An API for lighting up my Christmas tree
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Type Name Latest commit message Commit time
Failed to load latest commit information.

Christmas Tree

An API for lighting up my Christmas tree.

Build Status


I am using the components of the Adalight: a 25 pixel RGB LED strand driven by an Arduino Uno. The standard Adalight driver program runs on the Arduino and accepts color data over USB. The Arduino presents itself as a serial device to the computer, and the christmas-tree program writes color data to the serial port.


There are two programs:

  • server, the API server that runs on a publicly accessible server. It exposes a simple API over https on one port (protected by basic auth). On a different port it listens for connecting clients. When a client connects, it the server sends it mode changes via the socket.

  • cristmas-tree, the program that runs in a local network and writes color data to the serial port. Colors are determined by the current mode, and the current mode is retrieved by connecting to the server and listening for mode changes.


To run the client on Ubuntu 16.04:

# Build the client program.
stack setup
stack build

# Give yourself permission to access /dev/ttyACM0
sudo usermod --append --groups dialout $USER

# Run the client, assuming the Arduino is at /dev/ttyACM0.
# Replace with your server domain and socket port.
stack exec christmas-tree /dev/ttyACM0


A mode is a function Float -> Integer -> Color, that takes the current time (the amount of seconds since midnight) and the LED index, and produces a color for the LED.


Christmas Tree is free software. It is licensed under the GNU General Public License, version 3.