单片机数字音乐盒设计

ID:1055121 · 发表于 2022-12-21 11:15

单片机数字音乐盒制作proteus仿真原理图：

单片机源程序：

#include<reg51.h>
#define uchar unsigned char
#define uchar unsigned char
#define uint unsigned int
#define LCDPORT P0
uchar code tab[]="Press key";
uchar code tab1[]="Select song";
uchar code tab2[]="First Song" ;
uchar code tab3[]="butterfly";
uchar code tab4[]="Second Song" ;
uchar code tab5[]="Jingle bell ";
uchar code tab6[]="Third Song" ;
uchar code tab7[]="Yesterday";
uchar code tab8[]="Forth Song" ;
uchar code tab9[]="Youth League";
sbit LCDE=P2^2;
sbit LCDRW=P2^1;
sbit LCDRS=P2^0;
#define SYSTEM_OSC 12000000 //定义晶振频率12000000HZ
#define SOUND_SPACE 4/5 //定义普通音符演奏的长度分率,//每4分音符间隔
sbit BeepIO = P3^7; //定义输出管脚
sbit K1=P1^7;
unsigned int code FreTab[12] = { 262,277,294,311,330,349,369,392,415,440,466,494 }; //原始频率表
unsigned char code SignTab[7] = { 0,2,4,5,7,9,11 }; //1~7在频率表中的位置
unsigned char code LengthTab[7]= { 1,2,4,8,16,32,64 };
unsigned char Sound_Temp_TH0,Sound_Temp_TL0; //音符定时器初值暂存
unsigned char Sound_Temp_TH1,Sound_Temp_TL1;
unsigned char code Music_Girl[]=
{ 0x1B,0x02, 0x1A,0x02, 0x1B,0x02, 0x19,0x66, 0x1A,0x03,
0x18,0x02, 0x17,0x02, 0x16,0x0D, 0x17,0x03, 0x18,0x0D,
0x17,0x03, 0x19,0x66, 0x17,0x03, 0x16,0x0D, 0x17,0x03,
0x19,0x0D, 0x16,0x03, 0x17,0x0D, 0x18,0x03, 0x17,0x0D,
0x16,0x03, 0x15,0x00, 0x19,0x02, 0x11,0x02, 0x16,0x02,
0x10,0x02, 0x15,0x02, 0x0F,0x00, 0x10,0x03, 0x15,0x03,
0x0F,0x00, 0x0D,0x01, 0x0F,0x66, 0x10,0x03, 0x15,0x66,
0x16,0x03, 0x10,0x0D, 0x15,0x03, 0x0F,0x03, 0x19,0x66,
0x1F,0x03, 0x1A,0x0D, 0x19,0x03, 0x17,0x03, 0x19,0x03,
0x16,0x00, 0x16,0x66, 0x17,0x03, 0x11,0x0C, 0x10,0x02,
0x19,0x66, 0x10,0x03, 0x15,0x02, 0x16,0x02, 0x0D,0x02,
0x15,0x02, 0x10,0x0D, 0x0F,0x03, 0x10,0x0D, 0x15,0x03,
0x0F,0x00, 0x17,0x66, 0x19,0x03, 0x11,0x02, 0x16,0x02,
0x10,0x0D, 0x15,0x03, 0x0F,0x15, 0x0D,0x03, 0x0F,0x02,
0x0D,0x03, 0x0F,0x0D, 0x10,0x03, 0x11,0x0D, 0x16,0x03,
