ArduinoHA lets an Arduino, ESP8266, or ESP32 application publish MQTT discovery data that Home Assistant understands. Give it a connected Arduino Client, declare entities, and Home Assistant creates the controls and telemetry automatically.

Start with a sensor

#include <ESP8266WiFi.h>
#include <ArduinoHA.h>

WiFiClient client;
HADevice device;
HAMqtt mqtt(client, device);
HASensorNumber temperature("temperature");

void setup() {
    byte mac[WL_MAC_ADDR_LENGTH];
    WiFi.macAddress(mac);
    device.setUniqueId(mac, sizeof(mac));

    // Your application connects Wi-Fi before MQTT begins.
    temperature.setName("Temperature");
    temperature.setUnitOfMeasurement("°C");
    mqtt.begin("mqtt.local", "mqtt_user", "mqtt_password");
}

void loop() {
    mqtt.loop();
    // Call temperature.setValue(...) when your reading changes.
}

Build ESP Sensor for a complete ESP8266/ESP32 project. It clearly marks the network and broker values you must provide without committing credentials.

What you can build

Automatic Home Assistant discovery: retained MQTT discovery messages create entities without hand-written Home Assistant YAML.
Two-way controls: sensors publish state while switches, lights, covers, and other writable entities receive explicit callbacks.
One physical device: HADevice groups metadata, multiple entities, shared availability, and MQTT Last Will.
Device discovery: publish one compact discovery document for a new multi-entity device, or keep traditional per-entity discovery.
Small footprint: exclude entity implementations your firmware does not use.

Choose an example

Example	Learn how to…
ESP Sensor	connect an ESP application and publish changing numeric telemetry
Switch Callback	reflect Home Assistant commands in a physical output and report state back
Multi-entity Device	group controls and telemetry with shared availability and Last Will
Device Discovery	publish one Home Assistant device-discovery document for a new device
Entity recipes	find the existing focused Arduino sketches for each supported entity

Install

lib_deps =
    home-assistant-integration=https://github.com/alexhopeoconnor/arduino-home-assistant.git#v3.2.0

PlatformIO clones the Git repository and checks out the ref after #; that ref is a release tag, not a GitHub Release asset. Arduino IDE is supported through the included library.properties.

See getting started, the documentation map, examples, release history, and licence.