✨ Redundant Part Cooling Fan (#21888)

Co-authored-by: Scott Lahteine <github@thinkyhead.com>

Marlin/Configuration_adv.h

@@ -532,6 +532,11 @@
   //#define USE_OCR2A_AS_TOP
 #endif
 
+/**
+ * Use one of the PWM fans as a redundant part-cooling fan
+ */
+//#define REDUNDANT_PART_COOLING_FAN 2  // Index of the fan to sync with FAN 0.
+
 // @section extruder
 
 /**

Marlin/src/gcode/temp/M106_M107.cpp

@@ -60,8 +60,10 @@
  */
 void GcodeSuite::M106() {
   const uint8_t pfan = parser.byteval('P', _ALT_P);
-
-  if (pfan < _CNT_P) {
+  if (pfan >= _CNT_P) return;
+  #if REDUNDANT_PART_COOLING_FAN
+    if (pfan == REDUNDANT_PART_COOLING_FAN) return;
+  #endif
 
   #if ENABLED(EXTRA_FAN_SPEED)
     const uint16_t t = parser.intval('T');
@@ -93,7 +95,6 @@ void GcodeSuite::M106() {
   if (TERN0(DUAL_X_CARRIAGE, idex_is_duplicating()))  // pfan == 0 when duplicating
     thermalManager.set_fan_speed(1 - pfan, speed);
 }
-}
 
 /**
  * M107: Fan Off
@@ -101,6 +102,9 @@ void GcodeSuite::M106() {
 void GcodeSuite::M107() {
   const uint8_t pfan = parser.byteval('P', _ALT_P);
   if (pfan >= _CNT_P) return;
+  #if REDUNDANT_PART_COOLING_FAN
+    if (pfan == REDUNDANT_PART_COOLING_FAN) return;
+  #endif
 
   thermalManager.set_fan_speed(pfan, 0);
 

Marlin/src/inc/SanityCheck.h

@@ -1890,6 +1890,14 @@ static_assert(Y_MAX_LENGTH >= Y_BED_SIZE, "Movement bounds (Y_MIN_POS, Y_MAX_POS
   #endif
 #endif
 
+#ifdef REDUNDANT_PART_COOLING_FAN
+  #if FAN_COUNT < 2
+    #error "REDUNDANT_PART_COOLING_FAN requires a board with at least two PWM fans."
+  #else
+    static_assert(WITHIN(REDUNDANT_PART_COOLING_FAN, 1, FAN_COUNT - 1), "REDUNDANT_PART_COOLING_FAN must be between 1 and " STRINGIFY(DECREMENT(FAN_COUNT)) ".");
+  #endif
+#endif
+
 /**
  * Case Light requirements
  */

Marlin/src/lcd/menu/menu_temperature.cpp

@@ -57,8 +57,14 @@ void Temperature::lcd_preheat(const uint8_t e, const int8_t indh, const int8_t i
     if (indb >= 0 && ui.material_preset[indb].bed_temp > 0) setTargetBed(ui.material_preset[indb].bed_temp);
   #endif
   #if HAS_FAN
-    if (indh >= 0)
-      set_fan_speed(active_extruder < (FAN_COUNT) ? active_extruder : 0, ui.material_preset[indh].fan_speed);
+    if (indh >= 0) {
+      const uint8_t fan_index = active_extruder < (FAN_COUNT) ? active_extruder : 0;
+      if (true
+        #if REDUNDANT_PART_COOLING_FAN
+          && fan_index != REDUNDANT_PART_COOLING_FAN
+        #endif
+      ) set_fan_speed(fan_index, ui.material_preset[indh].fan_speed);
+    }
   #endif
   ui.return_to_status();
 }
@@ -215,37 +221,37 @@ void menu_temperature() {
     #if HAS_FAN0
       _FAN_EDIT_ITEMS(0,FIRST_FAN_SPEED);
     #endif
-    #if HAS_FAN1
+    #if HAS_FAN1 && REDUNDANT_PART_COOLING_FAN != 1
       FAN_EDIT_ITEMS(1);
     #elif SNFAN(1)
       singlenozzle_item(1);
     #endif
-    #if HAS_FAN2
+    #if HAS_FAN2 && REDUNDANT_PART_COOLING_FAN != 2
       FAN_EDIT_ITEMS(2);
     #elif SNFAN(2)
       singlenozzle_item(2);
     #endif
-    #if HAS_FAN3
+    #if HAS_FAN3 && REDUNDANT_PART_COOLING_FAN != 3
       FAN_EDIT_ITEMS(3);
     #elif SNFAN(3)
       singlenozzle_item(3);
     #endif
-    #if HAS_FAN4
+    #if HAS_FAN4 && REDUNDANT_PART_COOLING_FAN != 4
       FAN_EDIT_ITEMS(4);
     #elif SNFAN(4)
       singlenozzle_item(4);
     #endif
-    #if HAS_FAN5
+    #if HAS_FAN5 && REDUNDANT_PART_COOLING_FAN != 5
       FAN_EDIT_ITEMS(5);
     #elif SNFAN(5)
       singlenozzle_item(5);
     #endif
-    #if HAS_FAN6
+    #if HAS_FAN6 && REDUNDANT_PART_COOLING_FAN != 6
       FAN_EDIT_ITEMS(6);
     #elif SNFAN(6)
       singlenozzle_item(6);
     #endif
-    #if HAS_FAN7
+    #if HAS_FAN7 && REDUNDANT_PART_COOLING_FAN != 7
       FAN_EDIT_ITEMS(7);
     #elif SNFAN(7)
       singlenozzle_item(7);

Marlin/src/module/temperature.cpp

@@ -333,6 +333,9 @@ const char str_t_thermal_runaway[] PROGMEM = STR_T_THERMAL_RUNAWAY,
     if (fan >= FAN_COUNT) return;
 
     fan_speed[fan] = speed;
+    #if REDUNDANT_PART_COOLING_FAN
+      if (fan == 0) fan_speed[REDUNDANT_PART_COOLING_FAN] = speed;
+    #endif
 
     TERN_(REPORT_FAN_CHANGE, report_fan_speed(fan));
   }

buildroot/tests/mega2560

@@ -68,7 +68,8 @@ exec_test $1 $2 "Multiple runout sensors (x5) | Distinct runout states" "$3"
 #
 restore_configs
 opt_set MOTHERBOARD BOARD_AZTEEG_X3_PRO MIXING_STEPPERS 5 LCD_LANGUAGE ru \
-        NUM_RUNOUT_SENSORS E_STEPPERS FIL_RUNOUT2_PIN 16 FIL_RUNOUT3_PIN 17 FIL_RUNOUT4_PIN 4 FIL_RUNOUT5_PIN 5
+        NUM_RUNOUT_SENSORS E_STEPPERS REDUNDANT_PART_COOLING_FAN 1 \
+        FIL_RUNOUT2_PIN 16 FIL_RUNOUT3_PIN 17 FIL_RUNOUT4_PIN 4 FIL_RUNOUT5_PIN 5
 opt_enable MIXING_EXTRUDER GRADIENT_MIX GRADIENT_VTOOL CR10_STOCKDISPLAY \
            USE_CONTROLLER_FAN CONTROLLER_FAN_EDITABLE CONTROLLER_FAN_IGNORE_Z \
            FILAMENT_RUNOUT_SENSOR ADVANCED_PAUSE_FEATURE NOZZLE_PARK_FEATURE