0x10,0x00, 0x0F,0x0D, 0x10,0x03, 0x15,0x66, 0x16,0x03,
0x19,0x02, 0x17,0x02, 0x16,0x02, 0x17,0x0D, 0x16,0x03,
0x15,0x02, 0x10,0x0D, 0x0F,0x03, 0x0D,0x01, 0x15,0x01,
0x10,0x03, 0x15,0x04, 0x10,0x0D, 0x0F,0x03, 0x0D,0x0D,
0x0F,0x03, 0x10,0x0D, 0x15,0x03, 0x0F,0x00, 0x17,0x0D,
0x19,0x03, 0x16,0x0D, 0x17,0x03, 0x16,0x0D, 0x15,0x03,
0x11,0x02, 0x10,0x02, 0x0F,0x00, 0x00,0x00 };
unsigned char code Music_Jingle[]={
0x0F,0x03, 0x0F,0x03, 0x17,0x03, 0x16,0x03, 0x15,0x03,
0x0F,0x66, 0x19,0x04, 0x19,0x04, 0x0F,0x03, 0x17,0x03,
0x16,0x03, 0x15,0x03, 0x10,0x02, 0x10,0x03, 0x10,0x03,
0x18,0x03, 0x17,0x03, 0x16,0x03, 0x10,0x66, 0x10,0x03,
0x19,0x03, 0x19,0x03, 0x18,0x03, 0x16,0x03, 0x17,0x02,
0x15,0x03, 0x0F,0x03, 0x0F,0x03, 0x17,0x03, 0x16,0x03,
0x15,0x03, 0x0F,0x66, 0x0F,0x03, 0x0F,0x03, 0x17,0x03,
0x16,0x03, 0x15,0x03, 0x10,0x66, 0x10,0x03, 0x10,0x03,
0x18,0x03, 0x17,0x03, 0x16,0x03, 0x19,0x03, 0x19,0x03,
0x19,0x03, 0x19,0x03, 0x1A,0x03, 0x19,0x03, 0x18,0x03,
0x16,0x03, 0x15,0x66, 0x17,0x03, 0x17,0x03, 0x17,0x02,
0x17,0x03, 0x17,0x03, 0x17,0x02, 0x17,0x03, 0x19,0x03,
0x15,0x03, 0x16,0x03, 0x17,0x01, 0x18,0x03, 0x18,0x03,
0x18,0x67, 0x18,0x04, 0x18,0x03, 0x17,0x03, 0x17,0x03,
0x17,0x04, 0x17,0x04, 0x17,0x03, 0x16,0x03, 0x16,0x03,
0x15,0x03, 0x16,0x03, 0x19,0x66, 0x19,0x03, 0x19,0x03,
0x18,0x03, 0x16,0x03, 0x15,0x02, 0x00,0x00 };
unsigned char code Music_Two[] ={
0x17,0x03, 0x16,0x03, 0x17,0x01, 0x16,0x03, 0x17,0x03,
0x16,0x03, 0x15,0x01, 0x10,0x03, 0x15,0x03, 0x16,0x02,
0x16,0x0D, 0x17,0x03, 0x16,0x03, 0x15,0x03, 0x10,0x03,
0x10,0x0E, 0x15,0x04, 0x0F,0x01, 0x17,0x03, 0x16,0x03,
0x17,0x01, 0x16,0x03, 0x17,0x03, 0x16,0x03, 0x15,0x01,
0x10,0x03, 0x15,0x03, 0x16,0x02, 0x16,0x0D, 0x17,0x03,
0x16,0x03, 0x15,0x03, 0x10,0x03, 0x15,0x03, 0x16,0x01,
0x17,0x03, 0x16,0x03, 0x17,0x01, 0x16,0x03, 0x17,0x03,
0x16,0x03, 0x15,0x01, 0x10,0x03, 0x15,0x03, 0x16,0x02,
0x16,0x0D, 0x17,0x03, 0x16,0x03, 0x15,0x03, 0x10,0x03,
