From 29ad078fda7042a54710c7523a8255df49f291be Mon Sep 17 00:00:00 2001
From: Scott Lahteine <thinkyhead@users.noreply.github.com>
Date: Sun, 2 Nov 2025 21:48:24 -0600
Subject: [PATCH] =?UTF-8?q?=F0=9F=9A=B8=F0=9F=8C=A1=EF=B8=8F=20Refactor=20?=
 =?UTF-8?q?AUTOTEMP,=20apply=20to=20LCD=20temp=20change=20(#28155)?=
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Fixes #28154
---
 Marlin/src/core/language.h               |  1 +
 Marlin/src/gcode/gcode.h                 |  3 ++
 Marlin/src/gcode/temp/M104_M109.cpp      | 20 +++++++-
 Marlin/src/lcd/menu/menu_advanced.cpp    |  6 +--
 Marlin/src/lcd/menu/menu_temperature.cpp |  2 +-
 Marlin/src/lcd/menu/menu_tune.cpp        |  9 ++--
 Marlin/src/lcd/tft/touch.cpp             |  5 +-
 Marlin/src/module/planner.cpp            | 60 ++---------------------
 Marlin/src/module/planner.h              | 29 +++--------
 Marlin/src/module/settings.cpp           | 25 +++++-----
 Marlin/src/module/temperature.cpp        | 62 ++++++++++++++++++++++--
 Marlin/src/module/temperature.h          | 53 +++++++++++++++++++-
 Marlin/src/module/tool_change.cpp        |  2 +-
 buildroot/tests/mega2560                 |  2 +-
 14 files changed, 170 insertions(+), 109 deletions(-)

diff --git a/Marlin/src/core/language.h b/Marlin/src/core/language.h
index f2860ae7d4..e0a31db9ab 100644
--- a/Marlin/src/core/language.h
+++ b/Marlin/src/core/language.h
@@ -296,6 +296,7 @@
 #define STR_TOOL_CHANGING                   "Tool-changing"
 #define STR_HOTEND_OFFSETS                  "Hotend offsets"
 #define STR_SERVO_ANGLES                    "Servo Angles"
+#define STR_AUTOTEMP                        "Auto Temp Control"
 #define STR_HOTEND_PID                      "Hotend PID"
 #define STR_BED_PID                         "Bed PID"
 #define STR_CHAMBER_PID                     "Chamber PID"
diff --git a/Marlin/src/gcode/gcode.h b/Marlin/src/gcode/gcode.h
index effbd85449..a08ae769fe 100644
--- a/Marlin/src/gcode/gcode.h
+++ b/Marlin/src/gcode/gcode.h
@@ -766,6 +766,9 @@ private:
     static void M104_M109(const bool isM109);
     FORCE_INLINE static void M104() { M104_M109(false); }
     FORCE_INLINE static void M109() { M104_M109(true); }
+    #if ENABLED(AUTOTEMP)
+      static void M104_report(const bool forReplay=true);
+    #endif
   #endif
 
   static void M105();
diff --git a/Marlin/src/gcode/temp/M104_M109.cpp b/Marlin/src/gcode/temp/M104_M109.cpp
index 4df86edc55..fa6cc948c0 100644
--- a/Marlin/src/gcode/temp/M104_M109.cpp
+++ b/Marlin/src/gcode/temp/M104_M109.cpp
@@ -70,6 +70,9 @@
  *  (used by printingIsActive, etc.) and turning off heaters will stop the timer.
  */
 void GcodeSuite::M104_M109(const bool isM109) {
+  #if ENABLED(AUTOTEMP)
+    if (!isM109 && !parser.seen_any()) return M104_report();
+  #endif
 
   if (DEBUGGING(DRYRUN)) return;
 
@@ -125,10 +128,25 @@ void GcodeSuite::M104_M109(const bool isM109) {
       thermalManager.set_heating_message(target_extruder, !isM109 && got_temp);
   }
 
-  TERN_(AUTOTEMP, planner.autotemp_M104_M109());
+  TERN_(AUTOTEMP, thermalManager.autotemp_M104_M109());
 
   if (isM109 && got_temp)
     (void)thermalManager.wait_for_hotend(target_extruder, no_wait_for_cooling);
 }
 
