Digital Signage/Displays

You can turn a RaspberryPi/Single Board Compter (SBC) into "digital signage" using open source tools and a few scripts.

Prerequisites

You will need a few prerequisites before this will work:

• A TV/Monitor (preferably mounted) to display content
• A RaspberryPi or similar SBC (I've also used LibreComputer LePotato SBC running Armbian)
• A webserver to serve up the content you want to show (preferably external to the SBC)

Basic Display

This is the most basic configuration you can use to turn a RaspberryPi/SBC into a digital sign/display that serves up a web page when started.

Software

You will need to install the following packages:

• openbox
• xdg (may already be installed, check for /etc/xdg/autostart)
• unclutter
• xinit
• xdotool
• chromium browser
• chromium driver

Setup

Do the following to setup the device to display the URL of your choice.

/etc/xdg/openbox/autostart

Replace the contents of this file with the following:

# Disable any form of screen saver / screen blanking / power management
xset s off
xset s noblank
xset -dpms

# Allow quitting the X server with CTRL-ATL-Backspace
setxkbmap -option terminate:ctrl_alt_bksp

# Start Chromium in kiosk mode
sed -i 's/"exited_cleanly":false/"exited_cleanly":true/' ~/.config/chromium/'Local State'
sed -i 's/"exited_cleanly":false/"exited_cleanly":true/; s/"exit_type":"[^"]\+"/"exit_type":"Normal"/' ~/.config/chromium/Default/Preferences

#comment this line below once chromium auto-refresh plugin is configured (requires menus hidden by code below), see also /home/pi/.proflie

#Change the '''''<url to display>''''' in the line below to the URL that you want shown
URL='<url to display>'

#First launch of Chromium to install extensions, adjust screen size, etc.   Command out after first launch.
chromium $URL

#Uncomment one of the three options below once chromium auto-refresh plugin is configured

#Show URL page with 1.25x zoom
#chromium --disable-infobars --kiosk --noerrdialogs --enable-features=OverlayScrollbar --disable-restore-session-state --force-device-scale-factor=1.40 $URL

#Show URL page with (1.45x zoom):
#chromium --disable-infobars --kiosk --noerrdialogs --enable-features=OverlayScrollbar --disable-restore-session-state --force-device-scale-factor=1.45 $URL

#Show URL page 1.5x zoom
#chromium --disable-infobars --kiosk --noerrdialogs --enable-features=OverlayScrollbar --disable-restore-session-state --force-device-scale-factor=1.50 $URL

Add kiosk user

We will add a user called kiosk that will autologin and display the web page we defined in the script above.

Note: You can set the password to anything you want here since it will be ignored by the autologin configuration.

adduser kiosk

Turn on autologin

1. Create the required directory with:

mkdir /etc/systemd/system/getty@tty1.service.d

2. Create the autologin.conf file in the newly created /etc/systemd/system/getty@tty1.service.d directory and add the contents below.

Note: Change kiosk below to the username that will be used for autologin if you are using something different (root is not recommended)

[Service]
ExecStart=
ExecStart=-/sbin/agetty -o '-p -f -- \\u' --noclear --autologin kiosk %I $TERM

[Install]
After=network-online.target
Wants=network-online.target
WantedBy=multi-user.target

Ensure this is enabled with:

systemctl status getty@tty1

● getty@tty1.service - Getty on tty1
     Loaded: loaded (/lib/systemd/system/getty@.service; enabled; preset: enabled)
     Active: active (running) since Wed 2025-02-19 17:07:45 PST; 29min ago
       Docs: man:agetty(8)
             man:systemd-getty-generator(8)
             https://0pointer.de/blog/projects/serial-console.html
   Main PID: 776 (agetty)
      Tasks: 1 (limit: 2306)
     Memory: 212.0K
        CPU: 12ms
     CGroup: /system.slice/system-getty.slice/getty@tty1.service
             └─776 /sbin/agetty -o "-p -- \\u" --noclear - linux

Run the following command if the service isn't enabled:

systemctl enable getty@tty1

Set kiosk user .profile

Change /home/kiosk/.profile to the contents below:

# ~/.profile: executed by the command interpreter for login shells.
# This file is not read by bash(1), if ~/.bash_profile or ~/.bash_login
# exists.
# see /usr/share/doc/bash/examples/startup-files for examples.
# the files are located in the bash-doc package.

# the default umask is set in /etc/profile; for setting the umask
# for ssh logins, install and configure the libpam-umask package.
#umask 022

# if running bash
if [ -n "$BASH_VERSION" ]; then
    # include .bashrc if it exists
    if [ -f "$HOME/.bashrc" ]; then
        . "$HOME/.bashrc"
    fi
fi

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/.local/bin" ] ; then
    PATH="$HOME/.local/bin:$PATH"
fi

#
# Wait up to 30 seconds for network to come online before continuing for IP address
count=0
mcount=30

while [ "$(hostname -I)" = "" ]; do
  echo -e "\e[1A\e[KNo network: $(date)"
  sleep 1
  let "count+=1"
  [[ ${count} -gt ${mcount} ]] && exit 1
done

echo "* Network is online"

sleep 3

#Uncomment this line once chromium auto-refresh plugin is configured or if no additional configuration is needed.
#[[ -z $DISPLAY && $XDG_VTNR -eq 1 ]] && startx -- -nocursor

First Time Startup

Now restart the SBC and it should automatically login as your kiosk user and stop at the command prompt.

Additional Configuration

If you need to do additional configuration for Chromium (install an autorefresh or other extension(s), change screen size, etc). then start the browser with:

startx

This will start the Chromium browser displaying the URL you specified and showing the address bar and menu where you can make the necessary adjustments. Once finished, press CTRL+ALT+BACKSPACE to exit back to the command line.

