I have successfully connected an inex temperature board to my Arduino and it displays numbers like 460 at 24degC and 280 at 4degC. The documentation indicates that the resistance at 25degC will be 10K ohm. The range of the sensor is from -30degC to 150degC. I interpret this to mean that at the middle of the range, the output should be 512 (1024/2) yet 25degC is not in the middle of the range. Can someone tell me where I can find the formula to translate the output from the analog pin to deg C?
I did not see a direct conversion so I guess you will have to take readings at known temperatures and create a chart that converts values to temp and then write that into your code.
Aye, but there is the rub. The output is not linear and it's difficult for me to produce temperatures like -30degC and +100degC. I am in Canada and it will be a few months yet, I hope, before I see -30degC again.
Doesen't the board come with some documentation that explains the non linear response curve ? If not then i can't see any way around doing the calibration your self.
It would probably be simpler (and cheaper) to use the LM35 sensor http://www.national.com/mpf/LM/LM35.html it's pre calibrated to give you 10mV pr. degree centigrade, in a linear fashion over it's entire temperature range.
Thank you, MikMo. That's exactly the kind of advice a newby like me needs and I will certainly follow up on it.