Add 4th extruder

Marlin/Configuration.h

 // The following define selects which electronics board you have.
 // Please choose the name from boards.h that matches your setup
 #ifndef MOTHERBOARD
-  #define MOTHERBOARD BOARD_ULTIMAKER
+  #define MOTHERBOARD BOARD_AZTEEG_X3_PRO
 #endif
 
 // Define this to set a custom name for your generic Mendel,
 // 147 is Pt100 with 4k7 pullup
 // 110 is Pt100 with 1k pullup (non standard)
 
-#define TEMP_SENSOR_0 -1
-#define TEMP_SENSOR_1 -1
+#define TEMP_SENSOR_0 1
+#define TEMP_SENSOR_1 0
 #define TEMP_SENSOR_2 0
+#define TEMP_SENSOR_3 0
 #define TEMP_SENSOR_BED 0
 
 // This makes temp sensor 1 a redundant sensor for sensor 0. If the temperatures difference between these sensors is to high the print will be aborted.
 // The minimal temperature defines the temperature below which the heater will not be enabled It is used
 // to check that the wiring to the thermistor is not broken.
 // Otherwise this would lead to the heater being powered on all the time.
-#define HEATER_0_MINTEMP 5
-#define HEATER_1_MINTEMP 5
-#define HEATER_2_MINTEMP 5
-#define BED_MINTEMP 5
+#define HEATER_0_MINTEMP 5 // degC
+#define HEATER_1_MINTEMP 5 // degC
+#define HEATER_2_MINTEMP 5 // degC
+#define HEATER_3_MINTEMP 5 // degC
+#define BED_MINTEMP      5 // degC
 
 // When temperature exceeds max temp, your heater will be switched off.
 // This feature exists to protect your hotend from overheating accidentally, but *NOT* from thermistor short/failure!
 // You should use MINTEMP for thermistor short/failure protection.
-#define HEATER_0_MAXTEMP 275
-#define HEATER_1_MAXTEMP 275
-#define HEATER_2_MAXTEMP 275
-#define BED_MAXTEMP 150
+#define HEATER_0_MAXTEMP 275 // degC
+#define HEATER_1_MAXTEMP 275 // degC
+#define HEATER_2_MAXTEMP 275 // degC
+#define HEATER_3_MAXTEMP 275 // degC
+#define BED_MAXTEMP      150 // degC
 
-// If your bed has low resistance e.g. .6 ohm and throws the fuse you can duty cycle it to reduce the
+// If your bed has low resistance e.g. 0.6 ohm and throws the fuse you can duty cycle it to reduce the
 // average current. The value should be an integer and the heat bed will be turned on for 1 interval of
 // HEATER_BED_DUTY_CYCLE_DIVIDER intervals.
 //#define HEATER_BED_DUTY_CYCLE_DIVIDER 4
 //if PREVENT_DANGEROUS_EXTRUDE is on, you can still disable (uncomment) very long bits of extrusion separately.
 #define PREVENT_LENGTHY_EXTRUDE
 
-#define EXTRUDE_MINTEMP 170
+#define EXTRUDE_MINTEMP 170 // degC
 #define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH) //prevent extrusion of very large distances.
 
 /*================== Thermal Runaway Protection ==============================
 #define INVERT_E0_DIR false   // for direct drive extruder v9 set to true, for geared extruder set to false
 #define INVERT_E1_DIR false    // for direct drive extruder v9 set to true, for geared extruder set to false
 #define INVERT_E2_DIR false   // for direct drive extruder v9 set to true, for geared extruder set to false
+#define INVERT_E3_DIR false   // for direct drive extruder v9 set to true, for geared extruder set to false
 
 // ENDSTOP SETTINGS:
 // Sets direction of endstops when homing; 1=MAX, -1=MIN

Marlin/ConfigurationStore.cpp

   EEPROM_WRITE_VAR(i,zprobe_zoffset);
   #ifdef PIDTEMP
     float dummy = 0.0f;
-    for (int e = 0; e < 3; e++)
+    for (int e = 0; e < 4; e++)
 	{
 	  if (e < EXTRUDERS)
 	  {
   // Save filament sizes
   EEPROM_WRITE_VAR(i, volumetric_enabled);
   EEPROM_WRITE_VAR(i, filament_size[0]);
-  #if EXTRUDERS > 1
+#if EXTRUDERS > 1
   EEPROM_WRITE_VAR(i, filament_size[1]);
-  #if EXTRUDERS > 2
+#if EXTRUDERS > 2
   EEPROM_WRITE_VAR(i, filament_size[2]);
-  #endif//EXTRUDERS > 2
-  #endif//EXTRUDERS > 1
+#if EXTRUDERS > 3
+  EEPROM_WRITE_VAR(i, filament_size[3]);
+#endif //EXTRUDERS > 3
+#endif //EXTRUDERS > 2
+#endif //EXTRUDERS > 1
   
   char ver2[4]=EEPROM_VERSION;
   i=EEPROM_OFFSET;
 		SERIAL_ECHO_START;
         SERIAL_ECHOPAIR("   M200 T2 D", filament_size[2]);
 		SERIAL_ECHOLN("");
-#endif//EXTRUDERS > 2
-#endif//EXTRUDERS > 1
+#if EXTRUDERS > 3
+        SERIAL_ECHO_START;
+        SERIAL_ECHOPAIR("   M200 T3 D", filament_size[3]);
+        SERIAL_ECHOLN("");
+#endif //EXTRUDERS > 3
+#endif //EXTRUDERS > 2
+#endif //EXTRUDERS > 1
     } else {
         SERIAL_ECHOLNPGM("Filament settings: Disabled");
     }
         EEPROM_READ_VAR(i,zprobe_zoffset);
         #ifdef PIDTEMP
 		float dummy = 0.0f;
-		for (int e = 0; e < 3; e++) // 3 = max extruders supported by marlin
+		for (int e = 0; e < 4; e++) // 4 = max extruders supported by marlin
 		{
 		  if (e < EXTRUDERS)
 		  {
 		EEPROM_READ_VAR(i, filament_size[1]);
 #if EXTRUDERS > 2
 		EEPROM_READ_VAR(i, filament_size[2]);
-#endif//EXTRUDERS > 2
-#endif//EXTRUDERS > 1
+#if EXTRUDERS > 3
+    EEPROM_READ_VAR(i, filament_size[3]);
+#endif //EXTRUDERS > 3
+#endif //EXTRUDERS > 2
+#endif //EXTRUDERS > 1
 		calculate_volumetric_multipliers();
 		// Call updatePID (similar to when we have processed M301)
 		updatePID();
 	filament_size[1] = DEFAULT_NOMINAL_FILAMENT_DIA;
 #if EXTRUDERS > 2
 	filament_size[2] = DEFAULT_NOMINAL_FILAMENT_DIA;
-#endif//EXTRUDERS > 2
-#endif//EXTRUDERS > 1
+#if EXTRUDERS > 3
+  filament_size[3] = DEFAULT_NOMINAL_FILAMENT_DIA;
+#endif //EXTRUDERS > 3
+#endif //EXTRUDERS > 2
+#endif //EXTRUDERS > 1
 	calculate_volumetric_multipliers();
 
 SERIAL_ECHO_START;

Marlin/Configuration_adv.h

 // extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
 // Multiple extruders can be assigned to the same pin in which case
 // the fan will turn on when any selected extruder is above the threshold.
-#define EXTRUDER_0_AUTO_FAN_PIN   -1
-#define EXTRUDER_1_AUTO_FAN_PIN   -1
-#define EXTRUDER_2_AUTO_FAN_PIN   -1
+#define EXTRUDER_0_AUTO_FAN_PIN -1
+#define EXTRUDER_1_AUTO_FAN_PIN -1
+#define EXTRUDER_2_AUTO_FAN_PIN -1
+#define EXTRUDER_3_AUTO_FAN_PIN -1
 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
 #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed
 
   #define THERMISTORHEATER_2 TEMP_SENSOR_2
   #define HEATER_2_USES_THERMISTOR
 #endif
+#if TEMP_SENSOR_3 > 0
+  #define THERMISTORHEATER_3 TEMP_SENSOR_3
+  #define HEATER_3_USES_THERMISTOR
+#endif
 #if TEMP_SENSOR_BED > 0
   #define THERMISTORBED TEMP_SENSOR_BED
   #define BED_USES_THERMISTOR
 #if TEMP_SENSOR_2 == -1
   #define HEATER_2_USES_AD595
 #endif
+#if TEMP_SENSOR_3 == -1
+  #define HEATER_3_USES_AD595
+#endif
 #if TEMP_SENSOR_BED == -1
   #define BED_USES_AD595
 #endif
   #undef HEATER_2_MINTEMP
   #undef HEATER_2_MAXTEMP
 #endif
+#if TEMP_SENSOR_3 == 0
+  #undef HEATER_3_MINTEMP
+  #undef HEATER_3_MAXTEMP
+#endif
 #if TEMP_SENSOR_BED == 0
   #undef BED_MINTEMP
   #undef BED_MAXTEMP

Marlin/Marlin.h

   #define disable_e2() /* nothing */
 #endif
 
+#if (EXTRUDERS > 3) && defined(E3_ENABLE_PIN) && (E3_ENABLE_PIN > -1)
+  #define enable_e3() WRITE(E3_ENABLE_PIN, E_ENABLE_ON)
+  #define disable_e3() WRITE(E3_ENABLE_PIN,!E_ENABLE_ON)
+#else
+  #define enable_e3()  /* nothing */
+  #define disable_e3() /* nothing */
+#endif
 
 enum AxisEnum {X_AXIS=0, Y_AXIS=1, Z_AXIS=2, E_AXIS=3, X_HEAD=4, Y_HEAD=5};
 

Marlin/Marlin_main.cpp

     , 100
     #if EXTRUDERS > 2
       , 100
+	    #if EXTRUDERS > 3
+      	, 100
+	    #endif
     #endif
   #endif
 };
       , DEFAULT_NOMINAL_FILAMENT_DIA
     #if EXTRUDERS > 2
        , DEFAULT_NOMINAL_FILAMENT_DIA
+      #if EXTRUDERS > 3
+        , DEFAULT_NOMINAL_FILAMENT_DIA
+      #endif
     #endif
   #endif
 };
     , 1.0
     #if EXTRUDERS > 2
       , 1.0
+      #if EXTRUDERS > 3
+        , 1.0
+      #endif
     #endif
   #endif
 };
   bool autoretract_enabled=false;
   bool retracted[EXTRUDERS]={false
     #if EXTRUDERS > 1
-    , false
-     #if EXTRUDERS > 2
       , false
-     #endif
-  #endif
+      #if EXTRUDERS > 2
+        , false
+        #if EXTRUDERS > 3
+       	  , false
+      	#endif
+      #endif
+    #endif
   };
   bool retracted_swap[EXTRUDERS]={false
     #if EXTRUDERS > 1
-    , false
-     #if EXTRUDERS > 2
       , false
-     #endif
-  #endif
+      #if EXTRUDERS > 2
+        , false
+        #if EXTRUDERS > 3
+       	  , false
+      	#endif
+      #endif
+    #endif
   };
 
   float retract_length = RETRACT_LENGTH;
   float retract_recover_length = RETRACT_RECOVER_LENGTH;
   float retract_recover_length_swap = RETRACT_RECOVER_LENGTH_SWAP;
   float retract_recover_feedrate = RETRACT_RECOVER_FEEDRATE;
-#endif
+#endif // FWRETRACT
 
