Passive Buzzer

Overview

In this project, use these two functions to make the passive buzzer vibrate and produce sound. The function tone() generates a square wave with a specified frequency (and 50% duty cycle) on a pin. A duration can be specified, or the wave continues until noTone() is called. Similar to the active buzzer, the passive buzzer also utilizes electromagnetic induction to operate. The difference is that a passive buzzer does not have its own oscillating source, so it will not emit sound if DC signals are used.However, this allows the passive buzzer to adjust its own oscillation frequency and produce different notes such as “do, re, mi, fa, sol, la, ti”.

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
Elite Explorer Kit	300+	Elite Explorer Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION	PURCHASE LINK
Arduino Uno R4 WiFi	-
Breadboard	BUY
Jumper Wires	BUY
Resistor	BUY
Transistor	BUY
Buzzer	BUY

Wiring

Note

When connecting the buzzer, make sure to check its pins. The longer pin is the anode and the shorter one is the cathode. It’s important not to mix them up, as doing so will prevent the buzzer from producing any sound.

Schematic Diagram

Code

Note

• You can open the file 16-passive_buzzer.ino under the path of elite-explorer-kit-main\basic_project\16-passive_buzzer directly.

• Or copy this code into Arduino IDE.

At the time when you finish uploading the codes to the R4 board, you can hear a melody containing seven notes.

Code Analysis

1. Including the pitches library: This library provides the frequency values for various musical notes, allowing you to use musical notation in your code.

   Note

   Please place the pitches.h file in the same directory as the code to ensure proper functioning. pitches.h

   

   #include "pitches.h"
   

2. Defining constants and arrays:

   • buzzerPin is the digital pin on the Arduino where the buzzer is connected.

   • melody[] is an array that stores the sequence of notes to be played.

   • noteDurations[] is an array that stores the duration of each note in the melody.

   const int buzzerPin = 8;
   int melody[] = {
     NOTE_C4, NOTE_G3, NOTE_G3, NOTE_A3, NOTE_G3, 0, NOTE_B3, NOTE_C4
   };
   int noteDurations[] = {
     4, 8, 8, 4, 4, 4, 4, 4
   };
   

3. Playing the melody:

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

   • The tone() function plays a note on the buzzer for a specific duration.

   • A delay is added between notes to distinguish them.

   • The noTone() function stops the sound.

   void setup() {
     for (int thisNote = 0; thisNote < 8; thisNote++) {
       int noteDuration = 1000 / noteDurations[thisNote];
       tone(buzzerPin, melody[thisNote], noteDuration);
       int pauseBetweenNotes = noteDuration * 1.30;
       delay(pauseBetweenNotes);
       noTone(buzzerPin);
     }
   }
   

4. Empty loop function: Since the melody is played only once in the setup, there’s no code in the loop function.

5. Feel free to experiment with altering the notes and durations in the melody[] and noteDurations[] arrays to create your own melodies. If you’re interested, there is a GitHub repository (robsoncouto/arduino-songs ) that offers Arduino code for playing various songs. While their approach may differ from this project, you can consult their notes and durations for reference.