NI myRIO measurement of frequency of a digital signal - with Video.

[tomnz]

This simple program uses the FPGA on a myRio to detect the edges of a square-wave and sets a times to measure the period (number of samples between the positive going edges of the waveform). It is accurate from a few Hz up to 80kHz. A video goes with this.

https://www.youtube.com/watch?v=Fz4GIb455YY&feature=youtu.be

Top is the FPGA code and below is the host code that runs on the real-time processor.

[amit_IITP]

Hello. I have tried this code and also watched your youtube video. I am trying to get the spped from my quadrature encoder. I have converted the frequency code to velocity measurement code as seen in your video. I am getting the reading but it is fluctuating very rapidly in y axis. My motor is running at 1000 rpm and I am getting other rpms along with 1000 rpm in waveform window.  The video of speed measurement is below.

Please help me.

Thankyou

[amit_IITP]

Hello. I have tried this code and also watched your youtube video. I am trying to get the spped from my quadrature encoder. I have converted the frequency code to velocity measurement code as seen in your video. I am getting the reading but it is fluctuating very rapidly in y axis. My motor is running at 1000 rpm and I am getting other rpms along with 1000 rpm in waveform window.  The video of speed measurement is below.

Thankyou

[tomnz]

You could try increasing the sampling frequency. That is probably the problem.

[amit_IITP]

Thank you Tomnz. I will try it.