);
    gpio_put(RESET_PIN, 1);
	sleep_ms(50);

    gpio_init(cs_pin);
    gpio_set_dir(cs_pin, GPIO_OUT);
    gpio_put(cs_pin, 1);

    spi_init(spi0, 1000000);

    spi_set_format(spi0, 8, 0, 0, SPI_MSB_FIRST);

    gpio_set_function(sck_pin, GPIO_FUNC_SPI);
    gpio_set_function(mosi_pin, GPIO_FUNC_SPI);
    gpio_set_function(miso_pin, GPIO_FUNC_SPI);

	PCD_WriteRegister(mfrc, CommandReg, PCD_SoftReset);

	// When communicating with a PICC we need a timeout if something goes wrong.
	// f_timer = 13.56 MHz / (2*TPreScaler+1) where TPreScaler =
	// [TPrescaler_Hi:TPrescaler_Lo].
	// TPrescaler_Hi are the four low bits in TModeReg. TPrescaler_Lo is
	// TPrescalerReg.
	PCD_WriteRegister(mfrc, TModeReg, 0x80); // TAuto=1; timer starts
											 // automatically at the end of the
											 // transmission in all
											 // communication modes at all
											 // speeds
	PCD_WriteRegister(mfrc, TPrescalerReg,
					  0xA9); // TPreScaler = TModeReg[3..0]:TPrescalerReg, ie
							 // 0x0A9 = 169 => f_timer=40kHz, ie a timer period
							 // of 25�s.
	PCD_WriteRegister(
		mfrc, TReloadRegH,
		0x03); // Reload timer with 0x3E8 = 1000, ie 25ms before timeout.
	PCD_WriteRegister(mfrc, TReloadRegL, 0xE8);

	PCD_WriteRegister(mfrc, TxASKReg, 0x40); // Default 0x00. Force a 100 % ASK
											 // modulation independent of the
											 // ModGsPReg register setting
	PCD_WriteRegister(mfrc, ModeReg, 0x3D);  // Default 0x3F. Set the preset
											// value for the CRC coprocessor for
											// the CalcCRC command to 0x6363
											// (ISO 14443-3 part 6.2.4)
	PCD_AntennaOn(mfrc); // Enable the antenna driver pins TX1 and TX2 (they
						 // were disabled by the reset)
} // End PCD_Init()

/**
 * Performs a soft reset on the MFRC522 chip and waits for it to be ready again.
 */
void PCD_Reset(MFRC522Ptr_t mfrc) {
	PCD_WriteRegister(mfrc, CommandReg,
					  PCD_SoftReset); // Issue the SoftReset command.
	// The datasheet does not mention how long the SoftRest command takes to
	// complete.
	// But the MFRC522 might have been in soft power-down mode (triggered by bit
	// 4 of CommandReg)
	// Section 8.8.2 in the datasheet says the oscillator start-up time is the
	// start up time of the crystal + 37,74�s. Let us be generous: 50ms.
	//SysTick_Init();
	sleep_ms(50);
	// Wait for the PowerDown bit in CommandReg to be cleared
	while (PCD_ReadRegister(mfrc, CommandReg) & (1 << 4)) {
		// PCD still restarting - unlikely after waiting 50ms, but better safe
		// than sorry.
	}
} // End PCD_Reset()

/**
 * Turns the antenna on by enabling pins TX1 and TX2.
 * After a reset these pins are disabled.
 */
void PCD_AntennaOn(MFRC522Ptr_t mfrc) {
	uint8_t value = PCD_ReadRegister(mfrc, TxControlReg);
	if ((value & 0x03) != 0x03) {
		PCD_WriteRegister(mfrc, TxControlReg, value | 0x03);
	}
} // End PCD_AntennaOn()

/**
 * Turns the antenna off by disabling pins TX1 and TX2.
 */
void PCD_AntennaOff(MFRC522Ptr_t mfrc) {
	PCD_ClearRegisterBitMask(mfrc, TxControlReg, 0x03);
} // End PCD_AntennaOff()

/**
 * Get the current MFRC522 Receiver Gain (RxGain[2:0]) value.
 * See 9.3.3.6 / table 98 in http://www.nxp.com/documents/data_sheet/MFRC522.pdf
 * NOTE: Return value scrubbed with (0x07<<4)=01110000b as RCFfgReg may use
 *reserved bits.
 *
 * @return Value of the RxGain, scrubbed to the 3 bits used.
 */
uint8_t PCD_GetAntennaGain(MFRC522Ptr_t mfrc) {
	return PCD_ReadRegister(mfrc, RFCfgReg) & (0x07 << 4);
} // End PCD_GetAntennaGain()

/**
 * Set the MFRC522 Receiver Gain (RxGain) to value specified by given mask.
 * See 9.3.3.6 / table 98 in http://www.nxp.com/documents/data_sheet/MFRC522.pdf
 * NOTE: Given mask is scrubbed with (0x07<<4)=01110000b as RCFfgReg may use
 * reserved bits.
 */
void PCD_SetAntennaGain(MFRC522Ptr_t mfrc, uint8_t mask) {
	if (PCD_GetAntennaGain(mfrc) != mask) { // only bother if there is a change
		PCD_ClearRegisterBitMask(
			mfrc, RFCfgReg, (0x07 << 4)); // clear needed to allow 000 pattern
		PCD_SetRegisterBitMask(mfrc, RFCfgReg,
							   mask & (0x07 << 4)); // only set RxGain[2:0] bits
	}
} // End PCD_SetAntennaGain()

/**
 * Performs the MFRC522 self test described in 16.1.1
 * Returns 0 if test is ok. Check what version of MFRC522 and put the buffer values in SELF_TEST_BYTES[]
*/
uint8_t PCD_SelfTest(MFRC522Ptr_t mfrc) {

    //Perform a soft reset
    PCD_WriteRegister(mfrc, CommandReg, PCD_SoftReset);
    sleep_ms(50); //Allow the chip to reset
    //printf("Soft reset complete\n\r");

    //Clear the internal buffer by writing 25 bytes of 00h (and implement the config command)??.
    PCD_WriteRegister(mfrc, FIFOLevelReg, 0x80); //FIFOLevel indicates nbr of bytes in FIFO buffer. MSB = 1 -> Flush

    for (int i = 0; i < 25; i++) {
        PCD_WriteRegister(mfrc, FIFODataReg, 0x00);
    }
    PCD_WriteRegister(mfrc, CommandReg, PCD_Mem); //Transfer the 25 bytes from FIFO to internal buffer
    //printf("Clearing of internal buffer complete\n\r");

    //Enable the self test by writing 09h to the AutoTestReg register.
    PCD_WriteRegister(mfrc, AutoTestReg, PCD_EnableSelfTest);
    //printf("Self test enable complete\n\r");

    //Write 00h to the FIFO buffer.
    PCD_WriteRegister(mfrc, FIFODataReg, 0x00);
    //printf("Written 0x00 to FIFO buffer\n\r");

    //Start the self test with the CalcCRC command.
    PCD_WriteRegister(mfrc, CommandReg, PCD_CalcCRC);
    //printf("Started self test with the CRC command\n\r");

    //The self test is initiated. Wait for completion
    bool self_test_complete = false;
    while (!self_test_complete) {
        uint8_t buf = PCD_ReadRegister(mfrc, FIFOLevelReg);
        //printf("%x\n\r", buf);
        if (buf >= 64) {
            self_test_complete = true;
        }
    }
    //printf("Self test completed\n\r");

    //Stop calculating CRC with idle command???

    //When the self test has completed, the FIFO buffer contains the version bytes.
    uint8_t result[64];
    for (int i = 0; i < 64; i++) {
        uint8_t buf = PCD_ReadRegister(mfrc, FIFODataReg);
        result[i] = buf;
    }
    //printf("Bytes copied to result array\n\r");

    //Check if the received bytes correspond to the versions.
    PCD_WriteRegister(mfrc, AutoTestReg, 0x00); //Disable self-test
    //printf("Disabled self test\n\r");

    /*printf("Self test result:\n\r");
    for (uint8_t i = 0; i < 64; i++) {
        printf("%x, ", result[i]);
        if (i % 10 == 0) printf("\n\r");
    } printf("\n\r"); */

    for (uint8_t i = 0; i < 64; i++) {
		if (result[i] != SELF_TEST_BYTES[i]) {
			return -1;
		}
	}

    return 0;

	}


/*******************************************************************************
* Functions for communicating with PICCs
*******************************************************************************/
/**
 * Executes the Transceive command.
 * CRC validation can only be done if backData and backLen are specified.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode PCD_TransceiveData(
	MFRC522Ptr_t mfrc,
	uint8_t *sendData,  ///< Pointer to the data to transfer to the FIFO.
	uint8_t sendLen,	///< Number of uint8_ts to transfer to the FIFO.
	uint8_t *backData,  ///< NULL or pointer to buffer if data should be read
						///back after executing the command.
	uint8_t *backLen,   ///< In: Max number of uint8_ts to write to *backData.
						///Out: The number of uint8_ts returned.
	uint8_t *validBits, ///< In/Out: The number of valid bits in the last
						///uint8_t. 0 for 8 valid bits. Default NULL.
	uint8_t rxAlign,	///< In: Defines the bit position in backData[0] for the
						///first bit received. Default 0.
	bool checkCRC ///< In: True => The last two uint8_ts of the response is
				  ///assumed to be a CRC_A that must be validated.
	) {
	//		 validBits=NULL;
	//		 rxAlign=0;
	//		 checkCRC=false;

	uint8_t waitIRq = 0x30; // RxIRq and IdleIRq
	return PCD_CommunicateWithPICC(mfrc, PCD_Transceive, waitIRq, sendData,
								   sendLen, backData, backLen, validBits,
								   rxAlign, checkCRC);
} // End PCD_TransceiveData()

