MMU2 as standard serial device (#20771)

Marlin/Configuration_adv.h

   //#define E_MUX2_PIN 44  // Needed for 5 to 8 inputs
 #elif HAS_PRUSA_MMU2
   // Serial port used for communication with MMU2.
-  // For AVR enable the UART port used for the MMU. (e.g., mmuSerial)
-  // For 32-bit boards check your HAL for available serial ports. (e.g., Serial2)
   #define MMU2_SERIAL_PORT 2
-  #define MMU2_SERIAL mmuSerial
 
   // Use hardware reset for MMU if a pin is defined for it
   //#define MMU2_RST_PIN 23

Marlin/src/HAL/AVR/HAL.h

   #endif
 #endif
 
+#ifdef MMU2_SERIAL_PORT
+  #if !WITHIN(MMU2_SERIAL_PORT, -1, 3)
+    #error "MMU2_SERIAL_PORT must be from -1 to 3. Please update your configuration."
+  #endif
+  #define MMU2_SERIAL mmuSerial
+#endif
+
 #ifdef LCD_SERIAL_PORT
   #if !WITHIN(LCD_SERIAL_PORT, -1, 3)
     #error "LCD_SERIAL_PORT must be from -1 to 3. Please update your configuration."

Marlin/src/HAL/DUE/HAL.h

   #endif
 #endif
 
+#ifdef MMU2_SERIAL_PORT
+  #if WITHIN(MMU2_SERIAL_PORT, 0, 3)
+    #define MMU2_SERIAL MSERIAL(SERIAL_PORT)
+  #else
+    #error "MMU2_SERIAL_PORT must be from 0 to 3. Please update your configuration."
+  #endif
+#endif
+
 #ifdef LCD_SERIAL_PORT
   #if LCD_SERIAL_PORT == -1
     #define LCD_SERIAL lcdSerial

Marlin/src/HAL/LPC1768/HAL.h

   #endif
 #endif
 
+#ifdef MMU2_SERIAL_PORT
+  #if MMU2_SERIAL_PORT == -1
+    #define MMU2_SERIAL UsbSerial
+  #elif WITHIN(MMU2_SERIAL_PORT, 0, 3)
+    #define MMU2_SERIAL MSERIAL(MMU2_SERIAL_PORT)
+  #else
+    #error "MMU2_SERIAL_PORT must be from -1 to 3. Please update your configuration."
+  #endif
+#endif
+
 #ifdef LCD_SERIAL_PORT
   #if LCD_SERIAL_PORT == -1
     #define LCD_SERIAL UsbSerial

Marlin/src/HAL/SAMD51/HAL.h

     #endif
   #endif
 
+  #ifdef MMU2_SERIAL_PORT
+    #if MMU2_SERIAL_PORT == -1
+      #define MMU2_SERIAL Serial
+    #elif WITHIN(MMU2_SERIAL_PORT, 0, 3)
+      #define MMU2_SERIAL MSERIAL(MMU2_SERIAL_PORT)
+    #else
+      #error "MMU2_SERIAL_PORT must be from -1 to 3. Please update your configuration."
+    #endif
+  #endif
+
   #ifdef LCD_SERIAL_PORT
     #if LCD_SERIAL_PORT == -1
       #define LCD_SERIAL Serial

Marlin/src/HAL/SAMD51/MarlinSerial_AGCM4.cpp

 #ifdef ADAFRUIT_GRAND_CENTRAL_M4
 
 /**
- * Framework doesn't define some serial to save sercom resources
+ * Framework doesn't define some serials to save sercom resources
  * hence if these are used I need to define them
  */
 
 #include "../../inc/MarlinConfig.h"
 
-#if SERIAL_PORT == 1 || SERIAL_PORT_2 == 1
+#if USING_SERIAL_1
   Uart Serial2(&sercom4, PIN_SERIAL2_RX, PIN_SERIAL2_TX, PAD_SERIAL2_RX, PAD_SERIAL2_TX);
   void SERCOM4_0_Handler() { Serial2.IrqHandler(); }
   void SERCOM4_1_Handler() { Serial2.IrqHandler(); }
   void SERCOM4_3_Handler() { Serial2.IrqHandler(); }
 #endif
 
-#if SERIAL_PORT == 2 || SERIAL_PORT_2 == 2
+#if USING_SERIAL_2
   Uart Serial3(&sercom1, PIN_SERIAL3_RX, PIN_SERIAL3_TX, PAD_SERIAL3_RX, PAD_SERIAL3_TX);
   void SERCOM1_0_Handler() { Serial3.IrqHandler(); }
   void SERCOM1_1_Handler() { Serial3.IrqHandler(); }
   void SERCOM1_3_Handler() { Serial3.IrqHandler(); }
 #endif
 
