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DRA72x with Spread Spectrum Clocking

Prodigy 40 points

Replies: 5

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Hi:

I want to open Spread Spectrum Clocking on DRA72x, but I found that there are some notes about some related registers: Note: SSC feature is not supported.   

I try to confiugre PLL_SSC_CONFIGURATION1 and PLL_SSC_CONFIGURATION2 in my linux driver, and use oscilloscope to measure PCLK, found that the PCLK do change between f-Δf to f.

I want to comfirm whether DRA72x support SSC, if it support, how can I caculate the depth of SSC.

Best Regards.

Chao.

  • Hi,

    Your query was forwarded to experts.

    Regards,
    Mariya

     Be sure to read the Forum Guidelines and FAQ.

  • Hi Chao,
    TI doesn't support SSC feature for DRA72x. Registers are still there and SSC might(!) be working just fine, but it was decided to be unsupported. That's why is the Note in TRM.
    Regards,
    Stan
  • In reply to Stanislav Stilyanov:

    Hi Stan,
    Thanks for your reply.
    I config several values on the SSC register and get different depth of SSC. Is there any formula to calculate the depth of SSC.
    Besides, as you said TI doesn't support SSC feature for DRA72x. I want to know If I use this function, will it affect the stability of the system?
    Thanks & Regards,
    Chao
  • In reply to user5274607:

    Chao,

    Yes, SSC was not tested, therefore TI cannot guarantee it is functioning properly.

    If you wish, you can find SSC registers programming in early TRM versions: vA and vB, or in DRA7xx TRMs up to vM. It is not just one simple formulae, there is some more settings to take into account.

    Once again, keep in mind that TI is not responsible for SSC function and cannot give any warranties.

    Regards,

    Stan

  • In reply to Stanislav Stilyanov:

    OK, I know. Thanks, Stan. And Thanks, Mariya.

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