2 wire RTD measurement

[rnmi_4774376]

Hi guy's,

     I want to measure the temp using 2 wire RTD, using Pt100 sensor. according to the code, I am getting negative and wrong temp. I analyzed the code then I realized that I am getting proper reading from ADC but because of lookup table I am getting wrong result. my ADC count be like for VRefHi = 8159, Vrtd  = 1624, Vreflo = 0 at 25°C. I don't know why I am not getting proper result. please guide me, where is the mistake. I attached code

Thanks.

[SampathS_11 · Accepted solution]

The resistance of the Pt100 turns out to be roughly 250Ω. This translates to -186° C. I think the reference resistor your are using may be around 250Ω. That is why we are getting Vrtd  = 1624. Kindly check the voltages V0, V1 and V2. If you are using a 100Ω reference resistor and Pt100 RTD, I expect to get Vrtd  ~ 4000.

Best regards,

Sampath Selvaraj