基于HAL库，读取DHT11传感器温湿度数据的代码

以下是基于HAL库的DHT11传感器读取温湿度数据的示例代码：

#include "stm32f4xx_hal.h"

#define DHT11_PORT GPIOA
#define DHT11_PIN GPIO_PIN_0

void DHT11_Start(void);
uint8_t DHT11_Check(void);
uint8_t DHT11_ReadBit(void);
uint8_t DHT11_ReadByte(void);

int main(void)
{
  HAL_Init();
  __HAL_RCC_GPIOA_CLK_ENABLE();

  GPIO_InitTypeDef GPIO_InitStruct;
  GPIO_InitStruct.Pin = DHT11_PIN;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(DHT11_PORT, &GPIO_InitStruct);

  while (1)
  {
    DHT11_Start();

    if (DHT11_Check() == 0)
    {
      uint8_t humidity_int = DHT11_ReadByte();
      uint8_t humidity_dec = DHT11_ReadByte();
      uint8_t temperature_int = DHT11_ReadByte();
      uint8_t temperature_dec = DHT11_ReadByte();
      uint8_t check_sum = DHT11_ReadByte();

      if (humidity_int + humidity_dec + temperature_int + temperature_dec == check_sum)
      {
        float humidity = humidity_int + humidity_dec / 10.0f;
        float temperature = temperature_int + temperature_dec / 10.0f;
        // 处理温湿度数据
      }
    }

    HAL_Delay(2000);
  }
}

void DHT11_Start(void)
{
  HAL_GPIO_WritePin(DHT11_PORT, DHT11_PIN, GPIO_PIN_RESET);
  HAL_Delay(18);
  HAL_GPIO_WritePin(DHT11_PORT, DHT11_PIN, GPIO_PIN_SET);
  HAL_Delay(40);
  GPIO_InitStruct.Pin = DHT11_PIN;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(DHT11_PORT, &GPIO_InitStruct);
}

uint8_t DHT11_Check(void)
{
  uint8_t response = 0;
  uint16_t time_out = 0xFFFF;
  while (HAL_GPIO_ReadPin(DHT11_PORT, DHT11_PIN) == GPIO_PIN_SET)
  {
    time_out--;
    if (time_out == 0)
    {
      return 1;
    }
  }
  time_out = 0xFFFF;
  while (HAL_GPIO_ReadPin(DHT11_PORT, DHT11_PIN) == GPIO_PIN_RESET)
  {
    time_out--;
    if (time_out == 0)
    {
      return 1;
    }
  }
  time_out = 0xFFFF;
  while (HAL_GPIO_ReadPin(DHT11_PORT, DHT11_PIN) == GPIO_PIN_SET)
  {
    time_out--;
    if (time_out == 0)
    {
      return 1;
    }
  }
  return response;
}

uint8_t DHT11_ReadBit(void)
{
  uint8_t response = 0;
  uint16_t time_out = 0xFFFF;
  while (HAL_GPIO_ReadPin(DHT11_PORT, DHT11_PIN) == GPIO_PIN_RESET)
  {
    time_out--;
    if (time_out == 0)
    {
      return 1;
    }
  }
  time_out = 0xFFFF;
  while (HAL_GPIO_ReadPin(DHT11_PORT, DHT11_PIN) == GPIO_PIN_SET)
  {
    time_out--;
    if (time_out == 0)
    {
      return 1;
    }
  }
  if (time_out < 100)
  {
    response = 1;
  }
  return response;
}

uint8_t DHT11_ReadByte(void)
{
  uint8_t byte = 0;
  for (uint8_t i = 0; i < 8; i++)
  {
    byte <<= 1;
    byte |= DHT11_ReadBit();
  }
  return byte;
}

代码中，首先定义了DHT11传感器的GPIO引脚，然后在`main()`函数中初始化GPIO引脚，并循环读取温湿度数据。在每次读取时，调用`DHT11_Start()`函数进行DHT11传感器的开始信号发送，然后调用`DHT11_Check()`函数检查DHT11传感器的响应是否正确。如果响应正确，则调用`DHT11_ReadByte()`函数分别读取温度和湿度数据，并计算校验和进行校验。最后，在温湿度数据有效的情况下，可以将温湿度数据进行处理。

`DHT11_Start()`函数中，首先将DHT11引脚拉低18ms，然后拉高40us。接着，将DHT11引脚设为输入模式，并开启上拉电阻。

`DHT11_Check()`函数中，通过等待DHT11引脚由高电平变为低电平，再等待DHT11引脚由低电平变为高电平，最后等待DHT11引脚的响应信号结束，判断DHT11传感器的响应是否正确。

`DHT11_ReadBit()`函数中，等待DHT11引脚由低电平变为高电平，再等待DHT11引脚的高电平持续时间，判断读取到的数据是否为1。

`DHT11_ReadByte()`函数中，循环读取8位数据，并通过位移运算和按位或运算将各位数据组合成一个字节。