PSC Video Wall

The controller rack key is in the cubby to your right hanging on a hook and is hanging on a key in that cubby:

Power on

To power up the rack and the monitors, just hit the "System Power" button on the upper right corner of the rack. That's it. If everything is working ok then what happens is that first the RaspberryPi boots up, then it automatically powers up the monitors, then waits a few seconds and runs a Firefox web browser in full screen mode, then starts up the controller software.

When the controller software is running, the touchscreen should see this:

Power down To power down, first hit the "Shutdown" button on the touchscreen, then wait until the monitors are off and the touchscreen is dark. Then power down using the "System Power" button on the upper right corner of the rack. That's it. Then lock the system up. If the monitors don't go off, call for help (Drew Baden, Jordan Goodman, Steve Rolston are good candidates).

This is an executable python script that lives in /home/physics/wall/wall.py. It is run when the desktop starts up, and you do this by adding a file called

    ~/.config/autostart/wall.desktop

    [Desktop Entry]
    Type=Application
    Name=Wall Controller
    Comment=Start wall Python app on login
    Exec=/home/physics/wall/wall.py
    Terminal=false
    X-GNOME-Autostart-enabled=true

There's also a text window where you can type a URL, and a "Navigate" button. Type in a URL and hit Navigate and it will send a message to the Firefox browser running on the monitors to go to that address.

Typing "Exit" will exit the program. If you do this by mistake, you will see an icon on the desktop called "Video Wall Controller", just double touch that to get it running again.

At startup, the system runs Firefox in the HDMI window. It does this by having another startup file called

    ~/.config/autostart/firefox-kiosk.desktop

    [Desktop Entry]
    Type=Application
    Name=Firefox Kiosk
    Exec=/home/physics/scripts/start-firefox-hdmi.sh
    X-GNOME-Autostart-enabled=true

    ~/scripts/start-firefox-hdmi.sh

    #!/usr/bash

    # Give the session time to come up
    sleep 5

    # Force Firefox to run on the HDMI monitor under Wayland
    export MOZ_ENABLE_WAYLAND=1
    export MOZ_WL_OUTPUT=HDMI-A-1

    # Launch firefox in kiosk mode with a real URL
    /usr/bin/firefox --kiosk "https://www.physics.umd.edu"

We use the Brightlink 4k 3x3 Video Wall Controller:

The rear has all of the relevant inputs: the bottom row of 9 outputs and the top row has inputs from a computer.

The bottom outputs are labeled "HDMI Out1" ... up to "HDMI Out9". The video wall has 9 monitors in a 3x3 matrix, so let's label them Top-Mid-Bot and L-M-R for rows and columns. Each monitor on the wall has an Extron rx unit, driven by the Extron tx unit in 0204, and each Extron tx has an HDMI input that comes from the Brightlink, and these are labeled A1, A2, A3, and etc B and C. Here's the mapping from the A1..3,B1..3,C1..3 to the video wall matrix:

Brightlink mapping of what HDMI cables (labeled A1, A2...) go into what Brighlink output is here:

The Brightlink allows you to setup from either the front panel by pushing the white buttons, or using the remote, or using the web interface. We use the latter.

To use it, drag a laptop into 0204 and get a USB->Ethernet adapter and plug it into the blue cat6 cable that is connected into the "IP" input on the rear of the Brightlink. I used an Apple MacBook Pro, and I found that to connect to the Brightlink, I had to first turn Wifi off. Then open up the network settings and you should see the "USB 10/100/1000 LAB" interface and it should say Connected. Click on it and go into the TCP/IP setup and configure it for Manual IP, then use 192.168.1.8 and subnet mask 255.255.255.0. The Router is 192.168.1.1. Save that configuration, open up a browser, and browse to the Brightlink which is at 192.168.1.168. Login as admin and put in the password (Drew Baden, Jordan Goodman, Anne Suplee, and Steve Rolston know it). If that works, you should see this screen:

Here's how I got it to work:

• SPLICING SETUP
  • Output options: Horizontal=3 and Vertical=3
  • Input: HDMI
• FORMAT
  • Output: All
  • Format: HDMIP60
• EDID
  • Input: 1080p>>HDMK
  • Output: Default 1080P

The Raspberry PI is a 5, which has a pretty fast cpu, and it's fast enough so that the PI finally feels like a real computer. It has a 32G micro SD card, and it's loaded with Deiban Trixie released 2025-10-01.

