求教，我用单片机PWM播放WAV噪音非常严重啊，求解。我用的F429开发板上的PWM DAC，但是输出播放WAV时，噪音非常大，求解啊！ 程序如下，WAV是22.050KZ的采样，16位的单声道格式，我用单片机PWM 计数长度是1023，没有分频。求解啊。我用原子带的8位PWM也试过，噪音也一样。
TIM14 22.050KZ的中端，运行refresh（）播放数据，TIM1未用。PWM DAC输出是用的原子的TIM9 通道2.

/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "stm32f4xx_hal.h"

/* USER CODE BEGIN Includes */
#include "yh16.h"
#include "ch.h"
/* USER CODE END Includes */

/* Private variables ---------------------------------------------------------*/
DAC_HandleTypeDef hdac;

TIM_HandleTypeDef htim1;
TIM_HandleTypeDef htim9;
TIM_HandleTypeDef htim14;

/* USER CODE BEGIN PV */
/* Private variables ---------------------------------------------------------*/
void TIM_SetTIM9Compare2(uint32_t compare);
void refresh(void);
void pwm_setvalue(uint16_t value,uint32_t chanel);
/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
void Error_Handler(void);
static void MX_GPIO_Init(void);
static void MX_TIM14_Init(void);
static void MX_DAC_Init(void);
static void MX_TIM1_Init(void);
static void MX_TIM9_Init(void);

void HAL_TIM_MspPostInit(TIM_HandleTypeDef *htim);



/* USER CODE BEGIN PFP */
/* Private function prototypes -----------------------------------------------*/
uint32_t num1,num2,num3,num4,ts;
char value;
int vt;
/* USER CODE END PFP */

/* USER CODE BEGIN 0 */
/* USER CODE BEGIN 4 */
/* USER CODE END 4 */
void TIM_SetTIM9Compare2(uint32_t compare)
{
        TIM9->CCR2=compare;
}
void refresh()
{
        uint16_t temp;
        temp=data[num1+1]*256+data[num1];
        TIM_SetTIM9Compare2(temp/64);
//        temp=temp/8;
//        TIM1->CCR1=temp;
//        TIM1->CCR2=temp;
        pwm_setvalue(temp/8,TIM_CHANNEL_1);
        pwm_setvalue(temp/8,TIM_CHANNEL_2);
//       
//        temp=data3[num2+1]*256+data3[num2];
//        //TIM_SetTIM9Compare2(temp/16);
//        pwm_setvalue(temp/8,TIM_CHANNEL_3);
//        pwm_setvalue(temp/8,TIM_CHANNEL_4);
        num1++;
        num2++;
        if(num1>352400)
        {num1=0;}       
        if(num2>2293500)
        {num2=0;}       
}
/*void refresh()
{
        uint8_t temp;
temp=data[num]+128;
        HAL_DAC_SetValue(&hdac,DAC_CHANNEL_1,DAC_ALIGN_12B_R,temp);
                num++;
        if(num>176280)
        {num=0;}
}*/
/* USER CODE END 0 */

int main(void)
{

  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MCU Configuration----------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* Configure the system clock */
  SystemClock_Config();

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_TIM14_Init();
  MX_DAC_Init();
  MX_TIM1_Init();
  MX_TIM9_Init();

  /* USER CODE BEGIN 2 */
HAL_TIM_Base_Start_IT(&htim14);
HAL_DAC_Start(&hdac,DAC_CHANNEL_1);
HAL_TIM_PWM_Start(&htim9,TIM_CHANNEL_2);
HAL_TIM_PWM_Start(&htim1,TIM_CHANNEL_ALL);
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
  /* USER CODE END WHILE */

  /* USER CODE BEGIN 3 */

  }
  /* USER CODE END 3 */

}

/** System Clock Configuration
*/
void SystemClock_Config(void)
{

  RCC_OscInitTypeDef RCC_OscInitStruct;
  RCC_ClkInitTypeDef RCC_ClkInitStruct;

    /**Configure the main internal regulator output voltage
    */
  __HAL_RCC_PWR_CLK_ENABLE();

  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

    /**Initializes the CPU, AHB and APB busses clocks
    */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = 16;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLM = 8;
  RCC_OscInitStruct.PLL.PLLN = 180;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
  RCC_OscInitStruct.PLL.PLLQ = 4;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

    /**Activate the Over-Drive mode
    */
  if (HAL_PWREx_EnableOverDrive() != HAL_OK)
  {
    Error_Handler();
  }

    /**Initializes the CPU, AHB and APB busses clocks
    */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
  {
    Error_Handler();
  }

    /**Configure the Systick interrupt time
    */
  HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);

    /**Configure the Systick
    */
  HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);

  /* SysTick_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
}

/* DAC init function */
static void MX_DAC_Init(void)
{

  DAC_ChannelConfTypeDef sConfig;

    /**DAC Initialization
    */
  hdac.Instance = DAC;
  if (HAL_DAC_Init(&hdac) != HAL_OK)
  {
    Error_Handler();
  }

