Specifications

Chapter 3 Hardware

LittleBoard 735 Reference Manual 29

USB Interfaces

The I/O Hub (82801GBM) provides the USB solution for both legacy UHCI controller and EHCI controller

(USB 2.0) support. The I/O Hub (Southbridge) contains port-routing logic that determines which controller

(UHCI or EHCI) handles the USB data signals. The J44 header provides two of the six USB ports: USB0

and USB1. The J14 header provides USB2 and USB3, and the J39 header provides USB4 and USB5.

USB 2.0 Support

The I/O Hub (Southbridge) contains an Enhanced Host Controller Interface (EHCI) compliant host

controller, which supports up to six high-speed USB 2.0 Specification compliant root ports. The higher

speed USB 2.0 specification allows data transfers up to 480 Mbps using the same pins as the six full-speed/

low-speed USB UHCI ports. The I/O Hub (Southbridge) port-routing logic determines which of the

controllers (UHCI or the EHCI) processes the USB signals.The USB 2.0 features implemented in the USB

ports include the following:

• One EHCI host controller for all six USB ports

• Supports USB V2.0 Specification

Legacy USB Support

The I/O Hub (Southbridge) supports three USB Universal Host Controller Interfaces (UHCI) and each Host

Controller includes a root hub with two separate USB ports each, for a total of six USB ports. The USB

Legacy features implemented in the USB ports include the following:

• Three root hubs for six USB ports

• Support for USB v1.1 and UHCI v1.1 with integrated physical layer transceivers

• Improved arbitration latency for UHCI controllers

• UHCI controllers support Analog Front End (AFE) embedded cell instead of USB I/O buffers to allow

for USB high-speed signaling rates

• Three shared over-current fuses, located on the board, are used on all six USB ports

USB0 and USB1

Table 3-10 lists the USB0 and USB1 pin signals which use 10 pins, 2 rows, odd/even sequence (1, 2) with

0.079" (2mm) pitch.

CAUTION ADLINK does not recommend connecting a USB boot device to the

LittleBoard 735 through an external hub. Instead, connect the USB boot

device directly to the LittleBoard 735.

Table 3-10. USB 0 & 1 Interface Pin Signals (J44)

Pin # Signal Description

USBPWR0 +5 volts power, USB 0

USBPWR1 +5 volts power, USB 1

3 USB0- USB 0 Data Negative

4 USB1- USB 1 Data Negative

5 USB0+ USB 0 Data Positive

6 USB1+ USB 1 Data Positive

USB GND0 USB 0 Ground

USB GND1 USB 1 Ground