Smart Mask

#include <LiquidCrystal.h>
int sensorvalue = 0;
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

long readUltrasonicDistance(int triggerPin, int echoPin)
{
	pinMode(triggerPin, OUTPUT); // Clear the trigger
	digitalWrite(triggerPin, LOW);
	delayMicroseconds(2);
	// Sets the trigger pin to HIGH state for 10 microseconds
	digitalWrite(triggerPin, HIGH);
	delayMicroseconds(10);
	digitalWrite(triggerPin, LOW);
	pinMode(echoPin, INPUT);
	// Reads the echo pin, and returns the sound wave travel time in microseconds
	return pulseIn(echoPin, HIGH);
}

void setup()
{
	Serial.begin(9600);
  	lcd.begin(16,2);
  	lcd.setCursor(3,0);
  	lcd.print("Smart Mask");
  	delay(3000);
  	lcd.clear();
  pinMode(11, OUTPUT);
}

void loop()
{
	sensorvalue = 0.01723 * readUltrasonicDistance(13, 12);
	Serial.println(sensorvalue);
  	lcd.setCursor(0,0);
  	lcd.print(sensorvalue);
  	lcd.print(" cm");
	delay(500); // Wait for 500 millisecond(s)
	if (sensorvalue >= 200){
		digitalWrite(11, LOW);
      	lcd.clear();
      	lcd.setCursor(0,1);
      	lcd.print("You're Safe");
      digitalWrite(13, LOW);
	}
	if (sensorvalue < 200) {
		digitalWrite(11, HIGH);
      	lcd.clear();
      	lcd.setCursor(0,1);
      	lcd.print("Move back!!");
      digitalWrite(13, HIGH);
	}
}