System Management Bus
is a two-wire interface through which simple power-related chips can communicate
with rest of the system.
It uses I2C as its backbone (see
A system using SMB passes messages to and from devices instead of tripping
individual control lines.
With the SMBus, a device can provide manufacturer information, tell the
system what its model/part number is, save its state for a suspend event,
report different types of errors, accept control parameters, and return its
The SMBus may share the same host device and physical bus as ACCESS bus
components provided that an appropriate electrical bridge is provided
between the internal SMB devices and external ACCESS bus devices.