rs485自动收发通信程序

Question

#32驱动RS485，没有反应，硬件电路设计的是自动收发的电路，有没有人知道，该如何配置这种情况的串口？

USART_SendData(USART3,0x0d);
    while(USART_GetFlagStatus(USART3,USART_FLAG_TXE) == RESET);

void usart_485_init(void)
{    
    USART_InitTypeDef USART_InitStructure;
    NVIC_InitTypeDef   NVIC_InitStructure;
    GPIO_InitTypeDef   GPIO_InitStructure;
    
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3,ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);        //打开USART1的时钟
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE); 
    
    /*USART3_TX -> PB10 , USART3_RX -> PB11 ,  PB10,低电平进入发送模式，高电平进入接收模式
    当TX高电平，mos管导通，RE和DE引脚接地，进入接收模式。当TX低电平，mos管截止，RE和DE引脚接高电平，进入发送模式*/
    GPIO_InitStructure.GPIO_Mode     = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Pin     = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Speed     = GPIO_Speed_50MHz;    
    GPIO_Init(GPIOB,&GPIO_InitStructure);
    
    GPIO_InitStructure.GPIO_Mode     = GPIO_Mode_IN_FLOATING;
    GPIO_InitStructure.GPIO_Pin     = GPIO_Pin_11;
    GPIO_Init(GPIOB,&GPIO_InitStructure);
    
    GPIO_PinRemapConfig(GPIO_PartialRemap_USART3,ENABLE);
    
    NVIC_InitStructure.NVIC_IRQChannel                         = USART3_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority     = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority             = 1;
    NVIC_InitStructure.NVIC_IRQChannelCmd                     = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
    
    USART_DeInit(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_Tx|USART_Mode_Rx;
    USART_Init(USART3,&USART_InitStructure);
    
    //USART_ClearFlag(USART3,USART_IT_RXNE);    //清除中断标志
    USART_ITConfig(USART3,USART_IT_RXNE,ENABLE);    //设置中断方式
    USART_Cmd(USART3,ENABLE);    //使能终端    
}

使用485转USB发送无反应

Answer 1

• 这篇文章：关于RS485的使用 也许能够解决你的问题，你可以看下