int DAC_pins[] = {9, 10, 11, 12}; //pins which control the DAC from LSb to MSb
int DAC_size = 4;


void DAC_set(int a){
  for(int i = 0; i < DAC_size; i++){
    digitalWrite(DAC_pins[i], a & 1<<i);
  }
}

void setup() {
  Serial.begin(9600);  

  for(int i = 0; i < DAC_size; i++){
    pinMode(DAC_pins[i], OUTPUT);
  }

  for(int i = 0; i < 1<<DAC_size; i++){
    DAC_set(i);
    delay(10);
    Serial.print(i);Serial.print(" - ");Serial.println(analogRead((A0)));
  }

}

void loop() {
  // put your main code here, to run repeatedly:

}