[Description]

- Control beat tempo and pitch with two potentiometers

- Use 3 LEDs to indicate different beat tempos 

- Pause beat with FSR

[Components]

- Potentiometer X 2

- Piezo Speaker X 1

- LED X 3 (r, g, b)

- FSR X 1

- Resistor X 4

[Arduino Code]

int sensorPin = 0;  // select the input pin for the sensor
int fsrVal = 0;    // variable to store the value coming from fsr
int pot1Pin = 1;   // select the input pin for the potentiometer 1
int pot2Pin = 2;   // select the input pin for the potentiometer 2
int pot1Val = 0;   // variable to store the value coming from pot 1
int pot2Val = 0;   // variable to store the value coming from pot 2
int led1Pin = 9;   // select the pin for the LED 1
int led2Pin = 10;  // select the pin for the LED 2
int led3Pin = 11;  // select the pin for the LED 3
int speakerPin = 7; // select the pin for speaker
int beat = 200; // set the initial beat tempo
int alt = 1; // alternate pitch for duotone

void setup() {
  pinMode(led1Pin, OUTPUT);
  pinMode(led2Pin, OUTPUT);
  pinMode(led3Pin, OUTPUT);
  pinMode(speakerPin, OUTPUT);
  beginSerial(9600);
  Serial.println("ready");
}

void loop() {
  pot1Val = analogRead(pot1Pin);
  pot2Val = analogRead(pot2Pin);
  fsrVal = analogRead(sensorPin); // read the value from the sensor, 0-1023
 
//  Serial.println(pot1Val);
//  Serial.println(pot2Val);
 
  digitalWrite(speakerPin, LOW);
   
  if (pot1Val < 342) {
    digitalWrite(led1Pin, HIGH);
    digitalWrite(led2Pin, LOW);
    digitalWrite(led3Pin, LOW);
    beat = 10;
  }
  else if ((pot1Val >= 342) && (pot1Val < 684)) {
    digitalWrite(led1Pin, LOW);
    digitalWrite(led2Pin, HIGH);
    digitalWrite(led3Pin, LOW);
    beat = 100;
  }
  else {
    digitalWrite(led1Pin, LOW);
    digitalWrite(led2Pin, LOW);
    digitalWrite(led3Pin, HIGH);
    beat = 200;
  }
  if (fsrVal > 100) {
    for( int i=0; i<beat; i++ ) {
      if( alt >= 0 ) {
        digitalWrite(speakerPin, HIGH);
        delayMicroseconds(pot2Val);
        digitalWrite(speakerPin, LOW);
        delayMicroseconds(pot2Val);
      }
    }
    for( int i=0; i<beat; i++ ) {
      digitalWrite(speakerPin, 0);
      delayMicroseconds(pot2Val);
    }
  }
}

[Video]