If the input pin has a pulldown on it (along with the pullup to 5v) you need to factor that in for either a NTC or PTC. The pulldown will skew the calibration significantly at higher resistance values, and have minimal effect at low resistance values. (R*pulldown value)/(R+pulldown value)= correct resistance value for temp. AKA Equivalent Resistance for parallel resistors. Not uncommon for a 100K pulldown to be on the input pin.
By using very low tolerance thermistors and using the mfg cal data you can build VERY accurate sensors compared to OEM +/- 10% units.
The correct way to calculate the resistance to voltage table for a thermistor that has both a pullup and a pulldown would be;
Vin=Pullup V *(Equivalent R/(Pullup R + Equivalent R))
Equivalent R = (R * Pulldown R)/(R+Pulldown R)
How MS Reads Temperature (Roger Enns)
Forum rules
Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.