Finalize Configuration

1. Edit /etc/xdg/openbox/autostart, commenting out the first instance of chromium and uncomment one of the lines that launches chromium in kiosk mode.
2. Edit /home/kiosk/.profile and uncomment the last line of the file.
3. Reboot.

The SBC will boot up and launch Chromium to show the web page you specified.

Display with Remote Management

This builds off the Display 1 setup with some additional features:

• VNC using NOVNC. This allows remote control of the display via a web browser.
• Loading message and time displayed. This uses OSDSH for the overlay.

Software

Install the following additional packages:

• osdsh
• novnc
• python3-websockify
• python3-numpy
• tigervnc-scraping-server
• tigervnc-standalone-server
• tightvncpasswd
• tightvncserver
• tigervnc-tools

Setup

Make the following changes

/etc/xdg/openbox/autostart

Replace the contents of this file with the following:

Note: change <URL TO VISIT> to webserver URL you want to display.

#
# These things are run when an Openbox X Session is started.
# You may place a similar script in $HOME/.config/openbox/autostart
# to run user-specific things.
#

# If you want to use GNOME config tools...
#
#if test -x /usr/lib/aarch64-linux-gnu/gnome-settings-daemon >/dev/null; then
#  /usr/lib/aarch64-linux-gnu/gnome-settings-daemon &
#elif which gnome-settings-daemon >/dev/null 2>&1; then
#  gnome-settings-daemon &
#fi

# If you want to use XFCE config tools...
#
#xfce-mcs-manager &

#Start x0vncserver and serve up VNC on port localhost:5900
/usr/bin/x0vncserver -passwordfile /home/kiosk/.vnc/passwd -display :0

# If you want to use XFCE config tools...
#
#xfce-mcs-manager &
# Disable any form of screen saver / screen blanking / power management
xset s off
xset s noblank
xset -dpms

# Allow quitting the X server with CTRL-ATL-Backspace
setxkbmap -option terminate:ctrl_alt_bksp

#Start websockify to proxy novnc to port 6080 using self-signed SSL cert and vnc on localhost:5900
/usr/bin/websockify -D --web=/usr/share/novnc/ --cert=/home/kiosk/novnc.pem --ssl-only 6080 localhost:5900

#Start OSDSH
/usr/bin/osdsh -p 1 -a 1 -n 20 -c blue

chromium-browser --disable-infobars --kiosk --noerrdialogs --enable-features=OverlayScrollbar --disable-restore-session-state --force-device-scale-factor=1.25 '<URL TO VISIT>' &

#Display to give a 15 second delay for initial page loading/rendering
/usr/bin/osdctl -e "dset(f,helvetica)"
/usr/bin/osdctl -e "dset(C,dark red)"
dload="DISPLAY LOADING - ONE MOMENT"
for LSET in 10 20 30 40 50 60 70 80 90
do
   /usr/bin/osdctl -b "$dload,$LSET"
   sleep 2
done
/usr/bin/osdctl -b "LOADING DONE,100"
sleep 5

#Set default color to cyan
/usr/bin/osdctl -e "dset(C,cyan)"

#Set clock to bottom of screen
/usr/bin/osdctl -e "sclk(b)"

#Set clock to center of screen
/usr/bin/osdctl -e "sclk(c)"

#set clock color to blue
/usr/bin/osdctl -e "sclk(C,blue)"

#Set clock font to courier new
/usr/bin/osdctl -e "sclk(f,courier new)"

#Set clock format
/usr/bin/osdctl -e "clkf(%a %b %d %Y - %l : %M : %S %p)"

sleep 1

#Run clock indefinitely
/usr/bin/osdctl -c 1

#Loop to pause then press F5 in chromium for page refresh
while true; do
    sleep 90
    osdctl -s "Screen will refresh in 5 seconds"
    sleep 5
    xdotool key F5
done

Generate SSL certificate

• Navigate to the /home/kiosk user directory
• Run the following command to generate a self-signed SSL certificate with a 10 year life span:

openssl req -x509 -nodes -newkey rsa:3072 -keyout novnc.pem -out novnc.pem -days 3650

Generate VNC Password File

Run the following command to create the vnc password file (make note of this for later):

vncpasswd

Firewall

Edit (or create) the /etc/rc.local file and add/replace the contents with the following:

#!/bin/bash
#Firewall rules to block VNC to all but localhost for NOVNC access
iptables -F log-and-drop
iptables -X log-and-drop
iptables -N log-and-drop

# Specific chain used for logging packets before blocking them
iptables -A log-and-drop -j LOG --log-prefix "[IPTables] Drop "
iptables -A log-and-drop -j DROP

iptables -A INPUT -p tcp --dport 5900 -j ACCEPT --src localhost
iptables -A INPUT -p udp --dport 5900 -j ACCEPT --src localhost
iptables -A INPUT -p tcp --dport 5900 -j log-and-drop
iptables -A INPUT -p udp --dport 5900 -j log-and-drop

• Enable systemd service to run rc.local at start

systemctl enable rc-local

• Make script executable

chmod a+x /etc/rc.local

First Time Startup

Restart the SBC to make sure it will boot up and start Chromium.

Remote Access via NOVNC

You can manage the device by pointing a web browser at https://<device IP>:6080

• When prompted accept the invalid certificate
• Login to NOVNC using the password you created using vncpasswd

Miscellaneous

Sometimes things happen and the display will "get stuck" or lose internet connectivity. When this happens you have a few options:

1. Setup a nightly reboot event via crontab or systemd timers
2. Setup a watchdog to look for lost network connectivity and restart the system