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Altera_Forum's avatar
Altera_Forum
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16 years ago

PLL reconfiguration (stratix III)

Hello,

I would like to make use of the S3's PLL reconfiguration feature.

Ideally, this would entail a host CPU programming the settings for the scan chain in order to target some (reasonable) frequency.

It looks to me like there's quite a complex bit of software needed to work out the appropriate multiplier/divider/counter settings. Does such bit of code exist that's not buried away within the Quartus software/megawizard.

Cheers,

Andy

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Is there a set of frequencies that you are planning on configuring the PLL to or is it essentially random? What I have done in the past is simply use the megawizard to get all the counter settings for each frequency configuration I was going to use, and record them.

    Jake
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I would prefer to generate the configuration based on similar parameters to those taken by the megawizard, however, the approach of using the output of the megawizard is reasonable.

    It seems to me it would make sense for there to be some (C-)code users could integrate with their control app to make this possible, as the code must surely already exist.

    Cheers,

    Andy
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I understand. I actually tried to create such a thing at one point but ultimately determined it wasn't worth the time investment. In addition, some of the Altera megafunctions are actually java applications which I've been able to decompile and retrieve the algorithms that way. However, with the PLL, this is not the case. If you happen to come across some useful code, or happen to derive it, let us know.

    Jake