要求：按下键盘，六个数码管流动显示按下的值。

连线:将片选CS0接到key_LED_CS上


#include  <reg52.h>

#define   LEDLen   6


xdata unsigned char OUTBIT _at_ 0x8002;   // 位控制口
xdata unsigned char OUTSEG _at_ 0x8004;   // 段控制口
xdata unsigned char IN     _at_ 0x8001;   // 键盘读入口


unsigned char LEDBuf[LEDLen];    // 显示缓冲
code unsigned char LEDMAP[] = {  // 八段管显示码 (点不显示，0-F）
  0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07,
  0x7f, 0x6f, 0x77, 0x7c, 0x39, 0x5e, 0x79, 0x71
};


code unsigned char KeyTable[] = {   // 键码定义
  0x16, 0x15, 0x14, 0xff,
  0x13, 0x12, 0x11, 0x10,
  0x0d, 0x0c, 0x0b, 0x0a,
  0x0e, 0x03, 0x06, 0x09,
  0x0f, 0x02, 0x05, 0x08,
  0x00, 0x01, 0x04, 0x07
};




void Delay(unsigned char CNT)
{
  unsigned char i;
  while (CNT-- !=0)
    for (i=100; i !=0; i--);
}


void DisplayLED()
{
  unsigned char i;
  unsigned char Pos;
  unsigned char LED;


  Pos = 0x20;       // 从左边开始显示
  for (i = 0; i < LEDLen; i++) {
    OUTBIT = 0;     // 关所有八段管
    LED = LEDBuf[i];
    OUTSEG = LED;
    OUTBIT = Pos;   // 显示一位八段管
    Delay(2);
    Pos >>= 1;      // 显示下一位
  }
}




unsigned char TestKey()
{
   OUTBIT = 0;            // 输出线置为0
   return (~IN & 0x0f);   // 读入键状态(高四位不用)
}


unsigned char GetKey()
{
  unsigned char Pos;
  unsigned char i;
  unsigned char k;


  i = 6;
  Pos = 0x20;     // 找出键所在列
  do {
    OUTBIT = ~ Pos;
    Pos >>= 1;
    k = ~IN & 0x0f;
  } while ((--i != 0) && (k == 0));


  // 键值 = 列 x 4 + 行
  if (k != 0)
  {
    i *= 4;
    if (k & 2)
      i += 1;
    else if (k & 4)
      i += 2;
    else if (k & 8)
      i += 3;


    OUTBIT = 0;
    do
      Delay(10); while (TestKey());  // 等键释放


    return(KeyTable[i]);  // 取出键码
  } else return(0xff);
}


void main()
{    unsigned int i=0;
   LEDBuf[0] = 0x00;  //如果设置为3F那么最初第一个数码管显示为0
   LEDBuf[1] = 0x00;
   LEDBuf[2] = 0x00;
   LEDBuf[3] = 0x00;
   LEDBuf[4] = 0x00;
   LEDBuf[5] = 0x00;


   while (1) {
     DisplayLED();
     if (TestKey())
     {


         LEDBuf[i++%6] = LEDMAP[GetKey() & 0x0f];
       //LEDBuf[5]=LEDMP[GetKey()&0x0f];
     }
   }
}