（番外13）GD32L233评测-来点音乐
本帖最后由 韵湖葱白 于 2022-3-10 11:57 编辑## 前言
开工第二天，花半个小时搞定pwm驱动无源蜂鸣器播放音乐。
## 无源蜂鸣器
；所谓无源，是指蜂鸣器内部不带震荡源，需要频率信号驱动。
有源蜂鸣器 | 无源蜂鸣器
---|---
有震荡源-频率固定 | 无震荡源-频率可控
管脚有方向 | 管脚无方向
单向有内阻，一般超过1KΩ | 双向有内阻，一般几百Ω
有电路板 | 无电路板
通电即发声 | 频率信号驱动
贵 | 便宜
由于无源蜂鸣器由频率信号控制，我们可以通过调整控制频率的方式来播放音乐。
人耳能够感受到的声音频率范围为20HZ ~ 20KHZ，音乐的频率一般是几百HZ，不超过2KHZ。
假设我们的定时器频率是100MHZ，我们需要通过分频的方式把PWM的频率降到音乐的频率范围之内：把prescaler值设置为999，频率降为100KHZ，通过调整period使输出频率在声音的范围内。
例如，C调音阶1的频率是262HZ，那么period值就是：100K/262≈382
我们把接口进行封装（代码GD32）：
```
void timer3_freq_change(uint32_t freq_base, uint16_t freq)
{
uint16_t period = freq_base / freq;
timer_autoreload_value_config(TIMER2, period);
timer_event_software_generate(TIMER2, TIMER_EVENT_SRC_UPG);
}
```
其中，freq_base是prescaler之后的值，freq是声音的频率值，我们把这个接口再封装一把。
```
#define TIMER_FREQ_BASE 100000// 100K
#define TIMER_PRESCALER 639 // 分频系数 * 100K = 64M
#define PLAY_SOUND(note)timer3_freq_change(TIMER_FREQ_BASE, note)
```
到这里，播放声音的接口就搞定了。
## 一点乐理
上面我们已经搞定了播放声音的方式，那么在乐理中，我们还需要知道音乐的调子和节拍。
看一段简谱。
简谱的左上角一般标示了这首歌的调子，节拍数和BPM。
《祝你生日快乐》是C调，3/4表示4分音符为1拍，每小节3拍，小蝌蚪=100表示每分钟100拍。
有了这几个数据，我们就可以算出来每拍音符的时长=60s/100=600ms。
关于简谱中的记法：
音符的下点表示低音，上点表示高音，-表示延长音，一个下划线表示时长减半，N个下划线表示时长缩小2^N倍。
()表示间奏或者过门，‖::‖表示重复，上括号表示连音。
如上划横线部分，表示：
前一节：7播放600ms，-表示7继续播放600ms，5下划线播放300ms，5下划线播放300ms，共播放1800ms。
后一节：6播放600ms，5播放600ms，2上加点播放600ms，共播放1800ms。
## 代码部分
### 音符
我们把音符的频率用数组枚举出来备用：
```
const uint16_t freq_A[] = {
0,
221,248,278,294,330,371,416, ///< 低音1-7
441,495,556,589,661,742,833, ///< 普通音1-7
882,990, 1112, 1178, 1322, 1484, 1665 ///< 高音1-7
};
const uint16_t freq_B[] = {
0,
248,278,294,330,371,416,467, ///< 低音1-7
495,556,589,661,742,833,935, ///< 普通音1-7
990, 1112, 1178, 1322, 1484, 1665, 1869 ///< 高音1-7
};
const uint16_t freq_C[] = {
0,
131,147,165,175,196,221,248, ///< 低音1-7
262,294,330,350,393,441,495, ///< 普通音1-7
525,589,661,700,786,882,990 ///< 高音1-7
};
const uint16_t freq_D[] = {
0,
147,165,175,196,221,248,278, ///< 低音1-7
294,330,350,393,441,495,556, ///< 普通音1-7
589,661,700,786,882,990, 1112 ///< 高音1-7
};
const uint16_t freq_E[] = {
0,
165,175,196,221,248,278,312, ///< 低音1-7
330,350,393,441,495,556,624, ///< 普通音1-7
661,700,786,882,990, 1112, 1248 ///< 高音1-7
};
