SIK Experiment Guide for Arduino - V3.3

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Contributors: HelloTechie, Toni_K
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Experiment 11: Using a Piezo Buzzer

Introduction

In this circuit, we’ll again bridge the gap between the digital world and the analog world. We’ll be using a piezo buzzer that makes a small “click” when you apply voltage to it (try it!). By itself that isn’t terribly exciting, but if you turn the voltage on and off hundreds of times a second, the piezo buzzer will produce a tone. And if you string a bunch of tones together, you’ve got music! This circuit and sketch will play a classic tune. We’ll never let you down!

Parts Needed

You will need the following parts:

Hardware Hookup

Ready to start hooking everything up? Check out the Fritzing diagram below, to see how everything is connected.

Pay special attention to the component’s markings indicating how to place it on the breadboard. Polarized components can only be connected to a circuit in one direction.

Fritzing Diagram for RedBoard

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Having a hard time seeing the circuit? Click on the Fritzing diagram to see a bigger image.

Fritzing Diagram for Arduino

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Having a hard time seeing the circuit? Click on the Fritzing diagram to see a bigger image.

Open the Sketch

Open Up the Arduino IDE software on your computer. Coding in the Arduino language will control your circuit. Open the code for Circuit 11 by accessing the “SIK Guide Code” you downloaded and placed into your “Examples” folder earlier.

To open the code go to: File > Examples > SIK Guide Code > SIK_circuit11_buzzer

You can also copy and paste the following code into the Arduino IDE. Hit upload, and see what happens!

language:cpp
 /******************************************************************
 * SparkFun Inventor's Kit
 * Example sketch 11
 * 
 * BUZZER
 * 
 * This sketch uses the buzzer to play songs.
 * The Arduino's tone() command will play notes of a given frequency.
 * 
 * This sketch was written by SparkFun Electronics,
 * with lots of help from the Arduino community.
 * (This sketch was originally developed by D. Cuartielles for K3)
 * This code is completely free for any use.
 * Visit http://learn.sparkfun.com/products/2 for SIK information.
 * Visit http://www.arduino.cc to learn about the Arduino.
 * 
 * Version 2.0 6/2012 MDG
 * Version 2.1 9/2014 BCH
 *****************************************************************/



const int buzzerPin = 9;    // connect the buzzer to pin 9
const int songLength = 18;  // sets the number of notes of the song

// Notes is an array of text characters corresponding to the notes
// in your song. A space represents a rest (no tone)

char notes[songLength] = {
  'c', 'd', 'f', 'd', 'a', ' ', 'a', 'g', ' ', 'c', 'd', 'f', 'd', 'g', ' ', 'g', 'f', ' '}; 

// beats[] is an array of values for each note. A "1" represents a quarter-note, 
// "2" a half-note, and "4" a quarter-note.
// Don't forget that the rests (spaces) need a length as well.

int beats[songLength] = {
  1, 1, 1, 1, 1, 1, 4, 4, 2, 1, 1, 1, 1, 1, 1, 4, 4, 2};

int tempo = 113;  // The tempo is how fast to play the song (beats per second).

void setup() 
{
  pinMode(buzzerPin, OUTPUT);  // sets the  buzzer pin as an OUTPUT
}


void loop() 
{
  int i, duration; //

  for (i = 0; i < songLength; i++) // for loop is used to index through the arrays
  {
    duration = beats[i] * tempo;  // length of note/rest in ms

    if (notes[i] == ' ')          // is this a rest? 
      delay(duration);            // then pause for a moment
    else                          // otherwise, play the note
    {
      tone(buzzerPin, frequency(notes[i]), duration);
      delay(duration);            // wait for tone to finish
    }
    delay(tempo/10);              // brief pause between notes
  }

  while(true){
  // We only want to play the song once, so we pause forever
  }
  // If you'd like your song to play over and over, remove the while(true)
  // statement above
}

int frequency(char note) 
{
  int i;
  const int numNotes = 8;  // number of notes we're storing
  char names[numNotes] = { 
    'c', 'd', 'e', 'f', 'g', 'a', 'b', 'C'    };
  int frequencies[numNotes] = {
    262, 294, 330, 349, 392, 440, 494, 523    };

  // Now we'll search through the letters in the array, and if
  // we find it, we'll return the frequency for that note.

  for (i = 0; i < numNotes; i++)  // Step through the notes
  {
    if (names[i] == note)         // Is this the one?
    {
      return(frequencies[i]);     // Yes! Return the frequency and exit function.
    }
  }
  return(0);  // We looked through everything and didn't find it,
  // but we still need to return a value, so return 0.
}

Code To Note

char notes[] = "cdfda ag cdfdg gf ";

char names[] = {'c','d','e','f','g','a','b','C'};

Up until now we’ve been working solely with numerical data, but the Arduino can also work with text. Characters (single, printable, letters, numbers and other symbols) have their own type, called “char”. When you have an array of characters, it can be defined between double-quotes (also called a “string”), OR as a list of single-quoted characters.

tone(pin, frequency, duration);

One of Arduino’s many useful built-in commands is the tone() function. This function drives an output pin at a certain frequency, making it perfect for driving buzzers and speakers. If you give it a duration (in milliseconds), it will play the tone then stop. If you don’t give it a duration, it will keep playing the tone forever (but you can stop it with another function, noTone() ).

What You Should See

You should see - well, nothing! But you should be able to hear a song. If it isn’t working, make sure you have assembled the circuit correctly and verified and uploaded the code to your board or see the troubleshooting section.

Real World Application

Many modern megaphones have settings that use a loud amplified buzzer. They are usually very loud and quite good at getting people’s attention.

Troubleshooting

No Sound

Given the size and shape of the piezo buzzer it is easy to miss the right holes on the breadboard. Try double checking its placement.

Can’t Think While the Melody is Playing

Just pull up the piezo buzzer or one of the wires whilst you think, upload your program then plug it back in.

Feeling Let Down and Deserted

The code is written so you can easily add your own songs.