任務簡述：通過按下4X4矩陣鍵盤實現數碼管對應顯示數字

實現方式：通過行列分接法，可以節省使用單片機的I/O口，掃描矩陣鍵盤是否有按下，判斷P2端口得到的值。

protues 硬件系統

單片機晶振復位電路：

鎖存器、上拉電阻：

4x4矩陣鍵盤：

代碼實現：

void key44scan(void)//鍵盤掃描函數
{
    uint t;
    P2=0xfe;
    t=P2;
    t=t&0xf0;
    if(t!=0xf0)
    {
        delay();
        t=P2;
    
        switch(t)
        {
              
 
case 0xee:keynum=1; break;
              case 0xde:keynum=5; break;
              case 0xbe:keynum=9; break;
              case 0x7e:keynum=13; break;             
        }
        P0=table[keynum];
        while(t!=0xf0)
        {
             t=P2;
             t=t&0xf0;
        }
    }




    P2=0xfd
 
;
    t=P2;
    t=t&0xf0;
    if(t!=0xf0)
    {
        delay();
        t=P2;
        
        switch(t)
        {
              case 0xed:keynum=2; break;
              case 0xdd:keynum=6; break;
              case 0xbd:keynum=10; break;
              case 0x7d:keynum=14; break;             
        }
        P0
 
=table[keynum];
        while(t!=0xf0)
        {
             
             t=P2;
             t=t&0xf0;
        }
    }


    P2=0xfb;
    t=P2;
    t=t&0xf0;
    if(t!=0xf0)
    {
        delay();
        t=P2;
    
        switch(t)
        {
              case 0xeb:keynum=3; break;
              case 0xdb:keynum=7; break;
              case 0xbb:keynum=11; break;
              case 0x7b:keynum=15; break;             
        }
        P0=table[keynum];
            while(t!=0xf0)
        {
             
             t=P2;
             t=t&0xf0;
        }
    }




    P2=0xf7;
    t=P2;
    t=t&0xf0;
    if(t!=0xf0)
    {
        delay();
        t=P2;
    
        switch(t)
        {
              case 0xe7:keynum=4; break;
              case 0xd7:keynum=8; break;
              case 0xb7:keynum=12; break;
              case 0x77:keynum=0; break;             
        }
        P0=table[keynum];
        while(t!=0xf0)
        {
             
             t=P2;
             t=t&0xf0;
        }
    }
}

單片機入門-矩陣鍵盤控制數碼管顯示