Subscribing to control topics in Raspberry Pi - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the MQTT client library.

Raspberry Pi

import [1]

Drag options to blanks, or click blank then click option'

Apaho.mqtt.client

Bmqtt.client

Cmqtt

Dpaho.mqtt

Attempts:

3 left

💡 Hint

Common Mistakes

Using just 'mqtt' or 'mqtt.client' which are not valid imports.

Forgetting the full path 'paho.mqtt.client'.

The correct import for the MQTT client in Python is paho.mqtt.client.

2fill in blank

medium

Complete the code to create a new MQTT client instance named 'client'.

Raspberry Pi

client = [1]()

Drag options to blanks, or click blank then click option'

Apaho.mqtt.Client

Bmqtt.Client

Cpaho.mqtt.client.Client

Dpaho.Client

Attempts:

3 left

💡 Hint

Common Mistakes

Using incomplete paths like 'mqtt.Client' or 'paho.Client'.

Forgetting to call the constructor with parentheses.

The MQTT client is created by calling paho.mqtt.client.Client().

3fill in blank

hard

Fix the error in the code to subscribe to the topic 'control/led'.

Raspberry Pi

client.subscribe([1])

Drag options to blanks, or click blank then click option'

A"control/led"

Bcontrol/led

C'control/led'

Dcontrol_led

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around the topic string.

Using an incorrect topic name like 'control_led'.

The topic name must be a string, so it needs quotes like 'control/led'.

4fill in blank

hard

Fill both blanks to define a callback function that prints the received message payload.

Raspberry Pi

def on_message(client, userdata, [1]):
    print('Received:', [2].payload.decode())

Drag options to blanks, or click blank then click option'

Amsg

Bmessage

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the parameter and inside the function.

Using undefined variable names.

The message parameter is commonly named msg. Use the same name to access the payload.

5fill in blank

hard

Fill all three blanks to connect to the broker, set the message callback, and start the loop.

Raspberry Pi

client.connect([1])
client.[2] = on_message
client.[3]()

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A'localhost'

Bon_message

Cloop_start

Dloop_forever

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong broker address.

Not assigning the callback correctly.

Using loop_forever() instead of loop_start() when asynchronous loop is needed.

Connect to the broker at 'localhost', assign the on_message callback, and start the loop with loop_start().