const uint16_t freq_F[] = {
0,
175,196,221,234,262,294,330, ///< 低音1-7
350,393,441,495,556,624,661, ///< 普通音1-7
700,786,882,935, 1049, 1178, 1322 ///< 高音1-7
};
const uint16_t freq_G[] = {
0,
196,221,234,262,294,330,371, ///< 低音1-7
393,441,495,556,624,661,742, ///< 普通音1-7
786,882,935, 1049, 1178, 1322, 1484 ///< 高音1-7
};
```
这里用一个数组把它们组织起来方便调用：
```
const uint16_t *FREQS[] = {freq_A, freq_B, freq_C, freq_E, freq_F, freq_G};
```
同时对外开放一个枚举量方便外部调用（外部只需要知道调号就可以用，并不需要关心具体的频率值）：
```
typedef enum
{
TONE_A,
TONE_B,
TONE_C,
TONE_D,
TONE_E,
TONE_F,
TONE_G,
}tone_e;
```
## 制谱
从上面的推断来看，实际上单个音符的播放时间只跟bpm有关系，在编程上我们需要关心的只有一个点：
**如何表示不同播放时长的音符？**
这里，我们需要用点数学或者编程的技巧。
我们用有规律的数字来表示不同的播放时长，用一个表来说明一下：
音符 | 数学表示方法
---|---
0（空） | 0
低音1-7 | 1-7
普通1-7 | 8-14
高音1-7 | 15-21
---|---
低音1-7(1个下划线) | 31-37
普通1-7(1个下划线) | 38-44
高音1-7(1个下划线) | 45-51
---|---
低音1-7(2个下划线) | 61-67
普通1-7(2个下划线) | 68-74
高音1-7(2个下划线) | 75-81
---|---
低音1-7(3个下划线) | 91-97
普通1-7(3个下划线) | 98-104
高音1-7(3个下划线) | 105-111
---|---
低音1-7(4个下划线) | 121-127
普通1-7(4个下划线) | 128-134
高音1-7(4个下划线) | 135-141
这里用到了线性的表示方法，我们在写程序的时候，就可以很愉快的用if else搞定了。
```
void play_music(uint16_t bpm, tone_e tone, uint16_t *data, uint16_t len)
{
uint16_t delay = 60000/bpm;
uint8_t index;
const uint16_t *freq = FREQS;
for (index = 0; index < len; index++)
{
if (data <= HIGH7)
{
/* 基本音阶 */
PLAY_SOUND(freq]);
delay_ms(delay);
}
else if (data <= HIGH7_)
{
/* 1个_ */
PLAY_SOUND(freq-30]);
delay_ms(delay/2);
}
else if (data <= HIGH7_2)
{
/* 2个_ */
PLAY_SOUND(freq-60]);
delay_ms(delay/4);
}
else if (data <= HIGH7_3)
{
/* 3个_ */
PLAY_SOUND(freq-90]);
delay_ms(delay/8);
}
else if (data <= HIGH7_4)
{
/* 4个_ */
PLAY_SOUND(freq-120]);
delay_ms(delay/16);
}
}
}
```
在上面的程序中，我们再次用到了编程技巧，用简单的宏定义替换数字，方便我们制谱。
```
0 = BASE0
1低音 = LOW1
1 = BASE1
1高音 = HIGH1
1一个下划线 = BASE1_
1两个下划线 = BASE1_2
1三个下划线 = BASE1_3
1四个下划线 = BASE1_4
```
有了这个关系，我们就可以很轻松的制谱了。
例如《祝你生日快乐》中的划横线部分，表示出来就是：
` BASE7, BASE7, BASE5_, BASE5_ `
` BASE6, BASE5, HIGH2 `
到这里，我们就可以很轻松的翻译一首歌了。
我们把宏定义也贴一把：
```
#define BASE0 0
#define LOW1 1
#define LOW2 2
#define LOW3 3
#define LOW4 4
#define LOW5 5
#define LOW6 6
#define LOW7 7
#define BASE1 8
#define BASE2 9
#define BASE3 10
#define BASE4 11
