Use a switch by change not on/off status.

[Demon]

Interrupt on change is more efficient. But this is Koert's first post and he just joined, he hasn't given any indication to his level of PBP expertise..

Assuming he is a beginner, he's better off trying logic instead of interrupts to get the ball started, then switch to interrupts later as a challenge.

Koert, search for Darrel Taylor's Instant Interrupts in FAQ section. Unless you only do super simple programming, they help A LOT when using USB, timers, interrupts, and many more features.

Robert

[richard]

I agree with Robert contact bounce and such can really confuse an interrupt based solution ,unless you have some experience behind you. slow changing inputs can easily be read (and debounced) by using polling style solutions

[Archangel]

contact bounce can be marginalized with a short pause. IOC would trigger going to either logic state and his output would always start out at what it is initialized to. If he is not too worried about latency then even ON INTERRUPT would work, though I prefer Darrel's asm interrupts.