On Oct 19, 2009, at 8:29 PM, h4ctic wrote:

> So will it be like, choose pulse edge, enable
> interrupt on say rising edge and then turn ON LED? But how to turn  
> it OFF
> when square wave pulse is low?

After turning on the LED, reset the interrupt to be on the falling edge!
See also (maybe) "interrupt on change" interrupt available on some pins
of some PICs...

BillW

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