From b76a110336fd66b9da8da6aac704e408c676740d Mon Sep 17 00:00:00 2001
From: blddk <michael.andresen@gmail.com>
Date: Thu, 24 May 2012 21:13:49 +0300
Subject: Added function to turn a fan on and off to keep heat from the hotend
 to rise up into the extruder.

---
 Sprinter/heater.cpp | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/Sprinter/heater.cpp b/Sprinter/heater.cpp
index ebab2a5..69e9e86 100644
--- a/Sprinter/heater.cpp
+++ b/Sprinter/heater.cpp
@@ -32,6 +32,10 @@
   void controllerFan(void);
 #endif
 
+#ifdef EXTRUDERFAN_PIN
+  void extruderFan(void);
+#endif
+
 // Manage heater variables. For a thermistor or AD595 thermocouple, raw values refer to the 
 // reading from the analog pin. For a MAX6675 thermocouple, the raw value is the temperature in 0.25 
 // degree increments (i.e. 100=25 deg). 
@@ -734,6 +738,10 @@ void PID_autotune(int PIDAT_test_temp)
   controllerFan(); //Check if fan should be turned on to cool stepper drivers down
 #endif
 
+#ifdef EXTRUDERFAN_PIN
+  extruderFan(); //Check if fan should be turned on to cool extruder down
+#endif
+
 }
 
 #if defined (HEATER_USES_THERMISTOR) || defined (BED_USES_THERMISTOR)
@@ -844,3 +852,24 @@ void controllerFan()
 }
 #endif
 
+#ifdef EXTRUDERFAN_PIN
+unsigned long lastExtruderCheck = 0;
+
+void extruderFan()
+{
+  if ((millis() - lastExtruderCheck) >= 2500) //Not a time critical function, so we only check every 2500ms
+  {
+    lastExtruderCheck = millis();
+           
+    if (analog2temp(current_raw) < EXTRUDERFAN_DEC)
+    {
+      WRITE(EXTRUDERFAN_PIN, LOW); //... turn the fan off
+    }
+    else
+    {
+      WRITE(EXTRUDERFAN_PIN, HIGH); //... turn the fan on
+    }
+  }
+}
+#endif
+
-- 
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