Smsc LAN9512 User Manual download pdf (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.

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)

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)

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.

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