51单片机入门程序——秒表程序示例

下午自学了一下单片机的前几章的知识，理解了数码管的显示原理以及静态显示和动态扫描的编程方法。其中，比较重要的几个概念有：数码管公共端类型(共阴极、共阳极)、位选(决定多位数码管中哪一位显示)、段选(决定数码管显示的数字)，另外还有锁存器(教材P36，可通过控制锁存端来改变数据输出的状态)。

上周单片机实验课的内容是编一个秒表，在4位数码管中分别显示分和秒还有分秒，即最多可显示“9:59.9”。这里我用两个键实现了秒表的启动/暂停和清零功能，代码如下：

#include <reg51.h>#define uint unsigned int#define uchar unsigned charsbit S1 = P1^3;sbit S2 = P1^1;sbit S3 = P1^2;sbit S4 = P1^0;sbit beep = P2^7;sbit a = P0^0;sbit b = P0^1;sbit c = P0^2;sbit d = P0^3;sbit e = P0^4;sbit f = P0^5;sbit g = P0^6;sbit p = P0^7;sbit key1 = P1^4;sbit key2 = P1^5;sbit key3 = P3^6;sbit key4 = P3^7;uchar num,kms,sec,min;uchar code N[10] = {0xc0, 0xf9 ,0xa4, 0xb0, 0x99, 0x92, 0x82, 0xf8, 0x80, 0x90}; //0, 1, 2, 3, ...8, 9uchar code Z[10] = {0x40, 0x79 ,0x24, 0x30, 0x19, 0x12, 0x02, 0x78, 0x00, 0x10}; //0., 1., 2., ... 8., 9.void delayms(uint xms){uint i,j;for(i = xms; i > 0; i--)for(j = 110; j > 0; j--);}void init(){TMOD = 0x01;TH0 = 0x3c;TL0 = 0xb0;S3 = 1;S1 = S2 = S4 = 0;P0 = N[0];delayms(5);S3 = 0;S1 = S2 = S4 = 1;P0 = Z[0];delayms(5);EA = 1;TR0 = 0;ET0 = 1;kms = sec = min = 0;}void display(){uchar shi, ge;if(kms >= 0){S4 = 0;S1 = S2 = S3 = 1;P0 = N[kms];}delayms(5);if(sec >= 0){shi = sec/10;ge = sec%10;S3 = 0;S1 = S2 = S4 = 1;P0 = Z[ge];delayms(5);S2 = 0;S1 = S3 = S4 = 1;P0 = N[shi];}delayms(5);if(min >= 0){S1 = 0;S2 = S3 = S4 = 1;P0 = N[min];}delayms(5);}void keyscan(){if(key1 == 0){delayms(10);if(key1 == 0){while(!key1);TR0 = ~TR0;}}if(key2 == 0){delayms(10);if(key2 == 0){min = sec = kms = 0;while(!key1);}}}main(){init();while(1){keyscan();display();}}void T0_time() interrupt 1{TH0 = 0x3c;TL0 = 0xb0;num++;if(num == 2){num = 0;kms++;if(kms == 10){kms = 0;sec++;if(sec == 60){sec = 0;min++;if(min == 10){TR0 = 0;min = 9;sec = 59;kms = 9;}}}}} 

程序通过“Keil uVision4”调试，大家也可以在板子上运行一下试试。

注意：需要根据板子的端口定义相关变量，不要不分青红皂白就直接使用我的程序哈。

最后上个图，第一次做单片机，希望以后还有时间可以做更深入的更好玩的东西。