Specifications

PC/II+p Board Technical Reference Manual 70

7.27 USB Ports

PC/II+p contains an integrated USB controller within the ALI M1543C south bridge, that provides one root

hub with two USB ports based on OpenHCI 1.0a Specification. The 4 differential data signals (2 for each

port) are provided on the Mass I/O Connector, J904.

Serial transfers are supported as follows:

FS – 12 Mbits/Second

LS – 1.5 Mbits/Second

The USB state machine is driven by a 48 MHz crystal oscillator to generate all USB signals. The controller

also contains a PCI interface and master and target host control functions.

The USB register level programming interface is characterized as:

Base class – 0Ch – serial bus controller

SubClass – 03h – universal serial bus

Programming Interface – 10h – OpenHCI

The interface consists of two pairs of differential signals, U1-D+ and U1-D- for port 0, and U2-D+ and U2-D-

for port 1. In addition, +5V power and Ground are provided on the USB port connectors normally located on

a transition board (for example, on the Megatel Qtb/Dxp-sm board). The USB VCC +5V pin is normally

protected by an off-board .5A resettable fuse.

Please contact Megatel for an up-to-date list of drivers supporting USB peripherals.

7.27.1 USB Interface Pinout

Table 37 Signals – J904 – USB Ports 0 & 1 Interface

PIN NAME PIN# SIGNAL NAME SIGNAL DESCRIPTION

U1-D+

d19 Differential Data (Pos) Positive Differential Data

U1-D-

c19 Differential Data (Neg) Negative Differential Data

U2-D+

b19 Differential Data (Pos) Positive Differential Data

U2-D-

a19 Differential Data (Neg) Negative Differential Data