How can I get the acurate freqency value iputted in PFI0?

[Bird]

Geneva L.

I am sure that the input freqencey doesn't have noise because I use freqency generater to generate it and I also use oscilloscope to check for it. But I still get the wrong frequency value.

I had tried the measurement of "Pulse width, high" method to check the frequency, and I can get the exact value of it, while it still returns some error valves (1/20). But I set the gate = "PFI0" & source = "Internal CLK", I am very confused about gate and source value. Because I can't get any pulse width value if I set source = "PFI 0" & gate ="defaule".

Do you have any other suggestion?

Bird

[Filipe A.]

Hello;

Try to run the same example, but instead of set the PFI0 to be the gate, hardwire the pulse train directly to Counter Gate pin, and select the period rising Edge measurement. As the internal timebase is set to 100000, the number you get must be multiplied by the timebase for you to have the period measurement.
If you set the source to be PFI0 and gate to be default, you won't get any value because the source pin must be the timebase frequency, which will be used as reference for the gate pulse train.
Hope this helps.
Filipe