Add HAL-based thermal protection grace period for all heaters (#13778)

Marlin/src/HAL/HAL_LPC1768/HAL.h

@@ -147,6 +147,9 @@ using FilteredADC = LPC176x::ADC<ADC_LOWPASS_K_VALUE, ADC_MEDIAN_FILTER_SIZE>;
 #define HAL_READ_ADC()         FilteredADC::get_result()
 #define HAL_ADC_READY()        FilteredADC::finished_conversion()
 
+// A grace period for the ADC readings to stabilize before they start causing thermal protection errors.
+#define THERMAL_PROTECTION_GRACE_PERIOD 500
+
 // Parse a G-code word into a pin index
 int16_t PARSED_PIN_INDEX(const char code, const int16_t dval);
 // P0.6 thru P0.9 are for the onboard SD card

Marlin/src/module/temperature.cpp

@@ -944,13 +944,29 @@ void Temperature::manage_heater() {
     if (temp_hotend[1].current < MAX(HEATER_1_MINTEMP, HEATER_1_MAX6675_TMIN + .01)) min_temp_error(1);
   #endif
 
-  #if WATCH_HOTENDS || WATCH_BED || DISABLED(PIDTEMPBED) || HAS_AUTO_FAN || HEATER_IDLE_HANDLER || WATCH_CHAMBER
+  #define HAS_THERMAL_PROTECTION (ENABLED(THERMAL_PROTECTION_HOTENDS) || HAS_THERMALLY_PROTECTED_BED || ENABLED(THERMAL_PROTECTION_CHAMBER))
+
+  #if HAS_THERMAL_PROTECTION || DISABLED(PIDTEMPBED) || HAS_AUTO_FAN || HEATER_IDLE_HANDLER
     millis_t ms = millis();
   #endif
 
+  #if HAS_THERMAL_PROTECTION
+    #ifndef THERMAL_PROTECTION_GRACE_PERIOD
+      #define THERMAL_PROTECTION_GRACE_PERIOD 0 // No grace period needed on well-behaved boards
+    #endif
+    #if THERMAL_PROTECTION_GRACE_PERIOD > 0
+      static millis_t grace_period = ms + THERMAL_PROTECTION_GRACE_PERIOD;
+      if (ELAPSED(ms, grace_period)) grace_period = 0UL;
+    #else
+      static constexpr millis_t grace_period = 0UL;
+    #endif
+  #endif
+
   HOTEND_LOOP() {
-    if (degHotend(e) > temp_range[e].maxtemp)
+    #if ENABLED(THERMAL_PROTECTION_HOTENDS)
+      if (!grace_period && degHotend(e) > temp_range[e].maxtemp)
         _temp_error(e, PSTR(MSG_T_THERMAL_RUNAWAY), TEMP_ERR_PSTR(MSG_THERMAL_RUNAWAY, e));
+    #endif
 
     #if HEATER_IDLE_HANDLER
       hotend_idle[e].update(ms);
@@ -1003,8 +1019,10 @@ void Temperature::manage_heater() {
 
   #if HAS_HEATED_BED
 
-    if (degBed() > BED_MAXTEMP)
+    #if ENABLED(THERMAL_PROTECTION_BED)
+      if (!grace_period && degBed() > BED_MAXTEMP)
         _temp_error(-1, PSTR(MSG_T_THERMAL_RUNAWAY), TEMP_ERR_PSTR(MSG_THERMAL_RUNAWAY, -1));
+    #endif
 
     #if WATCH_BED
       // Make sure temperature is increasing
@@ -1076,8 +1094,10 @@ void Temperature::manage_heater() {
 
     #if HAS_HEATED_CHAMBER
 
-      if (degChamber() > CHAMBER_MAXTEMP)
+      #if ENABLED(THERMAL_PROTECTION_CHAMBER)
+        if (!grace_period && degChamber() > CHAMBER_MAXTEMP)
           _temp_error(-2, PSTR(MSG_T_THERMAL_RUNAWAY), TEMP_ERR_PSTR(MSG_THERMAL_RUNAWAY, -2));
+      #endif
 
       #if WATCH_CHAMBER
         // Make sure temperature is increasing
@@ -1610,7 +1630,7 @@ void Temperature::init() {
   }
 #endif
 
-#if ENABLED(THERMAL_PROTECTION_HOTENDS) || HAS_THERMALLY_PROTECTED_BED || ENABLED(THERMAL_PROTECTION_CHAMBER)
+#if HAS_THERMAL_PROTECTION
 
   #if ENABLED(THERMAL_PROTECTION_HOTENDS)
     Temperature::tr_state_machine_t Temperature::tr_state_machine[HOTENDS]; // = { { TRInactive, 0 } };
@@ -1637,7 +1657,7 @@ void Temperature::init() {
       else
         SERIAL_ECHOPAIR(" ;  Idle Timeout:", bed_idle.timed_out);
       SERIAL_EOL();
-    */
+    //*/
 
     const int heater_index = heater_id >= 0 ? heater_id : HOTENDS;