Aaeon SBC-770 User Manual page 39

You can use an LED to indicate when the CPU card is on. Pin1 of
CN1 supplies the LED's power, and Pin3 is the ground.
You can use a switch (or a lock) to disable the keyboard so the PC
will not respond to any input. This is useful if you do not want
anyone to change or stop a running program. Connect the switch
between Pin 4 and 5 of CN1.
Pin
1
2
3
4
5
You can connect an LED to CN2 to indicate when the HDD is
active.
Pin
1
2
28 SBC-770 User Manual
Function
LED power (Vcc)
N.C.
GND
Keyboard lock
GND
Function
HD-LED+
HD-LED-