What’s better than a single LED? Lots of LEDs! A fun way to make a small display is to use an 8×8 matrix or a 4-digit 7-segment display. Matrices like these are ‘multiplexed’ – so to control 64 LEDs you need 16 pins. That’s a lot of pins, and there are driver chips like the MAX7219 that can control a matrix for you but there’s a lot of wiring to set up and they take up a ton of space. Here at Adafruit, we feel your pain! After all, wouldn’t it be awesome if you could control a matrix without tons of wiring? That’s where these lovely LED matrix backpacks come in. We have them in three flavors – a mini 0.7″ 8×8, a small 1.2″ 8×8 and a 4-digit 0.56″ 7-segment. They work perfectly with the matrices we stock in the Adafruit shop and make adding a bright little display trivial.

The matrices use a driver chip that does all the heavy lifting for you: They have a built in clock so they multiplex the display. They use constant-current drivers for ultra-bright, consistent colour (the images above are photographed at the dimmest setting to avoid overloading our camera!), and 1/16 step display dimming, all via a simple I2C interface. These 1.2″ matrix backpacks come with three address-selection jumpers so you can connect up to eight 1.2″ 8x8s together (or a combination, such as four 1.2″ 8x8s and four 7-segments, etc) on a single I2C bus.

The product kit comes with:

• A fully tested and assembled 1.2″ LED backpack
• Ultra-bright 1.2″ 8×8 red matrix
• 4-pin header

A bit of soldering is required to attach the matrix onto the backpack but it’s very easy to do and only takes about 5 minutes.

Of course, in classic Adafruit fashion, we also have a detailed tutorial showing you how to solder, wire and control the display. We even wrote a very nice library for the backpacks so you can get running in under half an hour, displaying images on the matrix or numbers on the 7-segment. If you’ve been eying matrix displays but hesitated because of the complexity, this is the solution you’ve been looking for!

Revision History

As of June 12, 2024– We’ve updated this PCB to have Stemma QT connectors on the I2C lines for plug-and-play usage. We’ve also updated it with Adafruit Pinguin to make a lovely and legible silkscreen.

Specifications

• This board/chip uses I2C 7-bit addresses between 0x70-0x77, selectable with jumpers.

Resources

• Tutorial and Downloads