main.c

从零开始学51单片机源代码

//main.c
#include <reg51.h>	//包含头文件

 //定义端口寄存器
sfr P0M0 = 0X93;
sfr P0M1 = 0X94;
sfr P1M0 = 0X91;
sfr P1M1 = 0X92;
sfr P2M0 = 0X95;
sfr P2M1 = 0X96;  
sfr P3M0 = 0Xb1;
sfr P3M1 = 0Xb2; 

/*
共阴极数码管0 - F的字形码 
"0" 3FH  "8" 7FH  
"1" 06H  "9" 6FH
"2" 5BH  "A" 77H
"3" 4FH  "b" 7CH
"4" 66H  "C" 39H
"5" 6DH  "d" 5EH
"6" 7DH  "E" 79H
"7" 07H   "F" 71H
*/
const unsigned char seg7[10] = { 0x3f, 0x06, 0x5b, 0x4f, 0x66, 
								0x6d, 0x7d, 0x07, 0x7f, 0x6f };  

//定义端口 
sbit car_in = P1^0;
sbit car_out = P1^1;
sbit en1 = P2^6;
sbit en2 = P2^7;

//定义延时函数
void ms_delay(unsigned int t)
{
	unsigned  int  i;
	for (t; t > 0; t--)	//外层循环t次	 
		for (i = 110;i > 0; i--)	//内层循环110次		   
		;
}  

//定义数码管显示函数 
void display(int n)
{
	char b2,b1;

	b2 = n / 10;
	b1 = n % 10;

	//十位
	P0 = seg7[b2];	
	en2 = 0;	//显示DS2
	ms_delay(10);
	en2 = 1;	//关闭DS2	

	//个位
	P0 = seg7[b1];
	en1 = 0;	//显示DS1
	ms_delay(10);
	en1 = 1;	//关闭DS1

}

main()
{
	int num = 99;

	//配置端口模式 
	P0M1 = 0xff;
	P0M0 = 0xff;
	P1M1 = 0x03;
	P1M0 = 0x00;

	display(num); //刚开始显示总车位99

	while(1)
	{
		//car_in 
	 	if (car_in == 0)	//如果s1被按下 
		{
		 	ms_delay(10);  //延时消抖 
			if (car_in == 0)
			{
			   num -- ; //车位减一
			}
		}	

		//car_out 
		if (car_out == 0)	//如果s2被按下 
		{
		 	ms_delay(10);  //延时消抖 
			if (car_out == 0)
			{
			   num ++; //车位加一
			}
		}	

		 //合理性判断 
		 if (num > 99)
		 {
		 	num = 99;
		 }
		 else if ( num < 0)
		 {
		  	num = 0;
		 }

		 display(num);//显示 
	}
}