0x10,0x0E, 0x15,0x04, 0x0F,0x01, 0x17,0x03, 0x19,0x03,
0x19,0x01, 0x19,0x03, 0x1A,0x03, 0x19,0x03, 0x17,0x01,
0x16,0x03, 0x16,0x03, 0x16,0x02, 0x16,0x0D, 0x17,0x03,
0x16,0x03, 0x15,0x03, 0x10,0x03, 0x10,0x0D, 0x15,0x00,
0x19,0x03, 0x19,0x03, 0x1A,0x03, 0x1F,0x03, 0x1B,0x03,
0x1B,0x03, 0x1A,0x03, 0x17,0x0D, 0x16,0x03, 0x16,0x03,
0x16,0x0D, 0x17,0x01, 0x17,0x03, 0x17,0x03, 0x19,0x03,
0x1A,0x02, 0x1A,0x02, 0x10,0x03, 0x17,0x0D, 0x16,0x03,
0x16,0x01, 0x17,0x03, 0x19,0x03, 0x19,0x03, 0x17,0x03,
0x19,0x02, 0x1F,0x02, 0x1B,0x03, 0x1A,0x03, 0x1A,0x0E,
0x1B,0x04, 0x17,0x02, 0x1A,0x03, 0x1A,0x03, 0x1A,0x0E,
0x1B,0x04, 0x1A,0x03, 0x19,0x03, 0x17,0x03, 0x16,0x03,
0x17,0x0D, 0x16,0x03, 0x17,0x03, 0x19,0x01, 0x19,0x03,
0x19,0x03, 0x1A,0x03, 0x1F,0x03, 0x1B,0x03, 0x1B,0x03,
0x1A,0x03, 0x17,0x0D, 0x16,0x03, 0x16,0x03, 0x16,0x03,
0x17,0x01, 0x17,0x03, 0x17,0x03, 0x19,0x03, 0x1A,0x02,
0x1A,0x02, 0x10,0x03, 0x17,0x0D, 0x16,0x03, 0x16,0x01,
0x17,0x03, 0x19,0x03, 0x19,0x03, 0x17,0x03, 0x19,0x03,
0x1F,0x02, 0x1B,0x03, 0x1A,0x03, 0x1A,0x0E, 0x1B,0x04,
0x17,0x02, 0x1A,0x03, 0x1A,0x03, 0x1A,0x0E, 0x1B,0x04,
0x17,0x16, 0x1A,0x03, 0x1A,0x03, 0x1A,0x0E, 0x1B,0x04,
0x1A,0x03, 0x19,0x03, 0x17,0x03, 0x16,0x03, 0x0F,0x02,
0x10,0x03, 0x15,0x00, 0x00,0x00 };
unsigned char code Music_Yesterday[]={
0x15,0x03, 0x15,0x03, 0x16,0x03, 0x17,0x02, 0x19,0x02,
0x19,0x03, 0x17,0x03, 0x19,0x03, 0x17,0x03, 0x1A,0x02,
0x19,0x66, 0x17,0x02, 0x17,0x03, 0x19,0x03, 0x1A,0x02,
0x16,0x02, 0x17,0x03, 0x19,0x02, 0x1A,0x15, 0x17,0x03,
0x19,0x03, 0x1A,0x02, 0x21,0x02, 0x20,0x03, 0x1F,0x02,
0x1B,0x03, 0x1B,0x66, 0x19,0x03, 0x17,0x03, 0x19,0x02,
0x17,0x02, 0x16,0x14, 0x15,0x03, 0x15,0x03, 0x16,0x03,
0x17,0x03, 0x19,0x02, 0x19,0x03, 0x19,0x03, 0x17,0x03,
0x19,0x03, 0x17,0x03, 0x1A,0x03, 0x19,0x02, 0x17,0x03,
0x17,0x02, 0x17,0x03, 0x19,0x03, 0x1A,0x02, 0x1B,0x02,
0x17,0x03, 0x19,0x02, 0x1A,0x03, 0x1A,0x01, 0x1B,0x02,
