High frequency counter

[MikeBZH]

Hi,

I would like to measure the frequency of a square wave signal up to 20 MHz.

I do not want to pre-divide the frequency to avoid a loss of accuracy and/or increasing the measurement time.
I am currently using a PIC 18F2685. It works fine with the signal applied to Timer 3 but only up to 2 MHz.

Does somebody know a PIC 18F with a timer able to count at this high frequency ?



Many thanks

MikeBZH

[Ioannis]

Hi Mike.

Maybe this can help you:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiLg9n_rrHsAhXntYsKHTnTDkYQFjAAegQIBhAC&url=http%3A%2F%2Fww1.microchip.com%2Fdownloads%2Fe n%2Fappnotes%2F00592d.pdf&usg=AOvVaw0x4YFN7i9LYSNCf3dHlJrs

With a humble 16C5x pic can measure up to 50MHz.

Though use of prescaler is necessary, it does not reduce accuracy.

Ioannis