Forum Discussion
New ContributorThe question about arria10-netlength
hello,
I downloaded this table(10AS032EF29_netlength.xlsx) from the official website, but there are two columns in it: Total Length (mm) and Total Delay (ps). Which data should I take as the criterion? What value should I set in the PIN DELAY of the PCB?
11 Replies
Farabi_AlteraRegular Contributor
Hello,
You may use Total delay(ps) as your pin delay setting.
regards,
Farabi
gongmhHello, Farabi
Thank you very much for your answer.
I still have questions:
why is the the ratio of "total length(mm) "and "Total delay(ps) " different？It's supposed to be a fixed ratio。
or what is the difference of the "total length(mm) "and "Total delay(ps) "?
Best Wishes.
- gongmh
Hello,
Can anyone answer that? thanks a lot.
best wishes.
AqidAyman_AlteraHello,
May I know why you think it supposed to be a fix ratio?
Regards,
Aqid
- gongmh
Hello，
first, I think the ratio of length to time represents the rate, it's a constant value.
second,The purpose of equilength is isochronous. The length should equal the length of the delay.（1mm=39.72mil ， in FR4 PCB, 1ps≈6mil ）
If they're not equal, it's a proportional relationship. I don't know if I understand this right?
Regards,
gongmh
- AqidAyman_Altera
Hi,
Okay, thank you for feedback.
I am consulting the internal team to get the confirmation on this matter. I will come back to you with the answer as soon as possible.
Thank you for your understanding.
Regards,
Aqid
- AqidAyman_Altera
Hi,
Can you share the whole part number of the Arria 10 device that you used?
- AqidAyman_Altera
Hello,
I got some input from the internal team on this question.
This design has been routed in strip line and microstrip line routing. These two have a difference speed between them. The speed in the microstrip line is faster compared to the strip line. Thats why the ratio is not fix.
Regards,
Aqid
- gongmh
hello ,
Do you mean that there are microstrip lines and strip lines inside the FPGA? So the two values are different?
My understanding is that the delay should be the same in FPGA inside, Because the routing is already established.
best wishes,
gongmh
- AqidAyman_Altera
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- gongmh
hello,
thanks for you help.Is there anyone who can answer my question?
