Adafruit Bicolor LED

A fun way to create a small, colorful display is by using a 1.2" bi-color 8x8 LED matrix. Such matrices are multiplexed, meaning that to control all 128 LEDs, you need 24 pins. That's a lot of pins, and there are driver chips like the MAX7219 that can help manage a matrix, but it requires a lot of wiring and takes up a lot of space. Wouldn't it be fantastic to control a matrix without tons of cables? That's where these charming LED matrix backpacks come into play.

The matrices use a driver chip that does all the heavy lifting for you: they have a built-in clock to multiplex the display. They utilize constant current drivers for ultra-bright, consistent colors and a 1/16 step dimming of the display, all through a simple I2C interface. The backpacks come with address selection jumpers, allowing you to connect up to four mini 8x8 or eight 7-segment bi-color displays (or a combination, such as four mini 8x8 and two 7-segment and two bi-color, etc.) to a single I2C bus. This board/chip uses a 7-bit I2C address ranging from 0x70 to 0x77, which can be selected with jumpers.