FPGA and External Clock Source

[Masoud_A]

Hello,

I am new to FPGA world and trying to use an external clock for NI PXIe-1073 that has a PXI-7851R IO. I tried to feed the clock signal using a digital input, but the digital input does not show up in the clock options of time loops in labview FPGA.

I would appreciate it if you could help me in this issue.

Thanks,

Masoud

[RandallCrandall'sCandleHandle]

Hey Masoud_A,

Take a look at this forum post for some more information on this:

https://forums.ni.com/t5/Real-Time-Measurement-and/Timed-Loops-with-External-Clocks/m-p/2209902/high...

The short answer is that this is not supported on our R Series cards. However, the workaround posted in that forum post should be a good start.

Cheers,

Ryan C.

[Masoud_A]

Hi Ryan,

Thank you for your answer. I checked that forum and I don't think using a SCTL to sample the external clock into a local variable will provide the accuracy that I am looking for. Is there any new IO that provides an external clock option?

Thanks,

Masoud

[RandallCrandall'sCandleHandle]

Hi Masoud_A,

What do you think about sampling and then using the case structure without a local variable?

The forum post is also up-to-date about the I/O. There aren't currently any R Series or Compact RIO devices that support the external loop timer.

Cheers,

Ryan