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From: Grant Edwards on 13 Jan 2010 16:27
On 2010-01-13, Stef <stef33d(a)yahooI-N-V-A-L-I-D.com.invalid> wrote:

>> Where do you plan to store your code to load into the ram?
>> Most systems use dataflash for storing boot code and parallel
>> Flash for the full application, although there is no reason
>> why you can't use the dataflash for the full application if it
>> is not too large. 64 KB shouldn't be a problem.
>
> Dataflashes are available in much larger sizes and since he
> wants SDRAM, I suspect that will be at least several MB large.
> So booting from dataflash and copying code to SDRAM should
> also not be a problem for >MB apps. (you may have to write
> some second level loader code yourself, the standard loader
> may only load a few KB to get you started).

The bootloader built in to the AT91SAM9 parts will only load
into internal SRAM (typically 8 or 16KB). That means you need
a small second-stage bootloader than enables/configures SDRAM
and copys either your application or a larger bootloader (e.g.
U-Boot) into SDRAM and executes. Atmel provieds a sample
bootloader than is set up to load U-Boot from dataflash,
nand-flash, nor-flash, SD-Card, etc.

--
Grant Edwards grante Yow! I am having FUN...
at I wonder if it's NET FUN or
visi.com GROSS FUN?
From: aleksa on 13 Jan 2010 17:30
> It's a big CPU world out there. No reason to limit yourself to one
> manufacturer.

You are absolutely right, thanks.


From: aleksa on 13 Jan 2010 17:53
> Where do you plan to store your code to load into the ram?

In a 2MB dataflash (which already is on-board)


> You haven't said anything about the requirements of your project.

I really forgot that, and it's important.

The original code runs well on PI @ 166MHz, so I need something close to that.
Big part of x86 code uses FPU.

Besides SDRAM pins, I need some 30 I/O pins.
(5V tolerance is always good, but not required)


From: Stef on 13 Jan 2010 18:01
In comp.arch.embedded,
Grant Edwards <invalid(a)invalid.invalid> wrote:
> On 2010-01-13, Stef <stef33d(a)yahooI-N-V-A-L-I-D.com.invalid> wrote:
>
>> Dataflashes are available in much larger sizes and since he
>> wants SDRAM, I suspect that will be at least several MB large.
>> So booting from dataflash and copying code to SDRAM should
>> also not be a problem for >MB apps. (you may have to write
>> some second level loader code yourself, the standard loader
>> may only load a few KB to get you started).
>
> The bootloader built in to the AT91SAM9 parts will only load
> into internal SRAM (typically 8 or 16KB). That means you need
> a small second-stage bootloader than enables/configures SDRAM
> and copys either your application or a larger bootloader (e.g.
> U-Boot) into SDRAM and executes. Atmel provieds a sample
> bootloader than is set up to load U-Boot from dataflash,
> nand-flash, nor-flash, SD-Card, etc.

Ah yes, now I remember (amazing how soon you forget that stuff if
you're not working on it anymore). The one we use has 16KB of
internal SRAM. But make sure you limit the first load to somewhere
around 12K. The ROM bootloader uses the upper part of the SRAM for
it's variables and other stuff. If you get in that area the result
gets 'unpredictable'. (mostly just hangs up).


--
Stef (remove caps, dashes and .invalid from e-mail address to reply by mail)

Freedom of the press is for those who happen to own one.
From: aleksa on 13 Jan 2010 18:11
> Dataflashes are available in much larger sizes and since he wants SDRAM,
> I suspect that will be at least several MB large.

Actually, my code is some 64k, but the dataflash is already on-board,
so making it a boot device for '9260 is a logical step.

Run-time data can be some 16MB, that's why I need SDRAM.


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