+#if ENABLED(AUTOTEMP)
+  //
+  // Report AUTOTEMP settings saved to EEPROM
+  //
+  void GcodeSuite::M104_report(const bool forReplay/*=true*/) {
+    TERN_(MARLIN_SMALL_BUILD, return);
+      report_heading_etc(forReplay, F(STR_AUTOTEMP));
+      SERIAL_ECHOLNPGM("  M104"
+        " S", thermalManager.autotemp.cfg.min,
+        " B", thermalManager.autotemp.cfg.max,
+        " F", thermalManager.autotemp.cfg.factor
+      );
+  }
+#endif
+
 #endif // HAS_HOTEND
diff --git a/Marlin/src/lcd/menu/menu_advanced.cpp b/Marlin/src/lcd/menu/menu_advanced.cpp
index fbd07cc549..07516205ff 100644
--- a/Marlin/src/lcd/menu/menu_advanced.cpp
+++ b/Marlin/src/lcd/menu/menu_advanced.cpp
@@ -325,9 +325,9 @@ void menu_backlash();
     // Autotemp, Min, Max, Fact
     //
     #if ALL(AUTOTEMP, HAS_TEMP_HOTEND)
-      EDIT_ITEM(int3, MSG_MIN, &planner.autotemp.min, 0, thermalManager.hotend_max_target(0));
-      EDIT_ITEM(int3, MSG_MAX, &planner.autotemp.max, 0, thermalManager.hotend_max_target(0));
-      EDIT_ITEM(float42_52, MSG_FACTOR, &planner.autotemp.factor, 0, 10);
+      EDIT_ITEM(int3, MSG_MIN, &thermalManager.autotemp.cfg.min, 0, thermalManager.hotend_max_target(0));
+      EDIT_ITEM(int3, MSG_MAX, &thermalManager.autotemp.cfg.max, 0, thermalManager.hotend_max_target(0));
+      EDIT_ITEM(float42_52, MSG_FACTOR, &thermalManager.autotemp.cfg.factor, 0, 10);
     #endif
 
     //
diff --git a/Marlin/src/lcd/menu/menu_temperature.cpp b/Marlin/src/lcd/menu/menu_temperature.cpp
index 14824ca6b4..14845f5253 100644
--- a/Marlin/src/lcd/menu/menu_temperature.cpp
+++ b/Marlin/src/lcd/menu/menu_temperature.cpp
@@ -154,7 +154,7 @@ void menu_temperature() {
     EDIT_ITEM_FAST(int3, MSG_NOZZLE, &editable.celsius, 0, thermalManager.hotend_max_target(0), []{ thermalManager.setTargetHotend(editable.celsius, 0); });
   #elif HAS_MULTI_HOTEND
     HOTEND_LOOP() {
-      editable.celsius = thermalManager.temp_hotend[e].target;
+      editable.celsius = thermalManager.degTargetHotend(e);
       EDIT_ITEM_FAST_N(int3, e, MSG_NOZZLE_N, &editable.celsius, 0, thermalManager.hotend_max_target(e), []{ thermalManager.setTargetHotend(editable.celsius, MenuItemBase::itemIndex); });
     }
   #endif
diff --git a/Marlin/src/lcd/menu/menu_tune.cpp b/Marlin/src/lcd/menu/menu_tune.cpp
index 18d52bb640..8b34b01612 100644
--- a/Marlin/src/lcd/menu/menu_tune.cpp
+++ b/Marlin/src/lcd/menu/menu_tune.cpp
@@ -125,10 +125,13 @@ void menu_tune() {
   // Nozzle [1-4]:
   //
   #if HOTENDS == 1
-    EDIT_ITEM_FAST(int3, MSG_NOZZLE, &thermalManager.temp_hotend[0].target, 0, thermalManager.hotend_max_target(0), []{ thermalManager.start_watching_hotend(0); });
+    editable.celsius = thermalManager.degTargetHotend(0);
+    EDIT_ITEM_FAST(int3, MSG_NOZZLE, &editable.celsius, 0, thermalManager.hotend_max_target(0), []{ thermalManager.setTargetHotend(editable.celsius, 0); });
   #elif HAS_MULTI_HOTEND
-    HOTEND_LOOP()
-      EDIT_ITEM_FAST_N(int3, e, MSG_NOZZLE_N, &thermalManager.temp_hotend[e].target, 0, thermalManager.hotend_max_target(e), []{ thermalManager.start_watching_hotend(MenuItemBase::itemIndex); });
+    HOTEND_LOOP() {
+      editable.celsius = thermalManager.degTargetHotend(e);
+      EDIT_ITEM_FAST_N(int3, e, MSG_NOZZLE_N, &editable.celsius, 0, thermalManager.hotend_max_target(e), []{ thermalManager.setTargetHotend(editable.celsius, MenuItemBase::itemIndex); });
+    }
   #endif
 
