stm32如何与esp8266通信，请用标准库展示实现代码示例

如果使用标准库实现，可以使用USART串口通信来实现STM32与ESP8266的通信。以下是示例代码：

#include "stm32f10x.h"

void USART1_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    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(USART1, &USART_InitStructure);

    USART_Cmd(USART1, ENABLE);
}

void USART1_Write(uint16_t data)
{
    while (!(USART1->SR & USART_SR_TC));
    USART1->DR = (data & 0xFF);
}

uint16_t USART1_Read(void)
{
    while (!(USART1->SR & USART_SR_RXNE));
    return (USART1->DR & 0xFF);
}

int main(void)
{
    USART1_Init();

    while (1)
    {
        USART1_Write('A'); // 发送数据
        uint16_t data = USART1_Read(); // 接收数据
    }
}

在此基础上，可以使用AT指令来控制ESP8266进行WiFi连接等操作。具体的AT指令可以参考ESP8266的官方文档。