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Adventurer
Adventurer
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Registered: ‎08-01-2017

VIO & ILA become inactive when resetting in GTH example design

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Hi,

in KCU105 boad, I have run example design of GTH. I added some logics and modules to the example design.

Now my problem is when I give a reset signal through the VIO core, all my VIOs and ILAs become inactive. (All input/outputs become 0 and i can't see or drive any signal). It is more like that the clock is not arriving there.

 

After exploring and debugging my design I found the problem is from diagaram below.

Annotation 2019-10-13 115502.jpg

Clock input(Clk_in1) to MMCM is rx_usrclk2 the recovered clock from GTH. Output is 1/4 of that and RST signal is connected to the AND of two signals from two different VIO. These two VIOs are in freerun clk domain. 

When I assert any of the two signal mentioned, all my VIOs and ILAs become inactive (VIO/ILA from freerun clk, VIO/ILA from rxusrclk2 clk, VIO/ILA from 1/4 clk) it is like a board-dead situation!

The error after the event and running ILA is shown below:

Annotation 2019-10-13 1155022.jpg

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Explorer
Explorer
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Registered: ‎03-16-2019

Re: VIO & ILA become inactive when resetting in GTH example design

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check the debug core input clock.

Is that run with the output of this MMCM?

View solution in original post

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Teacher
Teacher
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Registered: ‎07-09-2009

Re: VIO & ILA become inactive when resetting in GTH example design

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the ILA needs a permanent clock,

do you need to reset the MMCM under user control ?


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Adventurer
Adventurer
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Registered: ‎08-01-2017

Re: VIO & ILA become inactive when resetting in GTH example design

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The clock is on-board 125 MHz clock.

Actually no, I don't need to reset the MMCM. But it must be possible, isn't it?

For example if the recovered clock got lost, how could we reset the MMCM to lock to its input?

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Teacher
Teacher
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Registered: ‎07-09-2009

Re: VIO & ILA become inactive when resetting in GTH example design

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You can reset a MMCM yes,
but that clock can not then be used in an ILA which needs a constant clock.

BTW: does the MMCM need resetting after its input is lost ?


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Adventurer
Adventurer
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Registered: ‎08-01-2017

Re: VIO & ILA become inactive when resetting in GTH example design

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What if after completely clean reset, that clock be available for ILA? Wouldn't it run?

I don't know. Does it lock to its corrected input after some input missing period without a reset?  

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Adventurer
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Registered: ‎08-01-2017

Re: VIO & ILA become inactive when resetting in GTH example design

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 Does it lock to its corrected input after some input missing period without a reset?  


According to the note below i found in PG065, No! It has to be reseted.

Annotation 2019-10-13 150737.jpg

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Teacher
Teacher
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Registered: ‎07-09-2009

Re: VIO & ILA become inactive when resetting in GTH example design

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resets are interesting,,
I'd normaly use the locked output of the MMCM to reset the fpga, but only the parts that need to be,

you might be interested in this

https://www.xilinx.com/support/documentation/white_papers/wp272.pdf
its very easy to over reset a design, and add massive amounts to your logic / implementation time,

Is your clock liable to be lost once board is powered up ?

Questions I'd ask are ,what are you trying to protect against, what do you want to happen when that situation happens, how can you design to meet that.

Sorry , regarding the ILA, it needs a clock, if you go stopping the clock, then the ILA is going to fail,

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Explorer
Explorer
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Registered: ‎03-16-2019

Re: VIO & ILA become inactive when resetting in GTH example design

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check the debug core input clock.

Is that run with the output of this MMCM?

View solution in original post

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Adventurer
Adventurer
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Registered: ‎08-01-2017

Re: VIO & ILA become inactive when resetting in GTH example design

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Thanks

Is your clock liable to be lost once board is powered up ?

Yes, it is the recovered clock of the GTH.

Questions I'd ask are ,what are you trying to protect against, what do you want to happen when that situation happens, how can you design to meet that.

I want the pll reset for the time I lost my recovered clock and gain it back again.

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Adventurer
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Registered: ‎08-01-2017

Re: VIO & ILA become inactive when resetting in GTH example design

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Hi @behnam_2705new ,

Yes, apparently it is connected to the output of the MMCM.

Now I'll try to solve the debug_hub problem and see what will happen.

 

In answer to @drjohnsmith , I had a design that the VIO/ILA clocks was not exactly freerun. When I gave proper clock to them, they would work and whenever I masked the clock I would face with the error mentioned.

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Teacher
Teacher
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Registered: ‎07-09-2009

Re: VIO & ILA become inactive when resetting in GTH example design

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taking step back,

   seems your using the recovered GTx clock as your main clock in your desing ?

 

Its normal to have a local clock, that runs constantly as your main lcock. The output of the GTx, comes in via a fifo, and the data is packets with the valid of the AXI bus.

The recovered clock is only then local to the GTx IP block,

If you could move over to this, then your problems of ILA / VIO and gated clocks would be solved.

 

 

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Adventurer
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Registered: ‎08-01-2017

Re: VIO & ILA become inactive when resetting in GTH example design

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Yes.

Your suggested design is good for some application. But in my application all my data is a stream data and I want the data to be processed every clock.

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Teacher
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Registered: ‎07-09-2009

Re: VIO & ILA become inactive when resetting in GTH example design

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The above technique of crossing from an intermitant clock to a continous clock is used in many many streaming applications, such as professional video.

If you are fighting the norm, then you can expect a more difficult route,

 

You now have an explanation as to why your desing stops working, and an explanation as to how other profesional systems work.

I think that about closes this case does it not .

 

 

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Adventurer
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Registered: ‎08-01-2017

Re: VIO & ILA become inactive when resetting in GTH example design

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The problem was the dbg_hub clock that was clocked by output of the MMCM. So whenever I reset the MMCM the dbg_hub will loose its clock.


I read the posts about "connect_debug_port dbg_hub/clk" but I still can't move the dbg_hub clock to the freerun clock it is stuck to the MMCM output. (IDK maybe because most of my debug cores are in that clock region)

So I deleted that OR of resets, now I can run my application with my logic reset, But still can't reset the MMCM! So I guess I must close this issue and persue the problem in debug forum.

 

Thanks for your helps