User's Manual

AC65/AC75 Hardware Interface Description

Confidential / Preliminary

AC65/AC75_hd_v00.372 Page 58 of 118 2006-08-03

3.12 USB Interface

AC65/AC75 supports a USB 2.0 Full Speed (12Mbit/s) device interface. It can be operated

on a USB 2.0 Full Speed or High Speed root hub (a PC host), but not on a generic USB 2.0

High Speed hub which translates High Speed (480 Mbit/s/) to Full Speed (12 Mbit/s).

The USB port has different functions depending on whether or not Java is running. Under

Java, the lines may be used for debugging purposes (see [16] for further detail). If Java is not

used, the USB interface is available as a command and data interface and for downloading

firmware.

The USB I/O-pins are capable of driving the signal at min 3.0V. They are 5V I/O compliant.

The USB host is responsible for supplying, across the VUSB_IN line, power to the module’s

USB interface, but not to other AC65/AC75 interfaces. This is because AC65/AC75 is

designed as a self-powered device compliant with the “Universal Serial Bus Specification

Revision 2.0”

MCU

USB

Transceiver

lin.

Regulator

PSU

Baseband controller

GSM module

Host

22Ohms

1.5kOhms

USB_DP

USB_DN

VUSB_IN

5V3.2V

D+

D-

VBUS

GND

80 pole board-to-board connector

Figure 18: USB circuit

To properly connect the module’s USB interface to the host a USB 2.0 compatible connector

is required. For more information on how to install a USB modem driver and on how to

integrate USB into AC65/AC75 applications see [11].

The specification is ready for download on http://www.usb.org/developers/docs/