What is an Addressable LED matrix?

Addressable LEDs are controlled by just 1 (or sometimes 2) data pin(s) connected to a microcontroller board.

(Contrast this with hard-wired LED matrices, like the Colorduino, where every
single row and column is individually connected to a separate pin of the microcontoller.)

The microcontroller board driving an addressable LED matrix sends a stream of data to the
“Data In” (aka DIN) pin of the addressable LED matrix. The timing of the signals in
that stream tell the matrix which LED to illuminate and by how much. These timing signals are
interpreted by a tiny integrated circuit (you might say, a micro-micro-controller) embedded
in each and every LED in an addressable LED matrix.

Addressable LED matrices have two big advantages over hard-wired matrices like
those used with the Colorduino:

Fewer connections:
| the Colorduino requires 32 hard-wired connections between
the microcontroller and the display matrix, but an addressable LED matrix
requires only 3 (VIN, GND, and 1 or 2 data lines).

Wider variety of display sizes and shapes:
| the Colorduino microcontroller board fits a specific 8x8 RGB matrix
exactly. Addressable LED matrices are not tightly connected to any
external microcontroller board, and come in a wide variety of shapes and sizes, including
individual pixels, long strips, square and rectangular matrices, and even circular
or other special configurations.

The disadvantage of an addressable LED matrix is that some of the input power is dissipated
in each tiny microcontroller within each element of the matrix. This means more current
is required to drive them than to drive the simple Colorduino matrix.
Also, the Addressable RGB matrices are limited in the amount of power that can be applied,
because the tiny microcontrollers in each LED can overheat.

Conclusion: if you want a very bright, low-power-consuming, but fixed size RGB matrix,
use a Colorduino-like board and its accompanying matrix. If you want to build a display
with a much larger or smaller number of LEDs, then use an addressable RGB matrix.

Types of Addressable RGB LEDs

New developments in the manufacture of addressable LED strips and matrices are occurring rapidly.
Early (circa 2012), but still widely available matrices include the LPD8806 and WS2811.
Newer matrices (e.g., APA102, or even newer SK9822) are at least 10x faster than early generations
of addressable LEDs, and therefore are less prone to flicker.

This project uses an 8x8 matrix based on WS2812 chips, which are widely available at low cost (under $$9).
The total cost of the project is likely to be closer to $$20, since you’ll need: