Christmas Star with 56 Neopixel LEDs

Description

A technological Christmas decoration made with 56 Neopixel LEDs and controllable with any Arduino board (not included), ideal for placing on top of the tree or wherever you like, for example on the doorstep.
The Neopixel LEDs are connected in cascade and powered in parallel; this configuration allows addressing each single LED and choosing the color individually among the 256 possible combinations for each RGB base color (so we have 256x256x256 combinations!) resulting in a total of 16,777,216 colors. The sketch we wrote and that you can download at the bottom of the page allows generating different effects as soon as power is supplied.

Neopixel

The Neopixel technology allows creating “smart” RGB LEDs with an onboard controller, easily integrable in the Arduino environment thanks to libraries that Adafruit (www.adafruit.com) makes freely available. A peculiarity of Neopixel LEDs is that they can be connected in cascade so that the data line passes from one to the next, but the price to pay is that beyond a certain number of LEDs, the management speed must be significantly reduced; because of this, if you need to create matrices to display fast graphics, you must use many lines with few LEDs each. Each RGB LED can be individually managed via a specific command inserted in the serial string and can produce up to 256 shades of its own color, resulting in a total of 16,777,216 color combinations. Neopixel is practically a solution that involves integrating a driver and its RGB LED in an SMD case, allowing direct LED-by-LED control. The data channel used for communication with the Neopixel LEDs and therefore with the strips is similar to the One-Wire type. The power supply for Neopixel LEDs is 5 volts; communication occurs at a maximum of 800 kbps. The Neopixel system command protocol involves sending groups of three bytes in a 24-bit string, each containing the lighting state of each base color (first the eight bits of green, then those of red, and finally those of green).