“Charlieplexing” as a method of multiplexing LED displays has recently attracted a lot of attention because it allows you, with N I/Olines, to control N×(N–1) LEDs (reference 1 through reference 5).

Recently, we published an entry-level Arduino project with a single seven-segment LED display. Although it’s an amazing DIY project, we noted that most of the readers are looking for more advanced ...