Producing Alerts

These custom functions for producing alerts use the speaker and/or LED light:

• singleBeep() — produces a typical beep

• doubleBeep() — produces two quick beeps

• longBeep() — produces a longer beep

• playSong() — plays a song one note at a time in order

Be sure your app lists these global variables for the LED and speaker pin numbers before the setup() function:

int LED = 13;
int speaker = 9;

Be sure your app sets the pin modes for the LED and speaker within the setup() function:

    pinMode(LED, OUTPUT);
    pinMode(speaker, OUTPUT);

An alert can be used as feedback to a user when the robot's built-in D12 button is pressed. Alerts can also be useful as feedback to indicate when other events or conditions have occurred (such as: detecting an obstacle, reaching a destination, completing a task, etc.).

You can modify these custom functions (e.g., change frequency and duration of sound, etc.) and/or create your own alert functions for different situations (e.g., alarm sound, distress signal, obstacle alert, success signal, etc.).

singleBeep()

The singleBeep() custom function produces a typical beep sound:

void singleBeep() {
  digitalWrite(LED, HIGH);
  tone(speaker, 3000);
  delay(200);
  digitalWrite(LED, LOW);
  noTone(speaker);  
}

doubleBeep()

The doubleBeep() custom function produces two short, high-pitched beeps:

void doubleBeep() {
  for (int i=0; i < 2; i++) {
    digitalWrite(LED, HIGH);
    tone(speaker, 4000);
    delay(100);
    digitalWrite(LED, LOW);
    noTone(speaker); 
    delay(100);    
  }
}

longBeep()

The longBeep() custom function produces a longer, low-pitched beep:

void longBeep() {
  digitalWrite(LED, HIGH);
  tone(speaker, 1000);
  delay(750);
  digitalWrite(LED, LOW);
  noTone(speaker);
}

playSong()

You can also use the speaker to play simple music by playing a song one note at a time. Each note corresponds to a specific frequency played for a specific duration (such as: whole note, half note, quarter note, etc.).

Playing a song requires a file named notes.h that defines the specific frequencies for each note on a piano keyboard. It also defines durations (in milliseconds) for a whole note, half note, quarter note, etc. based on a defined beat length (in milliseconds). If necessary, you can modify the beat length to speed up or slow down the song.

To play a song using the speaker, your robot app will need to:

1. Add notes.h as a separate tab (separate file) in your app

2. Add an #include statement for notes.h in your app

3. Add the playNote() custom function to play musical notes

4. Create a custom function named playSong() to call the playNote() function for each note (or rest) in the song in sequence.

5. Call the playSong() function to play the song

STEP 1. Add notes.h as Separate Tab in App

In your app, create a new blank tab named notes.h:

• Arduino Create Web Editor: Click the tab with a drop-down icon, and select "New Tab." In the pop-up, enter notes.h as the name of the new tab, and click the OK button.

• Arduino IDE Desktop Editor: Click the down arrow icon in the top-right corner of the code editor window, and then select "New Tab" in the drop-down list. A small dialog will appear at the bottom of the code editor window. Enter notes.h as the name of the new file, and click the OK button.

Copy the code below, and paste it into the blank tab named notes.h:

// NEEDED TO PLAY SONG NOTE BY NOTE
// add as new tab named "notes.h"

// define beat length - can modify to speed up or slow down song
#define beatLength 200  // milliseconds per beat

// define length of each note
#define WN   beatLength*4  // whole note
#define HN   beatLength*2  // half note
#define QN   beatLength    // quarter note
#define EN   beatLength/2  // eighth note
#define SN   beatLength/4  // sixteenth note

