AMD 4.4.5 Switch User Manual

AMD Confidential
User Manual November 21
, 2008
Chapter 7: Device Configuration 105
7.18 SMB Hub Device
The SMB hub device is used to connect one SMBus to any of four SMBus branches. The
device is programmed via read-byte and write-byte commands on the SMBus where the
7-bit address field is 0x18.
The SMB hub device models the combination of two physical devices manufactured by
Philips Semiconductors: the PCA9516 5-channel I
C hub, and the PCA9556 Octal
SMBus and I
C registered interface. In the simulator‟s device model the two devices are
configurable via GPIO x enables segment x, as shown in Figure 7-30.
The SMB hub has five SMBus interfaces. SMB0 can be connected within the SMB hub
to any of the four other SMBuses (SMB[1..3]). Typically, SMB0 is connected to a
SMBus connection on a Southbridge device, and the other SMBus ports are connected to
other devices in the system.
Initialization and Reset State
When first initialized or reset the SMB hub registers are set to their default state. The
internal registers and their default states are described in the PCA9556 data sheet.
Contents of a BSD
The current state of all internal registers and any internal state variables are saved in the
Configuration Options
The SMB Hub device allows you to enable up to eight GPIO segments (GPIO0 GPIO7)
to connect SMB devices to SMB hub device, as shown in Figure 7-30.