add CMD42 to lock or unlock card

src/SD.cpp

@@ -371,6 +371,18 @@
     root.close();
   }
 
+  // protect a card with a password or remove it
+  bool SDClass::lockCard(bool setLock, const char pwd) {
+	  return card.lockCard(setLock, pwd);
+  }
+
+  // !!CAUTION!! call this to completly erase a card,
+  // this will unlock a card but also delete the complete file system,
+  // reformatting will be required!
+  bool SDClass::forceEraseCard(){
+	  return card.forceEraseCard();
+  }
+
   // this little helper is used to traverse paths
   SdFile SDClass::getParentDir(const char *filepath, int *index) {
     // get parent directory

src/SD.h

@@ -64,7 +64,7 @@
       SdFile root;
 
       // my quick&dirty iterator, should be replaced
       SdFile getParentDir(const char *filepath, int *indx);
     public:
       // This needs to be called to set up the connection to the SD card
       // before other methods are used.
@@ -106,6 +106,12 @@
         return rmdir(filepath.c_str());
       }
 
+      // lock card with a password
+      bool lockCard(bool setLock, const char pwd);
+      // !!CAUTION!! this can be used as last resort if the password of a locked card is unknown,
+      // this will remove the files and filesystem, a reformatting of the card is neccessary after this
+      bool forceEraseCard();
+
     private:
 
       // This is used to determine the mode used to open a file

src/utility/Sd2Card.cpp

@@ -775,3 +775,84 @@
 
   return (b != 0XFF);
 }
+
+/** Locks a card with a password
+  \param[in] setLock true if the card should be locked, false if it should be unlocked
+  \param[in] pwd password to lock/unlock the card
+
+	\return true if the locking was successful
+*/
+bool Sd2Card::lockCard(bool setLock, const char *pwd){
+	if(!isBusy()){
+		int16_t i;
+		uint8_t pwd_len = sizeof(pwd);
+		bool locked = false;
+
+		if(cardCommand(CMD42, 0) != 0){
+			return false;
+		}
+
+		spiSend(DATA_START_BLOCK);
+		if(setLock) {
+			spiSend(SET_CARD_PWD & 0x07);
+		}
+		else{
+			spiSend(CLEAR_CARD_PWD & 0x07);
+		}
+
+		spiSend(pwd_len);
+		for(i=0; i<512; i++){
+			if(i<pwd_len){
+				spiSend(pwd[i]);
+			}
+			else{
+				spiSend(0xFF);
+			}
+		}
+
+		locked = getCardStatus();
+
+		spiSend(0xFF);
+		spiSend(0xFF);
+
+		i = 0xFFFF;
+		while(isBusy() && (--i));
+
+		return locked;
+	}
+}
+
+/** Completly erase a card
+	!! Use with caution !! this removes everything from a card, even the file system.
+	Use this to remove a lock with an unknown password from a card.
+
+	\return true if the erase was successful
+*/
+bool Sd2Card::forceEraseCard(void) {
+	// set block size to 512 bytes
+	cardCommand(CMD16, 1);
+
+	// enable 
+	if(cardCommand(CMD42, 0) != 0){
+		return false;
+	}
+
+	spiSend(DATA_START_BLOCK);
+	spiSend(FORCE_ERASE);
+
+	return true;
+}
+
+/** Check status of card lock
+
+	\return true if card is locked
+*/
+bool Sd2Card::getCardStatus(void) {
+	bool cardOK = true;
+
+	if(cardCommand(CMD13, 0) || spiRec()) {
+		cardOK = false;
+	}
+
+	return cardOK;
+}

src/utility/Sd2Card.h

@@ -241,6 +241,10 @@ class Sd2Card {
     uint8_t writeStart(uint32_t blockNumber, uint32_t eraseCount);
     uint8_t writeStop(void);
     uint8_t isBusy(void);
+    /** un-/lock card with given password  */
+    bool lockCard(bool setLock, const char *pwd);
+    bool forceEraseCard(void);
+    bool getCardStatus(void);
   private:
     uint32_t block_;
     uint8_t chipSelectPin_;

src/utility/SdInfo.h

@@ -55,6 +55,8 @@ uint8_t const CMD32 = 0X20;
 uint8_t const CMD33 = 0X21;
 /** ERASE - erase all previously selected blocks */
 uint8_t const CMD38 = 0X26;
+/** LOCK_CMD - lock card with password */
+uint8_t const CMD42 = 0x2A; 
 /** APP_CMD - escape for application specific command */
 uint8_t const CMD55 = 0X37;
 /** READ_OCR - read the OCR register of a card */
@@ -82,6 +84,14 @@ uint8_t const WRITE_MULTIPLE_TOKEN = 0XFC;
 uint8_t const DATA_RES_MASK = 0X1F;
 /** write data accepted token */
 uint8_t const DATA_RES_ACCEPTED = 0X05;
+/** mask for setting a card password*/
+uint8_t const SET_CARD_PWD = 0x01;
+/** mask for removing a card password*/
+uint8_t const CLEAR_CARD_PWD = 0x02;
+/** mask for locking or unlocking a card*/
+uint8_t const ACTIVATE_CARD_LOCK = 0x04;
+/** mask to erase the entire card*/
+uint8_t const FORCE_ERASE = 0x08;
 //------------------------------------------------------------------------------
 typedef struct CID {
   // byte 0