Modify/Change/Overwrite Bootloader

asd asd

Hi,

Is it possible to modify/change/overwrite the Bootloader in C553x family devices? Literature SPRUH87C states:

The standard device includes a bootloader program resident in the ROM and the bootloader code is
executed immediately after hardware reset. When the MPNMC bit field of the ST3 status register is set
through software, the on-chip ROM is disabled and not present in the memory map, and byte address
range FE 0000h - FF FFFFh is unmapped. A hardware reset always clears the MPNMC bit, so it is not
possible to disable the ROM at hardware reset. However, the software reset instruction does not affect the
MPNMC bit. The ROM can be accessed by the program and data buses. Each SAROM block can perform
one word read access per cycle.

Does this mean the bootloader can be overwritten/modified through using Code Composer? If so, does TI provide the source code of the bootloader? I would like the device to enter low power mode if no boot sequence is found. However, I couldn't find any resources regarding modifying the bootloader.

Thanks in advance,

John

over 12 years ago

0 Bill Finger over 12 years ago

Genius 3735 points

ROM stands for Read Only Memory, so by definition it cannot be modified.

However, I have found that it is very easy to create your own secondary bootloader. Just have the ROM bootloader load yours, then have yours do whatever you want (such as boot from unsupported devices).

0 asd asd over 12 years ago in reply to Bill Finger

Intellectual 360 points

That's a good idea. What resources are there to creating a secondary bootloader and booting from eg an supported device? I don't recall finding anything about this.

Thanks!

0 Bill Finger over 12 years ago in reply to asd asd

Genius 3735 points

The 'C5535 doesn't talk much about the bootloader, but I believe that the 'C5515 bootloader is identical, at least wrt loading code. See sprabd7a. It documents the format of the bootloader file, and hence what needs to be done to load the code into memory.

0 asd asd over 12 years ago in reply to Bill Finger

Intellectual 360 points

Thank you so much!

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Modify/Change/Overwrite Bootloader