10-26-2018 04:52 AM
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.
10-26-2018 07:33 AM - edited 10-26-2018 07:40 AM
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.
10-29-2018 10:39 PM
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 ?
10-31-2018 01:32 AM
what if you select Quad xxx clock as System Clock Source, instead of an External clock?
10-31-2018 03:16 AM
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.
10-31-2018 07:42 AM - edited 10-31-2018 07:44 AM
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.
11-01-2018 01:54 AM
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?