How do AD9914 moninj probes work?

jfniedermeyer

Hello!

We are trying to debug some problems we are having with our AD9914 DACs in a NIST_QC2 backplane seated in a KC705. DDSs aren't initializing reliably. Even if they do, when changing frequency, the moninj DDS widget will show the desired new frequency but the DDS will not change its output.

We are trying to understand how the moninj AD9914 probe is functioning, but quickly get lost in gateware and Migen code. What we are most interested in is do the AD9914 moninj probes monitor the frequency tuning words being sent down the bus or do they read back the ftw from the DDSs?

Any other information on how to better understand moninj would be very useful as well!

Thanks all!

Edit: Apologies for not using the support tag. I thought I had clicked it instead of general and can't figure out how to change tags.

sb10q

They are monitoring the data sent. Reading back would obviously cause performance problems or interfere with real-time operation of kernels.
You probably want a hardware logic analyzer or oscilloscope to debug your current issue.