Letux Kernel


Table of Content

How to control Devices from user space (command line)


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


see Video


see Sound

Headset out / AUX in

The audio amplifier is controlled by (state=0: AUX IN, state=1: AUX OUT)

echo $state >/sys/devices/virtual/gpio/gpio55/value

If enabled, you can't use the AUX IN


The vibra motor can be used like a force-feedback joystick through /dev/input/rumble or as a speaker membrane for playing "sound" through aplay (see Sound for an example).

Here is a Python script for using /dev/input/rumble:


Note: you must switch the ALSA mixer control "Vibra" to 'Local vibrator'. See Sound.


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

echo $state >/sys/devices/virtual/gpio/gpio57/value

Note: this is no longer available in 3.7 and later kernels.

Touch Screen

see Video


see GPS


see Camera

AUX and Power button

Button Status

The AUX button status can be read through

cat /sys/devices/virtual/gpio/gpio7/value  # 0=AUX pressed

The AUX button is available through a TPS GPIO button driver as an input key event. The power button is available through the TPS driver as an input key event.


Both buttons are configured as keyboard events through /dev/input/aux and /dev/input/power.

The codes are KEY_POWER and KEY_PHONE.


see LEDs


Depending on the exact version of the board there may be I2C devices (besides the touch screen controller).

You should install http://packages.debian.org/de/lenny/i2c-tools resp. http://www.lm-sensors.org/wiki/I2CTools


There should be the following commands

  • i2cdetect
  • i2cdump
  • i2cget
  • i2cset

ADCs of the TPS65950

are available through /dev/twl4030-madc and the madc driver. See e.g. http://www.jumpnowtek.com/index.php?option=com_content&view=article&id=79&Itemid=91

  • ADC0: BATID (default: 0V)
  • ADC1: BATTEMP (default: 1.5V)
  • ADC2: ADC2IN (default: 0V)
  • ADC7: MICSENSE (no headset / short / headset)

Many values are also mapped to /sys/devices/platform/twl4030_madc_hwmon/*