Debouncing

The v1 hardware version uses simple debouncing with 1 capacitor and 1 resistor. I learned all I know about debouncing from here.

I decided to debounce everything in hardware to make interrupt handling easier and more robust.

The design jazda is using:

               +  Vcc             +
               +  |               +
               +  [] R1 (pull-up) +
    |----|-----+--|               +
    |    |     +  |               +
SW \     = C1  +  | PINX          +
    |    |     +                  +
    |----|     +      AtMega      +
    |          +                  +
   GND         +                  +

It provieds instant reaction to closing of the switch and it comes back slowly. C1 is usually 1μF, but it should be adjusted to the quality of your switch.