#include"LiquidCrystal.h"
#include"stdlib.h"
#include"SR04.h"
LiquidCrystal lcd(11,10,5,6,7,8);

#define TRIG_PIN 2
#define ECHO_PIN 3
char str1[]="dis:";
SR04 sr04 =SR04(3,2);
long a;
int buzzer=11;
void setup(void) {
 lcd.begin(16,2);
 Serial.begin(115200);
 pinMode(buzzer,OUTPUT);
 delay(1000);

}

void loop(void) {
  lcd.setCursor(0,0);
  lcd.print(str1);
  a=sr04.Distance();
  Serial.println(a);
  lcd.print(a);
  lcd.print("cm ");
  if(a<50){
    digitalWrite(buzzer,HIGH);
    delay((a/10)*100+(a%10)*5);
    digitalWrite(buzzer,LOW);
    delay((a/10)*100+(a%10)*5);
  }
  else
  digitalWrite(buzzer,LOW);
}