MQTT Integration

This document describes how to use the MQTT integration in the ESP Sensors project.

Overview

The ESP Sensors project now supports publishing sensor data to an MQTT broker. This allows you to integrate your ESP sensors with home automation systems, dashboards, and other IoT platforms that support MQTT.

Configuration

MQTT functionality is configured in the config.json file. Here's an example configuration:

{
  "mqtt": {
    "enabled": true,
    "broker": "mqtt.example.com",
    "port": 1883,
    "client_id": "esp_sensor",
    "username": "your_username",
    "password": "your_password",
    "topic_prefix": "esp/sensors",
    "publish_interval": 60,
    "ssl": false,
    "keepalive": 60
  }
}

Configuration Options

enabled: Set to true to enable MQTT publishing, false to disable it.
broker: The address of your MQTT broker.
port: The port of your MQTT broker (typically 1883 for non-SSL, 8883 for SSL).
client_id: A unique identifier for this ESP device.
username and password: Credentials for authenticating with the MQTT broker (if required).
topic_prefix: The prefix for all MQTT topics published by this device.
publish_interval: How often to publish data (in seconds).
ssl: Set to true to use SSL/TLS for the connection.
keepalive: The keepalive interval for the MQTT connection (in seconds).

MQTT Topics

The ESP Sensors project publishes data to the following MQTT topics:

{topic_prefix}/{sensor_name}/temperature: The temperature reading.
{topic_prefix}/{sensor_name}/humidity: The humidity reading.
{topic_prefix}/{sensor_name}/data: A JSON payload containing all sensor data.

For example, with the default configuration and a DHT22 sensor, the topics would be:

esp/sensors/dht22_sensor/temperature
esp/sensors/dht22_sensor/humidity
esp/sensors/dht22_sensor/data

JSON Payload Format

The JSON payload published to the data topic has the following format:

{
  "temperature": 25.5,
  "humidity": 60.2,
  "timestamp": 1617123456,
  "unit": "C"
}

Usage

Automatic Usage

Once configured, the ESP device will automatically publish sensor data to the MQTT broker at the specified interval. No additional code is required.

To enable MQTT publishing:

Edit the config.json file to set mqtt.enabled to true.
Configure the MQTT broker address and credentials.
Restart the ESP device.

Programmatic Usage

The MQTT functionality is available as a module that can be imported and used in your own code:

from esp_sensors.mqtt import setup_mqtt, publish_sensor_data
from esp_sensors.config import get_mqtt_config, load_config

# Load MQTT configuration
config = load_config()
mqtt_config = get_mqtt_config(config)

# Set up MQTT client
mqtt_client = setup_mqtt(mqtt_config)

# Publish sensor data
if mqtt_client:
    publish_sensor_data(mqtt_client, mqtt_config, sensor, temperature, humidity)

The module provides the following functions:

setup_mqtt(mqtt_config): Sets up and connects to the MQTT broker using the provided configuration. Returns an MQTT client if successful, None otherwise.
publish_sensor_data(client, mqtt_config, sensor, temperature, humidity): Publishes sensor data to the MQTT broker. Returns True if successful, False otherwise.

Simulation Mode

In simulation mode, MQTT messages are not actually sent to a broker but are printed to the console. This allows you to test your code without an actual MQTT broker.

Dependencies

This feature requires the micropython-umqtt.simple package, which is included in the project's dependencies.

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