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    image.png

    附：NVIC初始化参数配置：

    1.     NVIC_InitTypeDef NVIC_InitStructure; //定义结构体
    2.     NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
    3.     NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3 ;  //抢占优先级 
    4.     NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;            //响应优先级
    5.     NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;        //使能NVIC分组