You should get responses that correspond to the resistance of the thermistor as measured
with a multimeter
Better Readings
When doing analog readings, especially with a 'noisy' board like the arduino, we suggest two
tricks to improve results. One is to use the 3.3V voltage pin as an analog reference and the
other is to take a bunch of readings in a row and average them.
The first trick relies on the fact that the 5V power supply that comes straight from your
computer's USB does a lot of stuff on the Arduino, and is almost always much noisier than the
3.3V line (which goes through a secondary filter/regulator stage!) It's easy to use, simply
connect 3.3V to AREF and use that as the VCC voltage. Because our calcuations don't include
the VCC voltage, you don't have to change your equation. You do have to set the analog
reference but that's a single line of code
Taking multiple readings to average out the result helps get slightly better results as well, since
you may have noise or fluctuations, we suggest about 5 samples.
Rewire as shown:
This sketch takes those two improvements and integrates them into the demo, you will have
better, more precise readings.
Serial.print("Analog reading ");
Serial.println(reading);
// convert the value to resistance
reading = (1023 / reading) - 1;
reading = SERIESRESISTOR / reading;
Serial.print("Thermistor resistance ");
Serial.println(reading);
delay(1000);
}
// which analog pin to connect
#define THERMISTORPIN A0
// how many samples to take and average, more takes longer
