Time window

[Franko]

Hi,
I've been programming Pics for a while now and mostly done somewhat basic
routines(although very useful to me). Anyway,I have been trying to write code to do the following...

Upon a pulse to a pin,activate a timer within the Pic (16F84A) that would allow another input to a different pin to activate the main code.

So, After the first input pulse you would have say 20 sec to press the button that would activate the code. After the 20 sec has timed out, pressing the button would do nothing until another input pulse starts the timer again.

I've tried variations of count,pulsein,for/next,searching here and can't get it.

Can someone please just point me in the right direction ?

Thanks,
Franko