Added FSK RSSI measurement

keywords.txt

@@ -65,6 +65,7 @@ setDataShaping KEYWORD2
 setOOK KEYWORD2
 setDataShapingOOK KEYWORD2
 setCRC KEYWORD2
+setRSSIConfig KEYWORD2
 
 #######################################
 # Constants (LITERAL1)
@@ -96,3 +97,5 @@ ERR_INVALID_SYNC_WORD LITERAL1
 ERR_INVALID_DATA_SHAPING LITERAL1
 ERR_INVALID_MODULATION LITERAL1
 ERR_MEMORY_ALLOCATION_FAILED LITERAL1
+ERR_INVALID_NUM_SAMPLES LITERAL1
+ERR_INVALID_RSSI_OFFSET LITERAL1

src/TypeDef.h

@@ -176,6 +176,16 @@
 */
 #define ERR_INVALID_MODULATION -26
 
+/*!
+ \brief The supplied number of RSSI samples is invalid.
+*/
+#define ERR_INVALID_NUM_SAMPLES -27
+
+/*!
+ \brief The supplied RSSI offset is invalid.
+*/
+#define ERR_INVALID_RSSI_OFFSET -28
+
 /*!
  \}
 */

src/modules/SX1272.cpp

@@ -342,22 +342,24 @@ int16_t SX1272::setDataShapingOOK(uint8_t sh) {
  return(state);
 }
 
-int8_t SX1272::getRSSI() {
- // check active modem
- if(getActiveModem() != SX127X_LORA) {
- return(0);
- }
+float SX1272::getRSSI() {
+ if(getActiveModem() == SX127X_LORA) {
+ // RSSI calculation uses different constant for low-frequency and high-frequency ports
+ float lastPacketRSSI = -139 + _mod->SPIgetRegValue(SX127X_REG_PKT_RSSI_VALUE);
+
+ // spread-spectrum modulation signal can be received below noise floor
+ // check last packet SNR and if it's less than 0, add it to reported RSSI to get the correct value
+ float lastPacketSNR = SX127x::getSNR();
+ if(lastPacketSNR < 0.0) {
+ lastPacketRSSI += lastPacketSNR;
+ }
 
- int8_t lastPacketRSSI = -139 + _mod->SPIgetRegValue(SX127X_REG_PKT_RSSI_VALUE);
+  return(lastPacketRSSI);
 
- // spread-spectrum modulation signal can be received below noise floor
- // check last packet SNR and if it's less than 0, add it to reported RSSI to get the correct value
- float lastPacketSNR = SX127x::getSNR();
- if(lastPacketSNR < 0.0) {
- lastPacketRSSI += lastPacketSNR;
+ } else {
+ // just read the value for FSK
+ return((float)_mod->SPIgetRegValue(SX127X_REG_RSSI_VALUE) / 2.0);
  }
-
- return(lastPacketRSSI);
 }
 
 int16_t SX1272::setCRC(bool enableCRC) {

src/modules/SX1272.h

@@ -235,11 +235,11 @@ class SX1272: public SX127x {
  int16_t setDataShapingOOK(uint8_t sh);
 
  /*!
- \brief Gets recorded signal strength indicator of the latest received packet.
+ \brief Gets recorded signal strength indicator of the latest received packet for LoRa modem, or current RSSI level for FSK modem.
 
- \returns Last packet recorded signal strength indicator (RSSI).
+ \returns Last packet RSSI for LoRa modem, or current RSSI level for FSK modem.
  */
- int8_t getRSSI();
+ float getRSSI();
 
  /*!
  \brief Enables/disables CRC check of received packets.

src/modules/SX1278.cpp

@@ -411,29 +411,31 @@ int16_t SX1278::setDataShapingOOK(uint8_t sh) {
  return(state);
 }
 
-int8_t SX1278::getRSSI() {
- // check active modem
- if(getActiveModem() != SX127X_LORA) {
- return(0);
- }
+float SX1278::getRSSI() {
+ if(getActiveModem() == SX127X_LORA) {
+ // for LoRa, get RSSI of the last packet
+ float lastPacketRSSI;
+
+ // RSSI calculation uses different constant for low-frequency and high-frequency ports
+ if(_freq < 868.0) {
+ lastPacketRSSI = -164 + _mod->SPIgetRegValue(SX127X_REG_PKT_RSSI_VALUE);
+ } else {
+ lastPacketRSSI = -157 + _mod->SPIgetRegValue(SX127X_REG_PKT_RSSI_VALUE);
+ }
 
