2m Tall LED Display - Falling Rain
A few months ago while working on the Traveling Lights project I had a strip of leds laid out and had programmed a single dot of light to run along it, this effect while simple looked really cool so I decided to expand on it.
Prototyping
I ordered a couple of reels of WS2812 RGB leds and ended up with 6 strands of leds 1.5m long all hanging down from a cupboard, I spent a few evenings playing with the code and started to come up with a cool looking pattern. Using blue colours it kind of looked like a falling rain effect.
The idea progressed in small jumps over the next few months whenever I had a bit of time, the lights got mounted to a backing board, they then increased in length to just over 2 meters and finally an extra two strips were added bringing the total to 8 strips. There are now exactly 1000 leds which is rather pleasing considering I didn't think about the size before starting.
Construction
The lights run from a Teensy 3.2 and all connect to the PJRC OctoWS2811 adapter board, this board has built in level shifters meaning the 5v strips play nicely with the 3.3v microcontroller. You can easily do without this but I had bought one a few years earlier and never used it so I thought why not.
Each of the 8 strips connects directly to the Teensy via the adapter board, you can do this type of thing by connecting each strip end to end but the OctoWS2811 library is optimised for the multiple outputs.
To deal with the large current draw each strip is chained together for power at the top and the bottom and I feed power in from the 4 corners. Without this I was seeing a large drop in voltage from side to side and top to bottom.
The other thing that took a while to solve was the frame, I decided early on that I wanted to have frosted acrylic on the front to diffuse the light a bit but working out how everything went together took some trial and error.
In the end I came up with an acrylic box which slid over the wooden backing which held the lights, this turned out to be a really simple solution but one that looked good and was really easy to put together.
The frame is made from 3 key pieces, the front panels, narrow spacers to keep the lights off the front panel and the white edges. These pieces were all solvent welded together and all the joins were offset making for a rigid structure.
I have spent a bit of time playing around with the code but this is probably where most of the time to come will go, it would be nice to add an interactive element to it but I am not sure how that will work yet.
The code is now available on GitHub