diff --git a/src/utility/Sd2Card.cpp b/src/utility/Sd2Card.cpp
index 7cfbe73..dd07c0c 100644
--- a/src/utility/Sd2Card.cpp
+++ b/src/utility/Sd2Card.cpp
@@ -331,6 +331,24 @@ uint8_t Sd2Card::init(uint8_t sckRateID, uint8_t chipSelectPin) {
       goto fail;
     }
   }
+
+  uint8_t status_ext;
+  status_ = cardCommand(CMD13, 0);
+  status_ext = spiRec();
+  if ( status_ ) {
+    error(SD_CARD_ERROR_SEND_STATUS);
+    goto fail;
+  } else {
+    if (status_ext) {
+      if ( status_ext | 0X01 ) {
+        error(SD_CARD_ERROR_LOCKED);
+      } else {
+        error(SD_CARD_ERROR_SEND_STATUS);
+      }
+      goto fail;
+    }
+  }
+
   // if SD2 read OCR register to check for SDHC card
   if (type() == SD_CARD_TYPE_SD2) {
     if (cardCommand(CMD58, 0)) {
@@ -763,6 +781,74 @@ uint8_t Sd2Card::writeStop(void) {
   return false;
 }
 //------------------------------------------------------------------------------
+/** lock or unlock SD card by password
+ *
+ * \param[in] pwd si the pointer to password buffer
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ * 
+ */
+uint8_t Sd2Card::lockUnlockCard(uint8_t flags, int pass_len, uint8_t* pwd) {
+
+
+  // select card
+  chipSelectLow();
+
+  // set block length
+  if ( cardCommand(CMD16, 18) ) {
+    error(SD_CARD_ERROR_CMD16);
+    goto fail;
+  }
+
+
+  // send the command
+  if (cardCommand(CMD42, 0)) {
+    error(SD_CARD_ERROR_CMD42);
+    goto fail;
+  }
+  
+  spiSend( 0xFE ); // Start Token
+  spiSend( flags ); // 4-zeros ERASE LOCK_UNLOCK CLR_PWD SET_PWD
+  spiSend( pass_len );     // password length
+  
+  // send password
+  for ( uint16_t i=0; i<pass_len; i++ ) {
+      spiSend( pwd[i] );
+  }
+
+  // wait for response
+  do {
+    status_ = spiRec();
+  } while ( status_ == 0xFF );
+
+  uint8_t st;
+  do {
+    st = spiRec();
+  } while ( st != 0xFF );
+
+  status_ = cardCommand(CMD13, 0);
+  uint8_t status_ext;
+  status_ext = spiRec();
+  if ( status_ ) { 
+    goto fail;
+    error(0x89);
+  } else {
+    if ( status_ext ) {
+      status_ = status_ext;
+      error(0x8A);
+      goto fail;
+    }
+  }
+
+  chipSelectHigh();
+  return true;
+
+fail:
+  chipSelectHigh();
+  return false;
+  
+}
+//------------------------------------------------------------------------------
 /** Check if the SD card is busy
 
   \return The value one, true, is returned when is busy and
diff --git a/src/utility/Sd2Card.h b/src/utility/Sd2Card.h
index 5d91ebf..25af992 100644
--- a/src/utility/Sd2Card.h
+++ b/src/utility/Sd2Card.h
@@ -160,6 +160,14 @@ uint8_t const SD_CARD_ERROR_WRITE_PROGRAMMING = 0X14;
 uint8_t const SD_CARD_ERROR_WRITE_TIMEOUT = 0X15;
 /** incorrect rate selected */
 uint8_t const SD_CARD_ERROR_SCK_RATE = 0X16;
+/** error reading status */
+uint8_t const SD_CARD_ERROR_SEND_STATUS = 0X17;
+/** card is locked */
+uint8_t const SD_CARD_ERROR_LOCKED = 0X18;
+/** error lock/unlock card */
+uint8_t const SD_CARD_ERROR_CMD42 = 0X19;
+/** error lock/unlock card */
+uint8_t const SD_CARD_ERROR_CMD16 = 0X1A;
 //------------------------------------------------------------------------------
 // card types
 /** Standard capacity V1 SD card */
@@ -241,6 +249,8 @@ class Sd2Card {
     uint8_t writeStart(uint32_t blockNumber, uint32_t eraseCount);
     uint8_t writeStop(void);
     uint8_t isBusy(void);
+    uint8_t cardCommand(uint8_t cmd, uint32_t arg);
+    uint8_t lockUnlockCard(uint8_t flags, int pass_len, uint8_t* pwd);
   private:
     uint32_t block_;
     uint8_t chipSelectPin_;
@@ -255,7 +265,6 @@ class Sd2Card {
       cardCommand(CMD55, 0);
       return cardCommand(cmd, arg);
     }
-    uint8_t cardCommand(uint8_t cmd, uint32_t arg);
     void error(uint8_t code) {
       errorCode_ = code;
     }
diff --git a/src/utility/Sd2PinMap.h b/src/utility/Sd2PinMap.h
index 12d8926..bd5cbe2 100644
--- a/src/utility/Sd2PinMap.h
+++ b/src/utility/Sd2PinMap.h
@@ -523,6 +523,8 @@ void fastDigitalWrite(uint8_t pin, uint8_t value) {
 
 #endif	// Arduino ARC
 
+#elif defined(ESP32)
+// default SPI ports
 #else
 #error Architecture or board not supported.
 #endif
diff --git a/src/utility/SdInfo.h b/src/utility/SdInfo.h
index 6a0e087..f6872e9 100644
--- a/src/utility/SdInfo.h
+++ b/src/utility/SdInfo.h
@@ -42,6 +42,8 @@ uint8_t const CMD9 = 0X09;
 uint8_t const CMD10 = 0X0A;
 /** SEND_STATUS - read the card status register */
 uint8_t const CMD13 = 0X0D;
+/** SET_BLOCKLEN = Set Block length */
+uint8_t const CMD16 = 0X10;
 /** READ_BLOCK - read a single data block from the card */
 uint8_t const CMD17 = 0X11;
 /** WRITE_BLOCK - write a single data block to the card */
@@ -55,6 +57,8 @@ uint8_t const CMD32 = 0X20;
 uint8_t const CMD33 = 0X21;
 /** ERASE - erase all previously selected blocks */
 uint8_t const CMD38 = 0X26;
+/** SD_LOCK_UNLOCK - Sends lock/unlock command 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 */