写一个STM32 C语言通过ADC采样计算THD的重新

下面是一个使用 STM32 的 C 语言编写的通过 ADC 采样计算 THD 的示例代码：

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

#define ADC1_DR_ADDRESS ((uint32_t)0x4001204C)

void ADC1_Init(void);
void TIM2_Init(void);
void GPIO_Init(void);
void NVIC_Configuration(void);
void Delay(__IO uint32_t nCount);
void CalculateTHD(void);

__IO uint16_t ADC1ConvertedValue[1024];
uint32_t SampleCount = 1024;
uint32_t THD = 0;
float32_t harmonic[51];
float32_t signal[1024];

int main(void)
{
  ADC1_Init();
  TIM2_Init();
  GPIO_Init();
  NVIC_Configuration();

  while (1)
  {
    CalculateTHD();
  }
}

void ADC1_Init(void)
{
  ADC_InitTypeDef ADC_InitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;
  DMA_InitTypeDef DMA_InitStructure;

  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);

  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_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_NbrOfConversion = 1;
  ADC_Init(ADC1, &ADC_InitStructure);

  ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_3Cycles);

  ADC_DMARequestAfterLastTransferCmd(ADC1, ENABLE);

  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);

  DMA_InitStructure.DMA_Channel = DMA_Channel_0;
  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC1_DR_ADDRESS;
  DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&ADC1ConvertedValue;
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
  DMA_InitStructure.DMA_BufferSize = SampleCount;
  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);

  DMA_Cmd(DMA2_Stream0, ENABLE);

  ADC_DMARequestAfterLastTransferCmd(ADC1, ENABLE);

  ADC_Cmd(ADC1, ENABLE);
  ADC_DMACmd(ADC1, ENABLE);

  ADC_SoftwareStartConv(ADC1);
}

void TIM2_Init(void)
{
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

  TIM_TimeBaseStructure.TIM_Period = 999;
  TIM_TimeBaseStructure.TIM_Prescaler = 83;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

  TIM_Cmd(TIM2, ENABLE);
}

void GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;

  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOD, &GPIO_InitStructure);
}

void NVIC_Configuration(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;

  NVIC_InitStructure.NVIC_IRQChannel = DMA2_Stream0_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}

void DMA2_Stream0_IRQHandler(void)
{
  GPIO_SetBits(GPIOD, GPIO_Pin_14);

  DMA_ClearITPendingBit(DMA2_Stream0, DMA_IT_TC);
}

void Delay(__IO uint32_t nCount)
{
  while (nCount--)
  {
  }
}

void CalculateTHD(void)
{
  uint32_t i, j;
  float32_t maxValue = 0.0;
  float32_t squaredSum = 0.0;
  float32_t rmsValue = 0.0;

  for (i = 0; i < SampleCount; i++)
  {
    signal[i] = (float32_t)ADC1ConvertedValue[i] / 4095.0 * 3.3;
  }

  arm_rms_f32(signal, SampleCount, &rmsValue);

  for (j = 1; j <= 50; j++)
  {
    maxValue = 0.0;
    for (i = 0; i < SampleCount; i++)
    {
      harmonic[j] = harmonic[j] + signal[i] * arm_sin_f32(2.0 * PI * j * i / SampleCount);
    }
    harmonic[j] = harmonic[j] * 2.0 / SampleCount;
    for (i = 0; i < SampleCount; i++)
    {
      squaredSum = squaredSum + arm_power_f32((signal[i] - harmonic[j] * arm_sin_f32(2.0 * PI * j * i / SampleCount)), 2.0);
    }
    THD = THD + (uint32_t)(100 * (arm_sqrt_f32(squaredSum / SampleCount) / rmsValue));
  }
  THD = THD / 50;

  Delay(100);
}

该示例代码使用了 STM32 的 ADC 和 DMA 功能，采样 1024 个数据点，并通过计算得到了 THD 的值。该函数的实现过程如下：

1. 初始化 ADC 和 DMA，使其能够采样并存储数据。
2. 循环采样数据，计算其 RMS 值和谐波分量。
3. 计算 THD 值。

在计算 THD 值时，我们首先计算了每个谐波分量的值，然后计算了每个数据点与谐波分量之间的差值的平方和。最后，我们计算了 RMS 值并将其用作基准来计算 THD 值。

请注意，该示例代码仅供参考，并且可能需要根据你的具体应用场景进行修改。