   #if ENABLED(SINGLENOZZLE_STANDBY_TEMP)
diff --git a/Marlin/src/lcd/tft/touch.cpp b/Marlin/src/lcd/tft/touch.cpp
index eb62caa273..cefd7cb779 100644
--- a/Marlin/src/lcd/tft/touch.cpp
+++ b/Marlin/src/lcd/tft/touch.cpp
@@ -236,9 +236,10 @@ void Touch::touch(touch_control_t * const control) {
           #if HAS_HOTEND
             #define HOTEND_HEATER(N) TERN0(HAS_MULTI_HOTEND, N)
             TERN_(HAS_MULTI_HOTEND, MenuItemBase::itemIndex = heater);
+            editable.celsius = thermalManager.degTargetHotend(HOTEND_HEATER(heater));
             MenuItem_int3::action(GET_TEXT_F(TERN(HAS_MULTI_HOTEND, MSG_NOZZLE_N, MSG_NOZZLE)),
-              &thermalManager.temp_hotend[HOTEND_HEATER(heater)].target, 0, thermalManager.hotend_max_target(HOTEND_HEATER(heater)),
-              []{ thermalManager.start_watching_hotend(HOTEND_HEATER(MenuItemBase::itemIndex)); }
+              &editable.celsius, 0, thermalManager.hotend_max_target(HOTEND_HEATER(heater)),
+              []{ thermalManager.setTargetHotend(editable.celsius, HOTEND_HEATER(MenuItemBase::itemIndex)); }
             );
           #endif
           break;
diff --git a/Marlin/src/module/planner.cpp b/Marlin/src/module/planner.cpp
index b4c53fab6b..6534425262 100644
--- a/Marlin/src/module/planner.cpp
+++ b/Marlin/src/module/planner.cpp
@@ -211,10 +211,6 @@ uint32_t Planner::max_acceleration_steps_per_s2[DISTINCT_AXES]; // (steps/s^2) D
   skew_factor_t Planner::skew_factor; // Initialized by settings.load
 #endif
 
-#if ENABLED(AUTOTEMP)
-  autotemp_t Planner::autotemp = { AUTOTEMP_MIN, AUTOTEMP_MAX, AUTOTEMP_FACTOR, false };
-#endif
-
 // private:
 
 xyze_long_t Planner::position{0};
@@ -1339,7 +1335,8 @@ void Planner::check_axes_activity() {
   //
   TERN_(HAS_TAIL_FAN_SPEED, if (fans_need_update) sync_fan_speeds(tail_fan_speed));
 
-  TERN_(AUTOTEMP, autotemp_task());
+  // Update hotend temperature based on extruder speed
+  TERN_(AUTOTEMP, thermalManager.autotemp_task());
 
   #if ENABLED(BARICUDA)
     TERN_(HAS_HEATER_1, hal.set_pwm_duty(pin_t(HEATER_1_PIN), tail_valve_pressure));
@@ -1349,51 +1346,7 @@ void Planner::check_axes_activity() {
 
 #if ENABLED(AUTOTEMP)
 
