Allows setting only one pin (rx or tx) in the first begin() (espressif#6394)

Author: SuGlider

cores/esp32/HardwareSerial.cpp

@@ -261,19 +261,25 @@ void HardwareSerial::begin(unsigned long baud, uint32_t config, int8_t rxPin, in
  if (!uartIsDriverInstalled(_uart)) {
  switch (_uart_nr) {
  case UART_NUM_0:
- rxPin = rxPin < 0 ? SOC_RX0 : rxPin;
- txPin = txPin < 0 ? SOC_TX0 : txPin;
+ if (rxPin < 0 && txPin < 0) {
+ rxPin = SOC_RX0;
+ txPin = SOC_TX0;
+ }
  break;
 #if SOC_UART_NUM > 1 // may save some flash bytes...
  case UART_NUM_1:
- rxPin = rxPin < 0 ? RX1 : rxPin;
- txPin = txPin < 0 ? TX1 : txPin;
+ if (rxPin < 0 && txPin < 0) {
+ rxPin = RX1;
+ txPin = TX1;
+ }
  break;
 #endif
 #if SOC_UART_NUM > 2 // may save some flash bytes...
  case UART_NUM_2:
- rxPin = rxPin < 0 ? RX2 : rxPin;
- txPin = txPin < 0 ? TX2 : txPin;
+ if (rxPin < 0 && txPin < 0) {
+ rxPin = RX2;
+ txPin = TX2;
+ }
  break;
 #endif
  default: