//定义数码管引脚数组seg
int seg[2][7] =
{ { 2, 3, 4, 5, 6, 7, 8},
{ 9, 10, 11, 12, 13, 14, 15 } };

const int button_pause = 16;
const int button_decrease = 17;
const int button_increase = 18;
const int button_reverse = 19;
const int ledPinRed = 20;
const int ledPinYellow = 21;
const int ledPinGreen = 22;
const int ledPinBlue = 23;
const int ledPinWhite = 24;
int increasePressed = LOW;
int decreasePressed = LOW;
int pausePressed = LOW;
int reversePressed = LOW;
int seconds = 100;
int paused = false;
int reverse = false;
void setup()
{
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(13, OUTPUT);
  pinMode(14, OUTPUT);
  pinMode(15, OUTPUT);
  //初始化按钮引脚为输入模式，并启用内部上拉电阻
  pinMode(button_increase, INPUT);
  pinMode(button_decrease, INPUT);
  pinMode(button_pause, INPUT);
  pinMode(button_reverse, INPUT);
  pinMode(ledPinRed, OUTPUT);
  pinMode(ledPinYellow, OUTPUT);
  pinMode(ledPinGreen, OUTPUT);
  pinMode(ledPinBlue, OUTPUT);
  pinMode(ledPinWhite, OUTPUT);
  // 初始化串口通信
  Serial.begin(9600);
}

void loop()//循环函数
{
  //读取按钮状态
  increasePressed = digitalRead(button_increase);
  decreasePressed = digitalRead(button_decrease);
  pausePressed = digitalRead(button_pause);
  reversePressed = digitalRead(button_reverse);

  //暂停，继续计时
  if ( pausePressed == HIGH )
  {
    paused = !paused;
    if ( paused )
    {
      digitalWrite(ledPinRed, HIGH);//暂停的时候红灯常亮
    } else {
      digitalWrite(ledPinRed, LOW);//暂停的时候红灯熄灭
    }
    delay(500);
  }
  //增加秒数
  if (increasePressed == HIGH  )
  {
    seconds+=10;//+10s
    digitalWrite(ledPinGreen, HIGH);
    delay(500);
    digitalWrite(ledPinGreen, LOW);
  }
  //减少秒数
  if (decreasePressed == HIGH  && seconds > 0)
  {
    seconds-=10;//，-10s
    digitalWrite(ledPinYellow, HIGH);
    delay(500);
    digitalWrite(ledPinYellow, LOW);
  }

  //展示当今模式所亮的灯，蓝灯代表倒计时，白灯代表正计时
  if ( !reverse )
  {//代表倒计时的蓝灯常亮
    digitalWrite(ledPinWhite, LOW);
    digitalWrite(ledPinBlue, HIGH);
  } else {//代表正计时的白灯常亮
    digitalWrite(ledPinBlue, LOW);
    digitalWrite(ledPinWhite, HIGH);
  }
  //倒计时和正计时互换模式
  if ( reversePressed == HIGH )
  {
      reverse = !reverse;
    delay(500);
  }

  if ( !paused )
  {
    if ( !reverse )//默认的reverse是false，这个时候是默认倒计时
    {
      seconds--;
    } else {//正计时
      seconds++;
    }
  //输出秒数
  displaySeconds();
  Serial.println(seconds);
  }
}

void displaySeconds()
{
  int units = seconds % 10;//个位数
  int tens = (seconds / 10) % 10;//十位数
  int flash = 5 - (tens/3);//闪烁频率
  //数码管显示数字
  displayDigit(1,tens);
  displayDigit(0,units);
  for (int i=0 ; i<flash ; i++ )
  {
    //十位数的9对应2次闪烁，6-8对应3次，3-5对应4次，0-2对应5次，即倒计数越小LED灯闪烁频率就越高
    flash = 5 - (tens/3);
    digitalWrite(ledPinRed, HIGH);
    delay(500/flash);
    digitalWrite(ledPinRed, LOW);
    delay(500/flash);
  }
}

