timer on 16f877

[goodpickles]

My 16f877 is running at 4 mhz. I want to use it as a speedometer. I need some way of measuring the elasped time between pulses. I was thinking of useing timer1, but even with the prescaler it will time less than 5 seconds...,or are my calculation incorrect? What is a good way to accomplish this?

 

[Nigel Goodwin]

My 16f877 is running at 4 mhz. I want to use it as a speedometer. I need some way of measuring the elasped time between pulses. I was thinking of useing timer1, but even with the prescaler it will time less than 5 seconds...,or are my calculation incorrect? What is a good way to accomplish this?

A speedometer is basically a frequency counter - if you check the MicroChip application notes there's a very old one for a auto-ranging frequency counter.

Or you could check the EPE website, they did a project for a speedometer a number of years ago.