Frequency measurement using myRIO clock

[johndo76]

Hi everyone,

I am looking to find the frequency of an analog signal using a function generator connected to the MSP input of myRIO.

The idea is to use the FPGA target on the NI myRIO (40 MHz clock rate) as a reference clock of 10MHz, for example, to define the sample clock.

I added the myRIO while loop to the FPGA signal generator example: the voltage from the function generator is correctly acquired but building the waveform I can't measure the frequency, neither with the tone measurements VI or the FFT (figure 25). What is wrong?

How can I be sure that the two signals are synchronized (as well described here)? I guess with a timed loop and a master/slave architecture but I'm not sure how to implement it.

Thanks a lot 

John

[Skirpt]

Hi John,

What kind of error are you getting when you try to calculate the frequency of the input when you use the tone measurements VI or the FFT?

I would recommend checking out the following White Paper for instructions on how to synchronize your signals http://www.ni.com/white-paper/4217/en/#toc3. Let me know if this doesn’t work.

Cheers,