void setup(){
  analogWrite(10, 38); //Output 0.6V(Duty cycle:15%) from D10
  delay(10);
  analogReference(EXTERNAL); //Set peak voltage of analog input

  Serial.begin(115200); //Start serial connection
  Serial.println("Setups are done. It will start to measure."); //Boot message

  analogWrite(9, 38); //Constant Current output start
}

void loop(){
  float volt = analogRead(A0) * 0.6 / 1023; //Read voltage and save on "volt"
  //V=RI ⇔ R=1000V(CRD : 1mA)
  float ohm = volt * 1000; //Calculate resistance
  
  Serial.print("Resistance : ");
  Serial.print(ohm);
  Serial.println("Ω");
}