“An ATtiny85-based badge-size PCB that can display letters and numbers.
Have you ever thought of making a badge-sized PCB that can display some letters, numbers, etc… or your name?
In this project, I will be showing how I built a badge-sized ATtiny85-based LED matrix display (5x4 matrix). I have used Charliplexing technique for driving 20 LEDs using ATtiny85.
Charliplexing is a technique for driving a multiplexed display in which relatively few I/O pins on a microcontroller are used, e.g. to drive an array of LEDS. The method uses the tri-state logic capabilities of microcontroller in order to gain efficiency over traditional multiplexing.”