[LinuxBIOS] SPI flash focus

[Drew Lundsten]

</lurk>

Is anyone else focused on hardware approaches to SPI flash programming?

I know this is an inexorable push and welcome it from the layout
perspective, but finding a way to rewrite SPI-flash BIOS in place is an
interesting challenge.

My thoughts to present are to overdrive (temporarily) the signals using
a SO-8 clip and maybe an ACT buffer, but obviously it's not as optimal
as a BIOS Savior. JTAG would be better where supported, but I don't see
a general solder-free approach.

Off-reflector replies welcome.

<lurk>

Drew Lundsten  [phone]/619-895-1764 cell
Continuous Computing Corporation, 9380 Carroll Park Dr, San Diego 92121

[Carl-Daniel Hailfinger]

Drew Lundsten wrote:
> Is anyone else focused on hardware approaches to SPI flash programming?
>
> I know this is an inexorable push and welcome it from the layout
> perspective, but finding a way to rewrite SPI-flash BIOS in place is an
> interesting challenge.
>
> My thoughts to present are to overdrive (temporarily) the signals using
> a SO-8 clip and maybe an ACT buffer, but obviously it's not as optimal
> as a BIOS Savior. JTAG would be better where supported, but I don't see
> a general solder-free approach.

Are you looking for something like this? Seems to be solder-free.
http://www.dediprog.com/product.php?UID=12

Regards,
Carl-Daniel

[Peter Stuge]

On Fri, Nov 24, 2006 at 04:53:03AM +0100, Carl-Daniel Hailfinger wrote:
> Are you looking for something like this? Seems to be solder-free.
> http://www.dediprog.com/product.php?UID=12

Unfortunately it requires some special characteristics in the board
schematic, to not risk destroying the chipset.

"Warning: please do not try to use SF100 directly on the application
system if the scenario is not in the above two cases."

..from their manual. I agree with them, it could be dangerous to
drive the SPI chip while it's connected if you don't know exactly how
it is connected and that it really is safe on that particular board..

//Peter

[Peter Stuge]

On Fri, Nov 24, 2006 at 08:33:02AM +0100, Peter Stuge wrote:
> ..from their manual. I agree with them, it could be dangerous to
> drive the SPI chip while it's connected if you don't know exactly
> how it is connected and that it really is safe on that particular
> board..

That said, we may end up doing it anyway. Look at hotswapping flash.
:)

//Peter

[Segher Boessenkool]

> Unfortunately it requires some special characteristics in the board
> schematic, to not risk destroying the chipset.
>
> "Warning: please do not try to use SF100 directly on the application
> system if the scenario is not in the above two cases."
>
> ..from their manual. I agree with them, it could be dangerous to
> drive the SPI chip while it's connected if you don't know exactly how
> it is connected and that it really is safe on that particular board..

The only thing that is required is that they can safely pull the
HOLD# pin to ground.  Any sane design will have a pull-up resistor
on that line (and most other SPI lines, for that matter).  That
said, there probably _are_ boards that do not have a sane design.
Such a shame.

[Oh, it obviously also doesn't work if the chipset or the motherboard
design uses HOLD# for something else already.  This isn't commonly
done though].

Aaaaaanyway...  It is really simple to build a device like this
yourself for a few bucks.  SPI flash has many nice characteristics.

Segher