Tutorial 8 - Buzzers

Buzzers are simple sound modules commonly used in DIY projects.
There are two types of buzzers:

• Active Buzzer

  • Has a built-in oscillator.
  • Produces a fixed tone when powered (simply ON or OFF).

• Passive Buzzer

  • Does not have a built-in oscillator.
  • Needs a changing signal (PWM) to generate sound.
  • Can play different frequencies → tones, melodies, or music.

In this tutorial, we’ll connect both buzzers to the ESP32-S3 Pico and use MicroPython to demonstrate how they work.

Components Needed #

Fritzing Diagram #

Connections (example pins):

• Active Buzzer → GPIO40
• Passive Buzzer → GPIO41
• VCC → 3.3V
• GND → GND

Demo 1 – Active Buzzer (ON/OFF) #

from machine import Pin
import utime

buzzer_active = Pin(40, Pin.OUT)

while True:
    buzzer_active.value(1)  # Turn ON
    utime.sleep(1)
    buzzer_active.value(0)  # Turn OFF
    utime.sleep(1)

Code Explanation #

• Pin(40, Pin.OUT) → GPIO40 controls the buzzer.
• value(1) → Sends HIGH (buzzer turns ON, fixed tone).
• value(0) → Sends LOW (buzzer OFF).
• Simple ON/OFF control with no pitch changes.

Demo 2 – Passive Buzzer (Tones) #

from machine import Pin, PWM
import utime

buzzer_passive = PWM(Pin(41))
buzzer_passive.duty(512)  # 50% duty cycle

notes = [262, 294, 330, 349, 392, 440, 494, 523]  # Do Re Mi Fa So La Ti Do

while True:
    for note in notes:
        buzzer_passive.freq(note)
        utime.sleep(0.3)

Code Explanation #

• PWM(Pin(41)) → Sets GPIO41 as a PWM output.
• duty(512) → 50% duty cycle (required to make sound).
• freq(note) → Sets the pitch (frequency in Hz).
• notes → A list of frequencies corresponding to music notes.
• Loop plays a simple scale.

Demo 3 – Passive Buzzer Beep Pattern #

from machine import Pin, PWM
import utime

buzzer = PWM(Pin(41))
buzzer.duty(512)

while True:
    buzzer.freq(1000)   # Beep at 1kHz
    utime.sleep(0.2)
    buzzer.duty(0)      # Silence
    utime.sleep(0.2)

Code Explanation #

• freq(1000) → Sets tone to 1 kHz.
• duty(0) → Turns sound OFF without disabling PWM.
• Alternates between sound and silence → beep effect.

Demo 4 – Playing a Song (Eine Kleine Nachtmusik) #

Now that we know how to play tones, let’s play a longer melody.
Here we’ll play Mozart – Eine Kleine Nachtmusik (simplified transcription).

from machine import Pin, PWM
import utime

buzzer = PWM(Pin(41))
buzzer.duty(512)

# Define notes (Hz)
C4 = 262
D4 = 294
E4 = 330
F4 = 349
G4 = 392
A4 = 440
B4 = 494
C5 = 523
D5 = 587
E5 = 659
F5 = 698
G5 = 784
A5 = 880

# Melody (simplified full theme)
melody = [
    G4, G4, G4, D5, G4, G4, G4, D5,
    G4, G4, G4, D5, G4, F5, E5, D5,
    C5, C5, C5, G5, F5, E5, D5, C5,
    B4, B4, B4, G5, F5, E5, D5, C5,
    A4, A4, A4, F5, E5, D5, C5, B4,
    G4, G4, G4, D5, G4, F5, E5, D5
]

durations = [
    0.3, 0.3, 0.3, 0.6, 0.3, 0.3, 0.3, 0.6,
    0.3, 0.3, 0.3, 0.6, 0.3, 0.3, 0.3, 0.6,
    0.3, 0.3, 0.3, 0.6, 0.3, 0.3, 0.3, 0.6,
    0.3, 0.3, 0.3, 0.6, 0.3, 0.3, 0.3, 0.6,
    0.3, 0.3, 0.3, 0.6, 0.3, 0.3, 0.3, 0.6,
    0.3, 0.3, 0.3, 0.6, 0.3, 0.3, 0.3, 0.6
]

for note, duration in zip(melody, durations):
    if note == 0:  # rest
        buzzer.duty(0)
    else:
        buzzer.freq(note)
        buzzer.duty(512)
    utime.sleep(duration)
    buzzer.duty(0)   # short silence between notes
    utime.sleep(0.05)

Code Explanation #

• Notes are defined as their frequencies (Hz).
• melody is a sequence of notes in the main theme.
• durations matches each note with its timing.
• The loop plays each note and adds a short pause.

Summary #

• Active Buzzer → Simple ON/OFF sound, no pitch control.
• Passive Buzzer → Requires PWM, can play tones and melodies.
• Example song (Eine Kleine Nachtmusik) shows how you can use the passive buzzer for real music.

✅ Use active buzzers for alerts (simple beeps).
✅ Use passive buzzers for music or custom sounds.