How to make friends with arduino with pt100 temperature sensor (platinum resistance thermometer)?

Question

Arduino

I came across this video where students based on pt100 and arduino make a thermometer with a screen. I realized that this is possible, but did not understand how?
In more detail, I want to get readable values ​​​​in degrees Celsius from three wired pt100 (-40 / + 500 C *), while only numbers like 730-735 are obtained and it is not very clear how and what to do with them.

Answer 1

If you mean a platinum thermistor, then by itself it does not give any readable values, especially temperature. However, its resistance corresponds quite closely to the temperature (at 0°C - 100 ohms, at 20°C - 107.79 ohms, etc.)
Thus, this resistance must first be measured. But the controller does not know how to measure resistance - only voltage. This means that you need to measure the drop in the reference voltage applied to the resistor and convert it into resistance according to Ohm's law.
Then the resulting resistance must be converted into temperature (according to the documentation of a particular sensor). Now it will already be readable and you can drive it to the screen :)

Answer 2

Not a big addition to the previous answer. Look for a description of the measuring bridges there with examples, everything is described in detail how measurements are made.