“This is the forth cube project I have posted here. I said in the third one that it would be the last, but this cube is a whole new way to build cubes - much easier, using LEDs very similar to the programmable LEDs that Adifruit’s Neo-Pixel strips and panels use. This approach makes an LED cube that is multi-color, very bright, easy to construct and easy to program.
Usually we have external shift registers to provide the huge number of digital pins necessary to control a cube. My first three cube projects eliminated the shift registers by using the large number of digital output pins on the MEGA. But this cube is totally different. All the LEDs in this cube are wired up in a long single strand, like an LED strip, and a single digital pin on an UNO controls the whole thing. There is literally nothing to the project except an UNO, 125 programmable LEDs, and a power supply.
Let’s take a look at how this cube is built. It uses the APA-106 programmable LED. This 4 lead device contains an internal control IC which controls the brightness of the red, green and blue LEDs it contains, but also has a built in shift register, capable of recognizing the data sent to it, but also passing on the data not meant for it to other LEDs in the chain. We must provide +5 volt and ground to each LED, as well as a single data line that will run through all LEDs in the chain. Our cube is a single chain of 125 LEDs.
The APA-106 LEDs cost 20 cents each on EBAY and currently have to ship from China. So you need $25 worth of LEDs and it takes 3 weeks to get them. Regular RGB LEDs cost about 9 cents, so this approach is a little more expensive, but much, much less work!
Let’s look at some basic details of construction. The really nice thing about this cube is that it is build layer by layer. This means we can put it together in a simple jig, wiring together 25 LEDs at a time, on a mostly flat plane. This means both easy construction and a nicer looking cube, compared with regular cubes that are built in vertical panels.”