Arduino MAX6675 Thermocouple: Wiring, Code and Simulator

To build this Arduino MAX6675 Thermocouple project you need an Arduino Uno and a thermocouple MAX6675. The MAX6675 library reads a K-type thermocouple up to 1000 °C. Make the 5 connections in the wiring table, upload the Arduino C++ code, and move the Probe temperature slider: readings step in quarter degrees.

Open this circuit in the free Arduino Uno simulator

Parts list

Qty	Part	What it does
1	Arduino Uno	the microcontroller board
1	Thermocouple MAX6675	A K-type thermocouple amplifier on SPI (read-only): SO → MISO, CS, SCK. thermo.readCelsius() up to 1024 °C in 0.25 °C steps.

Wiring

#	From	To
1	Arduino Uno 5V	Thermocouple MAX6675 VCC
2	Arduino Uno GND	Thermocouple MAX6675 GND
3	Arduino Uno pin 6	Thermocouple MAX6675 SCK
4	Arduino Uno pin 5	Thermocouple MAX6675 CS
5	Arduino Uno pin 4	Thermocouple MAX6675 SO

Step by step

Open the simulator. Open the BitForBytes Embedded Lab in your browser and start from the Arduino Uno. No install or account is needed.
Add the parts. Add a thermocouple MAX6675 from the parts palette.
Wire 1. Connect Arduino Uno 5V to Thermocouple MAX6675 VCC.
Wire 2. Connect Arduino Uno GND to Thermocouple MAX6675 GND.
Wire 3. Connect Arduino Uno pin 6 to Thermocouple MAX6675 SCK.
Wire 4. Connect Arduino Uno pin 5 to Thermocouple MAX6675 CS.
Wire 5. Connect Arduino Uno pin 4 to Thermocouple MAX6675 SO.
Paste the Arduino C++ code. Paste the Arduino C++ code below into the code editor.
Run it. Press Run. Move the Probe temperature slider: readings step in quarter degrees.

Arduino C++ code

// MAX6675 library (Adafruit): a K-type thermocouple over software SPI.
// SCK 6, CS 5, SO 4.
#include <max6675.h>

MAX6675 thermocouple(6, 5, 4);

void setup() {
  Serial.begin(9600);
  delay(500);
}

void loop() {
  Serial.print("Probe: ");
  Serial.print(thermocouple.readCelsius(), 2);
  Serial.println(" C");
  delay(500);
}

What to try

Move the Probe temperature slider: readings step in quarter degrees.

Frequently asked questions

How do I wire the MAX6675 Thermocouple project on an Arduino Uno?

Make 5 connections: Arduino Uno 5V to Thermocouple MAX6675 VCC; Arduino Uno GND to Thermocouple MAX6675 GND; Arduino Uno pin 6 to Thermocouple MAX6675 SCK; Arduino Uno pin 5 to Thermocouple MAX6675 CS; Arduino Uno pin 4 to Thermocouple MAX6675 SO.

What parts do I need for this Arduino project?

An Arduino Uno and a thermocouple MAX6675.

Can I simulate this Arduino project online for free?

Yes. The BitForBytes Embedded Lab runs this exact circuit and Arduino C++ code in your browser for free, with no install and no hardware. The sketch is compiled with the real Arduino toolchain and runs on an emulated ATmega328P.

What does the code do?

The MAX6675 library reads a K-type thermocouple up to 1000 °C.