C51音乐倒数计数器题目要求：利用AT89C51单片机结合字符型LCD显示器设计一个简易的倒数计数器，可用来煮方便面、煮开水或小睡片刻等。
做一小段时间倒计数，当倒计数为0时，则发出一段音乐声响，通知倒计数终了，该做应当做的事。
定时闹钟的基本功能如下。
字符型LCD（16 ´ 2）显示器。
显示格式为“TIME 分分:秒秒”。
用4个按键操作来设置当前想要倒计数的时间。
一旦按下键则开始倒计数，当计数为0时，发出一阵音乐声。
程序执行后工作指示灯LED闪动，表示程序开始执行，按下操作键K1～K4动作如下。
K1—可调整倒计数的时间1～60分钟。
K2—设置倒计数的时间为5分钟，显示“0500”。
K3—设置倒计数的时间为10分钟，显示“1000”。
K4—设置倒计数的时间为20分钟，显示“2000”。
复位后LCD的画面应能显示倒计时的分钟和秒数，此时按K1键运行截图程序代码：#include<reg51.h>#define uchar unsigned char#define uint unsigned int#define busy 0x80sbit k1=P1^0;sbit k2=P1^1;sbit k3=P1^2;sbit k4=P1^3;sbit k5=P1^4;sbit RS=P2^5;sbit RW=P2^6;sbit E=P2^7;sbit led=P2^0;sbit sound=P3^7;uchar code tableee[]=" 20:00 20:00";uchar code tablee[]=" 10:00 10:00";uchar code table[]=" 05:00 05:00";uchar code table1[]={'0','1','2','3','4','5','6','7','8','9'};uchar code table3[]="14 dao ji shi";uchar code table2[]="888888888888";uchar code table5[]=" 05:00";uchar code table4[]=" TIME OUT! ";uchar d,e,num,t,shishi,shige,fenshi,fenge,miaoshi,miaoge,b,b1,a,aa;uint counter=0;uchar code array[]= {0x18, 0x30, 0x1C, 0x10, 0x20, 0x40, 0x1C, 0x10,0x18, 0x10, 0x20, 0x10, 0x1C, 0x10, 0x18, 0x40,0x1C, 0x20, 0x20, 0x20, 0x1C, 0x20, 0x18, 0x20,0x20, 0x80, 0xFF, 0x20, 0x30, 0x1C, 0x10, 0x18,0x20, 0x15, 0x20, 0x1C, 0x20, 0x20, 0x20, 0x26,0x40, 0x20, 0x20, 0x2B, 0x20, 0x26, 0x20, 0x20,0x20, 0x30, 0x80, 0xFF, 0x20, 0x20, 0x1C, 0x10,0x18, 0x10, 0x20, 0x20, 0x26, 0x20, 0x2B, 0x20,0x30, 0x20, 0x2B, 0x40, 0x20, 0x20, 0x1C, 0x10,0x18, 0x10, 0x20, 0x20, 0x26, 0x20, 0x2B, 0x20,0x30, 0x20, 0x2B, 0x40, 0x20, 0x30, 0x1C, 0x10,0x18, 0x20, 0x15, 0x20, 0x1C, 0x20, 0x20, 0x20,0x26, 0x40, 0x20, 0x20, 0x2B, 0x20, 0x26, 0x20,0x20, 0x20, 0x30, 0x80, 0x20, 0x30, 0x1C, 0x10,0x20, 0x10, 0x1C, 0x10, 0x20, 0x20, 0x26, 0x20,0x2B, 0x20, 0x30, 0x20, 0x2B, 0x40, 0x20, 0x15,0x1F, 0x05, 0x20, 0x10, 0x1C, 0x10, 0x20, 0x20,0x26, 0x20, 0x2B, 0x20, 0x30, 0x20, 0x2B, 0x40,0x20, 0x30, 0x1C, 0x10, 0x18, 0x20, 0x15, 0x20,0x1C, 0x20, 0x20, 0x20, 0x26, 0x40, 0x20, 0x20,0x2B, 0x20, 0x26, 0x20, 0x20, 0x20, 0x30, 0x30,0x20, 0x30, 0x1C, 0x10, 0x18, 0x40, 0x1C, 0x20,0x20, 0x20, 0x26, 0x40, 0x13, 0x60, 0x18, 0x20,0x15, 0x40, 0x13, 0x40, 0x18, 0x80, 0x00};char shi,fen,miao;void LCD_init();bit lcd_busy();void write_1602cmd(uchar cmd); //写命令void write_1602Data(uchar Data); //写数据void sound_delay(uchar n);void playmusic();void delay(uchar z);void init(){t=0,led=1;TMOD=0X11; //设置定时器0,置定时器1在工作方式1 TH0=0xff;TL0=0xff;TH1=(65536-50000)/256; //给定时器1装初值TL1=(65536-50000)%256;EA=1; //开启总中断ET0=1; // 开启外部中断0中断ET1=1;// 开启定时器1中断TR0=0;TR1=0;LCD_init();write_1602cmd(0x80);for(num=0;num<14;num++){write_1602Data(table3[num]);delay(5);}write_1602cmd(0x80+0x40);for(num=0;num<12;num++){write_1602Data(table2[num]);delay(5);}}void