#define TRIGGER_PIN 18
#define ECHO_PIN 19
#define led 21
float measureDistance()
{
digitalWrite(TRIGGER_PIN, LOW);
delayMicroseconds(2);
digitalWrite(TRIGGER_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIGGER_PIN, LOW);

long duration = pulseIn(ECHO_PIN, HIGH);
float distance = duration*0.034/2;
return distance;
}

void setup() {
  pinMode(led, OUTPUT);
  pinMode(TRIGGER_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
}

void loop() 
{
  float distance = measureDistance();
  Serial.print("Distance : ");
  Serial.print(distance);
  Serial.println(" cm ");
  delay(1000);
if (distance > 150)
{
  digitalWrite(led, HIGH);
  delay(1000);
}
else
{
  digitalWrite(led, LOW);
  delay(1000);
}

}