利用定时器4中断处理功能，实现每隔2s，读取实现将温湿度传感器的值上传到串口小助手

以下是一个利用定时器4中断处理功能实现每隔2s读取温湿度传感器并上传到串口小助手的示例代码：

#include <stm32f4xx.h>
#include <stdio.h>

#define DHT11_PORT  GPIOB
#define DHT11_PIN   GPIO_Pin_12

USART_InitTypeDef USART_InitStructure;

void TIM4_IRQHandler(void)
{
    static uint32_t count = 0;
    if (TIM_GetITStatus(TIM4, TIM_IT_Update) != RESET)
    {
        TIM_ClearITPendingBit(TIM4, TIM_IT_Update);
        count++;
        if (count == 1000) //2s
        {
            count = 0;
            float temperature = 0, humidity = 0;
            if (DHT11_Read_Temperature_Humidity(&temperature, &humidity) == 0)
            {
                char buffer[100];
                sprintf(buffer, "Temperature:%.1f Humidity:%.1f\r\n", temperature, humidity);
                USART_SendString(USART1, buffer);
            }
        }
    }
}

void USART_SendString(USART_TypeDef* USARTx, char* str)
{
    while (*str)
    {
        while (USART_GetFlagStatus(USARTx, USART_FLAG_TXE) == RESET);
        USART_SendData(USARTx, *str++);
    }
}

void USART_Configuration(void)
{
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

    USART_InitStructure.USART_BaudRate = 115200;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Tx;
    USART_Init(USART1, &USART_InitStructure);
    USART_Cmd(USART1, ENABLE);
}

void GPIO_Configuration(void)
{
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);

    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = DHT11_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(DHT11_PORT, &GPIO_InitStructure);
}

void TIM_Configuration(void)
{
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);

    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_TimeBaseStructure.TIM_Period = 1000 - 1; //计数器周期为1000
    TIM_TimeBaseStructure.TIM_Prescaler = 8400 - 1; //预分频器为8400，计数器时钟为10KHz
    TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);

    NVIC_InitTypeDef NVIC_InitStructure;
    NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    TIM_ITConfig(TIM4, TIM_IT_Update, ENABLE);
    TIM_Cmd(TIM4, ENABLE);
}

int main(void)
{
    USART_Configuration();
    GPIO_Configuration();
    TIM_Configuration();

    while (1);

    return 0;
}

在这个例子中，我们使用定时器4和中断处理函数来实现了每隔2s读取温湿度传感器并上传到串口小助手的功能。我们首先在中断处理函数中增加了一个count计数器，每次计数到1000时，即2s时，我们读取温湿度传感器的值并上传到串口小助手。在USART_SendString函数中，我们使用了USART1串口，可以根据实际情况修改。在GPIO_Configuration函数中，我们初始化了DHT11引脚为输出模式，并将其输出高电平。在TIM_Configuration函数中，我们设置计数器时钟和计数器周期，并使能了中断和计数器。