Buttons and knobs

Buttons, knobs and an LED make the box work without the web page: volume, next, pause. Everything a button does is an action, the same actions that cards use (Cards).

Buttons on the pins (GPIO)

Buttons, rotary encoders (knobs) and a status LED on the pins of the Pi are the plugin Buttons, encoders, LED (gpio_controls). Switch it on under Settings → Plugins; the web page installs what it needs. Then set up the buttons there. You choose pins from the list of free pins, and Settings → Hardware shows which pin is used by what.

In the settings file it looks like this:

plugins:
  gpio_controls:
    buttons:
      next:
        pin: GPIO5                  # as the board names it; on a Pi also 5 or pin29
        on_press: {action: player.next}
      play:
        pin: GPIO6
        on_press: {action: player.toggle}
        on_hold: {action: hardware.shutdown}
        hold_time: 3                # seconds for on_hold
        pull_up: true               # the button connects the pin to ground
    rotary_encoders:
      volume:
        pin_a: GPIO17
        pin_b: GPIO27
        clockwise: {action: volume.change_volume, args: {step: 2}}
        counter_clockwise: {action: volume.change_volume, args: {step: -2}}
    status_led: GPIO25              # on while Lauschkiste runs

With on_hold, a short press runs on_press when the button is released and a long press runs only on_hold. A button whose pin is already used by something else is skipped (the log says so), the others keep working.

USB buttons, joysticks and keyboards

Any device that Linux sees as an input device can trigger actions: USB buttons, a joystick, a keyboard, even a game controller. Map the keys in the settings:

input:
  devices:
    joystick:
      device_name: DragonRise Inc.   Generic   USB
      exact: false                 # false: the name only has to be contained
      keys:
        BTN_TRIGGER: {action: player.toggle}
        BTN_THUMB: {action: player.next}
        BTN_TOP: {action: volume.change_volume, args: {step: 5}}

To find the name of the device and its keys, run python -m evdev.evtest on the box and press the buttons. Names are KEY_* or BTN_*; numbers work too. The user running Lauschkiste needs to be in the group input. A device that is plugged in later is found by itself.

The buttons of Bluetooth headphones work through input.media_keys: true, see Sound and Bluetooth.