v1.1

Dependencies:   mbed QEI

Files at this revision

API Documentation at this revision

Comitter:
sippasaeng
Date:
Sun May 05 18:17:07 2019 +0000
Parent:
3:054df6da48b5
Commit message:
v1.1 update char-->int type

Changed in this revision

RF/MFRC522.cpp Show annotated file Show diff for this revision Revisions of this file
RF/MFRC522.h Show annotated file Show diff for this revision Revisions of this file
main.cpp Show annotated file Show diff for this revision Revisions of this file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/RF/MFRC522.cpp	Sun May 05 18:17:07 2019 +0000
@@ -0,0 +1,1154 @@
+/*
+* MFRC522.cpp - Library to use ARDUINO RFID MODULE KIT 13.56 MHZ WITH TAGS SPI W AND R BY COOQROBOT.
+* _Please_ see the comments in MFRC522.h - they give useful hints and background.
+* Released into the public domain.
+*/
+
+#include "MFRC522.h"
+
+static const char* const _TypeNamePICC[] =
+{
+  "Unknown type",
+  "PICC compliant with ISO/IEC 14443-4",
+  "PICC compliant with ISO/IEC 18092 (NFC)",
+  "MIFARE Mini, 320 bytes",
+  "MIFARE 1KB",
+  "MIFARE 4KB",
+  "MIFARE Ultralight or Ultralight C",
+  "MIFARE Plus",
+  "MIFARE TNP3XXX",
+
+  /* not complete UID */
+  "SAK indicates UID is not complete"
+};
+
+static const char* const _ErrorMessage[] =
+{
+  "Unknown error",
+  "Success",
+  "Error in communication",
+  "Collision detected",
+  "Timeout in communication",
+  "A buffer is not big enough",
+  "Internal error in the code, should not happen",
+  "Invalid argument",
+  "The CRC_A does not match",
+  "A MIFARE PICC responded with NAK"
+};
+
+#define MFRC522_MaxPICCs (sizeof(_TypeNamePICC)/sizeof(_TypeNamePICC[0]))
+#define MFRC522_MaxError (sizeof(_ErrorMessage)/sizeof(_ErrorMessage[0]))
+
+/////////////////////////////////////////////////////////////////////////////////////
+// Functions for setting up the driver
+/////////////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Constructor.
+ * Prepares the output pins.
+ */
+MFRC522::MFRC522(PinName mosi,
+                 PinName miso,
+                 PinName sclk,
+                 PinName cs,
+                 PinName reset) : m_SPI(mosi, miso, sclk), m_CS(cs), m_RESET(reset)
+{
+  /* Configure SPI bus */
+  m_SPI.format(8, 0);
+  m_SPI.frequency(8000000);
+
+  /* Release SPI-CS pin */
+  m_CS       = 1;
+
+  /* Release RESET pin */
+  m_RESET    = 1;
+} // End constructor
+
+
+/**
+ * Destructor.
+ */
+MFRC522::~MFRC522()
+{
+
+}
+
+
+/////////////////////////////////////////////////////////////////////////////////////
+// Basic interface functions for communicating with the MFRC522
+/////////////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Writes a byte to the specified register in the MFRC522 chip.
+ * The interface is described in the datasheet section 8.1.2.
+ */
+void MFRC522::PCD_WriteRegister(uint8_t reg, uint8_t value)
+{
+  m_CS = 0; /* Select SPI Chip MFRC522 */
+
+  // MSB == 0 is for writing. LSB is not used in address. Datasheet section 8.1.2.3.
+  (void) m_SPI.write(reg & 0x7E);
+  (void) m_SPI.write(value);
+
+  m_CS = 1; /* Release SPI Chip MFRC522 */
+} // End PCD_WriteRegister()
+
+/**
+ * Writes a number of bytes to the specified register in the MFRC522 chip.
+ * The interface is described in the datasheet section 8.1.2.
+ */
+void MFRC522::PCD_WriteRegister(uint8_t reg, uint8_t count, uint8_t *values)
+{
+  m_CS = 0; /* Select SPI Chip MFRC522 */
+
+  // MSB == 0 is for writing. LSB is not used in address. Datasheet section 8.1.2.3.
+  (void) m_SPI.write(reg & 0x7E);
+  for (uint8_t index = 0; index < count; index++)
+  {
+    (void) m_SPI.write(values[index]);
+  }
+
+  m_CS = 1; /* Release SPI Chip MFRC522 */
+} // End PCD_WriteRegister()
+
+/**
+ * Reads a byte from the specified register in the MFRC522 chip.
+ * The interface is described in the datasheet section 8.1.2.
+ */
+uint8_t MFRC522::PCD_ReadRegister(uint8_t reg)
+{
+  uint8_t value;
+  m_CS = 0; /* Select SPI Chip MFRC522 */
+
+  // MSB == 1 is for reading. LSB is not used in address. Datasheet section 8.1.2.3.
+  (void) m_SPI.write(0x80 | reg);
+
+  // Read the value back. Send 0 to stop reading.
+  value = m_SPI.write(0);
+
+  m_CS = 1; /* Release SPI Chip MFRC522 */
+
+  return value;
+} // End PCD_ReadRegister()
+
+/**
+ * Reads a number of bytes from the specified register in the MFRC522 chip.
+ * The interface is described in the datasheet section 8.1.2.
+ */
+void MFRC522::PCD_ReadRegister(uint8_t reg, uint8_t count, uint8_t *values, uint8_t rxAlign)
+{
+  if (count == 0) { return; }
+
+  uint8_t address = 0x80 | reg;  // MSB == 1 is for reading. LSB is not used in address. Datasheet section 8.1.2.3.
+  uint8_t index = 0;             // Index in values array.
+
+  m_CS = 0;                      /* Select SPI Chip MFRC522 */
+  count--;                       // One read is performed outside of the loop
+  (void) m_SPI.write(address);   // Tell MFRC522 which address we want to read
+
+  while (index < count)
+  {
+    if ((index == 0) && rxAlign) // Only update bit positions rxAlign..7 in values[0]
+    {
+      // Create bit mask for bit positions rxAlign..7
+      uint8_t mask = 0;
+      for (uint8_t i = rxAlign; i <= 7; i++)
+      {
+        mask |= (1 << i);
+      }
+
+      // Read value and tell that we want to read the same address again.
+      uint8_t value = m_SPI.write(address);
+
+      // Apply mask to both current value of values[0] and the new data in value.
+      values[0] = (values[index] & ~mask) | (value & mask);
+    }
+    else
+    {
+      // Read value and tell that we want to read the same address again.
+      values[index] = m_SPI.write(address);
+    }
+
+    index++;
+  }
+
+  values[index] = m_SPI.write(0); // Read the final byte. Send 0 to stop reading.
+
+  m_CS = 1;                       /* Release SPI Chip MFRC522 */
+} // End PCD_ReadRegister()
+
+/**
+ * Sets the bits given in mask in register reg.
+ */
+void MFRC522::PCD_SetRegisterBits(uint8_t reg, uint8_t mask)
+{
+  uint8_t tmp = PCD_ReadRegister(reg);
+  PCD_WriteRegister(reg, tmp | mask);     // set bit mask
+} // End PCD_SetRegisterBitMask()
+
+/**
+ * Clears the bits given in mask from register reg.
+ */
+void MFRC522::PCD_ClrRegisterBits(uint8_t reg, uint8_t mask)
+{
+  uint8_t tmp = PCD_ReadRegister(reg);
+  PCD_WriteRegister(reg, tmp & (~mask));    // clear bit mask
+} // End PCD_ClearRegisterBitMask()
+
+
+/**
+ * Use the CRC coprocessor in the MFRC522 to calculate a CRC_A.
+ */
+uint8_t MFRC522::PCD_CalculateCRC(uint8_t *data, uint8_t length, uint8_t *result)
+{
+  PCD_WriteRegister(CommandReg, PCD_Idle);      // Stop any active command.
+  PCD_WriteRegister(DivIrqReg, 0x04);           // Clear the CRCIRq interrupt request bit
+  PCD_SetRegisterBits(FIFOLevelReg, 0x80);      // FlushBuffer = 1, FIFO initialization
+  PCD_WriteRegister(FIFODataReg, length, data); // Write data to the FIFO
+  PCD_WriteRegister(CommandReg, PCD_CalcCRC);   // Start the calculation
+
+  // Wait for the CRC calculation to complete. Each iteration of the while-loop takes 17.73us.
+  uint16_t i = 5000;
+  uint8_t n;
+  while (1)
+  {
+    n = PCD_ReadRegister(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;
+    }
+  }
+
+  // Stop calculating CRC for new content in the FIFO.