0x20,0x02, 0x1F,0x03, 0x1B,0x03, 0x1A,0x66, 0x1B,0x03,
0x1F,0x03, 0x1B,0x03, 0x1F,0x03, 0x1B,0x02, 0x1A,0x66,
0x1A,0x03, 0x1B,0x03, 0x1F,0x02, 0x1F,0x02, 0x1A,0x03,
0x1F,0x02, 0x20,0x03, 0x20,0x16, 0x1F,0x02, 0x20,0x02,
0x21,0x03, 0x21,0x03, 0x21,0x03, 0x21,0x02, 0x20,0x03,
0x1F,0x03, 0x1B,0x03, 0x1F,0x03, 0x1B,0x03, 0x1A,0x66,
0x17,0x03, 0x19,0x03, 0x19,0x14, 0x1F,0x03, 0x20,0x03,
0x21,0x03, 0x21,0x03, 0x21,0x03, 0x21,0x03, 0x21,0x02,
0x20,0x03, 0x1F,0x03, 0x1F,0x03, 0x1B,0x03, 0x1A,0x66,
0x17,0x03, 0x19,0x03, 0x19,0x14, 0x1A,0x03, 0x1B,0x03,
0x1F,0x03, 0x1B,0x03, 0x1F,0x03, 0x1B,0x03, 0x1F,0x03,
0x20,0x66, 0x1F,0x03, 0x1B,0x03, 0x1F,0x03, 0x1B,0x02,
0x1F,0x03, 0x20,0x66, 0x1F,0x03, 0x20,0x03, 0x21,0x02,
0x21,0x02, 0x20,0x03, 0x1F,0x02, 0x1A,0x03, 0x1A,0x02,
0x17,0x02, 0x17,0x03, 0x1A,0x03, 0x17,0x03, 0x19,0x03,
0x19,0x14, 0x17,0x03, 0x17,0x03, 0x16,0x04, 0x15,0x04,
0x15,0x03, 0x16,0x03, 0x17,0x01, 0x17,0x03, 0x18,0x02,
0x16,0x03, 0x16,0x14, 0x17,0x03, 0x17,0x03, 0x17,0x03,
0x18,0x02, 0x16,0x03, 0x16,0x16, 0x15,0x03, 0x16,0x03,
0x17,0x03, 0x16,0x01, 0x1F,0x02, 0x20,0x02, 0x21,0x03,
0x21,0x03, 0x21,0x03, 0x21,0x02, 0x20,0x03, 0x1F,0x03,
0x1B,0x03, 0x1F,0x03, 0x1B,0x03, 0x1A,0x03, 0x1A,0x02,
0x17,0x03, 0x19,0x03, 0x19,0x14, 0x1F,0x02, 0x20,0x02,
0x21,0x03, 0x21,0x03, 0x21,0x03, 0x21,0x66, 0x20,0x03,
0x1F,0x03, 0x1B,0x03, 0x1F,0x03, 0x1B,0x03, 0x1A,0x66,
0x17,0x03, 0x19,0x03, 0x19,0x00, 0x00,0x00 };
uchar k;
void delay1(void) //延时程序
{
uchar i,j;
for(i=20;i>0;i--)
for(j=248;j>0;j--);
}
void Getch ( )
{ uchar X,Y,Z;
P1=0xff;
P1=0xf3; //先对P0置数行扫描
if(P1!=0xf3) //判断是否有键按下
{ delay1(); //延时,软件去干扰
if(P1!=0xf3) //确认按键按下X = P3;
{
X=P1; //保存行扫描时有键按下时状态
P1=0xfc; //列扫描
Y=P1; //保存列扫描时有键按下时状态
Z=X|Y;
//取出键值
switch ( Z ) //判断键值（那一个键按下）
{
case 0xf9: k=0; break; //对键值赋值
case 0xf5: k=1; break;
case 0xfa: k=2; break;
case 0xf6: k=3; break;
}
}
}
}
void Delay()
{ uint uiCount;
for(uiCount=0;uiCount<250;uiCount++);
