diff --git a/libraries/AP_RCProtocol/AP_RCProtocol_ST24.cpp b/libraries/AP_RCProtocol/AP_RCProtocol_ST24.cpp
index 7abed65105..eec468e59f 100644
--- a/libraries/AP_RCProtocol/AP_RCProtocol_ST24.cpp
+++ b/libraries/AP_RCProtocol/AP_RCProtocol_ST24.cpp
@@ -77,73 +77,14 @@ uint8_t AP_RCProtocol_ST24::st24_crc8(uint8_t *ptr, uint8_t len)
 
 void AP_RCProtocol_ST24::process_pulse(uint32_t width_s0, uint32_t width_s1)
 {
-    // convert to bit widths, allowing for up to about 4usec error, assuming 115200 bps
-    uint16_t bits_s0 = ((width_s0+4)*(uint32_t)115200) / 1000000;
-    uint16_t bits_s1 = ((width_s1+4)*(uint32_t)115200) / 1000000;
-    uint8_t bit_ofs, byte_ofs;
-    uint16_t nbits;
-
-    if (bits_s0 == 0 || bits_s1 == 0) {
-        // invalid data
-        goto reset;
+    uint8_t b;
+    if (ss.process_pulse(width_s0, width_s1, b)) {
+        _process_byte(b);
     }
-
-    byte_ofs = st24_state.bit_ofs/10;
-    bit_ofs = st24_state.bit_ofs%10;
-    if (byte_ofs >= ST24_MAX_FRAMELEN) {
-        goto reset;
-    }
-    // pull in the high bits
-    nbits = bits_s0;
-    if (nbits+bit_ofs > 10) {
-        nbits = 10 - bit_ofs;
-    }
-    st24_state.bytes[byte_ofs] |= ((1U<<nbits)-1) << bit_ofs;
-    st24_state.bit_ofs += nbits;
-    bit_ofs += nbits;
-    if (bits_s0 - nbits > 10) {
-        // we have a full frame
-        uint8_t byte;
-        uint8_t i;
-        for (i=0; i <= byte_ofs; i++) {
-            // get raw data
-            uint16_t v = st24_state.bytes[i];
-
-            // check start bit
-            if ((v & 1) != 0) {
-                break;
-            }
-            // check stop bits
-            if ((v & 0x200) != 0x200) {
-                break;
-            }
-            byte = ((v>>1) & 0xFF);
-            process_byte(byte, 115200);
-        }
-        memset(&st24_state, 0, sizeof(st24_state));
-    }
-
-    byte_ofs = st24_state.bit_ofs/10;
-    bit_ofs = st24_state.bit_ofs%10;
-
-    if (bits_s1+bit_ofs > 10) {
-        // invalid data
-        goto reset;
-    }
-
-    // pull in the low bits
-    st24_state.bit_ofs += bits_s1;
-    return;
-reset:
-    memset(&st24_state, 0, sizeof(st24_state));
 }
 
-void AP_RCProtocol_ST24::process_byte(uint8_t byte, uint32_t baudrate)
+void AP_RCProtocol_ST24::_process_byte(uint8_t byte)
 {
-    if (baudrate != 115200) {
-        return;
-    }
-
     switch (_decode_state) {
     case ST24_DECODE_STATE_UNSYNCED:
         if (byte == ST24_STX1) {
@@ -282,3 +223,11 @@ void AP_RCProtocol_ST24::process_byte(uint8_t byte, uint32_t baudrate)
         break;
     }
 }
+
+void AP_RCProtocol_ST24::process_byte(uint8_t byte, uint32_t baudrate)
+{
+    if (baudrate != 115200) {
+        return;
+    }
+    _process_byte(byte);
+}
diff --git a/libraries/AP_RCProtocol/AP_RCProtocol_ST24.h b/libraries/AP_RCProtocol/AP_RCProtocol_ST24.h
index 96423908f1..1c0c937049 100644
--- a/libraries/AP_RCProtocol/AP_RCProtocol_ST24.h
+++ b/libraries/AP_RCProtocol/AP_RCProtocol_ST24.h
@@ -18,6 +18,7 @@
 #pragma once
 
 #include "AP_RCProtocol.h"
+#include "SoftSerial.h"
 
 #define ST24_DATA_LEN_MAX	64
 #define ST24_MAX_FRAMELEN   70
@@ -41,6 +42,7 @@ public:
     void process_pulse(uint32_t width_s0, uint32_t width_s1) override;
     void process_byte(uint8_t byte, uint32_t baudrate) override;
 private:
+    void _process_byte(uint8_t byte);
     static uint8_t st24_crc8(uint8_t *ptr, uint8_t len);
     enum ST24_PACKET_TYPE {
         ST24_PACKET_TYPE_CHANNELDATA12 = 0,
@@ -145,9 +147,5 @@ private:
 
     ReceiverFcPacket _rxpacket;
 
