Ryan Martin's Counter SAO Is a Simple Two-Digit Counter — with an Unusual Nine-Segment Display

Maker Ryan Martin has put together a two-digit nine-segment display Simple Add-On for your badge — with integrated counting functionality, triggered by on-board buttons.

"Use this handy little SAO to count whatever your heart desires: how many conversations you have at Supercon, how many times someone asks what SAO stands for, how many times someone asks 'What are you working on?'," Martin suggests of possible use-cases for his badge add-on. "By using the onboard buttons, I2C interface, or clocking the GP2 pin, the Nine Segment Counter SAO will indicate to the world whatever quantity you are keeping track of."

While Martin's board, is, effectively, a numerical LED display, it's a little unusual. First, it doesn't use the standard seven-segment numeric LEDs — opting instead for a clearer nine-segment design, which adds diagonals in the top and bottom halves of the numerals. Second, the segments themselves are part of the PCB, illuminated from behind via RGB LEDs. Finally, it includes on-board buttons — used to count up or down or to store up to 49 numbers to be held in the on-board Microchp ATtiny84's EEPROM.

Using the SAO is simple: push the button above a digit and it increments said digit by one; push the button below it, and it decrements the digit by the same value. Push the button above and below a digit simultaneously, and you can change that digit's color; the badge stores the last value for each color in EEPROM for later retrieval.

More information on the project is available on GitHub, along with the hardware design files and firmware source code, based on the work of Nathan Witmer, under the permissive MIT license.