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C5504 pin multiplexing issues

John Fisher
Expert 1030 points

1. In the C5504 datasheet, sprs659f.pdf table 4-4, I think there should be a column for mode 0, with all dashes, just to make it crystal clear the multiplexed pins mentioned in the table cannot be used in mode 0, which is the boot up value for EBSR:PPMODE. Can you confirm?

2. In the C5504 system user guide, sprugh6a.pdf, table 1-43, for field PPMODE: the document says that the bits control multiplexing of certain peripherals and GPIO ports. The list of GPIO ports should (I think) include 12:17 as well as those listed. I think this applies to other C55x system user guides, such as C5505. Can you confirm?

3. May EBSR be re-written after a software reset, or is it necessary for a hardware reset to occur before EBSR can be written a second time?

  • 0
    TI__Prodigy 270 points

    Thanks for the questions, John. My answers to each are:

    1. Good point about being clear regarding Mode 0 in the EBSR:PPMODE table. We will add this column to the C5515/14/05/04 datasheets in our next update.

    2. Your assumption is correct. We will also add GPIO[17:12] to the description of the EBSR Register in each System user guide when we update.

    3. I'll check on this answer and get back to you. We can clarify this in our update as well.

    Best regards.

  • 0
    TI__Prodigy 270 points

    John Fisher said:

    3. May EBSR be re-written after a software reset, or is it necessary for a hardware reset to occur before EBSR can be written a second time?

    John, to follow up on your question here: A software reset should be fine to allow you to re-write to the EBSR. Just be sure that you're following the description in the System user's guide, SPRUGH6:

    "Before modifying the values of the external bus selection register, you must clock gate all affected peripherals through the Peripheral Clock Gating Control Register. After the external bus selection register has been modified, you must reset the peripherals before using them through the Peripheral Software Reset Counter Register."

    Let us know if anything about that is unclear.

    Regards,

  • 0 in reply to Theodore Wolff
    Expert 1030 points

    That's all clear, thanks. I'll take the word reset to mean software or hardware reset. I assume that in situations where there was a distinction between software and hardware reset, the documentation would make that clear.

    I'd mark this answered, but I can't. I think I might have started this thread as a discussion.