Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 2.2 (02-17-12) 30 SMSC USB251xB/xBi
DATASHEET
5.1.7 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 all externally available
downstream ports (max 100 mA) must consume no more than 500 mA of
upstream VBUS current. The current consumption is system dependent and
must not violate the
USB 2.0 Specification [1].
When configured as a self-powered device, < 1 mA of upstream VBUS
current is consumed and all ports are available. Each port is capable of
sourcing 500 mA of current.
This field is set over either the SMBus or I
2
C EEPROM interface options.
0 : bus-powered operation
1 : self-powered operation
If dynamic power switching is enabled (Section 5.1.8), this bit is ignored and
LOCAL_PWR is used to determine if the hub is operating from self or bus
power.
6 rsvd
5 HS_DISABLE Hi-Speed Disable: disables the capability to attach as either a hi- or full-
speed device, forcing full-speed attachment 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.
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 : multi-TT (one TT per port)
3 EOP_DISABLE EOP Disable: disables End Of Packet (EOP) generation at End Of Frame
Time #1 (EOF1) when in full-speed mode.
During full-speed operation only, the hub can send EOP when no
downstream traffic is detected at EOF1. See the
USB 2.0 Specification,
Section 11.3.1
for details.
0 : EOP generation is normal
1 : EOP generation is disabled
2:1 CURRENT_SNS Over-Current Sense: selects current sensing on all ports (ganged); a port-
by-port basis (individual); or none (for bus-powered hubs only). The ability to
support current sensing on a ganged or port-by-port basis is hardware
implementation dependent.
00 : ganged sensing
01 : individual sensing
1x : over-current sensing not supported (use with bus-powered
configurations)