feat(uart): changes the uart loopback function to work with the P4

Author: SuGlider

cores/esp32/HardwareSerial.cpp

@@ -435,7 +435,6 @@ void HardwareSerial::end() {
   if (uartGetDebug() == _uart_nr) {
     uartSetDebug(0);
   }
-  uart_set_loop_back(_uart_nr, false);  // disable loopback mode, if previously enabled
   _rxFIFOFull = 0;
   uartEnd(_uart_nr);    // fully detach all pins and delete the UART driver
   _destroyEventTask();  // when IDF uart driver is deleted, _eventTask must finish too

cores/esp32/esp32-hal-uart.c

@@ -1166,11 +1166,11 @@ unsigned long uartDetectBaudrate(uart_t *uart) {
    This function internally binds defined UARTs TX signal with defined RX pin of any UART (same or different).
    This creates a loop that lets us receive anything we send on the UART without external wires.
 */
-void uart_internal_loopback(uint8_t uartNum, int8_t rxPin) {
-  if (uartNum > SOC_UART_HP_NUM - 1 || !GPIO_IS_VALID_GPIO(rxPin)) {
+void uart_internal_loopback(uint8_t uartNum, bool loop_back_en) {
+  if (uartNum > SOC_UART_HP_NUM - 1) {
     return;
   }
-  esp_rom_gpio_connect_out_signal(rxPin, UART_TX_SIGNAL(uartNum), false, false);
+  uart_set_loop_back(uartNum, loop_back_en);
 }
 
 /*

cores/esp32/esp32-hal-uart.h

@@ -106,7 +106,7 @@ unsigned long uartDetectBaudrate(uart_t *uart);
 
 // Make sure UART's RX signal is connected to TX pin
 // This creates a loop that lets us receive anything we send on the UART
-void uart_internal_loopback(uint8_t uartNum, int8_t rxPin);
+void uart_internal_loopback(uint8_t uartNum, bool loop_back_en);
 
 // Routines that generate BREAK in the UART for testing purpose