Merge pull request #103 from naggie/sx126x_implicit_mode

[SX126x] implicit mode

keywords.txt

@@ -117,6 +117,8 @@ clearGdo2Action	KEYWORD2
 setTCXO	KEYWORD2
 setDio2AsRfSwitch	KEYWORD2
 getTimeOnAir	KEYWORD2
+implicitHeader	KEYWORD2
+explicitHeader	KEYWORD2
 setSyncBits	KEYWORD2
 setWhitening	KEYWORD2
 startReceiveDutyCycle	KEYWORD2

src/modules/SX126x/SX126x.cpp

@@ -21,6 +21,8 @@ int16_t SX126x::begin(float bw, uint8_t sf, uint8_t cr, uint8_t syncWord, float
   _crcType = SX126X_LORA_CRC_ON;
   _preambleLength = preambleLength;
   _tcxoDelay = 0;
+  _headerType = SX126X_LORA_HEADER_EXPLICIT;
+  _implicitLen = 0xFF;
 
   // reset the module and verify startup
   int16_t state = reset();
@@ -287,7 +289,6 @@ int16_t SX126x::receive(uint8_t* data, size_t len) {
     // calculate timeout (100 LoRa symbols, the default for SX127x series)
     float symbolLength = (float)(uint32_t(1) << _sf) / (float)_bwKhz;
     timeout = (uint32_t)(symbolLength * 100.0 * 1000.0);
-
   } else if(modem == SX126X_PACKET_TYPE_GFSK) {
     // calculate timeout (500 % of expected time-one-air)
     size_t maxLen = len;
@@ -449,7 +450,7 @@ int16_t SX126x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
   int16_t state = ERR_NONE;
   uint8_t modem = getPacketType();
   if(modem == SX126X_PACKET_TYPE_LORA) {
-    state = setPacketParams(_preambleLength, _crcType, len);
+    state = setPacketParams(_preambleLength, _crcType, len, _headerType);
   } else if(modem == SX126X_PACKET_TYPE_GFSK) {
     state = setPacketParamsFSK(_preambleLengthFSK, _crcTypeFSK, _syncWordLength, _addrComp, _whitening, _packetType, len);
   } else {
@@ -598,6 +599,14 @@ int16_t SX126x::startReceiveCommon() {
   // clear interrupt flags
   state = clearIrqStatus();
 
+  // set implicit mode and expected len if applicable
+  if(_headerType == SX126X_LORA_HEADER_IMPLICIT && getPacketType() == SX126X_PACKET_TYPE_LORA) {
+    state = setPacketParams(_preambleLength, _crcType, _implicitLen, _headerType);
+    if(state != ERR_NONE) {
+      return(state);
+    }
+  }
+
   return(state);
 }
 
@@ -741,7 +750,7 @@ int16_t SX126x::setPreambleLength(uint16_t preambleLength) {
   uint8_t modem = getPacketType();
   if(modem == SX126X_PACKET_TYPE_LORA) {
     _preambleLength = preambleLength;
-    return(setPacketParams(_preambleLength, _crcType));
+    return(setPacketParams(_preambleLength, _crcType, _implicitLen, _headerType));
   } else if(modem == SX126X_PACKET_TYPE_GFSK) {
     _preambleLengthFSK = preambleLength;
     return(setPacketParamsFSK(_preambleLengthFSK, _crcTypeFSK, _syncWordLength, _addrComp, _whitening, _packetType));
@@ -1046,7 +1055,7 @@ int16_t SX126x::setCRC(uint8_t len, uint16_t initial, uint16_t polynomial, bool
       _crcType = SX126X_LORA_CRC_OFF;
     }
 
-    return(setPacketParams(_preambleLength, _crcType));
+    return(setPacketParams(_preambleLength, _crcType, _implicitLen, _headerType));
   }
 
   return(ERR_UNKNOWN);
@@ -1150,7 +1159,7 @@ uint32_t SX126x::getTimeOnAir(size_t len) {
       sfDivisor = 4*(_sf - 2);
     }
     const int8_t bitsPerCrc = 16;
-    const int8_t N_symbol_header = 20;
+    const int8_t N_symbol_header = _headerType == SX126X_LORA_HEADER_EXPLICIT ? 20 : 0;
 
     // numerator of equation in section 6.1.4 of SX1268 datasheet v1.1 (might not actually be bitcount, but it has len * 8)
     int16_t bitCount = (int16_t) 8 * len + _crcType * bitsPerCrc - 4 * _sf  + sfCoeff2 + N_symbol_header;
@@ -1169,6 +1178,14 @@ uint32_t SX126x::getTimeOnAir(size_t len) {
   }
 }
 
