System Management Bus

System Management Bus

The System Management Bus (abbreviated to SMBus or SMB) is a simple two-wire bus, derived from I²C and 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, fan, or voltage sensors; and lid switches. PCI add-in cards may connect to an SMBus segment.

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. Although SMBus devices usually can't identify their functionality, a new PMBus coalition has extended SMBus to include conventions allowing that.

The SMBus 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. (PMBus extends this to 400 kHz.) Its voltage levels and timings are more strictly defined than those of I²C, but devices belonging to the two systems are often successfully mixed on the same bus.

SMBus is mostly a subset of I²C; more loosely specified I²C devices may cause an SMBus to hang. The SMBus has an extra optional shared interrupt signal called SMBALERT#, which can be used by slaves to tell the host to ask its slaves about events of interest.SMBus also defines a less common "Host Notify Protocol", providing similar notifications but passing more data and building on the I²C multi-master mode.

FreeBSD, Linux, Windows 2000, Windows XP and Windows Vista support SMBus devices, but Windows 98 and earlier versions do not.

External links

* [http://www.smbus.org/ SMBus website]
* [http://www.sbs-forum.org/ SBS forum]
* [http://www.tech-faq.com/smbus.shtml SMBus at tech-faq.com]


Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • System Management Bus — System Management Bus,   SMB …   Universal-Lexikon

  • System Management Bus — Este artículo o sección necesita referencias que aparezcan en una publicación acreditada, como revistas especializadas, monografías, prensa diaria o páginas de Internet fidedignas. Puedes añadirlas así o avisar …   Wikipedia Español

  • System Management Bus — Der System Management Bus (abgekürzt SM Bus, SMBus oder SMB) ist ein Zweileiterbus, der für die Baugruppenkommunikation entwickelt wurde (besonders für Halbleiter ICs). Er hilft, den Zustand von Komponenten zu erkennen und Hardwareeinstellungen… …   Deutsch Wikipedia

  • Bus transport in Singapore — is the most comprehensive and affordable means of public transport for the masses, with over two million rides taken per day on average on the buses of the two main public transport providers SBS Transit and SMRT Corporation. There are more than… …   Wikipedia

  • System integration — is the bringing together of the component subsystems into one system and ensuring that the subsystems function together as a system. In information technology, systems integration is the process of linking together different computing systems and …   Wikipedia

  • Bus encryption — is the use of encrypted program instructions on a data bus in a computer that includes a secure cryptoprocessor for executing the encrypted instructions. Bus encryption is used primarily in electronic systems that require high security, such as… …   Wikipedia

  • IIC-Bus — I²C (für Inter Integrated Circuit, meistens gesprochen als I Quadrat C oder englisch I squared C) ist ein von Philips Semiconductors entwickelter serieller Datenbus. Er wird hauptsächlich geräteintern für die Kommunikation zwischen verschiedenen… …   Deutsch Wikipedia

  • I²C-Bus — I²C (für Inter Integrated Circuit, meistens gesprochen als I Quadrat C oder englisch I squared C) ist ein von Philips Semiconductors entwickelter serieller Datenbus. Er wird hauptsächlich geräteintern für die Kommunikation zwischen verschiedenen… …   Deutsch Wikipedia

  • Inter Integrated Circuit Bus — I²C I²C (pour Inter Integrated Circuit Bus) est le nom du bus historique, développé par Philips pour les applications de domotique et d’électronique domestique au début des années 1980, notamment pour permettre de relier facilement à un… …   Wikipédia en Français

  • Bus transport in the United Kingdom — Buses play a major role in the public transport of the United Kingdom, as well as seeing extensive private use.History The horse bus era The first omnibus service in the United Kingdom was started by John Greenwood between Pendleton and… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”