+  PCD_WriteRegister(CommandReg, PCD_Idle);
+
+  // Transfer the result from the registers to the result buffer
+  result[0] = PCD_ReadRegister(CRCResultRegL);
+  result[1] = PCD_ReadRegister(CRCResultRegH);
+  return STATUS_OK;
+} // End PCD_CalculateCRC()
+
+
+/////////////////////////////////////////////////////////////////////////////////////
+// Functions for manipulating the MFRC522
+/////////////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Initializes the MFRC522 chip.
+ */
+void MFRC522::PCD_Init()
+{
+  /* Reset MFRC522 */
+  m_RESET = 0;
+  wait_ms(10);
+  m_RESET = 1;
+  
+  // Section 8.8.2 in the datasheet says the oscillator start-up time is the start up time of the crystal + 37,74us. Let us be generous: 50ms.
+  wait_ms(50);
+
+  // 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(TModeReg, 0x80);      // TAuto=1; timer starts automatically at the end of the transmission in all communication modes at all speeds
+  PCD_WriteRegister(TPrescalerReg, 0xA9); // TPreScaler = TModeReg[3..0]:TPrescalerReg, ie 0x0A9 = 169 => f_timer=40kHz, ie a timer period of 25us.
+  PCD_WriteRegister(TReloadRegH, 0x03);   // Reload timer with 0x3E8 = 1000, ie 25ms before timeout.
+  PCD_WriteRegister(TReloadRegL, 0xE8);
+
+  PCD_WriteRegister(TxASKReg, 0x40);      // Default 0x00. Force a 100 % ASK modulation independent of the ModGsPReg register setting
+  PCD_WriteRegister(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_WriteRegister(RFCfgReg, (0x07<<4)); // Set Rx Gain to max
+
+  PCD_AntennaOn();                        // 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 MFRC522::PCD_Reset()
+{
+  PCD_WriteRegister(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 + 37,74us. Let us be generous: 50ms.
+  wait_ms(50);
+
+  // Wait for the PowerDown bit in CommandReg to be cleared
+  while (PCD_ReadRegister(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 disabled.
+ */
+void MFRC522::PCD_AntennaOn()
+{
+  uint8_t value = PCD_ReadRegister(TxControlReg);
+  if ((value & 0x03) != 0x03)
+  {
+    PCD_WriteRegister(TxControlReg, value | 0x03);
+  }
+} // End PCD_AntennaOn()
+
+/////////////////////////////////////////////////////////////////////////////////////
+// Functions for communicating with PICCs
+/////////////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Executes the Transceive command.
+ * CRC validation can only be done if backData and backLen are specified.
+ */
+uint8_t MFRC522::PCD_TransceiveData(uint8_t *sendData,
+                                    uint8_t sendLen,
+                                    uint8_t *backData,
+                                    uint8_t *backLen,
+                                    uint8_t *validBits,
+                                    uint8_t rxAlign,
+                                    bool    checkCRC)
+{
+  uint8_t waitIRq = 0x30;    // RxIRq and IdleIRq
+  return PCD_CommunicateWithPICC(PCD_Transceive, waitIRq, sendData, sendLen, backData, backLen, validBits, rxAlign, checkCRC);
+} // End PCD_TransceiveData()
+
+/**
+ * Transfers data to the MFRC522 FIFO, executes a commend, waits for completion and transfers data back from the FIFO.
+ * CRC validation can only be done if backData and backLen are specified.
+ */
+uint8_t MFRC522::PCD_CommunicateWithPICC(uint8_t command,
+                                         uint8_t waitIRq,
+                                         uint8_t *sendData,
+                                         uint8_t sendLen,
+                                         uint8_t *backData,
+                                         uint8_t *backLen,
+                                         uint8_t *validBits,
+                                         uint8_t rxAlign,
+                                         bool    checkCRC)
+{
+  uint8_t n, _validBits = 0;
+  uint32_t 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(CommandReg, PCD_Idle);            // Stop any active command.
+  PCD_WriteRegister(ComIrqReg, 0x7F);                 // Clear all seven interrupt request bits
+  PCD_SetRegisterBits(FIFOLevelReg, 0x80);            // FlushBuffer = 1, FIFO initialization
+  PCD_WriteRegister(FIFODataReg, sendLen, sendData);  // Write sendData to the FIFO
+  PCD_WriteRegister(BitFramingReg, bitFraming);       // Bit adjustments
+  PCD_WriteRegister(CommandReg, command);             // Execute the command
+  if (command == PCD_Transceive)
+  {
+    PCD_SetRegisterBits(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 17.86us.
+  i = 2000;
+  while (1)
+  {
+    n = PCD_ReadRegister(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 condions 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(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(FIFOLevelReg);           // Number of bytes in the FIFO
+    if (n > *backLen)
+    {
+      return STATUS_NO_ROOM;
+    }
+
+    *backLen = n;                       // Number of bytes returned
+    PCD_ReadRegister(FIFODataReg, n, backData, rxAlign);    // Get received data from FIFO
+    _validBits = PCD_ReadRegister(ControlReg) & 0x07; // RxLastBits[2:0] indicates the number of valid bits in the last received byte. If this value is 000b, the whole byte 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 byte 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];
+    n = PCD_CalculateCRC(&backData[0], *backLen - 2, &controlBuffer[0]);
+    if (n != STATUS_OK)
+    {
+      return n;
+    }
+
+    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.
+ */
+uint8_t MFRC522::PICC_RequestA(uint8_t *bufferATQA, uint8_t *bufferSize)
+{
+  return PICC_REQA_or_WUPA(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.
+ */
+uint8_t MFRC522::PICC_WakeupA(uint8_t *bufferATQA, uint8_t *bufferSize)
+{
+  return PICC_REQA_or_WUPA(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.
+ */
+uint8_t MFRC522::PICC_REQA_or_WUPA(uint8_t command, uint8_t *bufferATQA, uint8_t *bufferSize)
+{
+  uint8_t validBits;
+  uint8_t status;
+
+  if (bufferATQA == NULL || *bufferSize < 2)
+  {  // The ATQA response is 2 bytes long.
+    return STATUS_NO_ROOM;
+  }
+
+  // ValuesAfterColl=1 => Bits received after collision are cleared.
+  PCD_ClrRegisterBits(CollReg, 0x80);
+
+  // For REQA and WUPA we need the short frame format
+  // - transmit only 7 bits of the last (and only) byte. TxLastBits = BitFramingReg[2..0]
+  validBits = 7;
+
+  status = PCD_TransceiveData(&command, 1, bufferATQA, bufferSize, &validBits);
+  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.
+ */
+uint8_t MFRC522::PICC_Select(Uid *uid, uint8_t validBits)
+{
+  bool uidComplete;
+  bool selectDone;
+  bool useCascadeTag;
+  uint8_t cascadeLevel = 1;
+  uint8_t result;
+  uint8_t count;
+  uint8_t index;
+  uint8_t uidIndex;          // The first index in uid->uidByte[] that is used in the current Cascade Level.
+  uint8_t currentLevelKnownBits;   // The number of known UID bits in the current Cascade Level.
+  uint8_t buffer[9];         // The SELECT/ANTICOLLISION commands uses a 7 byte standard frame + 2 bytes CRC_A
+  uint8_t bufferUsed;        // The number of bytes used in the buffer, ie the number of bytes 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 byte.
+  uint8_t *responseBuffer;
+  uint8_t responseLength;
+
+  // Description of buffer structure:
+  //    Byte 0: SEL         Indicates the Cascade Level: PICC_CMD_SEL_CL1, PICC_CMD_SEL_CL2 or PICC_CMD_SEL_CL3
+  //    Byte 1: NVB         Number of Valid Bits (in complete command, not just the UID): High nibble: complete bytes, Low nibble: Extra bits.
+  //    Byte 2: UID-data or CT    See explanation below. CT means Cascade Tag.
+  //    Byte 3: UID-data
+  //    Byte 4: UID-data
+  //    Byte 5: UID-data
+  //    Byte 6: BCC         Block Check Character - XOR of bytes 2-5
+  //    Byte 7: CRC_A
+  //    Byte 8: CRC_A
+  // The BCC and CRC_A is only transmitted if we know all the UID bits of the current Cascade Level.
+  //
+  // Description of bytes 2-5: (Section 6.5.4 of the ISO/IEC 14443-3 draft: UID contents and cascade levels)
+  //    UID size  Cascade level Byte2 Byte3 Byte4 Byte5
+  //    ========  ============= ===== ===== ===== =====
+  //     4 bytes    1     uid0  uid1  uid2  uid3
+  //     7 bytes    1     CT    uid0  uid1  uid2
+  //                2     uid3  uid4  uid5  uid6
+  //    10 bytes    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
+  // ValuesAfterColl=1 => Bits received after collision are cleared.
+  PCD_ClrRegisterBits(CollReg, 0x80);
+
+  // Repeat Cascade Level loop until we have a complete UID.
