void setup() {
  pinMode(27, OUTPUT);  // Required for PWM
   // No setup needed for DAC pins
  }

  void loop() {
    // Ramp from 0 to 255
  for (int val = 0; val <= 255; val++) {
    dacWrite(25,  val);      // True analog output (0-3.3V)
    analogWrite(27, val);    // PWM (simulated analog)
    delay(10);
    }
  // Turn off
  dacWrite(25,0);
  analogWrite(27,0);
  delay(250);
}