stm32 RS485 SP3485

柔情只为你懂 2022-06-09 19:57 233阅读 0赞

RS485 是半双工通信（2 线制）

![1][]  
SP3485芯片的DE与RE短接在一起连接在STM32F1芯片的PG3上，通过PG3管脚就可以控制 SP3485的收发，当PG3=0时，为接收模式，当PG3=1时，为发送模式

![2][]

![3][]

![4][]

`相关文章:`[http://blog.csdn.net/zhangxuechao\_/article/details/77095985][http_blog.csdn.net_zhangxuechao_article_details_77095985]

**举例**

void USART2_IRQHandler()
    {
        u8 r;
    
        if(USART_GetITStatus(USART2, USART_IT_RXNE) == SET)
        {
            r = USART_ReceiveData(USART2);
    
            rs485 = 1; //使能发送
            delay_ms(1);
            USART_SendData(USART2, r);
    
            led1 = ~led1;
    
            while(USART_GetFlagStatus(USART2, USART_FLAG_TC) != SET);       
            rs485 = 0;
        }
    
        USART_ClearFlag(USART2, USART_FLAG_TC);
    }
    
    void RS485_init()
    {
        GPIO_InitTypeDef gpiog3 = 
        {
            GPIO_Pin_3,
            GPIO_Speed_50MHz,
            GPIO_Mode_Out_PP //推挽输出
        };  
    
        GPIO_InitTypeDef gpioa2 = 
        {
            GPIO_Pin_2,
            GPIO_Speed_50MHz,
            GPIO_Mode_AF_PP //复用推挽输出
        };
    
        GPIO_InitTypeDef gpioa3 = 
        {
            GPIO_Pin_3,
            GPIO_Speed_50MHz,
            GPIO_Mode_IN_FLOATING //模拟输入
        };
    
        NVIC_InitTypeDef nvic = 
        {
            USART2_IRQn,
            2,
            2,
            ENABLE
        };
    
        USART_InitTypeDef usart = 
        {
            9600,
            USART_WordLength_8b,
            USART_StopBits_1,
            USART_Parity_No,
            USART_Mode_Rx | USART_Mode_Tx,
            USART_HardwareFlowControl_None, //硬件流控制
        };
    
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOG, ENABLE);
        RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
    
        GPIO_Init(GPIOG, &gpiog3);
        GPIO_Init(GPIOA, &gpioa2);
        GPIO_Init(GPIOA, &gpioa3);
    
        USART_Init(USART2, &usart);
    
        USART_Cmd(USART2, ENABLE);
    
        USART_ITConfig(USART2, USART_IT_RXNE, ENABLE); 
    
        NVIC_Init(&nvic);
    
        rs485 = 0; //默认接收
    }

[1]: /images/20220610/8a4735c8bdc94eeb8bc41258a4d0940b.png
[2]: /images/20220610/78336d97c8d6498f9adb4fb55f01dbc8.png
[3]: /images/20220610/94955385c91240a191e0ad816113cae5.png
[4]: /images/20220610/a01d25a417c4497298988f21210e9c79.png
[http_blog.csdn.net_zhangxuechao_article_details_77095985]: http://blog.csdn.net/zhangxuechao_/article/details/77095985