Aurora 48 is capable of individually controlling 48 Full color LEDs using a 40 pin microcontroller. The principle of operation is based on my other “Aurora”s. (see Aurora 9×18)
The circuit is relatively simple and straightforward. If you’ve seen other LED matrix type circuit, this should look familier.
In a nutshell, the 48 RGB LEDs are divided in two groups, connected in a 6:1 multiplex fashion, taking R, G, and B as bus lines, and common pin of each LED as column lines. There are two pairs of R/G/B buses. Since there are only 3 PWM outputs available on the controller used, I used a binary decoder IC to multiplex the PWM signal, to drive 6 bus lines. 3 pins are used to select one of the 6 buses, and 24 pins are used to control LEDs’ common pins.
The controller activates one bus at a time, outputs a pulse to the LED that should be lit. The actual duration that a particular LED turns on is controlled by the PWM pulse that goes into the binary decoder, 74HC238. The controller sends PWM pulses as short as 62.5 ns to as long as 12,500 ns to control the brightness.
For more detail: Aurora 48 – 48 RGB LED Sequencer