System Management Bus

hardware, protocol (SMBus, SMB) A simple two-wire bus used

for communication with low-bandwidth devices on a motherboard,

especially power related chips such as a laptop's rechargeable

battery subsystem (see Smart Battery Data). Other devices

might include temperature sensors and lid switches.

A device can provide manufacturer information, indicate its

model/part number, save its state for a suspend event,

report different types of errors, accept control parameters,

and return status. The SMB is generally not user configurable

or accessible.

The bus carries clock, data, and instructions and is based on

Philip's I2C serial bus protocol. Support for SMBus devices

is provided on Windows 2000. Windows 98 does not support

such devices.

The PIIX4 chipset provides SMBus functionality. Vendors

using SMBus would be required to pay royalties.

SMBus website.

Software to interrogate a SMB motherboard.

SMB devices, Part 8 Kernel Mode Driver Design Guide, Win2000 DDK.

(1999-08-08)