8051单片机(STC89C52)实现可修改初值(并可命令启停)的单倒计时器(Version1.2)

￡神魔★判官ぃ 2021-12-09 03:47 203阅读 0赞

较Version1.1, 此处通过string.h文件中的strcmp()函数简化了对简单命令的判断.

#include <STC89C5xRC.H>
    
    #include <string.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[30];
    
    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 = 0;//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 = 0;//暂不开启timer0
    	TR1 = 1;//开启timer1
    	while(1)
    	{
    		if(RI == 1)//收到数据
    		{
    			RI = 0;
    			buf[i ++] = SBUF;//接收串口发来的数据
    			buf[i] = '\0';//手动添加字符串结束标志
    			if(i == 29)//防止数组访问越界
    			{
    				i = 0;
    			}
    			if(buf[i - 1] == 'E')//到达结尾
    			{
    				i = 0;
    				if(strcmp(buf, "Start.E") == 0)//Start.命令
    				{
    					TR0 = 1;//启动timer0 -> 开启倒计时器
    				}
    				else if(strcmp(buf, "Stop.E") == 0)
    				{
    					TR0 = 0;//关闭timer0 -> 暂停倒计时器
    				}
    				else if(buf[0] == 'S' && buf[1] == 'e' && buf[2] == 't' && buf[3] == ' ' && 
    						buf[4] == 'i' && buf[5] == 'n' && buf[6] == 'i' && buf[7] == 't' && 
    						buf[8] == ' ' && buf[9] == 'v' && buf[10] == 'a' && buf[11] == 'l' && 
    						buf[12] == 'u' && buf[13] == 'e' && buf[14] == ' ' && buf[15] == 'a' && buf[16] == 's' && buf[17] == ' ' && buf[20] == '.')
    				{
    					sec = (buf[18] - 48) * 10 + (buf[19] - 48);
    				}
    			}
    		}
    	}
    	return 0;
    }