+  uidComplete = false;
+  while ( ! uidComplete)
+  {
+    // Set the Cascade Level in the SEL byte, find out if we need to use the Cascade Tag in byte 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 bytes
+        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 bytes
+        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?
+    if(validBits > (8 * uidIndex))
+    {
+      currentLevelKnownBits = validBits - (8 * uidIndex);
+    }
+    else
+    {
+      currentLevelKnownBits = 0;
+    }
+
+    // Copy the known bits from uid->uidByte[] to buffer[]
+    index = 2; // destination index in buffer[]
+    if (useCascadeTag)
+    {
+      buffer[index++] = PICC_CMD_CT;
+    }
+
+    uint8_t bytesToCopy = currentLevelKnownBits / 8 + (currentLevelKnownBits % 8 ? 1 : 0); // The number of bytes needed to represent the known bits for this level.
+    if (bytesToCopy)
+    {
+      // Max 4 bytes in each Cascade Level. Only 3 left if we use the Cascade Tag
+      uint8_t maxBytes = useCascadeTag ? 3 : 4;
+      if (bytesToCopy > maxBytes)
+      {
+        bytesToCopy = maxBytes;
+      }
+
+      for (count = 0; count < bytesToCopy; 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 bytes to send and receive.
+      if (currentLevelKnownBits >= 32)
+      { // All UID bits in this Cascade Level are known. This is a SELECT.
+        //Serial.print("SELECT: currentLevelKnownBits="); Serial.println(currentLevelKnownBits, DEC);
+        buffer[1] = 0x70; // NVB - Number of Valid Bits: Seven whole bytes
+
+        // Calulate BCC - Block Check Character
+        buffer[6] = buffer[2] ^ buffer[3] ^ buffer[4] ^ buffer[5];
+
+        // Calculate CRC_A
+        result = PCD_CalculateCRC(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 bytes of buffer (BCC and CRC_A - not needed after tx)
+        responseBuffer  = &buffer[6];
+        responseLength  = 3;
+      }
+      else
+      { // This is an ANTICOLLISION.
+        //Serial.print("ANTICOLLISION: currentLevelKnownBits="); Serial.println(currentLevelKnownBits, DEC);
+        txLastBits     = currentLevelKnownBits % 8;
+        count          = currentLevelKnownBits / 8;  // Number of whole bytes in the UID part.
+        index          = 2 + count;                  // Number of whole bytes: 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 seperate variable is overkill. But it makes the next line easier to read.
+      PCD_WriteRegister(BitFramingReg, (rxAlign << 4) + txLastBits);  // RxAlign = BitFramingReg[6..4]. TxLastBits = BitFramingReg[2..0]
+
+      // Transmit the buffer and receive the response.
+      result = PCD_TransceiveData(buffer, bufferUsed, responseBuffer, &responseLength, &txLastBits, rxAlign);
+      if (result == STATUS_COLLISION)
+      { // More than one PICC in the field => collision.
+        result = PCD_ReadRegister(CollReg);     // CollReg[7..0] bits are: ValuesAfterColl reserved CollPosNotValid CollPos[4:0]
+        if (result & 0x20)
+        { // CollPosNotValid
+          return STATUS_COLLISION; // Without a valid collision position we cannot continue
+        }
+
+        uint8_t collisionPos = result & 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 byte 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 bytes from buffer[] to uid->uidByte[]
+    index       = (buffer[2] == PICC_CMD_CT) ? 3 : 2; // source index in buffer[]
+    bytesToCopy = (buffer[2] == PICC_CMD_CT) ? 3 : 4;
+    for (count = 0; count < bytesToCopy; count++)
+    {
+      uid->uidByte[uidIndex + count] = buffer[index++];
+    }
+
+    // Check response SAK (Select Acknowledge)
+    if (responseLength != 3 || txLastBits != 0)
+    {   // SAK must be exactly 24 bits (1 byte + CRC_A).
+      return STATUS_ERROR;
+    }
+
+    // Verify CRC_A - do our own calculation and store the control in buffer[2..3] - those bytes are not needed anymore.
+    result = PCD_CalculateCRC(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.
+ */
+uint8_t MFRC522::PICC_HaltA()
+{
+  uint8_t result;
+  uint8_t buffer[4];
+
+  // Build command buffer
+  buffer[0] = PICC_CMD_HLTA;
+  buffer[1] = 0;
+
+  // Calculate CRC_A
+  result = PCD_CalculateCRC(buffer, 2, &buffer[2]);
+  if (result == STATUS_OK)
+  {
+    // 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 an success.
+    result = PCD_TransceiveData(buffer, sizeof(buffer), NULL, 0);
+    if (result == STATUS_TIMEOUT)
+    {
+      result = STATUS_OK;
+    }
+    else if (result == STATUS_OK)
+    { // That is ironically NOT ok in this case ;-)
+      result = STATUS_ERROR;
+    }
+  }
+
+  return result;
+} // End PICC_HaltA()
+
+
+/////////////////////////////////////////////////////////////////////////////////////
+// Functions for communicating with MIFARE PICCs
+/////////////////////////////////////////////////////////////////////////////////////
+
+/*
+ * Executes the MFRC522 MFAuthent command.
+ */
+uint8_t MFRC522::PCD_Authenticate(uint8_t command, uint8_t blockAddr, MIFARE_Key *key, Uid *uid)
+{
+  uint8_t i, waitIRq = 0x10;    // IdleIRq
+
+  // Build command buffer
+  uint8_t sendData[12];
+  sendData[0] = command;
+  sendData[1] = blockAddr;
+
+  for (i = 0; i < MF_KEY_SIZE; i++)
+  {  // 6 key bytes
+    sendData[2+i] = key->keyByte[i];
+  }
+
+  for (i = 0; i < 4; i++)
+  { // The first 4 bytes of the UID
+    sendData[8+i] = uid->uidByte[i];
+  }
+
+  // Start the authentication.
+  return PCD_CommunicateWithPICC(PCD_MFAuthent, waitIRq, &sendData[0], sizeof(sendData));
+} // 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 MFRC522::PCD_StopCrypto1()
+{
+  // Clear MFCrypto1On bit
+  PCD_ClrRegisterBits(Status2Reg, 0x08); // Status2Reg[7..0] bits are: TempSensClear I2CForceHS reserved reserved   MFCrypto1On ModemState[2:0]
+} // End PCD_StopCrypto1()
+
+/*
+ * Reads 16 bytes (+ 2 bytes CRC_A) from the active PICC.
+ */
+uint8_t MFRC522::MIFARE_Read(uint8_t blockAddr, uint8_t *buffer, uint8_t *bufferSize)
+{
+  uint8_t result = STATUS_NO_ROOM;
+
+  // Sanity check
+  if ((buffer == NULL) || (*bufferSize < 18))
+  {
+    return result;
+  }
+
+  // Build command buffer
+  buffer[0] = PICC_CMD_MF_READ;
+  buffer[1] = blockAddr;
+
+  // Calculate CRC_A
+  result = PCD_CalculateCRC(buffer, 2, &buffer[2]);
+  if (result != STATUS_OK)
+  {
+    return result;
+  }
+
+  // Transmit the buffer and receive the response, validate CRC_A.
+  return PCD_TransceiveData(buffer, 4, buffer, bufferSize, NULL, 0, true);
+} // End MIFARE_Read()
+
+/*
+ * Writes 16 bytes to the active PICC.
+ */
+uint8_t MFRC522::MIFARE_Write(uint8_t blockAddr, uint8_t *buffer, uint8_t bufferSize)
+{
+  uint8_t 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;
+  // Adds CRC_A and checks that the response is MF_ACK.
+  result = PCD_MIFARE_Transceive(cmdBuffer, 2);
+  if (result != STATUS_OK)
+  {
+    return result;
+  }
+
+  // Step 2: Transfer the data
+  // Adds CRC_A and checks that the response is MF_ACK.
+  result = PCD_MIFARE_Transceive(buffer, bufferSize);
+  if (result != STATUS_OK)
+  {
+    return result;
+  }
+
+  return STATUS_OK;
+} // End MIFARE_Write()
+
+/*
+ * Writes a 4 byte page to the active MIFARE Ultralight PICC.
+ */
+uint8_t MFRC522::MIFARE_UltralightWrite(uint8_t page, uint8_t *buffer, uint8_t bufferSize)
+{
+  uint8_t 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(cmdBuffer, 6); // 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.
+ */
+uint8_t MFRC522::MIFARE_Decrement(uint8_t blockAddr, uint32_t delta)
+{
+  return MIFARE_TwoStepHelper(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.
+ */
+uint8_t MFRC522::MIFARE_Increment(uint8_t blockAddr, uint32_t delta)
+{
+  return MIFARE_TwoStepHelper(PICC_CMD_MF_INCREMENT, blockAddr, delta);
+} // End MIFARE_Increment()
+
+/**
+ * MIFARE Restore copies the value of the addressed block into a volatile memory.
