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Scholar helmutforren
Scholar
2,057 Views
Registered: ‎06-23-2014

What does this timing warning mean, please?

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I'm using Vivado 2017.1 and I'm new at trying to get a project to meet timing.  I get the following summary of Inter-Clock setup issues:

 

Inter-Clock Setup Summary2 201708191030.jpg

 

I believe I understand Path 685, and I am currently addressing it.

 

I do not, however, understand the four with yellow arrows.  Those seem to be WARNINGS.  Below is detail for Path 688.  Hopefully it's large enough for you to read.  (If not, I think you can zoom your browser view.  Chrome uses control-mousewheel.)

 

Inter-Clock Setup Path 688 201708191030.jpg

 

So why does this have a yellow arrow, which I assume is a warning?  Note that "ROIC_stream_fifo" is a clock domain crossing FIFO.  The source and destination signals seem to be INSIDE this fifo.  Here's the instantiation:

 

    i_ROIC_stream_fifo_dout ROIC_stream_fifo_dout();    // Instance the interface
    
    FIFO_ROIC_stream_two_clk ROIC_stream_fifo (
        .rst(rst0),
        .wr_clk(ROIC_stream_fifo_din.din.ROIC_clkdiv7),
        .rd_clk(clk),
        .din(ROIC_stream_fifo_din.din.data),
        .wr_en(ROIC_stream_fifo_din.din.wr_en),
        .rd_en(ROIC_stream_fifo_dout.dout.rd_en),
        .dout(ROIC_stream_fifo_dout.dout.data),
        .full(ROIC_stream_fifo_din.din.full),
        .prog_full(ROIC_stream_fifo_din.din.prog_full),
        .empty(ROIC_stream_fifo_dout.dout.empty)
    );

and note that the data is 117 bits.  I see [0] through [1] in the original summary (first image above), so if that's data, it's not warning about all the bits.

 

Anyway, I would think everything should be fine when using this FIFO.  So is that yellow arrow actually a warning or not?  And if it is, why and how do I get rid of it, if at all?

 

Thanks very much,

Helmut

 

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Voyager
Voyager
3,769 Views
Registered: ‎06-24-2013

Re: What does this timing warning mean, please?

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Hey @helmutforren,

 

So is that yellow arrow actually a warning or not?

No, that yellow arrow is just a yellow arrow ...

See this other thread.

 

Best,

Herbert

-------------- Yes, I do this for fun!

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Voyager
Voyager
3,770 Views
Registered: ‎06-24-2013

Re: What does this timing warning mean, please?

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Hey @helmutforren,

 

So is that yellow arrow actually a warning or not?

No, that yellow arrow is just a yellow arrow ...

See this other thread.

 

Best,

Herbert

-------------- Yes, I do this for fun!

View solution in original post

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