New constructor and PCD_Init() method to allow defining arrays of readers.

MFRC522.cpp

@@ -10,6 +10,12 @@
 /////////////////////////////////////////////////////////////////////////////////////
 // Functions for setting up the Arduino
 /////////////////////////////////////////////////////////////////////////////////////
+/**
+ * Constructor.
+ */
+MFRC522::MFRC522() {
+  
+} // End constructor
 
 /**
  * Constructor.
@@ -39,7 +45,7 @@ void MFRC522::setSPIConfig() {
  * 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(	byte reg,		///< The register to write to. One of the PCD_Register enums.
+void MFRC522::PCD_WriteRegister(byte reg,		///< The register to write to. One of the PCD_Register enums.
 				byte value		///< The value to write.
 				) {
 	digitalWrite(_chipSelectPin, LOW);		// Select slave
@@ -52,7 +58,7 @@ void MFRC522::PCD_WriteRegister(	byte reg,		///< The register to write to. One o
  * 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(	byte reg,		///< The register to write to. One of the PCD_Register enums.
+void MFRC522::PCD_WriteRegister(byte reg,		///< The register to write to. One of the PCD_Register enums.
 				byte count,		///< The number of bytes to write to the register
 				byte *values	///< The values to write. Byte array.
 				) {
@@ -216,6 +222,46 @@ void MFRC522::PCD_Init() {
 	PCD_AntennaOn();						// Enable the antenna driver pins TX1 and TX2 (they were disabled by the reset)
 } // End PCD_Init()
 
+/**
+ * Initializes the MFRC522 chip.
+ */
+void MFRC522::PCD_Init(byte chipSelectPin, byte resetPowerDownPin) {
+	_chipSelectPin = chipSelectPin;
+	_resetPowerDownPin = resetPowerDownPin;
+	
+	// Set the chipSelectPin as digital output, do not select the slave yet
+	pinMode(_chipSelectPin, OUTPUT);
+	digitalWrite(_chipSelectPin, HIGH);
+
+	// Set the resetPowerDownPin as digital output, do not reset or power down.
+	pinMode(_resetPowerDownPin, OUTPUT);
+
+	// Set SPI bus to work with MFRC522 chip.
+	setSPIConfig();
+
+	if (digitalRead(_resetPowerDownPin) == LOW) {	//The MFRC522 chip is in power down mode.
+		digitalWrite(_resetPowerDownPin, HIGH);		// Exit power down mode. This triggers a hard reset.
+		// Section 8.8.2 in the datasheet says the oscillator start-up time is the start up time of the crystal + 37,74<37>s. Let us be generous: 50ms.
+		delay(50);
+	}
+	else { // Perform a soft reset
+		PCD_Reset();
+	}
+	
+	// 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 25<32>s.
+	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_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.
  */
@@ -360,7 +406,7 @@ bool MFRC522::PCD_PerformSelfTest() {
  * 
  * @return STATUS_OK on success, STATUS_??? otherwise.
  */
-byte MFRC522::PCD_TransceiveData(	byte *sendData,		///< Pointer to the data to transfer to the FIFO.
+byte MFRC522::PCD_TransceiveData(byte *sendData,		///< Pointer to the data to transfer to the FIFO.
 					byte sendLen,		///< Number of bytes to transfer to the FIFO.
 					byte *backData,		///< NULL or pointer to buffer if data should be read back after executing the command.
 					byte *backLen,		///< In: Max number of bytes to write to *backData. Out: The number of bytes returned.

