• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 3 answers
  • Subscribers 65 subscribers
  • Views 443 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CCS/UCD3138: what does "pmbus_read_write_rom_mode(PMBUS_WRITE)" mean in main.c

David yang
Prodigy 50 points
Part Number: UCD3138

Tool/software: Code Composer Studio

In the UCD3138LLCEVM-028 code, in main.c there is a code copied below, what does it mean?

//Check to see if FAULT2 is pulled high and FAULT0 is pulled low.
//If they are go to ROM.
if (MiscAnalogRegs.GLBIOREAD.bit.FAULT2_IO_READ && !MiscAnalogRegs.GLBIOREAD.bit.FAULT3_IO_READ)
{
pmbus_read_write_rom_mode(PMBUS_WRITE);
}

  • 0
    TI__Mastermind 18370 points

    As you probably know UCD3138 has a ROM bootloader.

    After power up UCD3138 always start executing ROM. ROM with check the content of program Flash(PFlash) vs. the PFlash checksum and if everything OK, it will start executing your firmware in the PFlash.

    The function pmbus_read_write_rom_mode sends the UCD3138 back to execute ROM, so you will be able to download a different firmware using the ROM bootloader and PMBus.

    This function sends to ROM by clearing the checksum and perform a software reset.

    The if part in the code that you pasted is looking at the combination of status of two GPIO lines (FAULT2 and FAULT3) to decide whether to act or not.
    This if condition should not be TRUE during normal operation of firmware. Only if you want to use the GPIO pins to go back to ROM, you can hold the pins in the proper state.

    Hope this makes sense.

    If above addresses your question please set the status of this post to resolved.

    Regards,

  • 0 in reply to Yitzhak Bolurian
    Expert 1515 points

    Hi Yitzhak,

    I noticed that there 2 ways for triggering mcu reset after the clearing checksum function was done by case 12 between latest code and previous code, may I know why it uses triggering software reset instead  point function to illegal address, thanks.

  • 0 in reply to HAN LEE
    TI__Mastermind 18370 points

    The use of SysRegs to apply a software reset the better choice!

    The first option tries to force an exception by accessing an illegal location.

    That in turn will cause a reset. But the second option is preferable.

  • 0 in reply to Yitzhak Bolurian
    TI__Mastermind 18370 points
    If the above addresses your question, please set the status of this post to resolved.
    Regards,