What does a wall fitted with 90,000 APA102 programmable LEDs look like? If you happen to visit the Oregon Museum of Science, you can now find out — as long as it’s turned on that is. The giant display runs on four Spartan 6 Mojo FPGA boards, and is installed behind a wood grain pattern. This means that when its powered off, the wall looks like, well, just a wall.
To shine through the wood grain and acrylic concealing electronics within, APA102 LEDs were selected for the job because of their high brightness levels. The final display is an impressive 24’ wide x 14’ high and a total resolution of 408 x 220 — 89,760 points of light if you’re counting at home.
In action, a video signal is sent via HDMI to the four FPGA boards, which break images down into their respective pixel quadrants. Due to memory restrictions, it takes three passes to arrange the outputs, giving a final video refresh rate of 20 frames per second. Several custom shields are implemented to organize this massive wiring job, and the LED panels themselves are simply LED strips connected together in a custom pattern.
Once everything was in place, plates of acrylic were then mounted — giving it the look of a normal-ish wall with a bright secret inside!