How to develop a smart home status monitoring tool based on MQTT? It sounds very “high-tech”, right? But don’t worry, I will guide you step by step in the simplest language, so even if you are new to Python, you can easily follow along. If you are interested in smart lights, smart thermostats, or smart plugs at home, this article will definitely be useful for you.
With this tool, we can monitor the status of smart devices at home in real-time, such as whether the lights are off, what the room temperature is, and whether appliances are consuming too much power. Next, we will break down each step of the development process and explain how this technology can be applied in real life.
What is MQTT?
Before we start coding, let’s understand the basics. MQTT (Message Queuing Telemetry Transport) is a lightweight communication protocol, very suitable for communication between IoT (Internet of Things) devices. In simple terms, MQTT is like a “radio broadcast”:
－ Devices listen to broadcasts by subscribing to channels.
－ When a device “speaks”, it sends messages to all devices subscribed to the same channel via publishing.
Why use MQTT? Because it is very bandwidth-efficient, suitable for resource-limited small devices, such as smart bulbs or sensors at home.
Requirement Analysis: What do we want to do?
The goal is to develop a tool that can:
1. Monitor in real-time the status of various smart devices at home, such as whether the lights are on and what the temperature is.
2. Transmit status data via MQTT, making it easy to connect more smart devices.
3. Provide a simple console to display device statuses.
Applicable Scenarios:
－ On your way home from work, want to know if you forgot to turn off the lights?
－ Want to monitor indoor temperature and humidity in real-time to optimize air conditioning energy efficiency.
－ Want to track electricity usage to avoid exceeding your budget.
Technical Breakdown
To achieve this tool, we need the following steps:
1. Set up an MQTT server: We will use an open-source tool like Mosquitto as a message broker.
2. Write a Python client for the device side: Simulate smart devices and publish their status messages.
3. Write a Python client for the monitoring side: Subscribe to these status messages and display them in real-time on the console.
Below are the detailed implementation steps:
1. Set up the MQTT server
The first step is to set up a local or cloud-based MQTT server.
We recommend using Eclipse Mosquitto because it is simple to use and free open-source.
Install Mosquitto:
1. Open the terminal and run the following command to install:
sudo apt-get update
sudo apt-get install mosquitto mosquitto-clients2. After installation, start the service:
sudo systemctl start mosquittoIf you are using Windows or macOS, you can also go to the Mosquitto official website to download the installation package and follow the instructions step by step.
Test the MQTT server:
To ensure the installation was successful, we will use the tools that come with Mosquitto to test:
1. Start a subscriber:
mosquitto_sub -t "test/topic" -h localhost2. Then start a publisher:
mosquitto_pub -t "test/topic" -m "Hello MQTT" -h localhostIf you see `Hello MQTT` in the subscriber window, your MQTT server is working normally!
2. Simulate smart devices (publisher)
With the MQTT server set up, we will now use Python to simulate a smart device, such as a smart bulb. We will use a library called paho-mqtt, so let’s install it first:
pip install paho-mqttHere is a code example:
import paho.mqtt.client as mqtt
import time
import random
# MQTT server information
BROKER = "localhost"
PORT = 1883
TOPIC = "home/devices/light"
# Simulate device status publishing
def publish_device_status():
client = mqtt.Client()
client.connect(BROKER, PORT, 60)
try:
while True:
# Simulate light status: ON/OFF
light_status = random.choice(["ON", "OFF"])
client.publish(TOPIC, f"Light is {light_status}")
print(f"Published: Light is {light_status}")
time.sleep(5) # Publish status every 5 seconds
except KeyboardInterrupt:
print("Device simulation stopped")
finally:
client.disconnect()
if __name__ == "__main__":
publish_device_status()Explanation:
－ `BROKER` and `PORT`: Specify the MQTT server address.
－ `client.publish`: Publish the status to the specified topic (“home/devices/light”).
－ Simulated status: Here we use random.choice to randomly generate the light’s ON/OFF status.
After running this script, it will publish the light’s status every 5 seconds.
3. Develop the monitoring tool (subscriber)
Next, we will develop a monitoring tool that can subscribe to these messages.
import paho.mqtt.client as mqtt
# MQTT server information
BROKER = "localhost"
PORT = 1883
TOPIC = "home/devices/#"
# Callback function - receive messages
def on_message(client, userdata, message):
print(f"Received message: {message.payload.decode()} from topic: {message.topic}")
# Subscribe to device status
def monitor_devices():
client = mqtt.Client()
client.on_message = on_message
client.connect(BROKER, PORT, 60)
client.subscribe(TOPIC)
print(f"Monitoring devices on topic {TOPIC}...")
try:
client.loop_forever()
except KeyboardInterrupt:
print("Monitoring tool stopped")
finally:
client.disconnect()
if __name__ == "__main__":
monitor_devices()Explanation:
－ Subscribe to all device statuses: Subscribe to all subtopics through “home/devices/#”.
－ `on_message` callback function: Prints the message when it arrives.
After running this script, you will see the light status output in real-time on the console.
Project Expansion Directions
At this point, we have completed a simple MQTT status monitoring tool, but there are many areas for expansion:
1. GUI interface: Create a graphical interface using tkinter or PyQt.
2. Remote deployment: Deploy the MQTT server to the cloud to support external access.
3. Support for more devices: Add temperature and humidity sensors, power monitors, etc.
Peng Peng Talks Technology
Through this tool, we have experienced how to use MQTT to build a smart home status monitoring system. The lightweight and efficient nature of MQTT makes it the preferred protocol in the IoT field, while Python provides flexibility and simplicity, making development easier.
The core value of this project lies in:
－ Simplifying home management: Keep track of device statuses anytime, ensuring peace of mind.
－ Learning new skills: Understand IoT communication protocols and enhance programming abilities.
On the journey of learning programming, the most important thing is to maintain curiosity and continuously try new technologies. I hope everyone can gain a deeper understanding of Python and MQTT through this article. If you find it helpful, remember to like and follow! Finally, I wish everyone success at work and happiness in life!