diff --git a/VERSION b/VERSION
index e9307ca..7ec1d6d 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.0.2
+2.1.0
diff --git a/libloragw/inc/loragw_mcu.h b/libloragw/inc/loragw_mcu.h
index b238894..0d0588f 100644
--- a/libloragw/inc/loragw_mcu.h
+++ b/libloragw/inc/loragw_mcu.h
@@ -28,7 +28,7 @@ License: Revised BSD License, see LICENSE.TXT file include in the project
 /* -------------------------------------------------------------------------- */
 /* --- PUBLIC CONSTANTS ----------------------------------------------------- */
 
-static const char mcu_version_string[] = "00.02.06";
+static const char mcu_version_string[] = "01.00.00";
 
 #define MAX_SIZE_COMMAND ( 4200 )
 #define MAX_SPI_COMMAND ( MAX_SIZE_COMMAND - CMD_OFFSET__DATA - 1 )
@@ -45,18 +45,16 @@ typedef enum order_id_e
     ORDER_ID__REQ_BOOTLOADER_MODE = 0x02,
     ORDER_ID__REQ_RESET           = 0x03,
     ORDER_ID__REQ_WRITE_GPIO      = 0x04,
-    ORDER_ID__REQ_SPI             = 0x05, /* deprecated */
-    ORDER_ID__REQ_MULTIPLE_SPI    = 0x06,
+    ORDER_ID__REQ_MULTIPLE_SPI    = 0x05,
 
     ORDER_ID__ACK_PING            = 0x40,
     ORDER_ID__ACK_GET_STATUS      = 0x41,
     ORDER_ID__ACK_BOOTLOADER_MODE = 0x42,
     ORDER_ID__ACK_RESET           = 0x43,
     ORDER_ID__ACK_WRITE_GPIO      = 0x44,
-    ORDER_ID__ACK_SPI             = 0x45, /* deprecated */
-    ORDER_ID__ACK_MULTIPLE_SPI    = 0x46,
+    ORDER_ID__ACK_MULTIPLE_SPI    = 0x45,
 
-    ORDER_ID__UNKNOW_CMD = 0xFF
+    ORDER_ID__CMD_ERROR = 0xFF
 } order_id_t;
 
 typedef enum
diff --git a/libloragw/src/loragw_mcu.c b/libloragw/src/loragw_mcu.c
index 658e2a3..4644df8 100644
--- a/libloragw/src/loragw_mcu.c
+++ b/libloragw/src/loragw_mcu.c
@@ -146,8 +146,6 @@ const char * cmd_get_str(const uint8_t cmd) {
             return "REQ_RESET";
         case ORDER_ID__REQ_WRITE_GPIO:
             return "REQ_WRITE_GPIO";
-        case ORDER_ID__REQ_SPI:
-            return "REQ_SPI";
         case ORDER_ID__REQ_MULTIPLE_SPI:
             return "REQ_MULTIPLE_SPI";
         default:
@@ -197,6 +195,10 @@ int write_req(int fd, order_id_t cmd, const uint8_t * payload, uint16_t payload_
     int n;
     /* performances variables */
     struct timeval tm;
+    /* debug variables */
+#if DEBUG_MCU == 1
+    struct timeval write_tv;
+#endif
 
     /* Record function start time */
     _meas_time_start(&tm);
@@ -231,7 +233,10 @@ int write_req(int fd, order_id_t cmd, const uint8_t * payload, uint16_t payload_
         }
     }
 
-    DEBUG_PRINTF("\nINFO: write_req 0x%02X (%s) done, id:0x%02X\n", cmd, cmd_get_str(cmd), buf_w[0]);
+#if DEBUG_MCU == 1
+    gettimeofday(&write_tv, NULL);
+#endif
+    DEBUG_PRINTF("\nINFO: %ld.%ld: write_req 0x%02X (%s) done, id:0x%02X, size:%u\n", write_tv.tv_sec, write_tv.tv_usec, cmd, cmd_get_str(cmd), buf_w[0], payload_size);
 
 #if DEBUG_VERBOSE
     int i;
@@ -261,6 +266,10 @@ int read_ack(int fd, uint8_t * hdr, uint8_t * buf, size_t buf_size) {
     int nb_read = 0;
     /* performances variables */
     struct timeval tm;
+    /* debug variables */
+#if DEBUG_MCU == 1
+    struct timeval read_tv;
+#endif
 
