Hi everyone,

after try to find out how to measure the values of the thermistor 503 (that usually comes with the Arduino Starter Kit) I got it and I'm going to explain it to help others in my situation.

The 503 is a 50K@25C, so you need a R of 50 K to GND.

And the figures you need in order to "understand" the values sent by the thermistor:

float var2=1024-analogRead(0);

Resistance=(54*var2)/(1024-var2);

float Ln_Resist =log(Resistance);

Temp = log(Resistance);

float Ln_Resist3=Ln_Resist*Ln_Resist*Ln_Resist;

Temp = (1/(0.00237531+0.00024632*Ln_Resist+0.00000028*Ln_Resist3)-273);

return Temp; // Devolver temperatura