[ECOS] Reg: Redboot porting For AT91SAM7A3

Andrew Lunn andrew@lunn.ch
Thu Mar 16 09:26:00 GMT 2006


On Thu, Mar 16, 2006 at 02:37:44PM +0530, jagannath wrote:
> Hi, 
>       I am using ecos for AT91SAM7A3. This is somewhat similar to
> AT91SAM7S. So i am using ecos ported for AT91SAM7S, with a slight
> modifications for my hardware. I compiled ecos for AT91SAM7A3.
> 
> Now i want to port redboot for this.My Ram is 32K and flash is 256K
> only.
> 
> 1. Can i use ROM-RAM boot mode, or i have to use only ROM mode.?

It makes little sense to use ROMRAM. You have so little RAM why waist
it with Redboot? These processors are designed to run the application
from ROM.

Question: Why do you want redboot? I've been using the AT91SAM7S256 a
lot recently. I never use Redboot. I just write ROM applications and
use a JTAG programmer to put them straight into ROM. You cannot reaaly
use Redboot for debugging since it does not understand hardware
breakpoints. You need to debug using the JTAG port.

> Previously i worked for MPC850.So i was using srec image for both
> redboot and my application. But after compilatation, i am getting 
> ELF32 image.
> 
> 2. I want to know, which type of image i hace to use.Is it required to 
> use srec image or the elf image.But srec image is the motorola format.
> I think i cant use this format image for ARM processor.

SREC is valid for all processor architectures. Look at the man page
fom objcopy. It tells you how to convert an elf into an srec file.
However most jtag programmers understand elf, so most of the time you
don't need srec.

> 3. A redboot_rom.elf is available for redboot for ARM target.Can i use
> this image for my controller or i need to compile the redboot again.

You need to compile a redboot image for your specific target. 
 
> 4.I have used gnu tool chain for ARM for compiling the eCos.Is it the
> correct one or i need to build the tool chain for thumb.

I've used the ARM instruction set for the AT92SAM7S and it works. You
could use thumb if you want, it might produce smaller binaries. It is
your choice.

        Andrew

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