Several months ago, I was approached by the Portland band Starfucker (STRFKR) to build them an LED video wall for their upcoming tour. It needed to be large, bright, and durable, but also lightweight, portable, and easy to set up and tear down. They wanted to be able to plug in an iPod or iPad and play videos that are synced up along with their click track so everything goes along perfectly with the music. I enlisted the help of Alex Norman to take care of the software side of the project, and got to work trying to figure this thing out. It seemed like it could be made with mostly off-the-shelf components, and indeed that turned out to be the case. We decided that we would open-source the entire project, for the good of all mankind.
It didn’t take long to find Adafruit’s Digital Addressable RGB LED w/ PWM waterproof flexi strip, which looked like a good, simple solution for the pixels and drivers, since they all come together on a flex circuit and all you have to do is provide power and “SPI-like” data and clock signals. The LEDs are very bright, and they come in 5-meter-long strips with 32 pixels per meter. We used a total of 192 meters of strips to create a 64×96 pixel display with a 2:1 aspect ratio. The screen size is 6-1/2′ tall by 13′ wide, the entire wall is 8’x13′.
The use of the greenhouse polycarbonate panels to run the light strips through is genius. Really well done!
These LED strips are fun and glowy. There are 32 RGB LEDs per meter, and you can control each LED individually! Yes, that’s right, this is the digitally-addressable type of LED strip. You can set the color of each LED’s red, green and blue component with 7-bit PWM precision (so 21-bit color per pixel). The LEDs are controlled by shift-registers that are chained up down the strip so you can shorten or lengthen the strip. Only 2 digital output pins are required to send data down. The PWM is built into each chip so once you set the color you can stop talking to the strip and it will continue to PWM all the LEDs for you.