Digilent 410-174P - Manual (Page 3)

USB I/O Explorer Reference Manual
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JTAG-ICE mk II or the Atmel AVR Dragon for
in-system debug. In-system programming is
normally accomplished using a Digilent
programming cable, either the Digilent JTAG-
USB Programming Cable, or the Digilent
JTAG-USB Full Speed Module. The use of an
Atmel ISP In System Programmer is also
supported with the use of a suitable flying-lead
cable (e.g. Digilent 6 Pin MTE Cable) to
convert from the Digilent 1x6 programming
connector convention to the Atmel 2x3
connector convention.
For additional information useful in developing
custom firmware for the board, the complete
schematic is available on the Digilent web site.
Power Supply
The I/O Explorer may be used either as a USB
bus powered device or as a self powered
device. Jumper JP6 is used to select between
these two options. Install a shorting block in
the VUSB position for USB bus power. Install a
shorting block in the VEXT position for self
power.
Power switch, SW10, is used to turn board
power on or off. Ensure that the power switch
is in the ON position to operate the board.
When operating as a bus powered device, care
should be taken in powering devices external
to the I/O Explorer. The 5V USB bus power
supply is available at the Pmod connectors and
other points on the board. Care should be
taken not to exceed the 500mA current limit
that USB bus powered devices are allowed to
consume. Care should particularly be taken not
to short the USB 5V supply to ground or
external voltage supplies as this could result in
damage to the USB hub or PC motherboard to
which the I/O Explorer is connected.
When operating as a self powered device,
there are three power supply connectors on
the I/O Explorer for connecting the external
power supply: J13, J14, and J15. These three
connectors are wired in parallel and only one
of the three should be used at a time.
The barrel connector, J13, will normally be
used for desktop applications as a self
powered device. J13 is the connector used by
the AC supply adapter optionally available from
Digilent, or other sources. J13 is a 2.5mm x
5.5mm coaxial connector wired with the center
terminal as the positive voltage.
J14 is a screw terminal connector for use with
higher current battery packs, bench supplies or
other power sources where use of a hard wired
power supply is desirable.
J15 is a two-pin male header that provides
easy battery or battery-pack connection.
Digilent has both two-cell and four-cell AA
battery holders with two pin connectors
available for connection to J14.
The main operating voltage of the I/O Explorer
can be selected between one of two voltages.
Jumper JP7 is used to select between these
two voltages. With JP7 in the 3V3 position, the
main board power bus is powered from the
output of the 3.3V main power supply regulator
on the board. When JP7 is in the 5V0 position,
the main power supply regulator is bypassed,
and the main board power bus is powered
directly from the applied supply voltage. When
operating as a USB bus powered device, this
will be the USB bus 5.0V power supply. When
operating as a self powered device, this will be
the voltage of the external supply. In this case,
the external supply should not exceed 5.5V or
damage to the board will result.
The main power supply regulator on the I/O
Explorer is rated for external power from 3.6 to
9 volts DC. Using a voltage outside this range
could damage the board and connected
devices.
The I/O Explorer has a second screw terminal
connector, J10 that supplies power to the
servo power bus, VS, to power the RC hobby
servo connectors. This allows servos to be
powered from a separate power supply than
the one powering the electronics on the I/O
Explorer. This can be useful when using
servos that require large amounts of power.
See the section on Servo Connectors below for