Aurora 9×18 is a beautiful firing sequence of 162 RGB-LEDs in a circular configuration. The color of each circle is controlled by a microcontroller (PIC24F08KA101) using a twisted form of PWM. The MCU only has one PWM module, yet Aurora is capable of 27 (9xR,G,B) independent brightness control.
The project uses an idea of combining PWM with multiplex drive to control the LED. It broke up each PWM cycle into multiple pulses, so that multiple LEDs were lit multiple times within one PWM cycle. In this way, the average outputs of LEDs are sum of the many pulses within the short period. Thus by combining more than one PWM pulses increases effective PWM resolution. This technique also helps reduce the perceived flicker of the light out of LEDs. Aurora 9×18’s LED refresh rate is about 246 Hz, but LEDs blink a lot more often. This creates the illusion of much higher refresh rate.
See Aurora 9×18 RGB LED art Video
If you want build this RGB LED art, just follow the instruction here.