int readingPin1=A0;
int value1;
float vol1;
int redPin=2;
int yellowPin=3;
int greenPin=4;
int timer=(750);

void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(readingPin1, INPUT);
pinMode(redPin, OUTPUT);
pinMode(yellowPin, OUTPUT);
pinMode(greenPin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
value1=analogRead (readingPin1);
vol1=(5./1023.)*value1;
Serial.println(vol1);

if (vol1==0.0) {
digitalWrite(greenPin, LOW);
digitalWrite(yellowPin, LOW);
digitalWrite(redPin, LOW);
}
if (vol1>0.1 && vol1<2.0) {
digitalWrite(greenPin, HIGH);
digitalWrite(yellowPin, LOW);
digitalWrite(redPin, LOW);
}
if (vol1>2.1 && vol1<3.5) {
digitalWrite(greenPin, LOW);
digitalWrite(yellowPin, HIGH);
digitalWrite(redPin, LOW);
}
if (vol1>3.6 && vol1<=5.0) {
digitalWrite(greenPin, LOW);
digitalWrite(yellowPin, LOW);
digitalWrite(redPin, HIGH);
}

delay(timer);
}