#define BASE5 12
#define BASE6 13
#define BASE7 14
#define HIGH1 15
#define HIGH2 16
#define HIGH3 17
#define HIGH4 18
#define HIGH5 19
#define HIGH6 20
#define HIGH7 21
#define LOW1_ (30+LOW1)
#define LOW2_ (30+LOW2)
#define LOW3_ (30+LOW3)
#define LOW4_ (30+LOW4)
#define LOW5_ (30+LOW5)
#define LOW6_ (30+LOW6)
#define LOW7_ (30+LOW7)
#define BASE1_ (30+BASE1)
#define BASE2_ (30+BASE2)
#define BASE3_ (30+BASE3)
#define BASE4_ (30+BASE4)
#define BASE5_ (30+BASE5)
#define BASE6_ (30+BASE6)
#define BASE7_ (30+BASE7)
#define HIGH1_ (30+HIGH1)
#define HIGH2_ (30+HIGH2)
#define HIGH3_ (30+HIGH3)
#define HIGH4_ (30+HIGH4)
#define HIGH5_ (30+HIGH5)
#define HIGH6_ (30+HIGH6)
#define HIGH7_ (30+HIGH7)
#define LOW1_2 (60+LOW1)
#define LOW2_2 (60+LOW2)
#define LOW3_2 (60+LOW3)
#define LOW4_2 (60+LOW4)
#define LOW5_2 (60+LOW5)
#define LOW6_2 (60+LOW6)
#define LOW7_2 (60+LOW7)
#define BASE1_2 (60+BASE1)
#define BASE2_2 (60+BASE2)
#define BASE3_2 (60+BASE3)
#define BASE4_2 (60+BASE4)
#define BASE5_2 (60+BASE5)
#define BASE6_2 (60+BASE6)
#define BASE7_2 (60+BASE7)
#define HIGH1_2 (60+HIGH1)
#define HIGH2_2 (60+HIGH2)
#define HIGH3_2 (60+HIGH3)
#define HIGH4_2 (60+HIGH4)
#define HIGH5_2 (60+HIGH5)
#define HIGH6_2 (60+HIGH6)
#define HIGH7_2 (60+HIGH7)
#define LOW1_3 (90+LOW1)
#define LOW2_3 (90+LOW2)
#define LOW3_3 (90+LOW3)
#define LOW4_3 (90+LOW4)
#define LOW5_3 (90+LOW5)
#define LOW6_3 (90+LOW6)
#define LOW7_3 (90+LOW7)
#define BASE1_3 (90+BASE1)
#define BASE2_3 (90+BASE2)
#define BASE3_3 (90+BASE3)
#define BASE4_3 (90+BASE4)
#define BASE5_3 (90+BASE5)
#define BASE6_3 (90+BASE6)
#define BASE7_3 (90+BASE7)
#define HIGH1_3 (90+HIGH1)
#define HIGH2_3 (90+HIGH2)
#define HIGH3_3 (90+HIGH3)
#define HIGH4_3 (90+HIGH4)
#define HIGH5_3 (90+HIGH5)
#define HIGH6_3 (90+HIGH6)
#define HIGH7_3 (90+HIGH7)
#define LOW1_4 (120+LOW1)
#define LOW2_4 (120+LOW2)
#define LOW3_4 (120+LOW3)
#define LOW4_4 (120+LOW4)
#define LOW5_4 (120+LOW5)
#define LOW6_4 (120+LOW6)
#define LOW7_4 (120+LOW7)
#define BASE1_4 (120+BASE1)
#define BASE2_4 (120+BASE2)
#define BASE3_4 (120+BASE3)
#define BASE4_4 (120+BASE4)
#define BASE5_4 (120+BASE5)
#define BASE6_4 (120+BASE6)
#define BASE7_4 (120+BASE7)
