From 73344e69c1cd361164aa67af9ab28344f17a1227 Mon Sep 17 00:00:00 2001
From: Daid <daid303@gmail.com>
Date: Thu, 16 Feb 2012 11:03:41 +0100
Subject: [PATCH] Added temperature offset/gain settings for AD595.

---
 Marlin/Configuration.h | 6 ++++++
 Marlin/temperature.cpp | 8 ++++----
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/Marlin/Configuration.h b/Marlin/Configuration.h
index f0d8913631..eed1895d4f 100644
--- a/Marlin/Configuration.h
+++ b/Marlin/Configuration.h
@@ -66,6 +66,12 @@
 #define HEATER_2_MAXTEMP 275
 #define BED_MAXTEMP 150
 
+//These defines help to calibrate the AD595 sensor in case you get wrong temperature measurements.
+//The measured temperature is defined as "actualTemp = (measuredTemp * TEMP_SENSOR_AD595_GAIN) + TEMP_SENSOR_AD595_OFFSET"
+#define TEMP_SENSOR_AD595_OFFSET 0.0
+#define TEMP_SENSOR_AD595_GAIN   1.0
+
+
 // PID settings:
 // Comment the following line to disable PID and enable bang-bang.
 #define PIDTEMP
diff --git a/Marlin/temperature.cpp b/Marlin/temperature.cpp
index 2f3888c018..9103127f70 100644
--- a/Marlin/temperature.cpp
+++ b/Marlin/temperature.cpp
@@ -312,7 +312,7 @@ int temp2analog(int celsius, uint8_t e) {
 
     return (1023 * OVERSAMPLENR) - raw;
   }
-  return celsius * (1024.0 / (5.0 * 100.0) ) * OVERSAMPLENR;
+  return ((celsius-TEMP_SENSOR_AD595_OFFSET)/TEMP_SENSOR_AD595_GAIN) * (1024.0 / (5.0 * 100.0) ) * OVERSAMPLENR;
 }
 
 // Takes bed temperature value as input and returns corresponding raw value. 
@@ -342,7 +342,7 @@ int temp2analogBed(int celsius) {
 
     return (1023 * OVERSAMPLENR) - raw;
 #elif defined BED_USES_AD595
-    return lround(celsius * (1024.0 * OVERSAMPLENR/ (5.0 * 100.0) ) );
+    return lround(((celsius-TEMP_SENSOR_AD595_OFFSET)/TEMP_SENSOR_AD595_GAIN) * (1024.0 * OVERSAMPLENR/ (5.0 * 100.0) ) );
 #else
     #warning No heater-type defined for the bed.
     return 0;
@@ -390,7 +390,7 @@ float analog2temp(int raw, uint8_t e) {
 
     return celsius;
   }
-  return raw * ((5.0 * 100.0) / 1024.0) / OVERSAMPLENR;
+  return ((raw * ((5.0 * 100.0) / 1024.0) / OVERSAMPLENR) * TEMP_SENSOR_AD595_GAIN) + TEMP_SENSOR_AD595_OFFSET;
 }
 
 // Derived from RepRap FiveD extruder::getTemperature()
@@ -421,7 +421,7 @@ float analog2tempBed(int raw) {
     return celsius;
     
   #elif defined BED_USES_AD595
-    return raw * ((5.0 * 100.0) / 1024.0) / OVERSAMPLENR;
+    return ((raw * ((5.0 * 100.0) / 1024.0) / OVERSAMPLENR) * TEMP_SENSOR_AD595_GAIN) + TEMP_SENSOR_AD595_OFFSET;
   #else
     #warning No heater-type defined for the bed.
   #endif