[En-Nut-Discussion] Boot Loader

[Dave Warren]

Hi Tim,

I am using the SAM7X256 also. You are right a ethernet bootloader would be 
cool.

I have written a CAN bootloader in the past for the AVR micro (not using 
ethernut). What I think is important is that the bootloader itself can not 
be destroyed, that way you can aways use the bootloader to restore a node 
even after a 'bad' download. The bootloader would have to be a ethernut that 
was linked and run at a different address. It should run first at power up, 
normally it should switch to the application, another ethernut linked to a 
different address in Flash. However if you want to download then use it 
Flash the application instead.

Questions:-
1. Can you access a different Flash page while erasing or programming 
another page? If not the bootloader has to run from RAM, otherwise it locks 
up when the ARM tries to read the next program instruction.

2. Is there a seperate boot page in the Flash ?(Like AVR micros)

I don't know so much about the ARM or ethernut but would be willing to help.

regards

Dave Warren

----- Original Message ----- 
From: "Tim DeBaillie" <debaillie at ciholas.com>
To: <en-nut-discussion at egnite.de>
Sent: Monday, October 09, 2006 2:00 PM
Subject: [En-Nut-Discussion] Boot Loader


>
> I have an application on the AT91SAM7X256 using telnet.  I would like to 
> add an optional boot loader.  I was interested to hear if anyone has 
> attempted to write a boot loader for this version of ethernut on this 
> board or would be interested in helping develop such a thing.
>
> I believe the starting point is deconstructing the at91_efc.c file into a 
> set of functions or a driver that would allow for full flash memory 
> access.
>
> Comments?
>
> Tim
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