MFRC522.h

@@ -319,6 +319,7 @@ public:
 	/////////////////////////////////////////////////////////////////////////////////////
 	// Functions for setting up the Arduino
 	/////////////////////////////////////////////////////////////////////////////////////
+	MFRC522();
 	MFRC522(byte chipSelectPin, byte resetPowerDownPin);
 	void setSPIConfig();
 	
@@ -338,6 +339,7 @@ public:
 	// Functions for manipulating the MFRC522
 	/////////////////////////////////////////////////////////////////////////////////////
 	void PCD_Init();
+	void PCD_Init(byte, byte);
 	void PCD_Reset();
 	void PCD_AntennaOn();
 	void PCD_AntennaOff();

examples/ReadUidMultiReader/ReadUidMultiReader.ino

@@ -0,0 +1,90 @@
+/**
+ * ----------------------------------------------------------------------------
+ * This is a MFRC522 library example; see https://github.com/miguelbalboa/rfid
+ * for further details and other examples.
+ *
+ * NOTE: The library file MFRC522.h has a lot of useful info. Please read it.
+ *
+ * Released into the public domain.
+ * ----------------------------------------------------------------------------
+ * This sample shows how to read and write data blocks on a MIFARE Classic PICC
+ * (= card/tag).
+ *
+ * Typical pin layout used:
+ * -----------------------------------------------------------------------------------------
+ *             MFRC522      Arduino       Arduino   Arduino    Arduino          Arduino
+ *             Reader/PCD   Uno           Mega      Nano v3    Leonardo/Micro   Pro Micro
+ * Signal      Pin          Pin           Pin       Pin        Pin              Pin
+ * -----------------------------------------------------------------------------------------
+ * RST/Reset   RST          9             5         D9         RESET/ICSP-5     RST
+ * SPI SS 1    SDA(SS)      5             53        D10        10               10
+ * SPI SS 2    SDA(SS)      2             53        D10        10               10
+ * SPI MOSI    MOSI         11 / ICSP-4   51        D11        ICSP-4           16
+ * SPI MISO    MISO         12 / ICSP-1   50        D12        ICSP-1           14
+ * SPI SCK     SCK          13 / ICSP-3   52        D13        ICSP-3           15
+ *
+ */
+
+#include <SPI.h>
+#include <MFRC522.h>
+
+#define RST_PIN         9           // Configurable, see typical pin layout above
+#define SS_1_PIN        5          // Configurable, see typical pin layout above
+#define SS_2_PIN        2          // Configurable, see typical pin layout above
+
+#define NR_OF_READERS   2
+
+byte ssPins[] = {SS_1_PIN, SS_2_PIN};
+
+MFRC522 mfrc522[NR_OF_READERS];   // Create MFRC522 instance.
+
+MFRC522::MIFARE_Key key;
+
+/**
+ * Initialize.
+ */
+void setup() {
+  Serial.begin(115200); // Initialize serial communications with the PC
+  while (!Serial);    // Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)
+
+  SPI.begin();        // Init SPI bus
+
+  for (uint8_t reader = 0; reader < NR_OF_READERS; reader++) {
+    mfrc522[reader].PCD_Init(ssPins[reader], RST_PIN); // Init each MFRC522 card
+  }
+}
+
+/**
+ * Main loop.
+ */
+void loop() {
+
+  for (uint8_t reader = 0; reader < NR_OF_READERS; reader++) {
+    // Look for new cards
+    if (mfrc522[reader].PICC_IsNewCardPresent() && mfrc522[reader].PICC_ReadCardSerial()) {
+
+      // Show some details of the PICC (that is: the tag/card)
+      Serial.print(F("Card UID:"));
+      dump_byte_array(mfrc522[reader].uid.uidByte, mfrc522[reader].uid.size);
+      Serial.println();
+      Serial.print(F("PICC type: "));
+      byte piccType = mfrc522[reader].PICC_GetType(mfrc522[reader].uid.sak);
+      Serial.println(mfrc522[reader].PICC_GetTypeName(piccType));
+
+      // Halt PICC
+      mfrc522[reader].PICC_HaltA();
+      // Stop encryption on PCD
+      mfrc522[reader].PCD_StopCrypto1();
+    } //if (mfrc522[reader].PICC_IsNewC
+  } //for(uint8_t reader
+}
+
+/**
+ * Helper routine to dump a byte array as hex values to Serial.
+ */
+void dump_byte_array(byte *buffer, byte bufferSize) {
+  for (byte i = 0; i < bufferSize; i++) {
+    Serial.print(buffer[i] < 0x10 ? " 0" : " ");
+    Serial.print(buffer[i], HEX);
+  }
+}