Speeduino-to-MQTT

A Rust application that reads real-time engine data from a Speeduino ECU and publishes it to an MQTT broker. Supports hardware serial ports and TCP/IP bridges (WiFi, Ethernet), an interactive terminal UI for standalone/bench use, and fully optional MQTT so the app can run display-only without any broker.

Features

ECU protocol – issues the A real-time data command, parses all bytes of the response including EMAP, CAN inputs (CN01–CN16), VVT, flex fuel, boost and more.
Dual connection modes – hardware serial (/dev/ttyACM0, COM3 …) or raw TCP socket for WiFi/Ethernet–serial bridges (ESP32, Moxa, USR-VIS410, …).
Interactive TUI – when run from a terminal (TTY detected) a live four-panel dashboard is displayed: connection status, ECU gauges, live MQTT stats and a scrolling log.
Optional MQTT – set mqtt_enabled = false (or SPEEDUINO_MQTT_ENABLED=false) to run in display-only mode with no broker required.
Flexible configuration – TOML config file, environment variables with SPEEDUINO_ prefix, and automatic .env file loading from the working directory.
Systemd service – ships with a ready-made service unit; the scripts/build_packages.sh helper builds installable DEB and RPM packages.
85+ MQTT topics – every ECU parameter is published as a short three-letter code under a configurable base topic.

Testing: speeduino-serial-sim can be used to generate synthetic ECU data without a real ECU.

Running modes

Invocation	Behaviour
Terminal / bench (`ssh`, local shell)	Interactive TUI rendered via `ratatui`
`systemd` service / no TTY	Structured text logging to stdout
`mqtt_enabled = false`	No broker needed; data shown in TUI only
`mqtt_enabled = true` (default)	Data published to MQTT broker

Installation

Pre-built packages are available for all major platforms — no Rust toolchain needed.

Debian / Ubuntu

curl -fsSL https://g86racing.com/packages/apt/gpg.key | sudo gpg --dearmor \
     -o /usr/share/keyrings/speeduino-archive-keyring.gpg

echo "deb [signed-by=/usr/share/keyrings/speeduino-archive-keyring.gpg] \
     https://g86racing.com/packages/apt stable main" \
  | sudo tee /etc/apt/sources.list.d/speeduino.list

sudo apt update
sudo apt install speeduino-to-mqtt

Fedora / RHEL / Rocky Linux

sudo tee /etc/yum.repos.d/g86racing.repo <<'EOF'
[g86racing]
name=G86Racing packages
baseurl=https://g86racing.com/packages/rpm
enabled=1
gpgcheck=0
EOF

sudo dnf install speeduino-to-mqtt

macOS (Homebrew)

brew tap askrejans/g86racing
brew install speeduino-to-mqtt

To run as a background service (launchd):

brew services start askrejans/g86racing/speeduino-to-mqtt

Config is installed to $(brew --prefix)/etc/speeduino-to-mqtt/settings.toml.example.

Windows

Download the latest .zip from https://g86racing.com/packages/windows/.
Extract and copy settings.toml.example → settings.toml, then edit it.
Run interactively: .\speeduino-to-mqtt.exe --config settings.toml
Install as a Windows Service (optional, using NSSM):

nssm install speeduino-to-mqtt "C:\speeduino-to-mqtt\speeduino-to-mqtt.exe"
nssm set    speeduino-to-mqtt AppParameters "--config C:\speeduino-to-mqtt\settings.toml"
nssm start  speeduino-to-mqtt

After Linux installation

sudo cp /etc/speeduino-to-mqtt/settings.toml.example /etc/speeduino-to-mqtt/settings.toml
sudo $EDITOR /etc/speeduino-to-mqtt/settings.toml
sudo systemctl start speeduino-to-mqtt

Docker

The easiest way to run on any Linux machine or Raspberry Pi — no Rust toolchain needed.

