One segment? No way dude! 7-Segments for life!
7-Segment Matrices like these are 'multiplexed' - so to control all the seven-segment LEDs you 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. 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 LED Matrix FeatherWings come in!
The 7-segment FeatherWing backpack makes it really easy to add a 4-digit numeric display with decimal points and even 'second colon dots' for making a clock.
The LEDs themselves do not connect to the Feather. Instead, a matrix driver chip (HT16K33) does the multiplexing for you. The Feather simply sends i2c commands to the chip to tell it what LEDs to light up and it is handled for you. This takes a lot of the work and pin-requirements off the Feather. Since it uses only I2C for control, it works with any Feather and can share the I2C pins for other sensors or displays.
The product kit comes with:
- A fully tested and assembled Adafruit 4-Digit 7-Segment LED Matrix Display FeatherWing
- Ultra-bright 4-digit 0.56" tall blue seven-segment display
- Two sixteen pin headers
A bit of soldering is required to attach the matrix onto the FeatherWing but its very easy to do and only takes about 5 minutes!
- This board/chip uses I2C 7-bit address between 0x70-0x77, selectable with jumpers
- FeatherWing Dimensions: 51mm x 23mm x 4.2mm / 2.0" x 0.9" x 0.165"
- Backpack Weight: 4.8g
- 7-Segment Display Dimensions: 50mm x 19mm x 14.5mm / 2.0" x 0.75" x 0.57"
- 7-Segment Display Weight: 9.1g
- EagleCAD PCB files, schematic, Arduino LED Backpack library, and Fritzing available in the product tutorial
7-Segment 0.56" 4-Digit FeatherWing Display - Blue 
- Brand: Adafruit
- Product Code: ADA-3106
- Reward Points: 14
- Availability: 1
- Ex Tax: £14.25
- Price in reward points: 200