int pwmPin = 3;

void setup() {
  pinMode(pwmPin, OUTPUT);
}

void loop() {
  for (int i = 0; i < 360; i++) {
    float rad = i * (PI / 180.0);
    int val = (sin(rad) + 1) * 127.5;  // 0–255
    analogWrite(pwmPin, val);
    delayMicroseconds(500);  // controls frequency
  }
}