Implement invert for HardwareSerial (#6816)

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

* Refactor invert from HardwareSerial to uart

* Final refactoring of invert bits into config bitmap.

* Overload instead of default arg for subclassing.

* Prevent unwanted effects if setting invert on other than UART0 - only that has these flags defined and documented.

Author: dok-net

cores/esp8266/HardwareSerial.cpp

@@ -36,10 +36,10 @@ 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);
+    _uart = uart_init(_uart_nr, baud, (int) config, (int) mode, tx_pin, _rx_size, invert);
 #if defined(DEBUG_ESP_PORT) && !defined(NDEBUG)
     if (static_cast<void*>(this) == static_cast<void*>(&DEBUG_ESP_PORT))
     {

cores/esp8266/HardwareSerial.h

@@ -73,18 +73,23 @@ class HardwareSerial: public Stream
 
     void begin(unsigned long baud)
     {
-        begin(baud, SERIAL_8N1, SERIAL_FULL, 1);
+        begin(baud, SERIAL_8N1, SERIAL_FULL, 1, false);
     }
     void begin(unsigned long baud, SerialConfig config)
     {
-        begin(baud, config, SERIAL_FULL, 1);
+        begin(baud, config, SERIAL_FULL, 1, false);
     }
     void begin(unsigned long baud, SerialConfig config, SerialMode mode)
     {
-        begin(baud, config, mode, 1);
+        begin(baud, config, mode, 1, false);
     }
 
-    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)
+    {
+        begin(baud, config, mode, tx_pin, false);
+    }
+
+    void begin(unsigned long baud, SerialConfig config, SerialMode mode, uint8_t tx_pin, bool invert);
 
     void end();
 

cores/esp8266/uart.cpp

@@ -577,7 +577,7 @@ uart_get_baudrate(uart_t* uart)
 }
 
 uart_t*
-uart_init(int uart_nr, int baudrate, int config, int mode, int tx_pin, size_t rx_size)
+uart_init(int uart_nr, int baudrate, int config, int mode, int tx_pin, size_t rx_size, bool invert)
 {
     uart_t* uart = (uart_t*) malloc(sizeof(uart_t));
     if(uart == NULL)
@@ -657,6 +657,10 @@ uart_init(int uart_nr, int baudrate, int config, int mode, int tx_pin, size_t rx
     }
 
     uart_set_baudrate(uart, baudrate);
+    if(uart->uart_nr == UART0 && invert)
+    {
+        config |= BIT(UCDTRI) | BIT(UCRTSI) | BIT(UCTXI) | BIT(UCDSRI) | BIT(UCCTSI) | BIT(UCRXI);
+    }
     USC0(uart->uart_nr) = config;
 
     if(!gdbstub_has_uart_isr_control() || uart->uart_nr != UART0) {

cores/esp8266/uart.h

@@ -113,7 +113,7 @@ extern "C" {
 struct uart_;
 typedef struct uart_ uart_t;
 
-uart_t* uart_init(int uart_nr, int baudrate, int config, int mode, int tx_pin, size_t rx_size);
+uart_t* uart_init(int uart_nr, int baudrate, int config, int mode, int tx_pin, size_t rx_size, bool invert);
 void uart_uninit(uart_t* uart);
 
 void uart_swap(uart_t* uart, int tx_pin);

tests/host/common/MockUART.cpp

@@ -323,10 +323,11 @@ uart_get_bit_length(const int uart_nr)
 }
 
 uart_t*
-uart_init(int uart_nr, int baudrate, int config, int mode, int tx_pin, size_t rx_size)
+uart_init(int uart_nr, int baudrate, int config, int mode, int tx_pin, size_t rx_size, bool invert)
 {
 	(void) config;
 	(void) tx_pin;
+	(void) invert;
 	uart_t* uart = (uart_t*) malloc(sizeof(uart_t));
 	if(uart == NULL)
 		return NULL;