From 8f3a5c7430c815bf5371512c1e2a68f16464fedc Mon Sep 17 00:00:00 2001
From: jgromes <jan.gromes@gmail.com>
Date: Mon, 28 Oct 2024 18:52:07 +0000
Subject: [PATCH] [LR11x0] Use array as LR-FHSS sync word

---
 .../LR11x0_LR_FHSS_Modem.ino                  |  3 +-
 src/modules/LR11x0/LR11x0.cpp                 | 48 +++++++++++--------
 src/modules/LR11x0/LR11x0.h                   |  6 +--
 3 files changed, 32 insertions(+), 25 deletions(-)

diff --git a/examples/LR11x0/LR11x0_LR_FHSS_Modem/LR11x0_LR_FHSS_Modem.ino b/examples/LR11x0/LR11x0_LR_FHSS_Modem/LR11x0_LR_FHSS_Modem.ino
index a7de634d..f1c7c198 100644
--- a/examples/LR11x0/LR11x0_LR_FHSS_Modem/LR11x0_LR_FHSS_Modem.ino
+++ b/examples/LR11x0/LR11x0_LR_FHSS_Modem/LR11x0_LR_FHSS_Modem.ino
@@ -62,7 +62,8 @@ void setup() {
                                 3,                                  // header count
                                 0x13A);                             // hopping sequence seed
   state = radio.setOutputPower(10.0);
-  state = radio.setSyncWord(0x12345678);
+  uint8_t syncWord[] = {0x01, 0x23, 0x45, 0x67};
+  state = radio.setSyncWord(syncWord, 4);
   if (state != RADIOLIB_ERR_NONE) {
     Serial.print(F("Unable to set configuration, code "));
     Serial.println(state);
diff --git a/src/modules/LR11x0/LR11x0.cpp b/src/modules/LR11x0/LR11x0.cpp
index f87a7f88..cedf5b5b 100644
--- a/src/modules/LR11x0/LR11x0.cpp
+++ b/src/modules/LR11x0/LR11x0.cpp
@@ -110,7 +110,8 @@ int16_t LR11x0::beginLRFHSS(uint8_t bw, uint8_t cr, bool narrowGrid, float tcxoV
   state = setLrFhssConfig(bw, cr);
   RADIOLIB_ASSERT(state);
 
-  state = setSyncWord(0x12AD101B);
+  uint8_t syncWord[] = { 0x12, 0xAD, 0x10, 0x1B };
+  state = setSyncWord(syncWord, 4);
   RADIOLIB_ASSERT(state);
 
   state = setRegulatorLDO();
@@ -758,20 +759,16 @@ int16_t LR11x0::setCodingRate(uint8_t cr, bool longInterleave) {
   return(setModulationParamsLoRa(this->spreadingFactor, this->bandwidth, this->codingRate, this->ldrOptimize));
 }
 
-int16_t LR11x0::setSyncWord(uint32_t syncWord) {
+int16_t LR11x0::setSyncWord(uint8_t syncWord) {
   // check active modem
   uint8_t type = RADIOLIB_LR11X0_PACKET_TYPE_NONE;
   int16_t state = getPacketType(&type);
   RADIOLIB_ASSERT(state);
-  if(type == RADIOLIB_LR11X0_PACKET_TYPE_LORA) {
-    return(setLoRaSyncWord(syncWord & 0xFF));
-  
-  } else if(type == RADIOLIB_LR11X0_PACKET_TYPE_LR_FHSS) {
-    return(lrFhssSetSyncWord(syncWord));
- 
+  if(type != RADIOLIB_LR11X0_PACKET_TYPE_LORA) {
+    return(RADIOLIB_ERR_WRONG_MODEM);
   }
   
