KST51 single-chip microcomputer: realize the detection and debounce of the number of matrix keys through interrupt

Take Key4 as an example, use a timer interrupt of 2ms to debounce, and judge the key state for 8 consecutive times (16ms).

If all are 1, it will pop up , and the current state of the key (Keysta) will be 1;

If all are 0, press it , and set the current state of the key (Keysta) to 0;

The other states are shaking, and the current state of the button remains unchanged .

The key status is judged in the main program. If the current key status (Keysta) is different from the key historical status (backup), it means that the key status has changed . In the program, when the system pops up, the number of key presses changes, and the latest number of key presses is sent to the digital tube for display, and the historical key state is updated to the current state and the next judgment is made. The source code is as follows:

#include<reg52.h>

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

bit KeySta = 1;           //位定义

void main()
{
	bit backup = 1;       //定义一个位变量，保存前一次扫描的按键值。
	unsigned char cnt = 0;

	EA = 1;
	ENLED = 0;            //使能U3 选中数码管DS1
	ADDR3 = 1;			
	ADDR2 = 0;
	ADDR1 = 0;
	ADDR0 = 0;
	TMOD = 0x01;          //T0为模式1
	TH0 = 0xf8;           //定时2ms
	TL0 = 0xcd;
	ET0 = 1;
	TR0 = 1;              //启动T0
	P2 = 0xf7;            //P2.3置0，即输出低电平
	P0 = LedChar[cnt];    //显示按键次数
	
	while(1)
	{
		if(KeySta != backup)         //当前值与前次值不相等说明此时有动作
		{
			if(backup == 0)          //如果前次值为0，则说明是弹起动作
			{
				cnt++;               //按键次数加1
				if(cnt >= 10)
				{
					cnt = 0;         //10次清0
				}
 				P0 = LedChar[cnt];
			}
			backup = KeySta;         //更新备份为当前值
		}

	}
}
/*T0中断服务函数，用于按键状态的扫描并消抖*/
void InterruptTimer0() interrupt 1
{
	static unsigned char keybuf =0xff;  //扫描缓冲区，保存一段时间内的扫描值
	TH0 = 0xf8;                         //重新加载初值
	TL0 = 0xcd;
	keybuf= (keybuf<<1) |KEY4;          //缓冲区左移一位，并将当前扫描值移入最低位
	if(keybuf == 0x00)                  //连续8次扫描值都为0，16ms内状态不变，即按键已按下
	{
		KeySta = 0;
	}
	else if(keybuf == 0xff)             //连续8次扫描值都为1，16ms内状态不变，即按键已弹起
	{
		KeySta = 1;
	}
	else                                //其他情况则按键状态还未稳定
	{}	
}