[USRP-users] USRP2 FPGA development questions

Matt Ettus matt at ettus.com
Wed Nov 17 13:31:55 EST 2010


On 11/17/2010 10:05 AM, Marc Epard wrote:
> We're experimenting with changes to the USRP2's FPGA. We started with
> the UHD code and successfully built the same image downloadable from
> Ettus, but Xilinx ISE 12.2 reports thousands of warnings and some
> time constraint violations. This is only my second Verilog project
> (my background is in software development) and I have a few
> questions.
>
> How do you guys manage the warnings? Software development experience
> has conditioned me to treat warning as errors and eliminate each one.
> This doesn't appear to be possible with the Xilinx tools. The
> Filtering feature seems barely useful in that you can't cleanly
> isolate files or modules. Is there something I'm missing?

Unfortunately, it is essentially impossible to get rid of warnings in 
Xilinx tools.  The best you can hope for is to grep for the ones you 
care about.

> When do you take time constraint violations seriously? How do I know
> when my changes have caused a real timing problem?

Yes, very seriously.  You shouldn't see timing violations.  Which branch 
are you using, and how exactly are you doing the compile?

Matt




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