+ */
+uint8_t MFRC522::MIFARE_Restore(uint8_t blockAddr)
+{
+  // 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(PICC_CMD_MF_RESTORE, blockAddr, 0L);
+} // End MIFARE_Restore()
+
+/*
+ * Helper function for the two-step MIFARE Classic protocol operations Decrement, Increment and Restore.
+ */
+uint8_t MFRC522::MIFARE_TwoStepHelper(uint8_t command, uint8_t blockAddr, uint32_t data)
+{
+  uint8_t result;
+  uint8_t cmdBuffer[2]; // We only need room for 2 bytes.
+
+  // Step 1: Tell the PICC the command and block address
+  cmdBuffer[0] = command;
+  cmdBuffer[1] = blockAddr;
+
+  // Adds CRC_A and checks that the response is MF_ACK.
+  result = PCD_MIFARE_Transceive(cmdBuffer, 2);
+  if (result != STATUS_OK)
+  {
+    return result;
+  }
+
+  // Step 2: Transfer the data
+  // Adds CRC_A and accept timeout as success.
+  result = PCD_MIFARE_Transceive((uint8_t *) &data, 4, true);
+  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.
+ */
+uint8_t MFRC522::MIFARE_Transfer(uint8_t blockAddr)
+{
+  uint8_t cmdBuffer[2]; // We only need room for 2 bytes.
+
+  // Tell the PICC we want to transfer the result into block blockAddr.
+  cmdBuffer[0] = PICC_CMD_MF_TRANSFER;
+  cmdBuffer[1] = blockAddr;
+
+  // Adds CRC_A and checks that the response is MF_ACK.
+  return PCD_MIFARE_Transceive(cmdBuffer, 2);
+} // End MIFARE_Transfer()
+
+
+/////////////////////////////////////////////////////////////////////////////////////
+// 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.
+ */
+uint8_t MFRC522::PCD_MIFARE_Transceive(uint8_t *sendData, uint8_t sendLen, bool acceptTimeout)
+{
+  uint8_t result;
+  uint8_t cmdBuffer[18]; // We need room for 16 bytes data and 2 bytes 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(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(PCD_Transceive, waitIRq, cmdBuffer, sendLen, cmdBuffer, &cmdBufferSize, &validBits);
+  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()
+
+
+/*
+ * Translates the SAK (Select Acknowledge) to a PICC type.
+ */
+uint8_t MFRC522::PICC_GetType(uint8_t sak)
+{
+  uint8_t retType = PICC_TYPE_UNKNOWN;
+
+  if (sak & 0x04)
+  { // UID not complete
+    retType = PICC_TYPE_NOT_COMPLETE;
+  }
+  else
+  {
+    switch (sak)
+    {
+      case 0x09: retType = PICC_TYPE_MIFARE_MINI; break;
+      case 0x08: retType = PICC_TYPE_MIFARE_1K;   break;
+      case 0x18: retType = PICC_TYPE_MIFARE_4K;   break;
+      case 0x00: retType = PICC_TYPE_MIFARE_UL;   break;
+      case 0x10:
+      case 0x11: retType = PICC_TYPE_MIFARE_PLUS; break;
+      case 0x01: retType = PICC_TYPE_TNP3XXX;     break;
+      default:
+        if (sak & 0x20)
+        {
+          retType = PICC_TYPE_ISO_14443_4;
+        }
+        else if (sak & 0x40)
+        {
+          retType = PICC_TYPE_ISO_18092;
+        }
+        break;
+    }
+  }
+
+  return (retType);
+} // End PICC_GetType()
+
+/*
+ * Returns a string pointer to the PICC type name.
+ */
+char* MFRC522::PICC_GetTypeName(uint8_t piccType)
+{
+  if(piccType == PICC_TYPE_NOT_COMPLETE)
+  {
+    piccType = MFRC522_MaxPICCs - 1;
+  }
+
+  return((char *) _TypeNamePICC[piccType]);
+} // End PICC_GetTypeName()
+
+/*
+ * Returns a string pointer to a status code name.
+ */
+char* MFRC522::GetStatusCodeName(uint8_t code)
+{
+  return((char *) _ErrorMessage[code]);
+} // End GetStatusCodeName()
+
+/*
+ * Calculates the bit pattern needed for the specified access bits. In the [C1 C2 C3] tupples C1 is MSB (=4) and C3 is LSB (=1).
+ */
+void MFRC522::MIFARE_SetAccessBits(uint8_t *accessBitBuffer,  
+                                   uint8_t g0,                
+                                   uint8_t g1,                
+                                   uint8_t g2,                
+                                   uint8_t g3)
+{
+  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()
+
+/////////////////////////////////////////////////////////////////////////////////////
+// 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.
+ */
+bool MFRC522::PICC_IsNewCardPresent(void)
+{
+  uint8_t bufferATQA[2];
+  uint8_t bufferSize = sizeof(bufferATQA);
+  uint8_t result = PICC_RequestA(bufferATQA, &bufferSize);
+  return ((result == STATUS_OK) || (result == STATUS_COLLISION));
+} // End PICC_IsNewCardPresent()
+
+/*
+ * Simple wrapper around PICC_Select.
+ */
+bool MFRC522::PICC_ReadCardSerial(void)
+{
+  uint8_t result = PICC_Select(&uid);
+  return (result == STATUS_OK);
+} // End PICC_ReadCardSerial()
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/RF/MFRC522.h	Sun May 05 18:17:07 2019 +0000
@@ -0,0 +1,785 @@
+/**
+ * MFRC522.h - Library to use ARDUINO RFID MODULE KIT 13.56 MHZ WITH TAGS SPI W AND R BY COOQROBOT.
+ * Based on code Dr.Leong   ( WWW.B2CQSHOP.COM )
+ * Created by Miguel Balboa (circuitito.com), Jan, 2012.
+ * Rewritten by Soren Thing Andersen (access.thing.dk), fall of 2013 (Translation to English, refactored, comments, anti collision, cascade levels.)
+ * Ported to mbed by Martin Olejar, Dec, 2013
+ *
+ * Please read this file for an overview and then MFRC522.cpp for comments on the specific functions.
+ * Search for "mf-rc522" on ebay.com to purchase the MF-RC522 board.
+ *
+ * There are three hardware components involved:
+ * 1) The micro controller: An Arduino
+ * 2) The PCD (short for Proximity Coupling Device): NXP MFRC522 Contactless Reader IC
+ * 3) The PICC (short for Proximity Integrated Circuit Card): A card or tag using the ISO 14443A interface, eg Mifare or NTAG203.
+ *
+ * The microcontroller and card reader uses SPI for communication.
+ * The protocol is described in the MFRC522 datasheet: http://www.nxp.com/documents/data_sheet/MFRC522.pdf
+ *
+ * The card reader and the tags communicate using a 13.56MHz electromagnetic field.
+ * The protocol is defined in ISO/IEC 14443-3 Identification cards -- Contactless integrated circuit cards -- Proximity cards -- Part 3: Initialization and anticollision".
+ * A free version of the final draft can be found at http://wg8.de/wg8n1496_17n3613_Ballot_FCD14443-3.pdf
+ * Details are found in chapter 6, Type A: Initialization and anticollision.
+ *
+ * If only the PICC UID is wanted, the above documents has all the needed information.
+ * To read and write from MIFARE PICCs, the MIFARE protocol is used after the PICC has been selected.
+ * The MIFARE Classic chips and protocol is described in the datasheets:
+ *    1K:   http://www.nxp.com/documents/data_sheet/MF1S503x.pdf
+ *    4K:   http://www.nxp.com/documents/data_sheet/MF1S703x.pdf
+ *    Mini: http://www.idcardmarket.com/download/mifare_S20_datasheet.pdf
+ * The MIFARE Ultralight chip and protocol is described in the datasheets:
+ *    Ultralight:   http://www.nxp.com/documents/data_sheet/MF0ICU1.pdf
+ *    Ultralight C: http://www.nxp.com/documents/short_data_sheet/MF0ICU2_SDS.pdf
+ *
+ * MIFARE Classic 1K (MF1S503x):
+ *    Has 16 sectors * 4 blocks/sector * 16 bytes/block = 1024 bytes.
+ *    The blocks are numbered 0-63.
+ *    Block 3 in each sector is the Sector Trailer. See http://www.nxp.com/documents/data_sheet/MF1S503x.pdf sections 8.6 and 8.7:
+ *        Bytes 0-5:   Key A
+ *        Bytes 6-8:   Access Bits
+ *        Bytes 9:     User data
+ *        Bytes 10-15: Key B (or user data)
+ *    Block 0 is read only manufacturer data.
+ *    To access a block, an authentication using a key from the block's sector must be performed first.