/**
 * Transfers data to the MFRC522 FIFO, executes a command, waits for completion
 *and transfers data back from the FIFO.
 * CRC validation can only be done if backData and backLen are specified.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode PCD_CommunicateWithPICC(
	MFRC522Ptr_t mfrc,
	uint8_t command, ///< The command to execute. One of the PCD_Command enums.
	uint8_t waitIRq, ///< The bits in the ComIrqReg register that signals
					 ///successful completion of the command.
	uint8_t *sendData,  ///< Pointer to the data to transfer to the FIFO.
	uint8_t sendLen,	///< Number of uint8_ts to transfer to the FIFO.
	uint8_t *backData,  ///< NULL or pointer to buffer if data should be read
						///back after executing the command.
	uint8_t *backLen,   ///< In: Max number of uint8_ts to write to *backData.
						///Out: The number of uint8_ts returned.
	uint8_t *validBits, ///< In/Out: The number of valid bits in the last
						///uint8_t. 0 for 8 valid bits.
	uint8_t rxAlign,	///< In: Defines the bit position in backData[0] for the
						///first bit received. Default 0.
	bool checkCRC ///< In: True => The last two uint8_ts of the response is
				  ///assumed to be a CRC_A that must be validated.
	) {
	//		backData=NULL;
	//		backLen=NULL;
	//		validBits=NULL;
	//		rxAlign=0;
	//		checkCRC=false;

	uint8_t n, _validBits;
	unsigned int i;

	// Prepare values for BitFramingReg
	uint8_t txLastBits = validBits ? *validBits : 0;
	uint8_t bitFraming =
		(rxAlign << 4) + txLastBits; // RxAlign = BitFramingReg[6..4].
									 // TxLastBits = BitFramingReg[2..0]

	PCD_WriteRegister(mfrc, CommandReg, PCD_Idle); // Stop any active command.
	PCD_WriteRegister(mfrc, ComIrqReg,
					  0x7F); // Clear all seven interrupt request bits
	PCD_SetRegisterBitMask(mfrc, FIFOLevelReg,
						   0x80); // FlushBuffer = 1, FIFO initialization
	PCD_WriteNRegister(mfrc, FIFODataReg, sendLen,
					   sendData); // Write sendData to the FIFO
	PCD_WriteRegister(mfrc, BitFramingReg, bitFraming); // Bit adjustments
	PCD_WriteRegister(mfrc, CommandReg, command);		// Execute the command
	if (command == PCD_Transceive) {
		PCD_SetRegisterBitMask(
			mfrc, BitFramingReg,
			0x80); // StartSend=1, transmission of data starts
	}

	// Wait for the command to complete.
	// In PCD_Init() we set the TAuto flag in TModeReg. This means the timer
	// automatically starts when the PCD stops transmitting.
	// Each iteration of the do-while-loop takes 17.86�s.
	i = 2000;
	while (1) {
		n = PCD_ReadRegister(mfrc, ComIrqReg); // ComIrqReg[7..0] bits are: Set1
											   // TxIRq RxIRq IdleIRq HiAlertIRq
											   // LoAlertIRq ErrIRq TimerIRq
		if (n & waitIRq) { // One of the interrupts that signal success has been
						   // set.
			break;
		}
		if (n & 0x01) { // Timer interrupt - nothing received in 25ms
			return STATUS_TIMEOUT;
		}
		if (--i == 0) { // The emergency break. If all other conditions fail we
						// will eventually terminate on this one after 35.7ms.
						// Communication with the MFRC522 might be down.
			return STATUS_TIMEOUT;
		}
	}

	// Stop now if any errors except collisions were detected.
	uint8_t errorRegValue =
		PCD_ReadRegister(mfrc, ErrorReg); // ErrorReg[7..0] bits are: WrErr
										  // TempErr reserved BufferOvfl CollErr
										  // CRCErr ParityErr ProtocolErr
	if (errorRegValue & 0x13) {			  // BufferOvfl ParityErr ProtocolErr
		return STATUS_ERROR;
	}

	// If the caller wants data back, get it from the MFRC522.
	if (backData && backLen) {
		n = PCD_ReadRegister(mfrc,
							 FIFOLevelReg); // Number of uint8_ts in the FIFO
		if (n > *backLen) {
			return STATUS_NO_ROOM;
		}
		*backLen = n; // Number of uint8_ts returned
		PCD_ReadNRegister(mfrc, FIFODataReg, n, backData,
						  rxAlign); // Get received data from FIFO
		_validBits = PCD_ReadRegister(mfrc, ControlReg) &
					 0x07; // RxLastBits[2:0] indicates the number of valid bits
						   // in the last received uint8_t. If this value is
						   // 000b, the whole uint8_t is valid.
		if (validBits) {
			*validBits = _validBits;
		}
	}

	// Tell about collisions
	if (errorRegValue & 0x08) { // CollErr
		return STATUS_COLLISION;
	}

	// Perform CRC_A validation if requested.
	if (backData && backLen && checkCRC) {
		// In this case a MIFARE Classic NAK is not OK.
		if (*backLen == 1 && _validBits == 4) {
			return STATUS_MIFARE_NACK;
		}
		// We need at least the CRC_A value and all 8 bits of the last uint8_t
		// must be received.
		if (*backLen < 2 || _validBits != 0) {
			return STATUS_CRC_WRONG;
		}
		// Verify CRC_A - do our own calculation and store the control in
		// controlBuffer.
		uint8_t controlBuffer[2];
		StatusCode status = PCD_CalculateCRC(mfrc, &backData[0], *backLen - 2,
											 &controlBuffer[0]);
		if (status != STATUS_OK) {
			return status;
		}
		if ((backData[*backLen - 2] != controlBuffer[0]) ||
			(backData[*backLen - 1] != controlBuffer[1])) {
			return STATUS_CRC_WRONG;
		}
	}

	return STATUS_OK;
} // End PCD_CommunicateWithPICC()

/**
 * Transmits a REQuest command, Type A. Invites PICCs in state IDLE to go to
 *READY and prepare for anticollision or selection. 7 bit frame.
 * Beware: When two PICCs are in the field at the same time I often get
 *STATUS_TIMEOUT - probably due do bad antenna design.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode PICC_RequestA(
	MFRC522Ptr_t mfrc,
	uint8_t *
		bufferATQA,		///< The buffer to store the ATQA (Answer to request) in
	uint8_t *bufferSize ///< Buffer size, at least two uint8_ts. Also number of
						///uint8_ts returned if STATUS_OK.
	) {
	return PICC_REQA_or_WUPA(mfrc, PICC_CMD_REQA, bufferATQA, bufferSize);
} // End PICC_RequestA()

/**
 * Transmits a Wake-UP command, Type A. Invites PICCs in state IDLE and HALT to
 *go to READY(*) and prepare for anticollision or selection. 7 bit frame.
 * Beware: When two PICCs are in the field at the same time I often get
 *STATUS_TIMEOUT - probably due do bad antenna design.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode PICC_WakeupA(
	MFRC522Ptr_t mfrc,
	uint8_t *
		bufferATQA,		///< The buffer to store the ATQA (Answer to request) in
	uint8_t *bufferSize ///< Buffer size, at least two uint8_ts. Also number of
						///uint8_ts returned if STATUS_OK.
	) {
	return PICC_REQA_or_WUPA(mfrc, PICC_CMD_WUPA, bufferATQA, bufferSize);
} // End PICC_WakeupA()

/**
 * Transmits REQA or WUPA commands.
 * Beware: When two PICCs are in the field at the same time I often get
 *STATUS_TIMEOUT - probably due do bad antenna design.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode PICC_REQA_or_WUPA(
	MFRC522Ptr_t mfrc,
	uint8_t command, ///< The command to send - PICC_CMD_REQA or PICC_CMD_WUPA
	uint8_t *
		bufferATQA,		///< The buffer to store the ATQA (Answer to request) in
	uint8_t *bufferSize ///< Buffer size, at least two uint8_ts. Also number of
						///uint8_ts returned if STATUS_OK.
	) {
	uint8_t validBits;
	StatusCode status;

	if (bufferATQA == NULL ||
		*bufferSize < 2) { // The ATQA response is 2 uint8_ts long.
		return STATUS_NO_ROOM;
	}
	PCD_ClearRegisterBitMask(mfrc, CollReg, 0x80); // ValuesAfterColl=1 => Bits
												   // received after collision
												   // are cleared.
	validBits = 7; // For REQA and WUPA we need the short frame format -
				   // transmit only 7 bits of the last (and only) uint8_t.
				   // TxLastBits = BitFramingReg[2..0]
	status = PCD_TransceiveData(mfrc, &command, 1, bufferATQA, bufferSize,
								&validBits, 0, false);
	if (status != STATUS_OK) {
		return status;
	}
	if (*bufferSize != 2 || validBits != 0) { // ATQA must be exactly 16 bits.
		return STATUS_ERROR;
	}
	return STATUS_OK;
} // End PICC_REQA_or_WUPA()

/**
 * Transmits SELECT/ANTICOLLISION commands to select a single PICC.
 * Before calling this function the PICCs must be placed in the READY(*) state
 *by calling PICC_RequestA() or PICC_WakeupA().
 * On success:
 *		- The chosen PICC is in state ACTIVE(*) and all other PICCs have returned
 *to state IDLE/HALT. (Figure 7 of the ISO/IEC 14443-3 draft.)
 *		- The UID size and value of the chosen PICC is returned in *uid along with
 *the SAK.
 *
 * A PICC UID consists of 4, 7 or 10 uint8_ts.
 * Only 4 uint8_ts can be specified in a SELECT command, so for the longer UIDs
 *two or three iterations are used:
 *		UID size	Number of UID uint8_ts		Cascade levels		Example of
 *PICC
 *		========	===================		==============		===============
 *		single				 4						1				MIFARE
 *Classic
 *		double				 7						2				MIFARE
 *Ultralight
 *		triple				10						3				Not currently in
 *use?
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode PICC_Select(MFRC522Ptr_t mfrc,
					   Uid *uid, ///< Pointer to Uid struct. Normally output,
								 ///but can also be used to supply a known UID.
					   uint8_t validBits ///< The number of known UID bits
										 ///supplied in *uid. Normally 0. If set
										 ///you must also supply uid->size.
					   ) {
	//		validBits=0;

	bool uidComplete;
	bool selectDone;
	bool useCascadeTag;
	uint8_t cascadeLevel = 1;
	StatusCode result;
	uint8_t count;
	uint8_t index;
	uint8_t uidIndex; // The first index in uid->uiduint8_t[] that is used in
					  // the current Cascade Level.
	int8_t currentLevelKnownBits; // The number of known UID bits in the current
								  // Cascade Level.
	uint8_t buffer[9];  // The SELECT/ANTICOLLISION commands uses a 7 uint8_t
						// standard frame + 2 uint8_ts CRC_A
	uint8_t bufferUsed; // The number of uint8_ts used in the buffer, ie the
						// number of uint8_ts to transfer to the FIFO.
	uint8_t rxAlign; // Used in BitFramingReg. Defines the bit position for the
					 // first bit received.
	uint8_t txLastBits; // Used in BitFramingReg. The number of valid bits in
						// the last transmitted uint8_t.
	uint8_t *responseBuffer;
	uint8_t responseLength;