#define HIGH1_4 (120+HIGH1)
#define HIGH2_4 (120+HIGH2)
#define HIGH3_4 (120+HIGH3)
#define HIGH4_4 (120+HIGH4)
#define HIGH5_4 (120+HIGH5)
#define HIGH6_4 (120+HIGH6)
#define HIGH7_4 (120+HIGH7)
```
## SHOW TIME
### 祝你生日快乐
```
void play_sheng_ri_kuai_le(void)
{
uint16_t bpm = 100;
tone_e tone = TONE_C;
uint16_t gc[] = {
/* 间奏 */
BASE5, BASE5,
HIGH5, HIGH3, HIGH1,
BASE7, BASE6, BASE6,
BASE0, HIGH4_, HIGH4_,
HIGH3, HIGH1, HIGH2,
HIGH1, HIGH1,
/* 第一段 */
BASE5_, BASE5_, // - 祝你
BASE6, BASE5, HIGH1,
BASE7, BASE7, BASE5_, BASE5_, // 乐，祝你
BASE6, BASE5, HIGH2,
HIGH1, HIGH1, BASE5_, BASE5_, // - 祝你
HIGH5, HIGH3, HIGH1,
BASE7, BASE6, BASE6,
BASE0, HIGH4_, HIGH4_, // - 祝你
HIGH3, HIGH1, HIGH2,
HIGH1, HIGH1,
/* 第二段 */
BASE5_, BASE5_, // - 祝你
BASE6, BASE5, HIGH1,
BASE7, BASE7, BASE5_, BASE5_, // 乐，祝你
BASE6, BASE5, HIGH2,
HIGH1, HIGH1, BASE5_, BASE5_, // - 祝你
HIGH5, HIGH3, HIGH1,
BASE7, BASE6, BASE6,
BASE0, HIGH4_, HIGH4_, // - 祝你
HIGH3, HIGH1, HIGH2,
HIGH1, HIGH1,
/* 结束 */
BASE5_, BASE5_, // - 祝你
HIGH5, HIGH3, HIGH1,
BASE7, BASE6, BASE6,
BASE0, HIGH4_, HIGH4_, // - 祝你
HIGH3, HIGH1, HIGH2,
HIGH1, HIGH1, HIGH1
};
play_music(bpm, tone, gc, ARRAY_NUM(gc));
}
```
### 沧海一声笑
```
void play_cang_hai_yi_sheng_xiao(void)
{
uint16_t bpm = 66;
tone_e tone = TONE_A;
uint16_t gz0[] = {
/* 间奏 */
BASE5_2, BASE6_2, HIGH1_2, HIGH2_2, HIGH5_, HIGH2_,
BASE5_2, BASE6_2, HIGH1_2, HIGH2_2, HIGH5_, HIGH2_
};
uint16_t gc123[] = {
/* 第一 二 三段 沧海笑 苍天笑 江山笑 */
BASE6_, BASE6_2, BASE5_2, BASE3_, BASE2_2, BASE1, BASE1,
BASE3_, BASE2_2, BASE1_, LOW6_2, LOW5_2, LOW5, LOW5,
LOW5_, LOW6_2, LOW5_, LOW6_2, LOW1_, LOW2_2, BASE3_, BASE5_,
LOW6_, LOW5_2, BASE3_2, BASE2_2, BASE1_, BASE2
};
uint16_t gc45[] = {
/* 第四段 清风笑 苍生笑 */
BASE6_, BASE6_2, BASE5_2, BASE3_, BASE2_2, BASE1, BASE1,
BASE3_, BASE2_2, BASE1_, LOW6_2, LOW5_2, LOW5, LOW5,
LOW5_, LOW6_2, LOW5_, LOW6_2, LOW1_, LOW2_2, BASE3_, BASE5_,
LOW6_, LOW5_2, BASE3_2, BASE2_2, BASE1_, BASE1, BASE1,
};
uint16_t gz1[] = {
/* 间奏 */
LOW6_2, BASE1_2, BASE2_2, BASE3_2,
LOW6_2, BASE1_2, BASE2_2, BASE3_2,
LOW6_2, BASE1_2, BASE2_2, BASE3_2,
LOW6_2, BASE1_2, BASE2_2, BASE3_2,
LOW6_2, BASE1_2, BASE2_2, BASE3_2,
LOW6_2, BASE1_2, BASE2_2, BASE3_2,
