MAX31855K Thermocouple Breakout Hookup Guide

Contributors: .Brent.
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The MAX31855K Thermocouple Breakout is a simple 14-bit resolution, SPI-compatible, serial interface thermocouple digitizer that makes reading a wide range of temperatures possible. We've broken this device out on a breakout board along with all the necessary componets to make using it a breeze!

MAX6675 Breakout

This breakout is designed to be used in conjunction with a k-type thermocouple such as this one shown below.

k-type thermocouple

SparkFun's type K thermocouple

In this tutorial we're going to get you familiar with the workings of the MAX31855K. We'll go over how to hook it up to a our 3.3V Arduino Pro Mini, but you can use this breakout board with nearly limitless other options. Anything that can communicate over SPI will do. It can be as 'simple' as a custom set of logic gates, most micros, or as complicated as yours server's motherboard. Make sure you are using 3.3V, or level shifting into the range 3.0V to 3.6V. We'll close the tutorial out with some example Arduino code.

Suggested Materials

To follow along with this tutorial, you'll need the following:

Arduino Pro Mini 328 - 3.3V/8MHz

Arduino Pro Mini 328 - 3.3V/8MHz

SparkFun FTDI Basic Breakout - 3.3V

SparkFun FTDI Basic Breakout - 3.3V

Thermocouple Type-K - Glass Braid Insulated (Bare Wire)

Thermocouple Type-K - Glass Braid Insulated (Bare Wire)

SparkFun Thermocouple Breakout - MAX31855K

SparkFun Thermocouple Breakout - MAX31855K


Alternatively, you may use this thermocouple probe in conjunction with the thermocouple connector

Thermocouple Connector - PCC-SMP-K

Thermocouple Type-K - Stainless Steel

Thermocouple Type-K - Stainless Steel


To connect the breakout to the microcontroller, you will likely want some male headers, or you could use a few pieces of wire.

Additionally, you may want the following:


In order to get a good, solid, electrically-sound connection to the breakout boards, you'll need to solder to the pins. That means you'll need at least a basic soldering iron as well as solder. Check out our how to solder tutorial for help, if this is you first time soldering.

You will also need the following supplies, but very well might already have them, or something equivalent laying around:

Wire Strippers - 22-30AWG

4 Retired
Flush Cutters - Xcelite

Flush Cutters - Xcelite

Solder Lead Free - 15-gram Tube

Solder Lead Free - 15-gram Tube

Soldering Iron - 30W (US, 110V)

Soldering Iron - 30W (US, 110V)


Suggested Reading

These boards aren't too hard to use. If you've done anything with Arduino before, you'll be prepared to work with the MAX31855K. If you're not exactly sure what this "Arduino" thing is, or if you're not familiar with the topics below, consider reading their tutorials:

How to Solder: Through-Hole Soldering

This tutorial covers everything you need to know about through-hole soldering.

Serial Peripheral Interface (SPI)

SPI is commonly used to connect microcontrollers to peripherals such as sensors, shift registers, and SD cards.


Binary is the numeral system of electronics and it must be important to learn. But, what is binary? How does it translate to other numeral systems like decimal?

What is an Arduino?

What is this 'Arduino' thing anyway? This tutorials dives into what an Arduino is and along with Arduino projects and widgets.