-  #if ENABLED(AUTOTEMP_PROPORTIONAL)
-    void Planner::_autotemp_update_from_hotend() {
-      const celsius_t target = thermalManager.degTargetHotend(active_extruder);
-      autotemp.min = target + AUTOTEMP_MIN_P;
-      autotemp.max = target + AUTOTEMP_MAX_P;
-    }
-  #endif
-
-  /**
-   * Called after changing tools to:
-   *  - Reset or re-apply the default proportional autotemp factor.
-   *  - Enable autotemp if the factor is non-zero.
-   */
-  void Planner::autotemp_update() {
-    _autotemp_update_from_hotend();
-    autotemp.factor = TERN0(AUTOTEMP_PROPORTIONAL, AUTOTEMP_FACTOR_P);
-    autotemp.enabled = autotemp.factor != 0;
-  }
-
-  /**
-   * Called by the M104/M109 commands after setting Hotend Temperature
-   */
-  void Planner::autotemp_M104_M109() {
-    _autotemp_update_from_hotend();
-
-    if (parser.seenval('S')) autotemp.min = parser.value_celsius();
-    if (parser.seenval('B')) autotemp.max = parser.value_celsius();
-
-    // When AUTOTEMP_PROPORTIONAL is enabled, F0 disables autotemp.
-    // Normally, leaving off F also disables autotemp.
-    autotemp.factor = parser.seen('F') ? parser.value_float() : TERN0(AUTOTEMP_PROPORTIONAL, AUTOTEMP_FACTOR_P);
-    autotemp.enabled = autotemp.factor != 0;
-  }
-
-  /**
-   * Called every so often to adjust the hotend target temperature
-   * based on the extrusion speed, which is calculated from the blocks
-   * currently in the planner.
-   */
-  void Planner::autotemp_task() {
-    static float oldt = 0.0f;
-
-    if (!autotemp.enabled) return;
-    if (thermalManager.degTargetHotend(active_extruder) < autotemp.min - 2) return; // Below the min?
-
+  float Planner::get_high_e_speed() {
     float high = 0.0f;
     for (uint8_t b = block_buffer_tail; b != block_buffer_head; b = next_block_index(b)) {
       const block_t * const block = &block_buffer[b];
@@ -1402,12 +1355,7 @@ void Planner::check_axes_activity() {
         NOLESS(high, se);
       }
     }
-
-    float t = autotemp.min + high * autotemp.factor;
-    LIMIT(t, autotemp.min, autotemp.max);
-    if (t < oldt) t = t * (1.0f - (AUTOTEMP_OLDWEIGHT)) + oldt * (AUTOTEMP_OLDWEIGHT);
-    oldt = t;
-    thermalManager.setTargetHotend(t, active_extruder);
+    return high;
   }
 
 #endif // AUTOTEMP
diff --git a/Marlin/src/module/planner.h b/Marlin/src/module/planner.h
index c001dadd66..14c83b0559 100644
--- a/Marlin/src/module/planner.h
+++ b/Marlin/src/module/planner.h
@@ -32,6 +32,8 @@
 
 #include "../MarlinCore.h"
 
+#include "temperature.h"
+
 #if ENABLED(JD_HANDLE_SMALL_SEGMENTS)
   // Enable this option for perfect accuracy but maximum
   // computation. Should be fine on ARM processors.
@@ -165,14 +167,6 @@ typedef struct {
 
 } block_flags_t;
 
-#if ENABLED(AUTOTEMP)
-  typedef struct {
-    celsius_t min, max;
-    float factor;
-    bool enabled;
-  } autotemp_t;
-#endif
-
 #if ENABLED(LASER_FEATURE)
 
   typedef struct {
@@ -679,6 +673,10 @@ class Planner {
     // Manage fans, paste pressure, etc.
     static void check_axes_activity();
 
+    #if ENABLED(AUTOTEMP)
+      static float get_high_e_speed();
+    #endif
+
     // Apply fan speeds
     #if HAS_FAN
       static void sync_fan_speeds(uint8_t (&fan_speed)[FAN_COUNT]);
@@ -1104,13 +1102,6 @@ class Planner {
       static void clear_block_buffer_runtime();
     #endif
 
-    #if ENABLED(AUTOTEMP)
-      static autotemp_t autotemp;
-      static void autotemp_update();
-      static void autotemp_M104_M109();
-      static void autotemp_task();
-    #endif
-
     #if HAS_LINEAR_E_JERK
       FORCE_INLINE static void recalculate_max_e_jerk() {
         const float prop = junction_deviation_mm * SQRT(0.5) / (1.0f - SQRT(0.5));
@@ -1121,14 +1112,6 @@ class Planner {
 
   private:
 
