8.1. Led and Buzzer API

Access Server's LEDs and buzzer can be accessed through the /dev/led device. You can check the status of the LEDs and the buzzer with the cat /dev/led command and set LEDs or the buzzer with the echo abcde > /dev/led command. An upper case letter means that the LED or buzzer is ON, a lower case letter means that the LED or buzzer is OFF. Letter "a" is the buzzer, letters "b".."e" are LEDs 1..4.

Example:

      [root@wrap /] echo abCDe > /dev/led
    

8.2. GPIO API

The Digital I/O pins of Access Server can be controlled write-only by using the /dev/io device in the same way as the /dev/led device for LEDs and buzzer described above.

The letter-to-I/O mapping of the 16 pins is as follows, when looking at the connector:

      hgfedcba
      Xijklmno
    

X is the ground pin (and cannot be set).

o is the voltage sense pin (user can use any voltage from 3.3V to 5.0V).

The I/O must first be enabled by using the echo Z > /dev/io command. After that, pins can be driven up by echoing the corresponding upper case letter (A-N) or down by echoing a lower case letter (a-n) to the /dev/io device.

Example:

      [root@wrap /] echo ZaBcD > /dev/io