Re: [U-Boot-Users] AT91 Bootstrap in U-boot
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@lists.sourceforge.net [mailto:u-boot-users-bounces@lists.sourceforge.net] On Behalf Of Ulf Samuelsson Sent: Wednesday, February 13, 2008 15:16 To: E Robertson; u-boot-users@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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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?
If you check the schematics, you will find "not mounted" on the 4 MB parallel flash. I doubt that there has been any significant number of AT91SAM9 kits shipped with this mounted.
The original question was why AT91bootstrap was not ported to U-boot, and the focus from the S/W group is on dataflash and NAND flash support. This is also what most customers (that I know of) are using.
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.
They can, by adding a PCB to the EBI connector. There has been some progress here on the S/W side, but I am still waiting for the release.
Sincerely,
Ken Fuchs
Best Regards Ulf Samuelsson
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Ulf Samuelsson