-    #if ENABLED(AUTOTEMP)
-      #if ENABLED(AUTOTEMP_PROPORTIONAL)
-        static void _autotemp_update_from_hotend();
-      #else
-        static void _autotemp_update_from_hotend() {}
-      #endif
-    #endif
-
     /**
      * Get the index of the next / previous block in the ring buffer
      */
diff --git a/Marlin/src/module/settings.cpp b/Marlin/src/module/settings.cpp
index 3414d322da..523a3767df 100644
--- a/Marlin/src/module/settings.cpp
+++ b/Marlin/src/module/settings.cpp
@@ -271,8 +271,7 @@ typedef struct SettingsDataStruct {
   // AUTOTEMP
   //
   #if ENABLED(AUTOTEMP)
-    celsius_t planner_autotemp_max, planner_autotemp_min;
-    float planner_autotemp_factor;
+    autotemp_cfg_t planner_autotemp_cfg;                // M104 S B F
   #endif
 
   //
@@ -1012,10 +1011,8 @@ void MarlinSettings::postprocess() {
     // AUTOTEMP
     //
     #if ENABLED(AUTOTEMP)
-      _FIELD_TEST(planner_autotemp_max);
-      EEPROM_WRITE(planner.autotemp.max);
-      EEPROM_WRITE(planner.autotemp.min);
-      EEPROM_WRITE(planner.autotemp.factor);
+      _FIELD_TEST(planner_autotemp_cfg);
+      EEPROM_WRITE(thermalManager.autotemp.cfg);
     #endif
 
     //
@@ -2066,9 +2063,8 @@ void MarlinSettings::postprocess() {
       // AUTOTEMP
       //
       #if ENABLED(AUTOTEMP)
-        EEPROM_READ(planner.autotemp.max);
-        EEPROM_READ(planner.autotemp.min);
-        EEPROM_READ(planner.autotemp.factor);
+        _FIELD_TEST(planner_autotemp_cfg);
+        EEPROM_READ(thermalManager.autotemp.cfg);
       #endif
 
       //
@@ -3450,11 +3446,7 @@ void MarlinSettings::reset() {
   //
   // AUTOTEMP
   //
-  #if ENABLED(AUTOTEMP)
-    planner.autotemp.max = AUTOTEMP_MAX;
-    planner.autotemp.min = AUTOTEMP_MIN;
-    planner.autotemp.factor = AUTOTEMP_FACTOR;
-  #endif
+  TERN_(AUTOTEMP, thermalManager.autotemp.reset());
 
   //
   // X Axis Twist Compensation
@@ -3853,6 +3845,11 @@ void MarlinSettings::reset() {
     #endif
     gcode.say_units(); // " (in/mm)"
 
+    //
+    // M104 settings for AUTOTEMP
+    //
+    TERN_(AUTOTEMP, gcode.M104_report());
+
     //
     // M149 Temperature units
     //
diff --git a/Marlin/src/module/temperature.cpp b/Marlin/src/module/temperature.cpp
index fa84cec25d..5d5ccd3e4d 100644
--- a/Marlin/src/module/temperature.cpp
+++ b/Marlin/src/module/temperature.cpp
@@ -389,6 +389,10 @@ PGMSTR(str_t_heating_failed, STR_T_HEATING_FAILED);
 
 #endif // HAS_HOTEND
 
+#if ENABLED(AUTOTEMP)
+  autotemp_t Temperature::autotemp;   // Initialized by settings.load
+#endif
+
 #if HAS_TEMP_REDUNDANT
   redundant_info_t Temperature::temp_redundant;
 #endif
@@ -3552,7 +3556,7 @@ void Temperature::init() {
 void Temperature::disable_all_heaters() {
 
   // Disable autotemp, unpause and reset everything
-  TERN_(AUTOTEMP, planner.autotemp.enabled = false);
+  TERN_(AUTOTEMP, autotemp.enabled = false);
   TERN_(PROBING_HEATERS_OFF, pause_heaters(false));
 
