Description:
When we make our own electronic projects we always like to add an easy visible display. Also we look for affordable parts and parts that can be wired easy, and using no more pins than needed. This nice and bright display only needs 4 pins!!

Matrices like these are 'multiplexed' - so to control all the seven-segment LEDs you normally would need 14 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. After all, wouldn't it be awesome if you could control a matrix without tons of wiring? That's where these adorable LED matrix backpacks come in.

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 color (the images above are photographed at the dimmest setting to avoid overloading our camera!), 1/16 step display dimming, all via a simple I2C interface. The backpacks come with address-selection jumpers so you can connect up to four mini 8x8's or eight 7-segments (or a combination, such as four mini 8x8's and four 7-segments, etc) on a single I2C bus. Currently we have these displays in White, Blue, Green and Red colours. You need to solder the display on the breakoutboard, but this is very simple.

Specifications:

• Includes a fully tested and assembled LED backpack and
• A Ultra-bright 4-digit 15mm tall white seven-segment display
• Control via 4 pins and I2C Interface with any microcontroller
• 4-pin header is also included
• Dimensions Board: 51 x 27mm
• Dimensions Display: 12.84mm x 40.19mm

Resources:
Tutorial that explains how to work with this display.
Arduino Library