From 2ae0188e50399739720c8cfa75ab849170d379b7 Mon Sep 17 00:00:00 2001
From: Libor Tomsik <libor@tomsik.eu>
Date: Thu, 15 Apr 2021 08:05:05 +0200
Subject: [PATCH 1/6] Created method for setting AFC bandwidth

---
 src/modules/SX127x/SX127x.cpp | 58 +++++++++++++++++++++++------------
 src/modules/SX127x/SX127x.h   | 20 ++++++++++--
 2 files changed, 56 insertions(+), 22 deletions(-)

diff --git a/src/modules/SX127x/SX127x.cpp b/src/modules/SX127x/SX127x.cpp
index b508cd7c..ae9f3995 100644
--- a/src/modules/SX127x/SX127x.cpp
+++ b/src/modules/SX127x/SX127x.cpp
@@ -84,8 +84,15 @@ int16_t SX127x::beginFSK(uint8_t chipVersion, float br, float freqDev, float rxB
   state = SX127x::setBitRate(br);
   RADIOLIB_ASSERT(state);
 
-  // set frequency deviation
-  state = SX127x::setFrequencyDeviation(freqDev);
+  // set receiver bandwidth
+  state = SX127x::setRxBandwidth(rxBw);
+  RADIOLIB_ASSERT(state);
+
+  //set AFC bandwidth
+  state = SX127x::setAFCBandwidth(rxBw);
+  RADIOLIB_ASSERT(state);
+
+  state = _mod->SPIsetRegValue(SX127X_REG_RX_CONFIG, 0x1E);//TODO
   RADIOLIB_ASSERT(state);
 
   // set receiver bandwidth
@@ -731,6 +738,19 @@ int16_t SX127x::setFrequencyDeviation(float freqDev) {
   return(state);
 }
 
+uint8_t SX127x::calculateBWManExp(float bandwidth) const
+{
+  for(uint8_t e = 7; e >= 1; e--) {
+    for(int8_t m = 2; m >= 0; m--) {
+      float point = (SX127X_CRYSTAL_FREQ * 1000000.0)/(((4 * m) + 16) * ((uint32_t)1 << (e + 2)));
+      if(abs(bandwidth - ((point / 1000.0) + 0.05)) <= 0.5) {
+        return((m << 3) | e);
+      }
+    }
+  }
+  return 0;
+}
+
 int16_t SX127x::setRxBandwidth(float rxBw) {
   // check active modem
   if(getActiveModem() != SX127X_FSK_OOK) {
@@ -743,26 +763,24 @@ int16_t SX127x::setRxBandwidth(float rxBw) {
   int16_t state = setMode(SX127X_STANDBY);
   RADIOLIB_ASSERT(state);
 
-  // calculate exponent and mantissa values
-  for(uint8_t e = 7; e >= 1; e--) {
-    for(int8_t m = 2; m >= 0; m--) {
-      float point = (SX127X_CRYSTAL_FREQ * 1000000.0)/(((4 * m) + 16) * ((uint32_t)1 << (e + 2)));
-      if(abs(rxBw - ((point / 1000.0) + 0.05)) <= 0.5) {
-        // set Rx bandwidth during AFC
-        state = _mod->SPIsetRegValue(SX127X_REG_AFC_BW, (m << 3) | e, 4, 0);
-        RADIOLIB_ASSERT(state);
+  // set Rx bandwidth
+  return(_mod->SPIsetRegValue(SX127X_REG_RX_BW, calculateBWManExp(rxBw), 4, 0));
+}
 
-        // set Rx bandwidth
-        state = _mod->SPIsetRegValue(SX127X_REG_RX_BW, (m << 3) | e, 4, 0);
-        if(state == ERR_NONE) {
-          SX127x::_rxBw = rxBw;
-        }
-
-        return(state);
-      }
+int16_t SX127x::setAFCBandwidth(float rxBw){
+    // check active modem
+    if(getActiveModem() != SX127X_FSK_OOK){
+        return(ERR_WRONG_MODEM);
     }
-  }
-  return(ERR_UNKNOWN);
+
+    RADIOLIB_CHECK_RANGE(rxBw, 2.6, 250.0, ERR_INVALID_RX_BANDWIDTH);
+
+    // set mode to STANDBY
+    int16_t state = setMode(SX127X_STANDBY);
+    RADIOLIB_ASSERT(state);
+
+    // set AFC bandwidth
+    return(_mod->SPIsetRegValue(SX127X_REG_AFC_BW, calculateBWManExp(rxBw), 4, 0));
 }
 