 #ifdef ULTIPANEL
   #ifdef PS_DEFAULT_OFF
       SERIAL_ECHOLNPGM(STRING_CONFIG_H_AUTHOR);
       SERIAL_ECHOPGM("Compiled: ");
       SERIAL_ECHOLNPGM(__DATE__);
-    #endif
-  #endif
+    #endif // STRING_CONFIG_H_AUTHOR
+  #endif // STRING_VERSION_CONFIG_H
   SERIAL_ECHO_START;
   SERIAL_ECHOPGM(MSG_FREE_MEMORY);
   SERIAL_ECHO(freeMemory());
 
         float area = .0;
         if(code_seen('D')) {
-		  float diameter = (float)code_value();
-		  if (diameter == 0.0) {
-			// setting any extruder filament size disables volumetric on the assumption that
-			// slicers either generate in extruder values as cubic mm or as as filament feeds
-			// for all extruders
-		    volumetric_enabled = false;
-		  } else {
+          float diameter = (float)code_value();
+          if (diameter == 0.0) {
+            // setting any extruder filament size disables volumetric on the assumption that
+            // slicers either generate in extruder values as cubic mm or as as filament feeds
+            // for all extruders
+            volumetric_enabled = false;
+          } else {
             filament_size[tmp_extruder] = (float)code_value();
-			// make sure all extruders have some sane value for the filament size
-			filament_size[0] = (filament_size[0] == 0.0 ? DEFAULT_NOMINAL_FILAMENT_DIA : filament_size[0]);
-            #if EXTRUDERS > 1
-			filament_size[1] = (filament_size[1] == 0.0 ? DEFAULT_NOMINAL_FILAMENT_DIA : filament_size[1]);
-            #if EXTRUDERS > 2
-			filament_size[2] = (filament_size[2] == 0.0 ? DEFAULT_NOMINAL_FILAMENT_DIA : filament_size[2]);
-            #endif
-            #endif
-			volumetric_enabled = true;
-		  }
+            // make sure all extruders have some sane value for the filament size
+            filament_size[0] = (filament_size[0] == 0.0 ? DEFAULT_NOMINAL_FILAMENT_DIA : filament_size[0]);
+#if EXTRUDERS > 1
+            filament_size[1] = (filament_size[1] == 0.0 ? DEFAULT_NOMINAL_FILAMENT_DIA : filament_size[1]);
+#if EXTRUDERS > 2
+            filament_size[2] = (filament_size[2] == 0.0 ? DEFAULT_NOMINAL_FILAMENT_DIA : filament_size[2]);
+#if EXTRUDERS > 3
+            filament_size[3] = (filament_size[3] == 0.0 ? DEFAULT_NOMINAL_FILAMENT_DIA : filament_size[3]);
+#endif //EXTRUDERS > 3
+#endif //EXTRUDERS > 2
+#endif //EXTRUDERS > 1
+            volumetric_enabled = true;
+          }
         } else {
           //reserved for setting filament diameter via UFID or filament measuring device
           break;
         }
-		calculate_volumetric_multipliers();
+        calculate_volumetric_multipliers();
       }
       break;
     case 201: // M201
           {
             autoretract_enabled=false;
             retracted[0]=false;
-            #if EXTRUDERS > 1
-              retracted[1]=false;
-            #endif
-            #if EXTRUDERS > 2
-              retracted[2]=false;
-            #endif
+#if EXTRUDERS > 1
+            retracted[1]=false;
+#endif
+#if EXTRUDERS > 2
+            retracted[2]=false;
+#endif
+#if EXTRUDERS > 3
+            retracted[3]=false;
+#endif
           }break;
           case 1: 
           {
             autoretract_enabled=true;
             retracted[0]=false;
-            #if EXTRUDERS > 1
-              retracted[1]=false;
-            #endif
-            #if EXTRUDERS > 2
-              retracted[2]=false;
-            #endif
+#if EXTRUDERS > 1
+            retracted[1]=false;
+#endif
+#if EXTRUDERS > 2
+            retracted[2]=false;
+#endif
+#if EXTRUDERS > 3
+            retracted[3]=false;
+#endif
           }break;
           default:
             SERIAL_ECHO_START;
 	volumetric_multiplier[1] = calculate_volumetric_multiplier(filament_size[1]);
 #if EXTRUDERS > 2
 	volumetric_multiplier[2] = calculate_volumetric_multiplier(filament_size[2]);
-#endif
-#endif
+#if EXTRUDERS > 3
+	volumetric_multiplier[3] = calculate_volumetric_multiplier(filament_size[3]);
+#endif //EXTRUDERS > 3
+#endif //EXTRUDERS > 2
+#endif //EXTRUDERS > 1
 }
 

Marlin/language_en.h

 #define MSG_PREHEAT_PLA0                    "Preheat PLA 1"
 #define MSG_PREHEAT_PLA1                    "Preheat PLA 2"
 #define MSG_PREHEAT_PLA2                    "Preheat PLA 3"
-#define MSG_PREHEAT_PLA012                  "Preheat PLA All"
+#define MSG_PREHEAT_PLA3                    "Preheat PLA 4"
+#define MSG_PREHEAT_PLA0123                 "Preheat PLA All"
 #define MSG_PREHEAT_PLA_BEDONLY             "Preheat PLA Bed"
 #define MSG_PREHEAT_PLA_SETTINGS            "Preheat PLA conf"
 #define MSG_PREHEAT_ABS                     "Preheat ABS"
 #define MSG_PREHEAT_ABS0                    "Preheat ABS 1"
 #define MSG_PREHEAT_ABS1                    "Preheat ABS 2"
 #define MSG_PREHEAT_ABS2                    "Preheat ABS 3"
-#define MSG_PREHEAT_ABS012                  "Preheat ABS All"
+#define MSG_PREHEAT_ABS3                    "Preheat ABS 4"
+#define MSG_PREHEAT_ABS0123                 "Preheat ABS All"
 #define MSG_PREHEAT_ABS_BEDONLY             "Preheat ABS Bed"
 #define MSG_PREHEAT_ABS_SETTINGS            "Preheat ABS conf"
 #define MSG_COOLDOWN                        "Cooldown"
 #define MSG_MOVE_E                          "Extruder"
 #define MSG_MOVE_E1                         "Extruder2"
 #define MSG_MOVE_E2                         "Extruder3"
+#define MSG_MOVE_E3                         "Extruder4"
 #define MSG_MOVE_01MM                       "Move 0.1mm"
 #define MSG_MOVE_1MM                        "Move 1mm"
 #define MSG_MOVE_10MM                       "Move 10mm"
 #define MSG_NOZZLE                          "Nozzle"
 #define MSG_NOZZLE1                         "Nozzle2"
 #define MSG_NOZZLE2                         "Nozzle3"
+#define MSG_NOZZLE3                         "Nozzle4"
 #define MSG_BED                             "Bed"
 #define MSG_FAN_SPEED                       "Fan speed"
 #define MSG_FLOW                            "Flow"
 #define MSG_FLOW0                           "Flow 0"
 #define MSG_FLOW1                           "Flow 1"
 #define MSG_FLOW2                           "Flow 2"
+#define MSG_FLOW3                           "Flow 3"
 #define MSG_CONTROL                         "Control"
 #define MSG_MIN                             " \002 Min"
 #define MSG_MAX                             " \002 Max"
 #define MSG_PID_I2                          "PID-I E3"
 #define MSG_PID_D2                          "PID-D E3"
 #define MSG_PID_C2                          "PID-C E3"
+#define MSG_PID_P3                          "PID-P E4"
+#define MSG_PID_I3                          "PID-I E4"
+#define MSG_PID_D3                          "PID-D E4"
+#define MSG_PID_C3                          "PID-C E4"
 #define MSG_ACC                             "Accel"
 #define MSG_VXY_JERK                        "Vxy-jerk"
 #define MSG_VZ_JERK                         "Vz-jerk"
 #define MSG_FILAMENT_SIZE_EXTRUDER_0        "Fil. Dia. 1"
 #define MSG_FILAMENT_SIZE_EXTRUDER_1        "Fil. Dia. 2"
 #define MSG_FILAMENT_SIZE_EXTRUDER_2        "Fil. Dia. 3"
+#define MSG_FILAMENT_SIZE_EXTRUDER_3        "Fil. Dia. 4"
 #define MSG_CONTRAST                        "LCD contrast"
 #define MSG_STORE_EPROM                     "Store memory"
 #define MSG_LOAD_EPROM                      "Load memory"

Marlin/language_it.h

 #define MSG_PREHEAT_PLA0                    "Preriscalda PLA 1"
 #define MSG_PREHEAT_PLA1                    "Preriscalda PLA 2"
 #define MSG_PREHEAT_PLA2                    "Preriscalda PLA 3"
-#define MSG_PREHEAT_PLA012                  "Prer. PLA Tutto"
+#define MSG_PREHEAT_PLA3                    "Preriscalda PLA 4"
+#define MSG_PREHEAT_PLA0123                 "Prer. PLA Tutto"
 #define MSG_PREHEAT_PLA_BEDONLY             "Prer. PLA Piatto"
 #define MSG_PREHEAT_PLA_SETTINGS            "Config. prer. PLA"
 #define MSG_PREHEAT_ABS                     "Preriscalda ABS"
 #define MSG_PREHEAT_ABS0                    "Preriscalda ABS 1"
 #define MSG_PREHEAT_ABS1                    "Preriscalda ABS 2"
 #define MSG_PREHEAT_ABS2                    "Preriscalda ABS 3"
-#define MSG_PREHEAT_ABS012                  "Prer. ABS Tutto"
+#define MSG_PREHEAT_ABS3                    "Preriscalda ABS 4"
+#define MSG_PREHEAT_ABS0123                 "Prer. ABS Tutto"
 #define MSG_PREHEAT_ABS_BEDONLY             "Prer. ABS Piatto"
 #define MSG_PREHEAT_ABS_SETTINGS            "Config. prer. ABS"
 #define MSG_COOLDOWN                        "Raffredda"
 #define MSG_MOVE_E                          "Estrusore"
 #define MSG_MOVE_E1                         "Estrusore 2"
 #define MSG_MOVE_E2                         "Estrusore 3"
+#define MSG_MOVE_E3                         "Estrusore 4"
 #define MSG_MOVE_01MM                       "Muovi di 0.1mm"
 #define MSG_MOVE_1MM                        "Muovi di   1mm"
 #define MSG_MOVE_10MM                       "Muovi di  10mm"
 #define MSG_NOZZLE                          "Ugello"
 #define MSG_NOZZLE1                         "Ugello2"
 #define MSG_NOZZLE2                         "Ugello3"
+#define MSG_NOZZLE3                         "Ugello4"
 #define MSG_BED                             "Piatto"
 #define MSG_FAN_SPEED                       "Ventola"
 #define MSG_FLOW                            "Flusso"
 #define MSG_FLOW0                           "Flusso 0"
 #define MSG_FLOW1                           "Flusso 1"
 #define MSG_FLOW2                           "Flusso 2"
+#define MSG_FLOW3                           "Flusso 3"
 #define MSG_CONTROL                         "Controllo"
 #define MSG_MIN                             " \002 Min:"
 #define MSG_MAX                             " \002 Max:"
 #define MSG_PID_I2                          "PID-I E3"
 #define MSG_PID_D2                          "PID-D E3"
 #define MSG_PID_C2                          "PID-C E3"
+#define MSG_PID_P3                          "PID-P E4"
+#define MSG_PID_I3                          "PID-I E4"
+#define MSG_PID_D3                          "PID-D E4"
+#define MSG_PID_C3                          "PID-C E4"
 #define MSG_ACC                             "Accel."
 #define MSG_VXY_JERK                        "Vxy-jerk"
 #define MSG_VZ_JERK                         "Vz-jerk"
 #define MSG_TEMPERATURE                     "Temperatura"
 #define MSG_MOTION                          "Movimento"
 #define MSG_VOLUMETRIC                      "Filament"
-#define MSG_VOLUMETRIC_ENABLED		        "E in mm³"
+#define MSG_VOLUMETRIC_ENABLED		          "E in mm³"
 #define MSG_FILAMENT_SIZE_EXTRUDER_0        "Diam. filo 1"
 #define MSG_FILAMENT_SIZE_EXTRUDER_1        "Diam. filo 2"
 #define MSG_FILAMENT_SIZE_EXTRUDER_2        "Diam. filo 3"
+#define MSG_FILAMENT_SIZE_EXTRUDER_3        "Diam. filo 4"
 #define MSG_CONTRAST                        "Contrasto LCD"
 #define MSG_STORE_EPROM                     "Salva in EEPROM"
 #define MSG_LOAD_EPROM                      "Carica da EEPROM"

