STM32F1 thd计算程序

以下是一个简单的STM32F1 THD计算程序：

#include "stm32f10x.h"

#define SAMPLES 256
#define PI 3.14159265359

uint16_t adc_buffer[SAMPLES];
float thd;

void GPIO_Configuration(void);
void ADC_Configuration(void);
void TIM_Configuration(void);

int main(void) {

  GPIO_Configuration();
  ADC_Configuration();
  TIM_Configuration();

  while (1) {

  }
}

void GPIO_Configuration(void) {

  // Configure PC0 as analog input
  GPIO_InitTypeDef GPIO_InitStructure;
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
  GPIO_Init(GPIOC, &GPIO_InitStructure);

}

void ADC_Configuration(void) {

  // Configure ADC1
  ADC_InitTypeDef ADC_InitStructure;
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
  ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
  ADC_InitStructure.ADC_ScanConvMode = DISABLE;
  ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
  ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_NbrOfChannel = 1;
  ADC_Init(ADC1, &ADC_InitStructure);

  // Configure ADC1 channel 10 (PC0)
  ADC_RegularChannelConfig(ADC1, ADC_Channel_10, 1, ADC_SampleTime_55Cycles5);

  // Enable ADC1
  ADC_Cmd(ADC1, ENABLE);

  // Start ADC1
  ADC_SoftwareStartConvCmd(ADC1, ENABLE);

}

void TIM_Configuration(void) {

  // Configure TIM2 for 1ms timer interrupt
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
  TIM_TimeBaseStructure.TIM_Period = 7199;
  TIM_TimeBaseStructure.TIM_Prescaler = 999;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

  // Enable TIM2 interrupt
  NVIC_InitTypeDef NVIC_InitStructure;
  NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);

  TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
  TIM_Cmd(TIM2, ENABLE);

}

void TIM2_IRQHandler(void) {

  if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET) {

    // Read ADC buffer
    for (int i = 0; i < SAMPLES; i++) {
      adc_buffer[i] = ADC_GetConversionValue(ADC1);
    }

    // Calculate THD
    float sum = 0;
    float fundamental = 0;
    for (int i = 0; i < SAMPLES; i++) {
      float value = (float)adc_buffer[i] / 4096.0 * 3.3;
      sum += value * value;
      if (i == 0) {
        fundamental = value;
      }
    }
    sum -= fundamental * fundamental;
    thd = sqrtf(sum) / fundamental;

    TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
  }

}

该程序配置了STM32F1的ADC和定时器，通过读取ADC缓冲区中的采样数据来计算THD。计算THD的过程是使用RMS计算基波和总谐波的平方和，然后除以基波的幅度，最后开平方根。在本例中，使用的是256个采样点，采样时间为55个时钟周期，采样频率为1.1kHz。