VIdeo DOOR:

In my dorm, EaST camPUS, modifying our living space is a big part of the culture. Here, we are allowed to paint our walls, build lofts, drill holes in the walls, and generally do whatever we like to make our environment unique. My door already had a mural someone had painted before, so instead of painting over it, I decided to create an electronic art installation. This project was completed in October of my freshman year.

The project consists of a motion-activated LED display that greets passersby with a continuous scrolling animation. It also checks the status of MITERS, an entirely student-run hackerspace I lead, indicating when it is open. Here is a video of it in action:

The display is controlled by a raspberry pi, running a script I wrote which can be found at this repository: https://github.com/AnhadSawhney/VideoDoor

In order for this to work, I had to flash the pi with DietPi, an extremely stripped-down minimal os. The raspberry pi is doing basically nothing other than running my code, maximizing the performance of the display. The LEDs are driven using the rpi-rgb-led-matrix library: https://github.com/hzeller/rpi-rgb-led-matrix

The LED displays are 5mm pitch (P5) 32x64 RGB LED matrix displays designed for outdoor use. (This means that they are super bright and waterproof.)

The animation I chose to show is called the blue ball machine. It’s a fairly old art project created by the YTMND internet forum. One member created the template of an animated tile with balls entering and leaving at specific times. The community quickly ran wild and contributed hundreds of such tiles, creating the collaborative art piece.

This animation was perfect for my door because of its standardized tile-based nature. As it scrolls across my door, my code automatically places new tiles where they are needed, and they fit seamlessly with the rest of the animation since everything is standardized.

This diagram explains how the door works:

The build process started with a CAD model. I modeled the displays and their mounting holes, as well as the raspberry pi and the power supply. Next, I created brackets to hold everything together, which were laser cut.

After writing the code and testing each display, everything was then screwed together and mounted to my door. I had to drill a hole in my door to pass the power cable through.

The hardest part of the project was remapping the displays. They are wired in an alternating snake pattern (as shown by the white arrows in the diagram) to keep the data cables short. (Longer data cables degrade signal quality) This means that if the image is sent straight out of the raspberry pi, it ends up looking like a jumbled-up puzzle on the screen (the 12th image shows this). In order to fix this, a remapping step has to happen before the image is sent, which “inverse-jumbles” the image, so that it comes out correctly on the display. Figuring out exactly which parts of the image went where took a lot of trial and error.