     /* Record function start time */
     _meas_time_start(&tm);
@@ -274,7 +283,10 @@ int read_ack(int fd, uint8_t * hdr, uint8_t * buf, size_t buf_size) {
         perror("ERROR: Unable to read /dev/ttyACMx - ");
         return -1;
     } else {
-        DEBUG_PRINTF("INFO: read %d bytes for header from gateway\n", n);
+#if DEBUG_MCU == 1
+        gettimeofday(&read_tv, NULL);
+#endif
+        DEBUG_PRINTF("INFO: %ld.%ld: read %d bytes for header from gateway\n", read_tv.tv_sec, read_tv.tv_usec, n);
     }
 
     /* Compute time spent in this function */
@@ -317,7 +329,10 @@ int read_ack(int fd, uint8_t * hdr, uint8_t * buf, size_t buf_size) {
                 perror("ERROR: Unable to read /dev/ttyACMx - ");
                 return -1;
             } else {
-                DEBUG_PRINTF("INFO: read %d bytes from gateway\n", n);
+#if DEBUG_MCU == 1
+                gettimeofday(&read_tv, NULL);
+#endif
+                DEBUG_PRINTF("INFO: %ld.%ld: read %d bytes from gateway\n", read_tv.tv_sec, read_tv.tv_usec, n);
                 nb_read += n;
             }
         } while (nb_read < (int)size); /* we want to read only the expected payload, not more */
@@ -457,29 +472,6 @@ int decode_ack_gpio_access(const uint8_t * hdr, const uint8_t * payload, uint8_t
 
 /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
 
-int decode_ack_spi_access(const uint8_t * hdr, const uint8_t * payload) {
-    /* sanity checks */
-    if ((hdr == NULL) || (payload == NULL)) {
-        printf("ERROR: invalid parameter\n");
-        return -1;
-    }
-
-    if (cmd_get_type(hdr) != ORDER_ID__ACK_SPI) {
-        printf("ERROR: wrong ACK type for ACK_SPI (expected:0x%02X, got 0x%02X)\n", ORDER_ID__ACK_SPI, cmd_get_type(hdr));
-        return -1;
-    }
-
-#if DEBUG_VERBOSE
-    DEBUG_MSG   ("## ACK_SPI_ACCESS\n");
-    DEBUG_PRINTF("   id:           0x%02X\n", cmd_get_id(hdr));
-    DEBUG_PRINTF("   size:         %u\n", cmd_get_size(hdr));
-#endif
-
-    return 0;
-}
-
-/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
-
 int decode_ack_spi_bulk(const uint8_t * hdr, const uint8_t * payload) {
     uint8_t req_id, req_type, req_status;
     uint16_t frame_size;
diff --git a/mcu_bin/rlz_000206_CoreCell_USB.bin b/mcu_bin/rlz_010000_CoreCell_USB.bin
similarity index 62%
rename from mcu_bin/rlz_000206_CoreCell_USB.bin
rename to mcu_bin/rlz_010000_CoreCell_USB.bin
index da4bd99..3179a80 100644
Binary files a/mcu_bin/rlz_000206_CoreCell_USB.bin and b/mcu_bin/rlz_010000_CoreCell_USB.bin differ
diff --git a/readme.md b/readme.md
index f1f5e59..ce5b052 100644
--- a/readme.md
+++ b/readme.md
@@ -191,6 +191,30 @@ found in the `libtools` directory.
 
 ## 7. Changelog
 
+### v2.1.0 ###
+
+> #### Updates
+
+This release only targets USB Corecell (no change for SPI connexion type).
+The USB-SPI bridge firmware, which runs on the STM32 MCU of the USB Corecell, has
+been updated for API clean-up and robustness improvements.
+
+> #### Changes
+
+* MCU: USB-SPI bridge firmware binary v1.0.0.
+	* Removed obsolete commands (ORDER_ID__REQ_SPI, ORDER_ID__ACK_SPI)
+	* Command index shifted after obsolete commands removal (ORDER_ID__REQ_MULTIPLE_SPI, ORDER_ID__ACK_MULTIPLE_SPI)
+	* Command parser sends ORDER_ID__UNKNOW_CMD in case of wrong command size.
+	* Code clean-up (typo fixed, comments added...)
+	* Implemented Error_Handler() function to reset the MCU in case of fatal error.
+	* Fixed a potential roll-over issue in read_write_spi() function.
+	* Increased delay tolerance for host feedback on USB transfers.
+* HAL: Command interface updated for MCU firmware v1.0.0.
+	* Removed obsolete commands from enum order_id_e
+	* Shifted commands enum index according to USB-SPI bridge update.
+	* Removed decode_ack_spi_access() unused function.
+* HAL: Added timing debug information under DEBUG_MCU.
+
 ### v2.0.2 ###
 
 > #### Updates