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USB MultiSwitch
TM
Hub
Datasheet
SMSC USB2524 23 Revision 1.91 (08-22-07)
DATASHEET
7.1.4.7 Register 06h: CONFIG_BYTE_1 (Reset = 0x00)
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
SELF_PWR pin is used to determine if the hub is operating from self
or bus power.
6 Reserved Reserved, always = ‘0’.
5 HS_DISABLE High Speed Disable: Disables the capability to attach as either a High/Full-
speed device, and forces attachment as Full-speed only i.e. (no High-Speed
support).
0 = High-/Full-Speed.
1 = Full-Speed-Only (High-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) {Note: The host may force Single-TT mode only}. When using the internal
default option, the MTT_EN pin enables/disables MTT support.
0 = single TT for all ports.
1 = one TT per port (multiple TT’s supported)
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).
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!)
0 PORT_PWR Port Power Switching: Enables power switching on all ports simultaneously
(ganged), or port power is individually switched on and off on a port- by-port
basis (individual). The ability to support power enabling on a port or ganged
basis is hardware implementation dependent.
0 = Ganged switching (all ports together)
1 = Individual port-by-port switching.