From 8acaca488402fae8481da9f16a6f859315ab3421 Mon Sep 17 00:00:00 2001
From: jgromes <jan.gromes@gmail.com>
Date: Sun, 25 Jun 2023 09:33:17 +0200
Subject: [PATCH] [SX127x] Swap Tx IQ inversion (#778)

---
 src/modules/SX127x/SX127x.cpp | 10 ++++++----
 src/modules/SX127x/SX127x.h   |  4 ++--
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/modules/SX127x/SX127x.cpp b/src/modules/SX127x/SX127x.cpp
index 467bbecd..4e9d5adc 100644
--- a/src/modules/SX127x/SX127x.cpp
+++ b/src/modules/SX127x/SX127x.cpp
@@ -1503,20 +1503,22 @@ void SX127x::clearFIFO(size_t count) {
   }
 }
 
-int16_t SX127x::invertIQ(bool invertIQ) {
+int16_t SX127x::invertIQ(bool enable) {
   // check active modem
   if(getActiveModem() != RADIOLIB_SX127X_LORA) {
     return(RADIOLIB_ERR_WRONG_MODEM);
   }
 
+  // Tx path inversion is swapped, because it seems that setting it according to the datsheet
+  // will actually lead to the wrong inversion. See https://github.com/jgromes/RadioLib/issues/778
   int16_t state;
-  if(invertIQ) {
+  if(enable) {
     state = this->mod->SPIsetRegValue(RADIOLIB_SX127X_REG_INVERT_IQ, RADIOLIB_SX127X_INVERT_IQ_RXPATH_ON, 6, 6);
-    state |= this->mod->SPIsetRegValue(RADIOLIB_SX127X_REG_INVERT_IQ, RADIOLIB_SX127X_INVERT_IQ_TXPATH_ON, 0, 0);
+    state |= this->mod->SPIsetRegValue(RADIOLIB_SX127X_REG_INVERT_IQ, RADIOLIB_SX127X_INVERT_IQ_TXPATH_OFF, 0, 0);
     state |= this->mod->SPIsetRegValue(RADIOLIB_SX127X_REG_INVERT_IQ2, RADIOLIB_SX127X_IQ2_ENABLE);
   } else {
     state = this->mod->SPIsetRegValue(RADIOLIB_SX127X_REG_INVERT_IQ, RADIOLIB_SX127X_INVERT_IQ_RXPATH_OFF, 6, 6);
-    state |= this->mod->SPIsetRegValue(RADIOLIB_SX127X_REG_INVERT_IQ, RADIOLIB_SX127X_INVERT_IQ_TXPATH_OFF, 0, 0);
+    state |= this->mod->SPIsetRegValue(RADIOLIB_SX127X_REG_INVERT_IQ, RADIOLIB_SX127X_INVERT_IQ_TXPATH_ON, 0, 0);
     state |= this->mod->SPIsetRegValue(RADIOLIB_SX127X_REG_INVERT_IQ2, RADIOLIB_SX127X_IQ2_DISABLE);
   }
 
diff --git a/src/modules/SX127x/SX127x.h b/src/modules/SX127x/SX127x.h
index 951ee31b..dcd84790 100644
--- a/src/modules/SX127x/SX127x.h
+++ b/src/modules/SX127x/SX127x.h
@@ -1086,10 +1086,10 @@ class SX127x: public PhysicalLayer {
 
     /*!
       \brief Enable/disable inversion of the I and Q signals
-      \param invertIQ QI inversion enabled (true) or disabled (false);
+      \param enable QI inversion enabled (true) or disabled (false);
       \returns \ref status_codes
     */
-    int16_t invertIQ(bool invertIQ);
+    int16_t invertIQ(bool enable);
 
     #if !defined(RADIOLIB_EXCLUDE_DIRECT_RECEIVE)
     /*!