PT100 temperature sensor with a RTD-to-Digital Converter (MAX31865)


I am attempting to use a PT100 temperature sensor with a RTD-to-Digital Converter (MAX31865) with my Arduino Uno, and I wasn’t sure how to go about hooking that up. The MAX31865 had a Serial Output pin, which I guess I would need to attach to my Arduino somewhere. I’m really new at this, so sorry if this is a dumb question.

Any help would be greatly appreciated,

The MAX31865 is an SPI chip, so you can connect it to the Arduino's SPI port.

SDI -> MOSI SDO -> MISO SCLK -> SCK CS -> any pin of your choosing.


Hello sir, i am doing the project of measuring temp. from rtd (2-wire) using arduino. i made the ckt as shown in the diagram in link but i did some changes in it such as i removed the part of MUX from it because i am using only one rtd sensor but i am not getting what changes should we do in that example program and rtd library. can you help me please. Thank you.

I have no idea what is in the example program or the library. Post what you have written and maybe we can make suggestions.

Also post your schematics unless they are exactly the same as the "AMPLIFIER STAGE" in that link.


hello rob,
I am really sorry for previous post. I have to measure the temperature using RTD(pt 100) (2 wire) sensor and arduino, first of all i make simple voltage divider circuit but i am not getting good resolution and the accuracy is about ± 3.07 degree C. Can you help me to improve the accuracy of reading please.

Sorry I have not used these sensors, but if you are only using a voltage divider why did you link to that opamp circuit?

I suspect that the range of the RTD is not enough to give you the resolution you want which is probably why that circuit has some gain and offset.