Merge pull request #57 from BarryPSmith/sx126x_txpower

Sx126x txpower

src/modules/SX1261.cpp

@@ -0,0 +1,50 @@
+#include "SX1261.h"
+
+SX1261::SX1261(Module* mod) 
+  : SX1262(mod) {
+
+}
+
+int16_t SX1261::setOutputPower(int8_t power) {  
+  // check allowed power range
+  if (!((power >= -17) && (power <= 14))) {
+    return(ERR_INVALID_OUTPUT_POWER);
+  }
+
+  // get current OCP configuration
+  uint8_t ocp = 0;
+  int16_t state = readRegister(SX126X_REG_OCP_CONFIGURATION, &ocp, 1);
+  if (state != ERR_NONE) {
+    return(state);
+  }
+
+  state = setOptimalLowPowerPaConfig(&power);
+  if (state != ERR_NONE) {
+    return(state);
+  }
+
+  // set output power
+  // TODO power ramp time configuration
+  state = SX126x::setTxParams(power);
+  if (state != ERR_NONE) {
+    return(state);
+  }
+
+  // restore OCP configuration
+  return writeRegister(SX126X_REG_OCP_CONFIGURATION, &ocp, 1);
+}
+
+int16_t SX1261::setOptimalLowPowerPaConfig(int8_t* inOutPower)
+{
+  int16_t state;
+  if (*inOutPower > 10) {
+    state = SX126x::setPaConfig(0x04, SX126X_PA_CONFIG_SX1261, 0x00);
+  }
+  else {
+    state = SX126x::setPaConfig(0x01, SX126X_PA_CONFIG_SX1261, 0x00);
+    // changing the PaConfig means output power is now scaled so we get 3 dB less than requested.
+    // see datasheet table 13-21 and comments in setOptimalHiPowerPaConfig.
+    *inOutPower -= 3;
+  }
+  return state;
+}

src/modules/SX1261.h

@@ -8,9 +8,29 @@
 
 //SX126X_CMD_SET_PA_CONFIG
 #define SX126X_PA_CONFIG_SX1261                       0x01
-#define SX126X_PA_CONFIG_SX1262                       0x00
 
 // TODO: implement SX1261 class
-using SX1261 = SX1262;
+class SX1261 : public SX1262 {
+  public:
+    /*!
+      \brief Default constructor.
+
+      \param mod Instance of Module that will be used to communicate with the radio.
+    */
+    SX1261(Module* mod);
+
+    /*!
+      \brief Sets output power. Allowed values are in range from -17 to 14 dBm.
+
+      \param power Output power to be set in dBm.
+
+      \returns \ref status_codes
+    */
+    int16_t setOutputPower(int8_t power);
+
+  private:
+    int16_t setOptimalLowPowerPaConfig(int8_t* inOutPower);
+};
+
 
 #endif

src/modules/SX1262.cpp

@@ -85,28 +85,32 @@ int16_t SX1262::setFrequency(float freq, bool calibrate) {
 
 int16_t SX1262::setOutputPower(int8_t power) {
   // check allowed power range
-  if(!((power >= -17) && (power <= 22))) {
+  if (!((power >= -17) && (power <= 22))) {
     return(ERR_INVALID_OUTPUT_POWER);
   }
 
   // get current OCP configuration
   uint8_t ocp = 0;
   int16_t state = readRegister(SX126X_REG_OCP_CONFIGURATION, &ocp, 1);
-  if(state != ERR_NONE) {
+  if (state != ERR_NONE) {
     return(state);
   }
 
-  // enable high power PA for output power higher than 14 dBm
-  if(power > 13) {
-    SX126x::setPaConfig(0x04, SX126X_PA_CONFIG_SX1262);
-  } else {
-    SX126x::setPaConfig(0x04, SX126X_PA_CONFIG_SX1261);
+  // this function sets the optimal PA settings 
+  // and adjusts power based on the PA settings chosen
+  // so that output power matches requested power.
+  state = SX126x::setOptimalHiPowerPaConfig(&power);
+  if (state != ERR_NONE) {
+    return(state);
   }
 
   // set output power
   // TODO power ramp time configuration
-  SX126x::setTxParams(power);
+  state = SX126x::setTxParams(power);
+  if (state != ERR_NONE) {
+    return(state);
+  }
 
