Displays

The project began with a tray of small MD0657C2-R displays I found in a surplus shop at a very low price.

To begin, I needed a way to drive those displays. I decided to use the MAX6952 chip: it's a bit pricey, but it can drive up to four displays at once and can be daisy-chained.

I created a simple PCB using the reference design from the datasheet, added a pair of pins for power and data, and had them manufactured using standard options.

Soldering was challenging. I ordered the SSOP variant of the MAX6952, which has very small pins, too small for (my) hand-soldering.

Fortunately, soldering flux turned out to be very effective. I had never used it before, but it allowed me to solder everything correctly on the first try :)

Using a Raspberry Pi Pico and some quick code, I started sending the required signals to the MAX6952, and it worked °o°

However, I discovered that I had placed the four displays on the PCB with no margin between them. This isn't a critical issue (since it's possible to create custom characters), but for text display purposes, the lack of spacing causes a loss of one column of pixels/LEDs between displays. Ideally, I should have left some space.

Panels

I wanted aesthetically pleasing backlit panels, inspired by this video or this project, so I took a similar approach.

I used semi-transparent acrylic panels, sprayed them with black paint, and let it dry. Then, I laser-cut the panel and etched the paint in a single pass.

As some tutorials suggested, it's probably best to do the laser cutting first, then paint and etch, to avoid burning residue on the paint. However, I had limited access to the laser cutter and didn't want to have alignments issues, so I chose the faster approach. At the end, the marks are only visible under certain lighting conditions.

The laser cutter software was probably the worst I’ve ever used. It took hours to get designs imported and cut correctly. Most of the time wasn’t spent cutting or etching, but manually fixing imported files for mistakes and missing elements.

I designed two panel types, both with the same dimensions:

• The first type shows a datacenter link with the name and provider - just basic shapes and text.
• The second one shows a map of datacenter locations, created manually by tracing borders over a real map background in Inkscape.

To mount the display behind the panel, I quickly designed a 3D-printed connector that holds everything in place via friction.

Finally, I added black tape to prevent backlight from bleeding through the displays - et voilà :)

Frame

Structure

The frame consists of wooden pieces cut to length and a laser-cut wooden top that aligns with the panels and includes mounting holes.

I also added internal dividers to isolate the light between each panel.

Everything is just glued or screwed together.

I should have left more margin on the wood structure for the panel, some light is leaking, but it it's fine.

Backlight

For the backlight, I used LED rings from, ordered alongside the display PCBs. These use 5050 WS2812 LEDs, which are individually addressable and can be controlled for brightness and color using common LED libraries.

Displays

The displays are also daisy-chained, with two displays per panel, one for each direction of bandwidth.

That’s when I discovered another problem: chaining more than four displays didn’t work reliably.

I suspect the Raspberry Pi Pico couldn't drive the CLK/CS lines properly across longer wires. There are...