Buzzer and TonalBuzzer in Raspberry Pi - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output when the buzzer is activated?

Consider the following Python code using the gpiozero library on a Raspberry Pi. What will be printed when the buzzer is turned on and off?

Raspberry Pi

from gpiozero import Buzzer
buzzer = Buzzer(17)
buzzer.on()
print('Buzzer is on')
buzzer.off()
print('Buzzer is off')

A RuntimeError: GPIO pin not accessible

B Buzzer is off\nBuzzer is on

C Buzzer is on\nBuzzer is off

D No output

💡 Hint

The print statements execute immediately after turning the buzzer on and off.

The code turns the buzzer on, prints 'Buzzer is on', then turns it off and prints 'Buzzer is off'. So the output is two lines in that order.

❓ Predict Output

intermediate

What frequency does TonalBuzzer play?

Given this code snippet using gpiozero's TonalBuzzer, what frequency will the buzzer play?

Raspberry Pi

from gpiozero import TonalBuzzer
buzzer = TonalBuzzer(18)
buzzer.play('C4')
print(buzzer.frequency)

A 261.63

B 440.00

C 329.63

D None

💡 Hint

C4 is middle C note frequency.

The note 'C4' corresponds to 261.63 Hz, so buzzer.frequency will be 261.63.

🔧 Debug

advanced

Why does this Buzzer code raise an error?

This code snippet raises an error. What is the cause?

Raspberry Pi

from gpiozero import Buzzer
buzzer = Buzzer()
buzzer.on()

A ValueError because pin number is negative

B RuntimeError because buzzer is already on

C SyntaxError due to missing colon

D TypeError because pin number is missing when creating Buzzer

💡 Hint

Check the Buzzer constructor requirements.

Buzzer requires a GPIO pin number argument. Omitting it causes a TypeError.

❓ Predict Output

advanced

What is the output of this TonalBuzzer sequence?

What will be printed after running this code?

Raspberry Pi

from gpiozero import TonalBuzzer
buzzer = TonalBuzzer(18)
buzzer.play('C4')
print(round(buzzer.frequency, 2))
buzzer.play('E4')
print(round(buzzer.frequency, 2))
buzzer.stop()
print(buzzer.frequency)

A 261.63\n329.63\nNone

B SyntaxError

C 261.63\n329.63\n0

D None\nNone\nNone

💡 Hint

Check the frequency attribute after play and stop.

The buzzer plays C4 (261.63 Hz), then E4 (329.63 Hz), then stops which sets frequency to None.

🧠 Conceptual

expert

Which option causes a runtime error when using TonalBuzzer?

Which of the following code snippets will cause a runtime error when executed on a Raspberry Pi with gpiozero TonalBuzzer?

A buzzer = TonalBuzzer(18)\nbuzzer.stop()

B buzzer = TonalBuzzer(18)\nbuzzer.play('Z4')

C buzzer = TonalBuzzer(18)\nbuzzer.play('A4')

D buzzer = TonalBuzzer(18)\nprint(buzzer.frequency)

💡 Hint

Check if 'Z4' is a valid musical note.

'Z4' is not a valid note, so play('Z4') raises a ValueError at runtime.