看一个蜂鸣器播放音乐的程序吧,程序里把节拍和音调分别对应,非常有广泛性,
这个夜空中最亮的星的音乐,虽说蜂鸣器没有太大的用处,
非常锻炼定时器的使用和复杂编程;
#include "stc12c5a60s2.h"
sbit PWM=P1^3;
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 - (32000000/12) / (523*2), //中音1
65536 - (32000000/12) / (587*2), //2
65536 - (32000000/12) / (659*2), //3
65536 - (32000000/12) / (698*2), //4
65536 - (32000000/12) / (784*2), //5
65536 - (32000000/12) / (880*2), //6
65536 - (32000000/12) / (988*2), //7
65536 - (32000000/12) / (1047*2), //高音1
65536 - (32000000/12) / (1175*2), //2
65536 - (32000000/12) / (1319*2), //3
65536 - (32000000/12) / (1397*2), //4
65536 - (32000000/12) / (1568*2), //5
65536 - (32000000/12) / (1760*2), //6
65536 - (32000000/12) / (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 T1RH = 0xFF; //T0重载值的高字节
unsigned char T1RL = 0x00; //T0重载值的低字节
void PlayMUSIC();
void main()
{
unsigned int i;
EA=1;
TMOD=0x10;
TH1=0x6f;
TL1=0x11;
ET1=1;
TR1=1;
PWM=0;
while(1)
{
PlayMUSIC(); //播放乐曲
for (i=0; i<40000; i++); //停止一段时间
}
}
void PlayMUSIC()
{
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
//夜空中最亮的星
unsigned char code MUSICNote[] = {
3,3,10, 9,9, 8, 8, 8, 8, 8, 8,8, 6,5, 12, 13, 13, 8,9, 10, 12, 12, 8, 9,
8, 8, 8, 8,8, 6,5, 13,14, 14,14, 8,8, 9, 10, 12, 12,12, 10, 9, 9,
};
//夜空中最亮的星节拍表,4表示一拍,1就是1/4拍,8就是2拍
unsigned char code MUSICBeat[] = {
4, 2,2, 2,2, 4, 2,2, 2,2, 2,2, 2, 2, 4, 4, 4, 2,2, 2, 4, 4, 4, 2,
4, 2,2, 2,2, 2,2, 2,4, 2,2, 2,2, 2, 2 , 4, 2,2, 4, 2, 16,
};
for (beat=0; beat<sizeof(MUSICNote); ) //用节拍索引作为循环变量
{
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 = MUSICNote[beat] - 1;
T1RH = NoteReload[note] >> 8;
T1RL = 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 = (MUSICBeat[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
{
if (time >= beatTime) //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
time = 0;
beat++;
}
else //当前持续时间未达到总时间时,
{
time++; //累加时间计数
if (time == soundTime) //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,
enable = 0; //用以区分连续的两个节拍
}
}
}
}
}
void ZD() interrupt 3
{
TH1 = T1RH; //重新加载重载值
TL1 = T1RL;
tmrflag = 1;
if (enable) //使能时反转蜂鸣器控制电平
PWM = ~PWM;
else //未使能时关闭蜂鸣器
PWM = 1;
}
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