Get SPI SS/CS pin automatically

MFRC522.cpp

@@ -16,6 +16,14 @@
 MFRC522::MFRC522() {
 } // End constructor
 
+/**
+ * Constructor.
+ * Prepares the output pins.
+ */
+MFRC522::MFRC522(	byte resetPowerDownPin	///< Arduino pin connected to MFRC522's reset and power down input (Pin 6, NRSTPD, active low)
+				): MFRC522(SS, resetPowerDownPin) {
+} // End constructor
+
 /**
  * Constructor.
  * Prepares the output pins.
@@ -217,6 +225,14 @@ 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 resetPowerDownPin	///< Arduino pin connected to MFRC522's reset and power down input (Pin 6, NRSTPD, active low)
+					) {
+	PCD_Init(SS, resetPowerDownPin);
+} // End PCD_Init()
+
 /**
  * Initializes the MFRC522 chip.
  */

MFRC522.h

@@ -322,6 +322,7 @@ public:
 	// Functions for setting up the Arduino
 	/////////////////////////////////////////////////////////////////////////////////////
 	MFRC522();
+	MFRC522(byte resetPowerDownPin);
 	MFRC522(byte chipSelectPin, byte resetPowerDownPin);
 	
 	/////////////////////////////////////////////////////////////////////////////////////
@@ -340,6 +341,7 @@ public:
 	// Functions for manipulating the MFRC522
 	/////////////////////////////////////////////////////////////////////////////////////
 	void PCD_Init();
+	void PCD_Init(byte resetPowerDownPin);
 	void PCD_Init(byte chipSelectPin, byte resetPowerDownPin);
 	void PCD_Reset();
 	void PCD_AntennaOn();