Problems with MAX31855 and Thermocouple K-type

Other Hardware Sensors
1

Hallo all
I have a project where I need to read temperatures in a range of 50-220 degrees. I have tried to follow this guide but run into some problems with the monitor output.

The guide I been trying:

My Set up:
Arduino Uno R3 with MAX 31855 and a thermocouple K-type

The places I maybe think it could be is:

  • Wrong Thermocouple
  • Something wrong with the code
  • Bad soldering on the MAX31855, from when I put it together
  • Wrong set up on the breadboard/Uno

I am new to Arduino so would really like this to work.
Hope someone can see my error and help my fix it =)

The Code:

/*************************************************** 
  This is an example for the Adafruit Thermocouple Sensor w/MAX31855K

  Designed specifically to work with the Adafruit Thermocouple Sensor
  ----> https://www.adafruit.com/products/269

  These displays use SPI to communicate, 3 pins are required to  
  interface
  Adafruit invests time and resources providing this open source code, 
  please support Adafruit and open-source hardware by purchasing 
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.  
  BSD license, all text above must be included in any redistribution
 ****************************************************/

#include "Adafruit_MAX31855.h"

int thermoDO = 3;
int thermoCS = 4;
int thermoCLK = 5;

Adafruit_MAX31855 thermocouple(thermoCLK, thermoCS, thermoDO);
  
void setup() {
  Serial.begin(9600);
  
  Serial.println("MAX31855 test");
  // wait for MAX chip to stabilize
  delay(500);
}

void loop() {
  // basic readout test, just print the current temp
   Serial.print("Internal Temp = ");
   Serial.println(thermocouple.readInternal());

   double c = thermocouple.readCelsius();
   if (isnan(c)) {
     Serial.println("Something wrong with thermocouple!");
   } else {
     Serial.print("C = "); 
     Serial.println(c);
   }
   //Serial.print("F = ");
   //Serial.println(thermocouple.readFarenheit());
 
   delay(1000);
}

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2 
#include "Adafruit_MAX31855.h"

int thermoDO = 3;
int thermoCS = 4;
int thermoCLK = 5;

Adafruit_MAX31855 thermocouple(thermoCLK, thermoCS, thermoDO);

:): check your CLK and D0 connections..........pin numbers look reversed, either h/w or code, probably is of little consequence.

3

Try connecting 5V to the Vin pin on the breakout board. If the board has a 3.3V regulator as described, then 3.3V input may not be enough.

4

Damn guys this is awesome it works XD

Swapped the pinNumber on the DO and CLK, and change the power supply to 5V instead of 3V and it works. A newbie mistake with the pinNumber and a good reason not to works late night on this project, your stop thinking at some point :wink:
Thanks a lot, this really saved my day. :slight_smile:

The Code I change

#include "Adafruit_MAX31855.h"

int thermoDO = 5;
int thermoCS = 4;
int thermoCLK = 3;
5

Glad you got it working. Since there was a wiring error, I'd be curious to know if it still works if the breakout board is switched back to 3.3V.

6

Both 3.3V and 5V works so it was the wiring error. Still thanks a lot =)