[嵌入式]51单片机入门——矩阵建盘的基本操作（待更新）

矩阵键盘的原理图和基本原理

• 原理图

• 基本原理

首先我们要进行扫描，扫描矩阵键盘中每个按键的状态，对与矩阵键盘，我们只能逐行扫描，然后读取列的状态信号。如果R3行输出低电平，那么黄色按键如果有按下动作的话，那读取C2列信号也应该为低电平，而该行上其他没有按下动作的按键的列信号则为高电平。
每个按键内部的结构

• 独立按键
  

- 矩阵键盘

检测

每次输入检测是都只保证一个为低电平，其余为高电平，只要某一行输入0,在某一列也输出0，则检测成功（成功按下）

例题

代码如下

#include "reg52.h"  

sfr P4   = 0xC0;    

sbit HC138_A = P2^5;    
sbit HC138_B = P2^6;    
sbit HC138_C = P2^7;    

sbit R1 = P3^0;  
sbit R2 = P3^1;
sbit R3 = P3^2;
sbit R4 = P3^3;

sbit C1 = P4^4;
sbit C2 = P4^2;
sbit C3 = P3^5;
sbit C4 = P3^4;

unsigned char keyNum = 0x10;
unsigned char code SMG_NoDot[18] = 
    {0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,
     0x80,0x90,0x88,0x80,0xc6,0xc0,0x86,0x8e,
     0xbf,0x7f};

void Delay(unsigned char t)
{
    while(t--);
}

void Init74HC138(unsigned char n)
{
    switch(n)
    {
        case 4:
            HC138_A = 0;
            HC138_B = 0;
            HC138_C = 1;
            break;
        case 5:
            HC138_A = 1;
            HC138_B = 0;
            HC138_C = 1;
            break;
        case 6:
            HC138_A = 0;
            HC138_B = 1;
            HC138_C = 1;
            break;
        case 7:
            HC138_A = 1;
            HC138_B = 1;
            HC138_C = 1;
            break;
        case 8:
            HC138_A = 0;
            HC138_B = 0;
            HC138_C = 0;
            break;
    }
}

void ShowKeyNum(unsigned char value)
{
    Init74HC138(6);
    P0 = 0x01;
    Init74HC138(7);
    P0 = value;
}

void ScanKeys()
{
    keyNum = 16;
    R1 = 0;
    R2 = R3 = R4 = 1;
    C1 = C2 = C3 = C4 = 1;
    if(C1 == 0)
    {
        while(C1 == 0);
        keyNum = 0;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C2 == 0)
    {
        while(C2 == 0);
        keyNum = 1;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C3 == 0)
    {
        while(C3 == 0);
        keyNum = 2;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C4 == 0)
    {
        while(C4 == 0);
        keyNum = 3;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    
    R2 = 0;
    R1 = R3 = R4 = 1;
    C1 = C2 = C3 = C4 = 1;
    if(C1 == 0)
    {
        while(C1 == 0);
        keyNum = 4;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C2 == 0)
    {
        while(C2 == 0);
        keyNum = 5;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C3 == 0)
    {
        while(C3 == 0);
        keyNum = 6;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C4 == 0)
    {
        while(C4 == 0);
        keyNum = 7;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    
    R3 = 0;
    R2 = R1 = R4 = 1;
    C1 = C2 = C3 = C4 = 1;
    if(C1 == 0)
    {
        while(C1 == 0);
        keyNum = 8;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C2 == 0)
    {
        while(C2 == 0);
        keyNum = 9;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C3 == 0)
    {
        while(C3 == 0);
        keyNum = 10;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C4 == 0)
    {
        while(C4 == 0);
        keyNum = 11;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    
    R4 = 0;
    R2 = R3 = R1 = 1;
    C1 = C2 = C3 = C4 = 1;
    if(C1 == 0)
    {
        while(C1 == 0);
        keyNum = 12;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C2 == 0)
    {
        while(C2 == 0);
        keyNum = 13;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C3 == 0)
    {
        while(C3 == 0);
        keyNum = 14;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
    else if(C4 == 0)
    {
        while(C4 == 0);
        keyNum = 15;
        ShowKeyNum(SMG_NoDot[keyNum]);
    }
}

void main()
{    
    while(1)
    {
        ScanKeys();
    }
}