Hotend Protection - Prevent deep-fried filament clogs

Marlin/Configuration_adv.h

@@ -330,6 +330,18 @@
   #define EXTRUDER_RUNOUT_EXTRUDE 5   // (mm)
 #endif
 
+/**
+ * Hotend Idle Timeout
+ * Prevent filament in the nozzle from charring and causing a critical jam.
+ */
+//#define HOTEND_IDLE_TIMEOUT
+#if ENABLED(HOTEND_IDLE_TIMEOUT)
+  #define HOTEND_IDLE_DURATION_SEC    5     // (minutes) Time without extruder movement to trigger protection
+  #define HOTEND_IDLE_MIN_TRIGGER   180     // (°C) Minimum temperature to enable hotend protection
+  #define HOTEND_IDLE_NOZZLE_TARGET   0     // (°C) Safe temperature for the nozzle after timeout
+  #define HOTEND_IDLE_BED_TARGET      0     // (°C) Safe temperature for the bed after timeout
+#endif
+
 // @section temperature
 
 // Calibration for AD595 / AD8495 sensor to adjust temperature measurements.
@@ -3308,7 +3320,7 @@
    */
 
   //#define MMU_EXTRUDER_SENSOR
-  #if ENABLED(MMU_EXTRUDER_SENSOR) 
+  #if ENABLED(MMU_EXTRUDER_SENSOR)
     #define MMU_LOADING_ATTEMPTS_NR 5 //max. number of attempts to load filament if first load fail
   #endif
 

Marlin/src/MarlinCore.cpp

@@ -159,6 +159,10 @@
   #include "feature/runout.h"
 #endif
 
+#if ENABLED(HOTEND_IDLE_TIMEOUT)
+  #include "feature/hotend_idle.h"
+#endif
+
 #if ENABLED(TEMP_STAT_LEDS)
   #include "feature/leds/tempstat.h"
 #endif
@@ -527,6 +531,8 @@ inline void manage_inactivity(const bool ignore_stepper_queue=false) {
 
   TERN_(AUTO_POWER_CONTROL, powerManager.check());
 
+  TERN_(HOTEND_IDLE_TIMEOUT, hotend_idle.check());
+
   #if ENABLED(EXTRUDER_RUNOUT_PREVENT)
     if (thermalManager.degHotend(active_extruder) > EXTRUDER_RUNOUT_MINTEMP
       && ELAPSED(ms, gcode.previous_move_ms + SEC_TO_MS(EXTRUDER_RUNOUT_SECONDS))

Marlin/src/feature/hotend_idle.cpp

@@ -0,0 +1,89 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+/**
+ * Hotend Idle Timeout
+ * Prevent filament in the nozzle from charring and causing a critical jam.
+ */
+
+#include "../inc/MarlinConfig.h"
+
+#if ENABLED(HOTEND_IDLE_TIMEOUT)
+
+#include "hotend_idle.h"
+#include "../gcode/gcode.h"
+
+#include "../module/temperature.h"
+#include "../module/motion.h"
+#include "../lcd/ultralcd.h"
+
+extern HotendIdleProtection hotend_idle;
+
+millis_t HotendIdleProtection::next_protect_ms = 0;
+
+void HotendIdleProtection::check_hotends(const millis_t &ms) {
+  bool do_prot = false;
+  HOTEND_LOOP() {
+    if (thermalManager.degHotendNear(e, HOTEND_IDLE_MIN_TRIGGER)) {
+      do_prot = true; break;
+    }
+  }
+  if (bool(next_protect_ms) != do_prot)
+    next_protect_ms = do_prot ? ms + hp_interval : 0;
+}
+
+void HotendIdleProtection::check_e_motion(const millis_t &ms) {
+  static float old_e_position = 0;
+  if (old_e_position != current_position.e) {
+    old_e_position = current_position.e;          // Track filament motion
+    if (next_protect_ms)                          // If some heater is on then...
+      next_protect_ms = ms + hp_interval;         // ...delay the timeout till later
+  }
+}
+
+void HotendIdleProtection::check() {
+  const millis_t ms = millis();                   // Shared millis
+
+  check_hotends(ms);                              // Any hotends need protection?
+  check_e_motion(ms);                             // Motion will protect them
+
+  // Hot and not moving for too long...
+  if (next_protect_ms && ELAPSED(ms, next_protect_ms))
+    timed_out();
+}
+
+// Lower (but don't raise) hotend / bed temperatures
+void HotendIdleProtection::timed_out() {
+  next_protect_ms = 0;
+  SERIAL_ECHOLNPGM("Hotend Idle Timeout");
+  LCD_MESSAGEPGM(MSG_HOTEND_IDLE_TIMEOUT);
+  HOTEND_LOOP() {
+    if ((HOTEND_IDLE_NOZZLE_TARGET) < thermalManager.degTargetHotend(e))
+      thermalManager.setTargetHotend(HOTEND_IDLE_NOZZLE_TARGET, e);
+  }
+  #if HAS_HEATED_BED
+    if ((HOTEND_IDLE_BED_TARGET) < thermalManager.degTargetBed())
+      thermalManager.setTargetBed(HOTEND_IDLE_BED_TARGET);
+  #endif
+}
+
+#endif // HOTEND_IDLE_TIMEOUT

