TUSB2036

2/3-PORT HUB FOR THE UNIVERSAL SERIAL BUS

WITH OPTIONAL SERIAL EEPROM INTERFACE

SLLS372 – MARCH 2000

3

POST OFFICE BOX 655303

description (continued)

The hub silicon can accurately reflect the system port configuration by the NP3 and NPINT1-0 pins. When NP3

is low, the hub is configured as a 3-port hub; when it is high, the hub is configured as a 2-port hub. The NPINT1-0

pins tell the hub silicon how many ports have permanently attached devices, according to Table 1.

Table 1. System Port Configuration

NPINT1-0

PORT AVAILABILITY

HUB DESCRIPTOR

DEVICE REMOVABLE FIELD (7–0)

00

All ports are available through external USB connectors

00000000

01

Port 1 has a permanently attached device; ports 2 and 3 are externally available

00000010

10

Ports 1 and 2 have permanently attached devices; port 3 is externally available

00000110

11

All ports have permanently attached devices

NP3 high: 00000110

NP3 low: 00001110

NPINT1-0

COMPOUND DEVICE OR NOT

HUB DESCRIPTOR WITH HUB

CHARACTERISTICS FIELD BIT 2

00

Hub is not part of a compound device

0

01, 10, 11

Hub is part of a compound device

1