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Digital-to-Analog Converter (DAC)

The Arduino Uno R4 WiFi comes equipped with a built-in DAC (Digital-to-Analog Converter) feature. A DAC is crucial for converting digital signals into their analog counterparts, a functionality that’s particularly vital in applications like audio processing, analog signal generation, and other scenarios requiring precise analog output.

The DAC on the Uno R4 WiFi boasts up to 12-bit resolution, delivering true analog output capabilities that outperform those of PWM pins.

Play Music with DAC

Circuit Diagram

Upload the Code

Open the 07-dac.ino file located at elite-explorer-kit-main\r4_new_feature\07-dac, or paste the following code into your Arduino IDE.

Note

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

pitches.h

/*****************
Public Constants
*****************/
#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 49

07-dac.ino

/*
  This code is aimed at producing a melody through a DAC (Digital to 
  Analog Converter) on pin A0 of an Arduino Uno R4 board using the 
  analogWave library. The melody and rhythm are defined within an 
  array where each note is followed by its duration, based on a 
  specified tempo. The analogWave object is initialized to generate 
  sine waves, and the melody is played within the main loop. Each 
  note is played for 85% of its duration, followed by a pause of 15% 
  of the note's duration before proceeding to the next note. The 
  melody repeats indefinitely with a one-second pause between 
  repetitions.

  Board: Arduino Uno R4 
*/


#include "analogWave.h"
#include "pitches.h"

// Melody and rhythm defined as an array
// Each note is followed by its duration (4 = quarter note, 8 = eighth note, etc.)
int melody[] = {
  // Super Mario Bros theme
  // Score available at https://musescore.com/user/2123/scores/2145
  // Theme by Koji Kondo
  NOTE_E5,8, NOTE_E5,8, REST,8, NOTE_E5,8, REST,8, NOTE_C5,8, NOTE_E5,8, //1
  NOTE_G5,4, REST,4, NOTE_G4,8, REST,4, 
  NOTE_C5,-4, NOTE_G4,8, REST,4, NOTE_E4,-4, // 3
  NOTE_A4,4, NOTE_B4,4, NOTE_AS4,8, NOTE_A4,4,
  NOTE_G4,-8, NOTE_E5,-8, NOTE_G5,-8, NOTE_A5,4, NOTE_F5,8, NOTE_G5,8,
  REST,8, NOTE_E5,4,NOTE_C5,8, NOTE_D5,8, NOTE_B4,-4,
};

analogWave wave(DAC);  // Initialize the analogWave object for DAC(A0)

int noteCounter = 0;                  // Index to keep track of which note is being played
int tempo = 200;                      // Set the tempo in BPM (Beats Per Minute)
int wholenote = (60000 * 4) / tempo;  // Calculate the duration of a whole note in ms
int divider = 0, noteDuration = 0;    // Variables to hold note duration

void setup() {
  wave.sine(10);  // Initialize the sine wave generator with a frequency of 10 Hz
}

void loop() {
  // Calculate the duration of the current note
  divider = melody[noteCounter + 1];
  if (divider > 0) {
    // For regular notes
    noteDuration = wholenote / divider;
  } else if (divider < 0) {
    // For dotted notes (duration increased by 50%)
    noteDuration = wholenote / abs(divider);
    noteDuration *= 1.5;  // Increase the duration by 50% for dotted notes
  }

  // Play the note
  wave.freq(melody[noteCounter]);
  delay(noteDuration * 0.85);  // Play the note for 85% of its duration
  wave.stop();

  // Pause between notes
  delay(noteDuration * 0.15);  // Pause for 15% of the note duration

  // Increment the note counter by 2 (because each note is followed by its duration)
  noteCounter += 2;

  // Reset the counter when reaching the end of the melody
  int totalNotes = sizeof(melody) / sizeof(melody[0]);
  noteCounter = noteCounter % totalNotes;

  // Add a delay between repetitions of the melody
  if (noteCounter == 0) {
    delay(1000);
  }
}

This project leverages the Arduino and DAC (Digital-to-Analog Converter) to play the iconic Super Mario Bros theme song. It utilizes a library called analogWave for sine wave generation and another library, pitches.h, for defining note frequencies.

• melody[]: This array contains the notes to be played along with their durations. Notes are represented by predefined pitches (e.g., NOTE_E5), and durations are represented in terms of beats (e.g., 4 signifies a quarter note). You can try composing your own melody by changing the notes and durations in the melody[] array. If you are interested, there is a repository on GitHub (robsoncouto/arduino-songs) that provides Arduino code for playing different songs. Although their approach may be different from this project, you can refer to their notes and durations. (Simply replace the melody[] in the corresponding track with the code in this project.)

• tempo : The tempo for this project is set at 200 BPM (Beats Per Minute), which is used to calculate the duration of each note. Modifying this value will change the speed of the song’s performance.

• Sine Wave Generator: The analogWave library’s sine function initializes a 10 Hz sine wave generator, which is used for outputting the notes via DAC.

• Note Duration: Based on the set tempo and the beat count for each note, the duration for each note is calculated.

• Play and Pause: Each note plays for 85% of its calculated duration, followed by a 15% pause to distinguish between notes.

• Loop: Upon completing the melody, the code automatically resets and starts playing again.

This is an example that demonstrates how to use Arduino and external hardware (DAC) to generate music. It also shows how to use arrays and loops to simplify the logic of music playback.

Reference

• Arduino UNO R4 WiFi Digital-to-Analog Converter (DAC)