Use one of the internal timers, set it up to divide the clock by 16. Assuming you don't need them for anything else like PWM or Tone(). I'd use Timer1 or Timer2. Timer0 is needed for millis(), so that's the last one I'd mess with.
Use one of the internal timers, set it up to divide the clock by 16. Assuming you don't need them for anything else like PWM or Tone(). I'd use Timer1 or Timer2. Timer0 is needed for millis(), so that's the last one I'd mess with.