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About ROM BOOT LOADER

Hiroyasu Tazawa1
Guru 12350 points

Hi, Everyone

I have a question about TM4C129x ROM Boot Loader.
We can not jump ROM Boot loader.

Data sheet says

1. The BOOTCFG register is read. If the EN bit is clear, the ROM Boot Loader is executed.
2. In the ROM Boot Loader, the status of the specified GPIO pin is compared with the specified
polarity. If the status matches the specified polarity, the ROM is mapped to address 0x0000.0000
and execution continues out of the ROM Boot Loader.

and I tested like this.

BOOTCFG register is FFFFFFFE.
PH7 is High.

Do you know why We can not jump ROM Boot loader?

Best Regards
Hiroyasu

  • 0
    TI__Mastermind 22580 points
    Hello Hiroyasu,

    From what I understand, you want to configure the BOOTCFG register such that during power-on the ROM Bootloader should execute when a GPIO is asserted. Is this correct? If yes, then the value you mentioned (FFFFFFFE) will not work.

    The EN bit (i.e. bit 8) should be cleared (or written to 0). Only then the ROM Bootloader will check if a registered GPIO (identified by the bits 13:15 of BOOTCFG register for the GPIO Port and bits 10:12 for the specific pin) is asserted (idnetiifed by bit 9 of BOOTCFG register). If the GPIO is asserted, then the ROM Bootloader continues to execute. If the GPIO is not asserted, the ROM Bootloader will check if a valid image is present in the flash and boot it.

    Thanks,
    Sai
  • 0 in reply to Sai Reddy
    Guru 12350 points
    Hi,Sai

    Thank you for your reply.
    I got it.

    Best Refards
    Hiroyasu