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sidd's avatar
sidd
Icon for New Contributor rankNew Contributor
4 years ago
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Difference between logic elements mentioned in flow summary and synthesis summary

After compiling RTL, we get compilation report. In compilation report we get Flow summary, Analysis and synthesis summary. Both reports are giving me different number of logic elements used. What is the difference between two? LEs used has to be a same number in both reports right?

I have compiled for MAXV device.

MAX V CPLD programming specifications

  • sstrell's avatar
    sstrell
    4 years ago

    The final numbers to use are in the Fitter section of the compilation report. Any numbers from an earlier stage of compilation are estimates and usage before final Fitter optimizations.

3 Replies

  • sstrell's avatar
    sstrell
    Icon for Super Contributor rankSuper Contributor
    4 years ago

    The final numbers to use are in the Fitter section of the compilation report. Any numbers from an earlier stage of compilation are estimates and usage before final Fitter optimizations.

  • sidd's avatar
    sidd
    Icon for New Contributor rankNew Contributor
    4 years ago

    Thanks @sstrell for reply.

    I have one more question.

    What percentage of LEs ideally shall be used ? Any impact on performance if more than 90% of LEs are used?

    • sstrell's avatar
      sstrell
      Icon for Super Contributor rankSuper Contributor
      4 years ago

      It depends on the design. There's no ideal percentage. It may not be so much the performance as it is the Fitter's ability to fit a large design in the device while still meeting the timing requirements.