基于stm32写一个rs485通讯代码

由于您没有提供具体的通讯协议和硬件连接方式，因此无法为您提供完整的代码。以下是一个基本的RS485通讯代码框架，供您参考：

#include "stm32f10x.h"
#include "stm32f10x_usart.h"
#include "stm32f10x_gpio.h"
#include "stm32f10x_rcc.h"

#define RS485_DIR_GPIO_PORT  GPIOA
#define RS485_DIR_GPIO_PIN   GPIO_Pin_8

void RS485_SendData(uint8_t* data, uint16_t len);
void RS485_SetDirection(uint8_t dir);

int main(void)
{
  USART_InitTypeDef USART_InitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;

  // Enable USART1 and GPIOA clock
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);

  // Configure USART1 TX (PA9) and RX (PA10) as alternate function push-pull
  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);

  // Configure RS485 direction control pin (PA8) as output push-pull
  GPIO_InitStructure.GPIO_Pin = RS485_DIR_GPIO_PIN;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(RS485_DIR_GPIO_PORT, &GPIO_InitStructure);

  // Configure USART1 for 115200 baud rate, 8 data bits, no parity, 1 stop bit
  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);

  // Enable USART1
  USART_Cmd(USART1, ENABLE);

  while (1)
  {
    uint8_t data[] = {0x01, 0x02, 0x03, 0x04};
    RS485_SendData(data, sizeof(data));
    delay_ms(1000);
  }
}

void RS485_SendData(uint8_t* data, uint16_t len)
{
  RS485_SetDirection(1); // Set direction to transmit
  for (uint16_t i = 0; i < len; i++)
  {
    USART_SendData(USART1, data[i]);
    while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET); // Wait until data is sent
  }
  while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); // Wait until transmission is complete
  RS485_SetDirection(0); // Set direction to receive
}

void RS485_SetDirection(uint8_t dir)
{
  if (dir)
  {
    GPIO_SetBits(RS485_DIR_GPIO_PORT, RS485_DIR_GPIO_PIN);
  }
  else
  {
    GPIO_ResetBits(RS485_DIR_GPIO_PORT, RS485_DIR_GPIO_PIN);
  }
}

该代码框架使用USART1作为RS485通讯口，PA9作为TX引脚，PA10作为RX引脚，PA8作为RS485方向控制引脚。其中，RS485_SendData函数用于发送数据，RS485_SetDirection用于设置方向控制引脚状态。在使用时，您需要根据具体的通讯协议和硬件连接方式进行相应的修改。