单片机矩阵键盘

矩阵键盘原理就是
如果键盘没有弹起来
判断一下backup是不是为0，
这样判断是为了能够本身backup不是0，进不去
加上了一句把key的值赋给backup，如果不加上判断的话，就会重复走两次程序，按下一次，松开一次
这样是为了一次只能计数一次
如果按下
那就是计数并且给数码管+1
同时，计数的值需要判断如果已经是10次了，那就直接清零
#include

sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;

sbit LED9 = P0^7;
sbit LED8 = P0^6;
sbit LED7 = P0^5;
sbit LED6 = P0^4;

sbit KEY4 = P2^7;

unsigned char code LedChar[]={
0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8,
0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E
};

void main()
{
bit backup = 1;
unsigned char cnt = 0;

ENLED = 0;
ADDR3 = 1;
ADDR2 = 0;
ADDR1 = 0;
ADDR0 = 0;
P2 = 0xF7;
P0 = LedChar[cnt];

while(1)
{
	if(KEY4 != backup)
	{
		if(backup == 0)
		{
			cnt++;
			if(cnt >= 10)
			{
				cnt = 0;
			}
			P0 = LedChar[cnt];
		}
		backup = KEY4;
	}

}

如果关键代码改成这个样子
每一次按键都会计数两次
原因是因为在按下和松开的时候
代码都执行了一次，所以我们能看都代码直接执行了两次
#include

sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;

sbit LED9 = P0^7;
sbit LED8 = P0^6;
sbit LED7 = P0^5;
sbit LED6 = P0^4;

sbit KEY1 = P2^4;
sbit KEY2 = P2^5;
sbit KEY3 = P2^6;
sbit KEY4 = P2^7;

unsigned char code LedChar[]={
0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8,
0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E
};

void main()
{
bit down = 0;
/*这里为什么用bit这是一个特殊的关键字
这个关键字只有0和1两个值
*/
unsigned char cnt = 0;
ENLED = 0;
ADDR3 = 1;
ADDR2 = 0;
ADDR1 = 0;
ADDR0 = 0;
P2 = 0xF7;
P0 = LedChar[cnt];

while(1)
{
	if(KEY4 == down)
	{			
		cnt++;	
			if (cnt >= 10)
			{
				cnt = 0;
			}
		P0 = LedChar[cnt];		 	
		 down = ~KEY4;	//为什么取反，是为了能让程序当次结束
	}
	
}

}
按键消抖动
按键过程会存在10ms以内，按下和弹起的过程中出现抖动，造成会出现值得偏差，可以硬件解决也可以软件解决，但是软件解决的成本低，并且实用

消除抖动
程序执行现象应该是按下一直按住数码管不会变化，一松手自动+1
消抖 就是找一个中间变量 keybuf 用来一直记录key的值，再加上10ms
延时，通过延时前后两次判断值是不是相等，确实抖动应该消除了，然后再执行

#include

sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;

sbit LED9 = P0^7;
sbit LED8 = P0^6;
sbit LED7 = P0^5;
sbit LED6 = P0^4;

sbit KEY1 = P2^4;
sbit KEY2 = P2^5;
sbit KEY3 = P2^6;
sbit KEY4 = P2^7;

unsigned char code LedChar[]={
0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8,
0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E
};
void delay();
void main()
{
bit backup = 1;
unsigned char cnt = 0;
unsigned char keybuf = 0;
ENLED = 0;
ADDR3 = 1;
ADDR2 = 0;
ADDR1 = 0;
ADDR0 = 0;
P2 = 0xF7;
P0 = LedChar[cnt];

while(1)
{
	keybuf = KEY4;
	if(keybuf != backup )
	{
		delay();
		if(KEY4 == keybuf)
		{		
			if(backup == 0)
			{
				cnt++;
				if(cnt >= 10)
				{
					cnt = 0;
				}
				P0 = LedChar[cnt];
				
			}
			backup = keybuf;
		}				
	} 
}

}
void delay()
{
unsigned int i = 1000;
while(i–);
}