/*
1022041063_Ultrasonic Distance Sensor

name : Shruti Vinod Shinde 

turn on LED on when an object is within 100cm range.
*/

#define ECHO_PIN 2
#define TRIG_PIN 3

void setup() {
   Serial. begin(115200);
   pinMode(LED_BUILTIN,OUTPUT);
   pinMode(TRIG_PIN, OUTPUT);
   pinMode(ECHO_PIN, INPUT);
}

float readDistanceCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN,HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN,LOW);
  int duration= pulseIn(ECHO_PIN,HIGH);
  return duration * 0.034/2;

}

void loop(){
  float distance= readDistanceCM();

bool isNearby = distance <100;
digitalWrite(LED_BUILTIN, isNearby);

Serial.print("measured distance:");
 Serial.println(readDistanceCM());

 delay(100);
}