Guide for thermocouple support for X3 and X3 PRO
X3 PRO includes 2 thermocouple inputs while it is optional on the X3 ( 2 inputs on the cover). Both are using the AD8495 thermocouple chip from Analog Devices. Use type-K Thermocouples.
How to check if you have an X3 cover with thermocouple support.
Remove X3 cover and look at the parts on the bottom. If you find these 2 chips as shown on the picture (red circles) then you can use the thermocouple inputs.
Connect the thermocouple (K-Type) wire to TC1 as shown on X3 cover.
TC1 on X3 PRO
Edit Marlin firmware to support thermocouples.
This guide was picked up from a post in the reprap forums here. Solution by cncjoe.
1. Open marlin in Arduino IDE. On the Configuration.h tab, use -1 to set your TEMP_SENSOR. The -1 setting is for AD595 thermocouple chip, which is similar to the AD8495 chip on the X3 and X3 PRO. Modify the temp sensor setting you want to use,.
#define TEMP_SENSOR_0 -1
2. On the Configuration_adv.h tab and look for the line "#define TEMP_SENSOR_AD595_GAIN 1.0" and replace the "1.0" with 2.0 as shown below.
#define TEMP_SENSOR_AD595_GAIN 2.0
3. Go to the Pin.h to edit the pin for TEMP_PIN. Locate the line that corresponds to the TEMP_SENSOR you want to use and replace it with the TC1 Analog pin number.
Analog pin numbers on X3: TC1=11 and TC2=4
Analog pin numbers on X3 PRO: TC1=4 and TC2=5
#define TEMP_0_PIN 11 // ANALOG NUMBERING
Upload firmware and this should get the thermocouple working.
The examples shown are for the Hotend, if using thermocouple for heat bed edit TEMP_BED_PIN and TEMP_SENSOR_BED instead.
NOTE: Thermocouple wires are polarized, reverse wires if temp readings are going the opposite or if having weird readings.