Week 11 – Musical Device

Concept

I really liked the Ultrasonic Distance Sensor, and I really love the idea of using the outer environment and motion capturing. First, I wanted just to make a device controlled by buttons/potentiometer, but then the idea of using something less obvious came to me. I thought that trying to play sound without touching anything can be really interesting. I decided to use Distance Sensor and Photoresistor for this device.

The musical device is pretty simple: the photoresistor has a threshold of 900 (basically the light that it gets if you point the flashlight right at it), and if it receives light that is higher than this value, it will make the device play. Otherwise it will be silenced. The distance sensor converts the distance into frequency: the farther the object is from it, the lower frequency will be played.

Code

The code is pretty simple. It assigns global variables, has some local variables assigned in the loop() (like the distance and the frequency). Frequency that will be output by the buzzer is determined by the distance. I used distance = duration * 0.0343 / 2; to convert the distance to cm depending on the output of the Ultrasonic device, and then freq = map((int)distance, 5, 200, 800, 200); to map the distance to frequency, so that the distance from 5 to 200 is assigned to frequencies from 800 to 200.

There’s a small block in the beggining of my loop() part to turn off and on the buzzer. It’s made like that so it can change the frequency that it will be outputting.

int lightVal = 0;
bool lightOn = false;

int trigPin = 6;
int echoPin = 5;
long duration;
float distance;
int freq;

int soundPin = 8;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  Serial.println(lightVal);
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  // Calculate distance in cm
  distance = duration * 0.0343 / 2;
  freq = map((int)distance, 5, 200, 800, 200);

  lightVal = analogRead(A0);
  lightOn = lightVal > 950;

  if (lightOn) {
    tone(soundPin, freq);
  } else {
    noTone(8);
  }
}

I was mainly referencing tutorials on Arduino website, like this one for the distance sensor and this one for the photoresistor, to figure out how do I mke them work.

Schematic & Preview

The schematic of the device looks like this (I tried my best to draw it correctly):

This is how it looks in real life:

And this is how it works:

Reflection

I really like how it turned out. My main goal was to use the components of Arduino we haven’t worked in the class with, so I achieved this objective. I also like the fact that I can actually “play” this instrument without even touching it – I think it’s pretty cool.

For further improvement, I believe I can make the device more “usable” because right now pointing the phone right in the middle of bunch of wires doesn’t seem too good. Also, I think I can work with the short delays the device has because now if I flicker the light, it wouldn’t catch it being turned off.