The idea for this project began in an open source hardware community I participate in, called Franzininho, here n Brazil. We decided to have a Christmas project/challenge and the goal was to make a Christmas themed PCB using the WCH CH32V003 MCU (famously known as the "10 cent MCU" - 0,10 USD cost), a CR2032 battery and explore the microcontroller features. I decided to create this PCB that, when assembled, is not flat, but makes a 3D Christmas tree, and 16 5 mm LEDs make for the balls on the tree. By doing this project, I learned a lot about this new MCU, C embedded programming in general, and using its low power modes to save energy. The board has a button that wakes up the MCU and starts a set of 4 animations for the LEDs. After a number of cycles of each animation, the board enters standby mode. The expected life of battery in standby mode is 2.5 years, so a new battery should last until the Christmas of 2025 if the ornament is turned on sparingly.

PCB project was done using KiCad 7. Software project was done using MounRiver Studio.

All source files are available on my GitHub repository.