Raspberry Pi Public Display - broadcast messages and information for students, lecturers, teachers, staff and visitors

Version 14.3.21

Start -- Bug in Raspberry Pi OS 32 bit buster and impress (14.4.21):

Impress slide show stop working after some minutes.
https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=248757

Raspberry stretch and OS 64 bit are correctly working!

My workaround is to use the program okular
https://okular.kde.org/

Therefor I save my Impress or PowerPoint presentation as PDF.

In Okular I can start the pdf as "presentation".

In the settings of okular I give 15 sec from one slide to the next and loop the presentation.

A second workaround is to keep the impress presentation and run a script file with
DISPLAY=:0 xdotool key space

This is like pressing the keyboard the space key.

Therefor install xdotool.

The script is permanently running.

refresh_key_space.sh:

#!/bin/bash
# sleep and then press space
# for Impress when slide freeze
while true
do
DISPLAY=:0 xdotool key space
sleep 5m
done

Add this line to /etc/xdg/lxsession/LXDE-pi/autostart
/home/pi/Desktop/refresh_key_space.sh

End --- Bug in Raspberry Pi OS 32 bit buster and impress

Raspberry Pi Public Display

The monitor is set up in the main entrance of our institute.
The upcoming lectures and events are displayed on the monitor.

I use a Raspberry Pi linked with hdmi-caple to the monitor. The Raspberry Pi is connected by cable to the Ethernet.

I use LibreOffice Impress to show the slides.
With SSH and WinSCP I copy new "presentation.odp" files to the desktop and start the presentation in Impress.

For this I have two batch files that end and restart the presentation.

Raspberry Pi 3 Model B
Display Monitor Nec Public Display V423, 42 Zoll

https://www.linuxmuster.net/wiki/anwenderwiki:infoboard:raspberry-pi

https://www.andysblog.de/raspberry-pi-2-model-b-fuer-praesentationen-verwenden

Install Raspberry Pi OS

Use at least 8 GB SD Card. I used a 32 GB microSDHC Card from ScanDisk.
Connect the card with SD-Card Adapter to a Ubuntu 16.04 PC.
Download the latest Raspberry Pi OS Software for the Raspberry Pi.
Use the .zip-file.
https://www.raspberrypi.org/downloads/
To transfer the Raspberry Pi OS to the SD card I used Etcher
How to install Raspberry Pi OS:
https://www.raspberrypi.org/documentation/installation/installing-images/README.md
Etcher
https://etcher.io/
Simply dopple click to the downloaded file in Ubuntu, Etcher will start.
Raspberry Pi OS is now on the SD card.

Configure Raspberry Pi OS for the public display

Raspberry Pi OS has already installed LibreOffice. I used Impress to show the presentation on the public display.
If not you can easily install LibreOffice.
sudo apt-get install libreoffice

But first I had to configure the Raspberry Pi OS.

1. Static IP instead of DHCP

To connect to the Raspberry remote I use SSH with static IP.

Configure the interfaces:
sudo nano /etc/network/interfaces
Type in the following text:
auto eth0
iface eth0 inet static
address x.x.x.x
netmask 255.255.254.0
gateway x.x.x.x
dns.nameservers 134.2.200.1 134.2.200.2

Restart the network with
sudo /etc/init.d/networking restart

2. Change Password

To change the password go to
sudo raspi-config
1 Change User Password

3. SSH

To activate SSH simply go to
sudo raspi-config
5 Interfacing Options
SSH
...enable?
Yes

4. Hostname

To change the hostname go to
sudo raspi-config
2 Network Options
N1 Hostname

5. Change Autostart

The raspberry should restart without login screen and show the LibreOffice Impress presentation.

sudo nano /etc/xdg/lxsession/LXDE-pi/autostart

(In older Raspbian Versions I used the autostart in the pi profile
sudo nano ~/.config/lxsession/LXDE-pi/autostart
)

Make to a comment the following text:
#@xscreensaver -no-splash
#This stopps the screensaver.
@xset s off
@xset -dpms

#To avoid the shutdown of the display
@xset s noblank

#Delete the lock to open the openoffice.
sudo rm -f /home/pi/Desktop/.~lock*

#Open the file presentation.odp in the folder Desktop
soffice --show --norestore /home/pi/Desktop/presentation.odp

6. Manually start and stop presentation with SSH

To start and stop the presentation by SSH, I had to executable files presentation_stop and presentation_start.
Create a file presentation_stop with the following text:
#!/bin/bash
sudo pkill soffice.bin

Create a file presentation_start with the following text:
#!/bin/bash
if test -e /home/pi/Desktop/.~lock.praesentation.odp#
then
sudo rm /home/pi/Desktop/.~lock.praesentation.odp#
fi
DISPLAY=:0 libreoffice --nologo --norestore --show /home/pi/Desktop/praesentati$

Make both file executable with chmod +x.

7. Fix the resolution to the Public Display

Normally Raspberry Pi should recognize the resolution of the monitor.
In my case not. Therefor I fix the resolution in the config.txt file.
sudo nano /boot/config.txt
Type in the following text:
hdmi_group=2
hdmi_mode=82
hdmi_force_hotplug=1

This force the DMT modus
1920x1080/60Hz (1080p)
and hotplug.

8. Config LibreOffice Presentation

To make the presentation endless and automatically show the next slide configure the presentation.odp with the LiberOffice Impress program.

9. Firewall

I use UFW to allow acces only in my subnet.
https://raspberrypi.stackexchange.com/questions/14381/only-use-raspberry-pi-in-local-network/14477

Install UFW

sudo apt-get install ufw

deny all incoming connetions

sudo ufw default deny

allow the local network connections (subnet 134.2.54.0 - 134.2.55.254) sudo ufw allow from 134.2.54.0/23

enable the ufw

sudo ufw enable

check the rules

sudo ufw status verbose

Delete rules
https://pimylifeup.com/configuring-ufw/#ufwdeleterule

sudo ufw status numbered

sudo ufw delete <mumber of the rule>

ZMBP Zeugs

Freitag, 29. Dezember 2017