怎么实现STM32F103RCT6上使用串口通信来发送AT指令给ESP8266，代码实现

可以使用STM32F103RCT6的USART模块来实现串口通信，并调用相应的函数来发送AT指令给ESP8266模块。以下是代码实现的示例：

首先需要在代码中包含所需的头文件：

#include "stm32f10x.h"
#include <stdio.h>
#include <string.h>

然后定义所需的变量：

USART_InitTypeDef USART_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
DMA_InitTypeDef DMA_InitStructure;
uint8_t  USART_RxBuffer[255];
uint8_t temp[255] = "";
uint16_t USART_Rx_Count = 0;

接下来是初始化GPIO和USART的代码：

void init_USART1_GPIO(void)
{
  RCC_APB2PeriphClockCmd(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_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
}

void init_USART1(uint32_t baudrate)
{
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

  USART_InitStructure.USART_BaudRate = baudrate;
  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_Mode_Rx;

  USART_Init(USART1, &USART_InitStructure);

  USART_Cmd(USART1, ENABLE);
}

接着，使用DMA发送AT指令：

void DMA_Configuration(uint8_t *buffer, uint32_t buffer_size)
{
  DMA_DeInit(DMA1_Channel4);

  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) & (USART1->DR);
  DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t) buffer;
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
  DMA_InitStructure.DMA_BufferSize = buffer_size;
  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
  DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
  DMA_InitStructure.DMA_Priority = DMA_Priority_High;
  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

  DMA_Init(DMA1_Channel4, &DMA_InitStructure);

  DMA_Cmd(DMA1_Channel4, ENABLE);
}

void send_AT_command(uint8_t *data, uint16_t len)
{
  while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET);
  memcpy(temp, data, len);

  DMA_Configuration(temp, len);

  while (DMA_GetFlagStatus(DMA1_FLAG_TC4) == RESET);

  DMA_ClearFlag(DMA1_FLAG_TC4);

  memset(temp, 0x00, sizeof(temp));
}

最后，调用send_AT_command函数来发送AT指令给ESP8266：

send_AT_command("AT\r\n", sizeof("AT\r\n")); // 发送AT指令

以上代码仅供参考，具体实现要根据实际需求进行修改。