Hi, I need to determined a square digital waveform's frequency. Any suggestions on how to do that?? I am thinking of using one of the i/o pins as input from and external source and determining that the frequency of the waveform on that input is 424hz. Please advice...

I had read some other threads about using the counter in the microcontroller, but I still don't quite understand the techniques used.
Please help.

Thank you.