[EK-LM3S8962]TI EK-LM3S8962开发板使用蜂鸣器播放音乐《梁祝》的实现
TI EK-LM3S8962使用蜂鸣器播放音乐《梁祝》的实现
TI的EK-LM3S8962开发板有着比较丰富的外设，由于个人从小对音乐感兴趣，因此利用其中的蜂鸣器外设来实现音乐播放的功能，下面对此进行逐一解析：
先上张开发板的Layout图：
![[EK-LM3S8962]TI EK-LM3S8962开发板使用蜂鸣器播放音乐《梁祝》的实现_第1张图片](http://img.e-com-net.com/image/info5/3fb84650b528428dace56d001a5b7558.jpg)
要实现音乐播放，首先要明白数字音乐是如何播放出来的？
首先需要了解一个事实，那就是我们所听到的
音乐只是一系列不同频率的声音按照一定的节奏播放出来。
但是乐音是有特定的频率的，因此我们首先要定义不同的乐音音节：
#ifndef __MUSIC_H__
#define __MUSIC_H__
// 定义低音音名（数值单位：Hz）
#define L1 262 // c
#define L2 294 // d
#define L3 330 // e
#define L4 349 // f
#define L5 392 // g
#define L6 440 // a1
#define L7 494 // b1
// 定义中音音名
#define M1 523 // c1
#define M2 587 // d1
#define M3 659 // e1
#define M4 698 // f1
#define M5 784 // g1
#define M6 880 // a2
#define M7 988 // b2
// 定义高音音名
#define H1 1047 // c2
#define H2 1175 // d2
#define H3 1319 // e2
#define H4 1397 // f2
#define H5 1568 // g2
#define H6 1760 // a3
#define H7 1976 // b3
// 定义时值单位，决定演奏速度（数值单位：ms）
#define T 3600
// 定义音符结构
typedef struct
{
short mName; // 音名：取值L1～L7、M1～M7、H1～H7分别表示低音、中音、高音的
// 1234567，取值0表示休止符
short mTime; // 时值：取值T、T/2、T/4、T/8、T/16、T/32分别表示全音符、
// 二分音符、四分音符、八分音符…，取值0表示演奏结束
}
tNote;
//
typedef struct _tMusic
{
struct tNote;
char cName[20];
}
tMusic;
//
extern void playNote(const tNote * pNote);
extern void displayNoteName(const tMusic * pMusic);
#endif/*__MUSIC_H__*/
/************************************************************************************
** File: - E:\ARM\lm3s8962projects\uCOS_II\uCOS2.52_Keil_Led_Buz\User\score.h
**
** Copyright (C), tcpipstack, All Rights Reserved!
**
** Description:
** some music scores
**
** Version: 1.0
** Date created: 12:06:54,01/10/2012
** Author: tcpipstack
**
** --------------------------- Revision History: --------------------------------
** <author> <data> <desc>
**
************************************************************************************/
#ifndef __SCORE_H_
#define __SCORE_H_
#include "music.h"
// 定义乐曲：《化蝶》（梁祝）
const tNote ButterflyLove[] =
{
{L3, T/4},
{L5, T/8+T/16},
{L6, T/16},
{M1, T/8+T/16},
{M2, T/16},
{L6, T/16},
{M1, T/16},
{L5, T/8},
{M5, T/8+T/16},
{H1, T/16},
{M6, T/16},
{M5, T/16},
{M3, T/16},
{M5, T/16},
{M2, T/2},
{M2, T/8},
{M2, T/16},
{M3, T/16},
{L7, T/8},
{L6, T/8},
{L5, T/8+T/16},
{L6, T/16},
{M1, T/8},
{M2, T/8},
{L3, T/8},
{M1, T/8},
{L6, T/16},
{L5, T/16},
{L6, T/16},
{M1, T/16},
{L5, T/2},
{M3, T/8+T/16},
{M5, T/16},
{L7, T/8},
{M2, T/8},
{L6, T/16},
{M1, T/16},
{L5, T/8},
{L5, T/4},
{L3, T/16},
{L5, T/16},
{L3, T/8},
{L5, T/16},
{L6, T/16},
{L7, T/16},
{M2, T/16},
{L6, T/4+T/8},
{L5, T/16},
{L6, T/16},
{M1, T/8+T/16},
{M2, T/16},
{M5, T/8},
{M3, T/8},
{M2, T/8},
{M3, T/16},
{M2, T/16},
{M1, T/8},
{L6, T/16},
{L5, T/16},
{L3, T/4},
{M1, T/4},
{L6, T/16},
{M1, T/16},
{L6, T/16},
{L5, T/16},
{L3, T/16},
{L5, T/16},
