蓝桥杯51单片机-矩阵键盘扫描原理和基本应用_51单片机c4

基本功能：编写矩阵按键程序，实现每按下一个按键依次显示0-F。

以上为我们实现基本功能所需要使用的元器件

注意：我们需要使用矩阵键盘，需要将J5的跳帽盖在1,2的位置。由于使用的是IAP单片机，则P36,P37端口分别改为P42,P44

接下来我们来分析矩阵键盘的扫描原理，我们以具体的代码来分析

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;
 
void Delay1ms(unsigned char x)
{
    while(x--)
    {
        unsigned char i,j;
        i=12;
        j=169;
        do
        {
            while(--j);
        } while(--i);
    }
}
void ScanKeysMulti()//ROW行/column列
{
    R1=0;
    R2=R3=R4=1;
    C1=C2=C3=C4=1;
    if(C1==0)
    {
        Delay1ms(5);
        if(C1==0)
        {
            while(C1==0);
            key=0;
            
        }
    }
    else if(C2==0)
    {
        Delay1ms(5);
        if(C2==0)
        {
            while(C2==0);
            key=1;
            
        }
    }
    else if(C3==0)
    {
        Delay1ms(5);
        if(C3==0)
        {
            while(C3==0);
            key=2;
            
        }
    }
    else if(C4==0)
    {
        Delay1ms(5);
        if(C4==0)
        {
            while(C4==0);
            key=3;
            
        }
    }
		
}

矩阵键盘的扫描原理我们可以把键盘分为两部分理解，分别为行和列，我们来看这行代码

    R1=0;
    R2=R3=R4=1;
    C1=C2=C3=C4=1;

每一列我们都设为高电平，而在行里，只有第一行是低电平，其他行是高电平，根据原理图，当我们随机按下第一行的一个按键S7,S11,S15,S19时，那它对应的列也会被拉低，变成低电平，而其他列一直保持高电平，此时我们就能通过哪一列为低电平来判断是哪个按键被按下。也就是说，当执行以上代码时，按键的行先被确定，默认为第一行，再通过哪一列为低电平判断按键的列，当这两个部分都被确定好之后，那么是哪个按键被按下我们就能得知了，明白这些之后，我们就能很轻松地完成基本功能，以下是代码。

#include "reg52.h"
 
sfr P4    = 0xC0;
 
sbit R1 = P3^0;
sbit R2 = P3^1;
sbit R3 = P3^2;
sbit R4 = P3^3;
 
sbit C4 = P3^4;
sbit C3 = P3^5;
sbit C2 = P4^2;
sbit C1 = P4^4;
 
unsigned char code SMG_duanma[18]=
		{0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,
     0x80,0x90,0x88,0x80,0xc6,0xc0,0x86,0x8e,
     0xbf,0x7f};
		 
void SelectHC573(unsigned char channel)
{
	switch(channel)
	{
		case 4:
			P2 = (P2 & 0x1f) | 0x80;
		break;
		case 5:
			P2 = (P2 & 0x1f) | 0xa0;
		break;
		case 6:
			P2 = (P2 & 0x1f) | 0xc0;
		break;
		case 7:
			P2 = (P2 & 0x1f) | 0xe0;
		break;
	}
}
 
void DisplayKeyNum(unsigned char value)
{
	P0 = 0xff;
	SelectHC573(6);
	P0 = 0x01;
	SelectHC573(7);
	P0 = value;
}
 
unsigned char key_num;
void ScanKeysMulti()//ROW行/column列
{
	R1 = 0;
	R2 = R3 = R4 = 1;
	C1 = C2 = C3 = C4 =1;
	if(C1 == 0)
	{
		while(C1 == 0);
		key_num = 0;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C2 == 0)
	{
		while(C2 == 0);
		key_num = 1;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C3 == 0)
	{
		while(C3 == 0);
		key_num = 2;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C4 == 0)
	{
		while(C4 == 0);
		key_num = 3;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	
	R2 = 0;
	R1 = R3 = R4 = 1;
	C1 = C2 = C3 = C4 =1;
	if(C1 == 0)
	{
		while(C1 == 0);
		key_num = 4;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C2 == 0)
	{
		while(C2 == 0);
		key_num = 5;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C3 == 0)
	{
		while(C3 == 0);
		key_num = 6;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C4 == 0)
	{
		while(C4 == 0);
		key_num = 7;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	
	R3 = 0;
	R2 = R1 = R4 = 1;
	C1 = C2 = C3 = C4 =1;
	if(C1 == 0)
	{
		while(C1 == 0);
		key_num = 8;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C2 == 0)
	{
		while(C2 == 0);
		key_num = 9;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C3 == 0)
	{
		while(C3 == 0);
		key_num = 10;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C4 == 0)
	{
		while(C4 == 0);
		key_num = 11;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	
	R4 = 0;
	R2 = R3 = R1 = 1;
	C1 = C2 = C3 = C4 =1;
	if(C1 == 0)
	{
		while(C1 == 0);
		key_num = 12;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C2 == 0)
	{
		while(C2 == 0);
		key_num = 13;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C3 == 0)
	{
		while(C3 == 0);
		key_num = 14;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
	else if(C4 == 0)
	{
		while(C4 == 0);
		key_num = 15;
		DisplayKeyNum(SMG_duanma[key_num]);
	}
}
 
void main()
{
	while(1)
	{
		ScanKeysMulti();
	}
}

注意：由于这里使用的是"reg52.h"头文件，而它没有P4端口的内存地址，所以要加上sfr P4    = 0xC0;或者使用#include "STC15F2K60S2.H"头文件

烧录进单片机后就能看到现象了