How to control the DSS outputs (LCD, TV-Out, DVI) and touch screen

LCD and touch screen

LCD

can be selected by adding "omapdss.def_disp=lcd" to the boot args. This is done by "setenv defaultdisplay lcd" in our boot.scr.

To disable/enable (power down/up) the LCD (state=0: off, state=1: on)

echo "$state" >/sys/devices/omapdss/display2/enabled

For more information about switching the DSS2 system, please refer to http://processors.wiki.ti.com/index.php/DSS2_SYSFS_Examples

Touch Screen

is mapped to

/dev/input/touchscreen

pen down status can be read asynchronously through

cat /sys/devices/virtual/gpio/gpio160/value

Video out (can't be used in parallel to headset microphone input)

can be selected by adding "omapdss.def_disp=venc" to the boot args

To disable/enable (power down/up) the LCD (state=0: off, state=1: on) in the DSS system:

echo "$state" >/sys/devices/omapdss/display1/enabled

The video out amplifier is automatically controlled by enabling display1, but it can be controlled independently through (state=0: off, state=1: on)

echo $state >/sys/devices/virtual/gpio/gpio23/value

NOTES: * while gpio23 is "1", you can't use the headset microphone * there is no automatic detection of a video display connection * the 75 Ohm output is short circuit protected

DVI (on Beagleboard only!)

can be selected by adding "omapdss.def_disp=dvi" to the boot args

power (state=0: off, state=1: on)

echo $state >/sys/devices/virtual/gpio/gpio170/value

This is only available if the kernel is configured for the BeagleBoard.

Switch LCD to TV-out

echo 0 > /sys/devices/platform/omapdss/display2/enabled
echo 0 > /sys/devices/platform/omapdss/overlay0/enabled
echo "" > /sys/devices/platform/omapdss/overlay0/manager
fbset -fb /dev/fb0 -xres 720 -yres 574 -vxres 720 -vyres 574
echo "tv" > /sys/devices/platform/omapdss/overlay0/manager
echo 1 > /sys/devices/platform/omapdss/display1/enabled
echo 1 > /sys/devices/platform/omapdss/overlay0/enabled

For NTSC:

 fbset -fb /dev/fb0 -xres 720 -yres 482 -vxres 720 -vyres 482

Switch TV-Out to LCD

echo 0 > /sys/devices/platform/omapdss/display1/enabled
echo 0 > /sys/devices/platform/omapdss/overlay0/enabled
echo "" > /sys/devices/platform/omapdss/overlay0/manager
fbset -fb /dev/fb0 -xres 480 -yres 640 -vxres 480 -vyres 640
echo "lcd" > /sys/devices/platform/omapdss/overlay0/manager
echo 1 > /sys/devices/platform/omapdss/display2/enabled
echo 1 > /sys/devices/platform/omapdss/overlay0/enabled