	// Description of buffer structure:
	//		uint8_t 0: SEL				Indicates the Cascade Level: PICC_CMD_SEL_CL1,
	//PICC_CMD_SEL_CL2 or PICC_CMD_SEL_CL3
	//		uint8_t 1: NVB					Number of Valid Bits (in complete command, not
	//just the UID): High nibble: complete uint8_ts, Low nibble: Extra bits.
	//		uint8_t 2: UID-data or CT		See explanation below. CT means Cascade
	//Tag.
	//		uint8_t 3: UID-data
	//		uint8_t 4: UID-data
	//		uint8_t 5: UID-data
	//		uint8_t 6: BCC					Block Check Character - XOR of uint8_ts
	//2-5
	//		uint8_t 7: CRC_A
	//		uint8_t 8: CRC_A
	// The BCC and CRC_A are only transmitted if we know all the UID bits of the
	// current Cascade Level.
	//
	// Description of uint8_ts 2-5: (Section 6.5.4 of the ISO/IEC 14443-3 draft:
	// UID contents and cascade levels)
	//		UID size	Cascade level	uint8_t2	uint8_t3	uint8_t4
	//uint8_t5
	//		========	=============	=====	=====	=====	=====
	//		 4 uint8_ts		1			uid0	uid1	uid2	uid3
	//		 7 uint8_ts		1			CT		uid0	uid1	uid2
	//						2			uid3	uid4	uid5	uid6
	//		10 uint8_ts		1			CT		uid0	uid1	uid2
	//						2			CT		uid3	uid4	uid5
	//						3			uid6	uid7	uid8	uid9

	// Sanity checks
	if (validBits > 80) {
		return STATUS_INVALID;
	}

	// Prepare MFRC522
	PCD_ClearRegisterBitMask(mfrc, CollReg, 0x80); // ValuesAfterColl=1 => Bits
												   // received after collision
												   // are cleared.

	// Repeat Cascade Level loop until we have a complete UID.
	uidComplete = false;
	while (!uidComplete) {
		// Set the Cascade Level in the SEL uint8_t, find out if we need to use
		// the Cascade Tag in uint8_t 2.
		switch (cascadeLevel) {
		case 1:
			buffer[0] = PICC_CMD_SEL_CL1;
			uidIndex = 0;
			useCascadeTag =
				validBits &&
				uid->size >
					4; // When we know that the UID has more than 4 uint8_ts
			break;

		case 2:
			buffer[0] = PICC_CMD_SEL_CL2;
			uidIndex = 3;
			useCascadeTag =
				validBits &&
				uid->size >
					7; // When we know that the UID has more than 7 uint8_ts
			break;

		case 3:
			buffer[0] = PICC_CMD_SEL_CL3;
			uidIndex = 6;
			useCascadeTag = false; // Never used in CL3.
			break;

		default:
			return STATUS_INTERNAL_ERROR;
			break;
		}

		// How many UID bits are known in this Cascade Level?
		currentLevelKnownBits = validBits - (8 * uidIndex);
		if (currentLevelKnownBits < 0) {
			currentLevelKnownBits = 0;
		}
		// Copy the known bits from uid->uiduint8_t[] to buffer[]
		index = 2; // destination index in buffer[]
		if (useCascadeTag) {
			buffer[index++] = PICC_CMD_CT;
		}
		uint8_t uint8_tsToCopy =
			currentLevelKnownBits / 8 +
			(currentLevelKnownBits % 8 ? 1 : 0); // The number of uint8_ts
												 // needed to represent the
												 // known bits for this level.
		if (uint8_tsToCopy) {
			uint8_t maxuint8_ts =
				useCascadeTag ? 3 : 4; // Max 4 uint8_ts in each Cascade Level.
									   // Only 3 left if we use the Cascade Tag
			if (uint8_tsToCopy > maxuint8_ts) {
				uint8_tsToCopy = maxuint8_ts;
			}
			for (count = 0; count < uint8_tsToCopy; count++) {
				buffer[index++] = uid->uidByte[uidIndex + count];
			}
		}
		// Now that the data has been copied we need to include the 8 bits in CT
		// in currentLevelKnownBits
		if (useCascadeTag) {
			currentLevelKnownBits += 8;
		}

		// Repeat anti collision loop until we can transmit all UID bits + BCC
		// and receive a SAK - max 32 iterations.
		selectDone = false;
		while (!selectDone) {
			// Find out how many bits and uint8_ts to send and receive.
			if (currentLevelKnownBits >= 32) { // All UID bits in this Cascade
											   // Level are known. This is a
											   // SELECT.
				// printf(F("SELECT: currentLevelKnownBits="));
				// printf(currentLevelKnownBits, DEC);
				buffer[1] =
					0x70; // NVB - Number of Valid Bits: Seven whole uint8_ts
				// Calculate BCC - Block Check Character
				buffer[6] = buffer[2] ^ buffer[3] ^ buffer[4] ^ buffer[5];
				// Calculate CRC_A
				result = PCD_CalculateCRC(mfrc, buffer, 7, &buffer[7]);
				if (result != STATUS_OK) {
					return result;
				}
				txLastBits = 0; // 0 => All 8 bits are valid.
				bufferUsed = 9;
				// Store response in the last 3 uint8_ts of buffer (BCC and
				// CRC_A - not needed after tx)
				responseBuffer = &buffer[6];
				responseLength = 3;
			} else { // This is an ANTICOLLISION.
				// printf(F("ANTICOLLISION: currentLevelKnownBits="));
				// printf(currentLevelKnownBits, DEC);
				txLastBits = currentLevelKnownBits % 8;
				count = currentLevelKnownBits /
						8;		   // Number of whole uint8_ts in the UID part.
				index = 2 + count; // Number of whole uint8_ts: SEL + NVB + UIDs
				buffer[1] =
					(index << 4) + txLastBits; // NVB - Number of Valid Bits
				bufferUsed = index + (txLastBits ? 1 : 0);
				// Store response in the unused part of buffer
				responseBuffer = &buffer[index];
				responseLength = sizeof(buffer) - index;
			}

			// Set bit adjustments
			rxAlign = txLastBits; // Having a separate variable is overkill. But
								  // it makes the next line easier to read.
			PCD_WriteRegister(mfrc, BitFramingReg,
							  (rxAlign << 4) +
								  txLastBits); // RxAlign = BitFramingReg[6..4].
											   // TxLastBits =
											   // BitFramingReg[2..0]

			// Transmit the buffer and receive the response.
			result = PCD_TransceiveData(mfrc, buffer, bufferUsed,
										responseBuffer, &responseLength,
										&txLastBits, rxAlign, false);
			if (result == STATUS_COLLISION) { // More than one PICC in the field
											  // => collision.
				uint8_t valueOfCollReg = PCD_ReadRegister(
					mfrc, CollReg); // CollReg[7..0] bits are: ValuesAfterColl
									// reserved CollPosNotValid CollPos[4:0]
				if (valueOfCollReg & 0x20) { // CollPosNotValid
					return STATUS_COLLISION; // Without a valid collision
											 // position we cannot continue
				}
				uint8_t collisionPos =
					valueOfCollReg & 0x1F; // Values 0-31, 0 means bit 32.
				if (collisionPos == 0) {
					collisionPos = 32;
				}
				if (collisionPos <=
					currentLevelKnownBits) { // No progress - should not happen
					return STATUS_INTERNAL_ERROR;
				}
				// Choose the PICC with the bit set.
				currentLevelKnownBits = collisionPos;
				count = (currentLevelKnownBits - 1) % 8; // The bit to modify
				index = 1 + (currentLevelKnownBits / 8) +
						(count ? 1 : 0); // First uint8_t is index 0.
				buffer[index] |= (1 << count);
			} else if (result != STATUS_OK) {
				return result;
			} else {							   // STATUS_OK
				if (currentLevelKnownBits >= 32) { // This was a SELECT.
					selectDone = true;			   // No more anticollision
					// We continue below outside the while.
				} else { // This was an ANTICOLLISION.
					// We now have all 32 bits of the UID in this Cascade Level
					currentLevelKnownBits = 32;
					// Run loop again to do the SELECT.
				}
			}
		} // End of while (!selectDone)

		// We do not check the CBB - it was constructed by us above.