+ *    Example: To read from block 10, first authenticate using a key from sector 3 (blocks 8-11).
+ *    All keys are set to FFFFFFFFFFFFh at chip delivery.
+ *    Warning: Please read section 8.7 "Memory Access". It includes this text: if the PICC detects a format violation the whole sector is irreversibly blocked.
+ *    To use a block in "value block" mode (for Increment/Decrement operations) you need to change the sector trailer. Use PICC_SetAccessBits() to calculate the bit patterns.
+ * MIFARE Classic 4K (MF1S703x):
+ *    Has (32 sectors * 4 blocks/sector + 8 sectors * 16 blocks/sector) * 16 bytes/block = 4096 bytes.
+ *    The blocks are numbered 0-255.
+ *    The last block in each sector is the Sector Trailer like above.
+ * MIFARE Classic Mini (MF1 IC S20):
+ *    Has 5 sectors * 4 blocks/sector * 16 bytes/block = 320 bytes.
+ *    The blocks are numbered 0-19.
+ *    The last block in each sector is the Sector Trailer like above.
+ *
+ * MIFARE Ultralight (MF0ICU1):
+ *    Has 16 pages of 4 bytes = 64 bytes.
+ *    Pages 0 + 1 is used for the 7-byte UID.
+ *    Page 2 contains the last chech digit for the UID, one byte manufacturer internal data, and the lock bytes (see http://www.nxp.com/documents/data_sheet/MF0ICU1.pdf section 8.5.2)
+ *    Page 3 is OTP, One Time Programmable bits. Once set to 1 they cannot revert to 0.
+ *    Pages 4-15 are read/write unless blocked by the lock bytes in page 2.
+ * MIFARE Ultralight C (MF0ICU2):
+ *    Has 48 pages of 4 bytes = 64 bytes.
+ *    Pages 0 + 1 is used for the 7-byte UID.
+ *    Page 2 contains the last chech digit for the UID, one byte manufacturer internal data, and the lock bytes (see http://www.nxp.com/documents/data_sheet/MF0ICU1.pdf section 8.5.2)
+ *    Page 3 is OTP, One Time Programmable bits. Once set to 1 they cannot revert to 0.
+ *    Pages 4-39 are read/write unless blocked by the lock bytes in page 2.
+ *    Page 40 Lock bytes
+ *    Page 41 16 bit one way counter
+ *    Pages 42-43 Authentication configuration
+ *    Pages 44-47 Authentication key
+ */
+#ifndef MFRC522_h
+#define MFRC522_h
+
+#include "mbed.h"
+
+/**
+* MFRC522 example
+*
+* @code
+* #include "mbed.h"
+* #include "MFRC522.h"
+*
+* //KL25Z Pins for MFRC522 SPI interface
+* #define SPI_MOSI    PTC6
+* #define SPI_MISO    PTC7
+* #define SPI_SCLK    PTC5
+* #define SPI_CS      PTC4
+* // KL25Z Pin for MFRC522 reset
+* #define MF_RESET    PTC3
+* // KL25Z Pins for Debug UART port
+* #define UART_RX     PTA1
+* #define UART_TX     PTA2
+*
+* DigitalOut LedRed   (LED_RED);
+* DigitalOut LedGreen (LED_GREEN);
+*
+* Serial     DebugUART(UART_TX, UART_RX);
+* MFRC522    RfChip   (SPI_MOSI, SPI_MISO, SPI_SCLK, SPI_CS, MF_RESET);
+*
+* int main(void) {
+*   // Set debug UART speed
+*   DebugUART.baud(115200);
+*
+*   // Init. RC522 Chip
+*   RfChip.PCD_Init();
+*
+*   while (true) {
+*     LedRed   = 1;
+*     LedGreen = 1;
+*
+*     // Look for new cards
+*     if ( ! RfChip.PICC_IsNewCardPresent())
+*     {
+*       wait_ms(500);
+*       continue;
+*     }
+*
+*     LedRed   = 0;
+*
+*     // Select one of the cards
+*     if ( ! RfChip.PICC_ReadCardSerial())
+*     {
+*       wait_ms(500);
+*       continue;
+*     }
+*
+*     LedRed   = 1;
+*     LedGreen = 0;
+*
+*     // Print Card UID
+*     printf("Card UID: ");
+*     for (uint8_t i = 0; i < RfChip.uid.size; i++)
+*     {
+*       printf(" %X02", RfChip.uid.uidByte[i]);
+*     }
+*     printf("\n\r");
+*
+*     // Print Card type
+*     uint8_t piccType = RfChip.PICC_GetType(RfChip.uid.sak);
+*     printf("PICC Type: %s \n\r", RfChip.PICC_GetTypeName(piccType));
+*     wait_ms(1000);
+*   }
+* }
+* @endcode
+*/
+
+class MFRC522 {
+public:
+
+  /**
+   * MFRC522 registers (described in chapter 9 of the datasheet).
+   * When using SPI all addresses are shifted one bit left in the "SPI address byte" (section 8.1.2.3)
+   */
+  enum PCD_Register {
+    // Page 0: Command and status
+    //                0x00        // reserved for future use
+    CommandReg      = 0x01 << 1,  // starts and stops command execution
+    ComIEnReg       = 0x02 << 1,  // enable and disable interrupt request control bits
+    DivIEnReg       = 0x03 << 1,  // enable and disable interrupt request control bits
+    ComIrqReg       = 0x04 << 1,  // interrupt request bits
+    DivIrqReg       = 0x05 << 1,  // interrupt request bits
+    ErrorReg        = 0x06 << 1,  // error bits showing the error status of the last command executed
+    Status1Reg      = 0x07 << 1,  // communication status bits
+    Status2Reg      = 0x08 << 1,  // receiver and transmitter status bits
+    FIFODataReg     = 0x09 << 1,  // input and output of 64 byte FIFO buffer
+    FIFOLevelReg    = 0x0A << 1,  // number of bytes stored in the FIFO buffer
+    WaterLevelReg   = 0x0B << 1,  // level for FIFO underflow and overflow warning
+    ControlReg      = 0x0C << 1,  // miscellaneous control registers
+    BitFramingReg   = 0x0D << 1,  // adjustments for bit-oriented frames
+    CollReg         = 0x0E << 1,  // bit position of the first bit-collision detected on the RF interface
+    //                0x0F        // reserved for future use
+
+    // Page 1:Command
+    //                0x10        // reserved for future use
+    ModeReg         = 0x11 << 1,  // defines general modes for transmitting and receiving
+    TxModeReg       = 0x12 << 1,  // defines transmission data rate and framing
+    RxModeReg       = 0x13 << 1,  // defines reception data rate and framing
+    TxControlReg    = 0x14 << 1,  // controls the logical behavior of the antenna driver pins TX1 and TX2
+    TxASKReg        = 0x15 << 1,  // controls the setting of the transmission modulation
+    TxSelReg        = 0x16 << 1,  // selects the internal sources for the antenna driver
+    RxSelReg        = 0x17 << 1,  // selects internal receiver settings
+    RxThresholdReg  = 0x18 << 1,  // selects thresholds for the bit decoder
+    DemodReg        = 0x19 << 1,  // defines demodulator settings
+    //                0x1A        // reserved for future use
+    //                0x1B        // reserved for future use
+    MfTxReg         = 0x1C << 1,  // controls some MIFARE communication transmit parameters
+    MfRxReg         = 0x1D << 1,  // controls some MIFARE communication receive parameters
+    //                0x1E        // reserved for future use
+    SerialSpeedReg  = 0x1F << 1,  // selects the speed of the serial UART interface
+
+    // Page 2: Configuration
+    //                0x20        // reserved for future use
+    CRCResultRegH   = 0x21 << 1,  // shows the MSB and LSB values of the CRC calculation
+    CRCResultRegL   = 0x22 << 1,
+    //                0x23        // reserved for future use
+    ModWidthReg     = 0x24 << 1,  // controls the ModWidth setting?
+    //                0x25        // reserved for future use
+    RFCfgReg        = 0x26 << 1,  // configures the receiver gain
+    GsNReg          = 0x27 << 1,  // selects the conductance of the antenna driver pins TX1 and TX2 for modulation
+    CWGsPReg        = 0x28 << 1,  // defines the conductance of the p-driver output during periods of no modulation
+    ModGsPReg       = 0x29 << 1,  // defines the conductance of the p-driver output during periods of modulation
+    TModeReg        = 0x2A << 1,  // defines settings for the internal timer
+    TPrescalerReg   = 0x2B << 1,  // the lower 8 bits of the TPrescaler value. The 4 high bits are in TModeReg.
