Two Thermocouples and Displays

Dear Community,

I'm totally new to microcontroller programming and working, so I hope you can help me.

I have two S-type thermocouples which measure temperatures in an apparatus. For working with this apparatus I need to see the temperatue of the thermocouples. For reading them I would like to use two MAX31855 and to display the values 7-segment displays (5-digits) would seem nice. After reading some post it seems that the MAX7221 would be feasible to use for each display.

The question I have is: Which Arduino do I need to get this working, or do I need two (one for each thermocouple and display)?

Thanks for your help,

Adafruit has the MAX31855: Thermocouple Amplifier MAX31855 breakout board (MAX6675 upgrade) : ID 269 : $14.95 : Adafruit Industries, Unique & fun DIY electronics and kits. The page has a note:

Hey we even have a handy tutorial on thermocouples which includes an Arduino library, wiring diagrams and example code. How easy is that?

That will answer the questions about the thermocouples - which pins are used, etc.

The MAX7221 is a serial device. You can use multiple instances of SoftwareSerial as long as you are writing only. I can’t image what you would want to read from a 7 segment display, so that doesn’t seem like a problem.

Any Arduino can be used. You only need one. Though for ease of construction, you might consider using two if they do not need to communicate with each other.

You can buy cheap MAX31855 sheilds from several places...

Likewise a 16x2 LCD

drivers for both are available to save a lot of hard work.

plug them together and write the code!



Thanks for the fast replies. Thats what I already thought, but needed to verified.

Then I will go on and first try it with two Arduinos, the only need is to display the temperature so communication is not necessary.

16x2 LCDs are considered not useful because the displays are placed a few meters away from the user so the readability is important.


If you use MAX31855 you will have to make sure you get the S-Type version.

Tom.... :slight_smile: