FPGA and External Clock Source

[kevin.key]

Using a PXI-7854R, is it possible to run a process on an external clock source? As far as I can tell, you could potentially by routing the external clock to one of the RTSI trigger lines. Is that correct? Is it possible to route through one of the connectors on the PXI-7854R? If not, I also have a PXI-6229. Can the external clock be routed to the RTSI line through the PXI-6229 and then to the PXI-7854R to execute the process?

[kevin.key]

Actually, it looks like you can't use the RTSI signals as a clock source. As far as I can tell you can only really use the 40MHz onboard clock and to sample the external clock, and the external clock just has to be slow enough to not miss any edges.

[alcava.cr · Accepted solution]

Hi there,

Unfortunately no, as mentioned here and here. The best workaround, is to just gate the external clock with DIO on a case structure. Although, that's not going to have any kind of phase sync and you may miss clock cycles depending on how long and how fast your external clock is running (not really an option). I hope this answers your question.

[kevin.key]

Haha, oops. Thanks for the reply. I had a feeling I posted the question before, but couldn't find it.

[alcava.cr]

no problem