Hi all,

I have created a helloworld.bin and i was able to download it to the SPI flash through SAMBA and it works fine.

But, when i try to download the *.bin through my flash writer application it does not boot.
The difference i found is SAMBA overwrite a section of interrupt vector table of the reserve offset.
in my startup.s i have mentioned the reserve offset of interrupt vector table like this.
B . ; RESERVED

this particular part of the *.bin (4 bytes of vector table)file is modified by SAMBA while
downloading it to the flash.

Can somebody tell me the reason for this or let me know if i am wrong.

Regards,
Vipin.

The RomBoot loader sanity checks the code before jumping to it. The modified vector must contain the length of the image, or the max size of one of the SRAM banks. The size of the of the SRAM will depend on the part you are using. The other vectors are check for standard vectoring instructions. If the tests fail, RomBoot does not map SRAM to 0x00000000, and your code does not execute.

SAM-BA performs this vector modification as part of it's boot writing function, so that it will pass the RomBoot test.

Thanks for the reply.

So If I use my own code downloader (not SAMBA) should I modify the vector table (ie Reserve vector with the *.bin file size) before I download it to the Flash?

Is this the correct way to download the code or is there a better way? Pls suggest.

Vipin.

Remember that RomBoot is copying your code into SRAM from NAND or Serial Flash, if it doesn't meet the check it's not going to run it.

Your available choices would appear to include :

a) Change the 6th vector to be the length before download, like SAM-BA
b) Set the 6th vector to a constant in your assembler code
c) Construct the 6th vector content in assembler so that when fixed up by the linker it becomes the length.
d) Run a post-link step which fixes the 6th vector.

Thanks a lot...