Marlin/src/feature/hotend_idle.h

@@ -0,0 +1,37 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#pragma once
+
+#include "../core/millis_t.h"
+
+class HotendIdleProtection {
+public:
+  static void check();
+private:
+  static constexpr millis_t hp_interval = SEC_TO_MS(HOTEND_IDLE_DURATION_SEC);
+  static millis_t next_protect_ms;
+  static void check_hotends(const millis_t &ms);
+  static void check_e_motion(const millis_t &ms);
+  static void timed_out();
+};
+
+extern HotendIdleProtection hotend_idle;

Marlin/src/inc/Conditionals_LCD.h

@@ -414,6 +414,7 @@
   #undef MIXING_EXTRUDER
   #undef MK2_MULTIPLEXER
   #undef PRUSA_MMU2
+  #undef HOTEND_IDLE_TIMEOUT
 #endif
 
 #if ENABLED(SWITCHING_EXTRUDER)   // One stepper for every two EXTRUDERS

Marlin/src/lcd/language/language_en.h

@@ -488,6 +488,7 @@ namespace Language_en {
   PROGMEM Language_Str MSG_INFO_PROTOCOL                   = _UxGT("Protocol");
   PROGMEM Language_Str MSG_INFO_RUNAWAY_OFF                = _UxGT("Runaway Watch: OFF");
   PROGMEM Language_Str MSG_INFO_RUNAWAY_ON                 = _UxGT("Runaway Watch: ON");
+  PROGMEM Language_Str MSG_HOTEND_IDLE_TIMEOUT             = _UxGT("Hotend Idle Timeout");
 
   PROGMEM Language_Str MSG_CASE_LIGHT                      = _UxGT("Case Light");
   PROGMEM Language_Str MSG_CASE_LIGHT_BRIGHTNESS           = _UxGT("Light Brightness");

Marlin/src/module/temperature.h

@@ -612,6 +612,10 @@ class Temperature {
         return degTargetHotend(e) > TEMP_HYSTERESIS && ABS(degHotend(e) - degTargetHotend(e)) > TEMP_HYSTERESIS;
       }
 
+      FORCE_INLINE static bool degHotendNear(const uint8_t e, const float &temp) {
+        return ABS(degHotend(e) - temp) < (TEMP_HYSTERESIS);
+      }
+
     #endif // HOTENDS
 
     #if HAS_HEATED_BED
@@ -650,6 +654,10 @@ class Temperature {
 
       static void wait_for_bed_heating();
 
+      FORCE_INLINE static bool degBedNear(const float &temp) {
+        return ABS(degBed() - temp) < (TEMP_BED_HYSTERESIS);
+      }
+
     #endif // HAS_HEATED_BED
 
     #if HAS_TEMP_PROBE

buildroot/share/tests/esp32-tests

@@ -31,7 +31,8 @@ opt_set X_HARDWARE_SERIAL Serial1
 opt_set Y_HARDWARE_SERIAL Serial1
 opt_set Z_HARDWARE_SERIAL Serial1
 opt_set E0_HARDWARE_SERIAL Serial1
-exec_test $1 $2 "ESP32 with TMC Hardware Serial"
+opt_enable HOTEND_IDLE_TIMEOUT
+exec_test $1 $2 "ESP32, TMC HW Serial, Hotend Idle"
 
 # cleanup
 restore_configs