// define frequency of each note on a piano keyboard
#define Rest 0
#define noteC0 16
#define noteCs0 17
#define noteDb0 17
#define noteD0 18
#define noteDs0 19
#define noteEb0 19
#define noteE0 21
#define noteF0 22
#define noteFs0 23
#define noteGb0 23
#define noteG0 25
#define noteGs0 26
#define noteAb0 26
#define noteA0 28
#define noteAs0 29
#define noteBb0 29
#define noteB0 31
#define noteC1 33
#define noteCs1 35
#define noteDb1 35
#define noteD1 37
#define noteDs1 39
#define noteEb1 39
#define noteE1 41
#define noteF1 44
#define noteFs1 46
#define noteGb1 46
#define noteG1 49
#define noteGs1 52
#define noteAb1 52
#define noteA1 55
#define noteAs1 58
#define noteBb1 58
#define noteB1 62
#define noteC2 65
#define noteCs2 69
#define noteDb2 69
#define noteD2 73
#define noteDs2 78
#define noteEb2 78
#define noteE2 82
#define noteF2 87
#define noteFs2 93
#define noteGb2 93
#define noteG2 98
#define noteGs2 104
#define noteAb2 104
#define noteA2 110
#define noteAs2 117
#define noteBb2 117
#define noteB2 123
#define noteC3 131
#define noteCs3 139
#define noteDb3 139
#define noteD3 147
#define noteDs3 156
#define noteEb3 156
#define noteE3 165
#define noteF3 175
#define noteFs3 185
#define noteGb3 185
#define noteG3 196
#define noteGs3 208
#define noteAb3 208
#define noteA3 220
#define noteAs3 233
#define noteBb3 233
#define noteB3 247
#define noteC4 262
#define noteCs4 277
#define noteDb4 277
#define noteD4 294
#define noteDs4 311
#define noteEb4 311
#define noteE4 330
#define noteF4 349
#define noteFs4 370
#define noteGb4 370
#define noteG4 392
#define noteGs4 415
#define noteAb4 415
#define noteA4 440
#define noteAs4 466
#define noteBb4 466
#define noteB4 494
#define noteC5 523
#define noteCs5 554
#define noteDb5 554
#define noteD5 587
#define noteDs5 622
#define noteEb5 622
#define noteE5 659
#define noteF5 698
#define noteFs5 740
#define noteGb5 740
#define noteG5 784
#define noteGs5 831
#define noteAb5 831
#define noteA5 880
#define noteAs5 932
#define noteBb5 932
#define noteB5 988
#define noteC6 1047
#define noteCs6 1109
#define noteDb6 1109
#define noteD6 1175
#define noteDs6 1245
#define noteEb6 1245
#define noteE6 1319
#define noteF6 1397
#define noteFs6 1480
#define noteGb6 1480
#define noteG6 1568
#define noteGs6 1661
#define noteAb6 1661
#define noteA6 1760
#define noteAs6 1865
#define noteBb6 1865
#define noteB6 1976
#define noteC7 2093
#define noteCs7 2217
#define noteDb7 2217
#define noteD7 2349
#define noteDs7 2489
#define noteEb7 2489
#define noteE7 2637
#define noteF7 2794
#define noteFs7 2960
#define noteGb7 2960
#define noteG7 3136
#define noteGs7 3322
#define noteAb7 3322
#define noteA7 3520
#define noteAs7 3729
#define noteBb7 3729
#define noteB7 3951
#define noteC8 4186
#define noteCs8 4435
#define noteDb8 4435
#define noteD8 4699
#define noteDs8 4978
#define noteEb8 4978

STEP 2. Include notes.h File in App

Next you need to include the notes.h file in your app code, similar to including a library.

In the code editor, click the tab that contains your main app. Add this code statement at the beginning of your app code:

#include "notes.h"

STEP 3. Add Custom Function to Play Individual Note

A custom function named playNote() will be used to play one musical note at a time. When calling the function, you'll need to include parameters for the note and its duration.

Add the playNote() function after your loop() function:

void playNote(int note, int duration) {
  // variable names for notes and durations defined in "notes.h"
  tone(speaker, note, duration);
  delay(duration);
}

The variable names for the notes and durations are defined in the notes.h file:

• Each note on a piano keyboard is defined in notes.h with a variable name that represents a specific frequency. For example, noteC4 is the variable name for "Middle C", which is defined as having a frequency of 262 Hertz.

• Each duration (whole note, half note, quarter note, etc.) is defined in notes.h with a variable name that represent a specific duration. For example, WN is the variable name for a whole note, which is defined as 4 beats (which will be 800 milliseconds if each beat length is defined as 200 milliseconds).

To play a note, your app code will need to call the playNote() function and list the defined variable names for the specific note and its duration within the parentheses.

For example, to play a "Middle C" whole note:

playNote(noteC4, WN);

STEP 4. Create Custom Function to Play Song Note by Note

To play a song, your app code will need to play each note of the song in order by calling the playNote() function separately for each note (or rest) in the song.

You'll create a custom function named playSong() that will contain all the playNote() statements in sequence for your song.

Add this blank playSong() function after your loop() function:

void playSong() {
  // add code to play each note of song in order using playNote()​
  
}

To play a specific song, you'll need to know how it would be played on a piano one note at a time: i.e., what are the specific notes and their durations (whole note, half note, etc.)

Then you'll have to use the notes.h file to determine which variable names to list for the note (or rest) and its duration. Then you'll need to list a code statement for each note (and rest) to call the playNote() function.

For example, here's what the code inside the playSong() function would need to be in order to play the beginning of the song "Twinkle, Twinkle Little Star":

void playSong() {
  // add code to play each note of song in order using playNote()
  // beginning of "Twinkle, Twinkle Little Star"
  playNote(noteC4, QN);
  playNote(noteC4, QN);

  playNote(noteG4, QN);    
  playNote(noteG4, QN);  

  playNote(noteA4, QN);    
  playNote(noteA4, QN);  

  playNote(noteG4, HN);

  playNote(noteF4, QN);    
  playNote(noteF4, QN);
}

STEP 5. Call Custom Function to Play Song

You can play your song by calling the playSong() function within another function (such as the setup(), loop(), or another custom function) depending on when the song should be played:

playSong();

If you need the song to play faster or slower, you can change the value for the beatLength defined in the notes.h file. By default, beatLength has been set to 200 milliseconds.

• If the song should be played faster, use a lower value for beatLength.

• If the song should be played slower, use a higher value for beatLength.