Merge pull request #44 from mmrein/dev-sx126x-bitsync

[SX126x] Add setSyncBits method

examples/SX126x/SX126x_FSK_Modem/SX126x_FSK_Modem.ino

@@ -73,6 +73,13 @@ void setup() {
     Serial.println(state);
     while (true);
   }
+   
+  // FSK modem on SX126x can handle the sync word setting in bits, not just
+  // whole bytes. The value used is left-justified.
+  // This makes same result as fsk.setSyncWord(syncWord, 8):
+  state = fsk.setSyncBits(syncWord, 64);
+  // This will use 0x012 as sync word (12 bits only):
+  state = fsk.setSyncBits(syncWord, 12);
 
   // FSK modem allows advanced CRC configuration
   // Default is CCIT CRC16 (2 bytes, initial 0x1D0F, polynomial 0x1021, inverted)

keywords.txt

@@ -106,6 +106,7 @@ setDio2Action	KEYWORD2
 setTCXO	KEYWORD2
 setDio2AsRfSwitch	KEYWORD2
 getTimeOnAir	KEYWORD2
+setSyncBits KEYWORD2
 
 # ESP8266
 join	KEYWORD2

src/modules/SX126x.cpp

@@ -721,6 +721,35 @@ int16_t SX126x::setSyncWord(uint8_t* syncWord, uint8_t len) {
   return(state);
 }
 
+int16_t SX126x::setSyncBits(uint8_t *syncWord, uint8_t bitsLen) { 
+  // check active modem
+  if(getPacketType() != SX126X_PACKET_TYPE_GFSK) {
+    return(ERR_WRONG_MODEM);
+  }
+
+  // check sync word Length
+  if(bitsLen > 0x40) {
+    return(ERR_INVALID_SYNC_WORD);
+  }
+
+  uint8_t bytesLen = bitsLen / 8;
+  if ((bitsLen % 8) != 0) {
+    bytesLen++;
+  }
+  
+  // write sync word
+  int16_t state = writeRegister(SX126X_REG_SYNC_WORD_0, syncWord, bytesLen);
+  if(state != ERR_NONE) {
+    return(state);
+  }
+
+  // update packet parameters
+  _syncWordLength = bitsLen;
+  state = setPacketParamsFSK(_preambleLengthFSK, _crcTypeFSK, _syncWordLength, _addrComp);
+
+  return(state);
+}
+
 int16_t SX126x::setNodeAddress(uint8_t nodeAddr) {
   // check active modem
   if(getPacketType() != SX126X_PACKET_TYPE_GFSK) {

src/modules/SX126x.h

@@ -604,6 +604,17 @@ class SX126x: public PhysicalLayer {
     */
     int16_t setSyncWord(uint8_t* syncWord, uint8_t len);
 
+    /*!
+      \brief Sets FSK sync word in the form of array of up to 8 bytes.
+
+      \param syncWord FSK sync word to be set. 
+
+      \param len FSK sync word length in bits. If less than 64 bits the LSB's of syncWord will be ignored.
+
+      \returns \ref status_codes
+    */
+    int16_t setSyncBits(uint8_t *syncWord, uint8_t bitsLen);
+
     /*!
       \brief Sets node address. Calling this method will also enable address filtering for node address only.