From 8fcc91485364b334c51447686bc168e9160d093f Mon Sep 17 00:00:00 2001
From: brian-r-calder <brc@ccom.unh.edu>
Date: Thu, 1 Oct 2020 06:58:48 -0400
Subject: [PATCH] Added facility to invert the polarity of input UART bits.
 (#4200)

---
 cores/esp32/HardwareSerial.cpp |  5 +++++
 cores/esp32/HardwareSerial.h   |  2 ++
 cores/esp32/esp32-hal-uart.c   | 11 +++++++++++
 cores/esp32/esp32-hal-uart.h   |  2 ++
 4 files changed, 20 insertions(+)

diff --git a/cores/esp32/HardwareSerial.cpp b/cores/esp32/HardwareSerial.cpp
index a6c36293..b06e0735 100644
--- a/cores/esp32/HardwareSerial.cpp
+++ b/cores/esp32/HardwareSerial.cpp
@@ -184,3 +184,8 @@ HardwareSerial::operator bool() const
 {
     return true;
 }
+
+void HardwareSerial::setRxInvert(bool invert)
+{
+    uartSetRxInvert(_uart, invert);
+}
diff --git a/cores/esp32/HardwareSerial.h b/cores/esp32/HardwareSerial.h
index f6fab2a9..e776e939 100644
--- a/cores/esp32/HardwareSerial.h
+++ b/cores/esp32/HardwareSerial.h
@@ -100,6 +100,8 @@ public:
 
     size_t setRxBufferSize(size_t);
     void setDebugOutput(bool);
+    
+    void setRxInvert(bool);
 
 protected:
     int _uart_nr;
diff --git a/cores/esp32/esp32-hal-uart.c b/cores/esp32/esp32-hal-uart.c
index bc4a676b..cad5a1d4 100644
--- a/cores/esp32/esp32-hal-uart.c
+++ b/cores/esp32/esp32-hal-uart.c
@@ -266,6 +266,17 @@ size_t uartResizeRxBuffer(uart_t * uart, size_t new_size) {
     return new_size;
 }
 
+void uartSetRxInvert(uart_t* uart, bool invert)
+{
+    if (uart == NULL)
+        return;
+    
+    if (invert)
+        uart->dev->conf0.rxd_inv = 1;
+    else
+        uart->dev->conf0.rxd_inv = 0;
+}
+
 uint32_t uartAvailable(uart_t* uart)
 {
     if(uart == NULL || uart->queue == NULL) {
diff --git a/cores/esp32/esp32-hal-uart.h b/cores/esp32/esp32-hal-uart.h
index ffec2a45..e35f05d4 100644
--- a/cores/esp32/esp32-hal-uart.h
+++ b/cores/esp32/esp32-hal-uart.h
@@ -70,6 +70,8 @@ uint32_t uartGetBaudRate(uart_t* uart);
 
 size_t uartResizeRxBuffer(uart_t* uart, size_t new_size);
 
+void uartSetRxInvert(uart_t* uart, bool invert);
+
 void uartSetDebug(uart_t* uart);
 int uartGetDebug();