When it booted up for the first time, an account called "physics" was made. The password is the same as the account name.

Here is a photo of the back of the Raspberry PI, showing how it's hooked up.

It's connected to the campus wifi network "umd-iot". This is a special wifi network that allows the gadget to go out, but no ports are open for anything to come in. So you can run a web browser but not a web server. You can run ssh and scp to copy things in and out but you can't run a ssh server to connect to it from outside. And you can't run a VNC server, unfortunately.

The wifi MAC address is 2C:CF:67:F1:BF:7B, and campus has used that MAC address to allow access to umd-iot. The password for access is hgeUVKJd5jGD. When the PI boots up, it will automatically connect.

After the first boot with network access, the computer OS was updated using:

    sudo apt update
    sudo apt upgrade -y

The PI has 2 monitors hooked up: a touch screen monitor that will show the GUI used to control the video wall, and a HDMI monitor that can go out to the wall. Turns out that the system treats these two monitors in an integrated way, with the monitors having absolute coordinates. So it's important that the system knows which monitor is on the right and which on the left (yes, it's a bit ridiculous). The way things are set up is that the HDMI is on the left, and the touch screen on the right. The resolution, orientation, etc are all controlled by right clicking on the desktop, selecting "Control Centre", and scroll down to "screens". Then right click on each monitor and adjust accordingly. The "Control Centre" at "Screens" looks like this:

This has all been preset, but to see the monitor settings, run

    xrandr --listmonitors

    Monitors: 2
    0: +DSI-2 800/154x480/86+1920+0 DSI-2
    1: +HDMI-A-1 1920/620x1080/340+0+0 HDMI-A-1

Note that when getting everything to work, the touchscreen sometimes came up in landscape and sometimes in portrait mode, but once it was set it stays that way. As of this writing, the touch screen orientation is "inverted" so that the power and HDMI cables go up, but this might change. On the PI in the picture, right next to the touch screen cable connector to the screen there's a button you can push to power cycle the computer. This has been disabled so that the PI boots up on powerup, but it's there if you need it. This is done by modifying the PI EEPROM, and to do that you have to do this:

    sudo rpi-eeprom-update -a 

    sudo -E rpi-eeprom-config —edit

    AUTO_POWER_ON=1

The touchscreen software on the PI will automatically show a keyboard when the focus is on the touchscreen. I've disabled this by right clicking on the desktop, click on "Desktop Preferences" and scroll down to "Display". You will see that the on-screen keyboard is disabled. You won't need it since we have a keyboard in a drawer in the rack but if you do, just go to the "Display" setting and re-enable it.

Sublime_text is also installed on the PI, to do that just google how do to it and follow instructions.

Bluetooth is also installed and running on the PI if you need it. In the upper left corner of the touchscreen display you will see the red raspberry, click on that, scroll down to "Preferences", and you will see the Bluetooth controls.

Another program necessary is wmctrl. This is a command-line tool for Linux that allows users to interact with and control the X Window Manager. It is used at bootup to run a full screen version of Firefox on the HDMI monitor and the wall controller on the touchscreen. It is installed via

    sudo apt install wmctrl 

In the /home/physics/scripts director is a script called "backup.sh". This is a bash script that will back up the following directories:

        /home/physics/wall
        /home/physics/Desktop
        /home/physics/.config/autostart
        /home/physics/.congig/labwc
        /home/physics/scripts

Tripp Lite B119-002-UHD 2-Port HDMI Switch for Video and Audio