int read_pin = A0;
int raw_data = 0;
float voltage = 0;

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

void loop() {
  // put your main code here, to run repeatedly:
  delay(100);
  raw_data = analogRead(read_pin);
  Serial.print(raw_data);
  Serial.print(", ");
  Serial.print(raw_data * 5/1023.0);
  voltage = raw_data/1023.0*5;
  Serial.print(", ");
  Serial.println(voltage);
}