+    TReloadRegH     = 0x2C << 1,  // defines the 16-bit timer reload value
+    TReloadRegL     = 0x2D << 1,
+    TCntValueRegH   = 0x2E << 1,  // shows the 16-bit timer value
+    TCntValueRegL   = 0x2F << 1,
+
+    // Page 3:Test Registers
+    //                0x30        // reserved for future use
+    TestSel1Reg     = 0x31 << 1,  // general test signal configuration
+    TestSel2Reg     = 0x32 << 1,  // general test signal configuration
+    TestPinEnReg    = 0x33 << 1,  // enables pin output driver on pins D1 to D7
+    TestPinValueReg = 0x34 << 1,  // defines the values for D1 to D7 when it is used as an I/O bus
+    TestBusReg      = 0x35 << 1,  // shows the status of the internal test bus
+    AutoTestReg     = 0x36 << 1,  // controls the digital self test
+    VersionReg      = 0x37 << 1,  // shows the software version
+    AnalogTestReg   = 0x38 << 1,  // controls the pins AUX1 and AUX2
+    TestDAC1Reg     = 0x39 << 1,  // defines the test value for TestDAC1
+    TestDAC2Reg     = 0x3A << 1,  // defines the test value for TestDAC2
+    TestADCReg      = 0x3B << 1   // shows the value of ADC I and Q channels
+    //                0x3C        // reserved for production tests
+    //                0x3D        // reserved for production tests
+    //                0x3E        // reserved for production tests
+    //                0x3F        // reserved for production tests
+  };
+
+  // MFRC522 commands Described in chapter 10 of the datasheet.
+  enum PCD_Command {
+    PCD_Idle               = 0x00,   // no action, cancels current command execution
+    PCD_Mem                = 0x01,   // stores 25 bytes into the internal buffer
+    PCD_GenerateRandomID   = 0x02,   // generates a 10-byte random ID number
+    PCD_CalcCRC            = 0x03,   // activates the CRC coprocessor or performs a self test
+    PCD_Transmit           = 0x04,   // transmits data from the FIFO buffer
+    PCD_NoCmdChange        = 0x07,   // no command change, can be used to modify the CommandReg register bits without affecting the command, for example, the PowerDown bit
+    PCD_Receive            = 0x08,   // activates the receiver circuits
+    PCD_Transceive         = 0x0C,   // transmits data from FIFO buffer to antenna and automatically activates the receiver after transmission
+    PCD_MFAuthent          = 0x0E,   // performs the MIFARE standard authentication as a reader
+    PCD_SoftReset          = 0x0F    // resets the MFRC522
+  };
+
+  // Commands sent to the PICC.
+  enum PICC_Command {
+    // The commands used by the PCD to manage communication with several PICCs (ISO 14443-3, Type A, section 6.4)
+    PICC_CMD_REQA          = 0x26,   // REQuest command, Type A. Invites PICCs in state IDLE to go to READY and prepare for anticollision or selection. 7 bit frame.
+    PICC_CMD_WUPA          = 0x52,   // 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.
+    PICC_CMD_CT            = 0x88,   // Cascade Tag. Not really a command, but used during anti collision.
+    PICC_CMD_SEL_CL1       = 0x93,   // Anti collision/Select, Cascade Level 1
+    PICC_CMD_SEL_CL2       = 0x95,   // Anti collision/Select, Cascade Level 1
+    PICC_CMD_SEL_CL3       = 0x97,   // Anti collision/Select, Cascade Level 1
+    PICC_CMD_HLTA          = 0x50,   // HaLT command, Type A. Instructs an ACTIVE PICC to go to state HALT.
+
+    // The commands used for MIFARE Classic (from http://www.nxp.com/documents/data_sheet/MF1S503x.pdf, Section 9)
+    // Use PCD_MFAuthent to authenticate access to a sector, then use these commands to read/write/modify the blocks on the sector.
+    // The read/write commands can also be used for MIFARE Ultralight.
+    PICC_CMD_MF_AUTH_KEY_A = 0x60,   // Perform authentication with Key A
+    PICC_CMD_MF_AUTH_KEY_B = 0x61,   // Perform authentication with Key B
+    PICC_CMD_MF_READ       = 0x30,   // Reads one 16 byte block from the authenticated sector of the PICC. Also used for MIFARE Ultralight.
+    PICC_CMD_MF_WRITE      = 0xA0,   // Writes one 16 byte block to the authenticated sector of the PICC. Called "COMPATIBILITY WRITE" for MIFARE Ultralight.
+    PICC_CMD_MF_DECREMENT  = 0xC0,   // Decrements the contents of a block and stores the result in the internal data register.
+    PICC_CMD_MF_INCREMENT  = 0xC1,   // Increments the contents of a block and stores the result in the internal data register.
+    PICC_CMD_MF_RESTORE    = 0xC2,   // Reads the contents of a block into the internal data register.
+    PICC_CMD_MF_TRANSFER   = 0xB0,   // Writes the contents of the internal data register to a block.
+
+    // The commands used for MIFARE Ultralight (from http://www.nxp.com/documents/data_sheet/MF0ICU1.pdf, Section 8.6)
+    // The PICC_CMD_MF_READ and PICC_CMD_MF_WRITE can also be used for MIFARE Ultralight.
+    PICC_CMD_UL_WRITE      = 0xA2    // Writes one 4 byte page to the PICC.
+  };
+
+  // MIFARE constants that does not fit anywhere else
+  enum MIFARE_Misc {
+    MF_ACK                 = 0xA,    // The MIFARE Classic uses a 4 bit ACK/NAK. Any other value than 0xA is NAK.
+    MF_KEY_SIZE            = 6       // A Mifare Crypto1 key is 6 bytes.
+  };
+
+  // PICC types we can detect. Remember to update PICC_GetTypeName() if you add more.
+  enum PICC_Type {
+    PICC_TYPE_UNKNOWN      = 0,
+    PICC_TYPE_ISO_14443_4  = 1,  // PICC compliant with ISO/IEC 14443-4
+    PICC_TYPE_ISO_18092    = 2,  // PICC compliant with ISO/IEC 18092 (NFC)
+    PICC_TYPE_MIFARE_MINI  = 3,  // MIFARE Classic protocol, 320 bytes
+    PICC_TYPE_MIFARE_1K    = 4,  // MIFARE Classic protocol, 1KB
+    PICC_TYPE_MIFARE_4K    = 5,  // MIFARE Classic protocol, 4KB
+    PICC_TYPE_MIFARE_UL    = 6,  // MIFARE Ultralight or Ultralight C
+    PICC_TYPE_MIFARE_PLUS  = 7,  // MIFARE Plus
+    PICC_TYPE_TNP3XXX      = 8,  // Only mentioned in NXP AN 10833 MIFARE Type Identification Procedure
+    PICC_TYPE_NOT_COMPLETE = 255 // SAK indicates UID is not complete.
+  };
+
+  // Return codes from the functions in this class. Remember to update GetStatusCodeName() if you add more.
+  enum StatusCode {
+    STATUS_OK              = 1,  // Success
+    STATUS_ERROR           = 2,  // Error in communication
+    STATUS_COLLISION       = 3,  // Collision detected
+    STATUS_TIMEOUT         = 4,  // Timeout in communication.
+    STATUS_NO_ROOM         = 5,  // A buffer is not big enough.
+    STATUS_INTERNAL_ERROR  = 6,  // Internal error in the code. Should not happen ;-)
+    STATUS_INVALID         = 7,  // Invalid argument.
+    STATUS_CRC_WRONG       = 8,  // The CRC_A does not match
+    STATUS_MIFARE_NACK     = 9   // A MIFARE PICC responded with NAK.
+  };
+
+  // A struct used for passing the UID of a PICC.
+  typedef struct {
+    uint8_t    size;     // Number of bytes in the UID. 4, 7 or 10.
+    uint8_t    uidByte[10];
+    uint8_t    sak;      // The SAK (Select acknowledge) byte returned from the PICC after successful selection.
+  } Uid;
+
+  // A struct used for passing a MIFARE Crypto1 key
+  typedef struct {
+    uint8_t    keyByte[MF_KEY_SIZE];
+  } MIFARE_Key;
+
+  // Member variables
+  Uid uid;                // Used by PICC_ReadCardSerial().
+
+  // Size of the MFRC522 FIFO
+  static const uint8_t FIFO_SIZE = 64;   // The FIFO is 64 bytes.
+
+  /**
+  * MFRC522 constructor
+  *
+  * @param mosi  SPI MOSI pin
+  * @param miso  SPI MISO pin
+  * @param sclk  SPI SCLK pin
+  * @param cs    SPI CS pin
+  * @param reset Reset pin
+  */
+  MFRC522(PinName mosi, PinName miso, PinName sclk, PinName cs, PinName reset);
+
+  /**
+  * MFRC522 destructor
+  */
+  ~MFRC522();
+  
+
+  // ************************************************************************************
+  //! @name Functions for manipulating the MFRC522
+  // ************************************************************************************
+  //@{
+
+  /**
+  * Initializes the MFRC522 chip.
