Atmega328p, sensor and LED project

Projects General Guidance
1

Hello, I want to make a product that uses three PT 1000 sensors to measure the temperature of water, I have three different colored LED's that light up based on the temperature. My plan is to use two AAA batteries. How I measure the temperature: I put a resistor on each leg of the sensor and connect an analog input to one of the sensors legs. I send the supply voltage into an analog input aswell.

Since the voltage is not constant how can I measure precisely with varying voltage?

2

The default analog reference is Vcc, so there is no problem with varying voltage. All you care about is the ratio, the actual voltage is irrelevant.

Note that if you keep your LEDs on all the time, you're going to run out of battery really soon.

3

Thank you for your answer, that helps me a lot!

4

Use 3 ds18b20 sensors , they will work better/easier