How to control Devices from user space (command line)

Introduction

This page lists the most important devices and drivers that are specific to this board. And how they can be accessed from user space.

For the Angstrom Image, we have predefined symbolic links in /dev/platform

Touch Screen

is mapped to

/dev/input/touchscreen

pen down status can be read through

cat /sys/devices/virtual/gpio/gpio157/value

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.

choose from user space by ???

DVI

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

S-Video

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

Backlight

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

echo $state /sys/devices/virtual/gpio/gpio145/value

GPS

power (state=0: off, state=1: on) - you may have to switch on/off/on to reset the GPS chip

echo $state /sys/devices/virtual/gpio/gpio156/value

device file (use 9600 baud)

cat /dev/ttyS1

if the external antenna is active can be determined through

cat /sys/devices/virtual/gpio/gpio138/value  # 1=ext. ant.

AUX and Power button

button status can be read through

cat /sys/devices/virtual/gpio/gpio136/value  # 0=AUX pressed
cat /sys/devices/virtual/gpio/gpio137/value  # 0=POWER pressed

LEDs are switched through

    echo $state /sys/devices/virtual/gpio/gpio70/value  # AUX - red
    echo $state /sys/devices/virtual/gpio/gpio71/value  # AUX - green
    echo $state /sys/devices/virtual/gpio/gpio78/value  # POWER - red
    echo $state /sys/devices/virtual/gpio/gpio79/value  # POWER - green