What could be better than one LED? Full of LEDs! It allows to realize small displays using 8x8 matrix or 7-segment 4-digit displays. Such matrices use 'multiplexing'. To control 7 LED segment, you need 14 pins. So that's a lot of pins, there are many control circuits like the MAX7219
to manage matrices but it requires a lot of connections that use a ton of space.
AdaFruit has of course found a solution to this heavy situation and has developed a breakout to control tons of LEDs matrix or segment without having to spend half of the day to make connections :-)
This breakout comes in two versions: one for controlling a 8x8 mini matrix
and 4-digit, 7-segment sections. Adding LED displays to your projects becomes totally trivial.
The Breakout + display we propose uses a control circuit that supports the arduous part of the work. It has an internal clock that it uses for multiplexing operations. It also uses a constant-current power supply, ideal for managing high-brightness devices but also preserves color consistency.
The brightness is adjustable in steps of 1/16 of the power, all via a simple I2C interface. The backpack (control board) comes with addressing connectors (jumper to weld), so it is possible to connect up to 4 8x8 matrix or 8 7-segment displays (or a combination such as 4 8x8 matrix and 4 7-segment display, etc) on a single I2C bus.
Some welding operations are needed to attach the LED/display matrix to the control board. Same for the pinHeader if you want to use it.