+int16_t SX126x::implicitHeader(size_t len) {
+    return(setHeaderType(SX126X_LORA_HEADER_IMPLICIT, len));
+}
+
+int16_t SX126x::explicitHeader() {
+    return(setHeaderType(SX126X_LORA_HEADER_EXPLICIT));
+}
+
 int16_t SX126x::setTCXO(float voltage, uint32_t delay) {
   // set mode to standby
   standby();
@@ -1345,6 +1362,25 @@ int16_t SX126x::setPacketMode(uint8_t mode, uint8_t len) {
   return(state);
 }
 
+int16_t SX126x::setHeaderType(uint8_t headerType, size_t len) {
+  // check active modem
+  if(getPacketType() != SX126X_PACKET_TYPE_LORA) {
+    return(ERR_WRONG_MODEM);
+  }
+
+  // set requested packet mode
+  int16_t state = setPacketParams(_preambleLength, _crcType, len, headerType);
+  if(state != ERR_NONE) {
+    return(state);
+  }
+
+  // update cached value
+  _headerType = headerType;
+  _implicitLen = len;
+
+  return(state);
+}
+
 int16_t SX126x::setModulationParams(uint8_t sf, uint8_t bw, uint8_t cr, uint8_t ldro) {
   // calculate symbol length and enable low data rate optimization, if needed
   if(ldro == 0xFF) {

src/modules/SX126x/SX126x.h

@@ -789,6 +789,22 @@ class SX126x: public PhysicalLayer {
      \returns Expected time-on-air in microseconds.
    */
    uint32_t getTimeOnAir(size_t len);
+
+    /*!
+     \brief Set implicit header mode for future reception/transmission.
+
+     \returns \ref status_codes
+   */
+   int16_t implicitHeader(size_t len);
+
+    /*!
+     \brief Set explicit header mode for future reception/transmission.
+
+     \param len Payload length in bytes.
+
+     \returns \ref status_codes
+   */
+   int16_t explicitHeader();
 #ifndef RADIOLIB_GODMODE
   protected:
 #endif
@@ -810,7 +826,7 @@ class SX126x: public PhysicalLayer {
     int16_t setTxParams(uint8_t power, uint8_t rampTime = SX126X_PA_RAMP_200U);
     int16_t setModulationParams(uint8_t sf, uint8_t bw, uint8_t cr, uint8_t ldro = 0xFF);
     int16_t setModulationParamsFSK(uint32_t br, uint8_t pulseShape, uint8_t rxBw, uint32_t freqDev);
-    int16_t setPacketParams(uint16_t preambleLength, uint8_t crcType, uint8_t payloadLength = 0xFF, uint8_t headerType = SX126X_LORA_HEADER_EXPLICIT, uint8_t invertIQ = SX126X_LORA_IQ_STANDARD);
+    int16_t setPacketParams(uint16_t preambleLength, uint8_t crcType, uint8_t payloadLength, uint8_t headerType, uint8_t invertIQ = SX126X_LORA_IQ_STANDARD);
     int16_t setPacketParamsFSK(uint16_t preambleLength, uint8_t crcType, uint8_t syncWordLength, uint8_t addrComp, uint8_t whitening, uint8_t packetType = SX126X_GFSK_PACKET_VARIABLE, uint8_t payloadLength = 0xFF, uint8_t preambleDetectorLength = SX126X_GFSK_PREAMBLE_DETECT_16);
     int16_t setBufferBaseAddress(uint8_t txBaseAddress = 0x00, uint8_t rxBaseAddress = 0x00);
     uint8_t getStatus();
@@ -822,6 +838,7 @@ class SX126x: public PhysicalLayer {
     int16_t setFrequencyRaw(float freq);
     int16_t setOptimalHiPowerPaConfig(int8_t* inOutPower);
     int16_t setPacketMode(uint8_t mode, uint8_t len);
+    int16_t setHeaderType(uint8_t headerType, size_t len = 0xFF);
 
     // fixes to errata
     int16_t fixSensitivity();
@@ -834,7 +851,7 @@ class SX126x: public PhysicalLayer {
 #endif
     Module* _mod;
 
-    uint8_t _bw, _sf, _cr, _ldro, _crcType;
+    uint8_t _bw, _sf, _cr, _ldro, _crcType, _headerType;
     uint16_t _preambleLength;
     float _bwKhz;
 
@@ -847,6 +864,8 @@ class SX126x: public PhysicalLayer {
 
     uint32_t _tcxoDelay;
 
+    size_t _implicitLen;
+
     int16_t config(uint8_t modem);
 
     // common low-level SPI interface