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Observer ranjeeth.rk
Observer
520 Views
Registered: ‎04-29-2018

IBERT not working at 11.88 Ghz

Hi,

I tried to program the design of IBERT in KCU105 at 11.88Gbps but the Serial I/O Links shows 9.5 Gbps only.

I'm working with Vivado 2017.4,
IBERT Ultrascale GTH (v1.3) IP is used.
I have set the Line rate as 11.88Gbps and refclock as 148.5 Mhz .
GTH location is quad228 and REF_CLK selection is MGTREFCLK0 228.

Screenshots showing the settings of IBERT IP  and Serial I/O link is attached.

ibert_1.JPG
ibert_2.JPG
ibert_3.JPG
serial_io_link_ibert.JPG
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6 Replies
Moderator
Moderator
502 Views
Registered: ‎07-30-2007

Re: IBERT not working at 11.88 Ghz

It would also be important to measure what is defined as the system clock in the IBERT.  If you fib to Vivado on the system clock frequency (that it uses to calculate the output line rate) this would be one way to get this result.  (100/125)*11.88=9.5

 

Partly for this reason I tend to always set the system clock to "internal" and use the reference clock as the system clock as well.  That way there is no additional set up needed for the system clock and the frequency is guaranteed.

Roy


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Observer ranjeeth.rk
Observer
459 Views
Registered: ‎04-29-2018

Re: IBERT not working at 11.88 Ghz

Hi Roy,

 

Thanks for the suggestion.

When i replaced 125 MHz with 100 Mhz clock, I am getting 11.88Ghz.

 

But I didn't able to understand the formula used by you.

Can you please explain what is 100 (numerator) in that formula ?

 

Ranjeeth

 

 

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Xilinx Employee
Xilinx Employee
442 Views
Registered: ‎08-07-2007

Re: IBERT not working at 11.88 Ghz

hi @ranjeeth.rk

 

what if you select Quad xxx clock as System Clock Source, instead of an External clock?

 

Thanks,

Boris

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Observer ranjeeth.rk
Observer
435 Views
Registered: ‎04-29-2018

Re: IBERT not working at 11.88 Ghz

 

Hi Boris,

 

I have selected Quad xxx clock as System Clock Source, and  when I supplied  100 Mhz to clk port of the Ibert instantiation., I am getting 11.88 Mhz.

I tried that just to check the formula mentioned by @roym.

 

But still I didn't understand the fomula. I didn't understand how @roym got 100 in the numerator.

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Moderator
Moderator
423 Views
Registered: ‎07-30-2007

Re: IBERT not working at 11.88 Ghz

I was only pointing out that the error proportion was the same as using a 100 Mhz  system clock when the system was using 125 Mhz in the calculation.  These kind of mismatches are often the cause of this line rate mismatch.

Roy


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Xilinx Employee
Xilinx Employee
411 Views
Registered: ‎08-07-2007

Re: IBERT not working at 11.88 Ghz

hi @ranjeeth.rk

 

from the screen shot, I see External is selected for System Clock Source.

Did you try selecting Quad xxx instead? Still show wrong line rate?

 

Thanks,

Boris

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