keil5中STM32F103使用RS485的中断函数

在Keil5中使用STM32F103的RS485通信，需要配置USART的中断函数。以下是一个示例代码：

#include "stm32f10x.h"

volatile uint8_t rx_buf[256];
volatile uint8_t tx_buf[256];
volatile uint8_t rx_len = 0;
volatile uint8_t tx_len = 0;

void USART1_IRQHandler(void)
{
    if (USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)
    {
        rx_buf[rx_len++] = USART_ReceiveData(USART1);
        if (rx_len >= 256)
            rx_len = 0;
    }
    if (USART_GetITStatus(USART1, USART_IT_TXE) != RESET)
    {
        if (tx_len > 0)
        {
            USART_SendData(USART1, tx_buf[0]);
            tx_buf++;
            tx_len--;
        }
        else
        {
            USART_ITConfig(USART1, USART_IT_TXE, DISABLE);
        }
    }
}

void USART1_Send(uint8_t *data, uint8_t len)
{
    while (tx_len > 0)
        ;
    memcpy(tx_buf, data, len);
    tx_len = len;
    USART_ITConfig(USART1, USART_IT_TXE, ENABLE);
}

int main(void)
{
    USART_InitTypeDef USART_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

    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);
    USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
    USART_Cmd(USART1, ENABLE);

    NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    while (1)
    {
        // do something
    }
}

在此示例中，我们使用`USART1`，并启用接收和发送中断。当接收到数据时，将数据存储在`rx_buf`缓冲区中，并增加`rx_len`计数器。当需要发送数据时，将数据复制到`tx_buf`缓冲区中，并将`tx_len`设置为数据长度。然后启用发送中断，并在中断处理程序中发送数据。当发送完成时，将禁用发送中断。

请注意，以上示例代码仅供参考，实际应用中需根据具体需求进行修改。