Marlin/pins.h

 #endif // CHEAPTRONIC
 
 
+#ifndef HEATER_3_PIN
+  #define HEATER_3_PIN -1
+#endif
+#ifndef TEMP_3_PIN
+  #define TEMP_3_PIN -1
+#endif
 
 #ifndef KNOWN_BOARD
 #error Unknown MOTHERBOARD value in configuration.h
 #else
   #define _E2_PINS
 #endif
+#if EXTRUDERS > 3
+  #define _E3_PINS E3_STEP_PIN, E3_DIR_PIN, E3_ENABLE_PIN, HEATER_3_PIN,
+#else
+  #define _E3_PINS
+#endif
 
 #ifdef X_STOP_PIN
   #if X_HOME_DIR < 0
 
 #define SENSITIVE_PINS {0, 1, X_STEP_PIN, X_DIR_PIN, X_ENABLE_PIN, X_MIN_PIN, X_MAX_PIN, Y_STEP_PIN, Y_DIR_PIN, Y_ENABLE_PIN, Y_MIN_PIN, Y_MAX_PIN, Z_STEP_PIN, Z_DIR_PIN, Z_ENABLE_PIN, Z_MIN_PIN, Z_MAX_PIN, PS_ON_PIN, \
                         HEATER_BED_PIN, FAN_PIN,                  \
-                        _E0_PINS _E1_PINS _E2_PINS             \
-                        analogInputToDigitalPin(TEMP_0_PIN), analogInputToDigitalPin(TEMP_1_PIN), analogInputToDigitalPin(TEMP_2_PIN), analogInputToDigitalPin(TEMP_BED_PIN) }
-
+                        _E0_PINS _E1_PINS _E2_PINS _E3_PINS           \
+                        analogInputToDigitalPin(TEMP_0_PIN), analogInputToDigitalPin(TEMP_1_PIN), analogInputToDigitalPin(TEMP_2_PIN), analogInputToDigitalPin(TEMP_3_PIN), analogInputToDigitalPin(TEMP_BED_PIN) }
 #endif //__PINS_H

Marlin/planner.cpp

 matrix_3x3 plan_bed_level_matrix = {
 	1.0, 0.0, 0.0,
 	0.0, 1.0, 0.0,
-	0.0, 0.0, 1.0,
+	0.0, 0.0, 1.0
 };
 #endif // #ifdef ENABLE_AUTO_BED_LEVELING
 
 bool autotemp_enabled=false;
 #endif
 
-unsigned char g_uc_extruder_last_move[3] = {0,0,0};
+unsigned char g_uc_extruder_last_move[4] = {0,0,0,0};
 
 //===========================================================================
 //=================semi-private variables, used in inline  functions    =====
     disable_e0();
     disable_e1();
     disable_e2(); 
+    disable_e3();
   }
 #if defined(FAN_PIN) && FAN_PIN > -1
   #ifdef FAN_KICKSTART_TIME
       if(g_uc_extruder_last_move[0] > 0) g_uc_extruder_last_move[0]--;
       if(g_uc_extruder_last_move[1] > 0) g_uc_extruder_last_move[1]--;
       if(g_uc_extruder_last_move[2] > 0) g_uc_extruder_last_move[2]--;
+      if(g_uc_extruder_last_move[3] > 0) g_uc_extruder_last_move[3]--;
       
       switch(extruder)
       {
           
           if(g_uc_extruder_last_move[1] == 0) disable_e1(); 
           if(g_uc_extruder_last_move[2] == 0) disable_e2(); 
+          if(g_uc_extruder_last_move[3] == 0) disable_e3(); 
         break;
         case 1:
           enable_e1(); 
           
           if(g_uc_extruder_last_move[0] == 0) disable_e0(); 
           if(g_uc_extruder_last_move[2] == 0) disable_e2(); 
+          if(g_uc_extruder_last_move[3] == 0) disable_e3(); 
         break;
         case 2:
           enable_e2(); 
           
           if(g_uc_extruder_last_move[0] == 0) disable_e0(); 
           if(g_uc_extruder_last_move[1] == 0) disable_e1(); 
+          if(g_uc_extruder_last_move[3] == 0) disable_e3(); 
+        break;        
+        case 3:
+          enable_e3(); 
+          g_uc_extruder_last_move[3] = BLOCK_BUFFER_SIZE*2;
+          
+          if(g_uc_extruder_last_move[0] == 0) disable_e0(); 
+          if(g_uc_extruder_last_move[1] == 0) disable_e1(); 
+          if(g_uc_extruder_last_move[2] == 0) disable_e2(); 
         break;        
       }
     }
     {
       enable_e0();
       enable_e1();
-      enable_e2(); 
+      enable_e2();
+      enable_e3();
     }
   }
 
   long min_xy_segment_time =min(max_x_segment_time, max_y_segment_time);
   if(min_xy_segment_time < MAX_FREQ_TIME)
     speed_factor = min(speed_factor, speed_factor * (float)min_xy_segment_time / (float)MAX_FREQ_TIME);
-#endif
+#endif // XY_FREQUENCY_LIMIT
 
   // Correct the speed  
   if( speed_factor < 1.0)

Marlin/stepper.cpp

 #ifdef ADVANCE
   static long advance_rate, advance, final_advance = 0;
   static long old_advance = 0;
-  static long e_steps[3];
+  static long e_steps[4];
 #endif
 static long acceleration_time, deceleration_time;
 //static unsigned long accelerate_until, decelerate_after, acceleration_rate, initial_rate, final_rate, nominal_rate;
      setTargetHotend0(0);
      setTargetHotend1(0);
      setTargetHotend2(0);
+     setTargetHotend3(0);
+     setTargetBed(0);
    }
 #endif
  }
 //    SERIAL_ECHOPGM("advance rate :");
 //    SERIAL_ECHO(current_block->advance_rate/256.0);
 //    SERIAL_ECHOPGM("initial advance :");
-//  SERIAL_ECHO(current_block->initial_advance/256.0);
+//    SERIAL_ECHO(current_block->initial_advance/256.0);
 //    SERIAL_ECHOPGM("final advance :");
 //    SERIAL_ECHOLN(current_block->final_advance/256.0);
 
       }
       #endif //ADVANCE
 
-        counter_x += current_block->steps_x;
-        #ifdef CONFIG_STEPPERS_TOSHIBA
+      counter_x += current_block->steps_x;
+#ifdef CONFIG_STEPPERS_TOSHIBA
 	/* The toshiba stepper controller require much longer pulses
 	 * tjerfore we 'stage' decompose the pulses between high, and
 	 * low instead of doing each in turn. The extra tests add enough
           WRITE_E_STEP(INVERT_E_STEP_PIN);
         }
       #endif //!ADVANCE
-      #endif
+#endif // CONFIG_STEPPERS_TOSHIBA
       step_events_completed += 1;
       if(step_events_completed >= current_block->step_event_count) break;
     }
         }
       }
  #endif
+ #if EXTRUDERS > 3
+      if (e_steps[3] != 0) {
+        WRITE(E3_STEP_PIN, INVERT_E_STEP_PIN);
+        if (e_steps[3] < 0) {
+          WRITE(E3_DIR_PIN, INVERT_E3_DIR);
+          e_steps[3]++;
+          WRITE(E3_STEP_PIN, !INVERT_E_STEP_PIN);
+        }
+        else if (e_steps[3] > 0) {
+          WRITE(E3_DIR_PIN, !INVERT_E3_DIR);
+          e_steps[3]--;
+          WRITE(E3_STEP_PIN, !INVERT_E_STEP_PIN);
+        }
+      }
+ #endif
+
     }
   }
 #endif // ADVANCE
   #if defined(E2_DIR_PIN) && (E2_DIR_PIN > -1)
     SET_OUTPUT(E2_DIR_PIN);
   #endif
+  #if defined(E3_DIR_PIN) && (E3_DIR_PIN > -1)
+    SET_OUTPUT(E3_DIR_PIN);
+  #endif
 
   //Initialize Enable Pins - steppers default to disabled.
 
     SET_OUTPUT(E2_ENABLE_PIN);
     if(!E_ENABLE_ON) WRITE(E2_ENABLE_PIN,HIGH);
   #endif
+  #if defined(E3_ENABLE_PIN) && (E3_ENABLE_PIN > -1)
+    SET_OUTPUT(E3_ENABLE_PIN);
+    if(!E_ENABLE_ON) WRITE(E3_ENABLE_PIN,HIGH);
+  #endif
 
   //endstops and pullups
 
     WRITE(E2_STEP_PIN,INVERT_E_STEP_PIN);
     disable_e2();
   #endif
+  #if defined(E3_STEP_PIN) && (E3_STEP_PIN > -1)
+    SET_OUTPUT(E3_STEP_PIN);
+    WRITE(E3_STEP_PIN,INVERT_E_STEP_PIN);
+    disable_e3();
+  #endif
 
   // waveform generation = 0100 = CTC
   TCCR1B &= ~(1<<WGM13);
     e_steps[0] = 0;
     e_steps[1] = 0;
     e_steps[2] = 0;
+    e_steps[3] = 0;
     TIMSK0 |= (1<<OCIE0A);
   #endif //ADVANCE
 
   disable_e0();
   disable_e1();
   disable_e2();
+  disable_e3();
 }
 
 void quickStop()

Marlin/stepper.h

 
 #include "planner.h"
 
