基于stm32f103的rs485通信代码

以下是基于STM32F103的RS485通信代码，可以作为参考：

#include "stm32f10x.h"

#define RS485_PORT      GPIOA
#define RS485_PIN       GPIO_Pin_1

#define USART_PORT      GPIOA
#define USART_PIN_TX    GPIO_Pin_9
#define USART_PIN_RX    GPIO_Pin_10

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

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_USART1, ENABLE);

    GPIO_InitStructure.GPIO_Pin = USART_PIN_TX;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(USART_PORT, &GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Pin = USART_PIN_RX;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(USART_PORT, &GPIO_InitStructure);

    USART_InitStructure.USART_BaudRate = 9600;
    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 GPIO_RS485_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

    GPIO_InitStructure.GPIO_Pin = RS485_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(RS485_PORT, &GPIO_InitStructure);

    GPIO_ResetBits(RS485_PORT, RS485_PIN);
}

void RS485_SendByte(uint8_t byte)
{
    USART_SendData(USART1, byte);
    while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET);
}

void RS485_SendData(uint8_t *buf, uint8_t len)
{
    GPIO_SetBits(RS485_PORT, RS485_PIN);

    for(uint8_t i = 0; i < len; i++)
    {
        RS485_SendByte(buf[i]);
    }

    GPIO_ResetBits(RS485_PORT, RS485_PIN);
}

int main()
{
    USART1_Init();
    GPIO_RS485_Init();

    uint8_t buf[] = {0x01, 0x02, 0x03, 0x04, 0x05};
    RS485_SendData(buf, sizeof(buf));

    while(1);

    return 0;
}

在此代码中，我们使用了USART1作为RS485通信的串口，使用GPIOA和PA1作为RS485的控制引脚。在初始化函数中，我们初始化了USART1和GPIOA，设置了波特率为9600，数据位为8位，停止位为1位，无校验位。在发送函数中，我们首先拉高控制引脚，然后逐个发送字节，最后再拉低控制引脚。在主函数中，我们初始化USART1和GPIOA，发送了一个数据包，然后进入了一个死循环。