“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).

A few articles have recently appeared describing novel ways to increase the number of LEDs a microprocessor can drive with a limited number of pins (Reference 1). The standard multiplexing technique ...