int ledPin = 13;               
int inputPin = 2;               
int pirState = LOW;          //假设无运动
int val = 0;                   
#define SPEAKER_PIN 12
#include <LiquidCrystal_I2C.h>   //加载库文件
LiquidCrystal_I2C lcd(0x27,20,4); 
void setup() {
  pinMode(ledPin, OUTPUT);      // led为输出状态
  pinMode(inputPin, INPUT);     // 传感器为输入状态
  lcd.init();                      // 初始化LCD
  lcd.backlight();                //LCD背景亮
  Serial.begin(9600);
  pinMode(SPEAKER_PIN, OUTPUT);   //蜂鸣器引脚状态
}


void loop() {
  val = digitalRead(inputPin);  // 读取输入值
  if (val == HIGH) {            // 检测是否输入HIGH
    digitalWrite(ledPin, HIGH);  // LED打开
    if (pirState == LOW) {         
      lcd.print("1");          //LCD 显示1
       tone(SPEAKER_PIN, 500); //蜂鸣器响
      pirState = HIGH;         
      lcd.home();              //lcd从头开始
    }
    
  } else {
    digitalWrite(ledPin, LOW); // 关闭LED
    if (pirState == HIGH) {    
      lcd.print("0");          //LCD显示0 
      pirState = LOW;
      noTone(SPEAKER_PIN);     //关闭蜂鸣器
      lcd.home();              //lcd 从头开始
    }
  }
}