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Power management daemon for Raspberry Pi based tablet.


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Power, Display, and UI Management Daemon for DIY Raspberry Pi Tablet

PiTabDaemon is a background process for monitoring and controlling the state of a Raspberry Pi based tablet, as described here ( It performs the following functions, once per millisecond unless otherwise noted:

  • checks for a shutdown signal from the power switch and initiates a proper shutdown.

  • monitors the three buttons and performs the corresponding actions:

    • bring keyboard (short press) or dashboard (long press) to front
    • increase brightness by 1/8 (short press) or to maximum (long press)
    • toggle foreground application between normal and maximized (short press) or full screen (long press)
  • monitors commands from the dashboard (every 5 seconds):

    • enable/disable screen dimming on idle when on battery power
    • enable/disable USB and Ethernet ports
    • enable/disable Wi-Fi and Bluetooth
  • power monitoring:

    • status of PowerBoost 1000C charging and charge-completed indicators
    • battery voltage
    • estimate of energy remaining
    • information is written to a tiny RAM disk for display by dashboard
  • monitors X11 idle time (at varying intervals depending on need):

    • dims display to half of selected brightness after 2 minutes of inactivity
    • turns off backlight completely after 5 minutes
  • monitors PowerBoost 1000C LBO and performs an immediate shutdown if triggered.

The daemon makes use of the following open source libraries and utilities:

  • bcm2835 - low level GPIO library used to monitor buttons, voltage, etc.
  • libxss and xscreensaver - allows the daemon to monitor user idle time.
  • wmctrl - command line utility used by the daemon to resize windows.

PiTabDaemon is intended to be used in conjunction with PiTabDashboard (


Power management daemon for Raspberry Pi based tablet.







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