Control of an automatic door

#define BLYNK_PRINT Serial
#include <BlynkSimpleEsp8266.h>
#include <Wire.h>
#include <SimpleTimer.h>
#include "SparkFunHTU21D.h"
#include <SparkFunTSL2561.h>
#include "BlynkBoard_settings.h"
HTU21D thSense;

bool scanI2C(uint8_t address);
 
// Wifi connections

char BlynkAuth[] = "xxxxxxxxx";
char WiFiNetwork[] = "xxxxxxxxxxx";
char WiFiPassword[] = "xxxxxxxxx";

WidgetLCD lcd(V10); //LCD widget on V10
WidgetLED led3(V3); // LED widget in Blynk App on v3
WidgetLED led4(V4); // LED widget in Blynk App on v4
WidgetTerminal terminal(V21);

SimpleTimer timer;


#define DOOR_STATE_VIRTUAL V25
#define DOOR_SWITCH_PIN 13
#define ACTIVATION 12


uint8_t lastSwitchState = 255;
long distancia;
long tiempo;

void setup()
{
  Serial.begin(9600);
  Blynk.begin(BlynkAuth, WiFiNetwork, WiFiPassword); //data to connect
  pinMode(16, OUTPUT); /*pin 16 ultrasonic output*/
  pinMode(15, INPUT); /*pin 15 receive ultrasonic signal*/
  pinMode(12, OUTPUT); //open door
  
  while (Blynk.connect() == false) {
    // Wait until connected
  }

 
}

BLYNK_READ(DOOR_STATE_VIRTUAL)
{
  uint8_t switchState = digitalRead(DOOR_SWITCH_PIN); // Read the door switch pin
  // Pin 16 is pulled low internally. If the switch (and door) is open,
  // pin 16 is LOW. If the switch is closed (door too), pin 16 is HIGH.
  // LOW = open
  // HIGH = closed
  if (switchState && distancia < 10)
  {
    Blynk.virtualWrite(DOOR_STATE_VIRTUAL, "Close"); // Update virtual variable
    digitalWrite(12, HIGH);
  }
  else
  {
    Blynk.virtualWrite(DOOR_STATE_VIRTUAL, "Open");
    digitalWrite(12, LOW);
  } 
  if (lastSwitchState != switchState) // If the state has changed
  {
    if (switchState) // If the switch is closed (door shut)
    {
        
        terminal.println("Door closed." );
        terminal.flush();
     }
    else
    { 
      
        
        terminal.println("Door open.");
        terminal.flush();
      }
     
    }
    lastSwitchState = switchState;
  }  


void loop()
{
  digitalWrite(16,LOW); /* sensor*/
  delayMicroseconds(5);
  digitalWrite(16, HIGH); /* send ultrasonic signal*/
  
  delayMicroseconds(10);
  tiempo=pulseIn(15, HIGH); 
  distancia= int(0.017*tiempo); /*how to calculate the distance*/

  lcd.clear(); //Use it to clear the LCD Widget
  lcd.print(0, 0, "Distance"); // use: (position X: 0-15, position Y: 0-1, "Message you want to print")
  lcd.print(0, 1, distancia);
  lcd.print(10,1, "cm");
  delay(1000);
  Blynk.run();
  timer.run();
}