Power button and battery

Both pages below describe hardware that is not yet tested on real hardware in this project.

Power button (Pimoroni OnOff SHIM)

The OnOff SHIM switches the Pi on with a button press, shuts it down cleanly with the next press and then cuts the power. In Lauschkiste it is the plugin Power button with the preset Pimoroni OnOff SHIM (button on GPIO17, power off on GPIO4). No Pimoroni script is needed.

1. Answer yes to “Is a power button attached” in lauschctl setup (or switch on the plugin under Settings → Plugins and restart).
2. lauschctl setup raspi, then restart. This adds dtoverlay=gpio-poweroff,gpiopin=4,active_low=1 to the boot configuration, which cuts the power once the system has halted.

A press shuts Lauschkiste down like a shutdown card: playback stops, positions are saved, the shutdown sound plays, then the Pi halts and the SHIM switches it off. Other power buttons work the same way with the hardware Own pins.

Wiring the SHIM separately

The SHIM has a 12-pin header that needs soldering. To save pins for other things you can wire it separately:

Board pin name	Board pin	Raspberry Pi pin	Name
3.3V	1	1, 17	3V3
5V	2	2	5V
5V	4	4	5V
GND	6	6, 9, 20, 25	ground
GPLCLK0	7	7	GPIO4
GPIO17	11	11	GPIO17

More at pinout.xyz.

Battery monitor

The plugin Battery reads a battery sensor on I²C, shows the charge under Settings → Status, runs an action when the battery gets low (for example a warning sound) and shuts the box down cleanly before it is empty. Answer the question about a battery monitor in lauschctl setup; the Pi device plugin switches I²C on (lauschctl setup raspi, then restart).

Driver	Sensor	Charge from
max17048	MAX17048 fuel gauge (Adafruit, SparkFun LiPo boards), address 0x36	the gauge
ina219	INA219 current and voltage sensor	the voltage (empty_voltage to full_voltage)
simulator	none, discharges slowly	the voltage

plugins:
  battery:
    driver: max17048
    i2c_bus: 1                 # SDA is GPIO2, SCL GPIO3
    warning_voltage: 3300      # millivolts: runs warning_action once
    shutdown_voltage: 3000     # millivolts: shuts the box down
    warning_action: {action: jingle.play, args: {sound: /path/to/low-battery.wav}}