#include <reg52.h>
sbit BUZZ = P1^6; //蜂鸣器控制引脚
unsigned int code NoteFrequ[] = { //中音1-7 和高音1-7 对应频率列表
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 对应的定时器重载值
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; //蜂鸣器发声使能标志
bit tmrflag = 0; //定时器中断完成标志
unsigned char T0RH = 0xFF; //T0 重载值的高字节
unsigned char T0RL = 0x00; //T0 重载值的低字节
void PlayTwoTiger();
void main(){
unsigned int i;
EA = 1; //使能全局中断
TMOD = 0x01; //配置 T0 工作在模式1
TH0 = T0RH;
TL0 = T0RL;
ET0 = 1; //使能 T0 中断
TR0 = 1; //启动 T0
while (1){
PlayTwoTiger(); //播放乐曲--两支老虎
for (i=0; i<40000; i++); //停止一段时间
}
}
/* 两支老虎乐曲播放函数 */
void PlayTwoTiger(){
unsigned char beat; //当前节拍索引
unsigned char note; //当前节拍对应的音符
unsigned int time = 0; //当前节拍计时
unsigned int beatTime = 0; //当前节拍总时间
unsigned int soundTime = 0; //当前节拍需发声时间
//两只老虎音符表
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,
};
//两只老虎节拍表，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,
};
//用节拍索引作为循环变量
for (beat=0; beat<sizeof(TwoTigerNote); ){
while (!tmrflag); //每次定时器中断完成后，检测并处理节拍
tmrflag = 0;
if (time == 0){ //当前节拍播完则启动一个新节拍
note = TwoTigerNote[beat] - 1;
T0RH = NoteReload[note] >> 8;
T0RL = NoteReload[note];
//计算节拍总时间，右移2位相当于除4，移位代替除法可以加快执行速度
beatTime = (TwoTigerBeat[beat] * NoteFrequ[note]) >> 2;
//计算发声时间，为总时间的 0.75，移位原理同上
soundTime = beatTime - (beatTime >> 2);
enable = 1; //指示蜂鸣器开始发声
time++;
}else{ //当前节拍未播完则处理当前节拍
//当前持续时间到达节拍总时间时归零，
//并递增节拍索引，以准备启动新节拍
if (time >= beatTime){
time = 0;
beat++;
}else{ //当前持续时间未达到总时间时，
time++; //累加时间计数
//到达发声时间后，指示关闭蜂鸣器，
//插入 0.25*总时间的静音间隔，
if (time == soundTime){
enable = 0; //用以区分连续的两个节拍
}
}
}
}
}
/* T0 中断服务函数，用于控制蜂鸣器发声 */
void InterruptTimer0() interrupt 1{
TH0 = T0RH; //重新加载重载值
TL0 = T0RL;
tmrflag = 1;
if (enable){ //使能时反转蜂鸣器控制电平
BUZZ = ~BUZZ;
}else{ //未使能时关闭蜂鸣器
BUZZ = 1;
}
}
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