+  */
+  void    PCD_Init           (void);
+
+  /**
+  * Performs a soft reset on the MFRC522 chip and waits for it to be ready again.
+  */
+  void    PCD_Reset          (void);
+
+  /**
+  * Turns the antenna on by enabling pins TX1 and TX2.
+  * After a reset these pins disabled.
+  */
+  void    PCD_AntennaOn      (void);
+
+  /**
+  * Writes a byte to the specified register in the MFRC522 chip.
+  * The interface is described in the datasheet section 8.1.2.
+  *
+  * @param reg   The register to write to. One of the PCD_Register enums.
+  * @param value The value to write.
+  */
+  void    PCD_WriteRegister  (uint8_t reg, uint8_t value);
+
+  /**
+  * Writes a number of bytes to the specified register in the MFRC522 chip.
+  * The interface is described in the datasheet section 8.1.2.
+  *
+  * @param reg    The register to write to. One of the PCD_Register enums.
+  * @param count  The number of bytes to write to the register
+  * @param values The values to write. Byte array.
+  */
+  void    PCD_WriteRegister  (uint8_t reg, uint8_t count, uint8_t *values);
+
+  /**
+  * Reads a byte from the specified register in the MFRC522 chip.
+  * The interface is described in the datasheet section 8.1.2.
+  *
+  * @param reg The register to read from. One of the PCD_Register enums.
+  * @returns Register value
+  */
+  uint8_t PCD_ReadRegister   (uint8_t reg);
+
+  /**
+  * Reads a number of bytes from the specified register in the MFRC522 chip.
+  * The interface is described in the datasheet section 8.1.2.
+  *
+  * @param reg     The register to read from. One of the PCD_Register enums.
+  * @param count   The number of bytes to read.
+  * @param values  Byte array to store the values in.
+  * @param rxAlign Only bit positions rxAlign..7 in values[0] are updated.
+  */
+  void    PCD_ReadRegister   (uint8_t reg, uint8_t count, uint8_t *values, uint8_t rxAlign = 0);
+
+  /**
+  * Sets the bits given in mask in register reg.
+  *
+  * @param reg  The register to update. One of the PCD_Register enums.
+  * @param mask The bits to set.
+  */
+  void    PCD_SetRegisterBits(uint8_t reg, uint8_t mask);
+
+  /**
+  * Clears the bits given in mask from register reg.
+  *
+  * @param reg  The register to update. One of the PCD_Register enums.
+  * @param mask The bits to clear.
+  */
+  void    PCD_ClrRegisterBits(uint8_t reg, uint8_t mask);
+
+  /**
+  * Use the CRC coprocessor in the MFRC522 to calculate a CRC_A.
+  *
+  * @param data   Pointer to the data to transfer to the FIFO for CRC calculation.
+  * @param length The number of bytes to transfer.
+  * @param result Pointer to result buffer. Result is written to result[0..1], low byte first.
+  * @return STATUS_OK on success, STATUS_??? otherwise.
+  */
+  uint8_t PCD_CalculateCRC   (uint8_t *data, uint8_t length, uint8_t *result);
+
+  /**
+   * Executes the Transceive command.
+   * CRC validation can only be done if backData and backLen are specified.
+   *
+   * @param sendData Pointer to the data to transfer to the FIFO.
+   * @param sendLen  Number of bytes to transfer to the FIFO.
+   * @param backData NULL or pointer to buffer if data should be read back after executing the command.
+   * @param backLen  Max number of bytes to write to *backData. Out: The number of bytes returned.
+   * @param validBits The number of valid bits in the last byte. 0 for 8 valid bits. Default NULL.
+   * @param rxAlign  Defines the bit position in backData[0] for the first bit received. Default 0.
+   * @param checkCRC True => The last two bytes of the response is assumed to be a CRC_A that must be validated.
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t PCD_TransceiveData (uint8_t *sendData,
+                              uint8_t sendLen,
+                              uint8_t *backData,
+                              uint8_t *backLen,
+                              uint8_t *validBits = NULL,
+                              uint8_t rxAlign    = 0,
+                              bool    checkCRC   = false);
+
+
+  /**
+   * Transfers data to the MFRC522 FIFO, executes a commend, waits for completion and transfers data back from the FIFO.
+   * CRC validation can only be done if backData and backLen are specified.
+   *
+   * @param command   The command to execute. One of the PCD_Command enums.
+   * @param waitIRq   The bits in the ComIrqReg register that signals successful completion of the command.
+   * @param sendData  Pointer to the data to transfer to the FIFO.
+   * @param sendLen   Number of bytes to transfer to the FIFO.
+   * @param backData  NULL or pointer to buffer if data should be read back after executing the command.
+   * @param backLen   In: Max number of bytes to write to *backData. Out: The number of bytes returned.
+   * @param validBits In/Out: The number of valid bits in the last byte. 0 for 8 valid bits.
+   * @param rxAlign   In: Defines the bit position in backData[0] for the first bit received. Default 0.
+   * @param checkCRC  In: True => The last two bytes of the response is assumed to be a CRC_A that must be validated.
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t PCD_CommunicateWithPICC(uint8_t command,
+                                  uint8_t waitIRq,
+                                  uint8_t *sendData,
+                                  uint8_t sendLen,
+                                  uint8_t *backData  = NULL,
+                                  uint8_t *backLen   = NULL,
+                                  uint8_t *validBits = NULL,
+                                  uint8_t rxAlign    = 0,
+                                  bool    checkCRC   = false);
+
+  /**
+   * 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.
+   *
+   * @param bufferATQA  The buffer to store the ATQA (Answer to request) in
+   * @param bufferSize  Buffer size, at least two bytes. Also number of bytes returned if STATUS_OK.
+   * 
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t PICC_RequestA      (uint8_t *bufferATQA, uint8_t *bufferSize);
+  
+  /**
+   * 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.
+   *
+   * @param bufferATQA  The buffer to store the ATQA (Answer to request) in
+   * @param bufferSize  Buffer size, at least two bytes. Also number of bytes returned if STATUS_OK.
+   * 
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */  
+  uint8_t PICC_WakeupA       (uint8_t *bufferATQA, uint8_t *bufferSize);
+  
+  /**
+   * 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.
+   *
+   * @param command     The command to send - PICC_CMD_REQA or PICC_CMD_WUPA
+   * @param bufferATQA  The buffer to store the ATQA (Answer to request) in
+   * @param bufferSize  Buffer size, at least two bytes. Also number of bytes returned if STATUS_OK.
+   * 
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */  
+  uint8_t PICC_REQA_or_WUPA  (uint8_t command, uint8_t *bufferATQA, uint8_t *bufferSize);
+  
+  /**
+   * 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 bytes.
+   * Only 4 bytes can be specified in a SELECT command, so for the longer UIDs two or three iterations are used:
+   *
+   *   UID size        Number of UID bytes                Cascade levels                Example of PICC
+   *   ========        ===================                ==============                ===============
+   *   single                   4                                1                      MIFARE Classic
+   *   double                   7                                2                      MIFARE Ultralight
+   *   triple                  10                                3                      Not currently in use?
+   *
+   *
+   * @param uid        Pointer to Uid struct. Normally output, but can also be used to supply a known UID.
+   * @param validBits  The number of known UID bits supplied in *uid. Normally 0. If set you must also supply uid->size.
+   *   
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t PICC_Select        (Uid *uid, uint8_t validBits = 0);
+  
+  /**
+   * Instructs a PICC in state ACTIVE(*) to go to state HALT.
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */  
+  uint8_t PICC_HaltA         (void);
+  
+  // ************************************************************************************
+  //@}
+
+
+  // ************************************************************************************
+  //! @name 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.
+   *
+   * @param command    PICC_CMD_MF_AUTH_KEY_A or PICC_CMD_MF_AUTH_KEY_B
+   * @param blockAddr  The block number. See numbering in the comments in the .h file.
+   * @param key        Pointer to the Crypteo1 key to use (6 bytes)
+   * @param uid        Pointer to Uid struct. The first 4 bytes of the UID is used.
+   * 
+   * @return STATUS_OK on success, STATUS_??? otherwise. Probably STATUS_TIMEOUT if you supply the wrong key.
+   */
+  uint8_t PCD_Authenticate   (uint8_t command, uint8_t blockAddr, MIFARE_Key *key, Uid *uid);
+  
+  /**
+   * 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    (void);
+  
+  /**
+   * Reads 16 bytes (+ 2 bytes 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 bytes 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 bytes because a CRC_A is also returned.
+   * Checks the CRC_A before returning STATUS_OK.
+   *
+   * @param blockAddr  MIFARE Classic: The block (0-0xff) number. MIFARE Ultralight: The first page to return data from.
