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Lesson 32: Passive Buzzer Module

In this lesson, you will learn how to use the passive buzzer on Raspberry Pi Pico W to play single notes and perform music. You will understand how to use PWM (Pulse Width Modulation) to set up the buzzer on GPIO 16 and use the music class in the buzzer_music library to play complete songs. This course will guide you step by step through playing single notes, and then further execute full melodies such as “Happy Birthday”. This project is very suitable for beginners, providing a practical way to understand musical tones and integrate external libraries in MicroPython on Raspberry Pi Pico W.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name

ITEMS IN THIS KIT

LINK

Universal Maker Sensor Kit

94

Universal Maker Sensor Kit

You can also buy them separately from the links below.

Component Introduction

Purchase Link

Raspberry Pi Pico W

BUY

Passive Buzzer Module

BUY

Breadboard

BUY

Wiring

../_images/Lesson_32_Passive_buzzer_pico_bb.png

Code

import machine
import time

# Initialize the PWM on GPIO 16 for the buzzer
buzzer = machine.PWM(machine.Pin(16))

def tone(pin, frequency, duration):
    """Play a tone on the given pin at the specified frequency and duration."""
    pin.freq(frequency)
    pin.duty_u16(30000)
    time.sleep_ms(duration)
    pin.duty_u16(0)

# Play individual notes
tone(buzzer, 440, 250)  # A4
time.sleep(0.5)
tone(buzzer, 494, 250)  # B4
time.sleep(0.5)
tone(buzzer, 523, 250)  # C5
time.sleep(1)



# Import the music class from the buzzer_music module for easy song playback.
from buzzer_music import music

# Find some music on onlinesequencer.net, click edit, select all notes with CTRL + A and then copy them with CTRL + C
# Paste the string to song, making sure to remove the "Online Sequencer:120233:" from the start and the ";:" from the end
# https://onlinesequencer.net/2474257 Happy Birthday (by Sudirth)
song = "0 G4 3 0;3 G4 1 0;4 A4 4 0;8 G4 4 0;12 C5 4 0;16 B4 8 0;24 G4 3 0;27 G4 1 0;28 A4 4 0;32 G4 4 0;36 D5 4 0;40 C5 8 0;48 G4 3 0;51 G4 1 0;52 G5 4 0;56 E5 4 0;60 C5 4 0;64 B4 4 0;68 A4 4 0;72 F5 3 0;75 F5 1 0;76 E5 4 0;80 C5 4 0;84 D5 4 0;88 C5 8 0"

# Initialize the music class with the song and set the buzzer pin
mySong = music(song, pins=[machine.Pin(16)])

# Play music using the music class.
while True:
    print(mySong.tick())
    time.sleep(0.04)

Code Analysis

  1. Initialization

    Import necessary modules and initialize the PWM on a specific GPIO pin to control the buzzer.

    import machine
import time

# Initialize the PWM on GPIO 16 for the buzzer
buzzer = machine.PWM(machine.Pin(16))

  2. Defining the tone function

    This function allows playing a single tone at a specified frequency and duration. It sets the frequency and duty cycle (volume) of the PWM signal.

    def tone(pin, frequency, duration):
    """Play a tone on the given pin at the specified frequency and duration."""
    pin.freq(frequency)
    pin.duty_u16(30000)
    time.sleep_ms(duration)
    pin.duty_u16(0)

  3. Playing individual notes

    Here, the tone function is used to play individual notes. The parameters include the note’s frequency (in Hz) and its duration (in milliseconds).

    # Play individual notes
tone(buzzer, 440, 250)  # A4
time.sleep(0.5)
tone(buzzer, 494, 250)  # B4
time.sleep(0.5)
tone(buzzer, 523, 250)  # C5
time.sleep(1)

  4. Using the buzzer_music library

    The buzzer_music library is imported, and a song string is prepared.

    You can find some music on onlinesequencer.net, click edit, select all notes with CTRL + A and then copy them with CTRL + C. Paste the string to song, making sure to remove the “Online Sequencer:120233:” from the start and the “;:” from the end.

    For more information about the buzzer_music library, please visit james1236/buzzer_music.

    # Import the music class from the buzzer_music module for easy song playback.
from buzzer_music import music

# https://onlinesequencer.net/2474257 Happy Birthday (by Sudirth)
song = "0 G4 3 0;3 G4 1 0;4 A4 4 0;8 G4 4 0;12 C5 4 0;16 B4 8 0;24 G4 3 0;27 G4 1 0;28 A4 4 0;32 G4 4 0;36 D5 4 0;40 C5 8 0;48 G4 3 0;51 G4 1 0;52 G5 4 0;56 E5 4 0;60 C5 4 0;64 B4 4 0;68 A4 4 0;72 F5 3 0;75 F5 1 0;76 E5 4 0;80 C5 4 0;84 D5 4 0;88 C5 8 0"

  5. Initializing and playing the song

    The music class is initialized with the song string and the GPIO pin for the buzzer. The music is played in a loop using the tick method of the music class.

    # Initialize the music class with the song and set the buzzer pin
mySong = music(song, pins=[machine.Pin(16)])

# Play music using the music class.
while True:
    print(mySong.tick())
    time.sleep(0.04)