 int16_t SX127x::setSyncWord(uint8_t* syncWord, size_t len) {
diff --git a/src/modules/SX127x/SX127x.h b/src/modules/SX127x/SX127x.h
index 5ed17ddb..7508f6c6 100644
--- a/src/modules/SX127x/SX127x.h
+++ b/src/modules/SX127x/SX127x.h
@@ -814,6 +814,15 @@ class SX127x: public PhysicalLayer {
     */
     int16_t setRxBandwidth(float rxBw);
 
+    /*!
+      \brief Sets FSK automatic frequency correction bandwidth. Allowed values range from 2.6 to 250 kHz. Only available in FSK mode.
+
+      \param rxBw Receiver AFC bandwidth to be set (in kHz).
+
+      \returns \ref status_codes
+    */
+    int16_t setAFCBandwidth(float afcBw);
+
     /*!
       \brief Sets FSK sync word. Allowed sync words are up to 8 bytes long and can not contain null bytes. Only available in FSK mode.
 
@@ -993,7 +1002,7 @@ class SX127x: public PhysicalLayer {
     int16_t invertIQ(bool invertIQ);
 
 #if !defined(RADIOLIB_GODMODE) && !defined(RADIOLIB_LOW_LEVEL)
-  protected:
+protected:
 #endif
     Module* _mod;
 
@@ -1006,7 +1015,6 @@ class SX127x: public PhysicalLayer {
     uint8_t _sf = 0;
     uint8_t _cr = 0;
     float _br = 0;
-    float _rxBw = 0;
     bool _ook = false;
     bool _crcEnabled = false;
     size_t _packetLength = 0;
@@ -1030,6 +1038,14 @@ class SX127x: public PhysicalLayer {
     int16_t setActiveModem(uint8_t modem);
     void clearIRQFlags();
     void clearFIFO(size_t count); // used mostly to clear remaining bytes in FIFO after a packet read
+    /**
+     * @brief Calculate exponent and mantissa values for receiver bandwidth and AFC
+     *
+     * \param bandwidth bandwidth to be set (in kHz).
+     *
+     * \returns bandwidth in manitsa and exponent format
+     */
+    uint8_t calculateBWManExp(float bandwidth) const;
 };
 
 #endif

From ac4ea556ae18ee45516c0d9439d1550f3d0853f3 Mon Sep 17 00:00:00 2001
From: Libor Tomsik <libor@tomsik.eu>
Date: Thu, 15 Apr 2021 08:37:47 +0200
Subject: [PATCH 2/6] Implemented AFC&AGC trigger control

---
 src/modules/SX127x/SX127x.cpp | 45 ++++++++++++++++++++++++++---------
 src/modules/SX127x/SX127x.h   | 18 ++++++++++++++
 2 files changed, 52 insertions(+), 11 deletions(-)

diff --git a/src/modules/SX127x/SX127x.cpp b/src/modules/SX127x/SX127x.cpp
index ae9f3995..2cd50cd1 100644
--- a/src/modules/SX127x/SX127x.cpp
+++ b/src/modules/SX127x/SX127x.cpp
@@ -92,7 +92,11 @@ int16_t SX127x::beginFSK(uint8_t chipVersion, float br, float freqDev, float rxB
   state = SX127x::setAFCBandwidth(rxBw);
   RADIOLIB_ASSERT(state);
 
-  state = _mod->SPIsetRegValue(SX127X_REG_RX_CONFIG, 0x1E);//TODO
+  //sets AFC&AGC trigger to RSSI and preamble detect
+  state = SX127x::setAFCAGCTrigger(SX127X_RX_TRIGGER_BOTH);
+  RADIOLIB_ASSERT(state);
+
+  state = SX127x::setAFC(true);
   RADIOLIB_ASSERT(state);
 
