Multi-device MQTT network in Raspberry Pi - Mini Project: Build & Apply

Multi-device MQTT network

📖 Scenario: You have several Raspberry Pi devices that need to communicate sensor data to a central server using MQTT, a lightweight messaging protocol. Each device publishes its temperature readings to a shared topic. You want to collect and display these readings on the server side.

🎯 Goal: Build a simple MQTT network where multiple Raspberry Pi devices publish temperature data to a topic, and a central Python program subscribes to that topic to receive and print the data.

📋 What You'll Learn

Create a list of device names representing Raspberry Pi devices.

Set up an MQTT topic string for publishing and subscribing.

Write a loop to simulate each device publishing a temperature reading.

Write a subscriber function to receive and print messages from the MQTT topic.

💡 Why This Matters

🌍 Real World

MQTT is widely used in IoT projects to connect devices like Raspberry Pis for smart home or sensor networks.

💼 Career

Understanding MQTT and device communication is valuable for roles in IoT development, embedded systems, and network programming.

1

Create device list

Create a list called devices with these exact strings: 'pi1', 'pi2', 'pi3'.

Raspberry Pi

# Create a list called devices with 'pi1', 'pi2', 'pi3'
devices = []
# Your code here

Need a hint?

Use square brackets and quotes to create the list.

2

Set MQTT topic

Create a variable called topic and set it to the string 'home/temperature'.

Raspberry Pi

devices = ['pi1', 'pi2', 'pi3']
# Create a variable called topic and set it to 'home/temperature'
topic = ''
# Your code here

Need a hint?

Assign the string 'home/temperature' to the variable topic.

3

Simulate publishing temperature

Write a for loop using device to iterate over devices. Inside the loop, create a variable temperature set to 20 + devices.index(device) * 2 to simulate different readings.

Raspberry Pi

devices = ['pi1', 'pi2', 'pi3']
topic = 'home/temperature'
# Write a for loop to simulate publishing temperature for each device
for device in devices:
    temperature = 0
    # Your code here

Need a hint?

Use the index of the device in the list to calculate temperature.

4

Print published messages

Inside the for loop, add a print statement that outputs exactly: Publishing from {device} to {topic}: {temperature}°C using an f-string.

Raspberry Pi

devices = ['pi1', 'pi2', 'pi3']
topic = 'home/temperature'
for device in devices:
    temperature = 20 + devices.index(device) * 2
    # Print the publishing message below
    
# Your code here

Need a hint?

Use an f-string to include variables inside the print message.