Mike has written an article about using cheap thermistors as an alternative to I2C/1-wire temperature sensors:
This post discusses the evaluation of a thermistor-based technique for small embedded systems capable of achieving uncalibrated temperature accuracy to rival expensive digital sensors. An experimental comparison of various sensors over temperature is then introduced.
It’s a great tip about powering the thermistor from a GPIO pin. So obvious, but I never thought of it.
You do potentially need to leave the GPIO to settle, esp if you put a cap on it via a resistor to reduce noise but protect the pin from surge draw.
I’m doing it also (at Mike’s suggestion) with an ambient light detector that would otherwise draw 20uA.
Oh, and set the GPIO to hi-Z input, not low output, when done, if you have a cap there!
Rgds
Damon
there’s also a similar article about ntc termistor usage with a precalculated table http://flux242.blogspot.de/2012/06/avr-stick-as-temperature-logger.html
I’ve managed to get cheap thermistors calibrated to about to +/- 0.2C with 3.3v Arduinos.
https://edwardmallon.wordpress.com/2017/04/26/calibrating-oversampled-thermistors-with-an-arduino/
Instead of playing whack-a-mole with the various sources of error, I simply rolled them into some synthetic Steinheart-Hart constants, and I was able to get the therm’s output onto the reference line from a si7051. The cool thing about ti is that the thermistor, and the reference sensor cost less than a single high precision thermistor would have. Not sure if this approach would work beyond 40 degrees of range, but that’s good enough for my purposes.