Monitoring a wood stove flue temp and capturing the data

[ISY4Me]

I do not know the precise answer, but from what I have read the thermocouple output is a very low voltage and the amp reads that signal and provides cold junction compensation and digitizes the output.  The output of the MAX31855 (MAX31856 can also be used) or the MAX6675 is then read by the RPi.

The hardware design is talked about on many sites and I took the recommendations from what I read.  The Maxim data sheet can explain more that I can...https://www.alldatasheet.com/datasheet-pdf/pdf/415787/MAXIM/MAX31855.html

[Guy Lavoie]

I see, it's an amplifier specifically designed for thermocouples. The output is SPI serial. I've done SPI with a 8051 microcontroller (showing my age!).