Dan’s

This is an LED cube I built capable of individually driving any of the 27 individual LEDs at a time in either green, orange, or yellow. It is built using three layers of bi-color LEDs connected with common cathodes with each layer being a 3 x 3 grid of LEDs connected common cathode. Vertically, columns of three LEDs are connected with common anodes. The result is three cathode levels and 18 anode levels which through multiplexing and persistence can drive any LED anode individually or in an animation.

It works by refreshing each cathode level at a rate faster than the eye can perceive. Because light receptors in the eye continue to ’see’ light for about 15ms after the light has gone away, this clever trick allows the use of microcontrollers to turn on power to each cathode level, one at a time, without any visible hint of the led losing power, so long as each cathode level is refreshed at approximately 60Hz.

Because each LED in this cube has two anodes, a green side and an orange side, if both green and orange are powered at the same time, a third color, yellow, is visible. The result is a 3×3x3 cube of LEDs capable of individually driving any LED in green, orange, or yellow. Because of multiplexing, the cube can show a smooth animation using the LEDs. The project uses an Atmel ATMega168 and is programmed in AVR Assembly, with an animation written in AVR GCC.
.

To Pullman.

Oscar the dog.

Snowing outside.