#define echoPin 9 // attach pin D2 Arduino to pin Echo of HC-SR04
#define trigPin 8 //attach pin D3 Arduino to pin Trig of HC-SR04
#define LED 7 //attach pin D3 Arduino to pin Trig of HC-SR04
#define OLED 6  
#define YLED 5  
#define BLED 4  
#define GLED 3  


// defines variables
long duration; // variable for the duration of sound wave travel
int distance; // variable for the distance measurement

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; // Speed of sound wave divided by 2 (go and back)
 
  // Displays the distance on the Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

//Custom Code 

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


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

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

if (distance <=400){
  digitalWrite(GLED, HIGH);
}
else{
 digitalWrite(GLED, LOW); 
}


}