Introduction: Raspberry Pi E-Waste Video Wall
This project is a video wall that both looks like it was pulled out of a campy science fiction movie and provides soft, controllable lighting to a room. I built it because I wanted a light that looked nice of its own accord and could be switched to any color from the web. The Hue kit is controllable, but it just looks like a lightbulb, which I didn’t like. I saw a pile of monitors in my company’s e-waste, and the video wall was born.
1 Ikea Kallax shelf (any size will work, but this looks best if you have a monitor for each section). These come up on craigslist pretty frequently. Cost: $30 on craigslist, closer to $70 new N 0.5”x0.5”
Angle brackets. My system is two levels wide and four high, so I used three brackets per level (one at each end and one in the middle). With 4 levels, this came to 12 brackets in total.
Wood screws: Just get a box of these - they’re handy. I used 1 per bracket, plus 9 as anchors at various parts of the cabinet
Rope: Old martial arts belts actually work wonderfully, as they can be screwed into and they stand up to a lot of abuse. Otherwise, I’m sure any standard rope would do fine.
N LCD Monitors: I used a hodgepodge of things I could scavenge from my company’s e-waste bin. Ideally, you want one monitor per shelf section, but I’m sure there are other arrangements that would work. Cost: This project would be monstrously expensive if you were to buy these, so look for e-waste. People throw out perfectly good (but outdated) monitors all the time. Failing that, thrift stores often have monitors, and you can sometimes get them for really cheap at surplus stores.
N VGA Splitters: You need one VGA splitter for the first four monitors, plus one for every three after that. Note that you have to use powered splitters, like this one: http://smile.amazon.com/Port-VGA-Video-Splitter-M... Don’t use the passive ones. They’re cheaper, but they reduce the brightness significantly, which diminishes the impact. Cost: $12 each.
1 Raspberry Pi+SD Card: I used the B+, but I’m hoping to migrate this over to a zero if I can get one. Cost: Roughly $40 for the whole setup.
1 HDMI->VGA converter: This seems primitive, but the signal needs to be analog to split easily. HDMI splitters cost more than this entire project. Cost: This was e-waste. A new one would be about $10.
N VGA Cables: One per monitor, plus one per splitter, plus one extra in case one goes bad. If any monitors have only DVI input, make sure to get an adapter for that as well. Some monitors don’t even take analog signals. You could get a vga-hdmi adapter for those, but I just toss them. Cost: Anywhere that has junk monitors also likely has a pile of these.
N power cables: One per monitor, plus one extra in case there’s a bad one. Note that not all monitors take standard power input (Dell in particular has an external brick some of the time). Cost: E-Waste. I thought I had a lot of extras until I started this project, and immediately realized that I needed to dumpster dive again, so plan ahead.
1 Ethernet cable: It’s easier than a keyboard, and the image here lends itself well to SSH. Cost: There should be at least one in any respectable scrap bin, but a new one should be about $1.
N power strips: Each splitter takes an outlet, plus one per monitor, plus one for the PI if your monitors don’t have USB power. Cost: No idea, had them in a box.
Total cost: My build was about $100. Prices may vary significantly based on availability of e-waste and craigslist materials. And now on to the build...
Step 1: Lay Out the Monitors
This step isn’t strictly necessary, but I found it helpful because it let me match the monitors to maximize the amount of screen that showed through the panes. The four on the top are the most visible, so I used the nicest monitors up there and worked my way down.
Step 2: Attach the Brackets
Screw the brackets into the back of the shelves as shown. I didn’t measure here, I just butted them up against the monitors and screwed them in.
Step 3: Tie the Monitors Down
I experimented with string, but it wasn’t as solid as I liked, so I opted for the old martial arts belts, which I screwed into the top and bottom of the cabinet. To tighten, I tied some string between the belts at the center and pulled them together. That keeps the monitors pinned against the cabinet, and the angle brackets handle the vertical stress.
A little aluminum tape helps to keep things together, too, but don't rely on it too much, because shear force will just tear it. It’s mostly there to stop things from slipping too much.
Step 4: Route the Wires
Zip ties are your friends here. There are 16 large cables coming out of the back of this version. They need to be secured to stop them from getting between the backs of the monitors and the wall (which would make the shelf jut out more than it already does). I tried to get them all in one bundle that leaves the back of the cabinet where I wanted to put the rest of the electronics
Step 5: Plug Everything In
I attached the pi and splitters to the side of the cabinet that faces my desk because I like the look of bare electronics, but you could just as easily attach it to the backs of the monitors, or drill into the side of the cabinet and put them in one of the cubbies. Note that, generally, you want to keep all the monitors the same “distance” from the pi to avoid significant brightness and distortion differences between them. In other words, if you have three splitters and eight monitors, plug the first splitter into the Pi, plug the second and third splitters into the first splitter, and plug the monitors into the second and third splitters.
Step 6: Debugging
As you can see, when I first plugged everything in, some of the monitors didn't turn on. The errors I saw were a combination of bad cables, unplugged parts, and me forgetting to screw one of them in. It might take a couple tries to get them all lit up, so make sure you have a good way of getting the cabinet up and down again quickly. Because this is all e-waste, the odds of getting at least one bad part are pretty good, so test the parts first, and plan to need a couple extra parts.
Step 7: Set Up the Software
Install Raspbian on the Pi. I used the image below, along with the instructions for a looping video: http://curioustechnologist.com/post/80836603897/r...
I attached the video I’m using here, but it’s relatively easy to make videos that will work with the wall. I used Unity and rendered it to video with FRAPS. Follow the instructions above to upload the video and get everything set up on the software side.
If you’re making your own looping video, there are a couple things I learned that might be of use to you. When creating tiling textures, you want to avoid anything that “sticks out” in the tile, because repetition of that element will break the illusion that the monitors aren’t all showing the same image. Games have the luxury of a second “detail” texture that crosses multiple tiles to break them up, but you can’t do that here without using eight raspberries. The fact it’s moving gives you some leeway, but there are limits. Try to keep the elements small, and try to avoid any obvious pattern.
Now that it's done, I'm very happy with how it turned out. If I had an unlimited budget, I'd look into getting a cabinet that fit the monitors more perfectly (they stick out a tiny bit at the sides), but the overall effect of the current version is exactly what I was going for.