-#if EXTRUDERS > 2
+#if EXTRUDERS > 3
+  #define WRITE_E_STEP(v) { if(current_block->active_extruder == 3) { WRITE(E3_STEP_PIN, v); } else { if(current_block->active_extruder == 2) { WRITE(E2_STEP_PIN, v); } else { if(current_block->active_extruder == 1) { WRITE(E1_STEP_PIN, v); } else { WRITE(E0_STEP_PIN, v); }}}}
+  #define NORM_E_DIR() { if(current_block->active_extruder == 3) { WRITE(E3_DIR_PIN, !INVERT_E3_DIR); } else { if(current_block->active_extruder == 2) { WRITE(E2_DIR_PIN, !INVERT_E2_DIR); } else { if(current_block->active_extruder == 1) { WRITE(E1_DIR_PIN, !INVERT_E1_DIR); } else { WRITE(E0_DIR_PIN, !INVERT_E0_DIR); }}}}
+  #define REV_E_DIR() { if(current_block->active_extruder == 3) { WRITE(E3_DIR_PIN, INVERT_E3_DIR); } else { if(current_block->active_extruder == 2) { WRITE(E2_DIR_PIN, INVERT_E2_DIR); } else { if(current_block->active_extruder == 1) { WRITE(E1_DIR_PIN, INVERT_E1_DIR); } else { WRITE(E0_DIR_PIN, INVERT_E0_DIR); }}}}
+#elif EXTRUDERS > 2
   #define WRITE_E_STEP(v) { if(current_block->active_extruder == 2) { WRITE(E2_STEP_PIN, v); } else { if(current_block->active_extruder == 1) { WRITE(E1_STEP_PIN, v); } else { WRITE(E0_STEP_PIN, v); }}}
   #define NORM_E_DIR() { if(current_block->active_extruder == 2) { WRITE(E2_DIR_PIN, !INVERT_E2_DIR); } else { if(current_block->active_extruder == 1) { WRITE(E1_DIR_PIN, !INVERT_E1_DIR); } else { WRITE(E0_DIR_PIN, !INVERT_E0_DIR); }}}
   #define REV_E_DIR() { if(current_block->active_extruder == 2) { WRITE(E2_DIR_PIN, INVERT_E2_DIR); } else { if(current_block->active_extruder == 1) { WRITE(E1_DIR_PIN, INVERT_E1_DIR); } else { WRITE(E0_DIR_PIN, INVERT_E0_DIR); }}}

Marlin/temperature.cpp

   static unsigned long extruder_autofan_last_check;
 #endif  
 
-#if EXTRUDERS > 3
+#if EXTRUDERS > 4
   # error Unsupported number of extruders
+#elif EXTRUDERS > 3
+  # define ARRAY_BY_EXTRUDERS(v1, v2, v3, v4) { v1, v2, v3, v4 }
 #elif EXTRUDERS > 2
-  # define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1, v2, v3 }
+  # define ARRAY_BY_EXTRUDERS(v1, v2, v3, v4) { v1, v2, v3 }
 #elif EXTRUDERS > 1
-  # define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1, v2 }
+  # define ARRAY_BY_EXTRUDERS(v1, v2, v3, v4) { v1, v2 }
 #else
-  # define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1 }
+  # define ARRAY_BY_EXTRUDERS(v1, v2, v3, v4) { v1 }
 #endif
 
 #ifdef PIDTEMP
 #endif //PIDTEMP
 
 // Init min and max temp with extreme values to prevent false errors during startup
-static int minttemp_raw[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_RAW_LO_TEMP , HEATER_1_RAW_LO_TEMP , HEATER_2_RAW_LO_TEMP );
-static int maxttemp_raw[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_RAW_HI_TEMP , HEATER_1_RAW_HI_TEMP , HEATER_2_RAW_HI_TEMP );
-static int minttemp[EXTRUDERS] = ARRAY_BY_EXTRUDERS( 0, 0, 0 );
-static int maxttemp[EXTRUDERS] = ARRAY_BY_EXTRUDERS( 16383, 16383, 16383 );
+static int minttemp_raw[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_RAW_LO_TEMP , HEATER_1_RAW_LO_TEMP , HEATER_2_RAW_LO_TEMP, HEATER_3_RAW_LO_TEMP);
+static int maxttemp_raw[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_RAW_HI_TEMP , HEATER_1_RAW_HI_TEMP , HEATER_2_RAW_HI_TEMP, HEATER_3_RAW_HI_TEMP);
+static int minttemp[EXTRUDERS] = ARRAY_BY_EXTRUDERS( 0, 0, 0, 0 );
+static int maxttemp[EXTRUDERS] = ARRAY_BY_EXTRUDERS( 16383, 16383, 16383, 16383 );
 //static int bed_minttemp_raw = HEATER_BED_RAW_LO_TEMP; /* No bed mintemp error implemented?!? */
 #ifdef BED_MAXTEMP
 static int bed_maxttemp_raw = HEATER_BED_RAW_HI_TEMP;
   static void *heater_ttbl_map[2] = {(void *)HEATER_0_TEMPTABLE, (void *)HEATER_1_TEMPTABLE };
   static uint8_t heater_ttbllen_map[2] = { HEATER_0_TEMPTABLE_LEN, HEATER_1_TEMPTABLE_LEN };
 #else
-  static void *heater_ttbl_map[EXTRUDERS] = ARRAY_BY_EXTRUDERS( (void *)HEATER_0_TEMPTABLE, (void *)HEATER_1_TEMPTABLE, (void *)HEATER_2_TEMPTABLE );
-  static uint8_t heater_ttbllen_map[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_TEMPTABLE_LEN, HEATER_1_TEMPTABLE_LEN, HEATER_2_TEMPTABLE_LEN );
+  static void *heater_ttbl_map[EXTRUDERS] = ARRAY_BY_EXTRUDERS( (void *)HEATER_0_TEMPTABLE, (void *)HEATER_1_TEMPTABLE, (void *)HEATER_2_TEMPTABLE, (void *)HEATER_3_TEMPTABLE );
+  static uint8_t heater_ttbllen_map[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_TEMPTABLE_LEN, HEATER_1_TEMPTABLE_LEN, HEATER_2_TEMPTABLE_LEN, HEATER_3_TEMPTABLE_LEN );
 #endif
 
 static float analog2temp(int raw, uint8_t e);
 static void updateTemperaturesFromRawValues();
 
 #ifdef WATCH_TEMP_PERIOD
-int watch_start_temp[EXTRUDERS] = ARRAY_BY_EXTRUDERS(0,0,0);
-unsigned long watchmillis[EXTRUDERS] = ARRAY_BY_EXTRUDERS(0,0,0);
+int watch_start_temp[EXTRUDERS] = ARRAY_BY_EXTRUDERS(0,0,0,0);
+unsigned long watchmillis[EXTRUDERS] = ARRAY_BY_EXTRUDERS(0,0,0,0);
 #endif //WATCH_TEMP_PERIOD
 
 #ifndef SOFT_PWM_SCALE
 
 #if (defined(EXTRUDER_0_AUTO_FAN_PIN) && EXTRUDER_0_AUTO_FAN_PIN > -1) || \
     (defined(EXTRUDER_1_AUTO_FAN_PIN) && EXTRUDER_1_AUTO_FAN_PIN > -1) || \
-    (defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1)
+    (defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1) || \
+    (defined(EXTRUDER_3_AUTO_FAN_PIN) && EXTRUDER_3_AUTO_FAN_PIN > -1)
   unsigned long extruder_autofan_last_check = millis();
 #endif
 
 
       #if (defined(EXTRUDER_0_AUTO_FAN_PIN) && EXTRUDER_0_AUTO_FAN_PIN > -1) || \
           (defined(EXTRUDER_1_AUTO_FAN_PIN) && EXTRUDER_1_AUTO_FAN_PIN > -1) || \
-          (defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1)
+          (defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1) || \
+          (defined(EXTRUDER_3_AUTO_FAN_PIN) && EXTRUDER_3_AUTO_FAN_PIN > -1)
       if(millis() - extruder_autofan_last_check > 2500) {
         checkExtruderAutoFans();
         extruder_autofan_last_check = millis();
         fanState |= 4;
     }
   #endif
+  #if defined(EXTRUDER_3_AUTO_FAN_PIN) && EXTRUDER_3_AUTO_FAN_PIN > -1
+    if (current_temperature[3] > EXTRUDER_AUTO_FAN_TEMPERATURE) 
+    {
+      if (EXTRUDER_3_AUTO_FAN_PIN == EXTRUDER_0_AUTO_FAN_PIN) 
+        fanState |= 1;
+      else if (EXTRUDER_3_AUTO_FAN_PIN == EXTRUDER_1_AUTO_FAN_PIN) 
+        fanState |= 2;
+      else if (EXTRUDER_3_AUTO_FAN_PIN == EXTRUDER_2_AUTO_FAN_PIN) 
+        fanState |= 4;
+      else
+        fanState |= 8;
+    }
+  #endif
   
   // update extruder auto fan states
   #if defined(EXTRUDER_0_AUTO_FAN_PIN) && EXTRUDER_0_AUTO_FAN_PIN > -1
     if (EXTRUDER_2_AUTO_FAN_PIN != EXTRUDER_0_AUTO_FAN_PIN 
         && EXTRUDER_2_AUTO_FAN_PIN != EXTRUDER_1_AUTO_FAN_PIN)
       setExtruderAutoFanState(EXTRUDER_2_AUTO_FAN_PIN, (fanState & 4) != 0);
-  #endif 
+  #endif
+  #if defined(EXTRUDER_3_AUTO_FAN_PIN) && EXTRUDER_3_AUTO_FAN_PIN > -1
+    if (EXTRUDER_3_AUTO_FAN_PIN != EXTRUDER_0_AUTO_FAN_PIN 
+        && EXTRUDER_3_AUTO_FAN_PIN != EXTRUDER_1_AUTO_FAN_PIN)
+        && EXTRUDER_3_AUTO_FAN_PIN != EXTRUDER_0_AUTO_FAN_PIN)
+      setExtruderAutoFanState(EXTRUDER_3_AUTO_FAN_PIN, (fanState & 8) != 0);
+  #endif
 }
 
 #endif // any extruder auto fan pins set
 		  temp_dState_bed = pid_input;
 
 		  pid_output = pTerm_bed + iTerm_bed - dTerm_bed;
-          	  if (pid_output > MAX_BED_POWER) {
-            	    if (pid_error_bed > 0 )  temp_iState_bed -= pid_error_bed; // conditional un-integration
-                    pid_output=MAX_BED_POWER;
-          	  } else if (pid_output < 0){
-            	    if (pid_error_bed < 0 )  temp_iState_bed -= pid_error_bed; // conditional un-integration
-                    pid_output=0;
-                  }
+      if (pid_output > MAX_BED_POWER) {
+        if (pid_error_bed > 0 )  temp_iState_bed -= pid_error_bed; // conditional un-integration
+        pid_output=MAX_BED_POWER;
+      } else if (pid_output < 0){
+        if (pid_error_bed < 0 )  temp_iState_bed -= pid_error_bed; // conditional un-integration
+        pid_output=0;
+      }
 
     #else 
       pid_output = constrain(target_temperature_bed, 0, MAX_BED_POWER);
 
   #if defined(HEATER_0_PIN) && (HEATER_0_PIN > -1) 
     SET_OUTPUT(HEATER_0_PIN);
-  #endif  
+  #endif
   #if defined(HEATER_1_PIN) && (HEATER_1_PIN > -1) 
     SET_OUTPUT(HEATER_1_PIN);
   #endif
   #if defined(HEATER_2_PIN) && (HEATER_2_PIN > -1) 
     SET_OUTPUT(HEATER_2_PIN);
-  #endif  
+  #endif
+  #if defined(HEATER_3_PIN) && (HEATER_3_PIN > -1) 
+    SET_OUTPUT(HEATER_3_PIN);
+  #endif
   #if defined(HEATER_BED_PIN) && (HEATER_BED_PIN > -1) 
     SET_OUTPUT(HEATER_BED_PIN);
   #endif  
   #endif
   #if defined(TEMP_1_PIN) && (TEMP_1_PIN > -1)
     #if TEMP_1_PIN < 8
-       DIDR0 |= 1<<TEMP_1_PIN; 
+      DIDR0 |= 1<<TEMP_1_PIN; 
     #else
-       DIDR2 |= 1<<(TEMP_1_PIN - 8); 
+    	DIDR2 |= 1<<(TEMP_1_PIN - 8); 
     #endif
   #endif
   #if defined(TEMP_2_PIN) && (TEMP_2_PIN > -1)
     #if TEMP_2_PIN < 8
-       DIDR0 |= 1 << TEMP_2_PIN; 
+      DIDR0 |= 1 << TEMP_2_PIN; 
+    #else
+      DIDR2 |= 1<<(TEMP_2_PIN - 8); 
+    #endif
+  #endif
+  #if defined(TEMP_3_PIN) && (TEMP_3_PIN > -1)
+    #if TEMP_3_PIN < 8
+      DIDR0 |= 1 << TEMP_3_PIN; 
     #else
-       DIDR2 |= 1<<(TEMP_2_PIN - 8); 
+      DIDR2 |= 1<<(TEMP_3_PIN - 8); 
     #endif
   #endif
   #if defined(TEMP_BED_PIN) && (TEMP_BED_PIN > -1)
   
