Keyboard/Theremin – Distance Measuring Sensor

introduction

When we were still working with processing, I made a keyboard simulator for one of my assignments. However, it wasn’t very practical. It was controlled with the arrow keys and space bar, meaning it took some time to travel between notes. So, for this week’s assignment, I decided to redo it with Arduino and a distance measuring sensor. A note will play based on the distance of an object/your hand from the sensor.

The sensor resulted in some noise, so I marked the exact spot where each note would sound decent, using lines on some papers, as shown here:

circuit And functionality

This is how the wiring goes:

As mentioned, I used a distance measuring sensor to (obviously) measure the distance of some object from the sensor. The range of the distance is limited (using constrain and map).
I also used a button. This is used to activate the sound when pressed. This is useful to control the length of a note since the note stops playing when the button is not pressed.
Finally, there is a buzzer which produces the sounds. It is only triggered when the button is pressed and when the object is within the distance range. It plays a specific note based on the distance from the sensor.

difficulties

The wiring for this assignment was quite straightforward. My main struggle this week was with the code. Even though it is brief, it took me a lot of time, trial, and error to figure out how to:

• • • • initialize the sensor
      • try to eliminate the noise as much as possible with the distance.

Even though I tried my best to eliminate the noise, I wasn’t able to fully do that, that’s why I marked the spot where the note would play clearly with a line for each note.

Code

#include "pitches.h"

int button = 2;
int sensorEcho = 3;
int sensorTrig = 4;
int buzzer = 5;
long distance;
long duration;
int buttonState;

int notes[8] = {NOTE_C4, NOTE_D4, NOTE_E4, NOTE_F4, NOTE_G4, NOTE_A4, NOTE_B4, NOTE_C5};

void setup() {
  // put your setup code here, to run once:
  
  Serial.begin(9600);
  pinMode(sensorEcho,INPUT);
  pinMode(sensorTrig,OUTPUT);
  pinMode(button, INPUT);
  pinMode(buzzer, OUTPUT);
  
}

void loop() {
  // put your main code here, to run repeatedly:
  buttonState = digitalRead(button);
  
  //initializing the distance measuring sensor
  digitalWrite(sensorTrig,HIGH);
  delayMicroseconds(1000);
  digitalWrite(sensorTrig, LOW);
  duration=pulseIn(sensorEcho, HIGH); 
  distance =constrain((duration/2)/29.1 ,4,81); //getting the distance value
  delay(10);
   
////  Serial.println(temp);
//
//  Serial.print(duration);
//  Serial.print(" , ");
//  Serial.println(distance);

  //if the button is not pressed or you are outside of the distance range
  if (buttonState == LOW || distance < 3 || distance > 80) 
  {
    noTone(buzzer); //the buzzer will not play anything
  }
  //if the button is pressed and you are within the distance range
  else if (buttonState == HIGH) 
  {
    int note = map(distance, 4, 81, 0, 8); //determine which note to play based on the distance
    tone(buzzer, notes[note]); //play the note
  }
}

//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 4978

final outcome

This is the final outcome.
In the end, I tried (TRIED) to demonstrate how this works by playing a small snippet of a song. However, I’m pretty sure the song is only clear to me because I already know what it is (haha), let me know if you can tell what song it is.