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3.2 Play Custom Tones with a Passive Buzzer

In this lesson, we’ll learn how to use a passive buzzer with the Raspberry Pi Pico 2 W to play different tones and even simple melodies! Unlike an active buzzer, a passive buzzer needs a changing electrical signal to produce sound, which means we can control the pitch of the sound by changing the signal’s frequency.

• Buzzer

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	PURCHASE LINK
Pico 2 W Starter Kit	450+	Pico 2 W Kit

You can also buy them separately from the links below.

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	Getting to Know Pico 2 W	1
2	Micro USB Cable	1
3	Breadboard	1	BUY
4	Jumper Wires	Several	BUY
5	Transistor	1(S8050)	BUY
6	Resistor	1(1KΩ)	BUY
7	Passive Buzzer	1	BUY

Understanding the Passive Buzzer

A passive buzzer works like a tiny speaker. It doesn’t produce sound on its own; instead, it needs an oscillating signal to make sound. By providing signals of different frequencies, we can make the buzzer produce different pitches, allowing us to play notes and melodies.

Schematic

In this circuit, the passive buzzer is powered through a transistor (S8050 NPN). The transistor amplifies the current, making the buzzer sound louder than if it were connected directly to the Pico.

Here’s what happens:

• GP15 outputs a high signal to control the transistor.

• When the transistor is activated, it allows current to flow through the buzzer, making it beep.

A 1kΩ resistor is used to limit the current to protect the transistor.

Wiring

Make sure you are using the passive buzzer. You can tell it’s the correct one by looking for the exposed PCB (as opposed to the sealed back, which is a active buzzer).

Writing the Code

Note

• You can open the file 3.2_custom_tone.ino under the path of pico-2w-kit-main/arduino/3.2_custom_tone.

• Or copy this code into Arduino IDE.

• Don’t forget to select the board(Raspberry Pi Pico) and the correct port before clicking the Upload button.

const int buzzerPin = 15;  // GPIO pin connected to the transistor base

void setup() {
  pinMode(buzzerPin, OUTPUT);
}

void loop() {
  // Play a tone at 440 Hz (A4 note) for 1 second
  tone(buzzerPin, 440, 1000);
  delay(1000);  // Wait for the tone to finish
  // Wait for 1 second before playing again
  delay(1000);
}

The code plays a 440 Hz tone (standard A note) for 1 second, waits for 1 second, and repeats.

• tone(pin, frequency, duration):

  • pin: The GPIO pin connected to the buzzer (through the transistor).

  • frequency: The frequency of the tone in hertz (Hz). Higher frequencies produce higher pitches.

  • duration (optional): The duration to play the tone in milliseconds.

Playing a Melody

Let’s expand the code to play a simple melody by defining the notes and their corresponding frequencies.

• An array melody[] holds the sequence of notes to play.

• An array noteDurations[] defines the duration of each note. A duration of 4 represents a quarter note.

• The for loop iterates through each note in the melody.

  • Calculates the note duration in milliseconds.

  • Uses tone() to play each note.

  • Uses delay() to pause between notes.

  • Calls noTone() to stop the tone before moving to the next note.

// Define the buzzer pin
const int buzzerPin = 15;

// Define note frequencies
#define NOTE_C4  262
#define NOTE_D4  294
#define NOTE_E4  330
#define NOTE_F4  349
#define NOTE_G4  392
#define NOTE_A4  440
#define NOTE_B4  494
#define NOTE_C5  523

// Melody notes
int melody[] = {
  NOTE_C4, NOTE_D4, NOTE_E4, NOTE_F4,
  NOTE_G4, NOTE_A4, NOTE_B4, NOTE_C5
};

// Note durations: 4 = quarter note, 8 = eighth note, etc.
int noteDurations[] = {
  4, 4, 4, 4,
  4, 4, 4, 4
};

void setup() {
  pinMode(buzzerPin, OUTPUT);
}

void loop() {
  // Iterate over the notes of the melody
  for (int thisNote = 0; thisNote < 8; thisNote++) {
    int noteDuration = 1000 / noteDurations[thisNote];
    tone(buzzerPin, melody[thisNote], noteDuration);
    // Pause between notes
    int pauseBetweenNotes = noteDuration * 1.30;
    delay(pauseBetweenNotes);
    // Stop the tone playing
    noTone(buzzerPin);
  }
  // Add a delay before repeating the melody
  delay(2000);
}

After uploading the code, you should hear the buzzer play the melody. If the sound is too quiet, ensure all connections are secure. Remember that passive buzzers may not produce very loud sounds.

Learn More

• Creating Your Own Melodies:

  You can create your own melodies by changing the melody[] and noteDurations[] arrays.

• Using the pitches.h Library:

  For convenience, you can include a library file pitches.h that contains definitions for many notes. Create a file named pitches.h and include it in your sketch.

  #include "pitches.h"
  

Further Exploration

• Compose a Song:

  Try composing your own song by defining a new sequence of notes and durations.

• Interactive Music:

  Add buttons or sensors to control the playback of the melody.

• Visual Feedback:

  Integrate LEDs to light up in sync with the notes played.

Conclusion

In this lesson, you’ve learned how to use a passive buzzer with the Raspberry Pi Pico to play different tones and melodies. By controlling the frequency of the signal sent to the buzzer, you can produce various pitches and create music in your projects.