Quick start (serial connection)

# 1 – Clone / download the repo (or just grab docker-compose.yml)
git clone https://github.com/askrejans/speeduino-to-mqtt
cd speeduino-to-mqtt

# 2 – Edit the environment variables in docker-compose.yml
#     (SPEEDUINO_MQTT_HOST, SPEEDUINO_PORT_NAME, etc.)
$EDITOR docker-compose.yml

# 3 – Build and start
docker compose up -d

# Follow logs
docker compose logs -f

Quick start (TCP / Wi-Fi bridge)

Uncomment the speeduino-to-mqtt-tcp service in docker-compose.yml and set SPEEDUINO_TCP_HOST / SPEEDUINO_TCP_PORT.

docker-compose.yml reference

All configuration is done via environment variables in docker-compose.yml — no config file editing required.

Variable	Default	Description
`SPEEDUINO_CONNECTION_TYPE`	`serial`	`serial` or `tcp`
`SPEEDUINO_PORT_NAME`	`/dev/ttyACM0`	Serial device inside the container
`SPEEDUINO_BAUD_RATE`	`115200`	Serial baud rate
`SPEEDUINO_TCP_HOST`	—	TCP bridge hostname / IP
`SPEEDUINO_TCP_PORT`	—	TCP bridge port
`SPEEDUINO_MQTT_ENABLED`	`true`	Set `false` for display-only
`SPEEDUINO_MQTT_HOST`	`localhost`	MQTT broker hostname
`SPEEDUINO_MQTT_PORT`	`1883`	MQTT broker port
`SPEEDUINO_MQTT_BASE_TOPIC`	`/GOLF86/ECU/`	Base MQTT topic prefix
`SPEEDUINO_MQTT_USERNAME`	—	Broker username (optional)
`SPEEDUINO_MQTT_PASSWORD`	—	Broker password (optional)
`SPEEDUINO_LOG_LEVEL`	`info`	`trace` \| `debug` \| `info` \| `warn` \| `error`

Using a settings.toml file instead

Mount your own config file over the default:

# docker-compose.yml
volumes:
  - ./settings.toml:/etc/speeduino-to-mqtt/settings.toml:ro

Environment variables always take priority over the file, so you can use both.

Serial port access on Linux

The container user is added to the dialout group. Ensure your host user can also access the device:

sudo usermod -aG dialout $USER   # then log out and back in

Build the image yourself

docker build -t speeduino-to-mqtt .

Building from source

Quick start

# 1 – Build
cargo build --release

# 2 – Copy and edit config
cp example.settings.toml settings.toml
$EDITOR settings.toml

# 3 – Run (TUI auto-enabled when attached to a terminal)
./target/release/speeduino-to-mqtt

# 4 – Or pass a custom config path
./target/release/speeduino-to-mqtt --config /etc/speeduino-to-mqtt/settings.toml

CLI options

Usage: speeduino-to-mqtt [options]

Options:
  -h, --help          Print help
  -c, --config FILE   Path to TOML config file (default: settings.toml)

Configuration

Copy example.settings.toml to settings.toml and adjust the values. Every setting can also be set via an environment variable with the SPEEDUINO_ prefix, or in a .env file in the working directory.

# ── Connection ──────────────────────────────────────────────────
connection_type = "serial"   # "serial" | "tcp"

# Serial (used when connection_type = "serial")
port_name  = "/dev/ttyACM0"
baud_rate  = 115200

# TCP bridge (used when connection_type = "tcp")
# tcp_host = "192.168.1.100"
# tcp_port = 23

# ── ECU protocol ────────────────────────────────────────────────
# expected_data_length = 120   # 119–256; 121 enables EMAP
# read_timeout_ms      = 2000
refresh_rate_ms        = 20

# ── MQTT ────────────────────────────────────────────────────────
mqtt_enabled    = true
mqtt_host       = "localhost"
mqtt_port       = 1883
mqtt_base_topic = "/GOLF86/ECU/"
# mqtt_username = ""
# mqtt_password = ""
# mqtt_use_tls  = false

Key environment variables:

