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CCS/TMS320F28377S: How can I setup TMS320F28377S Boot pin function switch to GPIO after system booted up?

roger zeng
Prodigy 230 points
Part Number: TMS320F28377S


Tool/software: Code Composer Studio

Hello Guys:

I am working on TMS320F28377S platform for a instruments project, I have selected QFP176 package for this application, In my system there is a FPGA working with the DSP, I need EMIF1 port of DSP to connect with FPGA, So I have met a question which is EM1D12 (I/O) function is also mapped GPIO72 (Boot pin)function, If device boot from Flash I need set the boot mode as the get mode It means GPIO72 need pull up to VCC3.3V with a 1K resister, But when I use EM1 port as the data communication port I can not hold the D12 in 3.3V, So are there any way to work around this issue???

Thanks

RZ

  • 0
    TI__Guru** 115431 points
    Roger,

    After device boot, BOOTPINS can be mapped to other functions. So in your application you can change the GPIO mux setting to use it as EMIF pins, no issue with that.

    Regards,
    Vivek Singh
  • 0 in reply to Vivek Singh
    TI__Guru** 115431 points
    and having external weak pull-up on the pin should not impact EMIF functionality.
  • 0 in reply to Vivek Singh
    Prodigy 230 points
    Hi, Vivek! Is the 10K resister suitable for weak pull-up ???
  • 0 in reply to roger zeng
    TI__Expert 5520 points
    Roger,

    The answer will depend on your application and specific PCB layout. You can use the IBIS models available on the tools and downloads page together with signal integrity PCB software to ensure the 10k will not interfere with the interface. On the other end of the question, the strength of the pull down will depend on how much noise your system will see during power up which might allow the wrong boot mode to be activated.

    With the above in mind, in general a 10K sounds reasonable; assuming you have an otherwise well designed connection to the external memory device and do not expect a noisy supply during power up. I wouldn't use much weaker than 10K though, maybe a 4k could also work depending on your application.

    Best regards,
    Jason