Formular for PT1000 to Celcius

Hey guys,
I had a Problem with an small Case and an PT1000.

So I created an Formular to modify the Value, given by the Arduino.

-> ((ave1*1.9378662109375)-1000)/(3.9074398)

This is a Formular for the direct Input of the PT1000... parallel to an 1k Ohm resistor

It works with an tolerance of 1,78 Degree Celcius

circuit:

Convert PT1000 resistance values to temperature

A PT1000 measured directly with Arduino's 10-bit A/D has a poor resolution of one A/D value per degree C at best.
Complicated formulas are not going to fix that.
A PT1000 is usually used with an external breakout board.
If you want to measure 'human' temps, it might be better to use a DS18B20.
Leo..