110118-0001A
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The processor can configure Serial 2 as an IrDA port. IrDA should be used in conjunction with
the IrDAOn signal (J3), which enables the IrDA transmitter. IrDA transceivers can be panel
mounted or placed on a personality board.
Serial 2 is configured for 3.3 V logic level operation only. It connects directly to the processor and
should be treated electrically as digital I/Os. See section 6.3.9 for electrical specifications.
4.5.2
USB
The BitsyXb includes signals for USB 1.1 Host and Client ports. Both the USB Host
(downstream) port and the USB Function ("Client" or upstream) port are managed by the PXA270
processor. The BitsyXb can be configured as a self-powered hub, with one Host and one Client
port.
To create a USB connection, you must wire a standard USB socket as described in the following
sections. For each type of connector, pin numbering is as follows:
Pin
USB signal
1
USB_PWR
2
USB -
3
USB +
4
GND
USB Host
The BitsyXb USB Host port allows you to connect one USB device to the BitsyXb. USB mouse
and keyboard are the most common client devices, but you can connect any USB function device
that has USB drivers installed on the BitsyXb.
Use a Type A connector for the host signals on J10 pins 14 and 16 (section 3.3.8). The mating
face of such a socket is shown at left. The USB standard also permits directly wiring the USB
signals to the target USB device (e.g. USB mouse). To connect more than one USB client device
to the BitsyXb, use a USB hub.
The USB protocol allows client devices to negotiate the power they need from 100 mA to 500 mA
in 100 mA increments. The BitsyXb supplies 5 V power through the USB_PWR pin. Make sure
to account for power used through USB in your BitsyXb power budget (section 5.4.1). It is
recommended that you use a power switch.
The BitsyXb supports two power control signals on J10. USB_PWR_SENSE is an input that
detects over-current conditions. USB_PWR_CTRL is an output that controls power to the USB
port. See the BitsyXb CF Personality Board (Eurotech p/n 640111-8000) for an example of how
to use these signals. Electrical specifications are in section 6.3.9.
USB Function (Client)
The BitsyXb includes a USB Function (or "Client") port. This interface allows the BitsyXb to
appear as a client device to USB Host devices such as desktop and laptop computers.
The USB Function signals are available on connector J3, pins 29 and 30. Connect these signals to
a USB Function Type B socket (mating face shown at left). The USB standard also permits
directly wiring the USB signals to the host or to a host connector.
Connecting the USB Function Port
This section describes how to connect the signals to create a fully-functioning USB Function port.
See the Eurotech Bitsy Personality Board reference designs (section 2.1.2) for examples of how to
put these instructions into practice.
