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effisio

Nexys Video HDMI Demo - Critical Warning about timing requirements not met

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Hello,

I downloaded the latest release of the "Nexys Video HDMI Demo" from Github  (Nexys-Video-HDMI-2016.4-2.zip) and I installed Vivado 2016.4 only for the purpose of implementing the hardware design and generating the bitstream of this demo. I generated the project by executing the tcl-script in the proj-folder and then generated the bitstream. The write_bitstream was completed successfully but for the implemented design Vivado reported one critical warning:
[Timing 38-282] The design failed to meet the timing requirements.
According to the Timing Report this warning refers to the Path from "hdmi_i/dvi2rgb_0/U0/TMDS_ClockingX/aLocked_reg/C" to "hdmi_i/rst_mig_7series_0_pxl/U0/EXT_LPF/lpf_int_reg/D"
with source clock mmcm_clkout1 and destination clock dvi2rgb_0_PixelClk. The reported slack is -0.787.
Any timing constraints of this should have been provided by Vivado automatically, so what could I do about this warning?
I tried this on three different machines, always getting the same critical warning.

Eff

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1 hour ago, effisio said:

Any timing constraints of this should have been provided by Vivado automatically

It's true that many ISE and Vivado IP provide some timing constraints but that doesn't mean that every design using the IP will have no failing paths. A lot of people are unaware that their designs have constraints that they didn't provide. I have worked on many designs where all constraints were met on one day and not the next with minimal or no source changes. I've worked on many projects where all constraints were met and the hardware might appear to be functioning *perfectly* but on the next bitstream exhibiting odd behaviors, still with a perfect timing score. As far as I know this is how things work for complex designs or some designs that utilize most of a parts resources. If you want  to have a secure job then be the one who can take all of the teams masterpieces and understand how to create final working bitstreams for the company's products day after day. Some companies don't even have a person with this level of competence.

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