SMBus: a viable alternative for motherboard diagnostic codes?

[japlytic]

You may have noticed that a number of chipsets and motherboards no longer include parallel PCI slots, but instead, only PCI Express slots are available.
One thing I have noticed on the standard PCI Express and Mini-PCI Express slots is the presence of the SMBus signals.
The LPC bus (which can output POST/diagnostic codes) is a bit hard to tap into, since you would need to know the location of these signals.

So even on a motherboard with PCI Express (standard and mini) slots, the use of a diagnostic card which uses the SMBus is quite viable for obtaining POST/diagnostic codes from the motherboard, provided the motherboard can output these codes to the SMBus.

I may have seen diagnostic code readers which tap into the SMBus on the Smart Battery connector on notebooks some time ago on eBay.

[eccerr0r]

Re: SMBus: a viable alternative for motherboard diagnostic codes?

All depends on the firmware. If they don't dump the codes somewhere as a standard, then it's not viable. Plus the fact that iic/smbus controllers are not standardized as much as port 0x80 which is a very well defined standard (though obsolete as this is for ISA, and yes this is on LPC.)

Plus the fact that more than one iic bus can be available on any particular machine - which one will have the diagnostic codes.

I think my IA64 box actually does output diagnostic codes to IIC. I unfortunately do not have the chip to display them...