Arduino serial DC Voltmeter.

Dc_Voltimeter.ino

/*
DC Voltmeter 
Based on Arduino DVM based on voltage divider concept
T.K.Hareendran
*/


int voltsInput = 0;
float vout = 0.0;
float vin = 0.0;
float R1 = 100000.0; // resistance of R1 (100K)
float R2 = 10000.0; // resistance of R2 (10K)
int value = 0;
void setup(){
   pinMode(voltsInput, INPUT);
   Serial.begin(9600);
   Serial.println("DC VOLTMETER");
}
void loop(){
  
   // read the value at analog input
   value = analogRead(voltsInput);
   vout = (value * 5.0) / 1024.0; // see text
   vin = vout / (R2/(R1+R2)); 
   if (vin<0.09) {
        vin=0.0;//statement to quash undesired reading !
        } 
  Serial.println("INPUT V= ");
  Serial.println(vin);
  delay(1000);
}