Mega16按键与数码显示程序

#include  
#define No_key 255 
#define K1_11 
#define K1_22 
#define K1_33 
#define K1_4    4 
#define K2_15 
#define K2_26 
#define K2_37 
#define K2_4    8 
#define K3_19 
#define K3_20 
#define K3_310 
#define K3_4    11 
#define K4_112 
#define K4_213 
#define K4_314 
#define K4_4    15 
#define Key_mask0b00001111   
#define data PORTB.0 
#define clk PORTB.1  
flash unsigned char led[16]={0x28,0xeb,0x19,0x89,0xca,0x8c,0x0c,0xe9,0x08,0x88, 
                             0xdf,0x4a,0x1c,0x3e,0x7e,0x2a}; 
unsigned charkey_stime_counter; 
unsigned char   key_temp; 
bitkey_stime_ok;  
//D0接键盘，低4位列线输入，高4位行线输出 
unsigned char read_keyboard() 
{ 
 static unsigned char key_state = 0, key_value, key_line; 
 unsigned char key_return = No_key,i; 
 switch (key_state) 
 { 
  case 0: 
  key_line = 0b00010000; 
  for (i=1; i<=4; i++)// 扫描键盘 
  { 
         PORTA = ~key_line;// 输出行线电平 
 PORTA = ~key_line;// 必须送2次！！！ 
 key_value = Key_mask & PINA;// 读列电平 
 if (key_value == Key_mask) 
 key_line <<= 1;// 没有按键，继续扫描 
 else 
 { 
  key_state++;// 有按键，停止扫描 
  break;// 转消抖确认状态 
 } 
} 
break; 
  case 1: 
        if (key_value == (Key_mask & PINA))// 再次读列电平， 
{ 
 switch (key_line | key_value)// 与状态0的相同，确认按键 
 {// 键盘编码，返回编码值  
  case 0b00011110: 
       key_return = K1_1; 
       break; 
  case 0b00011101: 
       key_return = K1_2; 
       break; 
          case 0b00011011: 
       key_return = K1_3; 
       break; 
  case 0b00010111: 
       key_return = K1_4; 
       break;      
  case 0b00101110: 
       key_return = K2_1; 
       break; 
   case 0b00101101: 
       key_return = K2_2; 
       break; 
  case 0b00101011: 
       key_return = K2_3; 
       break; 
  case 0b00100111: 
       key_return = K2_4; 
       break; 
   case 0b01001110: 
       key_return = K3_1; 
       break; 
   case 0b01001101: 
       key_return = K3_2; 
       break; 
  case 0b01001011: 
       key_return = K3_3; 
       break;  
  case 0b01000111: 
       key_return = K3_4; 
       break; 
   case 0b10001110: 
       key_return = K4_1; 
       break; 
   case 0b10001101: 
       key_return = K4_2; 
       break; 
  case 0b10001011: 
       key_return = K4_3; 
       break;  
  case 0b10000111: 
       key_return = K4_4; 
       break; 
 } 
key_state++;// 转入等待按键释放状态 
       } 
       else 
 { 
  key_state--; 
  delay_ms(5); 
 }// 两次列电平不同返回状态0，（消抖处理） 
 break; 
  case 2:// 等待按键释放状态 
      PORTA = 0b00001111;// 行线全部输出低电平 
      PORTA = 0b00001111;// 重复送一次 
      if ( (Key_mask & PINA) == Key_mask) 
      key_state=0;// 列线全部为高电平返回状态0 
      break; 
 } 
 return key_return; 
} 
//向数码管送入数据 
void sendbyte(unsigned char byte) 
{     
 unsigned char num,c;  
 num=led[byte]; 
 for(c=0;c<8;c++) 
 { 
  clk=0; 
  data=num&0x01; 
  clk=1; 
  num>>=1; 
 } 
} 
void display(void) 
{ 
 if (key_stime_ok) 
  { 
   key_stime_ok = 0;// 10ms到 
   key_temp = read_keyboard();// 调用键盘接口函数读键盘 
   if (key_temp != No_key) 
   {// 有按键按下 
    sendbyte(key_temp); 
    delay_ms(10); 
   } 
  } 
} 
void main(void) 
{ 
 DDRB = 0xFF; 
 //PORTC = 0xFF;// 键盘接口初始化 
 DDRA = 0xF0;// PD2、PD1、PD0列线，输入方式，上拉有效 
 // T/C0 初始化  
 TCCR0=0x0B;// 内部时钟，64分频（4M/64=62.5KHz），CTC模式 
 TCNT0=0x00; 
 OCR0=0x7C;// OCR0 = 0x7C(124),(124+1)/62.5=2ms 
 TIMSK=0x02;// 允许T/C0比较匹配中断 
 #asm("sei")// 开放全局中断 
 while (1) 
 { 
  display(); 
 } 
}      
// Timer 0 比较匹配中断服务,2ms定时 
interrupt [TIM0_COMP] void timer0_comp_isr(void) 
{ 
 //display();// 调用LED扫描显示 
 if (++key_stime_counter >=5) 
 { 
  key_stime_counter = 0; 
  key_stime_ok = 1;// 10ms到 
 } 
}