STM32 USB AUDIO 基础篇①——通过STM32CubeMX生成USB Speaker音频播放Demo（史上最简单）

怼烎@ 2022-09-04 06:50 697阅读 0赞

### 文章目录 ###

*  一、硬件原理
 *  二、STM32CubeMX配置
 *   *  2.1 RCC
     *  2.2 SYS
     *  2.3 I2C1
     *  2.4 USART1
     *  2.5 USB\_OTG\_FS
     *  2.6 I2S2
     *  2.7 USB\_DEVICE
     *  2.8 Clock Configuration
     *  2.9 Project Manager
     *  2.10 生成代码
 *  三、代码完善
 *   *  3.1 WM8978
     *  3.2 usbd\_audio\_if
 *  四、程序流程图
 *   *  4.1 初始化流程
     *  4.2 播放流程

# 一、硬件原理 #

基于正点原子STM32F407探索者开发板，其中音频部分硬件原理图如下

其中WM8978是一款全功能音频处理器，STM32通过控制WM8978即可实现扬声器/喇叭的音频播放，麦克风的音频录制等功能。

主要控制两个接口

*  IIC控制接口，实现WM8978寄存器的读写
 *  I2S数字音频接口，实现音频数据传输（接收和发送）  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70]

# 二、STM32CubeMX配置 #

## 2.1 RCC ##

开发板外接了两个晶振

*  8MHz的高速晶振
 *  32.768kHz的低速晶振

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 1]

## 2.2 SYS ##

`Debug Serial Wire`  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 2]

## 2.3 I2C1 ##

*  GPIO口是PB8/PB9  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 3]  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 4]

## 2.4 USART1 ##

*  用来打印调试日志，波特率调到1000000，加快日志打印
 *  Data Direction: Transmit Only
 *  DMA Settings: USART1\_TX
 *  PA9 / PA10  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 5]  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 6]

## 2.5 USB\_OTG\_FS ##

*  Mode:Device Only
 *  global interrupt 勾选  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 7]

## 2.6 I2S2 ##

*  mode: Full-Duplex Master
 *  Audio Frequency: 48KHz
 *  DMA Setting: SPI2\_TX / I2S2\_EXT\_RX
 *  GPIO Setting  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 8]![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 9]  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 10]

## 2.7 USB\_DEVICE ##

*  Class For FS IP: Audio Device Class
 *  USBD\_AUDIO\_FREQ: 48000 sample/s
 *  描述符有些部分可以自定义  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 11]  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 12]

## 2.8 Clock Configuration ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 13]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 14]

## 2.9 Project Manager ##

*  堆栈调大0x4000  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 15]

## 2.10 生成代码 ##

*  右上角 `GENERATE CODE`

# 三、代码完善 #

![在这里插入图片描述][84656060f2c447898c98df7142901284.png]

## 3.1 WM8978 ##

`main.c`

*  `main函数`增加`WM8978_Init();`

int main(void)
    { 
      HAL_Init();
      SystemClock_Config();
      MX_GPIO_Init();
      MX_DMA_Init();
      MX_I2C1_Init();
      MX_I2S2_Init();
      MX_USART1_UART_Init();
      MX_USB_DEVICE_Init();
      WM8978_Init();
      while (1)
      { 
      }
    }

`wm8978.c`

#define DEVICE_ADDRESS 0x1A
    #define WIRTE_ADDRESS (DEVICE_ADDRESS << 1 | 0)
    
    extern I2C_HandleTypeDef hi2c1;
    
    uint8_t WM8978_Write(uint8_t reg_addr, uint16_t data)
    { 
    	uint8_t pData[10] =	{  0 };
    
    	pData[0] = (reg_addr << 1) | ((data >> 8) & 0x01);
    	pData[1] = data & 0xFF;
    	return HAL_I2C_Master_Transmit(&hi2c1, WIRTE_ADDRESS, pData, 2, 1000);
    }
    