-  return(RADIOLIB_ERR_WRONG_MODEM);
+  return(setLoRaSyncWord(syncWord));
 }
 
 int16_t LR11x0::setBitRate(float br) {
@@ -885,27 +882,36 @@ int16_t LR11x0::setSyncWord(uint8_t* syncWord, size_t len) {
   uint8_t type = RADIOLIB_LR11X0_PACKET_TYPE_NONE;
   int16_t state = getPacketType(&type);
   RADIOLIB_ASSERT(state);
-  if(type == RADIOLIB_LR11X0_PACKET_TYPE_LORA) {
+  if(type == RADIOLIB_LR11X0_PACKET_TYPE_GFSK) {
+    // update sync word length
+    this->syncWordLength = len*8;
+    state = setPacketParamsGFSK(this->preambleLengthGFSK, this->preambleDetLength, this->syncWordLength, this->addrComp, this->packetType, RADIOLIB_LR11X0_MAX_PACKET_LENGTH, this->crcTypeGFSK, this->whitening);
+    RADIOLIB_ASSERT(state);
+
+    // sync word is passed most-significant byte first
+    uint8_t fullSyncWord[RADIOLIB_LR11X0_GFSK_SYNC_WORD_LEN] = { 0 };
+    memcpy(fullSyncWord, syncWord, len);
+    return(setGfskSyncWord(fullSyncWord));
+
+  } else if(type == RADIOLIB_LR11X0_PACKET_TYPE_LORA) {
     // with length set to 1 and LoRa modem active, assume it is the LoRa sync word
     if(len > 1) {
       return(RADIOLIB_ERR_INVALID_SYNC_WORD);
     }
     return(setSyncWord(syncWord[0]));
 
-  } else if(type != RADIOLIB_LR11X0_PACKET_TYPE_GFSK) {
-    return(RADIOLIB_ERR_WRONG_MODEM);
+  } else if(type == RADIOLIB_LR11X0_PACKET_TYPE_LR_FHSS) {
+    // with length set to 4 and LR-FHSS modem active, assume it is the LR-FHSS sync word
+    if(len != sizeof(uint32_t)) {
+      return(RADIOLIB_ERR_INVALID_SYNC_WORD);
+    }
+    uint32_t sync = 0;
+    memcpy(&sync, syncWord, sizeof(uint32_t));
+    return(lrFhssSetSyncWord(sync));
   
   }
 
-  // update sync word length
-  this->syncWordLength = len*8;
-  state = setPacketParamsGFSK(this->preambleLengthGFSK, this->preambleDetLength, this->syncWordLength, this->addrComp, this->packetType, RADIOLIB_LR11X0_MAX_PACKET_LENGTH, this->crcTypeGFSK, this->whitening);
-  RADIOLIB_ASSERT(state);
-
-  // sync word is passed most-significant byte first
-  uint8_t fullSyncWord[RADIOLIB_LR11X0_GFSK_SYNC_WORD_LEN] = { 0 };
-  memcpy(fullSyncWord, syncWord, len);
-  return(setGfskSyncWord(fullSyncWord));
+  return(RADIOLIB_ERR_WRONG_MODEM);
 }
 
 int16_t LR11x0::setSyncBits(uint8_t *syncWord, uint8_t bitsLen) {
diff --git a/src/modules/LR11x0/LR11x0.h b/src/modules/LR11x0/LR11x0.h
index 974e8e3b..9ee985d5 100644
--- a/src/modules/LR11x0/LR11x0.h
+++ b/src/modules/LR11x0/LR11x0.h
@@ -1176,11 +1176,11 @@ class LR11x0: public PhysicalLayer {
     int16_t setCodingRate(uint8_t cr, bool longInterleave = false);
 
     /*!
-      \brief Sets LoRa or LR-FHSS sync word.
-      \param syncWord LoRa or LR-FHSS sync word to be set. For LoRa, only 8 least significant bits will be used
+      \brief Sets LoRa sync word.
+      \param syncWord LoRa sync word to be set.
       \returns \ref status_codes
     */
-    int16_t setSyncWord(uint32_t syncWord);
+    int16_t setSyncWord(uint8_t syncWord);
 
     /*!
       \brief Sets GFSK bit rate. Allowed values range from 0.6 to 300.0 kbps.