diff --git a/BUILD.txt b/BUILD.txt
index 94c271c..5332f3f 100644
--- a/BUILD.txt
+++ b/BUILD.txt
@@ -282,8 +282,8 @@ scanning over all enabled modes, and you could have some detection delay. Enable
 #define SERIAL_REPEATER: enable a second serial port (USART2, pins PA2 and PA3) for Nextion
 LCD display.
 
-Pinout definitions for ZUMSpot Libre Kit (Carrier board):
-=========================================================
+Pinout definitions for ZUMSpot Libre Kit (Carrier board, RF7021SE + STM32F103 board):
+=====================================================================================
 - Main RF7021SE board:
 CE             PC14
 SLE            PB8
@@ -328,3 +328,39 @@ PIN_DEB        PB9 (debugging pin)
 
 * You could install a serie resistor (10 - 100 ohms) in each TxRxData and TxRxCLK lines, for
 reducing EMI.
+
+Pinout definitions for Arduino Due/Zero + RF7021SE:
+===================================================
+Use STM32duino + Arduino IDE for building the code 
+
+- Main RF7021SE board:
+CE            12
+SLE            6
+SREAD          5
+SDATA          4   // 2 in Arduino Zero Pro
+SCLK           3 
+DATA           7 (TxRxData)*
+DCLK           8 (TxRxCLK)*
+CLKOUT         2   // 4 in Arduino Zero Pro  (jumper wire in RF7021SE)
+PAC            9 (PTT LED)
+VCC            3.3 V
+GND            Ground
+
+- Serial ports:
+USB Arduino Programming Port (host communication)
+
+- Status LEDs:
+COS_LED       10
+PTT_LED        9
+P25_LED       17
+YSF_LED       16
+DMR_LED       15
+DSTAR_LED     14
+
+- Misc pins:
+PIN_LED       13
+PIN_DEB       11
+
+* You could install a serie resistor (10 - 100 ohms) in each TxRxData and TxRxCLK lines, for
+reducing EMI.
+
diff --git a/DMRDMORX.cpp b/DMRDMORX.cpp
index 8b6ec0a..c44293c 100644
--- a/DMRDMORX.cpp
+++ b/DMRDMORX.cpp
@@ -25,7 +25,7 @@
 #include "DMRSlotType.h"
 #include "Utils.h"
 
-const uint8_t MAX_SYNC_BYTES_ERRS   = 1U;
+const uint8_t MAX_SYNC_BYTES_ERRS   = 3U;
 
 const uint8_t MAX_SYNC_LOST_FRAMES  = 13U;
 
@@ -206,7 +206,7 @@ void CDMRDMORX::correlateSync()
   if (m_startPtr >= DMO_BUFFER_LENGTH_BITS)
     m_startPtr -= DMO_BUFFER_LENGTH_BITS;
 
-    m_endPtr = m_dataPtr + DMR_SLOT_TYPE_LENGTH_BITS / 2U + DMR_INFO_LENGTH_BITS / 2U;
+  m_endPtr = m_dataPtr + DMR_SLOT_TYPE_LENGTH_BITS / 2U + DMR_INFO_LENGTH_BITS / 2U;
   if (m_endPtr >= DMO_BUFFER_LENGTH_BITS)
     m_endPtr -= DMO_BUFFER_LENGTH_BITS;
 
@@ -234,17 +234,28 @@ void CDMRDMORX::bitsToBytes(uint16_t start, uint8_t count, uint8_t* buffer)
   for (uint8_t i = 0U; i < count; i++) {
 
   buffer[i]  = 0U;
-  buffer[i] |= ((m_buffer[start + 0U] & 0x01) << 7);
-  buffer[i] |= ((m_buffer[start + 1U] & 0x01) << 6);
-  buffer[i] |= ((m_buffer[start + 2U] & 0x01) << 5);
-  buffer[i] |= ((m_buffer[start + 3U] & 0x01) << 4);
-  buffer[i] |= ((m_buffer[start + 4U] & 0x01) << 3);
-  buffer[i] |= ((m_buffer[start + 5U] & 0x01) << 2);
-  buffer[i] |= ((m_buffer[start + 6U] & 0x01) << 1);
-  buffer[i] |= ((m_buffer[start + 7U] & 0x01) << 0);
-
-  start += 8U;
-
+  buffer[i] |= ((m_buffer[start++] & 0x01) << 7);
+  if (start >= DMO_BUFFER_LENGTH_BITS)
+    start -= DMO_BUFFER_LENGTH_BITS;
+  buffer[i] |= ((m_buffer[start++] & 0x01) << 6);
+  if (start >= DMO_BUFFER_LENGTH_BITS)
+    start -= DMO_BUFFER_LENGTH_BITS;
+  buffer[i] |= ((m_buffer[start++] & 0x01) << 5);
+  if (start >= DMO_BUFFER_LENGTH_BITS)
+    start -= DMO_BUFFER_LENGTH_BITS;
+  buffer[i] |= ((m_buffer[start++] & 0x01) << 4);
+  if (start >= DMO_BUFFER_LENGTH_BITS)
+    start -= DMO_BUFFER_LENGTH_BITS;
+  buffer[i] |= ((m_buffer[start++] & 0x01) << 3);
+  if (start >= DMO_BUFFER_LENGTH_BITS)
+    start -= DMO_BUFFER_LENGTH_BITS;
+  buffer[i] |= ((m_buffer[start++] & 0x01) << 2);
+  if (start >= DMO_BUFFER_LENGTH_BITS)
+    start -= DMO_BUFFER_LENGTH_BITS;
+  buffer[i] |= ((m_buffer[start++] & 0x01) << 1);
+  if (start >= DMO_BUFFER_LENGTH_BITS)
+    start -= DMO_BUFFER_LENGTH_BITS;
+  buffer[i] |= ((m_buffer[start++] & 0x01) << 0);
   if (start >= DMO_BUFFER_LENGTH_BITS)
     start -= DMO_BUFFER_LENGTH_BITS;
   }
diff --git a/SerialPort.cpp b/SerialPort.cpp
index 664af32..565edde 100644
--- a/SerialPort.cpp
+++ b/SerialPort.cpp
@@ -69,9 +69,9 @@ const uint8_t MMDVM_DEBUG4       = 0xF4U;
 const uint8_t MMDVM_DEBUG5       = 0xF5U;
 
 #if defined(ADF7021_N_VER)
-#define DESCRIPTION              "MMDVM_HS-ADF7021N 20170414 (D-Star/DMR/YSF/P25)"
+#define DESCRIPTION              "MMDVM_HS-ADF7021N 20170521 (D-Star/DMR/YSF/P25)"
 #else
-#define DESCRIPTION              "MMDVM_HS-ADF7021 20170414 (D-Star/DMR/YSF/P25)"
+#define DESCRIPTION              "MMDVM_HS-ADF7021 20170521 (D-Star/DMR/YSF/P25)"
 #endif
 
 #define concat(a, b, c) a " (Build: " b " " c ")"