Building a ‘papercraft’ LED marquee #LEDs #Charlieplexing

The CrawlingRobotFortress blog posts about building a ‘papercraft’ 5×22 LED marquee.

Long, dark winter nights demand some tinkering and crafts. Arduino LED projects are fun, but custom circuit boards might not always be in the budget. Thankfully, discrete LEDs can be found on Ebay for less than 1¢ apiece, and cardboard circuits are a thing. Can we build a scrolling marquee display with nothing more than some LEDs, cardboard, and paper?

The LED marquee is laid out on cardboard, with dividers to separate pixels. A little screen on top diffuses the light.

And how to handle all the LEDs?

We will use a “Charlieplexing” layout to control many LEDs using only a few pins. This can be a difficult to lay out by hand. Thankfully, there is a trick: if we’re willing to tilt the grid diagonally, we can use a pattern that is easy to layout and assemble. The code to drive the display gets a bit confusing, but one can always manually map the LED locations one-by-one, if push comes to shove.

See the post for the full build details.