Internet of Things with Python

Wiring an analog input pin with a voltage source

The easiest way to understand how to read the values from analog pins and map these values back to voltage values is to work with a very simple example. We will connect a power source to one of the analog input pins, specifically a pack with two AA or AAA 1.25 V rechargeable batteries in series. It is also possible to use AA or AAA 1.5 V standard batteries in series. Note that the maximum voltage with the two rechargeable batteries in series will be 2.5 V (1.25 V * 2), while the maximum voltage with the two standard batteries in series will be 3 V (1.5 V * 2).

We will use the analog pin labeled A0 to connect to the positive side (+) of the battery pack. Don't forget that the positive side (+) of ...