-#if SERIAL_PORT == 3 || SERIAL_PORT_2 == 3
+#if USING_SERIAL_3
   Uart Serial4(&sercom5, PIN_SERIAL4_RX, PIN_SERIAL4_TX, PAD_SERIAL4_RX, PAD_SERIAL4_TX);
   void SERCOM5_0_Handler() { Serial4.IrqHandler(); }
   void SERCOM5_1_Handler() { Serial4.IrqHandler(); }

Marlin/src/HAL/STM32/HAL.h

   #endif
 #endif
 
+#ifdef MMU2_SERIAL_PORT
+  #if MMU2_SERIAL_PORT == -1
+    #define MMU2_SERIAL SerialUSB
+  #elif WITHIN(MMU2_SERIAL_PORT, 1, 6)
+    #define MMU2_SERIAL MSERIAL(MMU2_SERIAL_PORT)
+  #else
+    #error "MMU2_SERIAL_PORT must be -1 or from 1 to 6. Please update your configuration."
+  #endif
+#endif
+
 #ifdef LCD_SERIAL_PORT
   #if LCD_SERIAL_PORT == -1
     #define LCD_SERIAL SerialUSB

Marlin/src/HAL/STM32/MarlinSerial.cpp

   DECLARE_SERIAL_PORT_EXP(SERIAL_PORT_2)
 #endif
 
+#if defined(MMU2_SERIAL_PORT) && MMU2_SERIAL_PORT >= 0
+  DECLARE_SERIAL_PORT_EXP(MMU2_SERIAL_PORT)
+#endif
+
 #if defined(LCD_SERIAL_PORT) && LCD_SERIAL_PORT >= 0
   DECLARE_SERIAL_PORT_EXP(LCD_SERIAL_PORT)
 #endif

Marlin/src/HAL/STM32F1/HAL.h

   #endif
 #endif
 
+#ifdef MMU2_SERIAL_PORT
+  #if MMU2_SERIAL_PORT == -1
+    #define MMU2_SERIAL UsbSerial
+  #elif WITHIN(MMU2_SERIAL_PORT, 1, NUM_UARTS)
+    #define MMU2_SERIAL MSERIAL(MMU2_SERIAL_PORT)
+  #elif NUM_UARTS == 5
+    #error "MMU2_SERIAL_PORT must be -1 or from 1 to 5. Please update your configuration."
+  #else
+    #error "MMU2_SERIAL_PORT must be -1 or from 1 to 3. Please update your configuration."
+  #endif
+#endif
+
 #ifdef LCD_SERIAL_PORT
   #if LCD_SERIAL_PORT == -1
     #define LCD_SERIAL UsbSerial

Marlin/src/feature/mmu/mmu2.cpp

 #define MMU2_NO_TOOL 99
 #define MMU_BAUD    115200
 
-#define mmuSerial   MMU2_SERIAL
-
 bool MMU2::enabled, MMU2::ready, MMU2::mmu_print_saved;
 #if HAS_PRUSA_MMU2S
   bool MMU2::mmu2s_triggered;
     SET_OUTPUT(MMU2_RST_PIN);
   #endif
 
-  mmuSerial.begin(MMU_BAUD);
+  MMU2_SERIAL.begin(MMU_BAUD);
   extruder = MMU2_NO_TOOL;
 
   safe_delay(10);
 bool MMU2::rx_str_P(const char* str) {
   uint8_t i = strlen(rx_buffer);
 
-  while (mmuSerial.available()) {
-    rx_buffer[i++] = mmuSerial.read();
+  while (MMU2_SERIAL.available()) {
+    rx_buffer[i++] = MMU2_SERIAL.read();
     rx_buffer[i] = '\0';
 
