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TMS320F28388D: External 25MHz crystal for USB Boot Mode.

Luke Chen
Expert 5090 points

Part Number: TMS320F28388D

Hi Champs,

My customer uses external 25MHz crystal for application, so he cannot use USB Boot since USB Boot ROM code needs 20MHz crystal for USB function.

But I think it is possible using SCI Boot to load flash kernel software to RAM, run the code and set AUXPLL to 60MHz from external 25MHz crystal for USB module, then use USB port for software upgrade, is it correct? Is there any concern with this USB upgrade method?

If this is workable, then customers still can use USB for software upgrade even they use 25MHz crystal for EtherCAT function.

Please advise your comments, thanks.

Regards,

Luke

  • +1
    TI__Guru** 117311 points

    Hi Luke,

     But I think it is possible using SCI Boot to load flash kernel software to RAM, run the code and set AUXPLL to 60MHz from external 25MHz crystal for USB module, then use USB port for software upgrade, is it correct? Is there any concern with this USB upgrade method?

    Yes, this is like secondary bootloader so it should be ok. Just to be clear in this case, customer will be loading full USB app along with PLL code and use that for loading the code and will not depend on USB BOOT code in ROM. Right ?

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    TI__Expert 5090 points

    Vivek,

    Yes, you are right. Thanks for your response.

    Regards,

    Luke