{L6, T/16},
{M1, T/16},
{L5, T/2},
{0, T/4},
{0, T/4},
{ 0, 0} // 结束
};
// Little Star
const tNote LittleStar[] =
{
{M1, T/4},
{M1, T/4},
{M5, T/4},
{M5, T/4},
{M6, T/4},
{M6, T/4},
{M5, T/2},
{M4, T/4},
{M4, T/4},
{M3, T/4},
{M3, T/4},
{M2, T/4},
{M2, T/4},
{M1, T/2},
{0, 0},
};
// Long Long ago
const tNote LongLongAgo[] =
{
{M1, T/4},
{M1, T/8},
{M2, T/8},
{M3, T/4},
{M3, T/8},
{M4, T/8},
{M5, T/4},
{M6, T/8},
{M5, T/8},
{M3, T/2+T/4},
{M5, T/4},
{M4, T/8},
{M3, T/8},
{M2, T/2+T/4},
{M4, T/4},
{M3, T/8},
{M2, T/8},
{M1, T/2+T/4},
{0, 0},
};
// Long Long ago
const tNote LongLongAgo[] =
{
{M1, T/4},
{M1, T/8},
{M2, T/8},
{M3, T/4},
{M3, T/8},
{M4, T/8},
{M5, T/4},
{M6, T/8},
{M5, T/8},
{M3, T/2+T/4},
{M5, T/4},
{M4, T/8},
{M3, T/8},
{M2, T/2+T/4},
{M4, T/4},
{M3, T/8},
{M2, T/8},
{M1, T/2+T/4},
{0, 0},
};
#endif /* __SCORE_H_ */
定义了音节和歌谱之后，按照如下方法调用：
/************************************************************************************
** Function: playNote()
** Routine Description: -
** 演奏乐曲，在PWM发声的同时点亮LED灯，反之熄灭
** Input parameters: -
** The Note Pointer.
** Output parameters: NONE
** Returned Value: NONE
** Remarks:
**
** Date created: 12:21:20,01/10/2012
** Author: tcpipstack
************************************************************************************/
void playNote(const tNote *pNote)
{
while (1)
{
if (pNote->mTime == 0)
{
break;
}
setPWMFreq(pNote->mName);
setPWMState(TRUE);
ledOn(TARGET_LED_EN);
SysCtlDelay(pNote->mTime * (SysCtlClockGet() / 2000));
setPWMState(FALSE);
ledOff(TARGET_LED_EN);
SysCtlDelay(10 * (SysCtlClockGet() / 2000));
pNote++;
}
SysCtlDelay(2000 * (SysCtlClockGet() / 2000));
}
/************************************************************************************
** Function: displayNoteName()
** Routine Description: -
** display the note name on the screen
** Input parameters: -
** NONE
** Output parameters: NONE
** Returned Value: NONE
** Remarks:
**
** Date created: 12:32:45,01/10/2012
** Author: tcpipstack
************************************************************************************/
void displayNoteName(const tMusic *pMusic)
{
RIT128x96x4StringDraw(pMusic->cName, 0, 10*2+6, 11);
}
最后我们在uC/OS-II里面作为一个music任务，这样播放过程中不会被其他任务所抢占而中断
/************************************************************************************
** Function: taskMusic()
** Routine Description: -
** the Music Task
** Input parameters: -
** NONE
** Output parameters: NONE
** Returned Value: NONE
** Remarks:
**
** Date created: 11:58:59,01/10/2012
** Author: Long.Luo
************************************************************************************/
static void taskMusic(void *parg)
{
(void)parg;
while (1)
{
RIT128x96x4Clear();
RIT128x96x4StringDraw("Task Music", 30, 20, 15);
playNote(ButterflyLove);
OSTimeDly(2 * OS_TICKS_PER_SEC);
}
}
以上