Digilent 410-174P - Manual (Page 17)

USB I/O Explorer Reference Manual
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J6 Secondary Microcontroller (ATmega165P) Debug Connector
This connector allows use of an Atmel JTAG ICE mkII or AVR Dragon to perform in-
system programming and debug of code running in the secondary microcontroller. Note:
the fuses must be set to enable the JTAG interface to allow in-system debug.
J7-J9 Ground Posts
These provide a GND connection for use when using external test equipment, such as
an oscilloscope, to probe signals on the board.
J10 Servo Bus Power
This screw terminal connector is used to provide power to the servo power bus VS
when the servo power bus is being powered separately from the board main power bus.
J11 Internal I2C Bus
This connector provides access to the two signals for the internal I2C bus used to
communicate between the two microcontrollers and the MCP4728 DAC.
J12 TWI BUS Daisy Chain Connector
This connector is used to connect external devices to the DTWI bus.
J13-J15 External Power Supply Connectors
These three connectors are wired in parallel and are used to connect an external power
source to the board when operating the I/O Explorer as a self-powered USB device, or
when not using USB.
JP1 Primary Microcontroller (AT90USB646) In-System-Programming Connector
This connector is used to access the primary microcontroller for in-system-
programming. It is intended for use with a Digilent programming cable, although other
Atmel AVR in-system programmers will work with a suitable cable adapter.
JP2 Secondary Microcontroller (ATmega165P) In-System-Programming Connector
This connector is used to access the secondary microcontroller for in-system-
programming. It is intended for use with a Digilent programming cable, although other
Atmel AVR in-system programmers will work with a suitable cable adapter.
JP3 Servo Bus Power Select
Insert a shorting block on this jumper to join the servo power bus, VS, to the main board
power bus, VU. With the shorting block installed, the VS bus is powered from the main
board power supply. With the shorting block removed, the VS bus is powered via
connector J10.
JP4 & JP5 TWI Bus Pull-up Enable
These jumpers are used to enable/disable the pull-ups on the DTWI bus. Installing the
shorting blocks enables the pull-ups, removing the shorting blocks disables them.
The pull-ups on the I/O Explorer are implemented using current mirrors, rather than
simple pull-up resistors. This provides improved reliability when driving longer busses.
JP6 Main Power Source Select
This jumper is used to select the main power source for the board. Place a shorting
block in the VUSB position to power the board from the USB connector. Place a
shorting block in the VEXT position to power the board from one of the external power
connectors J13, J14, or J15. An external power supply should provide a regulated 5V.
An external voltage greater than 5.5V should never be applied or damage to the board
will occur.
J7 Operating Voltage Select
This jumper is used to select the operating voltage for the board. Place a shorting block
in the 3V3 position to operate the board from the internal 3.3V regulator. Place a
shorting block in the 5V0 position to operate the board from the input supply (either
USB or externally applied 5V) voltage.