[LinuxBIOS] different versions of the GA-M57SLI-S4 (PLCC vs SPI)

[echelon at free.fr]

Quoting Peter Stuge <peter at stuge.se>:

> On Sat, Sep 01, 2007 at 10:13:21PM +0200, Carl-Daniel Hailfinger wrote:
> > >> SPI detection/flashing support is on my list.
> > >
> > > Is the SPI flash connected to the sio on the m57sli?
> >
> > No idea.
>
> So we should find out.
>
> Ward - do you have a continuity tester? Could you see if the SPI
> flash chip is connected to the Super IO?
>
> If I get a high-res photo of the Super IO and the flash chip area I
> can mark the pins that should be connected on both to get a yes/no
> indication.
>

Hi Peter,

 The spi clock signal (SCK - pad 25 of the SIO) doesn't seem to be directly
connected to the pad 6 of the bios spi chip.. One could think that there is a
serial resistor between them (for signal integrity) but when I measure the
resistance value between the 2 nodes I find values greater than 1 kohm.. I think
that for the operating frequency (I measured 25 MHz for this signal with the
scope on the bios chip pad), if there was a serial resistor it should had much a
much lower value (maybe something like 50 ohm f.ex..) Please, someone with
better electronics background can correct me if Im wrong on this topic?
 Also when studying the board with a powerfull magnifying glass around the sio
chip, one can see that the trace starting on the pad 25 apparently ends with a
unpopulated smt resistor (?) footprint. In fact, there is also a via connected
to this signal, but here I have no way figuring where this signal go trough this
via. (btw, as a joke, has someone here a good friend which is tooth physician or
radiologist to do a X-ray radiography of this board? ;-) )
 Now, back to my investigations..
  Florentin