		// Copy the found UID uint8_ts from buffer[] to uid->uiduint8_t[]
		index = (buffer[2] == PICC_CMD_CT) ? 3 : 2; // source index in buffer[]
		uint8_tsToCopy = (buffer[2] == PICC_CMD_CT) ? 3 : 4;
		for (count = 0; count < uint8_tsToCopy; count++) {
			uid->uidByte[uidIndex + count] = buffer[index++];
		}

		// Check response SAK (Select Acknowledge)
		if (responseLength != 3 ||
			txLastBits !=
				0) { // SAK must be exactly 24 bits (1 uint8_t + CRC_A).
			return STATUS_ERROR;
		}
		// Verify CRC_A - do our own calculation and store the control in
		// buffer[2..3] - those uint8_ts are not needed anymore.
		result = PCD_CalculateCRC(mfrc, responseBuffer, 1, &buffer[2]);
		if (result != STATUS_OK) {
			return result;
		}
		if ((buffer[2] != responseBuffer[1]) ||
			(buffer[3] != responseBuffer[2])) {
			return STATUS_CRC_WRONG;
		}
		if (responseBuffer[0] &
			0x04) { // Cascade bit set - UID not complete yes
			cascadeLevel++;
		} else {
			uidComplete = true;
			uid->sak = responseBuffer[0];
		}
	} // End of while (!uidComplete)

	// Set correct uid->size
	uid->size = 3 * cascadeLevel + 1;

	return STATUS_OK;
} // End PICC_Select()

/**
 * Instructs a PICC in state ACTIVE(*) to go to state HALT.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode PICC_HaltA(MFRC522Ptr_t mfrc) {
	StatusCode result;
	uint8_t buffer[4];

	// Build command buffer
	buffer[0] = PICC_CMD_HLTA;
	buffer[1] = 0;
	// Calculate CRC_A
	result = PCD_CalculateCRC(mfrc, buffer, 2, &buffer[2]);
	if (result != STATUS_OK) {
		return result;
	}

	// Send the command.
	// The standard says:
	//		If the PICC responds with any modulation during a period of 1 ms after
	//the end of the frame containing the
	//		HLTA command, this response shall be interpreted as 'not
	//acknowledge'.
	// We interpret that this way: Only STATUS_TIMEOUT is a success.
	result = PCD_TransceiveData(mfrc, buffer, sizeof(buffer), NULL, 0, NULL, 0,
								false);
	if (result == STATUS_TIMEOUT) {
		return STATUS_OK;
	}
	if (result == STATUS_OK) { // That is ironically NOT ok in this case ;-)
		return STATUS_ERROR;
	}
	return result;
} // End PICC_HaltA()

/*******************************************************************************
*Functions for communicating with MIFARE PICCs
*******************************************************************************/

/**
 * Executes the MFRC522 MFAuthent command.
 * This command manages MIFARE authentication to enable a secure communication
 *to any MIFARE Mini, MIFARE 1K and MIFARE 4K card.
 * The authentication is described in the MFRC522 datasheet section 10.3.1.9 and
 *http://www.nxp.com/documents/data_sheet/MF1S503x.pdf section 10.1.
 * For use with MIFARE Classic PICCs.
 * The PICC must be selected - ie in state ACTIVE(*) - before calling this
 *function.
 * Remember to call PCD_StopCrypto1() after communicating with the authenticated
 *PICC - otherwise no new communications can start.
 *
 * All keys are set to FFFFFFFFFFFFh at chip delivery.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise. Probably STATUS_TIMEOUT
 *if you supply the wrong key.
 */
StatusCode PCD_Authenticate(
	MFRC522Ptr_t mfrc,
	uint8_t command,   ///< PICC_CMD_MF_AUTH_KEY_A or PICC_CMD_MF_AUTH_KEY_B
	uint8_t blockAddr, ///< The block number. See numbering in the comments in
					   ///the .h file.
	MIFARE_Key *key,   ///< Pointer to the Crypteo1 key to use (6 uint8_ts)
	Uid *
		uid ///< Pointer to Uid struct. The first 4 uint8_ts of the UID is used.
	) {
	uint8_t waitIRq = 0x10; // IdleIRq

	// Build command buffer
	uint8_t sendData[12];
	sendData[0] = command;
	sendData[1] = blockAddr;
	for (uint8_t i = 0; i < MF_KEY_SIZE; i++) { // 6 key uint8_ts
		sendData[2 + i] = key->keybyte[i];
	}
	for (uint8_t i = 0; i < 4; i++) { // The first 4 uint8_ts of the UID
		sendData[8 + i] = uid->uidByte[i];
	}

	// Start the authentication.
	return PCD_CommunicateWithPICC(mfrc, PCD_MFAuthent, waitIRq, &sendData[0],
								   sizeof(sendData), NULL, 0, 0, 0, false);
} // End PCD_Authenticate()

/**
 * Used to exit the PCD from its authenticated state.
 * Remember to call this function after communicating with an authenticated PICC
 * - otherwise no new communications can start.
 */
void PCD_StopCrypto1(MFRC522Ptr_t mfrc) {
	// Clear MFCrypto1On bit
	PCD_ClearRegisterBitMask(mfrc, Status2Reg, 0x08); // Status2Reg[7..0] bits
													  // are: TempSensClear
													  // I2CForceHS reserved
													  // reserved MFCrypto1On
													  // ModemState[2:0]
} // End PCD_StopCrypto1()

/**
 * Reads 16 uint8_ts (+ 2 uint8_ts CRC_A) from the active PICC.
 *
 * For MIFARE Classic the sector containing the block must be authenticated
 *before calling this function.
 *
 * For MIFARE Ultralight only addresses 00h to 0Fh are decoded.
 * The MF0ICU1 returns a NAK for higher addresses.
 * The MF0ICU1 responds to the READ command by sending 16 uint8_ts starting from
 *the page address defined by the command argument.
 * For example; if blockAddr is 03h then pages 03h, 04h, 05h, 06h are returned.
 * A roll-back is implemented: If blockAddr is 0Eh, then the contents of pages
 *0Eh, 0Fh, 00h and 01h are returned.
 *
 * The buffer must be at least 18 uint8_ts because a CRC_A is also returned.
 * Checks the CRC_A before returning STATUS_OK.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode MIFARE_Read(MFRC522Ptr_t mfrc,
					   uint8_t blockAddr, ///< MIFARE Classic: The block
										  ///(0-0xff) number. MIFARE Ultralight:
										  ///The first page to return data from.
					   uint8_t *buffer,   ///< The buffer to store the data in
					   uint8_t *bufferSize ///< Buffer size, at least 18
										   ///uint8_ts. Also number of uint8_ts
										   ///returned if STATUS_OK.
					   ) {
	StatusCode result;

	// Sanity check
	if (buffer == NULL || *bufferSize < 18) {
		return STATUS_NO_ROOM;
	}

	// Build command buffer
	buffer[0] = PICC_CMD_MF_READ;
	buffer[1] = blockAddr;
	// Calculate CRC_A
	result = PCD_CalculateCRC(mfrc, buffer, 2, &buffer[2]);
	if (result != STATUS_OK) {
		return result;
	}

	// Transmit the buffer and receive the response, validate CRC_A.
	return PCD_TransceiveData(mfrc, buffer, 4, buffer, bufferSize, NULL, 0,
							  true);
} // End MIFARE_Read()

/**
 * Writes 16 uint8_ts to the active PICC.
 *
 * For MIFARE Classic the sector containing the block must be authenticated
 *before calling this function.
 *
 * For MIFARE Ultralight the operation is called "COMPATIBILITY WRITE".
 * Even though 16 uint8_ts are transferred to the Ultralight PICC, only the
 *least significant 4 uint8_ts (uint8_ts 0 to 3)
 * are written to the specified address. It is recommended to set the remaining
 *uint8_ts 04h to 0Fh to all logic 0.
 * *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode
MIFARE_Write(MFRC522Ptr_t mfrc,
			 uint8_t blockAddr, ///< MIFARE Classic: The block (0-0xff) number.
								///MIFARE Ultralight: The page (2-15) to write
								///to.
			 uint8_t *buffer,   ///< The 16 uint8_ts to write to the PICC
			 uint8_t bufferSize ///< Buffer size, must be at least 16 uint8_ts.
								///Exactly 16 uint8_ts are written.
			 ) {
	StatusCode result;

	// Sanity check
	if (buffer == NULL || bufferSize < 16) {
		return STATUS_INVALID;
	}

	// Mifare Classic protocol requires two communications to perform a write.
	// Step 1: Tell the PICC we want to write to block blockAddr.
	uint8_t cmdBuffer[2];
	cmdBuffer[0] = PICC_CMD_MF_WRITE;
	cmdBuffer[1] = blockAddr;
	result = PCD_MIFARE_Transceive(
		mfrc, cmdBuffer, 2,
		false); // Adds CRC_A and checks that the response is MF_ACK.
	if (result != STATUS_OK) {
		return result;
	}

	// Step 2: Transfer the data
	result = PCD_MIFARE_Transceive(
		mfrc, buffer, bufferSize,
		false); // Adds CRC_A and checks that the response is MF_ACK.
	if (result != STATUS_OK) {
		return result;
	}

	return STATUS_OK;
} // End MIFARE_Write()

/**
 * Writes a 4 uint8_t page to the active MIFARE Ultralight PICC.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode MIFARE_Ultralight_Write(
	MFRC522Ptr_t mfrc,
	uint8_t page,	  ///< The page (2-15) to write to.
	uint8_t *buffer,   ///< The 4 uint8_ts to write to the PICC
	uint8_t bufferSize ///< Buffer size, must be at least 4 uint8_ts. Exactly 4
					   ///uint8_ts are written.
	) {
	StatusCode result;

	// Sanity check
	if (buffer == NULL || bufferSize < 4) {
		return STATUS_INVALID;
	}

	// Build commmand buffer
	uint8_t cmdBuffer[6];
	cmdBuffer[0] = PICC_CMD_UL_WRITE;
	cmdBuffer[1] = page;
	memcpy(&cmdBuffer[2], buffer, 4);

	// Perform the write
	result = PCD_MIFARE_Transceive(
		mfrc, cmdBuffer, 6,
		false); // Adds CRC_A and checks that the response is MF_ACK.
	if (result != STATUS_OK) {
		return result;
	}
	return STATUS_OK;
} // End MIFARE_Ultralight_Write()

