Simple i/f to turn on inverted logic on UART0.

Author: dok-net

cores/esp8266/HardwareSerial.cpp

@@ -36,10 +36,14 @@ HardwareSerial::HardwareSerial(int uart_nr)
     : _uart_nr(uart_nr), _rx_size(256)
 {}
 
-void HardwareSerial::begin(unsigned long baud, SerialConfig config, SerialMode mode, uint8_t tx_pin)
+void HardwareSerial::begin(unsigned long baud, SerialConfig config, SerialMode mode, uint8_t tx_pin, bool invert)
 {
     end();
     _uart = uart_init(_uart_nr, baud, (int) config, (int) mode, tx_pin, _rx_size);
+    if (0 == _uart_nr && invert)
+    {
+        U0C0 |= BIT(UCDTRI) | BIT(UCRTSI) | BIT(UCTXI) | BIT(UCDSRI) | BIT(UCCTSI) | BIT(UCRXI);
+    }
 #if defined(DEBUG_ESP_PORT) && !defined(NDEBUG)
     if (static_cast<void*>(this) == static_cast<void*>(&DEBUG_ESP_PORT))
     {

cores/esp8266/HardwareSerial.h

@@ -84,7 +84,7 @@ class HardwareSerial: public Stream
         begin(baud, config, mode, 1);
     }
 
-    void begin(unsigned long baud, SerialConfig config, SerialMode mode, uint8_t tx_pin);
+    void begin(unsigned long baud, SerialConfig config, SerialMode mode, uint8_t tx_pin, bool invert=false);
 
     void end();