   // set receiver bandwidth
@@ -768,19 +772,38 @@ int16_t SX127x::setRxBandwidth(float rxBw) {
 }
 
 int16_t SX127x::setAFCBandwidth(float rxBw){
-    // check active modem
-    if(getActiveModem() != SX127X_FSK_OOK){
-        return(ERR_WRONG_MODEM);
-    }
+  // check active modem
+  if(getActiveModem() != SX127X_FSK_OOK){
+      return(ERR_WRONG_MODEM);
+  }
 
-    RADIOLIB_CHECK_RANGE(rxBw, 2.6, 250.0, ERR_INVALID_RX_BANDWIDTH);
+  RADIOLIB_CHECK_RANGE(rxBw, 2.6, 250.0, ERR_INVALID_RX_BANDWIDTH);
 
-    // set mode to STANDBY
-    int16_t state = setMode(SX127X_STANDBY);
-    RADIOLIB_ASSERT(state);
+  // set mode to STANDBY
+  int16_t state = setMode(SX127X_STANDBY);
+  RADIOLIB_ASSERT(state);
 
-    // set AFC bandwidth
-    return(_mod->SPIsetRegValue(SX127X_REG_AFC_BW, calculateBWManExp(rxBw), 4, 0));
+  // set AFC bandwidth
+  return(_mod->SPIsetRegValue(SX127X_REG_AFC_BW, calculateBWManExp(rxBw), 4, 0));
+}
+
+int16_t SX127x::setAFC(bool isEnabled){
+  // check active modem
+  if(getActiveModem() != SX127X_FSK_OOK) {
+    return(ERR_WRONG_MODEM);
+  }
+
+  //set AFC auto on/off
+  return(_mod->SPIsetRegValue(SX127X_REG_RX_CONFIG, isEnabled ? SX127X_AFC_AUTO_ON : SX127X_AFC_AUTO_OFF, 4, 4));
+}
+
+int16_t SX127x::setAFCAGCTrigger(uint8_t trigger){
+  if(getActiveModem() != SX127X_FSK_OOK) {
+    return(ERR_WRONG_MODEM);
+  }
+
+  //set AFC&AGC trigger
+  return(_mod->SPIsetRegValue(SX127X_REG_RX_CONFIG, trigger, 2, 0));
 }
 
 int16_t SX127x::setSyncWord(uint8_t* syncWord, size_t len) {
diff --git a/src/modules/SX127x/SX127x.h b/src/modules/SX127x/SX127x.h
index 7508f6c6..e16c8cdf 100644
--- a/src/modules/SX127x/SX127x.h
+++ b/src/modules/SX127x/SX127x.h
@@ -823,6 +823,24 @@ class SX127x: public PhysicalLayer {
     */
     int16_t setAFCBandwidth(float afcBw);
 
+    /*!
+      \brief Enables or disables FSK automatic frequency correction(AFC)
+
+      \param isEnabled AFC enabled or disabled
+
+      \return \ref status_codes
+    */
+    int16_t setAFC(bool isEnabled);
+
+    /*!
+      \brief Controls trigger of AFC and AGC
+
+      \param trigger one from SX127X_RX_TRIGGER_NONE, SX127X_RX_TRIGGER_RSSI_INTERRUPT, SX127X_RX_TRIGGER_PREAMBLE_DETECT, SX127X_RX_TRIGGER_BOTH
+
+      \return \ref status_codes
+    */
+    int16_t setAFCAGCTrigger(uint8_t trigger);
+
     /*!
       \brief Sets FSK sync word. Allowed sync words are up to 8 bytes long and can not contain null bytes. Only available in FSK mode.
 

