stm32音频降噪程序

STM32音频降噪程序主要是通过数字信号处理的方式，对音频信号进行滤波处理，降低噪声的干扰，提高音频的质量。下面是一个简单的STM32音频降噪程序示例：

1. 初始化ADC和DMA模块，配置ADC的采样率和分辨率，设置DMA传输模式。

2. 在中断服务函数中，将DMA传输的音频数据进行FFT变换，得到音频频谱。

3. 对频谱进行滤波处理，去除高频噪声，并将滤波后的频谱进行IFFT反变换，得到降噪后的音频数据。

4. 将降噪后的音频数据通过DAC输出，完成音频降噪处理。

以下是一个基于STM32F4的音频降噪程序示例，供参考：

#include "stm32f4xx.h"
#include "arm_math.h"

#define FFT_SIZE 1024
#define SAMPLE_RATE 48000
#define BLOCK_SIZE 512

uint16_t micData[BLOCK_SIZE] = {0};
uint16_t outData[BLOCK_SIZE] = {0};

float32_t fftInput[FFT_SIZE] = {0};
float32_t fftOutput[FFT_SIZE] = {0};
float32_t ifftInput[FFT_SIZE] = {0};
float32_t ifftOutput[FFT_SIZE] = {0};
float32_t fftMag[FFT_SIZE/2] = {0};

arm_rfft_fast_instance_f32 fftInstance;
arm_rfft_fast_instance_f32 ifftInstance;

void ADC_Config(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  ADC_InitTypeDef ADC_InitStructure;
  DMA_InitTypeDef DMA_InitStructure;
  
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1,ENABLE);
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2,ENABLE);
  
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
  GPIO_Init(GPIOC, &GPIO_InitStructure);
  
  DMA_InitStructure.DMA_Channel = DMA_Channel_0;
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
  DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)micData;
  DMA_InitStructure.DMA_BufferSize = BLOCK_SIZE;
  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&ADC1->DR;
  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
  DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
  DMA_InitStructure.DMA_Priority = DMA_Priority_High;
  DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
  DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
  DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
  DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
  DMA_Init(DMA2_Stream0, &DMA_InitStructure);
  
  ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
  ADC_InitStructure.ADC_ScanConvMode = DISABLE;
  ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
  ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
  ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC1;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_NbrOfConversion = 1;
  ADC_Init(ADC1, &ADC_InitStructure);
  
  ADC_RegularChannelConfig(ADC1, ADC_Channel_10, 1, ADC_SampleTime_3Cycles);
  
  ADC_DMARequestAfterLastTransferCmd(ADC1, ENABLE);
  ADC_DMACmd(ADC1, ENABLE);
  
  ADC_Cmd(ADC1, ENABLE);
  
  DMA_Cmd(DMA2_Stream0, ENABLE);
}

void DAC_Config(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  DAC_InitTypeDef DAC_InitStructure;
  
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);
  
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
  
  DAC_InitStructure.DAC_Trigger = DAC_Trigger_None;
  DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;
  DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Enable;
  DAC_Init(DAC_Channel_1, &DAC_InitStructure);
  
  DAC_Cmd(DAC_Channel_1, ENABLE);
}

void FFT_Config(void)
{
  arm_rfft_fast_init_f32(&fftInstance, FFT_SIZE);
  arm_rfft_fast_init_f32(&ifftInstance, FFT_SIZE);
}

void FFT_Process(void)
{
  uint16_t i,j;
  
  for(i=0,j=0;i<BLOCK_SIZE;i++)
  {
    fftInput[j++] = micData[i];
    fftInput[j++] = 0;
  }
  
  arm_rfft_fast_f32(&fftInstance, fftInput, fftOutput, 0);
  arm_cmplx_mag_f32(fftOutput, fftMag, FFT_SIZE/2);
  
  for(i=0;i<FFT_SIZE/2;i++)
  {
    if(fftMag[i] > 1000)
    {
      fftOutput[i*2] = 0;
      fftOutput[i*2+1] = 0;
    }
  }
  
  arm_rfft_fast_f32(&ifftInstance, fftOutput, ifftInput, 1);
  
  for(i=0,j=0;i<BLOCK_SIZE;i++)
  {
    outData[i] = ifftOutput[j++];
  }
}

int main(void)
{
  ADC_Config();
  DAC_Config();
  FFT_Config();
  
  while (1)
  {
    FFT_Process();
    DAC_SetChannel1Data(DAC_Align_12b_R, outData[0]);
  }
}

以上代码仅供参考，具体的音频降噪算法和滤波器设计需要根据实际情况进行优化。