IoT Device Control with MQTT and Webhook

This n8n workflow demonstrates how to receive commands via a webhook, process them, and then publish these commands to an MQTT broker to control IoT devices. It acts as a bridge between a web-based interface and an MQTT network, allowing for remote control of connected devices.

What it does

This workflow simplifies the process of sending commands to IoT devices by:

1. Receiving Webhook Commands: It listens for incoming HTTP requests (webhooks) that contain commands or data intended for an IoT device.
2. Processing and Formatting Data: It takes the data received from the webhook and formats it into a structured JSON object. This step ensures the data is consistent before being published to MQTT.
3. Publishing to MQTT: It publishes the processed command to a specified MQTT topic, which can then be subscribed to by IoT devices to receive and act upon the command.

Prerequisites/Requirements

• n8n instance: A running n8n instance to host and execute the workflow.
• MQTT Broker: Access to an MQTT broker (e.g., Mosquitto, HiveMQ, AWS IoT Core) where your IoT devices are connected.
• Webhook Sender: An application or service capable of sending HTTP POST requests to the n8n webhook URL.

Setup/Usage

1. Import the Workflow:

   • Save the provided JSON content as a .json file.
   • In your n8n instance, go to "Workflows" and click "New".
   • Click the three dots menu (...) in the top right and select "Import from JSON".
   • Upload the saved .json file.

2. Configure the Webhook Trigger:

   • Locate the "Webhook" node.
   • Copy the "Webhook URL" displayed in the node settings. This is the URL you will send your commands to.
   • Ensure the "HTTP Method" is set to POST (or adjust if your sending application uses a different method).

3. Configure the "Edit Fields (Set)" Node:

   • This node is used to define the structure of the data that will be sent to MQTT.
   • By default, it creates an empty JSON object. You will likely want to modify this node to extract specific fields from the incoming webhook data and format them as needed for your MQTT messages.
   • For example, if your webhook sends {"device_id": "sensor1", "command": "turn_on"}, you might configure this node to create an output like {"id": "{{ $json.device_id }}", "action": "{{ $json.command }}"}.

4. Configure the MQTT Node:

   • Locate the "MQTT" node.
   • Credentials: Click "Create New" next to the "MQTT Account" field.
     • Enter your MQTT Broker URL (e.g., mqtt://your-broker-address:1883).
     • Provide any necessary authentication details (username, password) if your broker requires them.
   • Topic: Specify the MQTT topic where commands should be published (e.g., iot/commands/device1).
   • Payload: Ensure the "Value" field for the payload is set to {{ JSON.stringify($json) }} or similar, to send the entire processed JSON object from the "Edit Fields (Set)" node as the MQTT message payload.

5. Activate the Workflow:

   • Toggle the workflow to "Active" in the top right corner of the n8n editor.

6. Send a Command:

   • Send an HTTP POST request to the Webhook URL you copied in step 2. The body of this request should contain the command data for your IoT device.
   • Example using curl:

     curl -X POST -H "Content-Type: application/json" -d '{"device_id": "light_001", "action": "toggle", "brightness": 75}' "YOUR_N8N_WEBHOOK_URL"
     

Your IoT devices subscribed to the configured MQTT topic will then receive the command and can act accordingly.