LOW6_2, BASE1_2, BASE2_2, BASE3_2,
LOW6_2, BASE1_2, BASE2_2, BASE3_2,
BASE6_, BASE6_2, BASE5_2, BASE3_, BASE2_, BASE1, BASE1,
BASE3_2, BASE5_2, BASE3_2, BASE2_2, BASE1_, LOW6_, LOW5, LOW5,
LOW5_, LOW6_2, LOW5_, LOW6_2, LOW1_, LOW2_2, BASE3_, BASE5_2,
BASE6_, BASE5_2, BASE5_2, BASE5_2, BASE3_2, BASE2_2, BASE1_2, BASE2, BASE2
};
uint16_t last[] = {
/* 结束 */
BASE6_, BASE6_2, BASE5_2, BASE3_, BASE2_2, BASE1, BASE1,
BASE3_, BASE2_2, BASE1_, LOW6_2, LOW5, LOW5,
LOW5_, LOW6_2, LOW5_, LOW6_2, BASE1_, BASE2_2, BASE3_, BASE5_2,
BASE6_, BASE5_2, BASE5_2, BASE5_2, BASE3_2, BASE2_2, BASE1_2, BASE2, BASE2
};
play_music(bpm, tone, gz0, ARRAY_NUM(gz0));
play_music(bpm, tone, gc123, ARRAY_NUM(gc123));
play_music(bpm, tone, gc123, ARRAY_NUM(gc123));
play_music(bpm, tone, gc123, ARRAY_NUM(gc123));
play_music(bpm, tone, gc45, ARRAY_NUM(gc45));
play_music(bpm, tone, gz1, ARRAY_NUM(gz1));
play_music(bpm, tone, gc45, ARRAY_NUM(gc45));
play_music(bpm, tone, last, ARRAY_NUM(last));
play_music(bpm, tone, last, ARRAY_NUM(last));
}
```
## 视频
<iframe src="//player.bilibili.com/player.html?aid=852074524&bvid=BV1HL4y1u74o&cid=544431311&page=1" scrolling="no" border="0" frameborder="no" framespacing="0" allowfullscreen="true" Height=360 Width=640> </iframe>
<iframe src="//player.bilibili.com/player.html?aid=467061816&bvid=BV1mL411N7ny&cid=544428882&page=1" scrolling="no" border="0" frameborder="no" framespacing="0" allowfullscreen="true"Height=360 Width=640> </iframe>
<p>沧海一声笑</p>
<p> </p>
<p><iframe allowfullscreen="true" frameborder="0" height="450" src="//player.bilibili.com/player.html?bvid=1mL411N7ny&page=1" style="background:#eee;margin-bottom:10px;" width="700"></iframe><br />
</p>
<p>祝你生日快乐</p>
<p> </p>
<p><iframe allowfullscreen="true" frameborder="0" height="450" src="//player.bilibili.com/player.html?bvid=1HL4y1u74o&page=1" style="background:#eee;margin-bottom:10px;" width="700"></iframe><br />
</p>
<p>一看对音频就非常了解，当时上课的时候就搞过这个。</p>
<p>我也把《祝你生日快乐》搞出来了，还没来得及发帖子，就看到你这篇了。<img height="48" src="https://bbs.eeworld.com.cn/static/editor/plugins/hkemoji/sticker/facebook/handshake.gif" width="48" /></p>
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