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Basic Specifications

As you can see in the table below, the fundamental requirements and capabilities jive nicely with the abilities of your Arduino micro-controller.

A word of warning –  There are some that sell this module that think it’s measurement range is from -200 to 1300 degrees F.  They’re wrong.  The MAX6675 chip measurement range is limited to what is detailed below:

TEMPERATURE RANGE NOTE:  It is true that MAXIM 6675 will read from zero to 1024 degrees C.  However, there is another limiting factor.   The K thermocouple will come with insulated wires and cable sheathing.   These too have temperature limits associated with them.  It is not unusual to have a sheathing on your thermocouple that fall below the range of the maxim chip.  Be careful here.

 MAX6675 Module Pin Outs

The pin-outs for this module are shown in the illustration below. Click on the image to make it larger.

These pins function as follows:

SO: The module’s serial output.   Your Arduino will read this output.

CS:  Chip Select.   Setting low, selects the Module and tells it to supply an output that is synchronize with a clock

SCK : The Serial Clock… an input from your Arduino.

VCC: 5V supply

GND:  Ground.

– (or Minus):   The K thermocouple minus input.

+ ( or Plus):  The K Thermocouple plus input.

IMPORTANT NOTE– Most K thermocouples come with a red lead and a yellow lead.  The red lead is normally your negative connection and the yellow lead is your positive.  That is industry standard.

That said, some of the suppliers for the module will in fact jack this up  and provide you a thermocouple with red indicating positive.

The way to know is if you increase the temperature at the thermocouple tip and the indication goes lower.

MAX6675 Arduino Thermocouple Module Schematic

This module is a duplicate of the what is offered in the datasheet as a sample circuit.  In fact, if you were so inclined, you could simply buy the MAX6675  and build your own thermocouple measuring circuit for a few bucks less.  (click to enlarge)

MAX6675 Arduino Tutorial

Get the MAX6675 Arduino Library

The Maxim 6675 library for your Arduino if freely available at GitHub.   You can get it here.

If you are unfamiliar with installing Arduino libraries, you can read this page.

Connect your Arduino to the Thermocouple Module

Pretty simple stuff.   Keep the note about the thermocouple polarity in mind as you make these connections. (click image to enlarge)

Copy and Paste the Arduino MAX6675 Sketch

// Sample Arduino MAX6675 Arduino Sketch

#include "max6675.h"

int ktcSO = 8;
int ktcCS = 9;
int ktcCLK = 10;

MAX6675 ktc(ktcCLK, ktcCS, ktcSO);

  
void setup() {
  Serial.begin(9600);
  // give the MAX a little time to settle
  delay(500);
}

void loop() {
  // basic readout test
  
   Serial.print("Deg C = "); 
   Serial.print(ktc.readCelsius());
   Serial.print("\t Deg F = ");
   Serial.println(ktc.readFahrenheit());
 
   delay(500);
}