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LEGO MINDSTORMS EV3

Input / Output Ports

.. kernel-doc:: ev3/ev3_ports_core.c
    :doc: userspace

Input Ports

.. kernel-doc:: ev3/ev3_ports_in.c
    :doc: userspace


.. lego-port:: ev3_input_port_mode_info

Output Ports

.. kernel-doc:: ev3/ev3_ports_out.c
    :doc: userspace


.. lego-port:: ev3_output_port_mode_info

Buttons

The EV3 buttons use the standard Linux input subsystem. You can find the event device node at /dev/input/by-path/platform-gpio-keys.0-event. The buttons are mapped to Linux key codes as shown in the table below.

.. flat-table:: Button map
    :widths: 1 1
    :header-rows: 1

    * - Button
      - Linux key code (value)

    * - Back
      - ``KEY_BACKSPACE`` (14)

    * - Center
      - ``KEY_ENTER`` (28)

    * - Up
      - ``KEY_UP`` (103)

    * - Left
      - ``KEY_ENTER`` (105)

    * - Right
      - ``KEY_ENTER`` (106)

    * - Down
      - ``KEY_DOWN`` (108)

LEDs

The EV3 brick status LEDs used the standard Linux LEDs subsystem. You can find the LED devices at /sys/class/leds/. There are two bi-color LEDs. The color for each LED is controlled separately, so there is a green and red device node for each LED. Turning both of these on at the same time will make the LED appear orange(ish).

The LEDs are controlled by a PWM signal, so you can vary the brightness between 0 and max_brightness.

Display

The EV3 display uses the standard Linux frame buffer subsystem (fbdev). The display memory can be directly accessed by reading and writing or memory mapping /dev/fb0. Display attributes such as width, height and row stride can be read using FBIOGET_VSCREENINFO and FBIOGET_FSCREENINFO ioctls.

Note

You must make sure that you control the active virtual console before drawing on the display, otherwise other programs could be writing to the display at the same time, causing unexpected results.

Sound

.. kernel-doc:: ev3/legoev3_sound.c
    :doc: userspace

Battery

  • This driver is used to get information about the EV3 battery.
  • It uses the power_supply subsystem.
  • It registers a sysfs device node at /sys/class/power_supply/lego-ev3-battery/.
.. flat-table:: Sysfs Attributes
    :widths: 1 3

    * - ``current_now``
      - Returns the battery current in microamps.
    * - ``scope``
      - Always returns ``System``.
    * - ``technology``
      - Returns ``Unknown`` or ``Li-ion`` depending on if the rechargeable
        battery is present. If the technology is ``Unknown``, you can write
        ``NiMH`` to this attribute if you are using rechargeable NiMH batteries.
    * - ``type``
      - Always returns ``Battery``.
    * - ``voltage_max_design``
      - Returns the nominal "full" battery voltage. The value returned
        depends on ``technology``.
    * - ``voltage_min_design``
      - Returns the nominal "empty" battery voltage. The value returned
        depends on ``technology``.
    * - ``voltage_now``
      - Returns the battery voltage in microvolts.