From 8fc323a900a9885bb47beacbfa336a12a0a23524 Mon Sep 17 00:00:00 2001
From: Bernd Giesecke <bernd@giesecke.tk>
Date: Tue, 4 Jun 2019 13:13:00 +0800
Subject: [PATCH] Add function to set DIO2 of SX126x chips to be used as RF
 antenna switch (based on example design of Semtech and used in many modules).
 This breaks the CAD function as DIO2 cannot be used as IRQ output.

Signed-off-by: Bernd Giesecke <bernd@giesecke.tk>
---
 src/Module.cpp         |  4 ++++
 src/Module.h           | 16 +++++++++++++++-
 src/modules/SX126x.cpp | 28 ++++++++++++++++++++++++++++
 src/modules/SX126x.h   |  7 +++++++
 4 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/src/Module.cpp b/src/Module.cpp
index 5c238519..da2ac6f9 100644
--- a/src/Module.cpp
+++ b/src/Module.cpp
@@ -79,6 +79,10 @@ void Module::term() {
   _spi->end();
 }
 
+void Module::setDio2Func(bool enable) { 
+  _dio2RfSwitch = enable;
+}
+
 void Module::ATemptyBuffer() {
   while(ModuleSerial->available() > 0) {
     ModuleSerial->read();
diff --git a/src/Module.h b/src/Module.h
index c596276f..0ed6a3eb 100644
--- a/src/Module.h
+++ b/src/Module.h
@@ -277,6 +277,20 @@ class Module {
     */
     int getTx() const { return(_tx); }
 
+    /*!
+      \brief Access method to get DIO2 RF switch flag.
+
+      \returns true if DIO2 is set as RF switch.
+    */
+    int getDio2Func() const { return(_dio2RfSwitch); }
+
+    /*!
+      \brief Access method to set/reset DIO2 RF switch flag.
+
+      \returns true if DIO2 is set as RF switch.
+    */
+    void setDio2Func(bool enable);
+
     /*!
       \brief Access method to get the SPI interface.
 
@@ -297,7 +311,7 @@ class Module {
     int _rx;
     int _int0;
     int _int1;
-
+    bool _dio2RfSwitch = false;
     SPIClass* _spi;
     SPISettings _spiSettings;
 
diff --git a/src/modules/SX126x.cpp b/src/modules/SX126x.cpp
index 05274763..e43a774d 100644
--- a/src/modules/SX126x.cpp
+++ b/src/modules/SX126x.cpp
@@ -274,6 +274,11 @@ int16_t SX126x::scanChannel() {
     return(ERR_WRONG_MODEM);
   }
 
+  if (_mod->getDio2Func()) {
+    // If DIO2 is used as RF switch this function does not work
+    return(ERR_WRONG_MODEM);
+  }
+
   // set mode to standby
   int16_t state = standby();
   if(state != ERR_NONE) {
@@ -1058,6 +1063,29 @@ int16_t SX126x::setFrequencyRaw(float freq) {
   return(ERR_NONE);
 }
 
+int16_t SX126x::setDio2AsRfSwitch(bool enable) {
+  int dio2 = _mod->getInt1();
+  if (dio2 == -1)
+  {
+    // DIO2 is not defined, return error
+    _mod->setDio2Func(false);
+    return ERR_WRONG_MODEM;
+  }
+  uint8_t* data = new uint8_t[1];
+  if (enable) {
+  // set DIO2 as RF switch
+    data[0] = SX126X_DIO2_AS_RF_SWITCH;
+  } else {
+    data[0] = SX126X_DIO2_AS_IRQ;
+  }
+  int16_t state = SPIwriteCommand(SX126X_CMD_SET_DIO2_AS_RF_SWITCH_CTRL, data, 1);
+
+  if (state == ERR_NONE) {
+    _mod->setDio2Func(enable);
+  }
+  return(state);
+}
+
 int16_t SX126x::config(uint8_t modem) {
   // set DIO2 as IRQ
   uint8_t* data = new uint8_t[1];
diff --git a/src/modules/SX126x.h b/src/modules/SX126x.h
index a9a84b4b..1f34c759 100644
--- a/src/modules/SX126x.h
+++ b/src/modules/SX126x.h
@@ -678,6 +678,13 @@ class SX126x: public PhysicalLayer {
     */
     float getSNR();
 
+    /*!
+      \brief Set DIO2 to function as RF switch (default in Semtech example designs).
+
+      \returns \ref status_codes 
+    */
+    int16_t setDio2AsRfSwitch(bool enable = false);
+
   protected:
     // SX1276x SPI command implementations
     int16_t setTx(uint32_t timeout = 0);