int trig = 27;
int echo = 26;
int distance ;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  pinMode(17, OUTPUT);
  pinMode(18, OUTPUT);
  pinMode(21, OUTPUT);
}

void loop() {
  digitalWrite(trig, HIGH);
  delay(1000);
  digitalWrite(trig, LOW);
  int reading =(pulseIn(echo,HIGH));
distance = (reading*0.034/2);
Serial.println("ok , recieved");
Serial.println(distance);

if(distance>300)
{
  digitalWrite(18, HIGH);
  digitalWrite(17, LOW);
  digitalWrite(21, LOW);
}

else if(distance>200)
{
  digitalWrite(21, HIGH);
  digitalWrite(18, LOW);
  digitalWrite(17, LOW);
}
else if (distance>100)
{
  digitalWrite(17, HIGH);
  digitalWrite(18, LOW);
  digitalWrite(21, LOW);
}

  // put your main code here, to run repeatedly:
  delay(10); // this speeds up the simulation
}