Minimal 2-pin Charlieplexing configuration (actually, just a complementary or anti-parallel configuration) with a common resistor to drive two identical LEDs with the minimal number of port signals (without using GND). This variant is not recommended to be used for two different kinds of LEDs, which would require two different resistors instead of one common resistor. Therefore, its usage in conjunction with a 2-pin dual-color LED in anti-parallel configuration without additional circuitry (not shown) is not recommended as well. While intended to be used to illustrate the Wikipedia article on Charlieplexing, it may also be used for other purposes, e.g. to illustrate a polarity indicator etc.
Own work
Matthiaspaul