heating up santity, formarly knows as "watchdog", but renamed due to the existance of the real watchdog, works now.

Marlin/Configuration.h

 
 #define BED_CHECK_INTERVAL 5000 //ms
 
-//// Experimental watchdog and minimal temp
-// The watchdog waits for the watchperiod in milliseconds whenever an M104 or M109 increases the target temperature
-// If the temperature has not increased at the end of that period, the target temperature is set to zero. It can be reset with another M104/M109
-/// CURRENTLY NOT IMPLEMENTED AND UNUSEABLE
-//#define WATCHPERIOD 5000 //5 seconds
+//// Heating sanity check:
+// This waits for the watchperiod in milliseconds whenever an M104 or M109 increases the target temperature
+// If the temperature has not increased at the end of that period, the target temperature is set to zero. 
+// It can be reset with another M104/M109
+//#define WATCHPERIOD 20000 //20 seconds
 
 // Actual temperature must be close to target for this long before M109 returns success
 //#define TEMP_RESIDENCY_TIME 20  // (seconds)

Marlin/temperature.cpp

 #endif //PIDTEMP
   
 #ifdef WATCHPERIOD
-  static int watch_raw[3] = {-1000,-1000,-1000};
+  static int watch_oldtemp[3] = {0,0,0};
   static unsigned long watchmillis = 0;
 #endif //WATCHPERIOD
 
       WRITE(HEATER_0_PIN,LOW);
     }    
   #endif
-    
+  
+  #ifdef WATCHPERIOD
+    if(watchmillis && millis() - watchmillis > WATCHPERIOD){
+        if(watch_oldtemp[TEMPSENSOR_HOTEND_0] >= degHotend(active_extruder)){
+            setTargetHotend(0,active_extruder);
+            LCD_MESSAGEPGM("Heating failed");
+            SERIAL_ECHO_START;
+            SERIAL_ECHOLN("Heating failed");
+        }else{
+            watchmillis = 0;
+        }
+    }
+  #endif
+  
   if(millis() - previous_millis_bed_heater < BED_CHECK_INTERVAL)
     return;
   previous_millis_bed_heater = millis();
   if(isHeatingHotend0())
   {
     watchmillis = max(1,millis());
-    watch_raw[TEMPSENSOR_HOTEND_0] = current_raw[TEMPSENSOR_HOTEND_0];
+    watch_oldtemp[TEMPSENSOR_HOTEND_0] = degHotend(0);
   }
   else
   {

Marlin/temperature.h

   extern float pid_setpoint ;
 #endif
   
-#ifdef WATCHPERIOD
-  extern int watch_raw[3] ;
-  extern unsigned long watchmillis;
-#endif
+// #ifdef WATCHPERIOD
+//   extern int watch_raw[3] ;
+//   extern unsigned long watchmillis;
+// #endif