   //Added for Filament Sensor 
   #ifdef FILAMENT_SENSOR
-   #if defined(FILWIDTH_PIN) && (FILWIDTH_PIN > -1) 
-	#if FILWIDTH_PIN < 8 
-       	   DIDR0 |= 1<<FILWIDTH_PIN;  
-	#else 
-       	   DIDR2 |= 1<<(FILWIDTH_PIN - 8);  
-	#endif 
-   #endif
+    #if defined(FILWIDTH_PIN) && (FILWIDTH_PIN > -1) 
+      #if FILWIDTH_PIN < 8 
+        DIDR0 |= 1<<FILWIDTH_PIN;  
+      #else
+        DIDR2 |= 1<<(FILWIDTH_PIN - 8);  
+      #endif 
+    #endif
   #endif
   
   // Use timer0 for temperature measurement
   }
 #endif //MAXTEMP 2
 
+#if (EXTRUDERS > 3) && defined(HEATER_3_MINTEMP)
+  minttemp[3] = HEATER_3_MINTEMP;
+  while(analog2temp(minttemp_raw[3], 3) < HEATER_3_MINTEMP) {
+#if HEATER_3_RAW_LO_TEMP < HEATER_3_RAW_HI_TEMP
+    minttemp_raw[3] += OVERSAMPLENR;
+#else
+    minttemp_raw[3] -= OVERSAMPLENR;
+#endif
+  }
+#endif //MINTEMP 3
+#if (EXTRUDERS > 3) && defined(HEATER_3_MAXTEMP)
+  maxttemp[3] = HEATER_3_MAXTEMP;
+  while(analog2temp(maxttemp_raw[3], 3) > HEATER_3_MAXTEMP) {
+#if HEATER_3_RAW_LO_TEMP < HEATER_3_RAW_HI_TEMP
+    maxttemp_raw[3] -= OVERSAMPLENR;
+#else
+    maxttemp_raw[3] += OVERSAMPLENR;
+#endif
+  }
+#endif // MAXTEMP 3
+
+
 #ifdef BED_MINTEMP
   /* No bed MINTEMP error implemented?!? */ /*
   while(analog2tempBed(bed_minttemp_raw) < BED_MINTEMP) {
           disable_e0();
           disable_e1();
           disable_e2();
+          disable_e3();
           manage_heater();
           lcd_update();
         }
     #if defined(HEATER_2_PIN) && HEATER_2_PIN > -1  
       WRITE(HEATER_2_PIN,LOW);
     #endif
+  #endif
+
+  #if defined(TEMP_3_PIN) && TEMP_3_PIN > -1 && EXTRUDERS > 3
+    target_temperature[3]=0;
+    soft_pwm[3]=0;
+    #if defined(HEATER_3_PIN) && HEATER_3_PIN > -1  
+      WRITE(HEATER_3_PIN,LOW);
+    #endif
   #endif 
 
+
   #if defined(TEMP_BED_PIN) && TEMP_BED_PIN > -1
     target_temperature_bed=0;
     soft_pwm_bed=0;
   static unsigned long raw_temp_0_value = 0;
   static unsigned long raw_temp_1_value = 0;
   static unsigned long raw_temp_2_value = 0;
+  static unsigned long raw_temp_3_value = 0;
   static unsigned long raw_temp_bed_value = 0;
-  static unsigned char temp_state = 10;
+  static unsigned char temp_state = 12;
   static unsigned char pwm_count = (1 << SOFT_PWM_SCALE);
   static unsigned char soft_pwm_0;
 #ifdef SLOW_PWM_HEATERS
   static unsigned char state_heater_0 = 0;
   static unsigned char state_timer_heater_0 = 0;
 #endif 
+
 #if (EXTRUDERS > 1) || defined(HEATERS_PARALLEL)
   static unsigned char soft_pwm_1;
 #ifdef SLOW_PWM_HEATERS
   static unsigned char state_timer_heater_2 = 0;
 #endif 
 #endif
+#if EXTRUDERS > 3
+  static unsigned char soft_pwm_3;
+#ifdef SLOW_PWM_HEATERS
+  static unsigned char state_heater_3 = 0;
+  static unsigned char state_timer_heater_3 = 0;
+#endif
+#endif
+
 #if HEATER_BED_PIN > -1
   static unsigned char soft_pwm_b;
 #ifdef SLOW_PWM_HEATERS
       WRITE(HEATER_1_PIN,1);
 #endif
     } else WRITE(HEATER_0_PIN,0);
-    
+
 #if EXTRUDERS > 1
     soft_pwm_1 = soft_pwm[1];
     if(soft_pwm_1 > 0) WRITE(HEATER_1_PIN,1); else WRITE(HEATER_1_PIN,0);
     soft_pwm_2 = soft_pwm[2];
     if(soft_pwm_2 > 0) WRITE(HEATER_2_PIN,1); else WRITE(HEATER_2_PIN,0);
 #endif
+#if EXTRUDERS > 3
+    soft_pwm_3 = soft_pwm[3];
+    if(soft_pwm_3 > 0) WRITE(HEATER_3_PIN,1); else WRITE(HEATER_3_PIN,0);
+#endif
+
+
 #if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
     soft_pwm_b = soft_pwm_bed;
     if(soft_pwm_b > 0) WRITE(HEATER_BED_PIN,1); else WRITE(HEATER_BED_PIN,0);
     WRITE(HEATER_1_PIN,0);
 #endif
   }
+
 #if EXTRUDERS > 1
   if(soft_pwm_1 < pwm_count) WRITE(HEATER_1_PIN,0);
 #endif
 #if EXTRUDERS > 2
   if(soft_pwm_2 < pwm_count) WRITE(HEATER_2_PIN,0);
 #endif
+#if EXTRUDERS > 3
+  if(soft_pwm_3 < pwm_count) WRITE(HEATER_3_PIN,0);
+#endif
+
 #if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
   if(soft_pwm_b < pwm_count) WRITE(HEATER_BED_PIN,0);
 #endif
       }
     }
 #endif
-    
+
+#if EXTRUDERS > 3
+    // EXTRUDER 3
+    soft_pwm_3 = soft_pwm[3];
+    if (soft_pwm_3 > 0) {
+      // turn ON heather only if the minimum time is up 
+      if (state_timer_heater_3 == 0) { 
+	// if change state set timer 
+	if (state_heater_3 == 0) {
+	  state_timer_heater_3 = MIN_STATE_TIME;
+	}
+	state_heater_3 = 1;
+	WRITE(HEATER_3_PIN, 1);
+      }
+    } else {
+      // turn OFF heather only if the minimum time is up 
+      if (state_timer_heater_3 == 0) {
+	// if change state set timer 
+	if (state_heater_3 == 1) {
+	  state_timer_heater_3 = MIN_STATE_TIME;
+	}
+	state_heater_3 = 0;
+	WRITE(HEATER_3_PIN, 0);
+      }
+    }
+#endif
+
 #if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
     // BED
     soft_pwm_b = soft_pwm_bed;
     }
   }
 #endif
+
+#if EXTRUDERS > 3
+  // EXTRUDER 3
+  if (soft_pwm_3 < slow_pwm_count) {
+    // turn OFF heather only if the minimum time is up 
+    if (state_timer_heater_3 == 0) { 
+      // if change state set timer 
+      if (state_heater_3 == 1) {
+	state_timer_heater_3 = MIN_STATE_TIME;
+      }
+      state_heater_3 = 0;
+      WRITE(HEATER_3_PIN, 0);
+    }
+  }
+#endif
   
 #if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
   // BED
     if (state_timer_heater_2 > 0) 
       state_timer_heater_2--;
 #endif
+
+#if EXTRUDERS > 3
+    // Extruder 3
+    if (state_timer_heater_3 > 0) 
+      state_timer_heater_3--;
+#endif
     
 #if defined(HEATER_BED_PIN) && HEATER_BED_PIN > -1
     // Bed   
       #if defined(TEMP_2_PIN) && (TEMP_2_PIN > -1)
         raw_temp_2_value += ADC;
       #endif
-      temp_state = 8;//change so that Filament Width is also measured
-      
+      temp_state = 8;
       break;
-    case 8: //Prepare FILWIDTH 
+    case 8: // Prepare TEMP_3
+      #if defined(TEMP_3_PIN) && (TEMP_3_PIN > -1)
+        #if TEMP_3_PIN > 7
+          ADCSRB = 1<<MUX5;
+        #else
+          ADCSRB = 0;
+        #endif
+        ADMUX = ((1 << REFS0) | (TEMP_3_PIN & 0x07));
+        ADCSRA |= 1<<ADSC; // Start conversion
+      #endif
+      lcd_buttons_update();
+      temp_state = 9;
+      break;
+    case 9: // Measure TEMP_3
+      #if defined(TEMP_3_PIN) && (TEMP_3_PIN > -1)
+        raw_temp_3_value += ADC;
+      #endif
+      temp_state = 10; //change so that Filament Width is also measured
+      break;
+    case 10: //Prepare FILWIDTH 
      #if defined(FILWIDTH_PIN) && (FILWIDTH_PIN> -1) 
       #if FILWIDTH_PIN>7 
          ADCSRB = 1<<MUX5;
       ADCSRA |= 1<<ADSC; // Start conversion 
      #endif 
      lcd_buttons_update();       
-     temp_state = 9; 
+     temp_state = 11; 
      break; 
-    case 9:   //Measure FILWIDTH 
+    case 11:   //Measure FILWIDTH 
      #if defined(FILWIDTH_PIN) &&(FILWIDTH_PIN > -1) 
      //raw_filwidth_value += ADC;  //remove to use an IIR filter approach 
       if(ADC>102)  //check that ADC is reading a voltage > 0.5 volts, otherwise don't take in the data.
      break;      
       
       
-    case 10: //Startup, delay initial temp reading a tiny bit so the hardware can settle.
+    case 12: //Startup, delay initial temp reading a tiny bit so the hardware can settle.
       temp_state = 0;
       break;
 //    default:
 #if EXTRUDERS > 2
       current_temperature_raw[2] = raw_temp_2_value;
 #endif
+#if EXTRUDERS > 3
+      current_temperature_raw[3] = raw_temp_3_value;
+#endif
       current_temperature_bed_raw = raw_temp_bed_value;
     }
 
     raw_temp_0_value = 0;
     raw_temp_1_value = 0;
     raw_temp_2_value = 0;
+    raw_temp_3_value = 0;
     raw_temp_bed_value = 0;
 
