Am Sonntag, 2. Dezember 2007 05:48:23 schrieb Peter Stuge: > On Sat, Dec 01, 2007 at 07:46:14PM -0500, Richard Smith wrote: > > CS# from the IT8716F is routed up to R509 which is a zero ohm > > resistor. > > If this resistor is in place then CS is hardwired to CS# on U5 > > which is the SPI chip that's loaded. If you pull R509 then the CS# > > to both chips are free to be selected by (unloaded) Q2,Q43,Q4, and > > Q5 + resistors but I don't have the configuration mapped out. > > They would be part of Gigabyte's patented hardware BIOS failover > technology I suppose. > > Q4-3 and Q5-3 are both connected to the superio side of R509, so the > emitter if using PNP transistors. > > Traces from Q4-1 and Q5-1 both run toward the flash chips so they > would be the collector. > > Q4-2 and Q5-2 the base, with R91 before Q4 and R90 before Q5. The > other side of R91 goes to R389 which then goes to Q43-2. The other > side of R90 goes to R86 which then goes to Q2-2. > There are some vias on the traces between R{90,91} and Q{4,5} so they > are connected to something else as well. (But what?) There are also > vias on traces between R{86,389} and Q{2,43}. > > Q43 and Q4 are driven at the same time, through R389 and R91 > respectively. I wonder what the purpose of Q43 and Q2 is. > > The pinout does indeed match e.g. a BC847 PNP transistor in SOT23 > package. > > R89 is between Q4-1 (U5-CS#?) and a power net, so would be the > pull-up for when Q4 is not driven to select U5. > > There is certainly a corresponding resistor for Q5-1 but there's only > a via from the Q5-1 trace so it would have to be tested. My guess is > R130 (directly south of R129) since it's other end goes to U9-CS#. > > > It does not look like there is any easy way to re-enable switching > > between the SPI chips since you have to load several missing parts. > > The switch mod can be simplified to use existing pads and no pins > have to be lifted from the flash chips anymore. > > 1. Remove R509. > 2. Populate R89 and R130 with 10k or 100k pull-up 0402 resistors. > 3. Solder the switch common to Q4-3 and switch between Q4-1 and Q5-1. Confirmed. But not with SMD Resistors.
First I removed the R509. As there are connections from R89 Left to U5 VCC; from R89 Right to U9 CS#; from R130 Left to U5 CS# and from R130 Right to U9 VCC I soldered normal 100k resistors between U5 VCC and U9 CS# and between U5 CS# and U9 VCC. Here are two photos of my new mod: http://img141.imageshack.us/img141/8866/dscf1791ob2.jpg http://img104.imageshack.us/img104/2579/dscf1792nn2.jpg I know, that these cables to the sockel are not really fine, but i had no other solution for mounting the sockel on the mainboard and it works fine! I added a sockel for the SPI-chips to be able to change the bios chip in an easy way. If someone is interested which sockels these are, they are manufactured by WELLS-CTI and have the part number 652C0082211-W003. I payed about 8€ per part, and that sould be about 10$, without shipping costs. The distributer for these sockels was http://www.bfioptilas.com/. (PS: thanks to Mr. A. v. Heydwolff for organising these sockels.) > Of course this assumes that soldering 0402 resistors is considered > simple, which isn't likely true unless you're good at SMT soldering. A friend of mine helped me with the soldering, but he said that it is nearly impossible to solder these resistors without industry-equipment. > > > I'll probably just end up soldering on a 2nd chip and then wiring > > the CS# pins up to a switch like the other mods did. > > Of course there could be some timer thingy to do failover, but I > think manual control is best. I think the spring-loaded switch is > as useful as any mechanism in this case. > > > //Peter -- linuxbios mailing list linuxbios@linuxbios.org http://www.linuxbios.org/mailman/listinfo/linuxbios