#define echoPin 9//attach pin D2 Arduino to pin Echo of HC-SR04
#define trigPin 8//attach pin D3 Arduino to pin trig Echo of HC-SR04
#define LED 7//attach pin D3 Arduino t pin Trig of HC-SR04
#define GLED 4//yellow
#define BLED 3//blue
#define YLED 2//yellow
#define OLED 5//orange
long duration;
int distance;



void setup() {
  pinMode(trigPin, OUTPUT);//Sets the trigPin as an OUTPUT
pinMode(echoPin, INPUT);//Sets the echoPin as an INPUT
Serial.begin(9600);//Serial Communication is starting with 9600 of baudrate speed
Serial.println("Ultrasonic Sensor HC-SR04 Test");//print some text in Serial Monitor
Serial.println("With Arduino UNO R3");
}
void loop() {
// Clears the trigPin condition
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
//Sets the trigPin HIGH (ACTIVE) for 10 microseconds
digitalWrite(trigPin, HIGH);
digitalWrite(LED, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
digitalWrite(LED, LOW);
//Reads the echoPin, returns the sound wave travel time in microseconds
duration = pulseIn(echoPin, HIGH);
//Calculating the distance
distance = duration * 0.034 / 2;
//Displays the distance on the Serial Monitor
Serial.print("Distance:");
Serial.print(distance);
Serial.println(" cm");

//OLED
 if(distance <=100){
  digitalWrite(OLED, HIGH);
}
 else{
  digitalWrite(OLED, LOW);

}

//YLED
if(distance <=200){
  digitalWrite(YLED, HIGH);
}
else{
  digitalWrite(YLED, LOW);

}
//BLED
if(distance <=300){
  digitalWrite(BLED, HIGH);
}
else{
  digitalWrite(BLED, LOW);

}
//GLED
if(distance <=394){
  digitalWrite(GLED, HIGH);
}
else{
  digitalWrite(GLED, LOW);

}
}