File:CharlieplexedArray3.png

Unlike a traditional x/y matrix, in a Charlieplexed matrix, each conductive element can cross every other conductive element.

The diagram shows 6 (n) conductive elements which cross each other , forming a multiplexed matrix of 36 (n^2) intersections. LEDS are shown placed at every intersection . However, conductors also cross themselves along the diagonal . Conductor 1 crosses conductor 1, conductor 2 crosses conductor 2 etc.. This means that six of these LEDS are short circuited ( e.g. D1 and D5 are short circuited ) . The 6 (n) diagonal LEDS will, therefore, never light up , as no voltage can ever develop across them. There is, therefore, no point in installing them .

This leaves 30 LEDS ( n^2 -n ) that can light up .

Conductor 1 crossing conductor 2 is distinguishable from conductor 2 crossing conductor 1 because LED polarity is reversed. This allows all ( n^2 - n ) LEDS to be uniquely addressed, and they can all be lit independently . For example, when conductor 3 is positive and conductor 2 is negative, current flows through, and lights up LED D8, but when conductor 3 is negative and conductor 2 is positive, current flows through, and lights up LED D9.These reverse polarity LED pairs are called complementary pairs.