SMSC LAN9512 - Manual (Page 28)

USB Hub with Integrated 10/100 Ethernet Controller
Datasheet
Revision 1.0 (04-20-09) 28 SMSC LAN9512
DATASHEET
Table 3.4 Config Data Byte 1 Register (CFG1) Format
BITS DESCRIPTION DEFAULT
7 Self or Bus Power (SELF_BUS_PWR)
Selects between Self or Bus-Powered operation.
0 = Bus-Powered
1 = Self-Powered
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 USB2.0 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.
1b
6 RESERVED 0b
5 High Speed Disable (HS_DISABLE)
Disables the capability to attach as either a High/Full-Speed device, and
forces attachment as Full-Speed only (no High-Speed support).
0 = High-/Full-Speed
1 = Full-Speed-Only (High-Speed disabled)
0b
4 Multiple TT Enable (MTT_ENABLE)
Enables one transaction translator per port operation.
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) {Note: The host may force Single-TT mode only}.
0 = Single TT for all ports.
1 = One TT per port (multiple TT's supported)
1b
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 = An EOP is generated at the EOF1 point if no traffic is detected.
1 = EOP generation at EOF1 is disabled (note: this is normal USB
operation).
Note: This is a rarely used feature in the PC environment, existing drivers
may not have been thoroughly debugged with this feature enabled.
It is included because it is a permitted feature in Chapter 11 of the
USB specification.
1b