Use a switch by change not on/off status.

[Demon]

Off the top of my head in pseudo-code:

SwitchIn VAR PortB.0
OldState VAR BIT
SwitchState VAR BIT

OldState = SwitchIn
SwitchState = 0

Main:
  IF SwitchIn not = OldState THEN
    SwitchState = SwitchState ^ %1  ' Switch has been toggled
    OldState = SwitchIn
  ENF-IF
GOTO Main

Robert

[Archangel]

I would use interrupt on change. ISR just changes output port status. Set port status in start up code to " your safe off status" set interrupts off until pic is stable then enable interrupts. Whatever status toggle switch is in initally is irrelevant as changing it triggers the interrupt.

[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.