key_check(){if(k2==0) //5min{delay(10);if(k2==0){for(num=0;num<12;num++){write_1602Data(table[num]);delay(5);}TR1=1;fen=5;miao=0;}}if(k3==0) //10min{delay(10);if(k3==0){write_1602cmd(0x80+0x40);for(num=0;num<12;num++){write_1602Data(tablee[num]);delay(5);}TR1=1;fen=10;miao=0;}}if(k4==0) //20min{delay(10);if(k4==0){write_1602cmd(0x80+0x40);for(num=0;num<12;num++){write_1602Data(tableee[num]);delay(5);}TR1=1;fen=20;miao=0;}}if(k1==0){delay(10);if(k1==0){for(num=0;num<12;num++){write_1602Data(table5[num]);delay(5);}fen = 5;while(k4 != 0){if(k2==0){delay(10);if(k2==0){fen++;fenge=fen%10;fenshi=fen/10;write_1602cmd(0x80+0x40+2);write_1602Data(table1[fenge]);write_1602cmd(0x80+0x40+1);write_1602Data(table1[fenshi]);write_1602cmd(0x0f); //打开光标闪烁while(k2==0);}}if(k3==0){delay(10);if(k3==0){fen--;fenge=fen%10;fenshi=fen/10;write_1602cmd(0x80+0x40+2);write_1602Data(table1[fenge]);write_1602cmd(0x80+0x40+1);write_1602Data(table1[fenshi]);write_1602cmd(0x0f); //打开光标闪烁while(k3==0);}}}TR1=1;write_1602cmd(0x0c); //关闭光标闪烁}}}void main(){a=0,aa=0,d=0;e=0;init();delay(100);while(1){if(TR1 == 0) key_check();while(TR0==1&&TR1==0){playmusic();}}}void time1() interrupt 3 //定时器1中断{TH1=(65536-50000)/256;TL1=(65536-50000)%256;a++;aa++;if(a==20) //定时达到1s{a=0;if(fen==0 && miao==0) //到达了指定时间{TR1=0;TR0=1;led=0;write_1602cmd(0x80+0x40);for(num=0;num<15;num++){write_1602Data(table4[num]);delay(5);goto end; //直接跳出定时器中断}if(miao==0){miao = 59;fen--;fenge=fen%10;fenshi=fen/10;write_1602cmd(0x80+0x40+8);write_1602Data(table1[fenge]);write_1602cmd(0x80+0x40+7);write_1602Data(table1[fenshi]);}miaoge = miao%10;miaoshi = miao/10;write_1602cmd(0x80+0x40+11);write_1602Data(table1[miaoge]);write_1602cmd(0x80+0x40+10);write_1602Data(table1[miaoshi]);miao--;}if(aa==10) //开启流水灯，让它随时间的流动{aa=0;led=~led;write_1602cmd(0x80+0x40+9);if(led ==1){write_1602Data(':');}else{write_1602Data(' ');}}end: //结束了直接跳到这里来;}//********************************************* void delay(uchar z){uchar x,y;for(x=z;x>0;x--)for(y=200;y>0;y--);}bit lcd_busy() //测试LCD忙碌状态{bit result;E= 0;RS= 0; //指令RW= 1; //读出E= 1;delay(4);//高电平读出1usresult = (bit)(P0 & busy);E= 0;return result;}void write_1602cmd(uchar cmd) //写命令{while(lcd_busy());RS=0;delay(5);RW=0;delay(5);E=0;delay(5);P0=cmd;E=1;delay(10);E=0;}void write_1602Data(uchar Data) //写数据{while(lcd_busy());RS=1;delay(5);RW=0;delay(5);E=0;P0=Data;delay(5);E=1;delay(10);E=0;}//lcd初始化void LCD_init(){write_1602cmd(0x01); //清屏delay(5);write_1602cmd(0x38); //功能设定delay(5);write_1602cmd(0x0c); //光标不闪烁delay(5);write_1602cmd(0x06); //lcd模式设定，delay(5);}void sound_delay(uchar n){uchar i;while(n--){for(i=0;i<2;i++);}}void time0() interrupt 1 //定时器0中断{counter=counter+1;//节拍次数计数TH0=0xd8; //定义单位节拍的延时大小TL0=0xef;}void playmusic(){uint i;uchar sound_signal;//定义音符大小uchar sound_pace;while(1){i=0;while(array[i]!=0x00){ //如果是休止符，延时100ms，并终止本次循环，进入下一个循环if(array[i]==0xff){TR0=0;i++;delay(100);continue;} //从表中取得音符?sound_signal=array[i];i=i+1; //从表中取得节拍大小sound_pace=array[i];TR0=1; //当节拍数未达到时候，继续循环，产生该音调的声音while(counter!=sound_pace){sound=~sound;sound_delay(sound_signal);}i++;counter=0;//节拍计数器置0，进入下一个?}delay(10); //歌曲演唱完毕后,延时一段时间}}Proteus 仿真图：。