-    struct {
-        uint16_t bytes[70];
-        uint16_t bit_ofs;
-        bool packet_parsed;
-    } st24_state;
+    SoftSerial ss{115200, SoftSerial::SERIAL_CONFIG_8N1};
 };
diff --git a/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.cpp b/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.cpp
index 08d4c03b56..6856c74ef8 100644
--- a/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.cpp
+++ b/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.cpp
@@ -84,72 +84,14 @@ uint8_t AP_RCProtocol_SUMD::sumd_crc8(uint8_t crc, uint8_t value)
 
 void AP_RCProtocol_SUMD::process_pulse(uint32_t width_s0, uint32_t width_s1)
 {
-    // convert to bit widths, allowing for up to about 4usec error, assuming 115200 bps
-    uint16_t bits_s0 = ((width_s0+4)*(uint32_t)115200) / 1000000;
-    uint16_t bits_s1 = ((width_s1+4)*(uint32_t)115200) / 1000000;
-    uint8_t bit_ofs, byte_ofs;
-    uint16_t nbits;
-
-    if (bits_s0 == 0 || bits_s1 == 0) {
-        // invalid data
-        goto reset;
+    uint8_t b;
+    if (ss.process_pulse(width_s0, width_s1, b)) {
+        _process_byte(b);
     }
-
-    byte_ofs = sumd_state.bit_ofs/10;
-    bit_ofs = sumd_state.bit_ofs%10;
-    if (byte_ofs >= SUMD_FRAME_MAXLEN) {
-        goto reset;
-    }
-    // pull in the high bits
-    nbits = bits_s0;
-    if (nbits+bit_ofs > 10) {
-        nbits = 10 - bit_ofs;
-    }
-    sumd_state.bytes[byte_ofs] |= ((1U<<nbits)-1) << bit_ofs;
-    sumd_state.bit_ofs += nbits;
-    bit_ofs += nbits;
-    if (bits_s0 - nbits > 10) {
-        // we have a full frame
-        uint8_t byte;
-        uint8_t i;
-        for (i=0; i <= byte_ofs; i++) {
-            // get raw data
-            uint16_t v = sumd_state.bytes[i];
-
-            // check start bit
-            if ((v & 1) != 0) {
-                break;
-            }
-            // check stop bits
-            if ((v & 0x200) != 0x200) {
-                break;
-            }
-            byte = ((v>>1) & 0xFF);
-            process_byte(byte, 115200);
-        }
-        memset(&sumd_state, 0, sizeof(sumd_state));
-    }
-
-    byte_ofs = sumd_state.bit_ofs/10;
-    bit_ofs = sumd_state.bit_ofs%10;
-
-    if (bits_s1+bit_ofs > 10) {
-        // invalid data
-        goto reset;
-    }
-
-    // pull in the low bits
-    sumd_state.bit_ofs += bits_s1;
-    return;
-reset:
-    memset(&sumd_state, 0, sizeof(sumd_state));
 }
 
-void AP_RCProtocol_SUMD::process_byte(uint8_t byte, uint32_t baudrate)
+void AP_RCProtocol_SUMD::_process_byte(uint8_t byte)
 {
-    if (baudrate != 115200) {
-        return;
-    }
     switch (_decode_state) {
     case SUMD_DECODE_STATE_UNSYNCED:
 #ifdef SUMD_DEBUG
@@ -387,3 +329,12 @@ void AP_RCProtocol_SUMD::process_byte(uint8_t byte, uint32_t baudrate)
         break;
     }
 }
+
+void AP_RCProtocol_SUMD::process_byte(uint8_t byte, uint32_t baudrate)
+{
+    if (baudrate != 115200) {
+        return;
+    }
+    _process_byte(byte);
+}
+
diff --git a/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.h b/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.h
index 3eff2e5cdb..554751930b 100644
--- a/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.h
+++ b/libraries/AP_RCProtocol/AP_RCProtocol_SUMD.h
@@ -18,6 +18,8 @@
 #pragma once
 
 #include "AP_RCProtocol.h"
+#include "SoftSerial.h"
+
 #define SUMD_MAX_CHANNELS	32
 #define SUMD_FRAME_MAXLEN   40
 class AP_RCProtocol_SUMD : public AP_RCProtocol_Backend {
@@ -25,7 +27,9 @@ public:
     AP_RCProtocol_SUMD(AP_RCProtocol &_frontend) : AP_RCProtocol_Backend(_frontend) {}
     void process_pulse(uint32_t width_s0, uint32_t width_s1) override;
     void process_byte(uint8_t byte, uint32_t baudrate) override;
+
 private:
+    void _process_byte(uint8_t byte);
     static uint16_t sumd_crc16(uint16_t crc, uint8_t value);
     static uint8_t sumd_crc8(uint8_t crc, uint8_t value);
 
@@ -61,9 +65,6 @@ private:
     uint16_t 	_crc16  = 0x0000;
     bool 		_sumd	= true;
     bool		_crcOK	= false;
-    struct {
-        uint16_t bytes[40];
-        uint16_t bit_ofs;
-        bool packet_parsed;
-    } sumd_state;
+
+    SoftSerial ss{115200, SoftSerial::SERIAL_CONFIG_8N1};
 };