void displayDigit( int index, int digit )
{
  //根据数码管显示数字
  switch (digit)
  {
    case 0:
      digitalWrite(seg[index][0], HIGH);
      digitalWrite(seg[index][1], HIGH);
      digitalWrite(seg[index][2], HIGH);
      digitalWrite(seg[index][3], HIGH);
      digitalWrite(seg[index][4], HIGH);
      digitalWrite(seg[index][5], HIGH);
      digitalWrite(seg[index][6], LOW);
      break;
    case 1:
      digitalWrite(seg[index][0], LOW);
      digitalWrite(seg[index][1], HIGH);
      digitalWrite(seg[index][2], HIGH);
      digitalWrite(seg[index][3], LOW);
      digitalWrite(seg[index][4], LOW);
      digitalWrite(seg[index][5], LOW);
      digitalWrite(seg[index][6], LOW);
      break;
    case 2:
      digitalWrite(seg[index][0], HIGH);
      digitalWrite(seg[index][1], HIGH);
      digitalWrite(seg[index][2], LOW);
      digitalWrite(seg[index][3], HIGH);
      digitalWrite(seg[index][4], HIGH);
      digitalWrite(seg[index][5], LOW);
      digitalWrite(seg[index][6], HIGH);
      break;
    case 3:
      digitalWrite(seg[index][0], HIGH);
      digitalWrite(seg[index][1], HIGH);
      digitalWrite(seg[index][2], HIGH);
      digitalWrite(seg[index][3], HIGH);
      digitalWrite(seg[index][4], LOW);
      digitalWrite(seg[index][5], LOW);
      digitalWrite(seg[index][6], HIGH);
      break;
    case 4:
      digitalWrite(seg[index][0], LOW);
      digitalWrite(seg[index][1], HIGH);
      digitalWrite(seg[index][2], HIGH);
      digitalWrite(seg[index][3], LOW);
      digitalWrite(seg[index][4], LOW);
      digitalWrite(seg[index][5], HIGH);
      digitalWrite(seg[index][6], HIGH);
      break;
    case 5:
      digitalWrite(seg[index][0], HIGH);
      digitalWrite(seg[index][1], LOW);
      digitalWrite(seg[index][2], HIGH);
      digitalWrite(seg[index][3], HIGH);
      digitalWrite(seg[index][4], LOW);
      digitalWrite(seg[index][5], HIGH);
      digitalWrite(seg[index][6], HIGH);
      break;
    case 6:
      digitalWrite(seg[index][0], HIGH);
      digitalWrite(seg[index][1], LOW);
      digitalWrite(seg[index][2], HIGH);
      digitalWrite(seg[index][3], HIGH);
      digitalWrite(seg[index][4], HIGH);
      digitalWrite(seg[index][5], HIGH);
      digitalWrite(seg[index][6], HIGH);
      break;
    case 7:
      digitalWrite(seg[index][0], HIGH);
      digitalWrite(seg[index][1], HIGH);
      digitalWrite(seg[index][2], HIGH);
      digitalWrite(seg[index][3], LOW);
      digitalWrite(seg[index][4], LOW);
      digitalWrite(seg[index][5], LOW);
      digitalWrite(seg[index][6], LOW);
      break;
    case 8:
      digitalWrite(seg[index][0], HIGH);
      digitalWrite(seg[index][1], HIGH);
      digitalWrite(seg[index][2], HIGH);
      digitalWrite(seg[index][3], HIGH);
      digitalWrite(seg[index][4], HIGH);
      digitalWrite(seg[index][5], HIGH);
      digitalWrite(seg[index][6], HIGH);
      break;
    case 9:
      digitalWrite(seg[index][0], HIGH);
      digitalWrite(seg[index][1], HIGH);
      digitalWrite(seg[index][2], HIGH);
      digitalWrite(seg[index][3], HIGH);
      digitalWrite(seg[index][4], LOW);
      digitalWrite(seg[index][5], HIGH);
      digitalWrite(seg[index][6], HIGH);
      break;
  }
}