   #if HAS_HOTEND
@@ -3637,7 +3641,7 @@ void Temperature::disable_all_heaters() {
       singlenozzle_temp[old_tool] = temp_hotend[0].target;
       if (singlenozzle_temp[new_tool] && singlenozzle_temp[new_tool] != singlenozzle_temp[old_tool]) {
         setTargetHotend(singlenozzle_temp[new_tool], 0);
-        TERN_(AUTOTEMP, planner.autotemp_update());
+        TERN_(AUTOTEMP, autotemp_update());
         set_heating_message(0);
         (void)wait_for_hotend(0, false);  // Wait for heating or cooling
       }
@@ -4778,7 +4782,7 @@ void Temperature::isr() {
       OPTARG(G26_CLICK_CAN_CANCEL, const bool click_to_cancel/*=false*/)
     ) {
       #if ENABLED(AUTOTEMP)
-        REMEMBER(1, planner.autotemp.enabled, false);
+        REMEMBER(1, autotemp.enabled, false);
       #endif
 
       #if TEMP_RESIDENCY_TIME > 0
@@ -4911,6 +4915,58 @@ void Temperature::isr() {
 
   #endif // HAS_TEMP_HOTEND
 
+  #if ENABLED(AUTOTEMP)
+
+    void Temperature::_autotemp_update_from_hotend() {
+      TERN_(AUTOTEMP_PROPORTIONAL, autotemp.update(degTargetHotend(active_extruder)));
+    }
+
+    /**
+     * Called after changing tools to:
+     *  - Reset or re-apply the default proportional autotemp factor.
+     *  - Enable autotemp if the factor is non-zero.
+     */
+    void Temperature::autotemp_update() {
+      _autotemp_update_from_hotend();
+      autotemp.cfg.factor = TERN0(AUTOTEMP_PROPORTIONAL, AUTOTEMP_FACTOR_P);
+      autotemp.enabled = autotemp.cfg.factor != 0;
+    }
+
+    /**
+     * Called by the M104/M109 commands after setting Hotend Temperature
+     */
+    void Temperature::autotemp_M104_M109() {
+      _autotemp_update_from_hotend();
+
+      if (parser.seenval('S')) autotemp.cfg.min = parser.value_celsius();
+      if (parser.seenval('B')) autotemp.cfg.max = parser.value_celsius();
+
+      // When AUTOTEMP_PROPORTIONAL is enabled, F0 disables autotemp.
+      // Normally, leaving off F also disables autotemp.
+      autotemp.cfg.factor = parser.seen('F') ? parser.value_float() : TERN0(AUTOTEMP_PROPORTIONAL, AUTOTEMP_FACTOR_P);
+      autotemp.enabled = autotemp.cfg.factor != 0;
+    }
+
+    /**
+     * Called every so often to adjust the hotend target temperature
+     * based on the extrusion speed, which is calculated from the blocks
+     * currently in the planner.
+     */
+    void Temperature::autotemp_task() {
+      if (!autotemp.enabled) return;
+      if (degTargetHotend(active_extruder) < autotemp.cfg.min - 2) return; // Below the min?
+
+      // Get a highest target proportion greater than zero
+      float high = planner.get_high_e_speed();
+
+      // Calculate a new target, with weighted correction for a drop
+      float t = autotemp.calculate(high);
+
+      _setTargetHotend(t, active_extruder);
+    }
+
+  #endif // AUTOTEMP
+
   #if HAS_HEATED_BED
 
     #ifndef MIN_COOLING_SLOPE_DEG_BED
diff --git a/Marlin/src/module/temperature.h b/Marlin/src/module/temperature.h
index 92fae44deb..884a72646e 100644
--- a/Marlin/src/module/temperature.h
+++ b/Marlin/src/module/temperature.h
@@ -603,6 +603,41 @@ typedef struct { raw_adc_t raw_min, raw_max; celsius_t mintemp, maxtemp; } temp_
   #define HAS_FAN_LOGIC 1
 #endif
 
+#if ENABLED(AUTOTEMP)
+
+  typedef struct {
+    celsius_t min, max;
+    float factor;
+  } autotemp_cfg_t;
+
+  typedef struct {
+    autotemp_cfg_t cfg;
+    bool enabled;
+
+    void reset() {
+      cfg.min = AUTOTEMP_MIN;
+      cfg.max = AUTOTEMP_MAX;
+      cfg.factor = AUTOTEMP_FACTOR;
+      enabled = false;
+    }
+    #if ENABLED(AUTOTEMP_PROPORTIONAL)
+      void update(const celsius_t t) {
+        cfg.min = t + AUTOTEMP_MIN_P;
+        cfg.max = t + AUTOTEMP_MAX_P;
+      }
+    #endif
+    float calculate(const celsius_t high) {
+      static float oldt = 0;
+      float t = cfg.min + high * cfg.factor;
+      NOMORE(t, cfg.max);
+      if (t < oldt) t = t * (1.0f - (AUTOTEMP_OLDWEIGHT)) + oldt * (AUTOTEMP_OLDWEIGHT);
+      oldt = t;
+      return t;
+    }
+  } autotemp_t;
+
+#endif // AUTOTEMP
+
 class Temperature {
 
