How to connect two PT100 to Raspberry pi?

Andrew asked Sep 11,2020
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How to properly connect two PT100 (or similar) temp sensors to raspberry pi. I have been googling and found MAX31865 converter but is it the best option? If im not mistaken both sensors would need own MAX31865 converter?  Suggestions for  what parts to use. Thanks

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    From my reading it seems that a PT100 is basically a variable resistor. And so, all you need to do is to measure resistance with very high accuracy. The first idea that comes to mind is a Whetstone bridge or an RC circuit. Information from those can be measured with any ADC. At that point throwing in the MAX chip and not worrying about implementing either of the two correctly might be worth it. You are correct that one MAX31865 handles one sensor. However, you could use an analog switch in your frontend, so you need only a single measuring element. We are talking about something like this: https://lcsc.com/product-detail/Others_Will-Semicon-WAS4728Q-10-TR_C239815.html It does add some resistance, so be sure to calibrate for it.

    Sep 11,20201 Comments
    Andrew 2020-09-14 09:49:43Reply

    Thank you so much!

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