写一个串口三，连接esp8266使能串口发送和接收中断

好的，下面是一个使用USART3连接ESP8266，使能串口发送和接收中断的示例代码：

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

#define ESP8266_BUFFER_SIZE 64

volatile uint8_t esp8266_rx_buffer[ESP8266_BUFFER_SIZE];
volatile uint8_t esp8266_rx_index = 0;

void USART3_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_11;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    GPIO_PinAFConfig(GPIOB, GPIO_PinSource10, GPIO_AF_USART3);
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource11, GPIO_AF_USART3);

    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_Rx | USART_Mode_Tx;
    USART_Init(USART3, &USART_InitStructure);
    USART_Cmd(USART3, ENABLE);

    USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);

    NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

void ESP8266_SendString(char* str)
{
    while(*str)
    {
        while(USART_GetFlagStatus(USART3, USART_FLAG_TXE) == RESET);
        USART_SendData(USART3, *str++);
    }
}

void USART3_IRQHandler(void)
{
    if(USART_GetITStatus(USART3, USART_IT_RXNE) != RESET)
    {
        uint8_t ch = USART_ReceiveData(USART3);
        if(esp8266_rx_index < ESP8266_BUFFER_SIZE)
        {
            esp8266_rx_buffer[esp8266_rx_index++] = ch;
        }
    }
}

int main(void)
{
    USART3_Init();

    while(1)
    {
        // 发送AT指令
        ESP8266_SendString("AT\r\n");

        // 等待接收到ESP8266的回复
        while(esp8266_rx_index == 0);
        esp8266_rx_buffer[esp8266_rx_index] = '\0';

        // 处理接收到的数据
        printf("%s\n", esp8266_rx_buffer);

        // 清空接收缓存
        esp8266_rx_index = 0;
        memset(esp8266_rx_buffer, 0, sizeof(esp8266_rx_buffer));
    }
}

在该示例中，使用USART3连接ESP8266，初始化USART3模块，并使能USART3的接收中断。在USART3接收到数据后，将数据存储到esp8266_rx_buffer数组中，并递增esp8266_rx_index变量。在主循环中，发送AT指令给ESP8266，并等待接收到ESP8266的回复。当接收到数据后，使用printf函数输出到串口。然后清空接收缓存，以便下一次接收数据。