51单片机第三讲（矩阵键盘）

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/hu_junhua/article/details/79221450

1.原理图

直接上代码：

#define MKEYPORT P0

unsigned char Mkeyscan(void)
{
    unsigned char temp = 0;
    MKEYPORT = 0xf0;        //四行全部开启扫描

    if(MKEYPORT != 0xf0)   //说明有按键按下
    {
        MKEYPORT = 0xfe;      //第一行扫描
        if(MKEYPORT != 0xfe)
        {
            delay_ms(10);    //消抖
            if(MKEYPORT != 0xfe)
            {
                temp = MKEYPORT;
            }
        }

        MKEYPORT = 0xfd;      //第二行扫描
        if(MKEYPORT != 0xfd)
        {
            delay_ms(10);    //消抖
            if(MKEYPORT != 0xfd)
            {
                temp = MKEYPORT;
            }
        }

        MKEYPORT = 0xfb;      //第三行扫描
        if(MKEYPORT != 0xfb)
        {
            delay_ms(10);//消抖
            if(MKEYPORT != 0xfb)
            {
                temp = MKEYPORT;
            }
        }

        MKEYPORT = 0xf7;      //第四行扫描
        if(MKEYPORT != 0xf7)
        {
            delay_ms(10);//消抖
            if(MKEYPORT != 0xf7)
            {
                temp = MKEYPORT;
            }
        }
    }

    else//没有按键按下
    {
        temp = 0xff;
    }

    return temp;
}

unsigned char Mkey_Proc(void)
{
    unsigned char Mkeyvalue = 0x99;

    switch(Mkeyscan())
    {
        case 0x7e:
        Mkeyvalue = 1;
        break;

        case 0xbe:
        Mkeyvalue = 2;
        break;

        case 0xde:
        Mkeyvalue = 3;
        break;

        case 0xee:
        Mkeyvalue = 4;
        break;

        case 0x7d:
        Mkeyvalue = 5;
        break;

        case 0xbd:
        Mkeyvalue = 6;
        break;

        case 0xdd:
        Mkeyvalue = 7;
        break;

        case 0xed:
        Mkeyvalue = 8;
        break;

        case 0x7b:
        Mkeyvalue = 9;
        break;

        case 0xbb:
        Mkeyvalue = 10;
        break;

        case 0xdb:
        Mkeyvalue = 11;
        break;

        case 0xeb:
        Mkeyvalue = 12;
        break;

        case 0x77:
        Mkeyvalue = 13;
        break;

        case 0xb7:
        Mkeyvalue = 14;
        break;

        case 0xd7:
        Mkeyvalue = 15;
        break;

        case 0xe7:
        Mkeyvalue = 16;
        break;

        default :
        Mkeyvalue = 0x99;
    }   

    return Mkeyvalue;
}