working on a project to count length of thread

[akshay985]

i need to program a 89s52 to measure the length of thread , the thread moves over a circular goddet over which a proximity sensor is installed on the backside, when goddet rotates sensor senses and the 89s52 counts pulses.
i am trying to use a RTC1307 for a specific time like(5seconds) and clculate pulses and multiply t with goddet perimeter. so i get the length.

 

[BradtheRad]

I think I would simply keep a total count of pulses.

No need to count seconds, and then pulses per second, and then multiply. It becomes very awkward to do that.