If you’ve ever wondered how to use your Arduino Uno to play a song or use it as a stand-alone device without the need to connect it to your computer by a cable, this article will discuss the process.

The Arduino UNO R3 is an open source microcontroller board based on the ATmega328, made in Italy. The unit has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. The board contains everything needed to support the microcontroller. To power the unit, it can be connected to your computer with a USB cable.  It can also be powered with an AC-to-DC adapter or, in this case, by a 9 volt battery.

Because the “heart” of the Arduino is a microcontroller (the “brains” of a computer), it requires software code in which to perform functions.  Thus, after purchasing the Arduino UNO, the user should go to the home site, http://www.arduino.cc, to perform the set up. The site also provides royalty-free software code, called sketches, to perform simple operations on the unit, such as blinking lights or, in this case, playing melodies. According to the site, “The open-source Arduino Software (IDE) makes it easy to write code and upload it to the board. It runs on Windows, Mac OS X, and Linux. The environment is written in Java and based on Processing and other open-source software” (www.arduino.cc). The sketches (programs) are typically written in C++.

The Arduino works very much like the Parallax Boe-Bot Robot, discussed in another article on this site.  The code is downloaded, via USB cable, to the unit’s microcontroller and stored in its memory.  A handy reset button on the unit allows you to perform the operation over and over, and the unit will house in memory the last command functions delivered to it.

Using the open source code for playing a melody on the Arduino, I made some modifications in order for the unit to play “Mary Had a Little Lamb.”  The code for that can be found at the end of this article.  To actually hear the music, you will need an 8-ohm speaker and power supply.  To power the unit, you can either connect it to your computer via the USB cable or, as described here,  connect the Arduino unit to a 9-volt battery.  My preference was to have the unit perform as a stand-alone device (i.e., no need to connect it to the computer with the USB cable).  To do so, you will need:

•  One 8-ohm speaker
•  One 9-volt battery snap connector
•  One 9-volt battery

Connect the 8-ohm speaker as follows: red wire to pin 8 and black ground wire to GND on the unit. Next, connect your 9-volt battery wires as follows: red to Vin and black to GND.

You will first need to send the program’s code into the UNO’s memory via your USB cable. Once done, however, you can disconnect the cable, assemble your battery source and speaker, and then hit the reset button.  Your Arduino UNO will happily play “Mary Has a Little Lamb” over and over, with each touch of the reset button.  (If you’re a true glutton for punishment, make a quick modification to the “void loop” command for endless rounds of this timeless classic.)

 

 

/*

Plays a melody: Mary Had a Little Lamb

circuit: * 8-ohm speaker on digital pin 8

Original sketch created 21 Jan 2010

Modified 30 Aug 2011 by Tom Igoe

Revised 5/11/2016 by Kim Craft

The original code is in the public domain and can be found at Arduino.cc.com.

http://www.arduino.cc/en/Tutorial/Tone

*/

#include “pitches.h”

// notes in the melody:

int melody[] = {

NOTE_E4, NOTE_D4, NOTE_C4, NOTE_D4, NOTE_E4, NOTE_E4, NOTE_E4, 0, NOTE_D4, NOTE_D4, NOTE_D4, 0, NOTE_E4, NOTE_G4, NOTE_G4, 0, NOTE_E4, NOTE_D4, NOTE_C4, NOTE_D4, NOTE_E4, NOTE_E4, NOTE_E4, 0, NOTE_D4, NOTE_D4, NOTE_E4, NOTE_D4, NOTE_C4 };

// note durations: 4 = quarter note, 8 = eighth note, etc.:

int noteDurations[] = {

8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 4

};

void setup() {

// iterate over the notes of the melody:

for (int thisNote = 0; thisNote < 30; thisNote++) {

// to calculate the note duration, take one second

// divided by the note type.

//e.g. quarter note = 1000 / 4, eighth note = 1000/8, etc.

int noteDuration = 1000 / noteDurations[thisNote];

tone(8, melody[thisNote], noteDuration);

// to distinguish the notes, set a minimum time between them.

// the note’s duration + 30% seems to work well:

int pauseBetweenNotes = noteDuration * 1.30;

delay(pauseBetweenNotes);

// stop the tone playing:

noTone(8);

}

}

void loop() {

// no need to repeat the melody.

}

// File for Pitches.h

#define NOTE_B0  31

#define NOTE_C1  33

#define NOTE_CS1 35

#define NOTE_D1  37

#define NOTE_DS1 39

#define NOTE_E1  41

#define NOTE_F1  44

#define NOTE_FS1 46

#define NOTE_G1  49

#define NOTE_GS1 52

#define NOTE_A1  55

#define NOTE_AS1 58

#define NOTE_B1  62

#define NOTE_C2  65

#define NOTE_CS2 69

#define NOTE_D2  73

#define NOTE_DS2 78

#define NOTE_E2  82

#define NOTE_F2  87

#define NOTE_FS2 93

#define NOTE_G2  98

#define NOTE_GS2 104

#define NOTE_A2  110

#define NOTE_AS2 117

#define NOTE_B2  123

#define NOTE_C3  131

#define NOTE_CS3 139

#define NOTE_D3  147

#define NOTE_DS3 156

#define NOTE_E3  165

#define NOTE_F3  175

#define NOTE_FS3 185

#define NOTE_G3  196

#define NOTE_GS3 208

#define NOTE_A3  220

#define NOTE_AS3 233

#define NOTE_B3  247

#define NOTE_C4  262

#define NOTE_CS4 277

#define NOTE_D4  294

#define NOTE_DS4 311

#define NOTE_E4  330

#define NOTE_F4  349

#define NOTE_FS4 370

#define NOTE_G4  392

#define NOTE_GS4 415

#define NOTE_A4  440

#define NOTE_AS4 466

#define NOTE_B4  494

#define NOTE_C5  523

#define NOTE_CS5 554

#define NOTE_D5  587

#define NOTE_DS5 622

#define NOTE_E5  659

#define NOTE_F5  698

#define NOTE_FS5 740

#define NOTE_G5  784

#define NOTE_GS5 831

#define NOTE_A5  880

#define NOTE_AS5 932

#define NOTE_B5  988

#define NOTE_C6  1047

#define NOTE_CS6 1109

#define NOTE_D6  1175

#define NOTE_DS6 1245

#define NOTE_E6  1319

#define NOTE_F6  1397

#define NOTE_FS6 1480

#define NOTE_G6  1568

#define NOTE_GS6 1661

#define NOTE_A6  1760

#define NOTE_AS6 1865

#define NOTE_B6  1976

#define NOTE_C7  2093

#define NOTE_CS7 2217

#define NOTE_D7  2349

#define NOTE_DS7 2489

#define NOTE_E7  2637

#define NOTE_F7  2794

#define NOTE_FS7 2960

#define NOTE_G7  3136

#define NOTE_GS7 3322

#define NOTE_A7  3520

#define NOTE_AS7 3729

#define NOTE_B7  3951

#define NOTE_C8  4186

#define NOTE_CS8 4435

#define NOTE_D8  4699

#define NOTE_DS8 4978