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Auto On HDMI Port

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M Hightower edited this page Jan 5, 2019 · 4 revisions

Bash script to turn on the HDMI Port on a Raspberry Pi

Issues and Assumptions:

  • When a display is not plugged into the HDMI port at boot time, the video defaults to the analog connector.
  • While the HDMI Hot Plug option works, unless you set all the geometry values, you do not get a good match for physical screen size to virtual size as well as a good font size.
  • If you use the hdmi_force_hotplug=1 option in the /boot/config.txt file and you setup good geometry values in the /boot/config.txt file. Then, when you use a different monitor, everything is broken again.
  • It is assumed, that the Monitor connected to the HDMI works well when it is already connected at the time your Raspberry Pi is powered up and boots. The port properties present at this time, are the ones that are captured for later use.

Do's and Don'ts

  • When using this script do not set thehdmi_force_hotplug=1 option in the /boot/config.txt file.
  • For each monitor you may use with the Raspberry Pi, connect it and boot once. This gives the script the opportunity to capture/cache working geometry settings for each monitor.

Implementation

Uses tvservice and fbset to make the HDMI port ready for use. Relies on a USB keyboard or mouse being plugged in, to trigger a udev rules entry, that will launch the script to turn on and set up the HDMI port. The script runs for 30 seconds, waiting for a monitor to be plugged into the HDMI port, before timing out.

To install

cd /usr/local/bin
sudo wget https://github.com/mhightower83/misc-bash/raw/master/auto-on-hdmi-port
sudo chmod +x auto-on-hdmi-port
sudo auto-on-hdmi-port --install

Script Usage Options

Usage for "/usr/home/bin/auto-on-hdmi-port":

  sudo auto-on-hdmi-port --install

    Installs systemd service to run the command "auto-on-hdmi-port
    --update-cache" at boot time. Installs udev rules to run the
    command "auto-on-hdmi-port --power-on" when a USB HID device is
    connected. eg. Plugging in a USB keyboard or USB mouse.


  sudo auto-on-hdmi-port --uninstall

    Undo "auto-on-hdmi-port --install".



  Next two options are for reference.

  auto-on-hdmi-port --power-on [how long to wait in seconds, optional]

    This command is used to start the script, to monitor for a display
    connected to the HDMI port. When the display is connected, it runs
    the programs to set up the HDMI port. This is the command that is
    launched via the udev rules RUN command. (must run from root)


  auto-on-hdmi-port --update-cache

    This command is issued at boot time by the systemd service
    auto-on-hdmi-port.service.  This script option will capture and record
    the geometry of a working display with its device_name value. This
    information is stored in the file "/usr/local/etc/displayCache". (must
    run from root)


  auto-on-hdmi-port --help

    Prints this message.


  auto-on-hdmi-port --help-dev

    Prints help on some deprecated options that were used during development.

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