 #if HEATER_0_RAW_LO_TEMP > HEATER_0_RAW_HI_TEMP
         min_temp_error(0);
 #endif
     }
+
+
 #if EXTRUDERS > 1
 #if HEATER_1_RAW_LO_TEMP > HEATER_1_RAW_HI_TEMP
     if(current_temperature_raw[1] <= maxttemp_raw[1]) {
         min_temp_error(2);
     }
 #endif
-  
+#if EXTRUDERS > 3
+#if HEATER_3_RAW_LO_TEMP > HEATER_3_RAW_HI_TEMP
+    if(current_temperature_raw[3] <= maxttemp_raw[3]) {
+#else
+    if(current_temperature_raw[3] >= maxttemp_raw[3]) {
+#endif
+        max_temp_error(3);
+    }
+#if HEATER_3_RAW_LO_TEMP > HEATER_3_RAW_HI_TEMP
+    if(current_temperature_raw[3] >= minttemp_raw[3]) {
+#else
+    if(current_temperature_raw[3] <= minttemp_raw[3]) {
+#endif
+        min_temp_error(3);
+    }
+#endif
+
+
   /* No bed MINTEMP error? */
 #if defined(BED_MAXTEMP) && (TEMP_SENSOR_BED != 0)
 # if HEATER_BED_RAW_LO_TEMP > HEATER_BED_RAW_HI_TEMP
 }
 
 #endif //PIDTEMP
-
-

Marlin/temperature.h

 #define setTargetHotend2(_celsius) do{}while(0)
 #endif
 #if EXTRUDERS > 3
+#define degHotend3() degHotend(3)
+#define degTargetHotend3() degTargetHotend(3)
+#define setTargetHotend3(_celsius) setTargetHotend((_celsius), 3)
+#define isHeatingHotend3() isHeatingHotend(3)
+#define isCoolingHotend3() isCoolingHotend(3)
+#else
+#define setTargetHotend3(_celsius) do{}while(0)
+#endif
+#if EXTRUDERS > 4
 #error Invalid number of extruders
 #endif
 
 
 #if defined (THERMAL_RUNAWAY_PROTECTION_PERIOD) && THERMAL_RUNAWAY_PROTECTION_PERIOD > 0
 void thermal_runaway_protection(int *state, unsigned long *timer, float temperature, float target_temperature, int heater_id, int period_seconds, int hysteresis_degc);
-static int thermal_runaway_state_machine[3]; // = {0,0,0};
-static unsigned long thermal_runaway_timer[3]; // = {0,0,0};
+static int thermal_runaway_state_machine[4]; // = {0,0,0,0};
+static unsigned long thermal_runaway_timer[4]; // = {0,0,0,0};
 static bool thermal_runaway = false;
-  #if TEMP_SENSOR_BED != 0
-    static int thermal_runaway_bed_state_machine;
-    static unsigned long thermal_runaway_bed_timer;
-  #endif
+#if TEMP_SENSOR_BED != 0
+  static int thermal_runaway_bed_state_machine;
+  static unsigned long thermal_runaway_bed_timer;
+#endif
 #endif
 
 FORCE_INLINE void autotempShutdown(){
- #ifdef AUTOTEMP
- if(autotemp_enabled)
- {
-  autotemp_enabled=false;
-  if(degTargetHotend(active_extruder)>autotemp_min)
-    setTargetHotend(0,active_extruder);
- }
- #endif
+#ifdef AUTOTEMP
+  if(autotemp_enabled)
+  {
+    autotemp_enabled=false;
+    if(degTargetHotend(active_extruder)>autotemp_min)
+      setTargetHotend(0,active_extruder);
+  }
+#endif
 }
 
 void PID_autotune(float temp, int extruder, int ncycles);
 void checkExtruderAutoFans();
 
 #endif
-

Marlin/thermistortables.h

 
 #define OVERSAMPLENR 16
 
-#if (THERMISTORHEATER_0 == 1) || (THERMISTORHEATER_1 == 1)  || (THERMISTORHEATER_2 == 1) || (THERMISTORBED == 1) //100k bed thermistor
+#if (THERMISTORHEATER_0 == 1) || (THERMISTORHEATER_1 == 1)  || (THERMISTORHEATER_2 == 1) || (THERMISTORHEATER_3 == 1) || (THERMISTORBED == 1) //100k bed thermistor
 
 const short temptable_1[][2] PROGMEM = {
 {       23*OVERSAMPLENR ,       300     },
 {       1008*OVERSAMPLENR       ,       0       } //safety
 };
 #endif
-#if (THERMISTORHEATER_0 == 2) || (THERMISTORHEATER_1 == 2) || (THERMISTORHEATER_2 == 2) || (THERMISTORBED == 2) //200k bed thermistor
+#if (THERMISTORHEATER_0 == 2) || (THERMISTORHEATER_1 == 2) || (THERMISTORHEATER_2 == 2) || (THERMISTORHEATER_3 == 2) || (THERMISTORBED == 2) //200k bed thermistor
 const short temptable_2[][2] PROGMEM = {
 //200k ATC Semitec 204GT-2
 //Verified by linagee. Source: http://shop.arcol.hu/static/datasheets/thermistors.pdf
 };
 
 #endif
-#if (THERMISTORHEATER_0 == 3) || (THERMISTORHEATER_1 == 3) || (THERMISTORHEATER_2 == 3) || (THERMISTORBED == 3) //mendel-parts
+#if (THERMISTORHEATER_0 == 3) || (THERMISTORHEATER_1 == 3) || (THERMISTORHEATER_2 == 3) || (THERMISTORHEATER_3 == 3) || (THERMISTORBED == 3) //mendel-parts
 const short temptable_3[][2] PROGMEM = {
                 {1*OVERSAMPLENR,864},
                 {21*OVERSAMPLENR,300},
         };
 
 #endif
-#if (THERMISTORHEATER_0 == 4) || (THERMISTORHEATER_1 == 4) || (THERMISTORHEATER_2 == 4) || (THERMISTORBED == 4) //10k thermistor
+#if (THERMISTORHEATER_0 == 4) || (THERMISTORHEATER_1 == 4) || (THERMISTORHEATER_2 == 4) || (THERMISTORHEATER_3 == 4) || (THERMISTORBED == 4) //10k thermistor
 const short temptable_4[][2] PROGMEM = {
    {1*OVERSAMPLENR, 430},
    {54*OVERSAMPLENR, 137},
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 5) || (THERMISTORHEATER_1 == 5) || (THERMISTORHEATER_2 == 5) || (THERMISTORBED == 5) //100k ParCan thermistor (104GT-2)
+#if (THERMISTORHEATER_0 == 5) || (THERMISTORHEATER_1 == 5) || (THERMISTORHEATER_2 == 5) || (THERMISTORHEATER_3 == 5) || (THERMISTORBED == 5) //100k ParCan thermistor (104GT-2)
 const short temptable_5[][2] PROGMEM = {
 // ATC Semitec 104GT-2 (Used in ParCan)
 // Verified by linagee. Source: http://shop.arcol.hu/static/datasheets/thermistors.pdf
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 6) || (THERMISTORHEATER_1 == 6) || (THERMISTORHEATER_2 == 6) || (THERMISTORBED == 6) // 100k Epcos thermistor
+#if (THERMISTORHEATER_0 == 6) || (THERMISTORHEATER_1 == 6) || (THERMISTORHEATER_2 == 6) || (THERMISTORHEATER_3 == 6) || (THERMISTORBED == 6) // 100k Epcos thermistor
 const short temptable_6[][2] PROGMEM = {
    {1*OVERSAMPLENR, 350},
    {28*OVERSAMPLENR, 250}, //top rating 250C
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 7) || (THERMISTORHEATER_1 == 7) || (THERMISTORHEATER_2 == 7) || (THERMISTORBED == 7) // 100k Honeywell 135-104LAG-J01
+#if (THERMISTORHEATER_0 == 7) || (THERMISTORHEATER_1 == 7) || (THERMISTORHEATER_2 == 7) || (THERMISTORHEATER_3 == 7) || (THERMISTORBED == 7) // 100k Honeywell 135-104LAG-J01
 const short temptable_7[][2] PROGMEM = {
    {1*OVERSAMPLENR, 941},
    {19*OVERSAMPLENR, 362},
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 71) || (THERMISTORHEATER_1 == 71) || (THERMISTORHEATER_2 == 71) || (THERMISTORBED == 71) // 100k Honeywell 135-104LAF-J01
+#if (THERMISTORHEATER_0 == 71) || (THERMISTORHEATER_1 == 71) || (THERMISTORHEATER_2 == 71) || (THERMISTORHEATER_3 == 71) || (THERMISTORBED == 71) // 100k Honeywell 135-104LAF-J01
 // R0 = 100000 Ohm
 // T0 = 25 °C
 // Beta = 3974
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 8) || (THERMISTORHEATER_1 == 8) || (THERMISTORHEATER_2 == 8) || (THERMISTORBED == 8)
+#if (THERMISTORHEATER_0 == 8) || (THERMISTORHEATER_1 == 8) || (THERMISTORHEATER_2 == 8) || (THERMISTORHEATER_3 == 8) || (THERMISTORBED == 8)
 // 100k 0603 SMD Vishay NTCS0603E3104FXT (4.7k pullup)
 const short temptable_8[][2] PROGMEM = {
    {1*OVERSAMPLENR, 704},
    {1008*OVERSAMPLENR, 0}
 };
 #endif
-#if (THERMISTORHEATER_0 == 9) || (THERMISTORHEATER_1 == 9) || (THERMISTORHEATER_2 == 9) || (THERMISTORBED == 9)
+#if (THERMISTORHEATER_0 == 9) || (THERMISTORHEATER_1 == 9) || (THERMISTORHEATER_2 == 9) || (THERMISTORHEATER_3 == 9) || (THERMISTORBED == 9)
 // 100k GE Sensing AL03006-58.2K-97-G1 (4.7k pullup)
 const short temptable_9[][2] PROGMEM = {
 	{1*OVERSAMPLENR, 936},
 	{1016*OVERSAMPLENR, 0}
 };
 #endif
-#if (THERMISTORHEATER_0 == 10) || (THERMISTORHEATER_1 == 10) || (THERMISTORHEATER_2 == 10) || (THERMISTORBED == 10)
+#if (THERMISTORHEATER_0 == 10) || (THERMISTORHEATER_1 == 10) || (THERMISTORHEATER_2 == 10) || (THERMISTORHEATER_3 == 10) || (THERMISTORBED == 10)
 // 100k RS thermistor 198-961 (4.7k pullup)
 const short temptable_10[][2] PROGMEM = {
    {1*OVERSAMPLENR, 929},
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 11) || (THERMISTORHEATER_1 == 11) || (THERMISTORHEATER_2 == 11) || (THERMISTORBED == 11) 
+#if (THERMISTORHEATER_0 == 11) || (THERMISTORHEATER_1 == 11) || (THERMISTORHEATER_2 == 11) || (THERMISTORHEATER_3 == 11) || (THERMISTORBED == 11) 
 // QU-BD silicone bed QWG-104F-3950 thermistor
 
 const short temptable_11[][2] PROGMEM = {
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 13) || (THERMISTORHEATER_1 == 13) || (THERMISTORHEATER_2 == 13) || (THERMISTORBED == 13)
+#if (THERMISTORHEATER_0 == 13) || (THERMISTORHEATER_1 == 13) || (THERMISTORHEATER_2 == 13) || (THERMISTORHEATER_3 == 13) || (THERMISTORBED == 13)
 // Hisens thermistor B25/50 =3950 +/-1%
 
