中断优先级

yilusuiyuan

/*配置中断引脚*/
void exti_config(void)
{
//GPIO_InitTypeDef GPIO_InitStructure;
EXTI_InitTypeDef EXTI_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
//设置NVIC优先级分组为Group2：2位先占优先级（0-2），2位子优先级（0-2）

GPIO_EXTILineConfig(button_port_source,button1_source);    //选择按键1的GPIO管脚（端口+管脚号）做外中断源
GPIO_EXTILineConfig(button_port_source,button2_source);    //选择按键2的GPIO管脚（端口+管脚号）做外中断源

EXTI_InitStructure.EXTI_Line = button1_exti_line|button2_exti_line; //设置按键所有的外部线路
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt; //设置为外部中断模式
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;      //设置触发模式为下降沿触发
EXTI_InitStructure.EXTI_LineCmd = ENABLE; //使能该线路中断
EXTI_Init(&EXTI_InitStructure);

NVIC_InitStructure.NVIC_IRQChannel = button_irqn; //使能按键所在的外部中断通道
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x00; //
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;       //从优先级15
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //使能外部中断通道
NVIC_Init(&NVIC_InitStructure); //根据NVIC_InitStruct中指定的参数初始化外设NVIC寄存器

   GPIO_EXTILineConfig(button_wakeup_gpio_source, button_wakeup_source);

EXTI_InitStructure.EXTI_Line = button_wakeup_exti_line ; //设置按键所有的外部线路
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt; //设外外部中断模式:EXTI线路为中断请求
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
EXTI_InitStructure.EXTI_LineCmd = ENABLE; //使能外部中断新状态
EXTI_Init(&EXTI_InitStructure);

    NVIC_InitStructure.NVIC_IRQChannel = button_wakeup_irqn; //使能按键所在的外部中断通道
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x00; //抢占优先级
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x02; //从优先级2
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //使能外部中断通道
NVIC_Init(&NVIC_InitStructure); //根据NVIC_InitStruct中指定的参数初始化外设NVIC寄存器
}

既然NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);设置能了2位，2位，为何NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x00; //
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;       //从优先级15这里有个15，个人理解2位最大为4吧。求解释？