LPC47M14X datasheet(171/205 Pages) SMSC

171 / 205 page

SMSC DS – LPC47M14X

Page 171

Rev. 03/19/2001

Table 76 – HubControl_1 Register Definition

HubControl_1

RESET=0x00

INDEX=0xF7

HUB CONTROL REGISTER 1

BIT

NAME

R/W

DESCRIPTION

NHubReset

R/W

NHubReset – When this bit is asserted (0), the hub controller is in a reset

state. The hub will not respond to any enumeration or device requests.

When this bit is de-asserted (1), the hub controller is ready to receive

packets from the Root Host Controller. Each Port will then be enabled via a

control packet from the Host

Strp1

R/W

Strp0

R/W

Strap Select – The two bits define the number of USB Down Stream Ports

that will be enabled. The Default value which is sampled during VT POR, is

defined by the Input Pins nStrp1 and nStrp0. The state of the input pins are

the logical invert of the associated Strp1 and Strp0 bits. The number of

ports enabled is defined in the following table:

Strp1 Strp0

Ports Enabled

Reserved – This selection is for future use

PD1+/-,PD2+/-

PD1+/-,PD2+/-,PD3+/-

PD1+/-,PD2+/-,PD3+/-,PD4+/- (Default)

Note: For backward compatibility with existing older revision

devices, the default for Strp1 and Strp0 is 00. This implies that the

input pins nStrp1 and nStrp0, are required to not be connected.

See Note 1:

4:1

Reserved

Reserved – Reads return 0

Ganged

PWR

R/W

Ganged Power Sense Enable – When this bit is set (1), the Power Control

block of the USB HUB device will internally OR the Power OK sense pins

(nUSBOC[3:0]) and Power Enable (nPWREN[3:0]) pins. This will allow the

system designer the ability to reduce implementation costs by reducing the

external current hardware. In this mode, since only one Sense and Enable

PIN is required, the unused input pins must be tied to VDD (1) and the

unused output pins may be left unconnected.

See Note 1:

Note 1: When the specified USB Down Stream Ports are disabled via the Strp0/Strp1 bit or nStrp1/nStrp0 Pins, the

associated Over-current sense pins (nUSBOC[x]) and Power Enable (nPWREN[x]) pins are also disabled. The USB

Down Stream Port nUSBOC[x] input pin can be a NC (No Connect) pin or tied High (1) and the Power Enable

(nPWREN[x]) pin will be forced low (0).

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