STM32F103ZET6利用定时器控制ADC采样并用DMA存储，然后用FFT算法计算低频周期性变化直流信号的频率和幅值，使用HAL库

实现。

以下是实现步骤：

1. 定义ADC采样通道和DMA缓存区。

#define ADC_CHANNEL      ADC_CHANNEL_0
#define ADC_BUFFER_SIZE  256

uint16_t ADC_Buffer[ADC_BUFFER_SIZE];

2. 配置ADC和DMA，使其能够进行采样和存储。

ADC_HandleTypeDef hadc;
DMA_HandleTypeDef hdma_adc;

void MX_ADC_Init(void)
{
  ADC_ChannelConfTypeDef sConfig = {0};

  /** Configure the global features of the ADC (Clock, Resolution, Data Alignment and number of conversion) 
  */
  hadc.Instance = ADC1;
  hadc.Init.ScanConvMode = DISABLE;
  hadc.Init.ContinuousConvMode = ENABLE;
  hadc.Init.DiscontinuousConvMode = DISABLE;
  hadc.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc.Init.DataAlign = ADC_DATAALIGN_RIGHT;
  hadc.Init.NbrOfConversion = 1;
  if (HAL_ADC_Init(&hadc) != HAL_OK)
  {
    Error_Handler();
  }

  /** Configure Regular Channel 
  */
  sConfig.Channel = ADC_CHANNEL;
  sConfig.Rank = 1;
  sConfig.SamplingTime = ADC_SAMPLETIME_13CYCLES_5;
  if (HAL_ADC_ConfigChannel(&hadc, &sConfig) != HAL_OK)
  {
    Error_Handler();
  }

}

void MX_DMA_Init(void) 
{
  /* DMA controller clock enable */
  __HAL_RCC_DMA1_CLK_ENABLE();

  /* DMA interrupt init */
  /* DMA1_Channel1_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMA1_Channel1_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA1_Channel1_IRQn);

  /* DMA1_Channel1 init */
  hdma_adc.Instance = DMA1_Channel1;
  hdma_adc.Init.Direction = DMA_PERIPH_TO_MEMORY;
  hdma_adc.Init.PeriphInc = DMA_PINC_DISABLE;
  hdma_adc.Init.MemInc = DMA_MINC_ENABLE;
  hdma_adc.Init.PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD;
  hdma_adc.Init.MemDataAlignment = DMA_MDATAALIGN_HALFWORD;
  hdma_adc.Init.Mode = DMA_CIRCULAR;
  hdma_adc.Init.Priority = DMA_PRIORITY_HIGH;
  if (HAL_DMA_Init(&hdma_adc) != HAL_OK)
  {
    Error_Handler();
  }

  __HAL_LINKDMA(&hadc, DMA_Handle, hdma_adc);

}

3. 配置定时器，使其能够触发ADC采样。

TIM_HandleTypeDef htim;

void MX_TIM_Init(void)
{
  TIM_ClockConfigTypeDef sClockSourceConfig = {0};
  TIM_MasterConfigTypeDef sMasterConfig = {0};

  htim.Instance = TIM2;
  htim.Init.Prescaler = 72-1; // 1 MHz
  htim.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim.Init.Period = 100-1; // 10 kHz
  htim.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  if (HAL_TIM_Base_Init(&htim) != HAL_OK)
  {
    Error_Handler();
  }
  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sMasterConfig.MasterOutputTrigger = TIM_TRGO_UPDATE;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }

}

4. 在定时器中断中开启ADC采样和DMA传输，并在DMA传输完成中断中进行FFT计算。

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
  if (htim->Instance == TIM2) {
    HAL_ADC_Start_DMA(&hadc, (uint32_t*)ADC_Buffer, ADC_BUFFER_SIZE);
  }
}

void HAL_DMA_IRQHandler(DMA_HandleTypeDef *hdma)
{
  if (hdma->Instance == DMA1_Channel1) {
    if (hdma->State == HAL_DMA_STATE_READY) {
      arm_cfft_radix4_instance_f32 S;
      uint32_t ifftFlag = 0;
      uint32_t doBitReverse = 1;
      float32_t maxValue;
      arm_rfft_fast_f32(&S, (float32_t*)ADC_Buffer, (float32_t*)ADC_Buffer, ifftFlag);
      arm_cmplx_mag_f32((float32_t*)ADC_Buffer, (float32_t*)ADC_Buffer, ADC_BUFFER_SIZE/2);
      arm_max_f32((float32_t*)ADC_Buffer, ADC_BUFFER_SIZE/2, &maxValue, NULL);
      arm_scale_f32((float32_t*)ADC_Buffer, 1.0f/maxValue, (float32_t*)ADC_Buffer, ADC_BUFFER_SIZE/2);
    }
  }
}

5. 在主函数中初始化ADC、DMA和定时器，并启动定时器。

int main(void)
{
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_ADC_Init();
  MX_DMA_Init();
  MX_TIM_Init();
  HAL_TIM_Base_Start_IT(&htim);
  while (1)
  {
  }

}

通过以上步骤，我们可以实现定时器控制ADC采样并用DMA存储，然后用FFT算法计算低频周期性变化直流信号的频率和幅值的功能。