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ZEUS Technical Manual Detailed hardware description
© 2007 Eurotech Ltd Issue D 51
USB
There are two USB host interfaces on the ZEUS. These comply with the Universal
Serial Bus Specification Rev. 1.1, supporting data transfer at full-speed (12Mbit/s) and
low-speed (1.5Mbit/s).
There are four signal lines associated with each USB channel: VBUS, DATA+, DATA-,
GND. The USB host ports are connected to a dual USB connector, type A (J8).
A USB power control switch controls the power and protects against short-circuit
conditions. If the USB voltage is short-circuited, or more than 500mA is drawn from
either supply, the switch turns the power supply off and automatically protects the
device and board. The VBUS power supply is derived from the ZEUS +5V supply. To
switch the VBUS1 and VBUS2 power on, use the PXA270 GPIO89 and GPIO22
respectively (set them to logic ‘1’).
USB port 2 can be configured as a client port internally within the PXA270 USB
controller, and is connected to 5-pin header J10.
For details of connector pinouts, see the sections J8 – USB connector
, page 81, and
J10 – USB client header
, page 82.
More information about the USB bus and the availability of particular USB peripherals
can be found at www.usb.org
.
Host port 2 on J8 and client port on J10 can only be used one at a time.
DO NOT connect both devices at the same time.