8051单片机(STC89C52)实现可修改计时初值的单倒计时器(Version1.0)

太过爱你忘了你带给我的痛 2021-12-10 06:31 413阅读 0赞

程序启动后计时初值为15, 之后可通过串口发来的数据(如"99")来修改下一次计时初值.

#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 
    
    char buf[2];
    
    int tcount = 0;//记录经过的10ms区间段个数
    
    int sec = 15;//倒计时初始值记录
    
    int sec2 = 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[sec2 % 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[sec2 / 10];
    		tcount ++;
    	}
    	if(tcount == 100) //10ms * 100 = 1000ms = 1s -> 1s时间到
    	{
    	 	tcount = 0;
    		sec2 --;
    		if(sec2 == -1)
    		{
    			sec2 = sec;
    		}
    	}
    	TR0 = 1;//重新开启timer0
    }
    
    int main()
    {
    	int i = 0;
    	TMOD = 0x21;
    	SCON = 0x50;//设置串行通信格式
    	TH0 = 0xD8;
    	TL0 = 0xF0;//65536 - 10000 = 55536
    	IE = 0x82;//EA + ET0 -> 1000 0010
    	TH1 = 0xE6;
    	TL1 = 0xE6;//1200bps under 12MHz
    	RI = 0;
    	TR0 = 1;//开启timer0
    	TR1 = 1;//开启timer1
    	while(1)
    	{
    		if(RI == 1)
    		{
    			RI = 0;
    			buf[i++] = SBUF;//接收串口发来的数据
    			if(i == 2)
    			{
    				i = 0;
    				sec = (buf[0] - 48) * 10 + (buf[1] - 48);
    			}
    		}
    	}
    	return 0;
    }