ESP32-P4 UART Pin Definitions (#10521)

* feat(uart): allow pins_arduino.h to define esp32-p4 uart pins

ESP32-P4 has UART default pins only for UART0 and UART1.
This PR allows the board definition from pins_arduino.h to define RX2 ... RX4 and TX2 ... TX4 if necessary.
It also solves the issue of begin(baud) with no pins for UART2...4 by just sending a error message and returning.

* feat(uart): removes the uart2 pin definitions - not existant

* fix(uart): solves the case when uart has already been initialized

* ci(pre-commit): Apply automatic fixes

* fix(ci): uart definition for esp32-p4 uart2 rx,tx pins

---------

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

cores/esp32/HardwareSerial.cpp

@@ -313,6 +313,11 @@ void HardwareSerial::begin(unsigned long baud, uint32_t config, int8_t rxPin, in
   // map logical pins to GPIO numbers
   rxPin = digitalPinToGPIONumber(rxPin);
   txPin = digitalPinToGPIONumber(txPin);
+  int8_t _rxPin = uart_get_RxPin(_uart_nr);
+  int8_t _txPin = uart_get_TxPin(_uart_nr);
+
+  rxPin = rxPin < 0 ? _rxPin : rxPin;
+  txPin = txPin < 0 ? _txPin : txPin;
 
   HSERIAL_MUTEX_LOCK();
   // First Time or after end() --> set default Pins
@@ -341,14 +346,51 @@ void HardwareSerial::begin(unsigned long baud, uint32_t config, int8_t rxPin, in
       case UART_NUM_2:
         if (rxPin < 0 && txPin < 0) {
           // do not change RX2/TX2 if it has already been set before
+#ifdef RX2
           rxPin = _rxPin < 0 ? (int8_t)RX2 : _rxPin;
+#endif
+#ifdef TX2
           txPin = _txPin < 0 ? (int8_t)TX2 : _txPin;
+#endif
+        }
+        break;
+#endif
+#if SOC_UART_HP_NUM > 3  // may save some flash bytes...
+      case UART_NUM_3:
+        if (rxPin < 0 && txPin < 0) {
+          // do not change RX2/TX2 if it has already been set before
+#ifdef RX3
+          rxPin = _rxPin < 0 ? (int8_t)RX3 : _rxPin;
+#endif
+#ifdef TX3
+          txPin = _txPin < 0 ? (int8_t)TX3 : _txPin;
+#endif
+        }
+        break;
+#endif
+#if SOC_UART_HP_NUM > 4  // may save some flash bytes...
+      case UART_NUM_4:
+        if (rxPin < 0 && txPin < 0) {
+          // do not change RX2/TX2 if it has already been set before
+#ifdef RX4
+          rxPin = _rxPin < 0 ? (int8_t)RX4 : _rxPin;
+#endif
+#ifdef TX4
+          txPin = _txPin < 0 ? (int8_t)TX4 : _txPin;
+#endif
         }
         break;
 #endif
     }
   }
 
+  // if no RX/TX pins are defined, it will not start the UART driver
+  if (rxPin < 0 && txPin < 0) {
+    log_e("No RX/TX pins defined. Please set RX/TX pins.");
+    HSERIAL_MUTEX_UNLOCK();
+    return;
+  }
+
   // IDF UART driver keeps Pin setting on restarting. Negative Pin number will keep it unmodified.
   // it will detach previous UART attached pins
 

cores/esp32/HardwareSerial.h

@@ -200,8 +200,6 @@ typedef enum {
 #define RX2 (gpio_num_t)4
 #elif CONFIG_IDF_TARGET_ESP32S3
 #define RX2 (gpio_num_t)19
-#elif CONFIG_IDF_TARGET_ESP32P4
-#define RX2 (gpio_num_t)15
 #endif
 #endif
 
@@ -210,8 +208,6 @@ typedef enum {
 #define TX2 (gpio_num_t)25
 #elif CONFIG_IDF_TARGET_ESP32S3
 #define TX2 (gpio_num_t)20
-#elif CONFIG_IDF_TARGET_ESP32P4
-#define TX2 (gpio_num_t)14
 #endif
 #endif
 #endif /* SOC_UART_HP_NUM > 2 */

tests/validation/uart/uart.ino

@@ -52,6 +52,14 @@
 #define NEW_TX1 10
 #endif
 
+// ESP32-P4 has no UART pin definition for RX2, TX2, RX3, TX3, RX4, TX4
+#ifndef RX2
+#define RX2 RX1
+#endif
+#ifndef TX2
+#define TX2 RX1
+#endif
+
 /* Utility global variables */
 
 static String recv_msg = "";