   // restore OCP configuration
-  return(writeRegister(SX126X_REG_OCP_CONFIGURATION, &ocp, 1));
+  return writeRegister(SX126X_REG_OCP_CONFIGURATION, &ocp, 1);
 }

src/modules/SX1262.h

@@ -6,8 +6,6 @@
 #include "SX126x.h"
 
 //SX126X_CMD_SET_PA_CONFIG
-#define SX126X_PA_CONFIG_SX1261                       0x01
-#define SX126X_PA_CONFIG_SX1262                       0x00
 
 /*!
   \class SX1262

src/modules/SX1268.cpp

@@ -89,13 +89,19 @@ int16_t SX1268::setOutputPower(int8_t power) {
     return(state);
   }
 
-  // enable high power PA
-  SX126x::setPaConfig(0x04, SX126X_PA_CONFIG_SX1268);
+  // enable optimal PA - this changes the value of power.
+  state = SX126x::setOptimalHiPowerPaConfig(&power);
+  if (state != ERR_NONE) {
+    return(state);
+  }
 
   // set output power
   // TODO power ramp time configuration
-  SX126x::setTxParams(power);
+  state = SX126x::setTxParams(power);
+  if (state != ERR_NONE) {
+    return(state);
+  }
 
   // restore OCP configuration
-  return(writeRegister(SX126X_REG_OCP_CONFIGURATION, &ocp, 1));
+  return writeRegister(SX126X_REG_OCP_CONFIGURATION, &ocp, 1);
 }

src/modules/SX126x.cpp

@@ -1127,6 +1127,32 @@ int16_t SX126x::setTxParams(uint8_t power, uint8_t rampTime) {
   return(SPIwriteCommand(SX126X_CMD_SET_TX_PARAMS, data, 2));
 }
 
+// set PA config for optimal consumption as described in section 13-21 of the datasheet.
+int16_t SX126x::setOptimalHiPowerPaConfig(int8_t * inOutPower)
+{
+  // the final column of Table 13-21 suggests that the value passed in SetTxParams 
+  // is actually scaled depending on the parameters of setPaConfig.
+  // Testing confirms this is approximately right
+  int16_t state;
+  if (*inOutPower >= 21) {
+    state = SX126x::setPaConfig(0x04, SX126X_PA_CONFIG_SX1262_8, SX126X_PA_CONFIG_HP_MAX/*0x07*/);
+  }
+  else if (*inOutPower >= 18) {
+    state = SX126x::setPaConfig(0x03, SX126X_PA_CONFIG_SX1262_8, 0x05);
+    // datasheet instructs request 22 dBm for 20 dBm actual output power
+    *inOutPower += 2;
+  } else if (*inOutPower >= 15) {
+    state = SX126x::setPaConfig(0x02, SX126X_PA_CONFIG_SX1262_8, 0x03);
+    // datasheet instructs request 22 dBm for 17 dBm actual output power
+    *inOutPower += 5;
+  } else {
+    state = SX126x::setPaConfig(0x02, SX126X_PA_CONFIG_SX1262_8, 0x02);
+    // datasheet instructs request 22 dBm for 14 dBm actual output power.
+    *inOutPower += 8;
+  }
+  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.h

@@ -152,6 +152,7 @@
 //SX126X_CMD_SET_PA_CONFIG
 #define SX126X_PA_CONFIG_HP_MAX                       0x07
 #define SX126X_PA_CONFIG_PA_LUT                       0x01
+#define SX126X_PA_CONFIG_SX1262_8                     0x00
 
 //SX126X_CMD_SET_RX_TX_FALLBACK_MODE
 #define SX126X_RX_TX_FALLBACK_MODE_FS                 0x40        //  7     0     after Rx/Tx go to: FS mode
@@ -739,6 +740,7 @@ class SX126x: public PhysicalLayer {
     int16_t calibrateImage(uint8_t* data);
     uint8_t getPacketType();
     int16_t setTxParams(uint8_t power, uint8_t rampTime = SX126X_PA_RAMP_200U);
+    int16_t setOptimalHiPowerPaConfig(int8_t* inOutPower);
     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);