Arrays

Variables are a great way to store one value that you can use later on in your program. But what if you need to store multiple values at the same time, like keeping score in a multi-player video game? This is where arrays are useful. One array can hold as many values as you decide to set!

One of the best ways to think of arrays is like a row of boxes. Each box, which stores a value, is called an element. Keep in mind that computers start counting at 0, so boxes 0-7, like we have below, are actually called myArray[8] when they’re together.

One more important thing to remember: the data that’s in an array has to be the same type. You cannot have an array with values like [apple, 78, J, CoDrone], but you can have an array with values like [78, -56, 324, 760452].

If you’re lazy, you’ll love arrays since you don’t need to name every single element! You can just group all of the elements under one title (we called ours myArray) and number them from 0 to whatever your last element is.

In this example, we wanted to store 8 different integers: 1, 7, 15, -23, -92, 0, 5, and 57. All of them would start out with myArray[] and have their element number next to it. If we wanted to recall a specific element’s value later on in the program, we would just need to use the element’s number. For example, if we wanted to recall the value 1, we could write myArray[0], since 1 is represented by element 0.

Just like variables, arrays need to be initialized at the beginning of your program before they can be used. Most arrays follow this format:

data type ArrayName[Array Size]

Test this code out, and make sure your serial monitor is open!

int newArray[5] = {10, 15, 22, 9, -5}; 

void setup() { 
    Serial.begin(9600);
} 

void loop() {  
    for ( int i = 0; i <= 4 ; i++ ) { 
        Serial.println(newArray[i]); 
    }
}

Arrays can be used for anything, but for this lesson you’re going to use arrays to make some music on your CoDrone’s remote control!

The first thing you need to do in Arduino is set up the CoDrone library. Next, you need to make an array (we called ours melody) and set your notes up inside. Quick tip about music: a set of notes are in a scale, and scales go up or down in pitch. Usually, there are eight notes in one scale. For this program, you’re only using eight notes.

You need to make one more array for how long your notes will be, or the duration. Our array is called noteDurations. The 0th element, 1, is about 1 second long, the 3rd element in this array, 4, is about 0.25 seconds long, and the 7th element, 8, is about 0.125 seconds long.

#include<CoDrone.h>

int melody[] = {
  NOTE_C3, NOTE_D3, NOTE_E3, NOTE_F3, NOTE_G3, NOTE_A3, NOTE_B3, NOTE_C4
};

int noteDurations[] = {
  1, 2, 3, 4, 5, 6, 7, 8
};

You can use a for loop to access your array and have your buzzers play a scale! In void setup(), write a for loop that starts a variable (we called ours thisNote) at 0, and when the variable is less than or equal to 7, a value of 1 is added. As long as the variable’s value is between 0 and 7, the corresponding note will play for 0.25 seconds.

We added a 500-millisecond delay so there’s enough space in between this scale and what’s coming next, but you don’t absolutely have to add this.

void setup() {
for (int thisNote = 0; thisNote<=7; thisNote++){
  CoDrone.Buzz(melody[thisNote], noteDurations[3]);
}
delay(500);

Use another for loop to play your scale, but this time, write it so that your variable starts at 7. When the variable is greater than or equal to 0, a value of 1 is subtracted. As long as the variable’s value is between 7 and 0, the corresponding note will play for 0.25 seconds.

Again, we added a delay of 500 milliseconds, but you still don’t absolutely have to do this.

for (int thisNote = 7; thisNote>=0; thisNote--){
  CoDrone.Buzz(melody[thisNote], noteDurations[3]);
}
delay(500);

As long as the elements in your array are notes, you can access them to play songs! To start, make sure each commands starts with the CoDrone.Buzz function.

Since you have two arrays — one for the notes and one for the duration — you need to use them both between one set of parentheses and separate them with a comma. The first element should be the note and the second element should be the duration.

If you have this in your code:

CoDrone.Buzz(melody[0],noteDurations[2]);
delay(50);
CoDrone.Buzz(melody[0],noteDurations[2]);
CoDrone.Buzz(melody[1],noteDurations[1]);
CoDrone.Buzz(melody[0],noteDurations[1]);
CoDrone.Buzz(melody[3],noteDurations[1]);
CoDrone.Buzz(melody[2],noteDurations[0]);

It will look like this without the array:

CoDrone.Buzz(NOTE_C3,3);
delay(50);
CoDrone.Buzz(NOTE_C3,3);
CoDrone.Buzz(NOTE_D3,2);
CoDrone.Buzz(NOTE_C3,2);
CoDrone.Buzz(NOTE_F3,2);
CoDrone.Buzz(NOTE_E3,1);

This is what your final code should look like:

#include<CoDrone.h>

int melody[] = {
  NOTE_C3, NOTE_D3, NOTE_E3, NOTE_F3, NOTE_G3, NOTE_A3, NOTE_B3, NOTE_C4
};

int noteDurations[] = {
  1, 2, 3, 4, 5, 6, 7, 8
};

void setup() {
for (int thisNote = 0; thisNote<=7; thisNote++){
 CoDrone.Buzz(melody[thisNote], noteDurations[3]);
}
delay(500);

for (int thisNote = 7; thisNote>=0; thisNote--){
  CoDrone.Buzz(melody[thisNote], noteDurations[3]);
}
delay(500);

CoDrone.Buzz(melody[0],noteDurations[2]);
delay(50);
CoDrone.Buzz(melody[0],noteDurations[2]);
CoDrone.Buzz(melody[1],noteDurations[1]);
CoDrone.Buzz(melody[0],noteDurations[1]);
CoDrone.Buzz(melody[3],noteDurations[1]);
CoDrone.Buzz(melody[2],noteDurations[0]);
}

void loop(){
}

Challenge: Make Some Noise!

Use notes in an array to have your buzzers play a song!

Rules:

• Your program must use at least one array that has notes in it.
• Your song should be at least 5 seconds long.

Bonus: if you can read music, use that to help you program your favorite song!