Variable	Description
`SPEEDUINO_CONNECTION_TYPE`	`serial` or `tcp`
`SPEEDUINO_PORT_NAME`	Serial device path
`SPEEDUINO_TCP_HOST` / `SPEEDUINO_TCP_PORT`	TCP bridge address
`SPEEDUINO_MQTT_ENABLED`	`true` / `false`
`SPEEDUINO_MQTT_HOST` / `SPEEDUINO_MQTT_PORT`	Broker address
`SPEEDUINO_MQTT_USERNAME` / `SPEEDUINO_MQTT_PASSWORD`	Broker credentials
`SPEEDUINO_LOG_LEVEL`	`trace` \| `debug` \| `info` \| `warn` \| `error`

MQTT topics

All values are published to <mqtt_base_topic><CODE>, e.g. /GOLF86/ECU/RPM.

Engine basics

Code	Description
`RPM`	Engine speed (rev/min)
`TPS`	Throttle position (0–255 raw)
`MAP`	Manifold absolute pressure (kPa)
`BAR`	Barometric pressure (kPa)
`BAT`	Battery voltage (V, 1 dp)
`SCL`	Loop counter (secl)
`SYN`	Sync loss counter

Temperatures

Code	Description
`IAT`	Intake air temperature (°C)
`CLT`	Coolant temperature (°C)
`MAT`	IAT raw byte (backward-compatible)
`CAD`	Coolant raw byte (backward-compatible)
`FTP`	Fuel temperature (°C)

O2 / AFR

Code	Description
`O2P`	Primary O2 sensor
`O2S`	Secondary O2 sensor
`AFT`	AFR target (real units, 1 dp)

Fuel & injection

Code	Description
`VE1` / `VE2` / `VEC`	Volumetric efficiency current / table 1 / table 2
`PW1`–`PW4`	Injector pulse width channels 1–4 (ms, 1 dp)
`FLD`	Fuel load
`FTC`	Fuel temp correction

Ignition

Code	Description
`ADV` / `AD1` / `AD2`	Ignition advance (degrees)
`DWL`	Dwell time (ms, 1 dp)
`SPK`	Spark status bitfield
`IGD`	Ignition load

Corrections

Code	Description
`COR`	Combined corrections
`BTC`	Battery correction
`EGC`	EGO (O2) correction
`ITC`	IAT correction
`WEC`	Warm-up enrichment correction
`BRC`	Baro correction
`ASE`	After-start enrichment
`TAE`	Transient acceleration enrichment (%)

Flex fuel / ethanol

Code	Description
`ETH`	Ethanol %
`FLC`	Flex fuel correction
`FIC`	Flex ignition correction
`FBC`	Flex boost correction

Boost

Code	Description
`BST`	Boost target (kPa)
`BSD`	Boost duty cycle (%)

VVT

Code	Description
`VA1` / `VA2`	VVT 1/2 actual angle
`VT1` / `VT2`	VVT 1/2 target angle
`VD1` / `VD2`	VVT 1/2 duty cycle

CAN inputs

Code	Description
`CN01`–`CN16`	CAN input channels 1–16 (u16 each)

Miscellaneous

Code	Description
`VSS`	Vehicle speed
`GER`	Current gear
`FPR`	Fuel pressure
`OPR`	Oil pressure
`ILL`	Idle load
`MPD`	MAP dot (rate of change)
`TPD`	TPS dot
`TAD`	TPS ADC
`CIT`	Closed-loop idle target
`WMI`	WMI pulse width
`LPS`	Loops per second
`FRM`	Free RAM
`RPD`	RPM dot
`TOF`	Test output flags
`NER`	Next error code
`STA` / `ENG` / `ST3` / `ST4`	Status bitfields
`EPS`	Engine protect status
`OUT`	Output status
`SDS`	SD card / TunerStudio status
`EMP`	EMAP pressure (published only when packet ≥ 121 bytes)

Building packages

The scripts/build_packages.sh script cross-compiles for all platforms.

