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USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 1.0 (3-11-09) 38 SMSC USB251x
DATASHEET
8.2.1.7 Register 06h: CONFIG_BYTE_1
BIT
NUMBER BIT NAME DESCRIPTION
7 SELF_BUS_PWR Self or Bus Power: Selects between Self- and Bus-Powered operation.
The hub is either self-powered (draws less than 2 mA of upstream bus
power) or bus-powered (limited to a 100 mA maximum of upstream power
prior to being configured by the host controller).
When configured as a bus-powered device, the SMSC hub consumes less
than 100 mA of current prior to being configured. After configuration, the bus-
powered SMSC hub (along with all associated hub circuitry, any embedded
devices if part of a compound device, and 100 mA per externally available
downstream port) must consume no more than 500 mA of upstream VBUS
current. The current consumption is system dependent, and the OEM must
ensure that the USB 2.0 specifications are not violated.
When configured as a self-powered device, <1 mA of upstream VBUS
current is consumed and all ports are available, with each port being capable
of sourcing 500 mA of current.
This field is set by the OEM using either the SMBus or EEPROM interface
options.
Please see the description under dynamic power for the self-/bus- power
functionality when dynamic power switching is enabled.
'0' = Bus-powered operation
’1’ = Self-powered operation
If dynamic power switching is enabled, this bit is ignored and the
LOCAL_PWR pin is used to determine if the hub is operating from self or
bus power.
6 Reserved Reserved
5 HS_DISABLE Hi-speed Disable: Disables the capability to attach as either a Hi-/Full-Speed
device, and forces attachment as Full-Speed only (i.e. no Hi-Speed support).
'0' = Hi-/Full-speed
‘1’ = Full-speed-Only (Hi-speed disabled!)
4 MTT_ENABLE Multi-TT enable: Enables one transaction translator per port operation.
(Not available on the USB2512A/12Ai.)
Selects between a mode where only one transaction translator is available
for all ports (Single-TT), or each port gets a dedicated transaction translator
(Multi-TT).
'0' = Single TT for all ports
‘1’ = One TT per port (when multiple TT's are supported)
3 EOP_DISABLE EOP Disable: Disables EOP generation at EOF1 when in Full-Speed mode.
During FS operation only, this permits the hub to send EOP if no
downstream traffic is detected at EOF1. See Section 11.3.1 of the USB 2.0
specification for additional details.
'0' = EOP generation is normal
‘1’ = EOP generation is disabled