Hi everyone! I'm currently working on a SparkFun Arduino Pro Mini ATMega 328 5V/16MHz connected to a PC which is powered by an external 14.8V battery. I would like to get the voltage level of my battery left from my Arduino board but isn't sure how to go about doing it. Is there a certain pin that I can retrieve this information from?
You have to be sure that the ground of the battery is also the ground of the PC and the Arduino.
To measure a voltage, you can use a voltage divider with resistors, although some current is going through those resistors.
To measure a voltage I would recommend the internal reference of 1.1V
Suppose you use analog pin A0 to measure the voltage.
A voltage divider could be 10k from A0 to GND and 220k from A0 to the battery.
That way you can measure 0 to 24V.