先判断列在判断行

举个例子 假设 按下 S7 （第一行的第二列）
P3 = 0xf0; 1111 0000 P3 = 1101 0000
P3 & 0xf0 舍弃行 保留列 1101 0000 行值
P3 = cord_l | 0x0f 将 1101 1111 => 1101 1110
P3 & 0x0f 0000 1110 列值
行+列
1101 1110

#include<reg52.h>
#define uint unsigned int
#define uchar unsigned char
sbit we = P2^7;
sbit du = P2^6;
void delay(uint z)
{
    uint x,y;
    for(x = z; x>0; x--)
        for(y = 114;y>0;y--);
}

uchar code leddata[]={ 
 
                0x3F,  //"0"
                0x06,  //"1"
                0x5B,  //"2"
                0x4F,  //"3"
                0x66,  //"4"
                0x6D,  //"5"
                0x7D,  //"6"
                0x07,  //"7"
                0x7F,  //"8"
                0x6F,  //"9"
                0x77,  //"A"
                0x7C,  //"B"
                0x39,  //"C"
                0x5E,  //"D"
                0x79,  //"E"
                0x71,  //"F"
                0x76,  //"H"
                0x38,  //"L"
                0x37,  //"n"
                0x3E,  //"u"
                0x73,  //"P"
                0x5C,  //"o"
                0x40,  //"-"
                0x00,  //熄灭
                0x00  //自定义
 
                         };
uchar KeyScan()
{
    uchar cord_l,cord_h;
    P3 = 0xf0;   // 1111 0000
    if((P3&0xf0)!=0xf0)
    {   //判断是否有按键按下
        //自判断高位 
        delay(5); //软件消抖
        if((P3&0xf0)!=0xf0)
        {
            cord_l = P3&0xf0;//这样写不考虑行线
            P3 = cord_l|0x0f;
            cord_h = P3&0x0f; //储存行线值
            while((P3&0x0f)!=0x0f); //判断按完？
            return (cord_l+cord_h);//返回值
        }
    }
}

void KeyPro()
{
    switch( KeyScan() )
    {
        //第一行键值码
        case 0xee: P0 = leddata[0];     break;
        case 0xde: P0 = leddata[1];     break;
        case 0xbe: P0 = leddata[2];     break;
        case 0x7e: P0 = leddata[3];     break;
        
        //第二行键值码
        case 0xed: P0 = leddata[4];     break;
        case 0xdd: P0 = leddata[5];     break;
        case 0xbd: P0 = leddata[6];     break;
        case 0x7d: P0 = leddata[7];     break;

        //第三行键值码
        case 0xeb: P0 = leddata[8];     break;
        case 0xdb: P0 = leddata[9];     break;
        case 0xbb: P0 = leddata[10];    break;
        case 0x7b: P0 = leddata[11];    break;

        //第四行键值码
        case 0xe7: P0 = leddata[12];    break;
        case 0xd7: P0 = leddata[13];    break;
        case 0xb7: P0 = leddata[14];    break;
        case 0x77: P0 = leddata[15];    break;
    }   
}

int main()
{
    we = 1;
    P0 = 0x00;
    we = 0;

    du = 1;
    P0 = leddata[22];
    while(1)
    {     
        
        KeyPro();

    }
    return 0;
}

switch 按下的按键对应一个数值