diff --git a/libraries/AP_HAL/utility/srxl.cpp b/libraries/AP_HAL/utility/srxl.cpp
index cbaf5af1e4..fe21d88a2a 100644
--- a/libraries/AP_HAL/utility/srxl.cpp
+++ b/libraries/AP_HAL/utility/srxl.cpp
@@ -23,6 +23,7 @@
 #include <stdio.h>
 #include <stdint.h>
 #include <string.h>
+#include <AP_Math/crc.h>
 #include "srxl.h"
 
 
@@ -69,31 +70,6 @@ static uint16_t crc_receiver = 0U;                  /* CRC extracted from srxl d
 static uint16_t max_channels;
 
 
-
-
-/**
- * This function calculates the 16bit crc as used throughout the srxl protocol variants
- *
- * This function is intended to be called whenever a new byte shall be added to the crc.
- * Simply provide the old crc and the new data byte and the function return the new crc value.
- *
- * To start a new crc calculation for a new srxl frame, provide parameter crc=0 and the first byte of the frame.
- *
- * @param[in]   crc - start value for crc
- * @param[in]   new_byte - byte that shall be included in crc calculation
- * @return      calculated crc
- */
-static uint16_t srxl_crc16 (uint16_t crc, uint8_t new_byte)
-{
-    uint8_t loop;
-    crc = crc ^ (uint16_t)new_byte << 8;
-    for(loop = 0; loop < 8; loop++) {
-		crc = (crc & 0x8000) ? (crc << 1) ^ 0x1021 : (crc << 1);
-	}
-    return crc;
-}
-
-
 /**
  * Get RC channel information as microsecond pulsewidth representation from srxl version 1 and 2
  *
@@ -297,7 +273,7 @@ int srxl_decode(uint64_t timestamp_us, uint8_t byte, uint8_t *num_values, uint16
     switch (decode_state) {
     case STATE_NEW:   /* buffer header byte and prepare for frame reception and decoding */
         buffer[0U]=byte;
-        crc_fmu = srxl_crc16(0U,byte);
+        crc_fmu = crc_xmodem_update(0U,byte);
         buflen = 1U;
         decode_state_next = STATE_COLLECT;
         break;
@@ -315,7 +291,7 @@ int srxl_decode(uint64_t timestamp_us, uint8_t byte, uint8_t *num_values, uint16
         buflen++;
         /* CRC not over last 2 frame bytes as these bytes inhabitate the crc */
         if (buflen <= (frame_len_full-2)) {
-           crc_fmu = srxl_crc16(crc_fmu,byte);
+           crc_fmu = crc_xmodem_update(crc_fmu,byte);
         }
         if(  buflen == frame_len_full ) {
             /* CRC check here */
diff --git a/libraries/AP_HAL/utility/sumd.cpp b/libraries/AP_HAL/utility/sumd.cpp
index 7b4b0af86e..816460f009 100644
--- a/libraries/AP_HAL/utility/sumd.cpp
+++ b/libraries/AP_HAL/utility/sumd.cpp
@@ -45,6 +45,7 @@
 
 #include <stdio.h>
 #include <stdint.h>
+#include <AP_Math/crc.h>
 #include "sumd.h"
 
 #define SUMD_MAX_CHANNELS	32
@@ -116,18 +117,6 @@ static uint8_t _rxlen;
 static ReceiverFcPacketHoTT _rxpacket;
 
 
-static uint16_t sumd_crc16(uint16_t crc, uint8_t value)
-{
-	int i;
-	crc ^= (uint16_t)value << 8;
-
-	for (i = 0; i < 8; i++) {
-		crc = (crc & 0x8000) ? (crc << 1) ^ 0x1021 : (crc << 1);
-	}
-
-	return crc;
-}
-
 static uint8_t sumd_crc8(uint8_t crc, uint8_t value)
 {
 	crc += value;
@@ -153,7 +142,7 @@ int sumd_decode(uint8_t byte, uint8_t *rssi, uint8_t *rx_count, uint16_t *channe
 			_crc16 = 0x0000;
 			_crc8 = 0x00;
 			_crcOK = false;
-			_crc16 = sumd_crc16(_crc16, byte);
+			_crc16 = crc_xmodem_update(_crc16, byte);
 			_crc8 = sumd_crc8(_crc8, byte);
 			_decode_state = SUMD_DECODE_STATE_GOT_HEADER;
 
@@ -176,7 +165,7 @@ int sumd_decode(uint8_t byte, uint8_t *rssi, uint8_t *rx_count, uint16_t *channe
 			}
 
 			if (_sumd) {
-				_crc16 = sumd_crc16(_crc16, byte);
+				_crc16 = crc_xmodem_update(_crc16, byte);
 
 			} else {
 				_crc8 = sumd_crc8(_crc8, byte);
@@ -199,7 +188,7 @@ int sumd_decode(uint8_t byte, uint8_t *rssi, uint8_t *rx_count, uint16_t *channe
 			_rxpacket.length = byte;
 
 			if (_sumd) {
-				_crc16 = sumd_crc16(_crc16, byte);
+				_crc16 = crc_xmodem_update(_crc16, byte);
 
 			} else {
 				_crc8 = sumd_crc8(_crc8, byte);
@@ -222,7 +211,7 @@ int sumd_decode(uint8_t byte, uint8_t *rssi, uint8_t *rx_count, uint16_t *channe
 		_rxpacket.sumd_data[_rxlen] = byte;
 
 		if (_sumd) {
-			_crc16 = sumd_crc16(_crc16, byte);
+			_crc16 = crc_xmodem_update(_crc16, byte);
 
 		} else {
 			_crc8 = sumd_crc8(_crc8, byte);