Thermocouple temp display on 7segment 4digit

Hi guys,

First of all, I have to warn you... Arduino and I, just met... so this is the definition of being a n00b right here. I don't know coding, but I want to learn.

My project description:

I'll stick a thermocouple inside my car's exhaust and I want to see the temperature displayed inside the cabin. What I have right now for this project:

Arduino Nano K-Type Thermocouple MAX6675 interface for the thermocouple 4 digits / 7 segments / 4 and 5 pins displays(I got different types, didn't know which one I'll use)

The 4 pins has: CLK / DIO The 5 pins has: SCKLK / RCLK / DIO

What I did so far: I got the MAX6675 library, modified it to transmit only Celsius on the Serial Read. And it works, I can see it in the Serial Monitor.

Aaaand now I'm stuck, because I have no idea on how to show the temperature on one of my 7segment display. I would like to show the temperature on the first three digits, and a simple, constant "C" on the last one. Like 355C

Any chance I could get some help with what I library I need for the displays, or how the rest of the code for this should look like?


// this example is public domain. enjoy!

#include "max6675.h"

int thermoDO = 4;
int thermoCS = 5;
int thermoCLK = 6;

MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);
int vccPin = 3;
int gndPin = 2;
void setup() {
  // use Arduino pins 
  pinMode(vccPin, OUTPUT); digitalWrite(vccPin, HIGH);
  pinMode(gndPin, OUTPUT); digitalWrite(gndPin, LOW);
  Serial.println("MAX6675 test");
  // wait for MAX chip to stabilize

void loop() {
  // basic readout test, just print the current temp
   Serial.print("C = "); 


Boggy: 4 digits / 7 segments / 4 and 5 pins displays(I got different types, didn't know which one I'll use)

The 4 pins has: CLK / DIO The 5 pins has: SCKLK / RCLK / DIO

Hi and welcome.

Can you post links to those displays? Hopefully there will be a data sheet, otherwise we'll have to try and guess how to use them. If not, close-up pics of the pins might help.

Sounds like they may have built-in drivers with a serial interface of some kind, but there are a few different kinds...


Hello Paul,

Thanks for your reply. Here are the eBay links for both.

4 pins / 5 pins

Maybe you guys can read into that "chinenglish" in the descriptions. I for one can't understand if the 5pin needs an extra microcontroller or not.

I did find this for TM1637, maybe it will help. I'm thinking this is the easiest to use of the two?

Key Features
-Use either raw segment values or decimal numbers (with and without leading zero)
-Set either the whole display or any digit independently
-Control the brightness
-Pure software implementation
CLK - Clock; connect to any digital pin on the Arduino
DIO - Data I/O; connect to any digital pin on the Arduino
When a TM1637Display object is created, the clock and data pin numbers are passed as arguments and get bound.

There's an Arduino library for TM1637. Looks reasonably easy to use.

The other display uses a couple of ordinary 595 shift registers, so the Arduino must perform the multiplexing. This is not a problem in the case of your project. Makes the sketch more complex, but you could learn more, about multiplexing etc.

So its up to you!