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Chapter 3
Utility Interfaces
The Utility interfaces consists of three connectors that provide the standard interface signals for the
following devices:
•
Utility 1 (J15)
♦
Keyboard
♦
External battery connection
♦
Reset Switch
♦
Speaker
• Utility 2 (J13)
♦
PS/2 Mouse
♦
Infrared (IrDA) signals
♦
SMBus signals
♦
USB signals for USB ports 1 and 2
♦
Power button signal
• Utility 3 (J14)
♦
USB signals for USB ports 3 (USB0) and 4 (and USB1)
Utility 1 Interface (J15)
The Utility 1 (J15) interface uses an 18-pin connector and provides the various interface signals to an
external I/O board with external connections for the respective connectors, such as, keyboard, speaker,
etc. Table 3-17 gives the pin-outs and interface signals for Utility 1 interface and has 16 pins, 2 rows,
odd/even, (1, 2) with 0.100" pin spacing.
•
Keyboard
• Battery
• Reset Switch
• Speaker
• External voltages (-5V In, -12V In, +3.3V Out to Power On LED)
Keyboard Interface
The signal lines for a PS/2 keyboard are provided through the Utility 1 interface (J15), which is also
fully PC/AT compatible.
External Battery
An external battery input connection is provided through a Utility 1 interface (J15) for the Real Time
Clock's operation in the event the on-board battery is not used.
Reset Switch
The signal lines for a reset switch (hard or soft) are provided through the Utility 1 interface (J15).
NOTE
To perform the equivalent of a power-on reset, the reset button
must be pressed and held for a minimum of three seconds.
LittleBoard 800
Reference Manual
Hardware
45
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