[LR11x0] Calibrate image based on frequency change

src/modules/LR11x0/LR1110.cpp

@@ -1,4 +1,6 @@
 #include "LR1110.h"
+#include <math.h>
+
 #if !RADIOLIB_EXCLUDE_LR11X0
 
 LR1110::LR1110(Module* mod) : LR11x0(mod) {
@@ -45,20 +47,24 @@ int16_t LR1110::beginLRFHSS(float freq, uint8_t bw, uint8_t cr, bool narrowGrid,
 }
 
 int16_t LR1110::setFrequency(float freq) {
-  return(this->setFrequency(freq, true));
+  return(this->setFrequency(freq, false));
 }
 
-int16_t LR1110::setFrequency(float freq, bool calibrate, float band) {
+int16_t LR1110::setFrequency(float freq, bool skipCalibration, float band) {
   RADIOLIB_CHECK_RANGE(freq, 150.0, 960.0, RADIOLIB_ERR_INVALID_FREQUENCY);
   
-  // calibrate image rejection
+  // check if we need to recalibrate image
-  if(calibrate) {
+  int16_t state;
-    int16_t state = LR11x0::calibImage(freq - band, freq + band);
+  if(!skipCalibration && (fabsf(freq - this->freqMHz) >= RADIOLIB_LR11X0_CAL_IMG_FREQ_TRIG_MHZ)) {
+    state = LR11x0::calibrateImageRejection(freq - band, freq + band);
     RADIOLIB_ASSERT(state);
   }
 
   // set frequency
-  return(LR11x0::setRfFrequency((uint32_t)(freq*1000000.0f)));
+  state = LR11x0::setRfFrequency((uint32_t)(freq*1000000.0f));
+  RADIOLIB_ASSERT(state);
+  this->freqMHz = freq;
+  return(state);
 }
 
 int16_t LR1110::setOutputPower(int8_t power) {

src/modules/LR11x0/LR1110.h

@@ -71,7 +71,8 @@ class LR1110: public LR11x0 {
 
     /*!
       \brief Sets carrier frequency. Allowed values are in range from 150.0 to 960.0 MHz.
-      Will also perform calibrations.
+      Will automatically perform image calibration if the frequency changes by
+      more than RADIOLIB_LR11X0_CAL_IMG_FREQ_TRIG MHz.
       \param freq Carrier frequency to be set in MHz.
       \returns \ref status_codes
     */
@@ -79,14 +80,16 @@ class LR1110: public LR11x0 {
 
     /*!
       \brief Sets carrier frequency. Allowed values are in range from 150.0 to 960.0 MHz.
+      Will automatically perform image calibration if the frequency changes by
+      more than RADIOLIB_LR11X0_CAL_IMG_FREQ_TRIG MHz.
       \param freq Carrier frequency to be set in MHz.
-      \param calibrate Run image calibration.
+      \param skipCalibration Skip automated image calibration.
       \param band Half bandwidth for image calibration. For example,
       if carrier is 434 MHz and band is set to 4 MHz, then the image will be calibrate
       for band 430 - 438 MHz. Unused if calibrate is set to false, defaults to 4 MHz
       \returns \ref status_codes
     */
-    int16_t setFrequency(float freq, bool calibrate, float band = 4);
+    int16_t setFrequency(float freq, bool skipCalibration, float band = 4);
     
     /*!
       \brief Sets output power. Allowed values are in range from -9 to 22 dBm (high-power PA) or -17 to 14 dBm (low-power PA).

src/modules/LR11x0/LR1120.cpp

@@ -1,4 +1,6 @@
 #include "LR1120.h"
+#include <math.h>
+
 #if !RADIOLIB_EXCLUDE_LR11X0
 
 LR1120::LR1120(Module* mod) : LR11x0(mod) {
@@ -45,26 +47,27 @@ int16_t LR1120::beginLRFHSS(float freq, uint8_t bw, uint8_t cr, bool narrowGrid,
 }
 
 int16_t LR1120::setFrequency(float freq) {
-  return(this->setFrequency(freq, true));
+  return(this->setFrequency(freq, false));
 }
 
-int16_t LR1120::setFrequency(float freq, bool calibrate, float band) {
+int16_t LR1120::setFrequency(float freq, bool skipCalibration, float band) {
   if(!(((freq >= 150.0) && (freq <= 960.0)) ||
     ((freq >= 1900.0) && (freq <= 2200.0)) ||
     ((freq >= 2400.0) && (freq <= 2500.0)))) {
       return(RADIOLIB_ERR_INVALID_FREQUENCY);
   }
 
-  // calibrate image rejection
+  // check if we need to recalibrate image
   int16_t state;
-  if(calibrate) {
+  if(!skipCalibration && (fabsf(freq - this->freqMHz) >= RADIOLIB_LR11X0_CAL_IMG_FREQ_TRIG_MHZ)) {
-    state = LR11x0::calibImage(freq - band, freq + band);
+    state = LR11x0::calibrateImageRejection(freq - band, freq + band);
     RADIOLIB_ASSERT(state);
   }
 
