CanHeader

homeautomation

Components for a CAN-bus home-automation system: relay/rollershutter/ light/button/sensor nodes on a shared CAN bus, bridged to MQTT (and from there to openHAB or Home Assistant) by a gateway. This repository holds the hardware (KiCad), mechanics (3D-printable enclosures), and firmware for the whole system.

Start here: docs/index.md — the full documentation index (requirements, architecture decisions, protocol specs), also built into every crate's cargo doc output and published to GitHub Pages.

Software

The firmware is Rust (#![no_std], embassy async, esp-hal), organized as one Cargo workspace under software/:

• common-core / common-hardware — CAN wire-format types and ESP32 hardware-support helpers shared by both firmware lines.
• gateway-core / gateway-hardware — the CAN↔MQTT bridge: web config UI, /control.json RPC, self- and CAN-bus OTA update, over wired Ethernet (DHCPv4 + SLAAC, no WiFi).
• cancomponents-core / cancomponents-hardware — the node firmware living on the bus: relays, rollershutters, buttons, lights.
• tools/mqtt-log-reader — a small Python tool for reading back the gateway's MQTT log/debug topics.
• sim/ — ./sim up: the unchanged gateway and node firmware in QEMU, several gateways with their nodes on virtual CAN buses; press buttons, set what the sensors measure, watch relays and frames, in a TUI, from Python scripts or in pytest.
• legacy/ — the original C++/ESP-IDF implementation, kept for reference. No longer built by CI.

Building

The *-core crates are hardware-independent and build/test on any machine with stable Rust:

cargo test -p gateway-core -p cancomponents-core -p common-core

The *-hardware crates target Xtensa (ESP32) and need Espressif's Rust toolchain fork, installed via espup:

cargo install espup
espup install
source "$HOME/export-esp.sh"   # needed once per new shell

Then, from a *-hardware crate directory (e.g. software/gateway-hardware/):

cargo run --release

cargo run flashes over USB serial and opens a monitor, via espflash (configured as each crate's custom runner in its own .cargo/config.toml).

Hardware

Relais

Disclaimer: if you put mains voltage on a relais board, make sure you know what you are doing. These components are experimental and you are in charge of your own actions. Be safe — if you're unsure, get an expert or leave it.

Three PCBs, one shared firmware, to switch power on and off:

• Solid-state relais (SSR) — mains voltage only (~230V @ 50-60Hz), up to 1A per relay, six relais sharing one 1A fuse. Be careful with capacitive/inductive loads; handles small rollershutters, heating actuators, and electro-magnetic contactors fine.
• Regular relais — up to 16A each, no on-board fuse (protect your own circuits). No arc-quenching chamber, so an electro-magnetic contactor is a better choice for heavy inductive loads (motors, frequency drives).
• Rollershutter — two cascaded relais per channel (power, then up/down), with software interlocking so up and down are never active at once.

All three use the same firmware and the same ESP32 pinning, and each has one extension port for up to 4 additional relay or sensor boards.

Lightswitch, sensors, CAN header/hub, UART adapter

Additional boards in hardware/ — see each board's own KiCad project for details; written documentation for these is still a work in progress.

CAN bus and MQTT protocol

See docs/protocol-can.md for the byte-level CAN wire format shared by every component, and software/gateway-core/docs/protocol-mqtt.md for the gateway's MQTT topic scheme. (Extension-board channel/button numbering conventions used by the node firmware — e.g. which CAN NO/button-id ranges map to which extension address — are documented at the node firmware level; docs/protocol-can.md covers the CAN frame format itself.)

CI

• CI — cargo fmt / cargo clippy for every crate, cargo nextest with coverage and an MSRV check for the *-core crates.
• Docs — cargo doc for every crate, published to GitHub Pages.
• Security audit — cargo-audit against the RustSec advisory database, on every dependency change and once daily.
• Renovate — automated dependency-update PRs, once daily.

software/legacy/ (the original C++/ESP-IDF code) is no longer built by CI — see its own README.md for the ESP-IDF build steps if you need to reproduce it.

License

GNU General Public License v3.0 (or later) — see LICENSE.

This is meant to be freely buildable, flashable, and modifiable hardware and firmware. GPLv3 was chosen deliberately: its copyleft means anything built on this stays open, and its Section 6 "Installation Information" requirement means anyone who conveys a modified version as part of a physical product also has to provide what's needed to install your own modified firmware on it — nobody gets to lock you out of hardware you own. All schematics, layouts, mechanics, tools, and software are provided so you can fix things yourself rather than throwing them away.

Contribution

Feel free to report issues or open a pull request.