Buzzer and Music with Pico 2 W

Passive buzzers allow you to create musical tones and melodies by generating PWM signals at different frequencies. By controlling the PWM frequency, you can play musical notes and even entire songs!

Active vs Passive Buzzers

There are two types of buzzers:

• Active Buzzer: Contains an internal oscillator. Apply voltage and it makes a fixed-frequency sound. Simple on/off control.
• Passive Buzzer: Requires an external signal (PWM) to produce sound. Can generate different frequencies/notes. We'll use this type for playing music.

Musical Notes and Frequencies

Each musical note corresponds to a specific frequency. For example:

Hardware Setup

Connect a passive buzzer to a PWM-capable GPIO pin:

Playing a Single Note

use embassy_rp::pwm::{Config as PwmConfig, Pwm};

// Setup PWM for buzzer
let mut pwm_config = PwmConfig::default();
pwm_config.top = 1000; // Will be adjusted per note
pwm_config.compare_a = 500; // 50% duty cycle

let mut pwm = Pwm::new_output_a(
    p.PWM_SLICE7, // GPIO 15 is on slice 7
    p.PIN_15,
    pwm_config
);

// Play middle C (262 Hz)
fn play_note(pwm: &mut Pwm, frequency: u32) {
    let top = (125_000_000 / frequency) as u16;
    pwm.set_top(top);
    pwm.set_compare_a(top / 2); // 50% duty
}

play_note(&mut pwm, 262); // C4
Timer::after_millis(500).await;
pwm.set_compare_a(0); // Stop sound

Playing a Melody

// Define notes as (frequency, duration_ms)
const MELODY: &[(u32, u32)] = &[
    (262, 400), // C4
    (294, 400), // D4
    (330, 400), // E4
    (349, 400), // F4
    (392, 400), // G4
    (440, 400), // A4
    (494, 400), // B4
    (523, 800), // C5
];

// Play the melody
for &(freq, duration) in MELODY {
    play_note(&mut pwm, freq);
    Timer::after_millis(duration).await;
    pwm.set_compare_a(0); // Small gap between notes
    Timer::after_millis(50).await;
}

Popular Melodies

You can program famous melodies like "Twinkle Twinkle Little Star", "Happy Birthday", or "Super Mario Theme" by defining the note frequencies and durations.

Advanced Features

• Rests: Use Timer delays without playing notes
• Tempo Control: Multiply all durations by a tempo factor
• Volume Control: Adjust PWM duty cycle (lower = quieter)
• Polyphony: Use multiple PWM channels for chords

Practical Applications

• Alarm systems with custom sounds
• Musical greeting cards
• Game sound effects
• Notification alerts
• Musical toys and instruments