Move strings to PROGMEM string tables

This frees up almost 1KB of dynamic memory.

MFRC522.cpp

@@ -6,6 +6,7 @@
 
 #include <Arduino.h>
 #include <MFRC522.h>
+#include <avr/pgmspace.h>
 
 /////////////////////////////////////////////////////////////////////////////////////
 // Functions for setting up the Arduino
@@ -1072,20 +1073,11 @@ byte MFRC522::PCD_MIFARE_Transceive(	byte *sendData,		///< Pointer to the data t
  */
 const char *MFRC522::GetStatusCodeName(byte code	///< One of the StatusCode enums.
 										) {
-	switch (code) {
+	if (code == 0 || code > STATUS_MIFARE_NACK) {
-		case STATUS_OK:				return "Success."; break;
-		case STATUS_ERROR:			return "Error in communication."; break;
-		case STATUS_COLLISION:		return "Collission detected."; break;
-		case STATUS_TIMEOUT:		return "Timeout in communication."; break;
-		case STATUS_NO_ROOM:		return "A buffer is not big enough."; break;
-		case STATUS_INTERNAL_ERROR:	return "Internal error in the code. Should not happen."; break;
-		case STATUS_INVALID:		return "Invalid argument."; break;
-		case STATUS_CRC_WRONG:		return "The CRC_A does not match."; break;
-		case STATUS_MIFARE_NACK:	return "A MIFARE PICC responded with NAK."; break;
-		default:
 		return "Unknown error";
-			break;
 	}
+	strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_StatusCodeName[code - 1])));
+	return stringBuffer;
 } // End GetStatusCodeName()
 
 /**
@@ -1127,19 +1119,12 @@ byte MFRC522::PICC_GetType(byte sak		///< The SAK byte returned from PICC_Select
  */
 const char *MFRC522::PICC_GetTypeName(byte piccType	///< One of the PICC_Type enums.
 										) {
-	switch (piccType) {
+	if (piccType == PICC_TYPE_UNKNOWN) {
-		case PICC_TYPE_ISO_14443_4:		return "PICC compliant with ISO/IEC 14443-4";		break;
+		strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_Error[ERR_PICC_TYPE_NOT_COMPLETE])));
-		case PICC_TYPE_ISO_18092:		return "PICC compliant with ISO/IEC 18092 (NFC)";	break;
+	} else {
-		case PICC_TYPE_MIFARE_MINI:		return "MIFARE Mini, 320 bytes";					break;
+		strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_PICC_TypeName[piccType])));
-		case PICC_TYPE_MIFARE_1K:		return "MIFARE 1KB";								break;
-		case PICC_TYPE_MIFARE_4K:		return "MIFARE 4KB";								break;
-		case PICC_TYPE_MIFARE_UL:		return "MIFARE Ultralight or Ultralight C";			break;
-		case PICC_TYPE_MIFARE_PLUS:		return "MIFARE Plus";								break;
-		case PICC_TYPE_TNP3XXX:			return "MIFARE TNP3XXX";							break;
-		case PICC_TYPE_NOT_COMPLETE:	return "SAK indicates UID is not complete.";		break;
-		case PICC_TYPE_UNKNOWN:
-		default:						return "Unknown type";								break;
 	}
+	return stringBuffer;
 } // End PICC_GetTypeName()
 
 /**
@@ -1184,7 +1169,8 @@ void MFRC522::PICC_DumpToSerial(Uid *uid	///< Pointer to Uid struct returned fro
 		case PICC_TYPE_ISO_18092:
 		case PICC_TYPE_MIFARE_PLUS:
 		case PICC_TYPE_TNP3XXX:
-			Serial.println("Dumping memory contents not implemented for that PICC type.");
+			strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_Error[ERR_PICC_TYPE_TNP3XXX])));
+			Serial.println(stringBuffer);
 			break;
 			