/**
 * MIFARE Decrement subtracts the delta from the value of the addressed block,
 *and stores the result in a volatile memory.
 * For MIFARE Classic only. The sector containing the block must be
 *authenticated before calling this function.
 * Only for blocks in "value block" mode, ie with access bits [C1 C2 C3] = [110]
 *or [001].
 * Use MIFARE_Transfer() to store the result in a block.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode MIFARE_Decrement(
	MFRC522Ptr_t mfrc,
	uint8_t blockAddr, ///< The block (0-0xff) number.
	long delta ///< This number is subtracted from the value of block blockAddr.
	) {
	return MIFARE_TwoStepHelper(mfrc, PICC_CMD_MF_DECREMENT, blockAddr, delta);
} // End MIFARE_Decrement()

/**
 * MIFARE Increment adds the delta to the value of the addressed block, and
 *stores the result in a volatile memory.
 * For MIFARE Classic only. The sector containing the block must be
 *authenticated before calling this function.
 * Only for blocks in "value block" mode, ie with access bits [C1 C2 C3] = [110]
 *or [001].
 * Use MIFARE_Transfer() to store the result in a block.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode MIFARE_Increment(
	MFRC522Ptr_t mfrc,
	uint8_t blockAddr, ///< The block (0-0xff) number.
	long delta ///< This number is added to the value of block blockAddr.
	) {
	return MIFARE_TwoStepHelper(mfrc, PICC_CMD_MF_INCREMENT, blockAddr, delta);
} // End MIFARE_Increment()

/**
 * MIFARE Restore copies the value of the addressed block into a volatile
 *memory.
 * For MIFARE Classic only. The sector containing the block must be
 *authenticated before calling this function.
 * Only for blocks in "value block" mode, ie with access bits [C1 C2 C3] = [110]
 *or [001].
 * Use MIFARE_Transfer() to store the result in a block.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode MIFARE_Restore(MFRC522Ptr_t mfrc,
						  uint8_t blockAddr ///< The block (0-0xff) number.
						  ) {
	// The datasheet describes Restore as a two step operation, but does not
	// explain what data to transfer in step 2.
	// Doing only a single step does not work, so I chose to transfer 0L in step
	// two.
	return MIFARE_TwoStepHelper(mfrc, PICC_CMD_MF_RESTORE, blockAddr, 0L);
} // End MIFARE_Restore()

/**
 * Helper function for the two-step MIFARE Classic protocol operations
 *Decrement, Increment and Restore.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode
MIFARE_TwoStepHelper(MFRC522Ptr_t mfrc,
					 uint8_t command,   ///< The command to use
					 uint8_t blockAddr, ///< The block (0-0xff) number.
					 long data			///< The data to transfer in step 2
					 ) {
	StatusCode result;
	uint8_t cmdBuffer[2]; // We only need room for 2 uint8_ts.

	// Step 1: Tell the PICC the command and block address
	cmdBuffer[0] = command;
	cmdBuffer[1] = blockAddr;
	result = PCD_MIFARE_Transceive(
		mfrc, cmdBuffer, 2,
		false); // Adds CRC_A and checks that the response is MF_ACK.
	if (result != STATUS_OK) {
		return result;
	}

	// Step 2: Transfer the data
	result = PCD_MIFARE_Transceive(
		mfrc, (uint8_t *)&data, 4,
		true); // Adds CRC_A and accept timeout as success.
	if (result != STATUS_OK) {
		return result;
	}

	return STATUS_OK;
} // End MIFARE_TwoStepHelper()

/**
 * MIFARE Transfer writes the value stored in the volatile memory into one
 *MIFARE Classic block.
 * For MIFARE Classic only. The sector containing the block must be
 *authenticated before calling this function.
 * Only for blocks in "value block" mode, ie with access bits [C1 C2 C3] = [110]
 *or [001].
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode MIFARE_Transfer(MFRC522Ptr_t mfrc,
						   uint8_t blockAddr ///< The block (0-0xff) number.
						   ) {
	StatusCode result;
	uint8_t cmdBuffer[2]; // We only need room for 2 uint8_ts.

	// Tell the PICC we want to transfer the result into block blockAddr.
	cmdBuffer[0] = PICC_CMD_MF_TRANSFER;
	cmdBuffer[1] = blockAddr;
	result = PCD_MIFARE_Transceive(
		mfrc, cmdBuffer, 2,
		false); // Adds CRC_A and checks that the response is MF_ACK.
	if (result != STATUS_OK) {
		return result;
	}
	return STATUS_OK;
} // End MIFARE_Transfer()

/**
 * Helper routine to read the current value from a Value Block.
 *
 * Only for MIFARE Classic and only for blocks in "value block" mode, that
 * is: with access bits [C1 C2 C3] = [110] or [001]. The sector containing
 * the block must be authenticated before calling this function.
 *
 * @param[in]   blockAddr   The block (0x00-0xff) number.
 * @param[out]  value       Current value of the Value Block.
 * @return STATUS_OK on success, STATUS_??? otherwise.
  */
StatusCode MIFARE_GetValue(MFRC522Ptr_t mfrc, uint8_t blockAddr, long *value) {
	StatusCode status;
	uint8_t buffer[18];
	uint8_t size = sizeof(buffer);

	// Read the block
	status = MIFARE_Read(mfrc, blockAddr, buffer, &size);
	if (status == STATUS_OK) {
		// Extract the value
		//			*value = (long(buffer[3])<<24) | (long(buffer[2])<<16) |
		//(long(buffer[1])<<8) | long(buffer[0]);
		//			long l_0 = buffer[0];
		//			long l_8 = buffer[1]<<8;
		//			long l_16 = buffer[2]<<16;
		//			long l_24 = buffer[3]<<24;
		//			*value =l_24 | l_16 | l_8 | l_0;
		*value = ((long)(buffer[3]) << 24) | ((long)(buffer[2]) << 16) |
				 ((long)(buffer[1]) << 8) | (long)(buffer[0]);
	}
	return status;
} // End MIFARE_GetValue()

/**
 * Helper routine to write a specific value into a Value Block.
 *
 * Only for MIFARE Classic and only for blocks in "value block" mode, that
 * is: with access bits [C1 C2 C3] = [110] or [001]. The sector containing
 * the block must be authenticated before calling this function.
 *
 * @param[in]   blockAddr   The block (0x00-0xff) number.
 * @param[in]   value       New value of the Value Block.
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode MIFARE_SetValue(MFRC522Ptr_t mfrc, uint8_t blockAddr, long value) {
	uint8_t buffer[18];

	// Translate the long into 4 uint8_ts; repeated 2x in value block
	buffer[0] = buffer[8] = (value & 0xFF);
	buffer[1] = buffer[9] = (value & 0xFF00) >> 8;
	buffer[2] = buffer[10] = (value & 0xFF0000) >> 16;
	buffer[3] = buffer[11] = (value & 0xFF000000) >> 24;
	// Inverse 4 uint8_ts also found in value block
	buffer[4] = ~buffer[0];
	buffer[5] = ~buffer[1];
	buffer[6] = ~buffer[2];
	buffer[7] = ~buffer[3];
	// Address 2x with inverse address 2x
	buffer[12] = buffer[14] = blockAddr;
	buffer[13] = buffer[15] = ~blockAddr;

	// Write the whole data block
	return MIFARE_Write(mfrc, blockAddr, buffer, 16);
} // End MIFARE_SetValue()

/**
 * Authenticate with a NTAG216.
 *
 * Only for NTAG216. First implemented by Gargantuanman.
 *
 * @param[in]   passWord   password.
 * @param[in]   pACK       result success???.
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode PCD_NTAG216_AUTH(MFRC522Ptr_t mfrc, uint8_t *passWord,
							uint8_t pACK[]) // Authenticate with 32bit password
{
	StatusCode result;
	uint8_t cmdBuffer[18]; // We need room for 16 uint8_ts data and 2 uint8_ts
						   // CRC_A.

	cmdBuffer[0] = 0x1B; // Comando de autentificacion

	for (uint8_t i = 0; i < 4; i++)
		cmdBuffer[i + 1] = passWord[i];

	result = PCD_CalculateCRC(mfrc, cmdBuffer, 5, &cmdBuffer[5]);

	if (result != STATUS_OK) {
		return result;
	}

	// Transceive the data, store the reply in cmdBuffer[]
	uint8_t waitIRq = 0x30; // RxIRq and IdleIRq
	uint8_t cmdBufferSize = sizeof(cmdBuffer);
	uint8_t validBits = 0;
	uint8_t rxlength = 5;
	result =
		PCD_CommunicateWithPICC(mfrc, PCD_Transceive, waitIRq, cmdBuffer, 7,
								cmdBuffer, &rxlength, &validBits, 0, false);

	pACK[0] = cmdBuffer[0];
	pACK[1] = cmdBuffer[1];

	if (result != STATUS_OK) {
		return result;
	}

	return STATUS_OK;
} // End PCD_NTAG216_AUTH()

/*******************************************************************************
* Support functions
*******************************************************************************/

/**
 * Wrapper for MIFARE protocol communication.
 * Adds CRC_A, executes the Transceive command and checks that the response is
 *MF_ACK or a timeout.
 *
 * @return STATUS_OK on success, STATUS_??? otherwise.
 */
StatusCode
PCD_MIFARE_Transceive(MFRC522Ptr_t mfrc,
					  uint8_t *sendData, ///< Pointer to the data to transfer to
										 ///the FIFO. Do NOT include the CRC_A.
					  uint8_t sendLen,   ///< Number of uint8_ts in sendData.
					  bool acceptTimeout ///< True => A timeout is also success
					  ) {
	//		acceptTimeout = false;

	StatusCode result;
	uint8_t cmdBuffer[18]; // We need room for 16 uint8_ts data and 2 uint8_ts
						   // CRC_A.

