This project was created in affiliation with UW-Madison's IEEE student organization. IEEE strives to connect engineering students through social events, projects, and company tech talks. My role as a projects officer allows me to design engaging electronics for other members to recreate. More information regarding the club can be found online at https://ieee.slc.engr.wisc.edu/index.html.
Charlieplexing is a design technique used to drive multiplexed displays with limited I/O pins. The approach utilizes tri-state logic improving efficiency in comparison to regular multiplexing. This is perfect for our project due to the few pins on our chosen microprocessor, the ATtiny85pu.
Attributing the charlieplexing method to an LED coaster we can control 20 LEDs using only 6 I/O pins. By writing code in C and using the Arduino as an ISP we can upload it to the Attiny85. Through controlling each LED individually we can constantly update the matrix producing images, moving words, phrases, and animations. The schematic and pcb were designed in EasyEDA with parts from JLCPCB. The Gerber file and BOM are available upon request.
Likewise the LED PCB needs a protective covering to eradicate water. This led me to design a simplistic small figure coaster that could be printed at the schools makerspace. The design fits the coaster perfectly with a removable top kept in place with four pegs. I created the print in Inventor.