Hi all,

I have a Traeger meat probe that has a 1000Ω RTD in it that I want to hook up to an AtMega328P to show on an LCD screen. I see many circuits out there, like the MAX31865 and others from Adafruit, but I got to thinking, couldn't I just use the RTD as one half of a voltage divider and just use a precise power supply to make sure the power is always 5.00V ± 0.1V?

Thanks and stay safe,
Joe

 

I think you want to use a current source, not a voltage source. You want the same current going through the RTD as goes through your reference resistor. Having a known reference resistor with the same current going through it is really handy. You can use a differential A/D converter to measure the fixed resistor and the RTD. Then you can do any correction and linearization in the uC.

Here is an Analog Devices App Note on the subject

https://www.analog.com/media/en/technical-documentation/application-notes/AN-0970.pdf