At the heart of the display is an ATMega328 which controls all the serial communications and the 4-digit 7-segment display through an easy to use API.

The Serial 7-Segment Display can be controlled in one of three ways: Serial TTL communication, SPI serial communication or I2C serial. You can even program it for stand-alone operation since the ATMega328 comes pre-loaded with the Arduino bootloader! There is also an FTDI header on board and we’ve provided a hardware profile for the Arduino IDE to make it even easier to program.

There have been some layout changes to this design as well which will make it easier to incorporate these into your project. The power and I2C pins moved  to the sides of the board so that you can chain them together in order to display longer strings of digits. There are also added mounting holes to the boards so you can mount them on standoffs (no more hot glue!)
 
Features:

• 4 digit blue alpha-numeric display with TTL, SPI or I2C Serial Interface
• Display numbers, most letters, and a few special characters
• Individual control of decimal points, apostrophe, and colon
• Selectable baud rate
• Selectable brightness
• Baud rate and brightness values retained in non-volatile memory
• Individual segment control for each digit

Useful Links:
Github Repo
Datasheet