I need to count pulses from a fast clock source (50 Mhz +). Obviously that's beyond what a pic can do without help. My plan (at least until I find a better one) is to run the clock through an external counter of sufficent width to divide the clock to something the pic can handle. Then I can just shft a few bits, read the external counter and reconstruct the real count.

But I need to decide how much counter I need, and that's dictated by how fast I can clock timer 1 in async mode, so...

If I'm correctly interpreting the datasheet for the 16F87xA, the T1CLK input period in async counter mode is 60 ns for the 'F' part and 100 ns for the LF.
So that's 16.6 MHz and 10 MHz right?

If I used an LF part at 5v, would it still be limited to the lower spec?


I'd be interested to hear about anyone else's experiences using timer1 near it's maximum speed.

Unless there's a better option I'm overlooking?

Thanks
-Denny