What's better than a single LED? Lots of LEDs! A fun way to make a small linear display is to use two 12-bar Bi-color bar-graphs. However, this LED bargraph is 'multiplexed' - so to control all the 48 LEDs you need a lot of pins. There are driver chips like the MAX7219 that can help control a bar-graph/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 colorful bargraph without tons of wiring? That's where this adorable LED bar-graph backpack comes in. Much like our 8x8 and 7-segment backpacks, this backpack pairs perfectly with our bar-graphs and manages all the LED control and multiplexing. 

The backpack uses a driver chip that does all the heavy lifting for you: It has a built in clock so it can multiplex the display. It uses constant-current drivers for ultra-bright, consistent color, 1/16 step display dimming, all via a simple I2C interface. The backpack comes with address-selection jumpers so you can connect up to eight of these bar-graphs on a single I2C bus. You can also mix-and-match the bar-graph breakout with our other types of I2C LED backpacks. 

The product kit comes with:

• A fully tested and assembled LED backpack stick
• Two 12-bar bi-color bar-graphs
• 4-pin header

A bit of soldering is required to attach the matrix onto the backpack but its 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 eyeing matrix displays but hesitated because of the complexity, his is the solution you've been looking for! 

Bi-Color (Red/Green) 24-Bar Bargraph w/I2C Backpack Kit (4:37)

• Bargraph Dimensions: 10mm x 30mm ( 0.4" x 1.2")
• 7mm (0.3") thick
• Lots more details including dimensions, pinouts, etc in the datasheet, this is the Common-Cathode model KWL-R1230CDUGB
• Board Dimensions: 13mm x 101mm (.5" x 4")