Maximum Frequency

Discussion in 'VHDL' started by zlotawy, Oct 7, 2007.

  1. zlotawy

    zlotawy Guest

    Hello,
    I use Xilinx ISE. In Synthesis Report I got this message:

    "Maximum Frequency: 18.019MHz".


    What causes that frequency? What should I do If I would like more?


    Thanks,
    zlotawy
    zlotawy, Oct 7, 2007
    #1
    1. Advertising

  2. zlotawy

    KJ Guest

    "zlotawy" <_SPAM.pl> wrote in message
    news:febaol$367$...
    > Hello,
    > I use Xilinx ISE. In Synthesis Report I got this message:
    >
    > "Maximum Frequency: 18.019MHz".
    >
    >
    > What causes that frequency?

    ISE takes the VHDL code that you've written and comes up with a bitstream
    that will implement the logic that you've written once it has been
    downloaded into whatever device you've targeted. Inside that device there
    are logic cells and flip flops and whatever the device happens to have. ISE
    will also perform static timing analysis and calculate how fast the design
    can be run at and still meet whatever timing requirements you may (or may
    not) have specified). Generally speaking, 'maximum frequency' is talking
    about the how fast two flip flops that are internal to the device can be
    clocked at when implementing YOUR particular design. Other designs
    implementing some totally different function may operate faster (or slower).

    >What should I do If I would like more?
    >

    Unless you're targetting some very old family of parts, 18 MHz is very slow
    which likely means that the way you've written your code is probably not in
    synchronous fashion and would likely need a massive rewrite (~100 - 200 MHz
    is usually not hard to attain, but again it depends on the design and the
    designer).

    But as a general rule, you would use ISE to find what the slowest path are
    (i.e. the ones that are limiting your design to 18 MHz) and work on
    rewriting those areas to speed them up by getting rid of levels of logic and
    possibly pipelining the design somewhat.

    KJ
    KJ, Oct 7, 2007
    #2
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Skybuck Flying

    Maximum clock frequency ?

    Skybuck Flying, Aug 2, 2005, in forum: VHDL
    Replies:
    20
    Views:
    5,504
    Colonel Forbin
    Aug 10, 2005
  2. Skybuck Flying

    Re: Maximum clock frequency ?

    Skybuck Flying, Aug 2, 2005, in forum: VHDL
    Replies:
    0
    Views:
    556
    Skybuck Flying
    Aug 2, 2005
  3. x1
    Replies:
    9
    Views:
    316
    Rick DeNatale
    Oct 12, 2006
  4. PerlFAQ Server
    Replies:
    0
    Views:
    203
    PerlFAQ Server
    Feb 1, 2011
  5. PerlFAQ Server
    Replies:
    0
    Views:
    190
    PerlFAQ Server
    Mar 26, 2011
Loading...

Share This Page