int i=0;
float theta =0.0;
float signal =0.0;
float signal_in =0.0;
int p=5;

void setup() {
  Serial.begin(9600);
  pinMode(3, OUTPUT);  // sets the pin as signal output
  pinMode(A0, INPUT);  // sets the pin as analog signal input
}

void loop() {

  theta = (i/100.0)*TWO_PI;
  signal = sin(theta);
  analogWrite(3, signal);

  Serial.println(signal);

  if(i<=100) {
    if(i==100) {
      i=0;
    }
    else {
      i++;
    }
  }
  signal_in=analogRead(A0);
  delay(p*10);

}