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I/O Explorer™ USB Reference Manual

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.

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.

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

Other product and company names mentioned may be trademarks of their respective owners.

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