PT 100 resistance measurement

[sandy.12345]

hello,
can any one tell me how to measure pt 100 resistance using atmega32 . i measured resistance by using th circuit https://obrazki.elektroda.pl/7415419300_1356333074.png but it jumps temperature from 27 to 30 ,30 to 33 please help me to make my first project success

 

[wp100]

Hi,

You cannot properly use a PT100 sensor like that, it must have an op amp circuit between it and the micro.
Just search this forum and the web for the many designs out there.

You can use that type of circuit if you use a NTC thermistor, they can be very accurate , I use them for resolutions down to 0.1c.

Consider many of the other types of popular and simpe to use sensors , such as LM34, LM35,DS18B20 which are also a lot cheaper.

 

[iukhan]

You will need a constant current source to measure resistance of PT100. See the application note https://ww1.microchip.com/downloads/en/appnotes/00687c.pdf

 

[jayanth.devarayanadurga]

https://www.edaboard.com/threads/252959/