Added support for AD8495 K-type thermocouple amplifier

Requires removal of 4.7k pull resistor on sense pins.
Supports AD8495 amplifier board WITHOUT 1.25V on reference pin
(ie. TriangleLab's sensor and not Adafruit's breakout board)

Firmware/Configuration_adv.h

@@ -40,6 +40,11 @@
 #define TEMP_SENSOR_AD595_OFFSET 0.0
 #define TEMP_SENSOR_AD595_GAIN   1.0
 
+//These defines help to calibrate the AD8495 sensor in case you get wrong temperature measurements.
+//The measured temperature is defined as "actualTemp = (measuredTemp * TEMP_SENSOR_AD8495_GAIN) + TEMP_SENSOR_AD8495_OFFSET"
+#define TEMP_SENSOR_AD8495_OFFSET 0.0
+#define TEMP_SENSOR_AD8495_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
@@ -430,6 +435,15 @@ const unsigned int dropsegments=5; //everything with less than this number of st
 #if TEMP_SENSOR_0 == -2
   #define HEATER_0_USES_MAX6675
 #endif
+#if TEMP_SENSOR_0 == -4
+  #define HEATER_0_USES_AD8495
+#endif
+#if TEMP_SENSOR_1 == -4
+  #define HEATER_1_USES_AD8495
+#endif
+#if TEMP_SENSOR_2 == -4
+  #define HEATER_2_USES_AD8495
+#endif
 #if TEMP_SENSOR_0 == 0
   #undef HEATER_0_MINTEMP
   #undef HEATER_0_MAXTEMP

Firmware/temperature.cpp

@@ -948,7 +948,11 @@ static float analog2temp(int raw, uint8_t e) {
 
     return celsius;
   }
+#if defined(HEATER_0_USES_AD595)
   return ((raw * ((5.0 * 100.0) / 1024.0) / OVERSAMPLENR) * TEMP_SENSOR_AD595_GAIN) + TEMP_SENSOR_AD595_OFFSET;
+#elif defined (HEATER_0_USES_AD8495)
+  return ((raw * 5.0 / 1024.0 / OVERSAMPLENR) / 0.005 * TEMP_SENSOR_AD8495_GAIN) + TEMP_SENSOR_AD8495_OFFSET; //for 5V 10bit ADC
+#endif
 }
 
 // Derived from RepRap FiveD extruder::getTemperature()

Firmware/variants/1_75mm_MK3S-EINSy10a-E3Dv6full.h

@@ -31,10 +31,11 @@
 
 
 // Uncomment the below for the E3D PT100 temperature sensor (with or without PT100 Amplifier)
-#define E3D_PT100_EXTRUDER_WITH_AMP
+//#define E3D_PT100_EXTRUDER_WITH_AMP
 //#define E3D_PT100_EXTRUDER_NO_AMP
 //#define E3D_PT100_BED_WITH_AMP
 //#define E3D_PT100_BED_NO_AMP
+#define E3D_AD8495_EXTRUDER_WITH_AMP
 
 
 /*------------------------------------
@@ -325,7 +326,7 @@
 #define AMBIENT_MINTEMP -30
 
 // Maxtemps
-#if defined(E3D_PT100_EXTRUDER_WITH_AMP) || defined(E3D_PT100_EXTRUDER_NO_AMP)
+#if defined(E3D_PT100_EXTRUDER_WITH_AMP) || defined(E3D_PT100_EXTRUDER_NO_AMP) || defined(E3D_AD8495_EXTRUDER_WITH_AMP)
 #define HEATER_0_MAXTEMP 410
 #else
 #define HEATER_0_MAXTEMP 305
@@ -335,7 +336,7 @@
 #define BED_MAXTEMP 125
 #define AMBIENT_MAXTEMP 100
 
-#if defined(E3D_PT100_EXTRUDER_WITH_AMP) || defined(E3D_PT100_EXTRUDER_NO_AMP)
+#if defined(E3D_PT100_EXTRUDER_WITH_AMP) || defined(E3D_PT100_EXTRUDER_NO_AMP) || defined(E3D_AD8495_EXTRUDER_WITH_AMP)
 // Define PID constants for extruder with PT100
 #define  DEFAULT_Kp 21.70
 #define  DEFAULT_Ki 1.60
@@ -556,6 +557,7 @@
 //// Temperature sensor settings:
 // -2 is thermocouple with MAX6675 (only for sensor 0)
 // -1 is thermocouple with AD595
+// -4 is thermocouple with AD8495 (4.7k pullup removed)
 // 0 is not used
 // 1 is 100k thermistor - best choice for EPCOS 100k (4.7k pullup)
 // 2 is 200k thermistor - ATC Semitec 204GT-2 (4.7k pullup)
@@ -591,6 +593,8 @@
 #define TEMP_SENSOR_0 247
 #elif defined(E3D_PT100_EXTRUDER_NO_AMP)
 #define TEMP_SENSOR_0 148
+#elif defined(E3D_AD8495_EXTRUDER_WITH_AMP)
+#define TEMP_SENSOR_0 -4
 #else
 #define TEMP_SENSOR_0 5
 #endif