Merge pull request #17 from WebSpider/master

Add a maximum temperature limit after which the heater shuts down.

Tonokip_Firmware/Tonokip_Firmware.pde

@@ -140,6 +140,9 @@ float tt=0,bt=0;
 #ifdef MINTEMP
   int minttemp=temp2analog(MINTEMP);
 #endif
+#ifdef MAXTEMP
+int maxttemp=temp2analog(MAXTEMP);
+#endif
         
 //Inactivity shutdown variables
 unsigned long previous_millis_cmd=0;
@@ -1375,6 +1378,12 @@ inline void manage_heater()
     if(current_raw<=minttemp)
         target_raw=0;
   #endif
+  #ifdef MAXTEMP
+    if(current_raw>maxttemp) {
+        // We are too hot. Emergency brake to protect hotend
+        kill(5);
+    }
+  #endif
   #if (TEMP_0_PIN > -1) || defined (HEATER_USES_MAX66675)
     #ifdef PIDTEMP
       error = target_raw - current_raw;
@@ -1578,6 +1587,7 @@ inline void kill(byte debug)
       case 2: Serial.print("Linear Move Abort, Last Line: "); break;
       case 3: Serial.print("Homing X Min Stop Fail, Last Line: "); break;
       case 4: Serial.print("Homing Y Min Stop Fail, Last Line: "); break;
+      case 5: Serial.print("Hot-end overheat protection, Last Line: "); break;
     } 
     Serial.println(gcode_LastN);
     delay(5000); // 5 Second delay

Tonokip_Firmware/configuration.h

@@ -61,6 +61,12 @@ float min_constant_speed_units = 2; // the minimum units of an accelerated move
 //The minimal temperature defines the temperature below which the heater will not be enabled
 //#define MINTEMP 
 
+//Experimental max temp
+//When temperature exceeds max temp, your bot will halt.
+//This feature exists to protect your hotend from overheating accidentally, but *NOT* from thermistor short/failure!
+//You should use MINTEMP for thermistor short/failure protection.
+//#define MAXTEMP 275
+
 // Select one of these only to define how the nozzle temp is read.
 #define HEATER_USES_THERMISTOR
 //#define HEATER_USES_AD595