}
void WriteCMD(uchar Commond)//LCD写指令函数
{
Delay(); //先延时。
LCDE=1; //然后把ＬＣＤ改为写入命令状态。
LCDRS=0;
LCDRW=0;
LCDPORT=Commond; //再输出命令。
LCDE=0; //最后执行命令。
}
void WriteData(uchar dat)//ＬＣＤ写数据函数
{ Delay(); //先延时。
LCDE=1; //然后把ＬＣＤ改为写入数据状态。
LCDRS=1;
LCDRW=0;
LCDPORT=dat; //再输出数据。
LCDE=0; //最后显示数据。
}
void init()
{
LCDRW=0;
LCDE=0;
WriteCMD(0x38);
WriteCMD(0x0c);
WriteCMD(0x06);
WriteCMD(0x01);
WriteCMD(0x80);
}
void mydelay(int x)
{ int i,j;
for(i=x;i>0;i--)
for(j=255;j>0;j--);
}
void InitialSound(void)
{
BeepIO = 0;
Sound_Temp_TH1 = (65535-(1/1200)*SYSTEM_OSC)/256; // 计算TL1应装入的初值 (10ms的初装值)
Sound_Temp_TL1 = (65535-(1/1200)*SYSTEM_OSC)%256; // 计算TH1应装入的初值
TH1 = Sound_Temp_TH1;
TL1 = Sound_Temp_TL1;
TMOD |= 0x11;
ET0 = 1;
ET1 = 0;
TR0 = 0;
TR1 = 0;
EA = 1;
}
void BeepTimer0(void) interrupt 1 //音符发生中断
{
BeepIO = !BeepIO;
TH0 = Sound_Temp_TH0;
TL0 = Sound_Temp_TL0;
}
void Play(unsigned char *Sound,unsigned char Signature,unsigned Octachord,unsigned int Speed)
{
unsigned int NewFreTab[12]; //新的频率表
unsigned char i,j;
unsigned int Point,LDiv,LDiv0,LDiv1,LDiv2,LDiv4,CurrentFre,Temp_T,SoundLength;
unsigned char Tone,Length,SL,SH,SM,SLen,XG,FD;
for(i=0;i<12;i++) // 根据调号及升降八度来生成新的频率表
{
j = i + Signature;
if(j > 11)
{
j = j-12;
NewFreTab = FreTab[j]*2;
}
else
NewFreTab = FreTab[j];
if(Octachord == 1)
NewFreTab>>=2;
else if(Octachord == 3)
NewFreTab<<=2;
}
SoundLength = 0;
while(Sound[SoundLength] != 0x00) //计算歌曲长度
{
SoundLength+=2;
}
Point = 0;
Tone = Sound[Point];
Length = Sound[Point+1]; // 读出第一个音符和它时时值
LDiv0 = 12000/Speed; // 算出1分音符的长度(几个10ms)
LDiv4 = LDiv0/4; // 算出4分音符的长度
LDiv4 = LDiv4-LDiv4*SOUND_SPACE; // 普通音最长间隔标准
TR0 = 0;
TR1 = 1;
while(Point < SoundLength&&K1==1) //歌曲代码未放完且暂停键未被按下
{
SL=Tone%10; //计算出音符
SM=Tone/10%10; //计算出高低音
SH=Tone/100; //计算出是否升半
CurrentFre = NewFreTab[SignTab[SL-1]+SH]; //查出对应音符的频率
if(SL!=0)
{
if (SM==1) CurrentFre >>= 2; //低音
if (SM==3) CurrentFre <<= 2; //高音
