8051单片机(STC89C52)以定时器中断模式实现倒计时器

╰半夏微凉° 2021-12-10 05:43 480阅读 0赞

之前用轮询方式实现了定时器精准定时, 这里用前后台系统架构实现倒计时器.

每10ms都会触发一次中断处理程序T0\_INT(), 根据tcount的值, 决定显示个位数字还是十位数字: 当tcount = 100时, 将tcount置回初始值0, 并将sec的值减1. 当sec的值减到-1时, 将sec重新置回15.

#include <STC89C5xRC.H>
    
    unsigned char code DIG_CODE[10] = {0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07, 0x7f, 0x6f};//对应数码管显示0~9
    
    int tcount = 0;//记录经过的10ms区间段个数
    
    int sec = 15;//倒计时初始值
    
    void T0_INT() interrupt 1 //timer0中断, 每10ms触发一次
    {
    	TR0 = 0;//关闭timer0
    	TH0 = 0xD8;
    	TL0 = 0xF0;//65536 - 10000 = 55536
    	if(tcount % 2 == 0)
    	{
    		//显示个位数
    		P2 = 0;// P2 = 0 -> (P24, P23, P22) = (0, 0, 0) -> 右数第一个数字点亮
    		P0 = DIG_CODE[sec % 10];
    		tcount ++;
    	}
    	else if(tcount % 2 == 1)
    	{
    		//显示十位数
    		P2 = 1 << 2;//P2 = 0000 0100 -> (P24, P23, P22) = (0, 0, 1) -> 右数第二个数字点亮
    		P0 = DIG_CODE[sec / 10];
    		tcount ++;
    	}
    	if(tcount == 100) //10ms * 100 = 1000ms = 1s -> 1s时间到
    	{
    	 	tcount = 0;
    		sec --;
    		if(sec == -1)
    		{
    			sec = 15;
    		}
    	}
    	TR0 = 1;//重新开启timer0
    }
     
    int main()
    {
    	TMOD = 0x01;
    	TH0 = 0xD8;
    	TL0 = 0xF0;//65536 - 10000 = 55536
    	IE = 0x82;//EA + ET0 -> 1000 0010
    	TR0 = 1;//开启timer0
    	while(1)
    	{
    		;
    	}
    	return 0;
    }

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