 const short temptable_13[][2] PROGMEM = {
 # define HEATER_2_RAW_HI_TEMP 16383
 # define HEATER_2_RAW_LO_TEMP 0
 #endif
+#if (THERMISTORHEATER_3 == 20)
+# define HEATER_3_RAW_HI_TEMP 16383
+# define HEATER_3_RAW_LO_TEMP 0
+#endif
 #if (THERMISTORBED == 20)
 # define HEATER_BED_RAW_HI_TEMP 16383
 # define HEATER_BED_RAW_LO_TEMP 0
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 51) || (THERMISTORHEATER_1 == 51) || (THERMISTORHEATER_2 == 51) || (THERMISTORBED == 51)
+#if (THERMISTORHEATER_0 == 51) || (THERMISTORHEATER_1 == 51) || (THERMISTORHEATER_2 == 51) || (THERMISTORHEATER_3 == 51) || (THERMISTORBED == 51)
 // 100k EPCOS (WITH 1kohm RESISTOR FOR PULLUP, R9 ON SANGUINOLOLU! NOT FOR 4.7kohm PULLUP! THIS IS NOT NORMAL!)
 // Verified by linagee.
 // Calculated using 1kohm pullup, voltage divider math, and manufacturer provided temp/resistance
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 52) || (THERMISTORHEATER_1 == 52) || (THERMISTORHEATER_2 == 52) || (THERMISTORBED == 52) 
+#if (THERMISTORHEATER_0 == 52) || (THERMISTORHEATER_1 == 52) || (THERMISTORHEATER_2 == 52) || (THERMISTORHEATER_3 == 52) || (THERMISTORBED == 52) 
 // 200k ATC Semitec 204GT-2 (WITH 1kohm RESISTOR FOR PULLUP, R9 ON SANGUINOLOLU! NOT FOR 4.7kohm PULLUP! THIS IS NOT NORMAL!)
 // Verified by linagee. Source: http://shop.arcol.hu/static/datasheets/thermistors.pdf
 // Calculated using 1kohm pullup, voltage divider math, and manufacturer provided temp/resistance
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 55) || (THERMISTORHEATER_1 == 55) || (THERMISTORHEATER_2 == 55) || (THERMISTORBED == 55) 
+#if (THERMISTORHEATER_0 == 55) || (THERMISTORHEATER_1 == 55) || (THERMISTORHEATER_2 == 55) || (THERMISTORHEATER_3 == 55) || (THERMISTORBED == 55) 
 // 100k ATC Semitec 104GT-2 (Used on ParCan) (WITH 1kohm RESISTOR FOR PULLUP, R9 ON SANGUINOLOLU! NOT FOR 4.7kohm PULLUP! THIS IS NOT NORMAL!)
 // Verified by linagee. Source: http://shop.arcol.hu/static/datasheets/thermistors.pdf
 // Calculated using 1kohm pullup, voltage divider math, and manufacturer provided temp/resistance
 };
 #endif
 
-#if (THERMISTORHEATER_0 == 60) || (THERMISTORHEATER_1 == 60) || (THERMISTORHEATER_2 == 60) || (THERMISTORBED == 60) // Maker's Tool Works Kapton Bed Thermister
+#if (THERMISTORHEATER_0 == 60) || (THERMISTORHEATER_1 == 60) || (THERMISTORHEATER_2 == 60) || (THERMISTORHEATER_3 == 60) || (THERMISTORBED == 60) // Maker's Tool Works Kapton Bed Thermister
 // ./createTemperatureLookup.py --r0=100000 --t0=25 --r1=0 --r2=4700 --beta=3950 
 // r0: 100000
 // t0: 25
 #define PtAdVal(T,R0,Rup) (short)(1024/(Rup/PtRt(T,R0)+1))
 #define PtLine(T,R0,Rup) { PtAdVal(T,R0,Rup)*OVERSAMPLENR, T },
 
-#if (THERMISTORHEATER_0 == 110) || (THERMISTORHEATER_1 == 110) || (THERMISTORHEATER_2 == 110) || (THERMISTORBED == 110) // Pt100 with 1k0 pullup
+#if (THERMISTORHEATER_0 == 110) || (THERMISTORHEATER_1 == 110) || (THERMISTORHEATER_2 == 110) || (THERMISTORHEATER_3 == 110) || (THERMISTORBED == 110) // Pt100 with 1k0 pullup
 const short temptable_110[][2] PROGMEM = {
 // only few values are needed as the curve is very flat  
   PtLine(0,100,1000)
   PtLine(300,100,1000)
 };
 #endif
-#if (THERMISTORHEATER_0 == 147) || (THERMISTORHEATER_1 == 147) || (THERMISTORHEATER_2 == 147) || (THERMISTORBED == 147) // Pt100 with 4k7 pullup
+#if (THERMISTORHEATER_0 == 147) || (THERMISTORHEATER_1 == 147) || (THERMISTORHEATER_2 == 147) || (THERMISTORHEATER_3 == 147) || (THERMISTORBED == 147) // Pt100 with 4k7 pullup
 const short temptable_147[][2] PROGMEM = {
 // only few values are needed as the curve is very flat  
   PtLine(0,100,4700)
   PtLine(300,100,4700)
 };
 #endif
-#if (THERMISTORHEATER_0 == 1010) || (THERMISTORHEATER_1 == 1010) || (THERMISTORHEATER_2 == 1010) || (THERMISTORBED == 1010) // Pt1000 with 1k0 pullup
+#if (THERMISTORHEATER_0 == 1010) || (THERMISTORHEATER_1 == 1010) || (THERMISTORHEATER_2 == 1010) || (THERMISTORHEATER_3 == 1010) || (THERMISTORBED == 1010) // Pt1000 with 1k0 pullup
 const short temptable_1010[][2] PROGMEM = {
   PtLine(0,1000,1000)
   PtLine(25,1000,1000)
   PtLine(300,1000,1000)
 };
 #endif
-#if (THERMISTORHEATER_0 == 1047) || (THERMISTORHEATER_1 == 1047) || (THERMISTORHEATER_2 == 1047) || (THERMISTORBED == 1047) // Pt1000 with 4k7 pullup
+#if (THERMISTORHEATER_0 == 1047) || (THERMISTORHEATER_1 == 1047) || (THERMISTORHEATER_2 == 1047) || (THERMISTORHEATER_3 == 1047) || (THERMISTORBED == 1047) // Pt1000 with 4k7 pullup
 const short temptable_1047[][2] PROGMEM = {
 // only few values are needed as the curve is very flat  
   PtLine(0,1000,4700)
 # endif
 #endif
 
+#ifdef THERMISTORHEATER_3
+# define HEATER_3_TEMPTABLE TT_NAME(THERMISTORHEATER_3)
+# define HEATER_3_TEMPTABLE_LEN (sizeof(HEATER_3_TEMPTABLE)/sizeof(*HEATER_3_TEMPTABLE))
+#else
+# ifdef HEATER_3_USES_THERMISTOR
+#  error No heater 3 thermistor table specified
+# else  // HEATER_3_USES_THERMISTOR
+#  define HEATER_3_TEMPTABLE NULL
+#  define HEATER_3_TEMPTABLE_LEN 0
+# endif // HEATER_3_USES_THERMISTOR
+#endif
+
+//Set the high and low raw values for the heater, this indicates which raw value is a high or low temperature
+#ifndef HEATER_3_RAW_HI_TEMP
+# ifdef HEATER_3_USES_THERMISTOR   //In case of a thermistor the highest temperature results in the lowest ADC value
+#  define HEATER_3_RAW_HI_TEMP 0
+#  define HEATER_3_RAW_LO_TEMP 16383
+# else                          //In case of an thermocouple the highest temperature results in the highest ADC value
+#  define HEATER_3_RAW_HI_TEMP 16383
+#  define HEATER_3_RAW_LO_TEMP 0
+# endif
+#endif
+
 #ifdef THERMISTORBED
 # define BEDTEMPTABLE TT_NAME(THERMISTORBED)
 # define BEDTEMPTABLE_LEN (sizeof(BEDTEMPTABLE)/sizeof(*BEDTEMPTABLE))

Marlin/ultralcd.cpp

 #if TEMP_SENSOR_2 != 0
     MENU_ITEM_EDIT(int3, MSG_NOZZLE2, &target_temperature[2], 0, HEATER_2_MAXTEMP - 15);
 #endif
+#if TEMP_SENSOR_3 != 0
+    MENU_ITEM_EDIT(int3, MSG_NOZZLE3, &target_temperature[3], 0, HEATER_3_MAXTEMP - 15);
+#endif
+
+
 #if TEMP_SENSOR_BED != 0
     MENU_ITEM_EDIT(int3, MSG_BED, &target_temperature_bed, 0, BED_MAXTEMP - 15);
 #endif
 #if TEMP_SENSOR_2 != 0
     MENU_ITEM_EDIT(int3, MSG_FLOW2, &extruder_multiply[2], 10, 999);
 #endif
+#if TEMP_SENSOR_3 != 0
+    MENU_ITEM_EDIT(int3, MSG_FLOW3, &extruder_multiply[3], 10, 999);
+#endif
+
 
 #ifdef BABYSTEPPING
     #ifdef BABYSTEP_XY
 }
 #endif //3 extruder preheat
 
-#if TEMP_SENSOR_1 != 0 || TEMP_SENSOR_2 != 0 //more than one extruder present
-void lcd_preheat_pla012()
+#if TEMP_SENSOR_3 != 0 //4 extruder preheat
+void lcd_preheat_pla3()
+{
+    setTargetHotend3(plaPreheatHotendTemp);
+    setTargetBed(plaPreheatHPBTemp);
+    fanSpeed = plaPreheatFanSpeed;
+    lcd_return_to_status();
+    setWatch(); // heater sanity check timer
+}
+
+void lcd_preheat_abs3()
+{
+    setTargetHotend3(absPreheatHotendTemp);
+    setTargetBed(absPreheatHPBTemp);
+    fanSpeed = absPreheatFanSpeed;
+    lcd_return_to_status();
+    setWatch(); // heater sanity check timer
+}
+
+#endif //4 extruder preheat
+
+#if TEMP_SENSOR_1 != 0 || TEMP_SENSOR_2 != 0 || TEMP_SENSOR_3 != 0 //more than one extruder present
+void lcd_preheat_pla0123()
 {
     setTargetHotend0(plaPreheatHotendTemp);
     setTargetHotend1(plaPreheatHotendTemp);
     setTargetHotend2(plaPreheatHotendTemp);
+    setTargetHotend3(plaPreheatHotendTemp);
     setTargetBed(plaPreheatHPBTemp);
     fanSpeed = plaPreheatFanSpeed;
     lcd_return_to_status();
     setWatch(); // heater sanity check timer
 }
 
