const int dataPin = 35;
const int clockPin = 37;
const int latchPin = 36;
const int keyPin = 18;    //将改成端口4,编程用4,不然程序下载有问题

int preKeyVal = 0;
int keyState = 1;
int preKeyState = 1;
boolean keyFlag= false;
boolean countFlag = false;
unsigned int preTime = 0;
int debounceDelay = 10;
unsigned int number = 0;
unsigned int currentTime = 0;   //一定声明为全局变量，不然该变量每进一次loop都会清零
 
const byte num[]={
    0xC0,    //0  共阳   0b11000000
    0xF9,    //1
    0xA4,
    0xB0,
    0x99,
    0x92,
    0x82,
    0xF8,
    0x80,
    0x90,
    0x7F    //小数点
  };

void setup() {
  // put your setup code here, to run once:
  //设置dataPin为输出模式
  //设置clockPin为输出模式
  //设置latchPin为输出模式
  //设置keyPin为输入模式
    pinMode(dataPin,OUTPUT);
    pinMode(clockPin,OUTPUT);
    pinMode(latchPin,OUTPUT);
    pinMode(keyPin,INPUT);
  //clocPin输出低电平
  //latchPin输出低电平
    digitalWrite(clockPin,LOW);
    digitalWrite(latchPin,LOW);
    Serial.begin(115200);
}

void getKeyState()
//获取按键状态
{
    int keyVal = digitalRead(keyPin); 
    if(keyVal != preKeyVal)   
    //看看什么时候按键状态有变化，把这时候的时间点取出来
    //如果按键值不等于0，即如果按键值为1
    //取主板开始运行到现在的时间值（ms）
    //变量preKeyVal等于keyVal的值，即获取当前时间点的按键状态写入preKeyVal
    {
        preTime = millis();
        preKeyVal = keyVal;  
    }

    if((millis()-preTime) > debounceDelay) 
     //10ms 扫描一次
     //如果当前时间与按键变化时间点大于10
     //如果按键值不等于1，即如果按键值等于0
     //按键状态值存储变量keyVal等于按键值keyVal
    {
        if(keyVal != preKeyState) 
        {
            preKeyState = keyVal;
            if(HIGH == keyVal)
     //如果按键值等于高电位
            {
                keyFlag = !keyFlag; 
    //按键状态变量keyFlag取反 
            }  
        }
    }
}

void displayNum(int number)
{
    if(number > 1234)
    {
      number = 1234;  
    }
    int ge = 0;
    int shi = 0;
    int bai = 0;
    int qian = 0;

    qian = int(number/1000);
    shiftOut(dataPin,clockPin,MSBFIRST,0b00000001);
    shiftOut(dataPin,clockPin,MSBFIRST,num[qian]);
    digitalWrite(latchPin,HIGH);
    delay(50);
    digitalWrite(latchPin,LOW);

    number = number%1000;    
    bai = int(number/100);  
    shiftOut(dataPin,clockPin,MSBFIRST,0b00000010);
    shiftOut(dataPin,clockPin,MSBFIRST,num[bai]);
    digitalWrite(latchPin,HIGH);
    delay(50);
    digitalWrite(latchPin,LOW);

    number = number % 100;    
    shi = int(number/10);
    shiftOut(dataPin,clockPin,MSBFIRST,0b00000100);
    shiftOut(dataPin,clockPin,MSBFIRST,num[shi]);
    digitalWrite(latchPin,HIGH);
    delay(50);
    digitalWrite(latchPin,LOW);

    ge = number % 10;    
    shiftOut(dataPin,clockPin,MSBFIRST,0b00001000);
    shiftOut(dataPin,clockPin,MSBFIRST,num[ge]);
    digitalWrite(latchPin,HIGH);
    delay(50);
    digitalWrite(latchPin,LOW);
}
void loop() {
    getKeyState();
    if(true)     //keyFlag = true    
    {
        if(countFlag == true)
        {
            currentTime = millis(); 
            countFlag = false;
        }
       number = millis() - currentTime;   
    }
    else
    {
        countFlag = true;
    }
    displayNum(number);
}