C51-------时钟程序（C语言编写的单片机时钟）

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作者：罗国辉

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 这是我大二的时候第一次学单片机的时候写的第一个程序，后面大三的时候，我们专业才开单片机的课程，又真正系统的学习了一遍，才算是真正对单片掌握了，对我后面的嵌入式开发做了一定的铺垫。不过，建议学单片的读者，一开始不要用C语言去写，一开始最好是用汇编去写程序，这样子，对51片子的一些东西可以更好的理解。

1.原理图：

2.程序：

 

#include<reg52.h>#include<absacc.h>#include<math.h>#include<stdio.h>#define LEDcom0 XBYTE[0x4ff0]#define LEDcom1 XBYTE[0x4ff1]#define LEDcom2 XBYTE[0x4ff2]#define LEDcom3 XBYTE[0x4ff3]#define LEDcom4 XBYTE[0x4ff4]#define LEDcom5 XBYTE[0x4ff5]#define LEDcom6 XBYTE[0x4ff6]#define LEDcom7 XBYTE[0x4ff7]#define keycom XBYTE[0x2fff]#define HI ((65536 - 50000) / 256)#define LO ((65536 - 50000) % 256)#define _TH0_TL0_ (65536 - 50000)#define M 20 //中断次数unsigned char code SEG_TAB_A[10] = {0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f}; //0-9码码值unsigned char code SEG_TAB_B[10] = {0xbf,0x86,0xdb,0xcf,0xe6,0xed,0xfd,0x87,0xff,0xef}; //0.-9.码值static unsigned char hou = 12, min = 0, sec = 0;unsigned char keyflag=0,keyflag2=0;void keynum(void);void readkey0(void);void readkey1(void);void readkey2(void);void readkey3(void);void readkey4(void);void readkey5(void);void readkey6(void);void readkey7(void);void Timer0(void) interrupt 1 using 1 //T/C0中断服务程序，定时50ms{ static unsigned char count = 0; //定义静态变量count，中断记数 TR0 = 0; TL0 += (_TH0_TL0_ + 9) % 256; TH0 += (_TH0_TL0_ + 9) / 256 + (char)CY; TR0 = 1; count++; if(keycom==0xfd) { keynum(); } if(count == M) { count = 0; sec++; if(sec == 60) { min++; sec = 0; if(min == 60) { hou++; min = 0; if(hou == 24) { hou = 0; }//if hou=24 }//if min=60 }//if sec=60 }//if count=M}void Timer0Init(void) //定时器0{ TMOD = 0x01; TH0 = HI; //载入高8位初值 TL0 = LO; //载入低8位初值 TR0 = 1; //启动定时器 EA = 1; //开总中断 ET0 = 1; //开定时器中断.若为0则表示关闭}void Delay(unsigned char a)//延时a*1MS{ unsigned char j; while(a-- != 0) { for (j = 0; j < 125; j++); }}int pkey(void)//判断键是否被按下，通过返回值确定{ if(keycom!=0xff) { Delay(200); if(keycom!=0xff) return 1; else return 0; } else return 0;}void keynum(void)//按键确定{ keyflag2=1; TR0 = 0;//定时器关闭 EA = 0;//总中断关闭 ET0 = 0;//定时器中断关闭 while(keyflag2) { //Delay(500000); if(pkey()==1) { switch(keycom) { case 0x7f: { readkey0();} break; case 0xbf: { readkey1();} break; case 0xdf: { readkey2();} break; case 0xef: { readkey3();} break; case 0xf7: { readkey4();} break; case 0xfb: { readkey5();} break; default: break; } } readkey7(); }}/*-----时间调整------- 1=hour+ ; 2=minute+ ; 3=second+ ;4=hour- ;5=minute- ; 6=second------------------------*/void readkey0(){ while(keycom==0x7f) {keyflag=1;} if(hou==24) { hou=0; } hou++;}void readkey1(){ while(keycom==0xbf) {keyflag=2;} if(min==60) { min=0; } min++;}void readkey2(){ while(keycom==0xdf) {keyflag=3;} if(sec==60) { sec=0; } sec++;}void readkey3(){ while(keycom==0xef) {keyflag=4;} if(hou==0) { hou=24; } hou--;}void readkey4(){ while(keycom==0xf7) {keyflag=5;} if(min==0) { min=24; } min--;}void readkey5(){ while(keycom==0xfb) {keyflag=6;} if(sec==0) { sec=24; } sec--;}/*unsigned char readkey6(){ while(keycom==0xfe) {keyflag=6;} key6++; if(key7>9) { key7=0; } }*/void readkey7(){ while(keycom==0xfe) {keyflag=8;} keyflag2=0;//退出时间调整,置0 /*中断重启*/ TL0 += (_TH0_TL0_ + 9) % 256; TH0 += (_TH0_TL0_ + 9) / 256 + (char)CY; TR0 = 1; EA = 1; ET0 = 1;}void Disp(void)//数码管显示函数{ LEDcom0 = SEG_TAB_A[ hou / 10 ]; LEDcom1 = SEG_TAB_A[ hou % 10 ]; LEDcom2 = 0x40; LEDcom3 = SEG_TAB_A[ min / 10 ]; LEDcom4 = SEG_TAB_A[ min % 10 ]; LEDcom5 = 0x40; LEDcom6 = SEG_TAB_A[ sec / 10 ]; LEDcom7 = SEG_TAB_A[ sec % 10 ]; }void main(void) //主函数{ keycom=1; Timer0Init(); while(1) { Disp(); }}--------------------------------------3.问题：键盘无反应，请教！－－－－－－－－－－－－－－－4.答案：调试了一下，结果发现了错误原因：由于按鍵等待时间太少，故readkey7()一进入循环就执行，根本就不能处理其它按鍵，所以只需把readkey7()放到switch()里面即可，用7的键值来确定退出！－－－－－－－－－－－－－－－－－罗国辉　　2007.6.21－－－－－－－－－－－－－－－－－－－－－－－while(keyflag2) { //Delay(5000000); if(pkey()==1) { switch(keycom) { case 0x7f: { readkey0();} break; case 0xbf: { readkey1();} break; case 0xdf: { readkey2();} break; case 0xef: { readkey3();} break; case 0xf7: { readkey4();} break; case 0xfb: { readkey5();} break; default: { readkey7();} break; } }