	// Sanity check
	if (sendData == NULL || sendLen > 16) {
		return STATUS_INVALID;
	}

	// Copy sendData[] to cmdBuffer[] and add CRC_A
	memcpy(cmdBuffer, sendData, sendLen);
	result = PCD_CalculateCRC(mfrc, cmdBuffer, sendLen, &cmdBuffer[sendLen]);
	if (result != STATUS_OK) {
		return result;
	}
	sendLen += 2;

	// Transceive the data, store the reply in cmdBuffer[]
	uint8_t waitIRq = 0x30; // RxIRq and IdleIRq
	uint8_t cmdBufferSize = sizeof(cmdBuffer);
	uint8_t validBits = 0;
	result = PCD_CommunicateWithPICC(mfrc, PCD_Transceive, waitIRq, cmdBuffer,
									 sendLen, cmdBuffer, &cmdBufferSize,
									 &validBits, 0, false);
	if (acceptTimeout && result == STATUS_TIMEOUT) {
		return STATUS_OK;
	}
	if (result != STATUS_OK) {
		return result;
	}
	// The PICC must reply with a 4 bit ACK
	if (cmdBufferSize != 1 || validBits != 4) {
		return STATUS_ERROR;
	}
	if (cmdBuffer[0] != MF_ACK) {
		return STATUS_MIFARE_NACK;
	}
	return STATUS_OK;
} // End PCD_MIFARE_Transceive()

/**
 * Returns const char pointer to a status code name.
 *
 * @return const char *
 */
const char *GetStatusCodeName(StatusCode code ///< One of theStatusCode enums.
							  ) {
	switch (code) {
	case STATUS_OK:
		return "Success.";
	case STATUS_ERROR:
		return "Error in communication.";
	case STATUS_COLLISION:
		return "Collision detected.";
	case STATUS_TIMEOUT:
		return "Timeout in communication.";
	case STATUS_NO_ROOM:
		return "A buffer is not big enough.";
	case STATUS_INTERNAL_ERROR:
		return "Internal error in the code. Should not happen.";
	case STATUS_INVALID:
		return "Invalid argument.";
	case STATUS_CRC_WRONG:
		return "The CRC_A does not match.";
	case STATUS_MIFARE_NACK:
		return "A MIFARE PICC responded with NAK.";
	default:
		return "Unknown error";
	}
} // End GetStatusCodeName()

/**
 * Translates the SAK (Select Acknowledge) to a PICC type.
 *
 * @return PICC_Type
 */
PICC_Type
PICC_GetType(uint8_t sak ///< The SAK uint8_t returned from PICC_Select().
			 ) {
	// http://www.nxp.com/documents/application_note/AN10833.pdf
	// 3.2 Coding of Select Acknowledge (SAK)
	// ignore 8-bit (iso14443 starts with LSBit = bit 1)
	// fixes wrong type for manufacturer Infineon
	// (http://nfc-tools.org/index.php?title=ISO14443A)
	sak &= 0x7F;
	switch (sak) {
	case 0x04:
		return PICC_TYPE_NOT_COMPLETE; // UID not complete
	case 0x09:
		return PICC_TYPE_MIFARE_MINI;
	case 0x08:
		return PICC_TYPE_MIFARE_1K;
	case 0x18:
		return PICC_TYPE_MIFARE_4K;
	case 0x00:
		return PICC_TYPE_MIFARE_UL;
	case 0x10:
	case 0x11:
		return PICC_TYPE_MIFARE_PLUS;
	case 0x01:
		return PICC_TYPE_TNP3XXX;
	case 0x20:
		return PICC_TYPE_ISO_14443_4;
	case 0x40:
		return PICC_TYPE_ISO_18092;
	default:
		return PICC_TYPE_UNKNOWN;
	}
} // End PICC_GetType()

/**
 * Returns const char pointer to the PICC type name.
 *
 * @return const char *
 */
const char *PICC_GetTypeName(PICC_Type piccType ///< One of the PICC_Type enums.
							 ) {
	switch (piccType) {
	case PICC_TYPE_ISO_14443_4:
		return "PICC compliant with ISO/IEC 14443-4";
	case PICC_TYPE_ISO_18092:
		return "PICC compliant with ISO/IEC 18092 (NFC)";
	case PICC_TYPE_MIFARE_MINI:
		return "MIFARE Mini, 320 bytes";
	case PICC_TYPE_MIFARE_1K:
		return "MIFARE 1KB";
	case PICC_TYPE_MIFARE_4K:
		return "MIFARE 4KB";
	case PICC_TYPE_MIFARE_UL:
		return "MIFARE Ultralight or Ultralight C";
	case PICC_TYPE_MIFARE_PLUS:
		return "MIFARE Plus";
	case PICC_TYPE_TNP3XXX:
		return "MIFARE TNP3XXX";
	case PICC_TYPE_NOT_COMPLETE:
		return "SAK indicates UID is not complete.";
	case PICC_TYPE_UNKNOWN:
	default:
		return "Unknown type";
	}
} // End PICC_GetTypeName()

/**
 * Dumps debug info about the connected PCD to Serial.
 * Shows all known firmware versions
 */
void PCD_DumpVersionToSerial(MFRC522Ptr_t mfrc) {
	char string[2];
	// Get the MFRC522 firmware version
	uint8_t v = PCD_ReadRegister(mfrc, VersionReg);
	printf("Firmware Version: 0x");
	// print the hexa value of a unsigned char
	sprintf(string, "%02X", (char)v);
	printf(string);
	// Lookup which version
	switch (v) {
	case 0x88:
		printf(" = (clone)\r\n");
		break;
	case 0x90:
		printf(" = v0.0\r\n");
		break;
	case 0x91:
		printf(" = v1.0\r\n");
		break;
	case 0x92:
		printf(" = v2.0\r\n");
		break;
	default:
		printf(" = (unknown)\r\n");
	}
	// When 0x00 or 0xFF is returned, communication probably failed
	if ((v == 0x00) || (v == 0xFF))
		printf("WARNING: Communication failure, is the MFRC522 properly "
				 "connected?\r\n");
} // End PCD_DumpVersionToSerial()

/**
 * Dumps debug info about the selected PICC to Serial.
 * On success the PICC is halted after dumping the data.
 * For MIFARE Classic the factory default key of 0xFFFFFFFFFFFF is tried.
 */
void PICC_DumpToSerial(MFRC522Ptr_t mfrc, Uid *uid ///< Pointer to Uid struct
												   ///returned from a successful
												   ///PICC_Select().
					   ) {
	MIFARE_Key key;

	// Dump UID, SAK and Type
	PICC_DumpDetailsToSerial(uid);

	// Dump contents
	PICC_Type piccType = PICC_GetType(uid->sak);
	switch (piccType) {
	case PICC_TYPE_MIFARE_MINI:
	case PICC_TYPE_MIFARE_1K:
	case PICC_TYPE_MIFARE_4K:
		// All keys are set to FFFFFFFFFFFFh at chip delivery from the factory.
		for (uint8_t i = 0; i < 6; i++) {
			key.keybyte[i] = 0xFF;
		}
		PICC_DumpMifareClassicToSerial(mfrc, uid, piccType, &key);
		break;

	case PICC_TYPE_MIFARE_UL:
		PICC_DumpMifareUltralightToSerial(mfrc);
		break;

	case PICC_TYPE_ISO_14443_4:
	case PICC_TYPE_ISO_18092:
	case PICC_TYPE_MIFARE_PLUS:
	case PICC_TYPE_TNP3XXX:
		printf(
			"Dumping memory contents not implemented for that PICC type.\r\n");
		break;

	case PICC_TYPE_UNKNOWN:
	case PICC_TYPE_NOT_COMPLETE:
	default:
		break; // No memory dump here
	}

	printf("\r\n");
	PICC_HaltA(mfrc); // Already done if it was a MIFARE Classic PICC.
} // End PICC_DumpToSerial()

/**
 * Dumps card info (UID,SAK,Type) about the selected PICC to Serial.
 */
void PICC_DumpDetailsToSerial(Uid *uid ///< Pointer to Uid struct returned from
									   ///a successful PICC_Select().
							  ) {
	char string[2];
	// UID
	printf("Card UID:");
	for (uint8_t i = 0; i < uid->size; i++) {
		if (uid->uidByte[i] < 0x10)
			printf(" 0");
		else
			printf(" ");

		// print the hexa value of a unsigned char
		sprintf(string, "%02X", (char)uid->uidByte[i]);
		printf(string);
	}
	printf("\r\n");

	// SAK
	printf("Card SAK: ");
	if (uid->sak < 0x10)
		printf("0");

	// print the hexa value of a unsigned char
	sprintf(string, "%02X", (char)uid->sak);
	printf(string);

	// (suggested) PICC type
	PICC_Type piccType = PICC_GetType(uid->sak);
	printf(" PICC type: ");
	printf(PICC_GetTypeName(piccType));
} // End PICC_DumpDetailsToSerial()

/**
 * Dumps memory contents of a MIFARE Classic PICC.
 * On success the PICC is halted after dumping the data.
 */
void PICC_DumpMifareClassicToSerial(
	MFRC522Ptr_t mfrc,
	Uid *uid,			///< Pointer to Uid struct returned from a successful
						///PICC_Select().
	PICC_Type piccType, ///< One of the PICC_Type enums.
	MIFARE_Key *key		///< Key A used for all sectors.
	) {
	uint8_t no_of_sectors = 0;
	switch (piccType) {
	case PICC_TYPE_MIFARE_MINI:
		// Has 5 sectors * 4 blocks/sector * 16 uint8_ts/block = 320 uint8_ts.
		no_of_sectors = 5;
		break;

	case PICC_TYPE_MIFARE_1K:
		// Has 16 sectors * 4 blocks/sector * 16 uint8_ts/block = 1024 uint8_ts.
		no_of_sectors = 16;
		break;

	case PICC_TYPE_MIFARE_4K:
		// Has (32 sectors * 4 blocks/sector + 8 sectors * 16 blocks/sector) *
		// 16 uint8_ts/block = 4096 uint8_ts.
		no_of_sectors = 40;
		break;

	default: // Should not happen. Ignore.
		break;
	}

	// Dump sectors, highest address first.
	if (no_of_sectors) {
		printf("Sector Block   0  1  2  3   4  5  6  7   8  9 10 11  12 13 "
				 "14 15  AccessBits\r\n");
		for (int8_t i = no_of_sectors - 1; i >= 0; i--) {
			PICC_DumpMifareClassicSectorToSerial(mfrc, uid, key, i);
		}
	}
	PICC_HaltA(mfrc); // Halt the PICC before stopping the encrypted session.
	PCD_StopCrypto1(mfrc);
} // End PICC_DumpMifareClassicToSerial()

/**
 * Dumps memory contents of a sector of a MIFARE Classic PICC.
 * Uses PCD_Authenticate(), MIFARE_Read() and PCD_StopCrypto1.
 * Always uses PICC_CMD_MF_AUTH_KEY_A because only Key A can always read the
 * sector trailer access bits.
 */
void PICC_DumpMifareClassicSectorToSerial(
	MFRC522Ptr_t mfrc,
	Uid *uid,		 ///< Pointer to Uid struct returned from a successful
					 ///PICC_Select().
	MIFARE_Key *key, ///< Key A for the sector.
	uint8_t sector   ///< The sector to dump, 0..39.
	) {
	char string[2];
	uint8_t acces_bit;
	StatusCode status;
	uint8_t firstBlock; // Address of lowest address to dump actually last block
						// dumped)
	uint8_t no_of_blocks; // Number of blocks in sector
	bool isSectorTrailer; // Set to true while handling the "last" (ie highest
						  // address) in the sector.

