float floatMap(float x, float in_min, float in_max, float out_min, float out_max){
  return (x-in_min) * (out_max - out_min)/ (in_max - in_min) + out_max;
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  
}

void loop() {
 int analogValue = analogRead(12);

 float voltage = floatMap(analogValue, 0, 4095, 0, 3.3);

 Serial.print("Analog: ");
 Serial.print(analogValue);
 Serial.print(" Voltage :");
 Serial.println(voltage*1000);

 delay(1000);

}