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Altera_Forum
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21 years ago

Nios-I speed in QuartusII 5.0

Hi,

I've just moved from Quartus 4.0 to Quartus 5.0, re-generated my Nios sub-system using SoPC Builder, and the run the Cyclone-based design through Quartus syhthesis and place & route.

The speed of my design has dropped from almost 90Mhz before the move to 72Mhz now.

Has anyone seen a similar speed decrease associated with the later version of the tools?

Alan

6 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    21 years ago

    I could have sworn I saw this posted somewhere else.

    Check your Quartus project settings to make sure nothing was modified in the upgrade (a lot has changed since 4.0). I have noticed "Auto Fit" being turned on sometimes after the upgrade and you want that to be set to "Standard" in most cases.

    Here's a set I find useful for big designs like the standard and full-featured reference designs:

    Multiplexer restructuring --> off

    State machine encoding --> one hot (make sure you don't have any large statemachines in your design since they will become very big)

    Standard fitter effort

    Combinational physical synthesis

    Normal physcial synthesis effort

    Hope that helps
  • Altera_Forum's avatar
    Altera_Forum
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    21 years ago

    Hi,

    Yes, I posted this query on comp.arch.fpga also.

    Thanks for the suggestions but it's not a QuartusII-4.2/5.0 synthesis/fitting issue as such,

    it's something to do with the SoPC-Builder in 4.2 and/or 5.0.

    I don't have any problem importing the 4.0 database into 4.2 or 5.0 and running it

    through synthesis and fitting, when I do that the timing meets the 90Mhz target.

    However, if I re-generate the Nios sub-system using SoPC-Builder in 4.2 or 5.0

    and run through synthesis/fitting, then the performance drops to around 70Mhz.

    If I was a cynic I would wonder whether Altera have made Nios-I slower in order to push

    people towards Nios-II :-)

    Alan
  • Altera_Forum's avatar
    Altera_Forum
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    21 years ago

    I know you are only kidding, but let me just state that we haven't slowed down Nios-I. Our Nios-I activities mainly consist of regression testing

    to ensure Nios-I still works on new versions of SOPC Builder and Quartus.
  • Altera_Forum's avatar
    Altera_Forum
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    21 years ago

    I've had the same problem

    And i find solution using design compiler

    it try to implemend design several times and afters this design compiler save in project parameters for best fit.

    So - use design compiler in Q5 - it works
  • Altera_Forum's avatar
    Altera_Forum
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    21 years ago

    Hi James, yes, i was only joking about Altera purposely slowing down the Nios-I, just to be clear about that!

    Thanks Alex for that suggestion, I'll try that to see if it works for me also.

    Alan