You will need the Arduino Board, a 560Ω resistor, and LED and the code example below. We set the pinButton variable as integer 8 and we connect the button at pin 8 on the Board. Then the LED is ...

Wyatt]’s CPUVolt library provides a fast way to measure voltage using no external components, and no I/O pin. It only applies to certain microcontrollers, but he provides example Arduino code ...