#include <reg52.h>
sbit BUZZ = P1^6; //蜂鳴器控制引腳
unsigned int code NoteFrequ[] = { //中音1-7和高音1-7對應頻率列表
523, 587, 659, 698, 784, 880, 988, //中音1-7
1047, 1175, 1319, 1397, 1568, 1760, 1976 //高音1-7
};
unsigned int code NoteReload[] = { //中音1-7和高音1-7對應的定時器重載值
65536 - (11059200/12) / (523*2), //中音1
65536 - (11059200/12) / (587*2), //2
65536 - (11059200/12) / (659*2), //3
65536 - (11059200/12) / (698*2), //4
65536 - (11059200/12) / (784*2), //5
65536 - (11059200/12) / (880*2), //6
65536 - (11059200/12) / (988*2), //7
65536 - (11059200/12) / (1047*2), //高音1
65536 - (11059200/12) / (1175*2), //2
65536 - (11059200/12) / (1319*2), //3
65536 - (11059200/12) / (1397*2), //4
65536 - (11059200/12) / (1568*2), //5
65536 - (11059200/12) / (1760*2), //6
65536 - (11059200/12) / (1976*2), //7
};
bit enable = 1; //蜂鳴器發聲使能標志
bit tmrflag = 0; //定時器中斷完成標志
unsigned char T0RH = 0xFF; //T0重載值的高字節
unsigned char T0RL = 0x00; //T0重載值的低字節
void PlayTwoTiger();
void main()
{
unsigned int i;
EA = 1; //使能全局中斷
TMOD = 0x01; //配置T0工作在模式1
TH0 = T0RH;
TL0 = T0RL;
ET0 = 1; //使能T0中斷
TR0 = 1; //啟動T0
while (1)
{
PlayTwoTiger(); //播放樂曲--兩支老虎
for (i=0; i<40000; i++); //停止一段時間
}
}
/* 兩只老虎樂曲播放函數 */
void PlayTwoTiger()
{
unsigned char beat; //當前節拍索引
unsigned char note; //當前節拍對應的音符
unsigned int time = 0; //當前節拍計時
unsigned int beatTime = 0; //當前節拍總時間
unsigned int soundTime = 0; //當前節拍需發聲時間
//兩只老虎音符表
unsigned char code TwoTigerNote[] = {
1, 2, 3, 1, 1, 2, 3, 1, 3, 4, 5, 3, 4, 5,
5,6, 5,4, 3, 1, 5,6, 5,4, 3, 1, 1, 5, 1, 1, 5, 1,
};
//兩只老虎節拍表，4表示一拍，1就是1/4拍，8就是2拍
unsigned char code TwoTigerBeat[] = {
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 8, 4, 4, 8,
3,1, 3,1, 4, 4, 3,1, 3,1, 4, 4, 4, 4, 8, 4, 4, 8,
};
for (beat=0; beat<sizeof(TwoTigerNote); ) //用節拍索引作為循環變量
{
while (!tmrflag); //每次定時器中斷完成后，檢測并處理節拍
tmrflag = 0;
if (time == 0) //當前節拍播完則啟動一個新節拍
{
note = TwoTigerNote[beat] - 1;
T0RH = NoteReload[note] >> 8;
T0RL = NoteReload[note];
//計算節拍總時間，右移2位相當于除4，移位代替除法可以加快執行速度
beatTime = (TwoTigerBeat[beat] * NoteFrequ[note]) >> 2;
//計算發聲時間，為總時間的0.75，移位原理同上
soundTime = beatTime - (beatTime >> 2);
enable = 1; //指示蜂鳴器開始發聲
time++;
}
else //當前節拍未播完則處理當前節拍
{
if (time >= beatTime) //當前持續時間到達節拍總時間時歸零，
{ //并遞增節拍索引，以準備啟動新節拍
time = 0;
beat++;
}
else //當前持續時間未達到總時間時，
{
time++; //累加時間計數
if (time == soundTime) //到達發聲時間后，指示關閉蜂鳴器，
{ //插入0.25*總時間的靜音間隔，
enable = 0; //用以區分連續的兩個節拍
}
}
}
}
}
/* T0中斷服務函數，用于控制蜂鳴器發聲 */
void InterruptTimer0() interrupt 1
{
TH0 = T0RH; //重新加載重載值
TL0 = T0RL;
tmrflag = 1;
if (enable) //使能時反轉蜂鳴器控制電平
BUZZ = ~BUZZ;
else //未使能時關閉蜂鳴器
BUZZ = 1;
}
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