GP2Y1010AU的STM32驱动

#define WINDOW_SIZE 32

int movingAverage(int newSample)
{
  static int samples[WINDOW_SIZE] = {0};
  static int index = 0;
  static int sum = 0;

  sum -= samples[index];
  samples[index] = newSample;
  sum += newSample;

  index = (index + 1) & (WINDOW_SIZE - 1);

  return sum >> 5;
}
void pm25_task() {
	// 自己电路接的LED Pin，我这是PA4
	// 按照下图1，2，需要10ms一个脉冲驱动LED，等280us后可以测得输出电压
	// ADC增加滑动平均
	// 计算PM2.5是通过图3的曲线拟合
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
  delayus(280);
  HAL_ADC_Start(&hadc1);
  HAL_ADC_PollForConversion(&hadc1, 50);
  if(HAL_IS_BIT_SET(HAL_ADC_GetState(&hadc1), HAL_ADC_STATE_REG_EOC))
  {
    adc_value = HAL_ADC_GetValue(&hadc1);   //获取AD值
  }
  adc_value = movingAverage(adc_value);
  delayus(40);
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
}
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim){
  // 10ms interrupt
  if(htim->Instance == TIM2){
    pm25_task();
  }
}
float cal_pm25(float voltageRead)
{
  if (voltageRead < 0.9)
  {
    voltageRead = 0.9;
  }
  else if (voltageRead > 3.4)
  {
    voltageRead = 3.4;
  }
  return 180 * voltageRead - 162;
}

float pm25 = 0;
pm25 = adc_value * 3.3 / 4096;
pm25 = cal_pm25(pm25);