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Using a thermistor with the FRDM board

Question asked by Steven Cohen on Apr 11, 2013
Latest reply on Apr 13, 2013 by David E Seymour

Trying to accurately measure the temperature of a heat sink using the KL25 FRDM board with an attached daughter card.  The thermistor is a 10K series from Vishay and so I bias it to 3v and use a pull down resistor recommended by Vishay.  I need to measure within a few degrees of accuracy from 70deg C to 100deg C.  The problem is the ADC bounces all over the place.  I have tried averaging, throwing out an errant reading, etc.  but I still do not have a stable solution.  I capture 16 bits from the ADC then throw out the least 4 bits.  I even tried to look at just 8 bits of accuracy.  Is there something I am missing?

Also I only need to capture 32 steps along that range. 

 

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