TC65 Hardware Interface Description
Strictly confidential / Draft
s
TC65_HD_V00.521 Page 49 of 99 24.05.2005
3.11 USB Interface
TC65 supports a USB 2.0 Full Speed (12Mbit/s) device interface. 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 [6] 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.
To properly connect the module’s USB interface to the host a USB 2.0 compatible connector
is required. Furthermore, the USB modem driver delivered with TC65 must be installed as
described below.
The USB host is responsible for supplying, across the VUSB_IN line, power to the module’s
USB interface, but not to other TC65 interfaces. This is because TC65 is designed as a self-
powered device compliant with the “Universal Serial Bus Specification Revision 2.0”
1
.
MCU
USB
Transceiver
lin.
Regulator
PSU
Baseband controller
GSM module
Host
22Ohms
22Ohms
1.5kOhms
USB_DP
USB_DN
VUSB_IN
5V3V
D+
D-
VBUS
GND
80 pole board-to-board connector
Figure 14: USB circuit
1
The specification is ready for download on http://www.usb.org/developers/docs/
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