Christmas tree control circuit
This section describes the electronics part of the project. It uses the PIC12F683 microcontroller that operates at 4.0MHz using the internal clock source and drives 20 LEDs through 5 I/O pins (GP0, GP1, GP2, GP4, and GP5) using the Charlieplexing technique. The 20 LEDs are connected to the five Charlieplexing signal lines (named A through E) as shown in the figures below. Multiple color LEDs are chosen to make the Christmas tree colorful and attractive.
Construction of tree
First of all, make a paper layout of the tree and stick it on a cardboard or a foam board using glue. I am using the 0.2″ thick black foam board from Dollar Tree. Mark the places where you want to place LEDs on your Christmas tree. Next drill two holes (approximately 0.1″ apart) for LED legs at each marked LED position. Then cut the foam board along the layout of the tree. These steps are illustrated in the following pictures.
For more detail: Making a mini LED Christmas tree