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Participant
Participant
3,038 Views
Registered: ‎06-27-2013

MMCM dynamic phase shift: psdone never asserted

I have been trying to simulate dynamic phase shifting in a 7-series MMCM module.  I assert psen for one clock cycle, then wait for over twelve cycles of the psclk, but psdone always stays low.  Also if I look down inside the MMCME2_ADV primitive, none of the ps signals look to be toggling or doing anything when I send psen. I made this module with the clock wizard, but the MMCME2_ADV seems to be configured correctly when I look at the source.

 

*I reset the MMCM at the beginning of my simulation.

*I am not trying to shift the phase until thousands of ns after the MMCM has locked.

*I remembered to enable the dynamic phase shift feature, and to enable fine phase shift on my output clocks, when I was configuring the clock wizard.

*The psclk is running, and psen is synchronous to it.

*I have tried both incrementing and decrementing; results are the same.

*The Vivado version used is 2017.1; the clock wizard IP version is 5.4

 

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Xilinx Employee
Xilinx Employee
2,984 Views
Registered: ‎04-16-2012

Re: MMCM dynamic phase shift: psdone never asserted

Hi @jhane

 

Are you observing this behavior in simulation?

If yes, share the simulation snapshot here.

 

What is the frequency of PSCLK? Is PSCLK clean? 

 

Thanks,

Vinay

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Participant
Participant
2,962 Views
Registered: ‎06-27-2013

Re: MMCM dynamic phase shift: psdone never asserted

Hi @vuppala

 

Here is a screenshot.  The top-level signals locked, psclk, psen, psincdec, and psdone are at the bottom.  Everything else is from inside the MMCM.

 

Yes psclk is clean.  It is running at 125 MHz.

 

mmcm.gif

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Visitor
Visitor
482 Views
Registered: ‎12-15-2014

Re: MMCM dynamic phase shift: psdone never asserted

It looks like this was never resolved.  Sadly I am seeing the same thing while simulating in Modelsim with models generated by Vivado 2019.1.

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Participant
Participant
395 Views
Registered: ‎09-11-2014

Re: MMCM dynamic phase shift: psdone never asserted

I had the same problem, using the MMCME2_ADV in VCS:  psdone never asserted.  I was using my firm's precompiled libraries.  (I instantiated the primitive myself; I didn't use the wizard.)  Then I tried recompiling the source (Vivado/data/verilog/src/unisims/MMCME2_ADV.v, version 2017.1, last revised 11/26/2014) into my work library and then it started working.  I don't understand why; I think the precompiled version I had been using was from the same source, but something must have been different.

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Moderator
Moderator
177 Views
Registered: ‎08-08-2017

Re: MMCM dynamic phase shift: psdone never asserted

Hi @kevinneilson @jhane @emcalnan @vuppala 

#1  make sure that you select USE fine PS in the clocking wizard IP

use_fine_ps.png

#2 When using the direct primitive instantiation, Make sure that you set the below attribute.

Capture.JPG

 

Capture.JPG

 

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