From 555b90abfa702d03dc3c8956af1dd125af016929 Mon Sep 17 00:00:00 2001
From: Libor Tomsik <libor@tomsik.eu>
Date: Thu, 15 Apr 2021 09:13:46 +0200
Subject: [PATCH 3/6] Revering unvanted changes

---
 src/modules/SX127x/SX127x.cpp | 6 +++---
 src/modules/SX127x/SX127x.h   | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/modules/SX127x/SX127x.cpp b/src/modules/SX127x/SX127x.cpp
index 2cd50cd1..ccdcec12 100644
--- a/src/modules/SX127x/SX127x.cpp
+++ b/src/modules/SX127x/SX127x.cpp
@@ -84,8 +84,8 @@ int16_t SX127x::beginFSK(uint8_t chipVersion, float br, float freqDev, float rxB
   state = SX127x::setBitRate(br);
   RADIOLIB_ASSERT(state);
 
-  // set receiver bandwidth
-  state = SX127x::setRxBandwidth(rxBw);
+  // set frequency deviation
+  state = SX127x::setFrequencyDeviation(freqDev);
   RADIOLIB_ASSERT(state);
 
   //set AFC bandwidth
@@ -1219,7 +1219,7 @@ bool SX127x::findChip(uint8_t ver) {
 }
 
 int16_t SX127x::setMode(uint8_t mode) {
-  return(_mod->SPIsetRegValue(SX127X_REG_OP_MODE, mode, 2, 0, 5));
+  return(_mod->SPIsetRegValue(SX127X_REG_OP_MODE, mode, 2, 0, 2));
 }
 
 int16_t SX127x::getActiveModem() {
diff --git a/src/modules/SX127x/SX127x.h b/src/modules/SX127x/SX127x.h
index e16c8cdf..b5621b22 100644
--- a/src/modules/SX127x/SX127x.h
+++ b/src/modules/SX127x/SX127x.h
@@ -1020,7 +1020,7 @@ class SX127x: public PhysicalLayer {
     int16_t invertIQ(bool invertIQ);
 
 #if !defined(RADIOLIB_GODMODE) && !defined(RADIOLIB_LOW_LEVEL)
-protected:
+  protected:
 #endif
     Module* _mod;
 

From cbe145b9f72948a473feaaacb2412cf671e68364 Mon Sep 17 00:00:00 2001
From: Libor Tomsik <libor@tomsik.eu>
Date: Thu, 15 Apr 2021 09:15:53 +0200
Subject: [PATCH 4/6] Setting setMode timetout back to 2ms

---
 src/modules/SX127x/SX127x.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/modules/SX127x/SX127x.cpp b/src/modules/SX127x/SX127x.cpp
index ccdcec12..917560ad 100644
--- a/src/modules/SX127x/SX127x.cpp
+++ b/src/modules/SX127x/SX127x.cpp
@@ -1219,7 +1219,7 @@ bool SX127x::findChip(uint8_t ver) {
 }
 
 int16_t SX127x::setMode(uint8_t mode) {
-  return(_mod->SPIsetRegValue(SX127X_REG_OP_MODE, mode, 2, 0, 2));
+  return(_mod->SPIsetRegValue(SX127X_REG_OP_MODE, mode, 2, 0, 5));
 }
 
 int16_t SX127x::getActiveModem() {

From 37a0c56bfec870944194b48dc20dfc15eec5f3d8 Mon Sep 17 00:00:00 2001
From: Libor Tomsik <libor@tomsik.eu>
Date: Thu, 15 Apr 2021 12:50:49 +0200
Subject: [PATCH 5/6] Added method for reading current AFC value

---
 src/modules/SX127x/SX127x.cpp | 16 ++++++++++++++++
 src/modules/SX127x/SX127x.h   |  7 +++++++
 2 files changed, 23 insertions(+)

diff --git a/src/modules/SX127x/SX127x.cpp b/src/modules/SX127x/SX127x.cpp
index 917560ad..9d2e00ee 100644
--- a/src/modules/SX127x/SX127x.cpp
+++ b/src/modules/SX127x/SX127x.cpp
@@ -669,6 +669,22 @@ float SX127x::getFrequencyError(bool autoCorrect) {
   return(ERR_UNKNOWN);
 }
 
