Forum Discussion
ContributorMaking Nodes visible to SignalTap
I tried (* preserve_for_debug *) in VgaDisplay.sv but that still won't show vic_screen_lines in STP. I tried "Design Filter (all names)" as well - it still doesn't appear when I click List.
It is not listed in the 2 optimization result reports for removal, I can't find it in the compilation output, and I certainly can't see it in the RTL Viewer so it must have been removed somehow.
BUT.. I have just this minute tried searching for *vic_screen_lines* - and it appears! So I will have to remind myself to always use the asterisks either side of the node. I feel so stupid now - thank you for joining on me on this journey.
Always surround with asterisks, Sparky! Always!
Super ContributorIf you're using the pre-synthesis Signal Tap filter, make sure you've run at least Analysis & Elaboration again after making any code changes.
Also, with this filter, you shouldn't have to worry about nodes getting optimized away. That's usually only an issue if you are trying to tap post-fit nodes because you want them to be preserved through the compilation process.
Also, it's strange that you say you can tap top-level outputs because normally you specifically can't do that because there's no path back into the device from an I/O element. You would want to tap the register that was feeding the output instead of the output itself.
Another thing to try is to use virtual pin assignments in the Assignment Editor. That connects a signal node to stub logic to avoid getting optimized away during compilation even if the signal is not meant to ever connect to a top-level I/O.
SparkyNZYes I normally just do the "Start Analysis and Elaboration" when adding new nodes, to get SignalTap to have visibility of them. Right now I'm compiling the whole thing, shutting down SignalTap and restarting SignalTap but it still won't show those nodes with the Pre-Synthesis filter.
I think the Virtual pin assignment would take longer to do as well - these days I edit my Verilog with Notepad++ so I have access to keyboard macros and the likes to speed up editing.
