Email alerts on sensor thresholds in Raspberry Pi - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output when sensor value exceeds threshold?

Consider this Python code snippet running on a Raspberry Pi that reads a temperature sensor and sends an email alert if the temperature exceeds 30°C. What will be printed if the sensor reads 32°C?

Raspberry Pi

temperature = 32
threshold = 30
if temperature > threshold:
    print("Alert: Temperature too high!")
else:
    print("Temperature is normal.")

A Alert: Temperature too high!

B Temperature is normal.

C No output

D Error: sensor not found

💡 Hint

Check the condition comparing temperature and threshold.

Since 32 is greater than 30, the condition is true, so the alert message is printed.

🧠 Conceptual

intermediate

Which component is essential for sending email alerts from Raspberry Pi?

To send email alerts when a sensor threshold is crossed on a Raspberry Pi, which of the following is essential?

A SMTP server configuration

B GPIO pin setup only

C Bluetooth pairing

D LCD display connection

💡 Hint

Think about how emails are sent programmatically.

An SMTP server is needed to send emails from the Raspberry Pi using code.

🔧 Debug

advanced

Why does this email alert code fail to send?

This Python code snippet is intended to send an email alert when the sensor value is above threshold. Why does it fail to send the email?

Raspberry Pi

import smtplib
sensor_value = 45
threshold = 40
if sensor_value > threshold:
    server = smtplib.SMTP('smtp.example.com', 587)
    server.ehlo()
    server.starttls()
    server.login('[e-mail]', 'password')
    message = 'Subject: Alert\n\nSensor value exceeded threshold.'
    server.sendmail('[e-mail]', '[e-mail]', message)
    server.quit()

A Incorrect SMTP port number

B Missing server.ehlo() call before starttls()

C No subject line in the message

D Using starttls() without login

💡 Hint

Check the SMTP protocol sequence for secure connection.

The SMTP protocol requires an EHLO command before starting TLS to identify the client to the server.

📝 Syntax

advanced

Identify the syntax error in this sensor alert code

What is the syntax error in the following Python code that reads a sensor and sends an alert?

Raspberry Pi

temperature = 28
threshold = 25
if temperature > threshold:
    print('Alert: High temperature!')

A Variable names not defined

B Incorrect indentation of print statement

C Using single quotes instead of double quotes

D Missing colon ':' after if condition

💡 Hint

Check the if statement syntax carefully.

Python requires a colon ':' at the end of the if condition line.

🚀 Application

expert

How many email alerts are sent by this code?

This Python code reads sensor values from a list and sends an email alert for each value above 50. How many emails will be sent?

Raspberry Pi

sensor_values = [45, 52, 60, 48, 55]
threshold = 50
alerts_sent = 0
for value in sensor_values:
    if value > threshold:
        # send email alert (code omitted)
        alerts_sent += 1
print(alerts_sent)

A 2

B 4

C 3

D 5

💡 Hint

Count how many values in the list are greater than 50.

Values 52, 60, and 55 are above 50, so 3 alerts are sent.