// UltraSonic _proximity_sensor
// https://forum.arduino.cc/t/help-me-with-my-code/1376382

const int buttonPin = 4;
const int ledPin = 2;
const int triggerPin = 7;
const int echoPin = 8;
// bool valid = false;

void setup() {
  Serial.begin(115200);
  pinMode(triggerPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);

}

void loop() {
  
  long duration, cm, inches;

  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);

  duration = pulseIn(echoPin, HIGH);

  cm = microsecondsToCentimeters(duration);
  Serial.print(cm);
  Serial.println("cm");

  // if(cm < 100){
  //   valid = true;
  // }
  // else{
  //   valid = false;
  // }

  if(cm < 100 && digitalRead(buttonPin) == LOW){
    digitalWrite(ledPin, HIGH);
  }
  else{
    digitalWrite(ledPin, LOW);
  }


}

long microsecondsToCentimeters(long microseconds){
  return microseconds / 29 / 2;
}