Obviously costly with timers/interrupts and multiple inputs, but power’s power. Report comment. ... I also cover a workaround for the limitation of 2 interrupts on Arduino. Report comment. Reply.

This Arduino-based Pomodoro timer project also uses this 25-minute cycle. Once you push the button to start the timer, it will run for 25 minutes, display a count-up timer and a "Study time ...

Raspberry Pi programmable timer “To make things more interesting, you can modify the provided source code, and re-program the Ninja Counter itself using an external Arduino Uno!