Added CONTROLLERFAN. (Controlling a fan to cool down the steppper drivers)

Marlin/Configuration_adv.h

 #define TEMP_SENSOR_AD595_OFFSET 0.0
 #define TEMP_SENSOR_AD595_GAIN   1.0
 
+//This is for controlling a fan to cool down the stepper drivers
+//it will turn on when any driver is enabled
+//and turn off after the set amount of seconds from last driver being disabled again
+//#define CONTROLLERFAN_PIN 23 //Pin used for the fan to cool controller, comment out to disable this function
+#define CONTROLLERFAN_SEC 60 //How many seconds, after all motors were disabled, the fan should run
+
 //===========================================================================
 //=============================Mechanical Settings===========================
 //===========================================================================

Marlin/Marlin.pde

     axis_steps_per_sqr_second[i] = max_acceleration_units_per_sq_second[i] * axis_steps_per_unit[i];
   }
 
+
   tp_init();    // Initialize temperature loop 
   plan_init();  // Initialize planner;
   st_init();    // Initialize stepper;
   previous_millis_cmd = millis();
 }
 
+#ifdef CONTROLLERFAN_PIN
+unsigned long lastMotor = 0; //Save the time for when a motor was turned on last
+unsigned long lastMotorCheck = 0;
+
+void controllerFan()
+{
+  if ((millis() - lastMotorCheck) >= 2500) //Not a time critical function, so we only check every 2500ms
+  {
+    lastMotorCheck = millis();
+    
+    if(!READ(X_ENABLE_PIN) || !READ(Y_ENABLE_PIN) || !READ(Z_ENABLE_PIN)
+    #if EXTRUDERS > 2
+       || !READ(E2_ENABLE_PIN)
+    #endif
+    #if EXTRUDER > 1
+       || !READ(E2_ENABLE_PIN)
+    #endif
+       || !READ(E0_ENABLE_PIN)) //If any of the drivers are enabled...    
+    {
+      lastMotor = millis(); //... set time to NOW so the fan will turn on
+    }
+    
+    if ((millis() - lastMotor) >= (CONTROLLERFAN_SEC*1000UL) || lastMotor == 0) //If the last time any driver was enabled, is longer since than CONTROLLERSEC...   
+    {
+      WRITE(CONTROLLERFAN_PIN, LOW); //... turn the fan off
+    }
+    else
+    {
+      WRITE(CONTROLLERFAN_PIN, HIGH); //... turn the fan on
+    }
+  }
+}
+#endif
+
 void manage_inactivity(byte debug) 
 { 
   if( (millis() - previous_millis_cmd) >  max_inactive_time ) 
       }
     }
   }
+  #ifdef CONTROLLERFAN_PIN
+    controllerFan(); //Check if fan should be turned on to cool stepper drivers down
+  #endif
   #ifdef EXTRUDER_RUNOUT_PREVENT
     if( (millis() - previous_millis_cmd) >  EXTRUDER_RUNOUT_SECONDS*1000 ) 
     if(degHotend(active_extruder)>EXTRUDER_RUNOUT_MINTEMP)

Marlin/stepper.cpp

   //Initialize Step Pins
   #if (X_STEP_PIN > -1) 
     SET_OUTPUT(X_STEP_PIN);
+    if(!X_ENABLE_ON) WRITE(X_ENABLE_PIN,HIGH);
   #endif  
   #if (Y_STEP_PIN > -1) 
     SET_OUTPUT(Y_STEP_PIN);
+    if(!Y_ENABLE_ON) WRITE(Y_ENABLE_PIN,HIGH);
   #endif  
   #if (Z_STEP_PIN > -1) 
     SET_OUTPUT(Z_STEP_PIN);
+    if(!Z_ENABLE_ON) WRITE(Z_ENABLE_PIN,HIGH);
   #endif  
   #if (E0_STEP_PIN > -1) 
     SET_OUTPUT(E0_STEP_PIN);
+    if(!E_ENABLE_ON) WRITE(E0_ENABLE_PIN,HIGH);
   #endif  
   #if defined(E1_STEP_PIN) && (E1_STEP_PIN > -1) 
     SET_OUTPUT(E1_STEP_PIN);
+    if(!E_ENABLE_ON) WRITE(E1_ENABLE_PIN,HIGH);
   #endif  
   #if defined(E2_STEP_PIN) && (E2_STEP_PIN > -1) 
     SET_OUTPUT(E2_STEP_PIN);
+    if(!E_ENABLE_ON) WRITE(E2_ENABLE_PIN,HIGH);
   #endif  
 
+  #ifdef CONTROLLERFAN_PIN
+    SET_OUTPUT(CONTROLLERFAN_PIN); //Set pin used for driver cooling fan
+  #endif
+  
   // waveform generation = 0100 = CTC
   TCCR1B &= ~(1<<WGM13);
   TCCR1B |=  (1<<WGM12);