Temp_T = 65536-(50000/CurrentFre)*10/(12000000/SYSTEM_OSC);//计算计数器初值
Sound_Temp_TH0 = Temp_T/256;
Sound_Temp_TL0 = Temp_T%256;
TH0 = Sound_Temp_TH0;
TL0 = Sound_Temp_TL0 + 12; //加12是对中断延时的补偿
}
SLen=LengthTab[Length%10]; //算出是几分音符
XG=Length/10%10; //算出音符类型(0普通1连音2顿音)
FD=Length/100;
LDiv=LDiv0/SLen; //算出连音音符演奏的长度(多少个10ms)
if (FD==1)
LDiv=LDiv+LDiv/2;
if(XG!=1)
if(XG==0) //算出普通音符的演奏长度
if (SLen<=4)
LDiv1=LDiv-LDiv4;
else
LDiv1=LDiv*SOUND_SPACE;
else
LDiv1=LDiv/2; //算出顿音的演奏长度
else
LDiv1=LDiv;
if(SL==0) LDiv1=0;
LDiv2=LDiv-LDiv1; //算出不发音的长度
if (SL!=0)
{
TR0=1;
for(i=LDiv1;i>0;i--) //发规定长度的音
{
while(TF1==0);
TH1 = Sound_Temp_TH1;
TL1 = Sound_Temp_TL1;
TF1=0;
}
}
if(LDiv2!=0)
{
TR0=0; BeepIO=0;
for(i=LDiv2;i>0;i--) //音符间的间隔
{
while(TF1==0);
TH1 = Sound_Temp_TH1;
TL1 = Sound_Temp_TL1;
TF1=0;
}
}
Point+=2;
Tone=Sound[Point];
Length=Sound[Point+1];
}
BeepIO = 0;
}
main()
{ uint i;
k=8;
init();
for(i=0;i<15;i++)
{
WriteData(tab); //LCD写数据函数写第一行
mydelay(50);
}
mydelay(1000);
WriteCMD(0x80+0x40+2); //将指针设到第二行空两字符
for(i=0;i<6;i++)
{
WriteData(tab1);
mydelay(50);
}
InitialSound(); //发音初始化程序
while(1)
{ Getch(); //扫描键盘，获得键值
if(k==0) //若键值为0
{ uint i;
init();
for(i=0;i<10;i++)
{
WriteData(tab2); //写第一首歌序号
mydelay(50);
}
mydelay(1000);
WriteCMD(0x80+0x40); //转到第二行
for(i=0;i<9;i++)
{ WriteData(tab3); //写歌名
mydelay(50);
}
Play(Music_Girl,0,3,360); //播放第一首歌
mydelay(500);
break;
}
else if (k==1) //若键值为1
{ uint i;
init();
for(i=0;i<11;i++)
{ WriteData(tab4); //写第二首歌序号
mydelay(50);
}
mydelay(1000);
WriteCMD(0x80+0x40); //转到第二行
for(i=0;i<11;i++)
{
WriteData(tab5); //写歌名
mydelay(50);
}
Play(Music_Jingle,0,3,360); //播放第二首歌
mydelay(500);
break;
}
else if (k==2) //若键值为2
{ uint i;
init();
for(i=0;i<10;i++)
{ WriteData(tab6); //写第三首歌序号
mydelay(50);
}
mydelay(1000);
//WriteCMD(0x01);
WriteCMD(0x80+0x40); //转到第二行
for(i=0;i<6;i++)
{
WriteData(tab7); //写歌名
mydelay(50);
}
Play(Music_Two,0,3,360); //播放第三首歌
mydelay(500);

