System Management Bus
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The System Management Bus (abbreviated to SMBus or SMB) is 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 SMBus is generally not user configurable or accessible.
The bus was defined by Intel in 1995. It carries clock, data, and instructions and is based on Philips' I²C serial bus protocol. Its clock frequency range is 10 kHz to 100 kHz. Its voltage levels are different from those of I²C, but devices belonging to the two systems are often successfully mixed on the same bus. The SMBus has an extra optional signal called ALERT#, which can be used by slaves to send an interrupt request to the controller.
Linux, Windows 2000, and Windows XP support SMBus devices, but Windows 98 does not.
External links
- This article was originally based on material from the Free On-line Dictionary of Computing, which is [Foldoc licenselicensed] under the GFDL.
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