stm32f4ADC测方波占空比

你可以通过以下步骤使用STM32F4的ADC来测量方波占空比：

1. 配置GPIO口作为输入，连接方波信号。
2. 配置TIM定时器来产生一个与方波频率相同的定时器中断。
3. 在定时器中断中读取GPIO口状态来确定方波的占空比。
4. 使用ADC采集器件读取占空比的值。

以下是一个简单的示例代码：

#include "stm32f4xx.h"

#define TIM_PERIOD   1000 // 定时器周期
#define SAMPLE_NUM   100  // 采样次数

GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_ICInitTypeDef TIM_ICInitStructure;
ADC_InitTypeDef ADC_InitStructure;

uint16_t sample[SAMPLE_NUM];

void GPIO_Configuration(void)
{
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_TIM2);
}

void TIM_Configuration(void)
{
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

  TIM_TimeBaseStructure.TIM_Period = TIM_PERIOD - 1;
  TIM_TimeBaseStructure.TIM_Prescaler = 84 - 1;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

  TIM_ICStructInit(&TIM_ICInitStructure);
  TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
  TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
  TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
  TIM_ICInitStructure.TIM_ICFilter = 0x0;
  TIM_ICInit(TIM2, &TIM_ICInitStructure);

  TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);

  TIM_Cmd(TIM2, ENABLE);
}

void ADC_Configuration(void)
{
  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_Cmd(ADC1, ENABLE);

  ADC_SoftwareStartConv(ADC1);
}

int main(void)
{
  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);

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

  while (1)
  {
    for (int i = 0; i < SAMPLE_NUM; i++)
    {
      while (ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET);
      sample[i] = ADC_GetConversionValue(ADC1);
    }

    uint32_t sum = 0;
    for (int i = 0; i < SAMPLE_NUM; i++)
    {
      sum += sample[i];
    }

    uint32_t average = sum / SAMPLE_NUM;

    if (average > (TIM_PERIOD / 2))
    {
      GPIO_SetBits(GPIOD, GPIO_Pin_12);
    }
    else
    {
      GPIO_ResetBits(GPIOD, GPIO_Pin_12);
    }

    ADC_SoftwareStartConv(ADC1);
  }
}

在这个例子中，我们使用PA0口来读取方波信号，TIM2来产生定时器中断，并使用ADC1来读取占空比的值。我们使用GPIO口PD12来表示方波的高电平状态。当占空比大于50%时，PD12电平为高，否则为低。