#include <Servo.h>

/*
 * servoPin -> the pin which the servo is connected. Default is pin 7
 * sensorPin -> the pin which the LDR sensor is connected. Default is A0
 * sensorLimit -> the limit value where the servo is activated if the sensor reading falls below than this value.
 */
int servoPin = 7;
int sensorPin = A0;
int sensorLimit = 100;

Servo doorServo;
int sensorReading;

void setup() {
  doorServo.attach(servoPin);
  doorServo.write(0);
  Serial.begin(9600);
}

void loop() {
  sensorReading = analogRead(sensorPin);
  Serial.println(sensorReading);

  if (sensorReading < sensorLimit) {
    doorServo.write(90);
    delay(5000);
    doorServo.write(0);
    delay(5000);
  }
}