Fix for false detection of THERMAL RUNAWAY

The idea is that if it is detected that the extruder cannot keep the temperature, but well before reaching the alarm limit, the cooling fan is throttled. If that does not help, and the alarm limit is reached, the THERMAL RUNAWAY alarm is triggered as usual. This avoids the frustration of having large prints destroyed by a falsely detected thermal runaway when the only problem was that the cooling fan speed was set too high.
egilkv · Aug 7, 2019 · b91f3ff · b91f3ff
1 parent 61161b7
commit b91f3ff
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diff --git a/Firmware/Marlin.h b/Firmware/Marlin.h
@@ -260,6 +260,9 @@ extern float max_pos[3];
 extern bool axis_known_position[3];
 extern float zprobe_zoffset;
 extern int fanSpeed;
+#ifdef TEMP_RUNAWAY_SAFETY_NET
+extern unsigned char fanSpeedReduce;	// reduction of fan speed due to "safety net"
+#endif
 extern void homeaxis(int axis);
 
 

diff --git a/Firmware/Marlin_main.cpp b/Firmware/Marlin_main.cpp
@@ -320,6 +320,9 @@ float extruder_offset[NUM_EXTRUDER_OFFSETS][EXTRUDERS] = {
 
 uint8_t active_extruder = 0;
 int fanSpeed=0;
+#ifdef TEMP_RUNAWAY_SAFETY_NET
+unsigned char fanSpeedReduce=0; // reduction of fan speed due to "safety net"
+#endif
 
 #ifdef FWRETRACT
   bool autoretract_enabled=false;

diff --git a/Firmware/planner.cpp b/Firmware/planner.cpp
@@ -505,6 +505,10 @@ void check_axes_activity()
     disable_e1();
     disable_e2(); 
   }
+#ifdef TEMP_RUNAWAY_SAFETY_NET
+  if (tail_fan_speed >= fanSpeedReduce) tail_fan_speed -= fanSpeedReduce;
+  else tail_fan_speed = 0;
+#endif
 #if defined(FAN_PIN) && FAN_PIN > -1
 #ifdef FAN_KICK_START_TIME
 	static bool fan_kick = false;

diff --git a/Firmware/temperature.cpp b/Firmware/temperature.cpp
@@ -1136,6 +1136,9 @@ void temp_runaway_check(int _heater_id, float _target_temperature, float _curren
           {
                __hysteresis = TEMP_RUNAWAY_EXTRUDER_HYSTERESIS;
                __timeout = TEMP_RUNAWAY_EXTRUDER_TIMEOUT;
+#ifdef TEMP_RUNAWAY_SAFETY_NET
+               fanSpeedReduce = 0; // default assumption is no reduction in fan speed
+#endif
           }
 #endif
 
@@ -1215,6 +1218,30 @@ void temp_runaway_check(int _heater_id, float _target_temperature, float _curren
 
 		if (temp_runaway_check_active)
 		{			
+#if defined(TEMP_RUNAWAY_SAFETY_NET) && TEMP_RUNAWAY_SAFETY_NET < TEMP_RUNAWAY_EXTRUDER_HYSTERESIS
+		   if (!_isbed)
+		   {
+			   if (fanSpeed > 0 && _current_temperature < (_target_temperature - TEMP_RUNAWAY_SAFETY_NET))
+			 {
+			     // into safety net and beyond.
+			     // implement trivial P regulator of fan speed against temperature
+			     // over 60% of temperature span where runaway shutdown kicks in.
+			     // this will reduce actual filament temperature when this mechanism is triggered
+			     // which may happen to be not a bad thing for instance when bridging.
+			     int reduce = (255.0 * (_target_temperature - TEMP_RUNAWAY_SAFETY_NET - _current_temperature)) /
+						   (0.6 * (TEMP_RUNAWAY_EXTRUDER_HYSTERESIS - TEMP_RUNAWAY_SAFETY_NET));
+			     fanSpeedReduce = (reduce < 255) ? reduce : 255;
+#if 0 // DEBUG
+			     static unsigned char did_warn; // reset when?
+			     if (!did_warn)
+			     {
+				     LCD_ALERTMESSAGEPGM("FAN THROTTLED");
+				     did_warn = 1;
+			     }
+#endif
+			   }
+		   }
+#endif
 			//	we are in range
 			if ((_isbed && (_target_temperature > TEMP_MAX_CHECKED_BED) && (_current_temperature > TEMP_MAX_CHECKED_BED)) || ((_current_temperature > (_target_temperature - __hysteresis)) && (_current_temperature < (_target_temperature + __hysteresis))))
 			{
@@ -1324,6 +1351,10 @@ void disable_heater()
       WRITE(HEATER_BED_PIN,LOW);
     #endif
   #endif 
+
+  #ifdef TEMP_RUNAWAY_SAFETY_NET
+    fanSpeedReduce = 0;
+  #endif
 }
 
 void max_temp_error(uint8_t e) {

diff --git a/Firmware/ultralcd.cpp b/Firmware/ultralcd.cpp
@@ -4942,6 +4942,9 @@ void lcd_print_stop() {
 		SET_OUTPUT(FAN_PIN);
 		WRITE(FAN_PIN, 0);
 		fanSpeed=0;
+#ifdef TEMP_RUNAWAY_SAFETY_NET
+		fanSpeedReduce = 0;
+#endif
 }
 