    uint32_t WM8978_Init(void)
    { 
    	WM8978_Reset();
    	WM8978_Write(1, 0x0F);	// 模拟放大器使能， 使能输出输入缓存区
    	WM8978_Write(3, 0x7F);	// 使能左右声道和L\ROUT2
    	WM8978_Write(4, 0x10);	// I2S 16bit
    	WM8978_Write(6, 0x00);	// MCU提供时钟
    	WM8978_Write(10, 0x08);	// 输出音质最好
    	WM8978_Write(43, 0x10);	// ROUT2反相
    	WM8978_VolumeCtl(0x3F);
    	return 0;
    }
    
    uint32_t WM8978_Reset(void)
    { 
    	if(WM8978_Write(0, 0)!= HAL_OK)// 软复位
    		return 1;
    	HAL_Delay(10);
    	return 0;
    }

## 3.2 usbd\_audio\_if ##

*  `AUDIO_AudioCmd_FS`中对应`AUDIO_CMD_START`、`AUDIO_CMD_PLAY`和`AUDIO_CMD_STOP`的操作
 *  `HAL_I2S_TxCpltCallback`对应传输完成的USB同步操作

extern I2S_HandleTypeDef hi2s2;
    /** * @brief Handles AUDIO command. * @param pbuf: Pointer to buffer of data to be sent * @param size: Number of data to be sent (in bytes) * @param cmd: Command opcode * @retval USBD_OK if all operations are OK else USBD_FAIL */
    static int8_t AUDIO_AudioCmd_FS(uint8_t* pbuf, uint32_t size, uint8_t cmd)
    { 
      switch(cmd)
      { 
        case AUDIO_CMD_START:
    		HAL_I2S_Transmit_DMA(&hi2s2, (uint16_t*)pbuf, size);
        break;
    
        case AUDIO_CMD_PLAY:
    		HAL_I2S_Transmit_DMA(&hi2s2, (uint16_t*)pbuf, size);
        break;	
    
        case AUDIO_CMD_STOP:
        	HAL_I2S_DMAStop(&hi2s2);
        break;	
      }
      return (USBD_OK);
    }
    
    void HAL_I2S_TxHalfCpltCallback(I2S_HandleTypeDef *hi2s)
    { 
    	HalfTransfer_CallBack_FS();
    }
    
    void HAL_I2S_TxCpltCallback(I2S_HandleTypeDef *hi2s)
    { 
    	TransferComplete_CallBack_FS();
    }

# 四、程序流程图 #

## 4.1 初始化流程 ##

mainhal库stm32f4xx\_hal\_mapwx8978usb\_deviceSTM32\_USB\_DEVICE\_LibraryHAL\_Init()SystemClock\_Config()HAL\_Delay(100)MX\_GPIO\_Init()MX\_DMA\_Init()MX\_I2C1\_Init()HAL\_I2C\_Init()HAL\_I2C\_MspInit()MX\_I2S2\_Init()HAL\_I2S\_Init()HAL\_I2S\_MspInit()WM8978\_Init()MX\_USB\_DEVICE\_Init()USBD\_Init(&hUsbDeviceFS, &FS\_Desc, DEVICE\_FS)USBD\_RegisterClass(&hUsbDeviceFS, &USBD\_AUDIO)USBD\_AUDIO\_RegisterInterface(&hUsbDeviceFS, &USBD\_AUDIO\_fops\_FS)USBD\_Start(&hUsbDeviceFS)HAL\_Delay(100)while(1)mainhal库stm32f4xx\_hal\_mapwx8978usb\_deviceSTM32\_USB\_DEVICE\_Library

## 4.2 播放流程 ##

STM32\_USB\_DEVICE\_Libraryusbd\_audio\_ifhal库AudioCmd(uint8\_t \*pbuf, uint32\_t size, uint8\_t cmd)HAL\_I2S\_Transmit\_DMASTM32\_USB\_DEVICE\_Libraryusbd\_audio\_ifhal库

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