Introduction: K-type Arduino Thermometer
Hi all,
Recently I had to measure the temperature in a place where ordinary temp sensors like LM35 or TMP36 wouldn't fit. And not only this but the temperature was many degrees below zero. To be precise -70c to -80c. Traditional sensors are not working below -50c so the solution I came up was to use a k-type thermocouple. In order to make arduino read the k-type thermocouple values I had to use a Thermocouple-to-Digital Converter. Thankfully Adafruit is selling MAX31855 in good price and also you can download an Arduino library from them. What more can you ask?
Step 1: Schematic
The schematic of the circuit is very simple. As you can see the Max31855 except the volt and ground has three more pins. The DO, the CS and CLK. I connected those to Arduino D5,D4 and D3 respectively. Then the only thing that was left was to connect the LCD. As you can see in the schematic LCD uses 6 pins from Arduino. For the lcd i used the LiquidCrystal library which comes with the Arduino IDE, so no need to download.
Step 2: Arduino Code
Last step was to upload the code to Arduino. Code is available here. All went smooth and temperature showed up to the lcd.
Here is a small video:
Thanks for reading and good luck!
10 Comments
6 years ago
Hi, how do I change celcuis to fahenheit using the file downloaded for your link to GitHub?
Reply 4 years ago
You can change the line:
double c = thermocouple.readCelsius();
to
double c = thermocouple.readFahrenheit();
Hope that helps.
Ref:
https://learn.adafruit.com/thermocouple/arduino-code
6 years ago
Thanks for sharing. You stated that you had success reading down to -80 deg C... Do you know if the Arduino is able to support the full range of the type K thermocouple (which I believe goes up to from -200 deg C to 1260 deg C)?
Many thanks!
Reply 6 years ago
Hi,
I don't see why it can't read down to -196. Arduino acts like the middle man between the Max31855 and the display. Good luck!
7 years ago
Sorry guys, some issues with azure. Link is up.
http://www.devacron.com/k-type-thermometer-lcd-arduino-nano/
Reply 7 years ago
Thanks you for sharing your project! I am having an accuracy issues, in a 70 degree F room the thermocouple is reading around 107 degrees, and I did change read celsuis to read farenheight. Thanks in advance.
Reply 6 years ago
I'm having the same issue. Did you find a fix?
7 years ago on Introduction
The code as found in Google cached page:
(http://webcache.googleusercontent.com/search?q=cache:qrqakUdqLtQJ:www.devacron.com/k-type-thermometer-lcd-arduino-nano/+&cd=1&hl=el&ct=clnk&gl=gr)
And the Arduino code which is making use of library Adafruit-MAX31855-library
7 years ago on Introduction
Hi,
the link for the code is broken
7 years ago on Introduction
Would it be possible to increase the number of inputs to 4 on this project? I understand I'd need separate ADC for each thermocouple but how would I then interface these with the Arduino so the display shows T1: T2: etc etc?
Cheers