Led Cube

                      

        The LED cube is made up from 64 LED's arranged into 4 layers of 16 LED's each. The display itself is multiplexed so instead of requiring 64 connections it requires one to each of the four layers and 16 to each LED in a layer making a total of 20. The cube is refreshed by a software interrupt routine with each layer active for 2 ms  so the entire cube is refreshed every 10mS (100Hz). This results in a display with no visible flicker.

         

LED Cube frame 

Controller 

             Only 16 I/O lines of Atmega 16 microcontroller are needed to control the whole cube.Each of the LED layers is arranged in a 4 x 4 matrix and controlled by a transistor in an emitter follower configuration connected to the LED anodes. When the respective layer control output from the Atmega goes high the base of the transistor is held at +5V and the emitter sits approximately 0.7 volts below this. The transistors used are 2N2222 NPN transistors, if an alternative is used it should be of similar specification, have an Ic rating of at least 1 amp and check the pin out.