#define DAC1 25

void setup() {
  Serial.begin(115200);
}

void loop() { // Generate a Sine wave
  int value; //255= 3.3V 128=1.65V
  
  for(value = 0; value < 256; value +=4 ){
    dacWrite(DAC1, value);
    Serial.println(value);
    delay(10);
  }
  for(value = 255; value > 0; value-- ){
    dacWrite(DAC1, value);
    Serial.println(value);
    delay(10);
  }
}