VIPER
Detailed hardware description
© 2004 Arcom Issue H
42
USB interface
There are two USB interfaces on the VIPER. These interfaces have been designed to
support the Open Host Controller Interface (OpenHCI).
There are four signal lines associated with each USB channel:
•
VBUS
•
DPOS
•
DNEG
•
GND
Their arrangement is summarized in the following illustration:
A USB power control switch controls the power and protects against short-circuit
conditions. See the section
, for details of control.
If the USB voltage is short-circuited, or more than 500mA is drawn from either supply,
the switch turns off the power supply and automatically protects the device and board.
The VBUS power supply is derived from the VIPER +5V supply.
If you require details for the USB bus, or would like to determine whether particular
peripherals are available, see
A factory fit option changes USB port 1 from a host interface to a device using
the PXA255 USB controller. Please contact Arcom for more details. Contact
details are provided in
1
2
3
4
1
2
3
4
1
2
10 (SHIELD)
(SHIELD) 9
VBUS 1
DNEG 1
DPOS 1
GND
VBUS 2
DNEG 2
DPOS 2
GND
USB Connector 1
USB Connector 2
PL7