-void lcd_preheat_abs012()
+void lcd_preheat_abs0123()
 {
     setTargetHotend0(absPreheatHotendTemp);
     setTargetHotend1(absPreheatHotendTemp);
     setTargetHotend2(absPreheatHotendTemp);
+    setTargetHotend3(absPreheatHotendTemp);
     setTargetBed(absPreheatHPBTemp);
     fanSpeed = absPreheatFanSpeed;
     lcd_return_to_status();
 
 static void lcd_preheat_pla_menu()
 {
-    START_MENU();
-    MENU_ITEM(back, MSG_PREPARE, lcd_prepare_menu);
-    MENU_ITEM(function, MSG_PREHEAT_PLA0, lcd_preheat_pla0);
+  START_MENU();
+  MENU_ITEM(back, MSG_PREPARE, lcd_prepare_menu);
+  MENU_ITEM(function, MSG_PREHEAT_PLA0, lcd_preheat_pla0);
 #if TEMP_SENSOR_1 != 0 //2 extruder preheat
-    MENU_ITEM(function, MSG_PREHEAT_PLA1, lcd_preheat_pla1);
+  MENU_ITEM(function, MSG_PREHEAT_PLA1, lcd_preheat_pla1);
 #endif //2 extruder preheat
 #if TEMP_SENSOR_2 != 0 //3 extruder preheat
-    MENU_ITEM(function, MSG_PREHEAT_PLA2, lcd_preheat_pla2);
+  MENU_ITEM(function, MSG_PREHEAT_PLA2, lcd_preheat_pla2);
 #endif //3 extruder preheat
-#if TEMP_SENSOR_1 != 0 || TEMP_SENSOR_2 != 0 //all extruder preheat
-    MENU_ITEM(function, MSG_PREHEAT_PLA012, lcd_preheat_pla012);
-#endif //2 extruder preheat
+#if TEMP_SENSOR_3 != 0 //4 extruder preheat
+  MENU_ITEM(function, MSG_PREHEAT_PLA3, lcd_preheat_pla3);
+#endif //4 extruder preheat
+#if TEMP_SENSOR_1 != 0 || TEMP_SENSOR_2 != 0 || TEMP_SENSOR_3 != 0 //all extruder preheat
+  MENU_ITEM(function, MSG_PREHEAT_PLA0123, lcd_preheat_pla0123);
+#endif //all extruder preheat
 #if TEMP_SENSOR_BED != 0
-    MENU_ITEM(function, MSG_PREHEAT_PLA_BEDONLY, lcd_preheat_pla_bedonly);
+  MENU_ITEM(function, MSG_PREHEAT_PLA_BEDONLY, lcd_preheat_pla_bedonly);
 #endif
-    END_MENU();
+  END_MENU();
 }
 
 static void lcd_preheat_abs_menu()
 {
-    START_MENU();
-    MENU_ITEM(back, MSG_PREPARE, lcd_prepare_menu);
-    MENU_ITEM(function, MSG_PREHEAT_ABS0, lcd_preheat_abs0);
+  START_MENU();
+  MENU_ITEM(back, MSG_PREPARE, lcd_prepare_menu);
+  MENU_ITEM(function, MSG_PREHEAT_ABS0, lcd_preheat_abs0);
 #if TEMP_SENSOR_1 != 0 //2 extruder preheat
-    MENU_ITEM(function, MSG_PREHEAT_ABS1, lcd_preheat_abs1);
+	MENU_ITEM(function, MSG_PREHEAT_ABS1, lcd_preheat_abs1);
 #endif //2 extruder preheat
 #if TEMP_SENSOR_2 != 0 //3 extruder preheat
-    MENU_ITEM(function, MSG_PREHEAT_ABS2, lcd_preheat_abs2);
+  MENU_ITEM(function, MSG_PREHEAT_ABS2, lcd_preheat_abs2);
 #endif //3 extruder preheat
-#if TEMP_SENSOR_1 != 0 || TEMP_SENSOR_2 != 0 //all extruder preheat
-    MENU_ITEM(function, MSG_PREHEAT_ABS012, lcd_preheat_abs012);
-#endif //2 extruder preheat
+#if TEMP_SENSOR_3 != 0 //4 extruder preheat
+  MENU_ITEM(function, MSG_PREHEAT_ABS3, lcd_preheat_abs3);
+#endif //4 extruder preheat
+#if TEMP_SENSOR_1 != 0 || TEMP_SENSOR_2 != 0 || TEMP_SENSOR_3 != 0 //all extruder preheat
+  MENU_ITEM(function, MSG_PREHEAT_ABS0123, lcd_preheat_abs0123);
+#endif //all extruder preheat
+
 #if TEMP_SENSOR_BED != 0
-    MENU_ITEM(function, MSG_PREHEAT_ABS_BEDONLY, lcd_preheat_abs_bedonly);
+ MENU_ITEM(function, MSG_PREHEAT_ABS_BEDONLY, lcd_preheat_abs_bedonly);
 #endif
-    END_MENU();
+  END_MENU();
 }
 
 void lcd_cooldown()
     setTargetHotend0(0);
     setTargetHotend1(0);
     setTargetHotend2(0);
+    setTargetHotend3(0);
     setTargetBed(0);
     fanSpeed = 0;
     lcd_return_to_status();
     MENU_ITEM(back, MSG_MAIN, lcd_main_menu);
     MENU_ITEM(submenu, MSG_TEMPERATURE, lcd_control_temperature_menu);
     MENU_ITEM(submenu, MSG_MOTION, lcd_control_motion_menu);
-	MENU_ITEM(submenu, MSG_VOLUMETRIC, lcd_control_volumetric_menu);
+    MENU_ITEM(submenu, MSG_VOLUMETRIC, lcd_control_volumetric_menu);
 
 #ifdef DOGLCD
 //    MENU_ITEM_EDIT(int3, MSG_CONTRAST, &lcd_contrast, 0, 63);
 
 static void lcd_control_temperature_menu()
 {
-    START_MENU();
-    MENU_ITEM(back, MSG_CONTROL, lcd_control_menu);
+  START_MENU();
+  MENU_ITEM(back, MSG_CONTROL, lcd_control_menu);
 #if TEMP_SENSOR_0 != 0
-    MENU_ITEM_EDIT(int3, MSG_NOZZLE, &target_temperature[0], 0, HEATER_0_MAXTEMP - 15);
+  MENU_ITEM_EDIT(int3, MSG_NOZZLE, &target_temperature[0], 0, HEATER_0_MAXTEMP - 15);
 #endif
 #if TEMP_SENSOR_1 != 0
-    MENU_ITEM_EDIT(int3, MSG_NOZZLE1, &target_temperature[1], 0, HEATER_1_MAXTEMP - 15);
+  MENU_ITEM_EDIT(int3, MSG_NOZZLE1, &target_temperature[1], 0, HEATER_1_MAXTEMP - 15);
 #endif
 #if TEMP_SENSOR_2 != 0
-    MENU_ITEM_EDIT(int3, MSG_NOZZLE2, &target_temperature[2], 0, HEATER_2_MAXTEMP - 15);
+  MENU_ITEM_EDIT(int3, MSG_NOZZLE2, &target_temperature[2], 0, HEATER_2_MAXTEMP - 15);
+#endif
+#if TEMP_SENSOR_3 != 0
+  MENU_ITEM_EDIT(int3, MSG_NOZZLE3, &target_temperature[3], 0, HEATER_3_MAXTEMP - 15);
 #endif
 #if TEMP_SENSOR_BED != 0
-    MENU_ITEM_EDIT(int3, MSG_BED, &target_temperature_bed, 0, BED_MAXTEMP - 15);
+  MENU_ITEM_EDIT(int3, MSG_BED, &target_temperature_bed, 0, BED_MAXTEMP - 15);
 #endif
-    MENU_ITEM_EDIT(int3, MSG_FAN_SPEED, &fanSpeed, 0, 255);
+  MENU_ITEM_EDIT(int3, MSG_FAN_SPEED, &fanSpeed, 0, 255);
 #if defined AUTOTEMP && (TEMP_SENSOR_0 != 0)
-    MENU_ITEM_EDIT(bool, MSG_AUTOTEMP, &autotemp_enabled);
-    MENU_ITEM_EDIT(float3, MSG_MIN, &autotemp_min, 0, HEATER_0_MAXTEMP - 15);
-    MENU_ITEM_EDIT(float3, MSG_MAX, &autotemp_max, 0, HEATER_0_MAXTEMP - 15);
-    MENU_ITEM_EDIT(float32, MSG_FACTOR, &autotemp_factor, 0.0, 1.0);
+  MENU_ITEM_EDIT(bool, MSG_AUTOTEMP, &autotemp_enabled);
+  MENU_ITEM_EDIT(float3, MSG_MIN, &autotemp_min, 0, HEATER_0_MAXTEMP - 15);
+  MENU_ITEM_EDIT(float3, MSG_MAX, &autotemp_max, 0, HEATER_0_MAXTEMP - 15);
+  MENU_ITEM_EDIT(float32, MSG_FACTOR, &autotemp_factor, 0.0, 1.0);
 #endif
 #ifdef PIDTEMP
 	// set up temp variables - undo the default scaling
 		MENU_ITEM_EDIT_CALLBACK(float43, MSG_FILAMENT_SIZE_EXTRUDER_1, &filament_size[1], DEFAULT_NOMINAL_FILAMENT_DIA - .5, DEFAULT_NOMINAL_FILAMENT_DIA + .5, calculate_volumetric_multipliers);
 #if EXTRUDERS > 2
 		MENU_ITEM_EDIT_CALLBACK(float43, MSG_FILAMENT_SIZE_EXTRUDER_2, &filament_size[2], DEFAULT_NOMINAL_FILAMENT_DIA - .5, DEFAULT_NOMINAL_FILAMENT_DIA + .5, calculate_volumetric_multipliers);
-#endif
-#endif
+#if EXTRUDERS > 3
+		MENU_ITEM_EDIT_CALLBACK(float43, MSG_FILAMENT_SIZE_EXTRUDER_3, &filament_size[3], DEFAULT_NOMINAL_FILAMENT_DIA - .5, DEFAULT_NOMINAL_FILAMENT_DIA + .5, calculate_volumetric_multipliers);
+#endif //EXTRUDERS > 3
+#endif //EXTRUDERS > 2
+#endif //EXTRUDERS > 1
 	}
 
 	END_MENU();
 }
-
 #ifdef DOGLCD
 static void lcd_set_contrast()
 {
     MENU_ITEM(back, MSG_CONTROL, lcd_control_menu);
     MENU_ITEM_EDIT(bool, MSG_AUTORETRACT, &autoretract_enabled);
     MENU_ITEM_EDIT(float52, MSG_CONTROL_RETRACT, &retract_length, 0, 100);
-	#if EXTRUDERS > 1
+    #if EXTRUDERS > 1
       MENU_ITEM_EDIT(float52, MSG_CONTROL_RETRACT_SWAP, &retract_length_swap, 0, 100);
     #endif
     MENU_ITEM_EDIT(float3, MSG_CONTROL_RETRACTF, &retract_feedrate, 1, 999);
     MENU_ITEM_EDIT(float52, MSG_CONTROL_RETRACT_ZLIFT, &retract_zlift, 0, 999);
     MENU_ITEM_EDIT(float52, MSG_CONTROL_RETRACT_RECOVER, &retract_recover_length, 0, 100);
-	#if EXTRUDERS > 1
+    #if EXTRUDERS > 1
       MENU_ITEM_EDIT(float52, MSG_CONTROL_RETRACT_RECOVER_SWAP, &retract_recover_length_swap, 0, 100);
     #endif
     MENU_ITEM_EDIT(float3, MSG_CONTROL_RETRACT_RECOVERF, &retract_recover_feedrate, 1, 999);
     END_MENU();
 }
-
 #endif //FWRETRACT
 
 #if SDCARDDETECT == -1

Marlin/ultralcd.h

   
   extern bool cancel_heatup;
   
-  #ifdef FILAMENT_LCD_DISPLAY
-        extern unsigned long message_millis;
-  #endif
+#ifdef FILAMENT_LCD_DISPLAY
+  extern unsigned long message_millis;
+#endif
 
   void lcd_buzz(long duration,uint16_t freq);
   bool lcd_clicked();