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K-type Thermocouple

Posted by Chaparro1973 
K-type Thermocouple
April 11, 2017 05:20PM
Just bought this:

Using a Rumba Board with Marlin Firmware

Can someone help me setting it?
Re: K-type Thermocouple
April 11, 2017 09:26PM
Rumba has no support for directly connecting a Thermocouple, you need a thermocouple amplifier chip and feed the output into one of the ADC inputs, eg 'MAX31855 breakout'

product eg
Re: K-type Thermocouple
April 12, 2017 10:49AM
What do you think it's the best for me to buy, and can you help me on the connections and settings for marlin.
I forgot to mention, but i have dual extruder setup, both with k-type
Re: K-type Thermocouple
April 19, 2017 10:21AM
Not clear where you are and what your sources are. Plus you don't say what your extruder is but if you first look in marlin/configuration.h and scroll down to the the Thermal Settings section you will see along list of thermistors that are supported. I'd find a local/easy source of one that is on that list. It will be far cheaper to buy a couple of those than to get sense amplifiers for the thermocouples.
Re: K-type Thermocouple
April 25, 2017 01:00PM
Just bougth two External thermocouple board v1.0
After several searches made the conections as you can see on the attach.
In marlin set:
#define TEMP_SENSOR_0 -1
#define TEMP_SENSOR_1 -1

Pins used
+5v pin 2
Ground pin 4
Signal 1 pin 6
Signal 2 pin 5

First time i tried i got 300º for extruder 1 and 2

Changed in config_adv
#define TEMP_SENSOR_AD595_GAIN 0.1

tried and it reads 30º for both, but if i turn on any heater i don't get any changes on temperature.

Can someone help me on that.
I tried searching, but i can't find much information on this theme
open | download - ligacoes.jpg (39.5 KB)
Re: K-type Thermocouple
April 26, 2017 07:16AM
Looking at the circuit of the rumba, EXP3 pins 5 & 6 are pwm outputs.

I think EXP3 pins 7 & 8 are what you need to connect the signals to as these are ADC 9 & 10 inputs.
Re: K-type Thermocouple
April 27, 2017 04:32PM
Managed to get it wright at last, thanks for your suport carl_m1968

Here are my conetions:

Changes made on Marlin

#define TEMP_SENSOR_0 -1
#define TEMP_SENSOR_1 -1


// Temperature Sensors
#if TEMP_SENSOR_0 == -1
#define TEMP_0_PIN 10 // Analog Input (connector *K1* on RUMBA thermocouple ADD ON is used)
#define TEMP_0_PIN 15 // Analog Input (default connector for thermistor *T0* on rumba board is used)

#if TEMP_SENSOR_1 == -1
#define TEMP_1_PIN 9 // Analog Input (connector *K2* on RUMBA thermocouple ADD ON is used)
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