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Retreived from http://www.xbox-linux.org/wiki/SMBus_Controller

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Originally retrieved from and based on http://www.xbox-linux.org/wiki/SMBus_Controller by ''Michael Steil'' (original version: 15/26 June 2002)

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by ''Michael Steil'' (original version: 15/26 June 2002)

All non-PC components of the Xbox console are connected through an I²C/SMbus interface. I²C/SMBus is a slow low-cost serial bus with each device having a unique 7-bit ID. (Wikipedia has informative articles about [https://web.archive.org/web/20100617015507/http://en.wikipedia.org/wiki/I2c I²C] and [https://web.archive.org/web/20100617015507/http://en.wikipedia.org/wiki/SMBus SMBus], you might want to check them out.)

All non-PC components of the Xbox console are connected through an I²C/SMbus interface. I²C/SMBus is a slow low-cost serial bus with each device having a unique 7-bit ID. (Wikipedia has informative articles about [https://web.archive.org/web/20100617015507/http://en.wikipedia.org/wiki/I2c I²C] and [https://web.archive.org/web/20100617015507/http://en.wikipedia.org/wiki/SMBus SMBus], you might want to check them out.)

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There are only two operations of an SMBus controller: write and read. Writing means that an 8 bit command code and an 8 or 16 bit operand are sent to an SMBus device. Reading means that an 8 bit command code is sent to the device and an 8 or 16 bit answer is expected.

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There are only two operations of an SMBus controller: write and read. Writing means that an 8 bit command code and an 8/16/32 bit operand are sent to an SMBus device. Reading means that an 8 bit command code is sent to the device and an 8/16/32 bit answer is expected.

The controller for the SMBus interface in the Xbox is a PCI device with the DevID 01B4 and it is built into MPCX southbridge. It supports bus arbitration and the Xbox kernel will retry transactions if a collision occurs. This means it is safe to use a second SMBus master (like a USB-SMBus adapter) while the Xbox is running ''as long as the second master also supports arbitration''. Adapters based on the Silicon Labs CP2112 or Microchip MCP2221 chips will work, for example.

The controller for the SMBus interface in the Xbox is a PCI device with the DevID 01B4 and it is built into MPCX southbridge. It supports bus arbitration and the Xbox kernel will retry transactions if a collision occurs. This means it is safe to use a second SMBus master (like a USB-SMBus adapter) while the Xbox is running ''as long as the second master also supports arbitration''. Adapters based on the Silicon Labs CP2112 or Microchip MCP2221 chips will work, for example.

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SMBus