SMSC USB2512Ai - Manual (Page 16)

Industrial Temperature Rated USB 2.0 Hi-Speed 2-Port Hub Controller
Datasheet
Revision 1.97 (08-11-08) 16 SMSC USB2512Ai
DATASHEET
4.2.1.7 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 2mA of upstream bus
power) or Bus-Powered (limited to a 100mA 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 100mA 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 100mA per externally available
downstream port) must consume no more than 500mA 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, <1mA of upstream VBUS
current is consumed and all ports are available, with each port being capable
of sourcing 500mA 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
Note: 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 Reserved Reserved
3 EOP_DISABLE EOP Disable: Disables EOP generation of 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. Note: generation of an EOP at the EOF1
point may prevent a Host controller (operating in FS mode) from placing the
USB bus in suspend.
0 = EOP generation is normal
1 = EOP generation is disabled
2:1 CURRENT_SNS Over-Current Sense: Selects current sensing on a port-by-port basis, all
ports ganged, or none (only for bus-powered hubs). The ability to support
current sensing on a port or ganged basis is hardware implementation
dependent.
00 = Ganged sensing (all ports together)
01 = Individual port-by-port
1x = Over-current sensing not supported (must only be used with Bus-
Powered configurations!)