[U-Boot-Users] AT91 Bootstrap in U-boot

Ken.Fuchs at bench.com Ken.Fuchs at bench.com
Thu Feb 14 17:07:59 CET 2008


Ulf Samuelson wrote:

> There are no Atmel AT91SAM9 dev boards which uses a parallel flash.

This is not quite true.  I'm able to boot a AT91SAM9263-EK board via EBI
NOR flash and an AT91Bootstrap/Atmel modified U-Boot right now.  Did I
misunderstand your statement above?

One needs only to solder an appropriate EBI NOR chip to the
AT91SAM9263-EK board and install the BMS jumper to allow parallel flash
booting.  Unfortunately, the boards in the AT91SAM9260-EK and
AT91SAM9261-EK can't support an EBI NOR flash due to intentional design
limitations.

Sincerely,

Ken Fuchs

> -----Original Message-----
> From: u-boot-users-bounces at lists.sourceforge.net 
> [mailto:u-boot-users-bounces at lists.sourceforge.net] On Behalf 
> Of Ulf Samuelsson
> Sent: Wednesday, February 13, 2008 15:16
> To: E Robertson; u-boot-users at lists.sourceforge.net
> Subject: Re: [U-Boot-Users] AT91 Bootstrap in U-boot
> 
> 
> > Hi,
> > Is their a reason why the AT91 Bootstrap code was never ported to
> > U-boot?
> 
> Yes, Integrating AT91Bootstrap only makes sense if you have a 
> parallel flash.
> 
> There are no Atmel AT91SAM9 dev boards which uses a parallel flash.
> The AT91RM9200 boards uses parallel flash, but they do not 
> use AT91Bootstrap.
> 
> The SAM9 boards all have an AT45 dataflash which has an SPI interface.
> The BMS pin needs to be configured to make the CPU boot from 
> the internal BootROM.
> The BootROM copies the initial application at address 0 of 
> the dataflash to internal SRAM.
> The SRAM can be as small as 4 kB (in the AT91SAM9260) and 
> that limits the functionality.
> U-Boot does not fit, so you have AT91bootstrap.
> 
> AT91bootstrap needs to run BEFORE U-Boot is started.
> 
> 
> Best Regards
> Ulf Samuelsson
> 
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