Firelight

A ws2811 LED strip controller and fire effect renderer for the Raspberry Pi, together with a REST interface for remote control from an app or web interface.

This crate contains two binaries:

• The firelight-daemon speaks to the hardware using the ws2811 protocol. This must run as root since it requires direct memory access. It opens a unix domain socket where it accepts messages consisting of a sequence of raw u32 values in the format 0x00RRGGBB.

• The firelight-rest server provides a simple REST API with a /status endpoint to query the current renderer state in JSON format and a /control endpoint to set it in the same format.

Or, in a graphical

           ws2811                domain socket              Control                    ???
hardware <-------- controller  <--------------- renderer <------------ server  <------------ user

                firelight-daemon                   (lib)              firelight-rest      (e.g.) homeassistant

The daemon can only run on a Raspberry PI because it needs to know the model-specific memory offset of the video core memory and the DMA controller.

The server internally spawns a rendering thread that continually renders the RGB light values according to the current state and sends them to the daemon. The debug-shell binary can be used to just run the renderer without a web server.

Currently, two effect modes are supported by the renderer: A static mode that displays a constant color, and a fire mode that renders a roughly flame-shaped dynamic light effect.

The server assumes that the LED strip is organized into several consecutive strands. The idea is that these represent space-like separated parts of the strip, which is still connected into a single circuit. Schematically, it looks like this: