Display active i3 workspaces on a 7-segment display
A set of programs and configuration files for displaying i3 workspaces on a display controlled by an Arduino Nano.
I started using a secondary monitor and didn't want to waste screen real estate for a status bar on it. However, peeking at the other monitor to see which workspaces are active felt awkward. This led me to create this project. The end result is a 4-digit 7-segment display that shows the active workspaces, mounted on top of my external monitor. It also shows if a workspace is visible by lighting up the dot after the corresponding workspace number.
There is no real reason to be limited to a 4-digit display, or in fact - a 7-segment display. I have workspaces 4-7 mapped to my external display. This setup works quite well for me.
- Arduino Nano. Technically any Arduino should work, but then you'll have to rewrite the pin mappings/use a library for the 7-segment display.
- 7-segment display module. Mine is labelled HS420561K-32. It's a 4-digit common-cathode unit. It's important that there is a dot after every digit so you can indicate the currently visible workspace.
- Four 220-ohm resistors and wires to connect it all up
Connect the display to your Arduino. If you want the numbers on the display to align
left, change the align_to_right symbol to false in uc/src/main.cpp. Then flash
the file to your Arduino using PlatformIO. To do that, run
the following commands in the root directory of the project:
cd uc
pio run -t upload
Wiring for a common-cathode display with the following pin arrangement (according
to the typical segment identification):
Top row - 1, a, f, 2, 3, b
Bottom row - e, d, DP, c, g, 4
Arch Linux users can use the provided PKGBUILD.
A compiler with C++17 support (clang-5+, gcc-7+), cmake 3.11+, git
pkgconf
libserial
jsoncpp
sigc++
This project also uses the i3ipcpp library which is pulled and built automatically by cmake.
Run the following commands:
cd linux
mkdir build && cd build
cmake ..
make
sudo make install
Run ws-display --help to see available configuration options.
You'll probably want to write an udev rule for the Arduino. Otherwise it might not
always get bound to the same /dev node.
Unfortunately the Arduino Nano does not have a serial id, so it's difficult to write
an udev rule for it. I found that the easiest way was to tie it to a USB
hub port. This works as long as the Arduino is always plugged into the same USB
port.
I won't go into writing udev rules here, see the 97-ws-display.rules file
for an example. I found this post helpful.
If the Arduino will always be connected to your machine you could (and should) just
start ws-display from your i3 config.
I have a laptop and a docking station to which the Arduino is connected to so I'm
using a systemd user service for starting and stopping ws-display. The systemd user
service starts ws-display as soon as the Arduino becomes available. The service
also depends on a custom i3.target which gets started by i3:
exec_always --no-startup-id systemctl --user restart i3.target
I also put systemctl --user stop i3.target in a script that runs when i3 exits. See the
systemd/ws-display.service and systemd/i3.target files.