Digilent 410-174P - Manual (Page 4)

USB I/O Explorer Reference Manual
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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
connectors and to I2C devices powered from
the I2C daisy chain connector, J12.
Each Pmod connector 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 connectors 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.
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
•
2 Rotary encoders with integral
push buttons
• Speaker/Buzzer
When operating the I/O Explorer using the
factory firmware, these devices are accessible
using the DGIO API set as described in the
DGIO Programmer’s Reference Manual
contained in the Digilent Adept SDK. Refer to
the section Digilent Adept Port Descriptions
below for details on the ports used for access
to the on-board I/O devices.
When operating the I/O Explorer with user
defined firmware, these devices are accessible
from the primary microcontroller via a private
I2C bus described below. All of these on-board
I/O devices are connected to the secondary
microcontroller and custom firmware written for
the secondary microcontroller can access them
directly.