   public:
@@ -1001,6 +1036,10 @@ class Temperature {
 
     #if HAS_HOTEND
 
+      static void _setTargetHotend(const celsius_t celsius, const uint8_t E_NAME) {
+        temp_hotend[HOTEND_INDEX].target = _MIN(celsius, hotend_max_target(HOTEND_INDEX));
+      }
+
       static void setTargetHotend(const celsius_t celsius, const uint8_t E_NAME) {
         const uint8_t ee = HOTEND_INDEX;
         #if PREHEAT_TIME_HOTEND_MS > 0
@@ -1010,7 +1049,8 @@ class Temperature {
             start_hotend_preheat_time(ee);
         #endif
         TERN_(AUTO_POWER_CONTROL, if (celsius) powerManager.power_on());
-        temp_hotend[ee].target = _MIN(celsius, hotend_max_target(ee));
+        _setTargetHotend(celsius, ee);
+        TERN_(AUTOTEMP, autotemp.enabled = false);
         start_watching_hotend(ee);
       }
 
@@ -1052,6 +1092,13 @@ class Temperature {
 
     #endif // HAS_HOTEND
 
+    #if ENABLED(AUTOTEMP)
+      static autotemp_t autotemp;
+      static void autotemp_update();
+      static void autotemp_M104_M109();
+      static void autotemp_task();
+    #endif
+
     #if HAS_HEATED_BED
 
       #if ENABLED(SHOW_TEMP_ADC_VALUES)
@@ -1349,6 +1396,10 @@ class Temperature {
       return true;
     }
 
+    #if ENABLED(AUTOTEMP)
+      static void _autotemp_update_from_hotend();
+    #endif
+
     // MAX Thermocouples
     #if HAS_MAX_TC
       #define MAX_TC_COUNT TEMP_SENSOR_IS_MAX_TC(0) + TEMP_SENSOR_IS_MAX_TC(1) + TEMP_SENSOR_IS_MAX_TC(2) + TEMP_SENSOR_IS_MAX_TC(REDUNDANT)
diff --git a/Marlin/src/module/tool_change.cpp b/Marlin/src/module/tool_change.cpp
index baf4ad813e..85254ea598 100644
--- a/Marlin/src/module/tool_change.cpp
+++ b/Marlin/src/module/tool_change.cpp
@@ -1581,7 +1581,7 @@ void tool_change(const uint8_t new_tool, bool no_move/*=false*/) {
     // Migrate the temperature to the new hotend
     #if HAS_MULTI_HOTEND
       thermalManager.setTargetHotend(thermalManager.degTargetHotend(active_extruder), migration_extruder);
-      TERN_(AUTOTEMP, planner.autotemp_update());
+      TERN_(AUTOTEMP, thermalManager.autotemp_update());
       thermalManager.set_heating_message(0);
       thermalManager.wait_for_hotend(active_extruder);
     #endif
diff --git a/buildroot/tests/mega2560 b/buildroot/tests/mega2560
index befb17e1f7..f323602954 100755
--- a/buildroot/tests/mega2560
+++ b/buildroot/tests/mega2560
@@ -82,7 +82,7 @@ opt_set DEFAULT_AXIS_STEPS_PER_UNIT '{ 4000 }' \
         MANUAL_FEEDRATE '{ 4*60 }' \
         AXIS_RELATIVE_MODES '{ false }' \
         HOMING_BUMP_MM '{}' HOMING_BUMP_DIVISOR '{}' HOMING_FEEDRATE_MM_M '{}'
-opt_enable REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+opt_enable REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER AUTOTEMP AUTOTEMP_PROPORTIONAL
 opt_disable X_DRIVER_TYPE Y_DRIVER_TYPE Z_DRIVER_TYPE
 exec_test $1 $2 "E Axis Only | DOGM MarlinUI" "$3"