#include <Servo.h>

int maxDistanceDoorEmpty = 30;

int flag = 0;
#define trigPin   11
#define echoPin   10
#define servoPin  9

Servo myservo;

long duration;//1000 ms = 1 sec
int distanceCM;

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  myservo.attach(servoPin);
  delay(1000);
  Serial.println("Setup Complete");
}

void loop() {
  messureDistance();
  if (distanceCM > maxDistanceDoorEmpty)
    distanceCM = maxDistanceDoorEmpty;
  distanceCM = map(distanceCM, 0, maxDistanceDoorEmpty, maxDistanceDoorEmpty, 0);
  Serial.print("Distance: ");
  Serial.println(distanceCM);


  if (distanceCM > 10 && distanceCM < 19)
  {
    Serial.println("protect");
    // protect child
    myservo.write(90);
    delay(500);
    flag = 1;
  }
  else if (distanceCM >= 19 || distanceCM < 10) {
    if (flag == 0) {
      // normal people walking

      Serial.println("normal");
      myservo.write(0);
      delay(50);
    }
  }

}//end of loop


void messureDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);//1000 ms = 1 sec
  distanceCM = duration * 0.034 / 2;

}