Brought to you by Abraxas3D and Skunkwrx.
Based on the Wall of Bender and the Wall of JoCo.
The Wall of Trans-Ionospheric is a logger and display board for the Trans-Ionospheric badge. The badge has a Bluetooth Low Energy (BLE) radio. Each badge is constantly transmitting its unique ID, player name, and other game info in BLE advertisement format. The Wall listens for these advertisements, logs them all to a file, and displays them in a friendly format for the amusement and edification of passers-by.
Three windows are displayed. A smaller window displays just the names and unique IDs of each and every badge advertisement received, in real time, even if they go by too fast to read. A bigger window displays the same information plus a time-since-last-heard indication, and scrolls the entire stored list, after removing duplicates based on the BLE advertising address transmitted. In between, another scrolled window shows just the names received, regardless of which badge sent them.
We deployed the Wall of Trans-Ionospheric on a Raspberry Pi Zero W.
The Raspberry Pi Zero W does not have an on-board realtime clock, so we added an Adafruit PiRTC Real Time Clock based on the PCF8523 chip, so that the timestamps in the log files would be accurate. (This is a different realtime clock board than we used on the Wall of JoCo. It is more convenient to install on a Raspberry Pi.)
We used a LG 24M38H HDMI monitor at 1920x1080 ("Full HD" 1080P) resolution. Note that the Wall is hard-coded for this resolution and will look terrible at any other resolution.
We ran Raspbian Jessie on a 32GB SD card. This was created using NOOBS 2.8.1 to install Raspbian Stretch.
The Wall needs networking permissions to operate the Bluetooth socket
interface. This could be accomplished by running as root but that's a
bad idea. Instead, we want to grant ourselves the appropriate capabilities.
But we're a script running under the Python interpreter, so actually we
needed to grant those capabilities to the interpreter. We didn't want to do
that for every Python program, so we made a private copy of the interpreter
and granted the capabilities to that. Like so:
cp /usr/bin/python3 capython3
sudo setcap 'cap_net_raw,cap_net_admin+eip' capython3
We then put that private interpreter in the shebang line at the top of
walloftio.py, so it gets the needed permissions if run like so:
./walloftio.py
sudo apt-get install python3-pil.imagetk libnfc-dev
sudo pip3 install gatt
sudo pip install nfcpy subprocess32 wiringpi2
In addition, you'll need to have the font Droid Sans Mono installed
in one of the usual locations for fonts, such as ~/.fonts. A zip file
of this font is included. Unzip it and move the .ttf file to a fonts
directory.
Everything else needed was already included in the NOOBS install of Raspbian. Note that this includes some dependencies that are only needed if NFC is used as in the Wall of JoCo.
We turned off screen blanking as suggested on this web page by adding
[SeatDefaults]
xserver-command=X -s 0 -dpms
in the file /etc/lightdm/lightdm.conf .
If the Wall crashes or is killed after Bluetooth initialization, it can leave the interface(s) in an unusable condition. It can usually be recovered like so:
sudo hciconfig hci0 down
sudo hciconfig hci0 up
If that doesn't work, a reboot probably will.
The system auto-starts on boot by running ~/runwot.sh. That in turns runs
walloftio.py in a terminal, so that it can display trace and error
information. The terminal is normally invisible behind the Wall display.