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Observer mennsesc
Observer
934 Views
Registered: ‎03-02-2012

Vivado waveform behaves erratically

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I am new to Vivado, but have a lot of experience with ISE and chipscope.

 

My code compiles with no critical errors or timing issues and I have successfully added an ila debug port.  The part is programmed.

I am having trouble observing a waveform and the controls are behaving in a way that is very unlike chipscope.

If I set up a trigger with no conditions and select "run trigger" the core status continuously changes between pre-trigger, waiting for trigger and post-trigger, sometimes idle.  The window sample changes continuously with no discernible pattern.  But, even though signals are present in the Waveform window no waveform data is displayed.

Halting and selecting run trigger immediate results in the same behavior.

The behavior is the same whatever the state of the auto retrigger.

 

What I find even more mysterious is that earlier I had no trouble when I chose signals from another clock domain.  Then I removed all of the signals from the original clock domain and added signals, all from a different clock domain and the problems started.  Both clock domains are sourced from the same MCMM.  There is nothing fancy about these clocks.

 

I am using Vivado 2017.4 and the target is on a Trenz TE0725 development board.

 

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1 Solution

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Moderator
Moderator
1,288 Views
Registered: ‎10-19-2011

Re: Vivado waveform behaves erratically

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You can try a refresh on the device and to see if that kicks off the resync of the mmcm and the ILA core. However this is very typical behavior of a non-free running clock. If you are holding the MMCM in reset that would cause this type of behavior. I would recommend trying something besides the MMCM. Also make sure your core is in the same clock domain as your debug probes, otherwise you will run into other issues. Another issue that might cause this is timing, make sure your design is meeting timing.
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2 Replies
Moderator
Moderator
1,289 Views
Registered: ‎10-19-2011

Re: Vivado waveform behaves erratically

Jump to solution
You can try a refresh on the device and to see if that kicks off the resync of the mmcm and the ILA core. However this is very typical behavior of a non-free running clock. If you are holding the MMCM in reset that would cause this type of behavior. I would recommend trying something besides the MMCM. Also make sure your core is in the same clock domain as your debug probes, otherwise you will run into other issues. Another issue that might cause this is timing, make sure your design is meeting timing.
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Don’t forget to reply, kudo, and accept as solution.
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Observer mennsesc
Observer
861 Views
Registered: ‎03-02-2012

Re: Vivado waveform behaves erratically

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Free running clock was the problem.  I had inadvertently set a very high clock rate that the Artix couldn't maintain (mismatch between the MMCM input frequency and the actual input frequency).  It now works as expected.

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