 		case PICC_TYPE_UNKNOWN:
@@ -1458,7 +1444,8 @@ bool MFRC522::MIFARE_OpenUidBackdoor(bool logErrors) {
     byte status = PCD_TransceiveData(&cmd, (byte)1, response, &received, &validBits, (byte)0, false); // 40
     if( status != STATUS_OK ) {
         if( logErrors ) {
-            Serial.println("Card did not respond to 0x40 after HALT command. Are you sure it is a UID changeable one?");
+            strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_Error[ERR_NO_RESPONSE_AFTER_HALT])));
+            Serial.println(stringBuffer);
             Serial.print("Error name: ");
             Serial.println(GetStatusCodeName(status));
         }
@@ -1466,7 +1453,8 @@ bool MFRC522::MIFARE_OpenUidBackdoor(bool logErrors) {
     }
     if ( received != 1 || response[0] != 0x0A ) {
         if ( logErrors ) {
-            Serial.print("Got bad response on backdoor 0x40 command: ");
+            strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_Error[ERR_COMMAND_0x40_RESPONSE])));
+            Serial.print(stringBuffer);
             Serial.print(response[0], HEX);
             Serial.print(" (");
             Serial.print(validBits);
@@ -1480,7 +1468,8 @@ bool MFRC522::MIFARE_OpenUidBackdoor(bool logErrors) {
     status = PCD_TransceiveData(&cmd, (byte)1, response, &received, &validBits, (byte)0, false); // 43
     if( status != STATUS_OK ) {
         if( logErrors ) {
-            Serial.println("Error in communication at command 0x43, after successfully executing 0x40");
+            strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_Error[ERR_COMMAND_0x43_COMM])));
+            Serial.println(stringBuffer);
             Serial.print("Error name: ");
             Serial.println(GetStatusCodeName(status));
         }
@@ -1488,7 +1477,8 @@ bool MFRC522::MIFARE_OpenUidBackdoor(bool logErrors) {
     }
     if ( received != 1 || response[0] != 0x0A ) {
         if ( logErrors ) {
-            Serial.print("Got bad response on backdoor 0x43 command: ");
+            strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_Error[ERR_COMMAND_0x43_RESPONSE])));
+            Serial.print(stringBuffer);
             Serial.print(response[0], HEX);
             Serial.print(" (");
             Serial.print(validBits);
@@ -1514,7 +1504,8 @@ bool MFRC522::MIFARE_SetUid(byte* newUid, byte uidSize, bool logErrors) {
     // UID + BCC byte can not be larger than 16 together
     if ( !newUid || !uidSize || uidSize > 15) {
         if ( logErrors ) {
-            Serial.println("New UID buffer empty, size 0, or size > 15 given");
+            strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_Error[ERR_WRONG_UID])));
+            Serial.println(stringBuffer);
         }
         return false;
     }
@@ -1533,7 +1524,8 @@ bool MFRC522::MIFARE_SetUid(byte* newUid, byte uidSize, bool logErrors) {
 //            PICC_WakeupA(atqa_answer, &atqa_size);
             
             if ( !PICC_IsNewCardPresent() || !PICC_ReadCardSerial() ) {
-                Serial.println("No card was previously selected, and none are available. Failed to set UID.");
+                strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_Error[ERR_NO_CARD])));
+                Serial.println(stringBuffer);
                 return false;
             }
             
@@ -1541,7 +1533,8 @@ bool MFRC522::MIFARE_SetUid(byte* newUid, byte uidSize, bool logErrors) {
             if ( status != STATUS_OK ) {
                 // We tried, time to give up
                 if ( logErrors ) {
-                    Serial.println("Failed to authenticate to card for reading, could not set UID: ");
+                    strcpy_P(stringBuffer, (char*)pgm_read_word(&(_MFRC522_str_Error[ERR_AUTH_KEY_A])));
+                    Serial.println(stringBuffer);
                     Serial.println(GetStatusCodeName(status));
                 }
                 return false;

