Digilent I/O Explorer Reference Manual - Page 4
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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 a discussion of the options available for powering the VS
bus.
Jumper JP3 can be used to connect the I/O Explorer unregulated power bus VU to the servo power bus, VS. When
no shorting block is installed on JP3, the VU and VS busses are separate. When a shorting block is on JP3, the two
busses are joined and the VU bus can be powered in any of the previously indicated ways, or from connector J10.
The I/O Explorer can provide power to any peripheral modules attached to the Pmod ports and to I2C devices
powered from the I2C daisy chain connector, J12.
Each Pmod port provides power pins that can be powered from either unregulated voltage, VU, or regulated
voltage, 3V3, by setting the voltage jumper block to the desired position. Note that when the operating voltage
select jumper JP7 is in the 5V0 position, the USB or external power supply voltage will be supplied to the Pmod
ports regardless of the position of the voltage select jumpers at the connectors.
The I2C power connectors provides 3.3V when the main board operating voltage (selected by JP7) is 3.3V, or the
external supply voltage when JP7 is in the 5V0 position.
The 3.3V supply provided to the Pmod and I2C connectors is provided by the onboard voltage regulator. This
regulator is capable of providing a maximum of 500mA of current. The circuitry on the I/O Explorer will consume
less than 100mA in normal operation. The remaining current is available to provide power to attached Pmod and
I2C devices. The regulator is on the bottom of the board, near the power connectors, and will get warm when the
amount of current being used is close to its limit.
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USB Operation
When operating using the normal factory firmware, the I/O Explorer functions as a USB 2.0 compliant full speed
device. Normal operation requires installation of the Digilent Adept Runtime software system, and it is accessible
to applications software developed using the Digilent Adept Software Developer's Kit (SDK). The Digilent Adept
Software Developer's Kit and the Digilent Adept Runtime system is available for download from the Digilent web
site: www.digilentinc.com
By replacing the factory firmware with end-user developed firmware, the I/O Explorer can function as a user
defined USB device.
The primary microcontroller (AT90USB646) contains a USB 2.0 Compliant, Full Speed Device controller. Refer to
the Atmel data sheet for the AT90USB646 and the USB 2.0 Specification for information on developing USB device
firmware.
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On-board I/O Devices
The I/O Explorer provides the following I/O Devices on the board:
8 Slide switches
4 Push button switches
4 Position DIP switch
16 Discrete LEDs
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