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Altera_Forum's avatar
Altera_Forum
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14 years ago

how to choose clock frequency for nios components

Dear All,

I'm here to ask for a fundamental. When I add a component in a NIOS system often have doubts about the right clock to connect to. I mean, there are some modules that provide outputs to drive external device(jtag uart, lcd, epcs devices....etc). Devices requires correct timing at least in terms of maximum switching speed.

I understand that is not realistic to have always all the components in the system clocked with the same clock, so for example clock crossing bridges are povided. But I wuold like to know wich is the correct clock frequency for modules. I mean, where to find the informations about clock selection for jtag uart or epcs controller?

Thanks a lot in advance.

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    Hi,

    It depends on the components to use.

    It's always simpler to have all of them on the same clock, unless you're obliged to do otherwise:

    - need pll clock compensation for different parts of a big design.

    - have camera or VGA or other that already have a different clock.

    - need different performance and power savings strategies on different components

    that's as far as I know, and I guess the list can be completed...
  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    thank WASS,

    I was actually asking information on how to find informations about NIOS components clock requirments.
  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    :) but not the clock details...

    let's do the case of the Optrex16207 LCD controller core. I don't see any reference to the component clock selection.