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Altera_Forum's avatar
Altera_Forum
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20 years ago

How to use PLL?

Hi:

We all konw that Altera provides PLL,These PLLs offer clock multiplication and division, phase shifting, and

programmable duty cycle and so on.But I don't know how set PLLs when I change the setting of PLLs in my program. For example,modify clock multiplication and division in my program.

Thanks

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    Hi,

    Due to the internal implementation of PLLs in Altera FPGA (at least for Cyclone) devices, duty cycle, phase shift, and so on, are not software programmable. You only have the ability to modify them at design time. Take a look at the Cyclone device manuals, they have included very usefull information about this subject.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    PLL's are a device-specific thing and on some devices, they do support "reconfiguration" on the fly. Cyclone doesn't happen to be one of those devices, but I believe that both Cyclone II and Stratix II do support this feature.

    - slacker