	// The access bits are stored in a peculiar fashion.
	// There are four groups:
	//		g[3]	Access bits for the sector trailer, block 3 (for sectors 0-31)
	//or block 15 (for sectors 32-39)
	//		g[2]	Access bits for block 2 (for sectors 0-31) or blocks 10-14 (for
	//sectors 32-39)
	//		g[1]	Access bits for block 1 (for sectors 0-31) or blocks 5-9 (for
	//sectors 32-39)
	//		g[0]	Access bits for block 0 (for sectors 0-31) or blocks 0-4 (for
	//sectors 32-39)
	// Each group has access bits [C1 C2 C3]. In this code C1 is MSB and C3 is
	// LSB.
	// The four CX bits are stored together in a nible cx and an inverted nible
	// cx_.
	uint8_t c1, c2, c3;	// Nibbles
	uint8_t c1_, c2_, c3_; // Inverted nibbles
	bool invertedError;	// True if one of the inverted nibbles did not match
	uint8_t g[4];		   // Access bits for each of the four groups.
	uint8_t group;		   // 0-3 - active group for access bits
	bool firstInGroup;	 // True for the first block dumped in the group

	// Determine position and size of sector.
	if (sector < 32) { // Sectors 0..31 has 4 blocks each
		no_of_blocks = 4;
		firstBlock = sector * no_of_blocks;
	} else if (sector < 40) { // Sectors 32-39 has 16 blocks each
		no_of_blocks = 16;
		firstBlock = 128 + (sector - 32) * no_of_blocks;
	} else { // Illegal input, no MIFARE Classic PICC has more than 40 sectors.
		return;
	}

	// Dump blocks, highest address first.
	uint8_t uint8_tCount;
	uint8_t buffer[18];
	uint8_t blockAddr;
	isSectorTrailer = true;
	for (int8_t blockOffset = no_of_blocks - 1; blockOffset >= 0;
		 blockOffset--) {
		blockAddr = firstBlock + blockOffset;
		// Sector number - only on first line
		if (isSectorTrailer) {
			if (sector < 10)
				printf("   "); // Pad with spaces
			else
				printf("  "); // Pad with spaces
			sprintf(string, "%u", sector);
			printf(string);
			printf("   ");
		} else {
			printf("       ");
		}
		// Block number
		if (blockAddr < 10)
			printf("   "); // Pad with spaces
		else {
			if (blockAddr < 100)
				printf("  "); // Pad with spaces
			else
				printf(" "); // Pad with spaces
		}
		sprintf(string, "%u", blockAddr);
		printf(string);
		printf("  ");
		// Establish encrypted communications before reading the first block
		if (isSectorTrailer) {
			status = PCD_Authenticate(mfrc, PICC_CMD_MF_AUTH_KEY_A, firstBlock,
									  key, uid);
			if (status != STATUS_OK) {
				printf("PCD_Authenticate() failed: ");
				printf(GetStatusCodeName(status));
				printf("\n");
				return;
			}
		}
		// Read block
		uint8_tCount = sizeof(buffer);
		status = MIFARE_Read(mfrc, blockAddr, buffer, &uint8_tCount);
		if (status != STATUS_OK) {
			printf("MIFARE_Read() failed: ");
			printf(GetStatusCodeName(status));
			continue;
		}
		// Dump data
		for (uint8_t index = 0; index < 16; index++) {
			if (buffer[index] < 0x10)
				printf(" 0");
			else
				printf(" ");

			// print the hexa value of a unsigned char
			sprintf(string, "%02X", (char)buffer[index]);
			printf(string);
			if ((index % 4) == 3) {
				printf(" ");
			}
		}
		// Parse sector trailer data
		if (isSectorTrailer) {
			c1 = buffer[7] >> 4;
			c2 = buffer[8] & 0xF;
			c3 = buffer[8] >> 4;
			c1_ = buffer[6] & 0xF;
			c2_ = buffer[6] >> 4;
			c3_ = buffer[7] & 0xF;
			invertedError = (c1 != (~c1_ & 0xF)) || (c2 != (~c2_ & 0xF)) ||
							(c3 != (~c3_ & 0xF));
			g[0] = ((c1 & 1) << 2) | ((c2 & 1) << 1) | ((c3 & 1) << 0);
			g[1] = ((c1 & 2) << 1) | ((c2 & 2) << 0) | ((c3 & 2) >> 1);
			g[2] = ((c1 & 4) << 0) | ((c2 & 4) >> 1) | ((c3 & 4) >> 2);
			g[3] = ((c1 & 8) >> 1) | ((c2 & 8) >> 2) | ((c3 & 8) >> 3);
			isSectorTrailer = false;
		}

		// Which access group is this block in?
		if (no_of_blocks == 4) {
			group = blockOffset;
			firstInGroup = true;
		} else {
			group = blockOffset / 5;
			firstInGroup = (group == 3) || (group != (blockOffset + 1) / 5);
		}

		if (firstInGroup) {
			// Print access bits
			printf(" [ ");

			acces_bit = (g[group] >> 2) & 1;
			sprintf(string, "%u", acces_bit);
			printf(string);
			printf(" ");

			acces_bit = (g[group] >> 1) & 1;
			sprintf(string, "%u", acces_bit);
			printf(string);
			printf(" ");

			acces_bit = (g[group] >> 0) & 1;
			sprintf(string, "%u", acces_bit);
			printf(string);

			printf(" ] ");
			if (invertedError) {
				printf(" Inverted access bits did not match! ");
			}
		}

		if (group != 3 &&
			(g[group] == 1 ||
			 g[group] == 6)) { // Not a sector trailer, a value block
			long value = ((long)(buffer[3]) << 24) | ((long)(buffer[2]) << 16) |
						 ((long)(buffer[1]) << 8) | (long)(buffer[0]);
			printf(" Value=0x");

			// print the hexa value of a unsigned char
			sprintf(string, "%02X", (char)value);
			printf(string);
			printf(" Adr=0x");

			// print the hexa value of a unsigned char
			sprintf(string, "%02X", (char)buffer[12]);
			printf(string);
		}
		printf("\r\n");
	}

	return;
} // End PICC_DumpMifareClassicSectorToSerial()

/**
 * Dumps memory contents of a MIFARE Ultralight PICC.
 */
void PICC_DumpMifareUltralightToSerial(MFRC522Ptr_t mfrc) {
	char string[2];
	StatusCode status;
	uint8_t uint8_tCount;
	uint8_t buffer[18];
	uint8_t i;

	printf("Page  0  1  2  3\r\n");
	// Try the mpages of the original Ultralight. Ultralight C has more pages.
	for (uint8_t page = 0; page < 16;
		 page += 4) { // Read returns data for 4 pages at a time.
		// Read pages
		uint8_tCount = sizeof(buffer);
		status = MIFARE_Read(mfrc, page, buffer, &uint8_tCount);
		if (status != STATUS_OK) {
			printf("MIFARE_Read() failed: ");
			printf(GetStatusCodeName(status));
			break;
		}
		// Dump data
		for (uint8_t offset = 0; offset < 4; offset++) {
			i = page + offset;
			if (i < 10)
				printf("  "); // Pad with spaces
			else
				printf(" "); // Pad with spaces
			sprintf(string, "%u", i);
			printf(string);
			printf("  ");
			for (uint8_t index = 0; index < 4; index++) {
				i = 4 * offset + index;
				if (buffer[i] < 0x10)
					printf(" 0");
				else
					printf(" ");

				// print the hexa value of a unsigned char
				sprintf(string, "%02X", (char)buffer[i]);
				printf(string);
			}
			printf("\r\n");
		}
	}
} // End PICC_DumpMifareUltralightToSerial()

/**
 * Calculates the bit pattern needed for the specified access bits. In the [C1
 * C2 C3] tuples C1 is MSB (=4) and C3 is LSB (=1).
 */
void MIFARE_SetAccessBits(
	uint8_t *accessBitBuffer, ///< Pointer to uint8_t 6, 7 and 8 in the sector
							  ///trailer. uint8_ts [0..2] will be set.
	uint8_t g0, ///< Access bits [C1 C2 C3] for block 0 (for sectors 0-31) or
				///blocks 0-4 (for sectors 32-39)
	uint8_t g1, ///< Access bits C1 C2 C3] for block 1 (for sectors 0-31) or
				///blocks 5-9 (for sectors 32-39)
	uint8_t g2, ///< Access bits C1 C2 C3] for block 2 (for sectors 0-31) or
				///blocks 10-14 (for sectors 32-39)
	uint8_t g3  ///< Access bits C1 C2 C3] for the sector trailer, block 3 (for
				///sectors 0-31) or block 15 (for sectors 32-39)
	) {
	uint8_t c1 =
		((g3 & 4) << 1) | ((g2 & 4) << 0) | ((g1 & 4) >> 1) | ((g0 & 4) >> 2);
	uint8_t c2 =
		((g3 & 2) << 2) | ((g2 & 2) << 1) | ((g1 & 2) << 0) | ((g0 & 2) >> 1);
	uint8_t c3 =
		((g3 & 1) << 3) | ((g2 & 1) << 2) | ((g1 & 1) << 1) | ((g0 & 1) << 0);

	accessBitBuffer[0] = (~c2 & 0xF) << 4 | (~c1 & 0xF);
	accessBitBuffer[1] = c1 << 4 | (~c3 & 0xF);
	accessBitBuffer[2] = c3 << 4 | c2;
} // End MIFARE_SetAccessBits()