 

diff --git a/Firmware/variants/1_75mm_MK1-RAMBo10a-E3Dv6full.h b/Firmware/variants/1_75mm_MK1-RAMBo10a-E3Dv6full.h
@@ -184,6 +184,7 @@ ADDITIONAL FEATURES SETTINGS
 #define TEMP_RUNAWAY_BED_HYSTERESIS 5
 #define TEMP_RUNAWAY_BED_TIMEOUT 360
 
+#define TEMP_RUNAWAY_SAFETY_NET 3 // temperature difference where "fan reduce safety net" feature kicks in
 #define TEMP_RUNAWAY_EXTRUDER_HYSTERESIS 15
 #define TEMP_RUNAWAY_EXTRUDER_TIMEOUT 45
 

diff --git a/Firmware/variants/1_75mm_MK1-RAMBo13a-E3Dv6full.h b/Firmware/variants/1_75mm_MK1-RAMBo13a-E3Dv6full.h
@@ -184,6 +184,7 @@ ADDITIONAL FEATURES SETTINGS
 #define TEMP_RUNAWAY_BED_HYSTERESIS 5
 #define TEMP_RUNAWAY_BED_TIMEOUT 360
 
+#define TEMP_RUNAWAY_SAFETY_NET 3 // temperature difference where "fan reduce safety net" feature kicks in
 #define TEMP_RUNAWAY_EXTRUDER_HYSTERESIS 15
 #define TEMP_RUNAWAY_EXTRUDER_TIMEOUT 45
 

diff --git a/Firmware/variants/1_75mm_MK2-MultiMaterial-RAMBo10a-E3Dv6full.h b/Firmware/variants/1_75mm_MK2-MultiMaterial-RAMBo10a-E3Dv6full.h
@@ -181,6 +181,7 @@ ADDITIONAL FEATURES SETTINGS
 #define TEMP_RUNAWAY_BED_HYSTERESIS 5
 #define TEMP_RUNAWAY_BED_TIMEOUT 360
 
+#define TEMP_RUNAWAY_SAFETY_NET 3 // temperature difference where "fan reduce safety net" feature kicks in
 #define TEMP_RUNAWAY_EXTRUDER_HYSTERESIS 15
 #define TEMP_RUNAWAY_EXTRUDER_TIMEOUT 45
 

diff --git a/Firmware/variants/1_75mm_MK2-MultiMaterial-RAMBo13a-E3Dv6full.h b/Firmware/variants/1_75mm_MK2-MultiMaterial-RAMBo13a-E3Dv6full.h
@@ -183,6 +183,7 @@ ADDITIONAL FEATURES SETTINGS
 #define TEMP_RUNAWAY_BED_HYSTERESIS 5
 #define TEMP_RUNAWAY_BED_TIMEOUT 360
 
+#define TEMP_RUNAWAY_SAFETY_NET 3 // temperature difference where "fan reduce safety net" feature kicks in
 #define TEMP_RUNAWAY_EXTRUDER_HYSTERESIS 15
 #define TEMP_RUNAWAY_EXTRUDER_TIMEOUT 45
 

diff --git a/Firmware/variants/1_75mm_MK2-RAMBo10a-E3Dv6full.h b/Firmware/variants/1_75mm_MK2-RAMBo10a-E3Dv6full.h
@@ -181,6 +181,7 @@ ADDITIONAL FEATURES SETTINGS
 #define TEMP_RUNAWAY_BED_HYSTERESIS 5
 #define TEMP_RUNAWAY_BED_TIMEOUT 360
 
+#define TEMP_RUNAWAY_SAFETY_NET 3 // temperature difference where "fan reduce safety net" feature kicks in
 #define TEMP_RUNAWAY_EXTRUDER_HYSTERESIS 15
 #define TEMP_RUNAWAY_EXTRUDER_TIMEOUT 45
 

diff --git a/Firmware/variants/1_75mm_MK2-RAMBo13a-E3Dv6full.h b/Firmware/variants/1_75mm_MK2-RAMBo13a-E3Dv6full.h
@@ -183,6 +183,7 @@ ADDITIONAL FEATURES SETTINGS
 #define TEMP_RUNAWAY_BED_HYSTERESIS 5
 #define TEMP_RUNAWAY_BED_TIMEOUT 360
 
+#define TEMP_RUNAWAY_SAFETY_NET 3 // temperature difference where "fan reduce safety net" feature kicks in
 #define TEMP_RUNAWAY_EXTRUDER_HYSTERESIS 15
 #define TEMP_RUNAWAY_EXTRUDER_TIMEOUT 45