fix typo

Also, be more scientific about the timeouts rather than using a set
number of loops, the time of which depends on the value of the
MRFC522_SPICLOCK as well as F_CPU. Instead, use a set number of
milliseconds as a deadline.

examples/ChangeUID/ChangeUID.ino

@@ -20,6 +20,8 @@
  * 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
+ *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
  */
 
 #include <SPI.h>

examples/DumpInfo/DumpInfo.ino

@@ -31,6 +31,8 @@
  * 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
+ *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
  */
 
 #include <SPI.h>

examples/FixBrickedUID/FixBrickedUID.ino

@@ -20,6 +20,8 @@
  * 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
+ *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
  */
 
 #include <SPI.h>

examples/MifareClassicValueBlock/MifareClassicValueBlock.ino

@@ -25,6 +25,8 @@
  * 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
+ *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
  * 
  */
 

examples/MinimalInterrupt/MinimalInterrupt.ino

@@ -23,6 +23,8 @@
  * 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
+ *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
  * 
  */
 

examples/RFID-Cloner/RFID-Cloner.ino

@@ -18,6 +18,8 @@
  * SPI MISO    MISO         12 / ICSP-1   50        D12        ICSP-1           14
  * SPI SCK     SCK          13 / ICSP-3   52        D13        ICSP-3           15
  *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
+ *
  */
 
 #include <SPI.h>

examples/ReadAndWrite/ReadAndWrite.ino

@@ -25,6 +25,8 @@
  * SPI MISO    MISO         12 / ICSP-1   50        D12        ICSP-1           14
  * SPI SCK     SCK          13 / ICSP-3   52        D13        ICSP-3           15
  *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
+ *
  */
 
 #include <SPI.h>

examples/ReadNUID/ReadNUID.ino

@@ -26,6 +26,8 @@
  * 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
+ *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
  */
 
 #include <SPI.h>

examples/ReadUidMultiReader/ReadUidMultiReader.ino

@@ -25,6 +25,8 @@
  * SPI MISO    MISO         12 / ICSP-1   50        D12        ICSP-1           14
  * SPI SCK     SCK          13 / ICSP-3   52        D13        ICSP-3           15
  *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
+ *
  */
 
 #include <SPI.h>

examples/firmware_check/firmware_check.ino

@@ -21,6 +21,8 @@
  * 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
+ *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
  */
 
 #include <SPI.h>

examples/rfid_default_keys/rfid_default_keys.ino

@@ -23,6 +23,8 @@
  * SPI MISO    MISO         12 / ICSP-1   50        D12        ICSP-1           14
  * SPI SCK     SCK          13 / ICSP-3   52        D13        ICSP-3           15
  *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
+ *
  */
 
 #include <SPI.h>

examples/rfid_read_personal_data/rfid_read_personal_data.ino

@@ -17,6 +17,8 @@
  * 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
+ *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
 */
 
 #include <SPI.h>

examples/rfid_write_personal_data/rfid_write_personal_data.ino

@@ -12,6 +12,8 @@
  * SPI MISO    MISO         12 / ICSP-1   50        D12        ICSP-1           14
  * SPI SCK     SCK          13 / ICSP-3   52        D13        ICSP-3           15
  *
+ * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
+ *
  * Hardware required:
  * Arduino
  * PCD (Proximity Coupling Device): NXP MFRC522 Contactless Reader IC

src/MFRC522.cpp

@@ -163,11 +163,13 @@ MFRC522::StatusCode MFRC522::PCD_CalculateCRC(	byte *data,		///< In: Pointer to
 	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 17.73μs.
-	// TODO check/modify for other architectures than Arduino Uno 16bit
+	// Wait for the CRC calculation to complete. Check for the register to
+	// indicate that the CRC calculation is complete in a loop. If the
+	// calculation is not indicated as complete in ~90ms, then time out
+	// the operation.
+	const uint32_t deadline = millis() + 89;
 
-	// Wait for the CRC calculation to complete. Each iteration of the while-loop takes 17.73us.
-	for (uint16_t i = 5000; i > 0; i--) {
+	do {
 		// DivIrqReg[7..0] bits are: Set2 reserved reserved MfinActIRq reserved CRCIRq reserved reserved
 		byte n = PCD_ReadRegister(DivIrqReg);
 		if (n & 0x04) {									// CRCIRq bit set - calculation done
@@ -177,8 +179,11 @@ MFRC522::StatusCode MFRC522::PCD_CalculateCRC(	byte *data,		///< In: Pointer to
 			result[1] = PCD_ReadRegister(CRCResultRegH);
 			return STATUS_OK;
 		}
+		yield();
 	}
-	// 89ms passed and nothing happend. Communication with the MFRC522 might be down.
+	while (static_cast<uint32_t> (millis()) < deadline);
+
+	// 89ms passed and nothing happened. Communication with the MFRC522 might be down.
 	return STATUS_TIMEOUT;
 } // End PCD_CalculateCRC()
 
@@ -422,6 +427,7 @@ void MFRC522::PCD_SoftPowerUp(){
 		if(!(val & (1<<4))){ // if powerdown bit is 0 
 			break;// wake up procedure is finished 
 		}
+		yield();
 	}
 }
 
@@ -477,22 +483,32 @@ MFRC522::StatusCode MFRC522::PCD_CommunicateWithPICC(	byte command,		///< The co
 		PCD_SetRegisterBitMask(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 17.86μs.
-	// TODO check/modify for other architectures than Arduino Uno 16bit
-	uint16_t i;
-	for (i = 2000; i > 0; i--) {
+	// In PCD_Init() we set the TAuto flag in TModeReg. This means the timer
+	// automatically starts when the PCD stops transmitting.
+	//
+	// Wait here for the command to complete. The bits specified in the
+	// `waitIRq` parameter define what bits constitute a completed command.
+	// When they are set in the ComIrqReg register, then the command is
+	// considered complete. If the command is not indicated as complete in
+	// ~36ms, then consider the command as timed out.
+	const uint32_t deadline = millis() + 36;
+	bool completed = false;
+
+	do {
 		byte 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.
+			completed = true;
 			break;
 		}
 		if (n & 0x01) {						// Timer interrupt - nothing received in 25ms
 			return STATUS_TIMEOUT;
 		}
+		yield();
 	}
-	// 35.7ms and nothing happend. Communication with the MFRC522 might be down.
-	if (i == 0) {
+	while (static_cast<uint32_t> (millis()) < deadline);
+
+	// 36ms and nothing happened. Communication with the MFRC522 might be down.
+	if (!completed) {
 		return STATUS_TIMEOUT;
 	}