NEW PRODUCT – Bi-Color (Red/Green) 12-LED Bargraph – Pack of 2 – Make a small linear display with multiple colors using this elegant bi-color LED bargraph. Only 1.2″ long, it is quite visible but not so large it wont plug into a breadboard! 24 LEDs are contained in the plastic body, 12 red 14mcd and 12 13mcd green. Every bar has two LEDs inside so you can have it display red, green, yellow or with fast multiplexing any color in between. This display is bright, beautiful and funky with nice diffused rectangular lenses for a striking look. There are 14 pins, 7 on each side, with 0.1″ spacing so you can easily plug it into a breadboard with plenty of space for wiring left over.
Since the display is multiplexed we suggest using 3 NPN transistors to drive the cathodes with microcontroller pins and then a 74HC595 to drive the 8 anodes.
There is a playground article about bargraph displays but that one is for non-multiplexed displays. You should also check out the tutorials introducing matrices for ideas on how to drive a multiplexed bargraph.
NEW PRODUCT – Bi-Color (Red/Green) 24-Bar Bargraph w/I2C Backpack Kit – 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 8×8 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!