     if (i == sizeof(rx_buffer) - 1) {
 void MMU2::tx_str_P(const char* str) {
   clear_rx_buffer();
   uint8_t len = strlen_P(str);
-  LOOP_L_N(i, len) mmuSerial.write(pgm_read_byte(str++));
+  LOOP_L_N(i, len) MMU2_SERIAL.write(pgm_read_byte(str++));
   rx_buffer[0] = '\0';
   prev_request = millis();
 }
 void MMU2::tx_printf_P(const char* format, int argument = -1) {
   clear_rx_buffer();
   uint8_t len = sprintf_P(tx_buffer, format, argument);
-  LOOP_L_N(i, len) mmuSerial.write(tx_buffer[i]);
+  LOOP_L_N(i, len) MMU2_SERIAL.write(tx_buffer[i]);
   rx_buffer[0] = '\0';
   prev_request = millis();
 }
 void MMU2::tx_printf_P(const char* format, int argument1, int argument2) {
   clear_rx_buffer();
   uint8_t len = sprintf_P(tx_buffer, format, argument1, argument2);
-  LOOP_L_N(i, len) mmuSerial.write(tx_buffer[i]);
+  LOOP_L_N(i, len) MMU2_SERIAL.write(tx_buffer[i]);
   rx_buffer[0] = '\0';
   prev_request = millis();
 }
  * Empty the rx buffer
  */
 void MMU2::clear_rx_buffer() {
-  while (mmuSerial.available()) mmuSerial.read();
+  while (MMU2_SERIAL.available()) MMU2_SERIAL.read();
   rx_buffer[0] = '\0';
 }
 

Marlin/src/inc/Conditionals_adv.h

 #endif
 
 // Flag the indexed serial ports that are in use
-#define ANY_SERIAL_IS(N) (defined(SERIAL_PORT) && SERIAL_PORT == (N)) || (defined(SERIAL_PORT_2) && SERIAL_PORT_2 == (N)) || (defined(LCD_SERIAL_PORT) && LCD_SERIAL_PORT == (N))
+#define ANY_SERIAL_IS(N) (defined(SERIAL_PORT) && SERIAL_PORT == (N)) || \
+                         (defined(SERIAL_PORT_2) && SERIAL_PORT_2 == (N)) || \
+                         (defined(MMU2_SERIAL_PORT) && MMU2_SERIAL_PORT == (N)) || \
+                         (defined(LCD_SERIAL_PORT) && LCD_SERIAL_PORT == (N))
 #if ANY_SERIAL_IS(-1)
   #define USING_SERIAL_DEFAULT
 #endif

Marlin/src/inc/SanityCheck.h

   #error "SERIAL_PORT must be defined."
 #elif defined(SERIAL_PORT_2) && SERIAL_PORT_2 == SERIAL_PORT
   #error "SERIAL_PORT_2 cannot be the same as SERIAL_PORT."
-#elif defined(LCD_SERIAL_PORT) && LCD_SERIAL_PORT == SERIAL_PORT
-  #error "LCD_SERIAL_PORT cannot be the same as SERIAL_PORT."
-#elif defined(LCD_SERIAL_PORT) && LCD_SERIAL_PORT == SERIAL_PORT_2
-  #error "LCD_SERIAL_PORT cannot be the same as SERIAL_PORT_2."
 #endif
 #if !(defined(__AVR__) && defined(USBCON))
   #if ENABLED(SERIAL_XON_XOFF) && RX_BUFFER_SIZE < 1024
     #error "SERIAL_PORT is set to -1, but the MOTHERBOARD has no native USB support. Set SERIAL_PORT to a valid value for your board."
   #elif SERIAL_PORT_2 == -1
     #error "SERIAL_PORT_2 is set to -1, but the MOTHERBOARD has no native USB support. Set SERIAL_PORT_2 to a valid value for your board."
+  #elif MMU2_SERIAL_PORT == -1
+    #error "MMU2_SERIAL_PORT is set to -1, but the MOTHERBOARD has no native USB support. Set MMU2_SERIAL_PORT to a valid value for your board."
   #elif LCD_SERIAL_PORT == -1
     #error "LCD_SERIAL_PORT is set to -1, but the MOTHERBOARD has no native USB support. Set LCD_SERIAL_PORT to a valid value for your board."
   #endif
 #endif
 
 /**
+ * MMU2 require a dedicated serial port
+ */
+#ifdef MMU2_SERIAL_PORT
+  #if MMU2_SERIAL_PORT == SERIAL_PORT
+    #error "MMU2_SERIAL_PORT cannot be the same as SERIAL_PORT."
+  #elif defined(SERIAL_PORT_2) && MMU2_SERIAL_PORT == SERIAL_PORT_2
+    #error "MMU2_SERIAL_PORT cannot be the same as SERIAL_PORT_2."
+  #elif defined(LCD_SERIAL_PORT) && MMU2_SERIAL_PORT == LCD_SERIAL_PORT
+    #error "MMU2_SERIAL_PORT cannot be the same as LCD_SERIAL_PORT."
+  #endif
+#endif
+
+/**
  * Serial displays require a dedicated serial port
  */
 #ifdef LCD_SERIAL_PORT