+   * @param buffer     The buffer to store the data in
+   * @param bufferSize Buffer size, at least 18 bytes. Also number of bytes returned if STATUS_OK.
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t MIFARE_Read        (uint8_t blockAddr, uint8_t *buffer, uint8_t *bufferSize);
+  
+  /**
+   * Writes 16 bytes to the active PICC.
+   * 
+   * For MIFARE Classic the sector containing the block must be authenticated before calling this function.
+   * 
+   * For MIFARE Ultralight the opretaion is called "COMPATIBILITY WRITE".
+   * Even though 16 bytes are transferred to the Ultralight PICC, only the least significant 4 bytes (bytes 0 to 3)
+   * are written to the specified address. It is recommended to set the remaining bytes 04h to 0Fh to all logic 0.
+   *
+   * @param blockAddr  MIFARE Classic: The block (0-0xff) number. MIFARE Ultralight: The page (2-15) to write to.
+   * @param buffer     The 16 bytes to write to the PICC
+   * @param bufferSize Buffer size, must be at least 16 bytes. Exactly 16 bytes are written.
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+ */
+  uint8_t MIFARE_Write       (uint8_t blockAddr, uint8_t *buffer, uint8_t bufferSize);
+  
+  /**
+   * Writes a 4 byte page to the active MIFARE Ultralight PICC.
+   * 
+   * @param page       The page (2-15) to write to.
+   * @param buffer     The 4 bytes to write to the PICC
+   * @param bufferSize Buffer size, must be at least 4 bytes. Exactly 4 bytes are written.
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t MIFARE_UltralightWrite(uint8_t page, uint8_t *buffer, uint8_t bufferSize);
+   
+  /**
+   * 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.
+   *
+   * @param blockAddr The block (0-0xff) number.
+   * @param delta     This number is subtracted from the value of block blockAddr.
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t MIFARE_Decrement   (uint8_t blockAddr, uint32_t delta);
+  
+  /**
+   * 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.
+   * 
+   * @param blockAddr The block (0-0xff) number.
+   * @param delta     This number is added to the value of block blockAddr.
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t MIFARE_Increment   (uint8_t blockAddr, uint32_t delta);
+  
+  /**
+   * 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.
+   * 
+   * @param blockAddr The block (0-0xff) number.
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t MIFARE_Restore     (uint8_t blockAddr);
+  
+  /**
+   * 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].
+   * 
+   * @param blockAddr The block (0-0xff) number.
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t MIFARE_Transfer    (uint8_t blockAddr);
+  
+  // ************************************************************************************
+  //@}
+
+
+  // ************************************************************************************
+  //! @name 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.
+   * 
+   * @param sendData      Pointer to the data to transfer to the FIFO. Do NOT include the CRC_A.
+   * @param sendLen       Number of bytes in sendData.
+   * @param acceptTimeout True => A timeout is also success
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t PCD_MIFARE_Transceive(uint8_t *sendData, uint8_t sendLen, bool acceptTimeout = false);
+  
+  /**
+   * Translates the SAK (Select Acknowledge) to a PICC type.
+   * 
+   * @param sak The SAK byte returned from PICC_Select().
+   *
+   * @return PICC_Type
+   */
+  uint8_t PICC_GetType         (uint8_t sak);
+  
+  /**
+   * Returns a string pointer to the PICC type name.
+   * 
+   * @param type One of the PICC_Type enums.
+   *
+   * @return A string pointer to the PICC type name.
+   */
+  char*   PICC_GetTypeName     (uint8_t type);
+  
+  /**
+   * Returns a string pointer to a status code name.
+   * 
+   * @param code One of the StatusCode enums.
+   *
+   * @return A string pointer to a status code name.
+   */
+  char*   GetStatusCodeName    (uint8_t code);
+  
+  /**
+   * Calculates the bit pattern needed for the specified access bits. In the [C1 C2 C3] tupples C1 is MSB (=4) and C3 is LSB (=1).
+   * 
+   * @param accessBitBuffer Pointer to byte 6, 7 and 8 in the sector trailer. Bytes [0..2] will be set.
+   * @param g0              Access bits [C1 C2 C3] for block 0 (for sectors 0-31) or blocks 0-4 (for sectors 32-39)
+   * @param g1              Access bits [C1 C2 C3] for block 1 (for sectors 0-31) or blocks 5-9 (for sectors 32-39)
+   * @param g2              Access bits [C1 C2 C3] for block 2 (for sectors 0-31) or blocks 10-14 (for sectors 32-39)
+   * @param g3              Access bits [C1 C2 C3] for the sector trailer, block 3 (for sectors 0-31) or block 15 (for sectors 32-39)
+   */
+  void    MIFARE_SetAccessBits (uint8_t *accessBitBuffer,
+                                uint8_t g0,
+                                uint8_t g1,
+                                uint8_t g2,
+                                uint8_t g3);
+                                
+  // ************************************************************************************
+  //@}
+
+
+  // ************************************************************************************
+  //! @name 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(void);
+  
+  /**
+   * 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  (void);
+  
+  // ************************************************************************************
+  //@}
+
+
+private:
+  SPI              m_SPI;
+  DigitalOut       m_CS;
+  DigitalOut       m_RESET;
+
+  /**
+   * Helper function for the two-step MIFARE Classic protocol operations Decrement, Increment and Restore.
+   * 
+   * @param command    The command to use
+   * @param blockAddr  The block (0-0xff) number.
+   * @param data       The data to transfer in step 2
+   *
+   * @return STATUS_OK on success, STATUS_??? otherwise.
+   */
+  uint8_t MIFARE_TwoStepHelper(uint8_t command, uint8_t blockAddr, uint32_t data);
+};
+
+#endif
--- a/main.cpp	Sun May 05 17:01:42 2019 +0000
+++ b/main.cpp	Sun May 05 18:17:07 2019 +0000
@@ -1,22 +1,74 @@
 #include "mbed.h"
 #include "QEI.h"
+#include "MFRC522.h"
+
+#define MF_RESET    D8
 
 Serial pc(USBTX, USBRX);
 
-QEI temp_dial(D11, D12, A1, 50, QEI::X4_ENCODING);
+MFRC522    RfChip   (D11, D12, D13, D10, D8);
+
+QEI temp_dial(A3, A4, A1, 50, QEI::X4_ENCODING);
 BusIn joy_bus{D3, D4, D5, D6};
 BusIn button_bus{D7, D9};
 DigitalIn a(D7),b(D9),c(D3),d(D4),e(D5),f(D6); //Dummy pin for pulling
 
-int data[8];
+
+int data[8],RFID_Tag = 0;
+unsigned int sum_x = 0;
 
 void init_();
+void RFID_Tag_Read();
 
 int main() {
-    pc.baud(9600);
+    
+    
     uint16_t pulse = 0;
     init_();
+    
     while(1){
+       //  continue;
+    if ( ! RfChip.PICC_IsNewCardPresent())
+    {
+      continue;
+    }
+
+    if ( ! RfChip.PICC_ReadCardSerial())
+    {
+     continue;
+    }
+
+    for (uint8_t i = 0; i < RfChip.uid.size; i++)
+    {
+      sum_x += RfChip.uid.uidByte[i];
+      //pc.printf(" %X02", RfChip.uid.uidByte[i]);
+    }
+    /*pc.printf("\n\r");
+    pc.printf(" UID_sum %d", sum_x);
+    pc.printf("\n\r");*/
+    
+    if(sum_x == 461)RFID_Tag = 1;
+    else if(sum_x == 538)RFID_Tag = 2;
+    else if(sum_x == 598)RFID_Tag = 3;
+    else if(sum_x == 548)RFID_Tag = 4;
+    else RFID_Tag = 0;
+    
+     pc.printf("RFID_Tag : %d",RFID_Tag);
+     pc.printf("\n\r");
+    sum_x = 0;
+    uint8_t piccType = RfChip.PICC_GetType(RfChip.uid.sak);
+    
+  // continue;
+        
+        
+        
+        
+        
+        
+        
+        
+        
+        
         pulse = temp_dial.getPulses()/2;
         if (pulse >= 350)
             pulse = 350;
@@ -47,17 +99,27 @@
         data[0]= 0x00;
         */
         
-        for (int i = 0; i<=7; i++)
-            pc.putc(data[i]);
+       // for (int i = 0; i<=7; i++)
+       //     pc.putc(data[i]);
     }
 }
 
 
 void init_(){
+    pc.baud(9600);
+    
+    RfChip.PCD_Init();
+    
     a.mode(PullDown);
     b.mode(PullDown);
     c.mode(PullDown);
     d.mode(PullDown);
     e.mode(PullDown);
     f.mode(PullDown);   
-}
\ No newline at end of file
+}
+
+void RFID_Tag_Read()
+{
+   
+   
+    }
\ No newline at end of file