[En-Nut-Discussion] Boot Loader

[Dave Warren]

Hi Ben,

I think I will modify your idea a little, the Atmel SAM7X256 EK board has a 
socket for a dataflash card. Perhaps that is the place to store a downloaded 
image. I could even use the nut/os file routines to save the binary files.

The problem that might be the most difficult is the start up of either the 
bootloader or the normal nut/os application. Do you have your bootloader 
working with nut/os?

I guess that on power up the bootloader would first run, it would check the 
files on the dataflash and in internal flash and decide if an update of the 
internal flash is required. After any update it would exit and some how 
start the nut/os application. The nut/os application includes a way to 
download new binary files to the dataflash. In addition files could be 
updated by plugging the dataflash into a memory card reader on a PC. The 
bootloader would be in a protected area of internal flash so it is always 
safe.

Did you say your bootloader runs from RAM? How do you link the bootloader 
and application to get then to start up?

regards

Dave

----- Original Message ----- 
From: "Ben Hoyt" <benhoyt at gmail.com>
To: "Ethernut User Chat (English)" <en-nut-discussion at egnite.de>
Sent: Thursday, October 12, 2006 10:09 PM
Subject: Re: [En-Nut-Discussion] Boot Loader


> Hi Dave,
>
> I've used the AT45DB041B (4 Mbit) and the AT45DB161D (16 Mbit) parts. They
> talk almost exactly the same way, though the page sizes are 256 bytes and
> 512 bytes, respectively. It may be slightly simpler to have your DataFlash
> page size match the SAM7 flash page size.
>
> The challange is to get the bootloader to be small enough yet still 
> include
>> some basic ethernet functions, I think one16K flash page may not be
>> enough.
>
>
> I reckon you could do a simple ethernet/TFTP bootloader in 16 KB, possibly
> even remotely with a cellular modem. Though I've never tried, as I kinda
> feel it's the wrong way of going about it.
>
> Can you send me your bootloader project please.
>
>
> Unfortunately I can't really. The old "Commercially Sensitive Information"
> thing. :-) I can answer any general questions you have, though.
>
> Cheers,
> Ben.
>
> -- 
> Ben Hoyt
> Mobile: +64 21 331 841
> http://www.benhoyt.com/
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