+float SX127x::getAFCError()
+{
+  // check active modem
+  int16_t modem = getActiveModem();
+  if(modem != SX127X_FSK_OOK) {
+    return 0;
+  }
+
+  // get raw frequency error
+  int16_t raw = (uint16_t)_mod->SPIgetRegValue(SX127X_REG_AFC_MSB) << 8;
+  raw |= _mod->SPIgetRegValue(SX127X_REG_AFC_LSB);
+
+  uint32_t base = 1;
+  return raw * (32000000.0 / (float)(base << 19));
+}
+
 float SX127x::getSNR() {
   // check active modem
   if(getActiveModem() != SX127X_LORA) {
diff --git a/src/modules/SX127x/SX127x.h b/src/modules/SX127x/SX127x.h
index b5621b22..66c5442b 100644
--- a/src/modules/SX127x/SX127x.h
+++ b/src/modules/SX127x/SX127x.h
@@ -773,6 +773,13 @@ class SX127x: public PhysicalLayer {
     */
     float getFrequencyError(bool autoCorrect = false);
 
+    /*!
+      \brief Gets current AFC error.
+
+      \returns Frequency offset from RF in Hz if AFC is enabled and triggered, zero otherwise.
+    */
+    float getAFCError();
+
     /*!
       \brief Gets signal-to-noise ratio of the latest received packet.
 

From b4a3049be0a73783fc5a17168f5775278b3dff8b Mon Sep 17 00:00:00 2001
From: Libor Tomsik <libor@tomsik.eu>
Date: Thu, 15 Apr 2021 21:33:58 +0200
Subject: [PATCH 6/6] Added keywords

---
 keywords.txt                  | 4 ++++
 src/modules/SX127x/SX127x.cpp | 6 +++---
 src/modules/SX127x/SX127x.h   | 2 +-
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/keywords.txt b/keywords.txt
index 34f66d67..46447d3a 100644
--- a/keywords.txt
+++ b/keywords.txt
@@ -104,10 +104,14 @@ setPreambleLength	KEYWORD2
 setGain	KEYWORD2
 getFrequencyError	KEYWORD2
 getRSSI	KEYWORD2
+getAFCError	KEYWORD2
 getSNR	KEYWORD2
 getDataRate	KEYWORD2
 setBitRate	KEYWORD2
 setRxBandwidth	KEYWORD2
+setAFCBandwidth	KEYWORD2
+setAFC		KEYWORD2
+setAFCAGCTrigger	KEYWORD2
 setFrequencyDeviation	KEYWORD2
 setNodeAddress	KEYWORD2
 setBroadcastAddress	KEYWORD2
diff --git a/src/modules/SX127x/SX127x.cpp b/src/modules/SX127x/SX127x.cpp
index 9d2e00ee..b4461d6b 100644
--- a/src/modules/SX127x/SX127x.cpp
+++ b/src/modules/SX127x/SX127x.cpp
@@ -678,8 +678,8 @@ float SX127x::getAFCError()
   }
 
   // get raw frequency error
-  int16_t raw = (uint16_t)_mod->SPIgetRegValue(SX127X_REG_AFC_MSB) << 8;
-  raw |= _mod->SPIgetRegValue(SX127X_REG_AFC_LSB);
+  int16_t raw = (uint16_t)_mod->SPIreadRegister(SX127X_REG_AFC_MSB) << 8;
+  raw |= _mod->SPIreadRegister(SX127X_REG_AFC_LSB);
 
   uint32_t base = 1;
   return raw * (32000000.0 / (float)(base << 19));
@@ -758,7 +758,7 @@ int16_t SX127x::setFrequencyDeviation(float freqDev) {
   return(state);
 }
 
-uint8_t SX127x::calculateBWManExp(float bandwidth) const
+uint8_t SX127x::calculateBWManExp(float bandwidth)
 {
   for(uint8_t e = 7; e >= 1; e--) {
     for(int8_t m = 2; m >= 0; m--) {
diff --git a/src/modules/SX127x/SX127x.h b/src/modules/SX127x/SX127x.h
index 66c5442b..6ffcb6b9 100644
--- a/src/modules/SX127x/SX127x.h
+++ b/src/modules/SX127x/SX127x.h
@@ -1070,7 +1070,7 @@ class SX127x: public PhysicalLayer {
      *
      * \returns bandwidth in manitsa and exponent format
      */
-    uint8_t calculateBWManExp(float bandwidth) const;
+    static uint8_t calculateBWManExp(float bandwidth);
 };
 
 #endif