diff --git a/src/Makefile b/src/Makefile
index afa855db3..9829b3d7d 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -515,7 +515,7 @@ ifeq ($(PCB), X9D)
   OPT = 2
   CPPDEFS += -DPCBX9D -DCPUARM -DEEPROM_VARIANT=0 -DAUDIO -DPXX
   EXTRAINCDIRS += x9d CoOS/kernel CoOS/portable
-  EXTRAINCDIRS += x9d/STM32F2xx_StdPeriph_Lib_V1.1.0/Libraries/STM32F2xx_StdPeriph_Driver/inc x9d/STM32F2xx_StdPeriph_Lib_V1.1.0/Libraries/CMSIS/Device/ST/STM32F2xx/Include
+  EXTRAINCDIRS += x9d/STM32F2xx_StdPeriph_Lib_V1.1.0/Libraries/STM32F2xx_StdPeriph_Driver/inc x9d/STM32F2xx_StdPeriph_Lib_V1.1.0/Libraries/CMSIS/Device/ST/STM32F2xx/Include x9d/STM32F2xx_StdPeriph_Lib_V1.1.0/Libraries/CMSIS/include
   EXTRAINCDIRS += x9d/STM32_USB-Host-Device_Lib_V2.1.0/Libraries/STM32_USB_OTG_Driver/inc x9d/STM32_USB-Host-Device_Lib_V2.1.0/Libraries/STM32_USB_Device_Library/Core/inc 
   EXTRAINCDIRS += x9d/STM32_USB-Host-Device_Lib_V2.1.0/Libraries/STM32_USB_Device_Library/Class/msc/inc x9d/STM32_USB-Host-Device_Lib_V2.1.0/Libraries/STM32_USB_Device_Library/Class/hid/inc 
   BOARDSRC = x9d/board_x9d.cpp
diff --git a/src/pulses_arm.cpp b/src/pulses_arm.cpp
index c813b49fe..80757b3fa 100644
--- a/src/pulses_arm.cpp
+++ b/src/pulses_arm.cpp
@@ -188,7 +188,7 @@ void crc( uint8_t data )
 {
   //  uint8_t i ;
 
-  PcmCrc=(PcmCrc>>8)^(CRCTable[(PcmCrc^data) & 0xFF]);
+  PcmCrc=(PcmCrc<<8)^(CRCTable[((PcmCrc>>8)^data) & 0xFF]);
 }
 
 #if defined(PCBSKY9X)
@@ -341,9 +341,10 @@ void setupPulsesPXX()
   }
 
   /* CRC16 */
+  putPcmByte(0);
   chan = PcmCrc;
+  putPcmByte(chan>>8);
   putPcmByte(chan);
-  putPcmByte(chan >> 8);
 
   /* Sync */
   putPcmHead();
diff --git a/src/pulses_avr.cpp b/src/pulses_avr.cpp
index 0d8a2fa8d..fe840fc52 100644
--- a/src/pulses_avr.cpp
+++ b/src/pulses_avr.cpp
@@ -235,7 +235,7 @@ uint8_t pxxFlag = 0;
 
 void crc( uint8_t data )
 {
-    PcmCrc=(PcmCrc>>8)^pgm_read_word(&CRCTable[(PcmCrc^data) & 0xFF]);
+    PcmCrc=(PcmCrc<<8)^pgm_read_word(&CRCTable[((PcmCrc>>8)^data) & 0xFF]);
 }
 
 
@@ -331,9 +331,10 @@ void setupPulsesPXX()
         putPcmByte( ( ( chan >> 8 ) & 0x0F ) | ( chan_1 << 4) ) ;  // 4 bits each from 2 channels
         putPcmByte( chan_1 >> 4 ) ;  // High byte of channel
     }
+    putPcbByte(0);
     chan = PcmCrc ;                     // get the crc
-    putPcmByte( chan ) ;                        // Checksum lo
-    putPcmByte( chan >> 8 ) ; // Checksum hi
+    putPcmByte( chan>>8 ) ;                        // Checksum lo
+    putPcmByte( chan ) ; // Checksum hi
     putPcmHead( ) ;
     putPcmFlush() ;
     OCR1C += 40000 ;            // 20mS on