   // set frequency
   state = LR11x0::setRfFrequency((uint32_t)(freq*1000000.0f));
   RADIOLIB_ASSERT(state);
+  this->freqMHz = freq;
   this->highFreq = (freq > 1000.0);
   return(RADIOLIB_ERR_NONE);
 }

src/modules/LR11x0/LR1120.h

@@ -71,7 +71,9 @@ class LR1120: public LR11x0 {
 
     /*!
       \brief Sets carrier frequency. Allowed values are in range from 150.0 to 960.0 MHz,
-      1900 - 2200 MHz and 2400 - 2500 MHz. Will also perform calibrations.
+      1900 - 2200 MHz and 2400 - 2500 MHz.
+      Will automatically perform image calibration if the frequency changes by
+      more than RADIOLIB_LR11X0_CAL_IMG_FREQ_TRIG MHz.
       NOTE: When switching between sub-GHz and high-frequency bands, after changing the frequency,
       setOutputPower() must be called in order to set the correct power amplifier!
       \param freq Carrier frequency to be set in MHz.
@@ -81,17 +83,19 @@ class LR1120: public LR11x0 {
 
     /*!
       \brief Sets carrier frequency. Allowed values are in range from 150.0 to 960.0 MHz,
-      1900 - 2200 MHz and 2400 - 2500 MHz. Will also perform calibrations.
+      1900 - 2200 MHz and 2400 - 2500 MHz.
+      Will automatically perform image calibration if the frequency changes by
+      more than RADIOLIB_LR11X0_CAL_IMG_FREQ_TRIG MHz.
       NOTE: When switching between sub-GHz and high-frequency bands, after changing the frequency,
       setOutputPower() must be called in order to set the correct power amplifier!
       \param freq Carrier frequency to be set in MHz.
-      \param calibrate Run image calibration.
+      \param skipCalibration Skip automated image calibration.
       \param band Half bandwidth for image calibration. For example,
       if carrier is 434 MHz and band is set to 4 MHz, then the image will be calibrate
       for band 430 - 438 MHz. Unused if calibrate is set to false, defaults to 4 MHz
       \returns \ref status_codes
     */
-    int16_t setFrequency(float freq, bool calibrate, float band = 4);
+    int16_t setFrequency(float freq, bool skipCalibration, float band = 4);
 
     /*!
       \brief Sets output power. Allowed values are in range from -9 to 22 dBm (high-power PA) or -17 to 14 dBm (low-power PA).

src/modules/LR11x0/LR11x0.cpp

@@ -2400,10 +2400,10 @@ int16_t LR11x0::setRegMode(uint8_t mode) {
   return(this->SPIcommand(RADIOLIB_LR11X0_CMD_SET_REG_MODE, true, &mode, 1));
 }
 
-int16_t LR11x0::calibImage(float freq1, float freq2) {
+int16_t LR11x0::calibrateImageRejection(float freqMin, float freqMax) {
   uint8_t buff[2] = {
-    (uint8_t)floor((freq1 - 1.0f) / 4.0f),
+    (uint8_t)floor((freqMin - 1.0f) / 4.0f),
-    (uint8_t)ceil((freq2 + 1.0f) / 4.0f)
+    (uint8_t)ceil((freqMax + 1.0f) / 4.0f)
   };
   return(this->SPIcommand(RADIOLIB_LR11X0_CMD_CALIB_IMAGE, true, buff, sizeof(buff)));
 }

src/modules/LR11x0/LR11x0.h

@@ -233,6 +233,7 @@
 #define RADIOLIB_LR11X0_CALIBRATE_HF_RC                         (0x01UL << 1)   //  1     1                high frequency RC
 #define RADIOLIB_LR11X0_CALIBRATE_LF_RC                         (0x01UL << 0)   //  0     0                low frequency RC
 #define RADIOLIB_LR11X0_CALIBRATE_ALL                           (0x3FUL << 0)   //  5     0                everything
+#define RADIOLIB_LR11X0_CAL_IMG_FREQ_TRIG_MHZ                   (20.0)
 
 // RADIOLIB_LR11X0_CMD_SET_REG_MODE
 #define RADIOLIB_LR11X0_REG_MODE_LDO                            (0x00UL << 0)   //  0     0     regulator mode: LDO in all modes
@@ -1610,6 +1611,15 @@ class LR11x0: public PhysicalLayer {
     */
     int16_t getModem(ModemType_t* modem) override;
 
+    /*!
+      \brief Perform image rejection calibration for the specified frequency band.
+      WARNING: Use at your own risk! Setting incorrect values may lead to decreased performance
+      \param freqMin Frequency band lower bound.
+      \param freqMax Frequency band upper bound.
+      \returns \ref status_codes
+    */
+    int16_t calibrateImageRejection(float freqMin, float freqMax);
+    
 #if !RADIOLIB_GODMODE && !RADIOLIB_LOW_LEVEL
   protected:
 #endif
@@ -1629,7 +1639,6 @@ class LR11x0: public PhysicalLayer {
     int16_t clearErrors(void);
     int16_t calibrate(uint8_t params);
     int16_t setRegMode(uint8_t mode);
-    int16_t calibImage(float freq1, float freq2);
     int16_t setDioAsRfSwitch(uint8_t en, uint8_t stbyCfg, uint8_t rxCfg, uint8_t txCfg, uint8_t txHpCfg, uint8_t txHfCfg, uint8_t gnssCfg, uint8_t wifiCfg);
     int16_t setDioIrqParams(uint32_t irq1, uint32_t irq2);
     int16_t setDioIrqParams(uint32_t irq);
@@ -1790,6 +1799,7 @@ class LR11x0: public PhysicalLayer {
   protected:
 #endif
     uint8_t chipType = 0;
+    float freqMHz = 0;
 
 #if !RADIOLIB_GODMODE
   private: