Hi Waqar,

Perhaps what you should do is first figure out the algorithm you need to detect the pulses. You've already been given suggestions for those.

Ignoring those (as you seem often seem to) what would YOU do to detect a pulse coming your way, at a VERY slow rate compared to normal speed of thought. Like you were reading a blinker (heliograph) message being sent very very slowly. The light goes on, and you know that, OK, here comes a pulse. How long is it? How long after it goes away does the next pulse come? Maybe another pulse DOESN'T come along. How many pulses have you seen? Think about it.

Once you get the idea of WHAT you need to do to detect pulses, then you can start working on HOW to implement it.

Design first, implement/code second.

Once you implement it, or what you think is that implementation, fire up your simulator and see if it works. Force an input pin high, give it some clocks, check timers and such...is it working??

If it isn't, THEN ask us what's wrong.

Dennis