Re: [ECOS] External SRAM on EB40a

[Andrew Lunn <andrew dot lunn at ascom dot ch>]

On Tue, Jul 01, 2003 at 02:01:26PM +0200, Ketil Harald Ruud wrote:
> 
> I have an AT91EB40A evaluation board equipped with external SRAM (SAMSUNG
> k6r4008v1c, (512Kx8bits)x2).
> 
> Redboot is loaded to upper half of flash at address 0x01100000. (Redboot can
> also run from on-chip SRAM.)
> 
> Can anybody tell me what kind of modification that are required to access
> the external RAM? When I try to load the hello-world application to external
> RAM, Redboot keeeps telling me that there is no RAM at address 0x2000000 and
> refuses to load.
> I have used "configtool" to generate the ecos application.

You can force redboot to load even though it thinks there is no memory
there. It should ask you this.

You can also disable CYGSEM_REDBOOT_VALIDATE_USER_RAM_LOADS so that it
does not even check.

Redboot is not so good with discontinuous memory. It assumes RAM is
all in one block when performing checks. So disabling the check is
probably a good move anyway.

Does the SRAM need any initialization? I could not see anything in the
EB40a to do the initialization? Even if you do tell redboot to
continue it might still fail because the MMU thinks there is no memory
there and throws an bus error. (Im assuming the EBA40a actually has a
MMU. I know nothing about this HW!).

     Andrew

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