    /**DAC channel OUT1 config
    */
  sConfig.DAC_Trigger = DAC_TRIGGER_NONE;
  sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;
  if (HAL_DAC_ConfigChannel(&hdac, &sConfig, DAC_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }

}

/* TIM1 init function */
static void MX_TIM1_Init(void)
{

  TIM_MasterConfigTypeDef sMasterConfig;
  TIM_OC_InitTypeDef sConfigOC;
  TIM_BreakDeadTimeConfigTypeDef sBreakDeadTimeConfig;

  htim1.Instance = TIM1;
  htim1.Init.Prescaler = 0;
  htim1.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim1.Init.Period = 8191;
  htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim1.Init.RepetitionCounter = 0;
  if (HAL_TIM_PWM_Init(&htim1) != HAL_OK)
  {
    Error_Handler();
  }

  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim1, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }

  sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = 0;
  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfigOC.OCNPolarity = TIM_OCNPOLARITY_HIGH;
  sConfigOC.OCFastMode = TIM_OCFAST_ENABLE;
  sConfigOC.OCIdleState = TIM_OCIDLESTATE_RESET;
  sConfigOC.OCNIdleState = TIM_OCNIDLESTATE_RESET;
  if (HAL_TIM_PWM_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }

  if (HAL_TIM_PWM_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }

  if (HAL_TIM_PWM_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_3) != HAL_OK)
  {
    Error_Handler();
  }

  if (HAL_TIM_PWM_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_4) != HAL_OK)
  {
    Error_Handler();
  }

  sBreakDeadTimeConfig.OffStateRunMode = TIM_OSSR_DISABLE;
  sBreakDeadTimeConfig.OffStateIDLEMode = TIM_OSSI_DISABLE;
  sBreakDeadTimeConfig.LockLevel = TIM_LOCKLEVEL_OFF;
  sBreakDeadTimeConfig.DeadTime = 0;
  sBreakDeadTimeConfig.BreakState = TIM_BREAK_DISABLE;
  sBreakDeadTimeConfig.BreakPolarity = TIM_BREAKPOLARITY_HIGH;
  sBreakDeadTimeConfig.AutomaticOutput = TIM_AUTOMATICOUTPUT_DISABLE;
  if (HAL_TIMEx_ConfigBreakDeadTime(&htim1, &sBreakDeadTimeConfig) != HAL_OK)
  {
    Error_Handler();
  }

  HAL_TIM_MspPostInit(&htim1);

}

/* TIM9 init function */
static void MX_TIM9_Init(void)
{

  TIM_OC_InitTypeDef sConfigOC;

  htim9.Instance = TIM9;
  htim9.Init.Prescaler = 0;
  htim9.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim9.Init.Period = 1023;
  htim9.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  if (HAL_TIM_PWM_Init(&htim9) != HAL_OK)
  {
    Error_Handler();
  }

  sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = 0;
  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
  if (HAL_TIM_PWM_ConfigChannel(&htim9, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }
  HAL_TIM_MspPostInit(&htim9);
}

/* TIM14 init function */
static void MX_TIM14_Init(void)
{

  htim14.Instance = TIM14;
  htim14.Init.Prescaler = 1020;
  htim14.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim14.Init.Period = 1;
  htim14.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  if (HAL_TIM_Base_Init(&htim14) != HAL_OK)
  {
    Error_Handler();
  }

}

/** Configure pins as
        * Analog
        * Input
        * Output
        * EVENT_OUT
        * EXTI
*/
static void MX_GPIO_Init(void)
{

  GPIO_InitTypeDef GPIO_InitStruct;

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOB_CLK_ENABLE();
  __HAL_RCC_GPIOE_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0|GPIO_PIN_1, GPIO_PIN_RESET);

  /*Configure GPIO pins : PB0 PB1 */
  GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

}

/* USER CODE BEGIN 4 */
/* USER CODE BEGIN 4 */
void pwm_setvalue(uint16_t value,uint32_t channel)
{
    TIM_OC_InitTypeDef sConfigOC;

    sConfigOC.OCMode = TIM_OCMODE_PWM1;
    sConfigOC.Pulse = value;
    sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
    sConfigOC.OCFastMode = TIM_OCFAST_ENABLE;
    HAL_TIM_PWM_ConfigChannel(&htim1, &sConfigOC, channel);
    HAL_TIM_PWM_Start(&htim1, channel);   
}
/* USER CODE END 4 */
/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @param  None
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler */
  /* User can add his own implementation to report the HAL error return state */
  while(1)
  {
  }
  /* USER CODE END Error_Handler */
}

#ifdef USE_FULL_ASSERT

/**
   * @brief Reports the name of the source file and the source line number
   * where the assert_param error has occurred.
   * @param file: pointer to the source file name
   * @param line: assert_param error line source number
   * @retval None
   */
void assert_failed(uint8_t* file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
    ex: printf("Wrong parameters value: file %s on line %d ", file, line) */
  /* USER CODE END 6 */

}

#endif

/**
  * @}
  */

/**
  * @}
*/

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/