Laser Harp

This is a musical instrument that uses MIDI communication, lasers, and photoresistors to generate sounds.

Jun 17, 2021

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2 respects

Components and supplies

Audio / Video Cable Assembly, MIDI

Photo resistor

Sound card

DIN Audio / Video Connector, 5 Contacts

Arduino UNO

Laser Diode, Visible

Tools and machines

Soldering iron (generic)

Apps and platforms

Garage Band

Project description

Code

Laser Harp CODE

arduino

1#include <MIDI.h>
2MIDI_CREATE_DEFAULT_INSTANCE();
3
4//Photoresistor  connection pin
5int LDR1 = A0;
6int LDR2 = A1;
7int LDR3 = A2;
8int LDR4  = A3;
9int LDR5 = A4;
10
11//Tone selection
12int NOTA1 = 72;
13int NOTA2  = 74;
14int NOTA3 = 76;
15int NOTA4 = 79;
16int NOTA5 = 81;
17
18void setup()  {
19  Serial.begin(9600);
20  
21  MIDI.begin(MIDI_CHANNEL_OFF);
22    
23  pinMode(LDR1, INPUT);
24  pinMode(LDR2, INPUT);
25  pinMode(LDR3, INPUT);
26  pinMode(LDR4, INPUT);
27  pinMode(LDR5, INPUT);
28}
29
30void loop() {
31  int SLDR1 = analogRead(LDR1);
32  int SLDR2 = analogRead(LDR2);
33  int SLDR3  = analogRead(LDR3);
34  int SLDR4 = analogRead(LDR4);
35  int SLDR5 = analogRead(LDR5);
36
37
38   if (SLDR1 <= 400){//if the photoresistor detects less light it plays a note
39    MIDI.sendNoteOn(NOTA1,120,1);
40   }
41   else{//if the photoresistor detects  more light it stops the note
42    MIDI.sendNoteOff(NOTA1,0,1);
43   }
44
45   if (SLDR2 <= 400){
46    MIDI.sendNoteOn(NOTA2,120,1);
47   }
48   else{
49    MIDI.sendNoteOff(NOTA2,0,1);
50   }
51      if (SLDR3 <= 400){
52    MIDI.sendNoteOn(NOTA3,120,1);
53   }
54   else{
55    MIDI.sendNoteOff(NOTA3,0,1);
56   }
57
58   if (SLDR4  <= 400){
59    MIDI.sendNoteOn(NOTA4,120,1);
60   }
61   else{
62    MIDI.sendNoteOff(NOTA4,0,1);
63   }
64      if (SLDR5 <= 400){
65    MIDI.sendNoteOn(NOTA5,120,1);
66   }
67   else{
68    MIDI.sendNoteOff(NOTA5,0,1);
69   }
70}

#include <MIDI.h>
MIDI_CREATE_DEFAULT_INSTANCE();

//Photoresistor  connection pin
int LDR1 = A0;
int LDR2 = A1;
int LDR3 = A2;
int LDR4  = A3;
int LDR5 = A4;

//Tone selection
int NOTA1 = 72;
int NOTA2  = 74;
int NOTA3 = 76;
int NOTA4 = 79;
int NOTA5 = 81;

void setup()  {
  Serial.begin(9600);
  
  MIDI.begin(MIDI_CHANNEL_OFF);
    
  pinMode(LDR1, INPUT);
  pinMode(LDR2, INPUT);
  pinMode(LDR3, INPUT);
  pinMode(LDR4, INPUT);
  pinMode(LDR5, INPUT);
}

void loop() {
  int SLDR1 = analogRead(LDR1);
  int SLDR2 = analogRead(LDR2);
  int SLDR3  = analogRead(LDR3);
  int SLDR4 = analogRead(LDR4);
  int SLDR5 = analogRead(LDR5);


   if (SLDR1 <= 400){//if the photoresistor detects less light it plays a note
    MIDI.sendNoteOn(NOTA1,120,1);
   }
   else{//if the photoresistor detects  more light it stops the note
    MIDI.sendNoteOff(NOTA1,0,1);
   }

   if (SLDR2 <= 400){
    MIDI.sendNoteOn(NOTA2,120,1);
   }
   else{
    MIDI.sendNoteOff(NOTA2,0,1);
   }
      if (SLDR3 <= 400){
    MIDI.sendNoteOn(NOTA3,120,1);
   }
   else{
    MIDI.sendNoteOff(NOTA3,0,1);
   }

   if (SLDR4  <= 400){
    MIDI.sendNoteOn(NOTA4,120,1);
   }
   else{
    MIDI.sendNoteOff(NOTA4,0,1);
   }
      if (SLDR5 <= 400){
    MIDI.sendNoteOn(NOTA5,120,1);
   }
   else{
    MIDI.sendNoteOff(NOTA5,0,1);
   }
}

Downloadable files

MIDI to Arduino connection

LDR circuit

Laser Harp full schematic

Powers the laser modules. Make a resistive divider with the photoresistors and 1KΩ resistors and connect them to the analog pins of Arduino. Connect the midi port on the Arduino TX pin with a 220Ω resistor to protect the sound card (VERY IMPORTANT).

Laser Harp full schematic

MIDI to Arduino connection

Laser Harp full schematic

LDR circuit

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giovanni_canone

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