Today I decided to use the small 2x2x2 cube to demonstrate multiplexing and so I got out my breadboard and connected it in most simple way possible. All six cube pins go directly into the Arduino IO pins. I uploaded the program which I mentioned in one of the previous posts and it worked right away. It is actually bad to connect the LEDs directly to the Arduino without any resistor in between but the Arduino is very forgiving and works with like that with smaller loads. This should not be a permanent design pattern however. The video shows that the LEDs can not be addressed individually when powering both layers because they share cathodes horizontally and their anodes vertically. Therefor its not possible to switch on the upper left and the lower right LED individually at the same time as all the other LEDs in the same column would light up as well. This is shown in the beginning of the video. To solve this problem the layers are switched on one after another in such a fast way that the human eye does not recognize it. This is the basic principle for most kinds of LED matrices. Again the corresponding program is trivial. Next up: Bigger cubes and more advanced techniques.