Kontron KTT20-pITX - Manual (Page 46)

KTD-S0045-D Page 42 AndroidTM BSP
KTT20/pITX Software Guide
10.3 Display Density
In the system file ' /system/build.prop ' the entry ' ro.sf.lcd_density ' can change the density on both graphic
units (DVI ® and LCD panel) for a better look. The lower the value (e.g. 180, 160 or 130), the higher density
and smaller font your screen will have but it is possible that the navigation bar disappears.
10.4 GPIOs, Temperatures, Backlight and Bootcounter
The Android TM BSP does not support the KEAPI interface. Some special functions are realized with the sysfs
in-memory filesystem which allows the kernel to export information to a user space. All following examples
can be executed with the serial remote connection (e.g. with TeraTerm on a desktop PC).
10.4.1 GPIOs
For correlation between GPIO numbers and physical pins refer the 'KTT20/pITX Users Guide' chapter 'Digi-
tal I/O Interface'.
’ Please use the export function before you access a GPIO pin.
echo >/sys/class/gpio/export
Example for GPIO16:
echo 16 >/sys/class/gpio/export
’ Check the GPIO pin direction:
cat /sys/class/gpio/gpio /direction
Example for GPIO16:
cat /sys/class/gpio/gpio16/direction
’ Set the GPIO pin direction:
echo in >/sys/class/gpio/gpio /direction set direction to input
echo out >/sys/class/gpio/gpio /direction set direction to output
Example for GPIO16:
echo in >/sys/class/gpio/gpio16/direction
echo out >/sys/class/gpio/gpio16/direction
’ Get an input value:
cat /sys/class/gpio/gpio /value
Example for GPIO16:
cat /sys/class/gpio/gpio16/value
’ Set an output value:
echo -n 0 >/sys/class/gpio/gpio /value set output to low level
echo -n 1 >/sys/class/gpio/gpio /value set output to high level
Example for GPIO16:
echo -n 0 >/sys/class/gpio/gpio16/value
echo -n 1 >/sys/class/gpio/gpio16/value
’ Release the GPIO pin:
echo >/sys/class/gpio/unexport
Example for GPIO16:
echo 16 >/sys/class/gpio/unexport