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Altera_Forum
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13 years ago

Materials regarding fitting algorithms used .

Hi all,

I need materials for place and route algorithms used in FPGA's today .

If anybody knows about link or can post some pdf , will be very helpfull.

I have gone through notes by RYAN SCOVILLE on altera wiki and found them quite interesting. Just want to know more .

Actually my main motive is to understand place and route and the variations with timing models and with sdc contraints although i have rough knowledge but just want to have a concrete one so that while giving settings and constraints i can predict what the tool will do to my design.

Any help will be appreciated .

Thanks

ASHISH

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    13 years ago

    I would also like to know as to where i can find details of Altera's timing models for ARRIA v.

    Thanks

    ASHISH
  • Altera_Forum's avatar
    Altera_Forum
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    13 years ago

    Can you elaborate on what you are looking for as far as place-and-route.

    For timing models, there is no spreadsheet or anything like that which gives all the values. Take a look at:

    http://www.altera.com/literature/wp/wp-01139-timing-model.pdf

    (My TimeQuest User Guide has a section on timing models too)

    It's really complex though. As mentioned, there is basically a mini spice-like simulator calculating values based on all sorts of parameters, so it's not like an element has a single delay value(for example, the same length routing wires can have different delays). Delays through a LUT vary by quite a bit depending on the input. Then there's on-die variation and rise/fall variation. It's just a lot of stuff going on, and can't be incorporated in a datasheet or something like that. Fitting a real design and looking at the timing is by far the best way(it gives you exact stuff to look at that is relevant to your design, while leaving out stuff that isn't). There's also many other layers. Synthesis, place and route and the many things they encompass all have such an affect on timing, it's really hard to separate one from the other. I've done analysis on designs that run faster/slower in different architectures in unexpected ways, and there's almost never a single smoking gun that explains it.
  • Altera_Forum's avatar
    Altera_Forum
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    13 years ago

    Oh great RYSC I also have gone through the TimeQuest User Guide and learnt a lot.

    Actually I have being giving my 24*7 to altera's quartus II since past 6 months.

    Have got some command over timequest (with your help) but want to get command over the approach specially want some insight on how the timing models beacuse i want to develop myself in synthesis as much as possible.

    Yes i will be waiting for some of your notes in timing optimization and something more in fitting too.

    Thanks for your help.