Targets

Platform	Arch	Rust triple	Output
Linux	x64	x86_64-unknown-linux-gnu	.deb + .rpm
Linux	arm64	aarch64-unknown-linux-gnu	.deb + .rpm
Windows	x64	x86_64-pc-windows-gnu	.zip
macOS	x64	x86_64-apple-darwin	.tar.gz
macOS	arm64	aarch64-apple-darwin	.tar.gz

Mac prerequisites

# Rust toolchain
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

# cross – Docker-based cross-compiler for Linux + Windows targets
cargo install cross
# Docker Desktop must be running (and Rosetta enabled for Apple Silicon)

# macOS SDK (already present if Xcode CLT is installed)
xcode-select --install

# macOS cross-arch targets (native cargo, no Docker needed)
rustup target add x86_64-apple-darwin aarch64-apple-darwin

# Apple Silicon: pre-install the cross-compilation toolchains that 'cross'
# needs to mount into Docker. --force-non-host allows installing toolchains
# that can't execute natively on ARM Mac but are needed inside the container.
for TRIPLE in x86_64-unknown-linux-gnu aarch64-unknown-linux-gnu x86_64-pc-windows-gnu; do
    rustup toolchain install stable-$TRIPLE --force-non-host --profile minimal
done

# Apple Silicon Docker prerequisite: enable in Docker Desktop →
#   Settings → General → "Use Rosetta for x86/amd64 emulation on Apple Silicon"

# DEB packaging tool
brew install dpkg

# RPM packaging tool
brew install rpm

Build commands

# Everything – all platforms, all arches, all package types
./scripts/build_packages.sh

# Linux only (DEB + RPM, all arches)
./scripts/build_packages.sh --platform linux

# Single format / arch
./scripts/build_packages.sh --platform linux  --arch arm64 --type deb
./scripts/build_packages.sh --platform windows --arch x64
./scripts/build_packages.sh --platform mac     --arch arm64

# Use local cargo instead of cross (you must have all toolchains installed)
./scripts/build_packages.sh --no-cross

./scripts/build_packages.sh --help

Output layout:

release/<version>/
  linux/
    deb/   *.deb (amd64, arm64)
    rpm/   *.rpm (x86_64, aarch64)
  windows/
         *.zip (x64)
  mac/
         *.tar.gz (x86_64, arm64)
         sha256sums.txt

Each Linux package:

Installs the binary to /usr/bin/speeduino-to-mqtt
Installs the systemd unit to /lib/systemd/system/speeduino-to-mqtt.service
Drops an example config at /etc/speeduino-to-mqtt/settings.toml.example
Creates a speeduino system user (in dialout + tty groups for serial access)
Enables the service on install

Related projects

speeduino-serial-sim – ECU data simulator for testing
GPS-to-MQTT – companion GPS bridge
G86 Web Dashboard – web dashboard for MQTT telemetry data

Name		Name	Last commit message	Last commit date
Latest commit History 57 Commits
scripts		scripts
src		src
.dockerignore		.dockerignore
.gitignore		.gitignore
Cargo.lock		Cargo.lock
Cargo.toml		Cargo.toml
Cross.toml		Cross.toml
Dockerfile		Dockerfile
LICENCE		LICENCE
README.md		README.md
docker-compose.yml		docker-compose.yml
example.settings.toml		example.settings.toml
speeduino-to-mqtt.service		speeduino-to-mqtt.service

Folders and files

Latest commit

History

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Speeduino-to-MQTT

Features

Running modes

Installation

Debian / Ubuntu

Fedora / RHEL / Rocky Linux

macOS (Homebrew)

Windows

After Linux installation

Docker

Quick start (serial connection)

Quick start (TCP / Wi-Fi bridge)

docker-compose.yml reference

Using a settings.toml file instead

Serial port access on Linux

Build the image yourself

Building from source

Quick start

CLI options

Configuration

MQTT topics

Engine basics

Temperatures

O2 / AFR

Fuel & injection

Ignition

Corrections

Flex fuel / ethanol

Boost

VVT

CAN inputs

Miscellaneous

Building packages

Targets

Mac prerequisites

Build commands

Related projects

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