Lab 2 Arduino Codes and Plots

Here's the Arduino code for our instrument. Basically, the user input from the phtoresistor is read by Arduino and a musical note is assigned. We made eight bins where the input signal can fall into, so it's easier to pick up a note when we play the instrument. However, this can be changed and the musical note (frequency) can be continously varying by simple scaling of the input signal instead of quantizing. We also have a digital input via a mechanical switch, which plays the assigned note only when the switch is closed. As long as the switch is closed, the musical note will be fixed at the frequency when the switch is pressed and the sound will be played continously. Lastly, the sensor read out is transferred back to the computer where a user can see the sensor read out value and the assigned musical note.

Below the code is an example plot for the photoresistor sensor readout.


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int speakerPin = 9;
int sensorValue = 0; // value read from the pot
int outputValue = 0; // value output to the PWM (analog out)
int switchValue = 0; // switch to turn on or off the sound
const int analogInPin = 1; // Analog input pin that the potentiometer is attached to
const int digitalInPin = 22;// Digital input pin that the switch is connected to


int length = 15; // the number of notes



void setup() {
// initialize serial communications at 9600 bps:
Serial.begin(9600);
pinMode(speakerPin, OUTPUT);
}

void playTone(int tone) {
for (long i = 0; i < 1;) {
digitalWrite(speakerPin, HIGH);
delayMicroseconds(tone);
digitalWrite(speakerPin, LOW);
delayMicroseconds(tone);
if (digitalRead(digitalInPin) == 1){
i=1;
}
}
}

void playNote(char note) {
char names[] = { 'c', 'd', 'e', 'f', 'g', 'a', 'b', 'C' };
int tones[] = { 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956 };

// play the tone corresponding to the note name
for (int i = 0; i < 8; i++) {
if (names[i] == note) {
playTone(tones[i]);
}
}
}



void loop() {
for (int i = 0; i < length; i++) {
sensorValue = analogRead(analogInPin);

// map it to the range of the analog out:
char note;
if (sensorValue < 600) {
note = 'C';
}
else if (sensorValue >=600 & sensorValue < 638) {
note = 'C';
}
else if (sensorValue >=638 & sensorValue < 676) {
note = 'b';
}
else if (sensorValue >=676 & sensorValue < 714) {
note = 'a';
}
else if (sensorValue >=714 & sensorValue < 752) {
note = 'g';
}
else if (sensorValue >=752 & sensorValue < 790) {
note = 'f';
}
else if (sensorValue >=790 & sensorValue < 828) {
note = 'e';
}
else if (sensorValue >=828 & sensorValue < 866) {
note = 'd';
}
else if (sensorValue >=866 & sensorValue < 900) {
note = 'c';
}
else if (sensorValue > 900) {
note = 'c';
}
if(digitalRead(digitalInPin) == 0) {
playNote(note);
}


Serial.print("sensor = " );
Serial.print(sensorValue);
Serial.print("\t output = ");
Serial.print(note);
Serial.print("\t switch = ");
Serial.println(digitalRead(digitalInPin));
}

}
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