Merry Christmas! This is a fun little Christmas decoration that I created as a gift to friends and family: a small circuit board in the shape of a Christmas tree, with flashing lights and decorative buttons, and a stand with has an optional nameplate.
I designed and programmed this from scratch for my closest friends and family. It’s taken me several months of engineering, but it’s been a lot of fun, and I learned a lot of new things while I built it. It’s conceptually inspired by a similar circuit that Dad and I built in the 80s from a magazine article, but this circuit uses completely different modern technology. I sent my blueprints to Macrofab, a factory in Houston to create the circuit boards, and to Jinxbot, a one-man 3D printing company in Mountain View to create the stands. I hand-programmed and signed each circuit board. In the four months I spent creating this, I went through three revisions of the circuit board (plus several smaller test designs), four revisions of the stand, and hundreds of revisions of the program. I hope you enjoy the Christmas lights in your home as much as I’ve enjoyed creating it!
The entire project is open-source; you're encouraged to modify and improve it. Many of my friends are makers, so I want to make sure that they can have extra fun by reading the details. The project is controlled by an ATtiny84A, so you can edit and upload the code right from the Arduino IDE! The firmware, debugging device, schematics, PCB design, and decorative artwork is all in GitHub.
If you just want to look at the schematics and don't have KiCAD, you can go to the "releases" tab in GitHub and download a zip file with PDFs of the schematic and PCB, Gerber files for the PCB, .hex files for the firmware, and .stl and .png files of the stand.
For technical documentation, visit the wiki. There are notes there about design decisions I've made, how to reprogram the Christmas tree, and other useful information for makers.
Contributions are very welcome! The best way to contribute is to open a pull request or issue on GitHub.
The schematic, PCB layout, decorative artwork, and firmware were all designed by Joel Holveck.
The tlc5947.h LED driver controller library was originally written by Limor Fried/Ladyada for Adafruit Industries, at https://github.com/adafruit/Adafruit_TLC5947/. The version included here has several changes to use less memory, because of the needs of the ATtiny environment. I used Adafruit products (such as the TLC5947 breakout board extensively during the development of this project, and am very grateful both for their product line and open-source contributions.
The capsense.h capacitive touch sensor library was inspired by the library created by Paul Bagder as maintained by Paul Stoffregen, at https://github.com/PaulStoffregen/CapacitiveSensor/. The implementation here is completely new, but borrows several ideas from the Badger/Stoffregen library. The Badger/Stoffregen capacitive touch library is a very simple, straightforward capacitive touch sensing library; seeing the way it was used helped convince me that the design was viable.
This project is copyright 2018 by Joel Ray Holveck. All rights reserved.
Different parts of this project are licensed differently; the licenses are in the individual directories. Generally, firmware is under GPLv3, the PCB is under the CERN OHL, and the decorative artwork is under CC-BY-SA.
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