Ultrasonic Theremin

1
2//In this project we create a theremin with two ultrasonic sensors,  one for volume and another for tone. We use the digital potentiometer X9C103P.
3//  Two ultrasonic sensors are used to create a theremin. One sensor controls volume,  the other controls frequency.
4// This project is an iteration on a previous project  I found for a theremin. The previous project had library conflicts (two libraries  used the same timer) and used a different type of poteniometer. I have also added  some other small features.
5// Project which provided original inspiration: https://create.arduino.cc/projecthub/opus9/theremino-f72d32
6//  Resource on controlling similar potentiometer using SPI protocol, provides example  code and electrical setup: http://www.learningaboutelectronics.com/Articles/MCP4131-digital-potentiometer-circuit.php
7
8  *
9 */
10//NewTone is used to avoid the timer incompatibiliy of Tone with NewPing.  
11#include <NewTone.h>
12#include <NewPing.h> 
13#include <SPI.h>
14#define  MIN_DISTANCE 35 
15
16NewPing sonar(5, 6, 35); //sonar(pin, pin, distance), this  controls volume 
17
18// name pins for sensors and the potentiometer
19
20
21//  For SPI
22byte address = 0x00;
23int CS= 10;
24
25int echo = 3;                            
26int  trigger = 4;
27
28int distance;
29int PotValue;
30
31unsigned long TimeResponse;
32float  distance2;
33float tone1;
34
35void setup() {
36// set all the pins 
37Serial.begin(9600);  
38pinMode(trigger, OUTPUT); //Tone sensor                    
39pinMode(echo,  INPUT); //Tone sensor    
40pinMode (CS, OUTPUT);
41SPI.begin();
42
43//This  has the speaker emit a start up sound from Low to High to Low
44digitalPotWrite(255);
45for  (int i = 50; i <= 400; i++)
46{
47pinMode(9, OUTPUT);
48  NewTone(9,i);
49  delay(10);
50}
51delay(500);
52for  (int i = 400; i >= 50; i--)
53{
54pinMode(9, OUTPUT);
55  NewTone(9,i);
56  delay(10);
57}
58
59  
60}
61
62void loop() {
63  
64  digitalWrite(trigger, HIGH);           
65  delayMicroseconds(10);   // creates a 10 microsecond pulse                      
66  digitalWrite(trigger, LOW);                   
67  TimeResponse = pulseIn(echo,  HIGH);  // records how long it took to receive echo of the pulse
68  distance2  = TimeResponse/58;  //calculates distance in centimeters
69
70
71  if (distance2  < MIN_DISTANCE) { 
72  //Conversion of distance into a value for a sound 
73  tone1  = 50.0*pow(2,(distance2/12.0));  //calculate frequency, range of about 50-360 Hz
74  pinMode(9, OUTPUT);
75  NewTone(9,tone1);
76    }
77  else {
78    pinMode(9,  OUTPUT); // This sets the sound to a high pitched noise when no distance is detected
79  NewTone(9,400);
80  }
81 
82distance = sonar.ping_cm(); //Uses the library  NewPing to calculate distance
83
84//distance is converted to Potentiometer relevant  values
85
86int PotValue = map(distance, 0, 35, 240, 255); // I only use a range  of resistance which is very low otherwise the speaker is too quiet becuae it is  only a 4 ohm speaker
87
88if (distance == 0) // sets volume to max when no hand  is detected or if hand is too far away
89{
90  PotValue = 255;
91}
92
93digitalPotWrite(PotValue);
94delay(10);
95
96  
97}
98
99int digitalPotWrite(int value)
100{
101digitalWrite(CS, LOW); //This  uses SPI protocol to communicate with the potentiometer and sets the resistance
102SPI.transfer(address);
103SPI.transfer(value);
104digitalWrite(CS,  HIGH);
105
106
107}
108