Minimal system for at91sam9*

>>Can I do away with NAND ?

If you need smallest physical size, then you can go with Atmel Serial DataFlash.

NAND-Flash provides the highest amount of storage in a small space.

The BOOT ROM provides many ways to boot up the AT91SAM9261, see Figure 13-1 in the datasheet.

>>Is the sam9 capable of booting NOR directly ?

Yes, the BMS pin determines if it starts up from internal BOOT ROM or external memory (i.e. NOR Flash).

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There are pro's and con's to each boot method.

The advantage to booting with NOR-Flash is that you can set a break point at beginning of the world.

The disadvantage of NOR-Flash compare to all the serial chips is physical size.

The boot loader only works by loading code into internal RAM because most external chip select aren't initialized yet and attached SDRAM won't be setup and configured yet.

I did one project with NOR-Flash, then another project with Serial DataFlash. The DataFlash was a pain because you had to configure the debugger to wait for the dataflash to download the program into RAM first. It was a lot easier debugging with NOR-Flash in the system.

If I did another ARM project that didn't have internal flash, and I had enough PCB space, I would choose to boot up into NOR-Flash device. If the project allowed it, I would choose SD flash for my mass storage.

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