– By Suraj Srinivas & Namratha K (Tech Team)
So you’re bored of spending holidays the same old way. You want to build something flashy and dazzle everyone around you. Also, you’re quite good with your hands. You like soldering and drilling and all that stuff. If so, then you might consider building an LED cube. It is guaranteed to entertain people of all ages and literally light up any party. Also, it would take only about a day or so to build it. Here we provide the basic instructions to motivate you to build your own LED cube.
First of all, you need to decide the size of your cube and buy the required number of LEDs. For example, a beginner wishing to start with a 4x4x4 cube would require 64 LEDs and for the overly enthusiastic who want to build an 8x8x8 cube would need 512 LEDs. Ensure that all the LEDs are working properly before soldering. In this tutorial we assume you want a 3x3x3 model.
The shorter leg of every led (-ve) should be bent at an angle of 90 degree.
Make 3 such layers. Connect all the longer ends together. You should have something like this:
Obviously, you think something’s not right. To control 3x3x3 = 27 LEDs, you would need 27 pins on your Arduino (or any board). Wait, Arduino? Yeah, so unfortunately, to build this thing, you would need to be at least familiar with Arduino. To be frank, it’s not that tough if you’ve done programming before in your life. Check out www.arduino.cc for more.
So now, how do you connect to all of them without it looking all ugly? I mean, would you really need 27×2 connections, 2 for each LED (power and ground) to control? Of course not! There are some clever techniques we can use to avoid that.
What we do here is called multiplexing. The idea is simple – instead of controlling each and every LED, assign some kind of short hand address to each LED, and upon using that address, you can control that particular LED. As an example, let’s say you have 8 LEDs. Written as a binary number, 7 is 111. So from 000 to 111, we have 8 LEDs in total. So if you want to access the 3rd LED, you just say 011. In this way, you only need to control 3 pins to change the state of 8 LEDs! Of course this means we would need a system that supports multiplexing.
But hold on, when are we going to do this? As a matter of fact, we just did. The act of creating the LED cube in that weird way that we did ensured that this was possible!
Now you only need to wire some 12 pins – one for each long standing lead below, and one for each layer. In this way, you can control all the LEDs individually. The above image shows the same concept in action for a 4x4x4 LED cube.
Using some clever programming and imaginative ideas, you can create multiple interesting patterns. To be frank, this is the difficult part of creating an LED cube. There is another concept called Persistence of Vision or POV, which we can use to create interesting animations. The basic concept is simple – if you change something fast enough, the eye does not notice the transition, just the change. As an example, just look at a fan when it runs at high speed. Attach a big black dot to one of the fan’s wings. When the fan’s wings move at high speeds, you see the fan tracing a circle. However, there is no circle to see! This is a simple example of POV.
In the image below, there is a motor running, with special LED lights which switch on and off in a particular way, so as to create the illusion of the text “555” being written. Again, this is an example of POV.
Using the concepts of multiplexing and POV, it is possible to create beautiful and interesting animations on your 3D LED cube!
All the best!
For more information, check out these links:
Pictures from: http://makezine.com/projects/3x3x3-led-cube-arduino-shield/
If you’re overly enthusiastic: http://www.hownottoengineer.com/projects/lc.html