1 概述

传统的音乐盒多是机械音乐盒，其工作原理是通过齿轮带动一个带有铁钉的铁桶转动,铁桶上的铁钉撞击铁片制成的琴键，从而发出声音。但是，机械式的音乐盒体积比较大，比较笨重，且发音单调。水、灰尘等外在因素，容易使内部金属发音条变形，从而造成发音跑调。另外，机械音乐盒放音时为了让音色稳定,必须放平不能动摇，而且价格昂贵，不能实现大批量生产。基于单片机设计制作的电子式音乐盒。与传统的机械式音乐盒相比更小巧，音质更优美且能演奏和弦音乐。电子式音乐盒动力来源是电池，制作工艺简单，可进行批量生产，所以价格便宜。基于单片机制作的电子式音乐盒，控制功能强大，可根据需要选歌，使用方便。所放歌曲的节奏可以根据需要进行设置，根据存储容量的大小，可以尽可能多的存储歌曲。另外，可以设计彩灯外观效果，增设放歌时间、序号显示灯功能，使音乐盒的功能更加丰富。

1.1单片机数字音乐盒有关介绍
电子音乐已广泛地应用于社会生活的各个领域。其类型从音乐卡片到CD、MP3 等多种多样，制作原理也各不相同。声音是通过振动产生的。单片机对某一I/O引脚以一定的频率循环置1和清0，这一引脚便产生一定频率的方波，该方波通过放大后作用于扬声器便产生一定频率的声音。若改变输出方波的频率，产生的声音也就改变了。通过控制输出方波的时间长短,声音的长短也就得到控制。因此，根据乐谱，单片机就可产生电子音乐。音乐中最关键的两个要素是音符和节拍。单片机控制的音乐发生器系统由硬件电路和软件两部分构成。利用单片机控制的电子音乐发生器软硬件上具有独特的优点，系统的开发周期短，成本低，电路制作容易。更换歌曲时，硬件电路无需作任何修改，只需修改软件即可实现。软件编程时，可用51系列单片机的汇编语言或C51语言实现。同时还可根据个人的习好通过软件改变节拍的延时时间，增加电子音乐的趣味性。

1.1.1发音原理介绍

发音原理：播放一段音乐需要的是两个元素，一个是音调，另一个是音符。首先要了解对应的音调，音调主要由声音的频率决定，同时也与声音强度有关。对一定强度的纯音，音调随频率的升降而升降；对一定频率的纯音、低频纯音的音调随声强增加而下降，高频纯音的音调却随强度增加而上升。另外，音符的频率有所不同。基于上面的内容，这样就对发音的原理有了一些初步的了解。

音符的发音主要靠不同的音频脉冲。利用单片机的内部定时器/计数器0，使其工作在模式1，定时中断，然后控制P3.7引脚的输出音乐。只要算出某一音频的周期（1/频率），然后将此周期除以2，即为半周期的时间，利用定时器计时这个半周期时间，每当计时到后就将输出脉冲的I/O反相，然后重复计时此半周期时间再对I/O反相，就可在I/O脚上得到此频率的脉冲。

1.1.2 音符频率的产生

音符及定时器初始值：

例如：中音1（do）的音频=523HZ,周期T=1/523s=1912

定时器/计数器0的定时时间为：T/2=1912/2

定时器956的计数值=定时时间/机器周期=956/1=956(时钟频率=12MHZ)

装入T0计数器初值为65536-956=64580
将64580装入T0寄存器中，启动T0工作后，每计数956次时将产生溢出中断，进入中断服务时，每次对P3.0引脚的输出值进行取反，就可得到中音DO（523HZ）的音符音频。将51单片机内部定时器工作在计数器模式1下，改变计数初值TH0,TL0以产生不同的频率。

若该设计使用数字电路完成,所设计的电路相当复杂,大概需要十几片数字集成块,其功能也主要依赖于数字电路的各功能模块的组合来实现,焊接的过程比较复杂,成本也非常高。若用单片机来设计制作完成,由于其功能的实现主要通过软件编程来完成,那么就降低了硬件电路的复杂性,而且其成本也有所降低,所以在该设计中采用单片机利用AT89C51,它是低功耗、高性能的CMOS型8位单片机。片内带有4KB的Flash存储器,且允许在系统内改写或用编程器编程。另外, AT89C51的指令系统和引脚与8051完全兼容,片内有128B 的RAM、32条I/O口线、2个16位定时计数器、5个中断源、一个全双工串行口等.

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