[ESP32] Allow user to define pins for hardware Serial1 and Serial2 (#16918)

Marlin/src/HAL/HAL_ESP32/HAL.cpp

@@ -27,6 +27,7 @@
 #include <rom/rtc.h>
 #include <driver/adc.h>
 #include <esp_adc_cal.h>
+#include <HardwareSerial.h>
 
 #include "../../inc/MarlinConfigPre.h"
 
@@ -105,6 +106,27 @@ void HAL_init_board() {
     #endif
     server.begin();
   #endif
+
+  // ESP32 uses a GPIO matrix that allows pins to be assigned to hardware serial ports.
+  // The following code initializes hardware Serial1 and Serial2 to use user-defined pins
+  // if they have been defined.
+  #if defined(HARDWARE_SERIAL1_RX) && defined(HARDWARE_SERIAL1_TX)
+    HardwareSerial Serial1(1);
+    #ifdef TMC_BAUD_RATE  // use TMC_BAUD_RATE for Serial1 if defined
+      Serial1.begin(TMC_BAUD_RATE, SERIAL_8N1, HARDWARE_SERIAL1_RX, HARDWARE_SERIAL1_TX);
+    #else  // use default BAUDRATE if TMC_BAUD_RATE not defined
+      Serial1.begin(BAUDRATE, SERIAL_8N1, HARDWARE_SERIAL1_RX, HARDWARE_SERIAL1_TX);
+    #endif
+  #endif
+  #if defined(HARDWARE_SERIAL2_RX) && defined(HARDWARE_SERIAL2_TX)
+    HardwareSerial Serial2(2);
+    #ifdef TMC_BAUD_RATE  // use TMC_BAUD_RATE for Serial1 if defined
+      Serial2.begin(TMC_BAUD_RATE, SERIAL_8N1, HARDWARE_SERIAL2_RX, HARDWARE_SERIAL2_TX);
+    #else  // use default BAUDRATE if TMC_BAUD_RATE not defined
+      Serial2.begin(BAUDRATE, SERIAL_8N1, HARDWARE_SERIAL2_RX, HARDWARE_SERIAL2_TX);
+    #endif
+  #endif
+
 }
 
 void HAL_idletask() {

Marlin/src/pins/esp32/pins_MRR_ESPA.h

@@ -101,3 +101,10 @@
 #define SDSS                5
 #define USES_SHARED_SPI  // SPI is shared by SD card with TMC SPI drivers
 
+// Hardware serial pins
+// Add the following to Configuration.h or Configuration_adv.h to assign
+// specific pins to hardware Serial1.
+// Note: Serial2 can be defined using HARDWARE_SERIAL2_RX and HARDWARE_SERIAL2_TX but
+// MRR ESPA does not have enough spare pins for such reassignment.
+//#define HARDWARE_SERIAL1_RX 21
+//#define HARDWARE_SERIAL1_TX 22

Marlin/src/pins/esp32/pins_MRR_ESPE.h

@@ -139,7 +139,7 @@
     #define BEEPER_PIN      151
 
     //#define LCD_PINS_D5     150
-    //#define LCD_PINS_D6     151
+    //#define LCD_PINS_D6     152
     //#define LCD_PINS_D7     153
 
   #else
@@ -153,3 +153,13 @@
   #define BTN_ENC            14
 
 #endif // HAS_GRAPHICAL_LCD
+
+// Hardware serial pins
+// Add the following to Configuration.h or Configuration_adv.h to assign
+// specific pins to hardware Serial1 and Serial2.
+// Note: Serial2 can be defined using HARDWARE_SERIAL2_RX and HARDWARE_SERIAL2_TX but
+// MRR ESPA does not have enough spare pins for such reassignment.
+//#define HARDWARE_SERIAL1_RX 21
+//#define HARDWARE_SERIAL1_TX 22
+//#define HARDWARE_SERIAL2_RX  2
+//#define HARDWARE_SERIAL2_TX  4