[U-Boot-Users] Re: Installing U-Boot on target via USB/serial using U-Boot commands
Andrey P. Vasilyev
andrey_vasilyev at mail.ru
Mon Sep 26 19:21:29 CEST 2005
On Mon, Sep 26, 2005 at 09:24:39AM -0400, Jerry Van Baren wrote:
> It looks like this is a very simple loader. It writes to SRAM _only_
> and then jumps to that program (JTAG loaders typically allow you to
> write to flash, manipulate registers, and jump anywhere, single step,
> etc.). Theoretically you could load u-boot this way, but nobody has
> volunteered that they have done it so you would likely be blazing a new
No, it is an ordinary (and supported by Atmel) way to bootstrap an
AT91RM9200 boards having only a simple COM-port cable :)
> My advice would be to write a simple "burn flash" routine (it can be
> done in a couple dozen lines of assembly - don't get elaborate) ORGed at
> the start of SRAM and prepend it to the u-boot image. Your USB loader
Atmel have such a simple utility called RomBoot. It acts as a simple
first-stage bootloader, and allows to set up SDRAM and PLLs,
load U-Boot from DataFlash or (by X-Modem) from DBGU UART and passing
control to it.
> (I'm guessing the target side looks like a simple usb-UART) would load
> the burner utility and the u-boot image as a single lump and jump to the
> burner utility. The burner utility would program the u-boot image from
> SRAM into flash. Reset the board and you are off & running.
> If your first attempt doesn't work, you are in the "burn & learn" cycle.
> This can be successful if your image is close to working and you have
> a fair amount of experience, or it can be an infinite time suck. If the
> latter is the case, a JTAG debugger is invaluable.
I'm using a simple jumper on the board for turning DataFlash chip into
reset state while booting. This allows to boot from DBGU serial port
when DataFlash contains a valid but non-working image.
With best regards,
More information about the U-Boot