I am trying to start timer on the positive transition from external source like when I push the button, timer start counting.
The code I wrote works well with internal instruction clock but not from external source. I am really frustrated for not figure out whats wrong with this. Can someone please help me out. Please?
A typical push-button generates multiple transitions when you press it. This is known as 'switch bounce'
So either by circuitry (usually a R and C connected properly) or by means of clever software code, you have to 'de-bounce' your switch before it can be meaningfully used.