- int8_t lastPacketRSSI;
+ // spread-spectrum modulation signal can be received below noise floor
+ // check last packet SNR and if it's less than 0, add it to reported RSSI to get the correct value
+ float lastPacketSNR = SX127x::getSNR();
+ if(lastPacketSNR < 0.0) {
+ lastPacketRSSI += lastPacketSNR;
+ }
 
- // RSSI calculation uses different constant for low-frequency and high-frequency ports
- if(_freq < 868.0) {
- lastPacketRSSI = -164 + _mod->SPIgetRegValue(SX127X_REG_PKT_RSSI_VALUE);
- } else {
- lastPacketRSSI = -157 + _mod->SPIgetRegValue(SX127X_REG_PKT_RSSI_VALUE);
- }
+ return(lastPacketRSSI);
 
- // spread-spectrum modulation signal can be received below noise floor
- // check last packet SNR and if it's less than 0, add it to reported RSSI to get the correct value
- float lastPacketSNR = SX127x::getSNR();
- if(lastPacketSNR < 0.0) {
- lastPacketRSSI += lastPacketSNR;
+ } else {
+ // just read the value for FSK
+ return((float)_mod->SPIgetRegValue(SX127X_REG_RSSI_VALUE) / 2.0);
  }
-
- return(lastPacketRSSI);
 }
 
 int16_t SX1278::setCRC(bool enableCRC) {

src/modules/SX1278.h

@@ -244,11 +244,11 @@ class SX1278: public SX127x {
  int16_t setDataShapingOOK(uint8_t sh);
 
  /*!
- \brief Gets recorded signal strength indicator of the latest received packet.
+ \brief Gets recorded signal strength indicator of the latest received packet for LoRa modem, or current RSSI level for FSK modem.
 
- \returns Last packet recorded signal strength indicator (RSSI).
+ \returns Last packet RSSI for LoRa modem, or current RSSI level for FSK modem.
  */
- int8_t getRSSI();
+ float getRSSI();
 
  /*!
  \brief Enables/disables CRC check of received packets.

src/modules/SX127x.cpp

@@ -468,7 +468,7 @@ int16_t SX127x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
 int16_t SX127x::readData(uint8_t* data, size_t len) {
  int16_t modem = getActiveModem();
  size_t length = len;
- 
+
  // put module to standby
  standby();
 
@@ -893,6 +893,33 @@ size_t SX127x::getPacketLength(bool update) {
  return(_packetLength);
 }
 
+int16_t SX127x::setRSSIConfig(uint8_t smoothingSamples, int8_t offset) {
+ // check active modem
+ if(getActiveModem() != SX127X_FSK_OOK) {
+ return(ERR_WRONG_MODEM);
+ }
+
+ // set mode to standby
+ int16_t state = standby();
+ if(state != ERR_NONE) {
+ return(state);
+ }
+
+ // check provided values
+ if(!(smoothingSamples <= 7)) {
+ return(ERR_INVALID_NUM_SAMPLES);
+ }
+
+ if(!((offset >= -16) && (offset <= 15))) {
+ return(ERR_INVALID_RSSI_OFFSET);
+ }
+
+ // set new register values
+ state = _mod->SPIsetRegValue(SX127X_REG_RSSI_CONFIG, offset, 7, 3);
+ state |= _mod->SPIsetRegValue(SX127X_REG_RSSI_CONFIG, smoothingSamples, 2, 0);
+ return(state);
+}
+
 int16_t SX127x::config() {
  // turn off frequency hopping
  int16_t state = _mod->SPIsetRegValue(SX127X_REG_HOP_PERIOD, SX127X_HOP_PERIOD_OFF);

src/modules/SX127x.h

@@ -842,6 +842,18 @@ class SX127x: public PhysicalLayer {
  */
  size_t getPacketLength(bool update = true);
 
+ /*!
+ \brief Sets RSSI measurement configuration in FSK mode.
+
+ \param smoothingSamples Number of samples taken to avergae the RSSI result.
+ numSamples = 2 ^ (1 + smoothingSamples), allowed values are in range 0 (2 samples) - 7 (256 samples)
+
+ \param offset Signed RSSI offset that will be automatically compensated. 1 dB per LSB, defaults to 0, allowed values are in range -16 dB to +15 dB.
+
+ \returns \ref status_codes
+ */
+ int16_t setRSSIConfig(uint8_t smoothingSamples, int8_t offset = 0);
+
  #ifdef RADIOLIB_DEBUG
  void regDump();
  #endif