MFRC522.h

@@ -78,6 +78,88 @@
 #include <Arduino.h>
 #include <SPI.h>
 
+/////////////////////////////////////////////////////////////////////////////////////
+// String tables to be stored in program memory
+/////////////////////////////////////////////////////////////////////////////////////
+
+const char _MFRC522_str_STATUS_OK[] PROGMEM = "Success.";
+const char _MFRC522_str_STATUS_ERROR[] PROGMEM = "Error in communication.";
+const char _MFRC522_str_STATUS_COLLISION[] PROGMEM = "Collission detected.";
+const char _MFRC522_str_STATUS_TIMEOUT[] PROGMEM = "Timeout in communication.";
+const char _MFRC522_str_STATUS_NO_ROOM[] PROGMEM = "A buffer is not big enough.";
+const char _MFRC522_str_STATUS_INTERNAL_ERROR[] PROGMEM = "Internal error in the code. Should not happen.";
+const char _MFRC522_str_STATUS_INVALID[] PROGMEM = "Invalid argument.";
+const char _MFRC522_str_STATUS_CRC_WRONG[] PROGMEM = "The CRC_A does not match.";
+const char _MFRC522_str_STATUS_MIFARE_NACK[] PROGMEM = "A MIFARE PICC responded with NAK.";
+
+const char* const _MFRC522_str_StatusCodeName[] PROGMEM {
+	_MFRC522_str_STATUS_OK,
+	_MFRC522_str_STATUS_ERROR,
+	_MFRC522_str_STATUS_COLLISION,
+	_MFRC522_str_STATUS_TIMEOUT,
+	_MFRC522_str_STATUS_NO_ROOM,
+	_MFRC522_str_STATUS_INTERNAL_ERROR,
+	_MFRC522_str_STATUS_INVALID,
+	_MFRC522_str_STATUS_CRC_WRONG,
+	_MFRC522_str_STATUS_MIFARE_NACK
+};
+
+const char _MFRC522_str_PICC_TYPE_UNKNOWN[] PROGMEM = "Unknown type";
+const char _MFRC522_str_PICC_TYPE_ISO_14443_4[] PROGMEM = "PICC compliant with ISO/IEC 14443-4";
+const char _MFRC522_str_PICC_TYPE_ISO_18092[] PROGMEM = "PICC compliant with ISO/IEC 18092 (NFC)";
+const char _MFRC522_str_PICC_TYPE_MIFARE_MINI[] PROGMEM = "MIFARE Mini, 320 bytes";
+const char _MFRC522_str_PICC_TYPE_MIFARE_1K[] PROGMEM = "MIFARE 1KB";
+const char _MFRC522_str_PICC_TYPE_MIFARE_4K[] PROGMEM = "MIFARE 4KB";
+const char _MFRC522_str_PICC_TYPE_MIFARE_UL[] PROGMEM = "MIFARE Ultralight or Ultralight C";
+const char _MFRC522_str_PICC_TYPE_MIFARE_PLUS[] PROGMEM = "MIFARE Plus";
+const char _MFRC522_str_PICC_TYPE_TNP3XXX[] PROGMEM = "MIFARE TNP3XXX";
+
+const char* const _MFRC522_str_PICC_TypeName[] PROGMEM {
+	_MFRC522_str_PICC_TYPE_UNKNOWN,
+	_MFRC522_str_PICC_TYPE_ISO_14443_4,
+	_MFRC522_str_PICC_TYPE_ISO_18092,
+	_MFRC522_str_PICC_TYPE_MIFARE_MINI,
+	_MFRC522_str_PICC_TYPE_MIFARE_1K,
+	_MFRC522_str_PICC_TYPE_MIFARE_4K,
+	_MFRC522_str_PICC_TYPE_MIFARE_UL,
+	_MFRC522_str_PICC_TYPE_MIFARE_PLUS,
+	_MFRC522_str_PICC_TYPE_TNP3XXX
+};
+
+const char _MFRC522_str_ERR_PICC_TYPE_NOT_COMPLETE[] PROGMEM = "SAK indicates UID is not complete.";
+const char _MFRC522_str_ERR_PICC_TYPE_TNP3XXX[] PROGMEM = "Dumping memory contents not implemented for that PICC type.";
+const char _MFRC522_str_ERR_NO_RESPONSE_AFTER_HALT[] PROGMEM = "Card did not respond to 0x40 after HALT command. Are you sure it is a UID changeable one?";
+const char _MFRC522_str_ERR_COMMAND_0x40_RESPONSE[] PROGMEM = "Got bad response on backdoor 0x40 command: ";
+const char _MFRC522_str_ERR_COMMAND_0x43_COMM[] PROGMEM = "Error in communication at command 0x43, after successfully executing 0x40";
+const char _MFRC522_str_ERR_COMMAND_0x43_RESPONSE[] PROGMEM = "Got bad response on backdoor 0x43 command: ";
+const char _MFRC522_str_ERR_WRONG_UID[] PROGMEM = "New UID buffer empty, size 0, or size > 15 given";
+const char _MFRC522_str_ERR_NO_CARD[] PROGMEM = "No card was previously selected, and none are available. Failed to set UID.";
+const char _MFRC522_str_ERR_AUTH_KEY_A[] PROGMEM = "Failed to authenticate to card for reading, could not set UID: ";
+
+enum _MFRC522_str_Error {
+	ERR_PICC_TYPE_NOT_COMPLETE,
+	ERR_PICC_TYPE_TNP3XXX,
+	ERR_NO_RESPONSE_AFTER_HALT,
+	ERR_COMMAND_0x40_RESPONSE,
+	ERR_COMMAND_0x43_COMM,
+	ERR_COMMAND_0x43_RESPONSE,
+	ERR_WRONG_UID,
+	ERR_NO_CARD,
+	ERR_AUTH_KEY_A
+};
+
+const char* const _MFRC522_str_Error[] PROGMEM {
+	_MFRC522_str_ERR_PICC_TYPE_NOT_COMPLETE,
+	_MFRC522_str_ERR_PICC_TYPE_TNP3XXX,
+	_MFRC522_str_ERR_NO_RESPONSE_AFTER_HALT,
+	_MFRC522_str_ERR_COMMAND_0x40_RESPONSE,
+	_MFRC522_str_ERR_COMMAND_0x43_COMM,
+	_MFRC522_str_ERR_COMMAND_0x43_RESPONSE,
+	_MFRC522_str_ERR_WRONG_UID,
+	_MFRC522_str_ERR_NO_CARD,
+	_MFRC522_str_ERR_AUTH_KEY_A
+};
+
 class MFRC522 {
 public:
 	// MFRC522 registers. Described in chapter 9 of the datasheet.
@@ -218,7 +300,7 @@ public:
 		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.
+	// PICC types we can detect. Remember to update string tables and 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 
@@ -232,7 +314,7 @@ public:
 		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.
+	// Return codes from the functions in this class. Remember to update string tables and GetStatusCodeName() if you add more.
 	enum StatusCode {
 		STATUS_OK				= 1,	// Success
 		STATUS_ERROR			= 2,	// Error in communication
@@ -344,6 +426,8 @@ private:
 	byte _chipSelectPin;		// Arduino pin connected to MFRC522's SPI slave select input (Pin 24, NSS, active low)
 	byte _resetPowerDownPin;	// Arduino pin connected to MFRC522's reset and power down input (Pin 6, NRSTPD, active low)
 	byte MIFARE_TwoStepHelper(byte command, byte blockAddr, long data);
+
+	char stringBuffer[100];
 };
 
 #endif