Lights!

Controlling an RGB LED light strip over the network via a Raspberry Pi

Features

• Should work with 12V common-anode RGB LED strips
• Web form for setting colors (color picker imported from taufik-nurrohman/color-picker, falls back to HTML5 color picker if no JavaScript)
• HTTP JSON API for setting colors, predefined patterns, or custom timed patterns
• UDP OSC API for setting colors or predefined patterns (tested from Sonic Pi)

Hardware

Note: I only know enough about electronics hardware to be dangerous. This could fry a Raspberry Pi given it is using an external (but regulated) non-USB power source or fry it for other reasons. It hasn't broken mine yet running all of the time but it is still quite possible. I'm not responsible if the hardware causes the magic blue smoke to leave your Raspberry Pi or summons demons that break your LED strip.

Parts Used

• 3x N-channel MOSFETs
• 3x 15 Ω resistors (other small resistors would work; probably not required)
• 1x ATX Power Connector Breakout Kit
• 1x Raspberry Pi (tested with RPi 4B but other models should work)

Schematic

Breadboard View

Image generated with Fritzing

Software

A Rust toolchain (stable or unstable) is required, and using rustup is recommended to ensure a current toolchain on Raspberry Pi OS. Running cargo run --release will run the daemon, which includes a light pattern animation and output thread, HTTP server, WebSocket server, and OSC server. In a deployment, the static and templates directories as well as the binary are the only artifacts needed.

API

JSON

Endpoint: /color

Methods

Method	Description
GET	Retrieve current color (including currently displayed color of pattern)
PUT	Set a solid color

Format

{
  "red": 0,
  "green": 169,
  "blue": 255
}

Endpoint: /pattern

Methods

Method	Description
GET	Retrieve current pattern
PUT	Set a new pattern

Off Pattern Format

{
  "type": "off"
}

Solid Pattern Format

{
  "type": "solid",
  "content": {
    "red": 255,
    "green": 0,
    "blue": 195
  }
}

Custom Pattern Format

Durations are in milliseconds

{
  "type": "custom",
  "content": [
    {
      "color": {
        "red": 255,
        "green": 0,
        "blue": 137
      },
      "duration": 500
    },
    {
      "color": {
        "red": 0,
        "green": 140,
        "blue": 255
      },
      "duration": 500
    },
    {
      "color": {
        "red": 255,
        "green": 255,
        "blue": 255
      },
      "duration": 500
    }
  ]
}

OSC

Address: /color

Arguments

Multiple formats accepted

red: int32
green: int32
blue: int32

red: float32
green: float32
blue: float32

red: float64
green: float64
blue: float64

color: rgba

Address: /pattern/off

Arguments

[no arguments]

Address: /pattern/solid

Arguments

Multiple formats accepted

red: int32
green: int32
blue: int32

red: float32
green: float32
blue: float32

red: float64
green: float64
blue: float64

color: rgba

WebSocket

The WebSocket interface streams color updates to the client (which includes color updates as part of timed patterns) and supports receiving messages to set solid colors.

The URI to connect to the WebSocket can be retrieved by making a GET request to the /wsinfo endpoint. If the response from /wsinfo is empty, a default of ws://<hostname>:8001/ should be assumed.

Format

{
  "red": 0,
  "green": 169,
  "blue": 255
}