/**
 * Performs the "magic sequence" needed to get Chinese UID changeable
 * Mifare cards to allow writing to sector 0, where the card UID is stored.
 *
 * Note that you do not need to have selected the card through REQA or WUPA,
 * this sequence works immediately when the card is in the reader vicinity.
 * This means you can use this method even on "bricked" cards that your reader
 *does
 * not recognise anymore (see MIFARE_UnbrickUidSector).
 *
 * Of course with non-bricked devices, you're free to select them before calling
 *this function.
 */
bool MIFARE_OpenUidBackdoor(MFRC522Ptr_t mfrc, bool logErrors) {
	char string[2];
	// Magic sequence:
	// > 50 00 57 CD (HALT + CRC)
	// > 40 (7 bits only)
	// < A (4 bits only)
	// > 43
	// < A (4 bits only)
	// Then you can write to sector 0 without authenticating

	PICC_HaltA(mfrc); // 50 00 57 CD

	uint8_t cmd = 0x40;
	uint8_t validBits =
		7; /* Our command is only 7 bits. After receiving card response,
		  this will contain amount of valid response bits. */
	uint8_t response[32]; // Card's response is written here
	uint8_t received;
	StatusCode status =
		PCD_TransceiveData(mfrc, &cmd, (uint8_t)1, response, &received,
						   &validBits, (uint8_t)0, false); // 40
	if (status != STATUS_OK) {
		if (logErrors) {
			printf("Card did not respond to 0x40 after HALT command. Are you "
					 "sure it is a UID changeable one?\r\n");
			printf("Error name: ");
			printf(GetStatusCodeName(status));
		}
		return false;
	}
	if (received != 1 || response[0] != 0x0A) {
		if (logErrors) {
			printf("Got bad response on backdoor 0x40 command: ");

			// print the hexa value of a unsigned char
			sprintf(string, "%02X", (char)response[0]);
			printf(string);
			printf(" (");
			sprintf(string, "%u", validBits);
			printf(string);
			printf(" valid bits)\r\n");
		}
		return false;
	}

	cmd = 0x43;
	validBits = 8;
	status = PCD_TransceiveData(mfrc, &cmd, (uint8_t)1, response, &received,
								&validBits, (uint8_t)0, false); // 43
	if (status != STATUS_OK) {
		if (logErrors) {
			printf("Error in communication at command 0x43, after "
					 "successfully executing 0x40\r\n");
			printf("Error name: ");
			printf(GetStatusCodeName(status));
		}
		return false;
	}
	if (received != 1 || response[0] != 0x0A) {
		if (logErrors) {
			printf("Got bad response on backdoor 0x43 command: ");

			// print the hexa value of a unsigned char
			sprintf(string, "%02X", (char)response[0]);
			printf(string);
			printf(" (");
			sprintf(string, "%u", validBits);
			printf(string);
			printf(" valid bits)\r\n");
		}
		return false;
	}

	// You can now write to sector 0 without authenticating!
	return true;
} // End MIFARE_OpenUidBackdoor()

/**
 * Reads entire block 0, including all manufacturer data, and overwrites
 * that block with the new UID, a freshly calculated BCC, and the original
 * manufacturer data.
 *
 * It assumes a default KEY A of 0xFFFFFFFFFFFF.
 * Make sure to have selected the card before this function is called.
 */
bool MIFARE_SetUid(MFRC522Ptr_t mfrc, uint8_t *newUid, uint8_t uidSize,
				   bool logErrors) {

	// UID + BCC uint8_t can not be larger than 16 together
	if (!newUid || !uidSize || uidSize > 15) {
		if (logErrors) {
			printf("New UID buffer empty, size 0, or size > 15 given\r\n");
		}
		return false;
	}

	// Authenticate for reading
	MIFARE_Key key = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
	StatusCode status = PCD_Authenticate(mfrc, PICC_CMD_MF_AUTH_KEY_A,
										 (uint8_t)1, &key, &(mfrc->uid));
	if (status != STATUS_OK) {

		if (status == STATUS_TIMEOUT) {
			// We get a read timeout if no card is selected yet, so let's select
			// one

			// Wake the card up again if sleeping
			//			  uint8_t atqa_answer[2];
			//			  uint8_t atqa_size = 2;
			//			  PICC_WakeupA(atqa_answer, &atqa_size);

			if (!PICC_IsNewCardPresent(mfrc) || !PICC_ReadCardSerial(mfrc)) {
				printf("No card was previously selected, and none are "
						 "available. Failed to set UID.\r\n");
				return false;
			}

			status = PCD_Authenticate(mfrc, PICC_CMD_MF_AUTH_KEY_A, (uint8_t)1,
									  &key, &(mfrc->uid));
			if (status != STATUS_OK) {
				// We tried, time to give up
				if (logErrors) {
					printf("Failed to authenticate to card for reading, "
							 "could not set UID: \r\n");
					printf(GetStatusCodeName(status));
				}
				return false;
			}
		} else {
			if (logErrors) {
				printf("PCD_Authenticate() failed: ");
				printf(GetStatusCodeName(status));
				printf("\n");
			}
			return false;
		}
	}

	// Read block 0
	uint8_t block0_buffer[18];
	uint8_t uint8_tCount = sizeof(block0_buffer);
	status = MIFARE_Read(mfrc, (uint8_t)0, block0_buffer, &uint8_tCount);
	if (status != STATUS_OK) {
		if (logErrors) {
			printf("MIFARE_Read() failed: ");
			printf(GetStatusCodeName(status));
			printf(
				"Are you sure your KEY A for sector 0 is 0xFFFFFFFFFFFF?\r\n");
		}
		return false;
	}

	// Write new UID to the data we just read, and calculate BCC uint8_t
	uint8_t bcc = 0;
	for (int i = 0; i < uidSize; i++) {
		block0_buffer[i] = newUid[i];
		bcc ^= newUid[i];
	}

	// Write BCC uint8_t to buffer
	block0_buffer[uidSize] = bcc;

	// Stop encrypted traffic so we can send raw uint8_ts
	PCD_StopCrypto1(mfrc);

	// Activate UID backdoor
	if (!MIFARE_OpenUidBackdoor(mfrc, logErrors)) {
		if (logErrors) {
			printf("Activating the UID backdoor failed.\r\n");
		}
		return false;
	}

	// Write modified block 0 back to card
	status = MIFARE_Write(mfrc, (uint8_t)0, block0_buffer, (uint8_t)16);
	if (status != STATUS_OK) {
		if (logErrors) {
			printf("MIFARE_Write() failed: ");
			printf(GetStatusCodeName(status));
		}
		return false;
	}

	// Wake the card up again
	uint8_t atqa_answer[2];
	uint8_t atqa_size = 2;
	PICC_WakeupA(mfrc, atqa_answer, &atqa_size);

	return true;
}

/**
 * Resets entire sector 0 to zeroes, so the card can be read again by readers.
 */
bool MIFARE_UnbrickUidSector(MFRC522Ptr_t mfrc, bool logErrors) {
	MIFARE_OpenUidBackdoor(mfrc, logErrors);

	uint8_t block0_buffer[] = {0x01, 0x02, 0x03, 0x04, 0x04, 0x00, 0x00, 0x00,
							   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

	// Write modified block 0 back to card
	StatusCode status =
		MIFARE_Write(mfrc, (uint8_t)0, block0_buffer, (uint8_t)16);
	if (status != STATUS_OK) {
		if (logErrors) {
			printf("MIFARE_Write() failed: ");
			printf(GetStatusCodeName(status));
		}
		return false;
	}
	return true;
}

/*******************************************************************************
* Convenience functions - does not add extra functionality
*******************************************************************************/

/**
 * Returns true if a PICC responds to PICC_CMD_REQA.
 * Only "new" cards in state IDLE are invited. Sleeping cards in state HALT are
 *ignored.
 *
 * @return bool
 */
bool PICC_IsNewCardPresent(MFRC522Ptr_t mfrc) {
	uint8_t bufferATQA[2];
	uint8_t bufferSize = sizeof(bufferATQA);
	StatusCode result = PICC_RequestA(mfrc, bufferATQA, &bufferSize);
	return (result == STATUS_OK || result == STATUS_COLLISION);
} // End PICC_IsNewCardPresent()

/**
 * Simple wrapper around PICC_Select.
 * Returns true if a UID could be read.
 * Remember to call PICC_IsNewCardPresent(), PICC_RequestA() or PICC_WakeupA()
 *first.
 * The read UID is available in the class variable uid.
 *
 * @return bool
 */
bool PICC_ReadCardSerial(MFRC522Ptr_t mfrc) {
	StatusCode result = PICC_Select(mfrc, &(mfrc->uid), 0);
	return (result == STATUS_OK);
} // End

static inline void cs_select(const uint cs) {
    asm volatile("nop \n nop \n nop");
    gpio_put(cs, 0); // Active low
    asm volatile("nop \n nop \n nop");
}

static inline void cs_deselect(const uint cs) {
    asm volatile("nop \n nop \n nop");
    gpio_put(cs, 1);
    asm volatile("nop \n nop \n nop");
}