The backpacks 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 eight 7-segments (or a combination, such as four mini 8x8's and four 7-segments, etc) on a single I2C bus.
The product kit comes with:
- A fully tested and assembled LED backpack
- Ultra-bright 4-digit 1.2" tall red seven-segment display
- 5-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, they also have a detailed tutorial showing you how to solder, wire and control the display. They even wrote very nice libraries for the backpacks so you can get running in under half an hour, displaying numbers on the 7-segment for either Arduino or Raspberry Pi. If you've been eyeing matrix displays but hesitated because of the complexity, his is the solution you've been looking for!
TECHNICAL DETAILS
Measurements after you mount the screen:
- 50mm/2" wide
- 120mm/4.7" long
- 13mm/0.5" high
- This board/chip uses I2C 7-bit addresses between 0x70-0x77, selectable with jumpers.
- EagleCAD PCB files, datasheets, and Fritzing available in the product tutorial