在stm32中是要配置nvic的。何为nvic，对于我这样的初学者来说，直观感受就是在设置为中断后 还需要配置 中断的优先级nvic就是搞这个的、
那么具体的需要配置些什么那？
void NVIC_Configuration(void)
{
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //设置NVIC中断分组2:2位抢占优先级，2位响应优先级
}
NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn; //使能按键WK_UP所在的外部中断通道
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02; //抢占优先级2，
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x03; //子优先级3
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //使能外部中断通道
NVIC_Init(&NVIC_InitStructure);
STM32有43个channel的settable的中断源；AIRC(Application Interrupt and Reset Register)寄存器中有用于指定优先级的4 bits。这4个bits用于分配preemption优先级和sub优先级，在STM32的固件库中定义如下
#define NVIC_PriorityGroup_0 ((u32)0x700)
#define NVIC_PriorityGroup_1 ((u32)0x600)
#define NVIC_PriorityGroup_2 ((u32)0x500)
#define NVIC_PriorityGroup_3 ((u32)0x400)
#define NVIC_PriorityGroup_4 ((u32)0x300)
每个工程只能有一种分组方式：
按NVIC_PriorityGroup_0来分组：抢占优先级为1个，子优先级为16个；
按NVIC_PriorityGroup_1来分组：抢占优先级为2个，子优先级为8个；
按NVIC_PriorityGroup_2来分组：抢占优先级为4个，子优先级为4个；
按NVIC_PriorityGroup_3来分组：抢占优先级为8个，子优先级为2个；
按NVIC_PriorityGroup_0来分组：抢占优先级为16个，子优先级为1个；
抢占优先级高的中断可以打断抢占优先级低的中断；抢占优先级相同时比较响应优先级（子优先级）。
先设定分组方式
例：NVIC_PriorityGroupConfig(NVIC_PriorityGroup_4); //按NVIC_PriorityGroup_4来分组
此时，有一中断EXTI0_IRQChannel，你指定他为抢占优先级8，则
NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 8; // 指定抢占式优先级别，可取0-15
又有1中断SPI1_IRQChannel，设定如下
NVIC_InitStructure.NVIC_IRQChannel = SPI1_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; // 指定抢占式优先级别，可取0-15
则SPI1_IRQChannel的抢占优先级高，EXTI0_IRQChannel做事的时候可以打断（嵌套）
又：若分组方式为：NVIC_PriorityGroupConfig(NVIC_PriorityGroup_3); //按NVIC_PriorityGroup_3来分组
此时就有8个抢占优先级，2个子优先级；
EXTI0_IRQChannel中断，你指定他为抢占优先级3，则：
NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; // 指定抢占式优先级别，可取0-7
还需要指定他的阶层：
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; // 指定响应优先级别，可取0-1
又有TIM2_IRQn中断，设定如下：
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;// 指定抢占式优先级别，可取0-7
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; // 指定响应优先级别，可取0-1
由于抢占优先级相同，响应优先级EXTI0_IRQChannel中断高于TIM2_IRQn中断，所以EXTI0_IRQChannel可以打断TIM2_IRQn；
还有一USB_LP_CAN1_RX0_IRQn，设定如下：
NVIC_InitStructure.NVIC_IRQChannel = USB_LP_CAN1_RX0_IRQn; //CAN1 RX0中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //抢占优先级0
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //响应优先级别0，可取0-1
USB_LP_CAN1_RX0_IRQn优先级最高，前两中断发生时，它都可以打断。
附：
void NVIC_Config(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_3);//一个工程中只能使用一种分组方式
NVIC_InitStructure.NVIC_IRQChannel = USB_LP_CAN1_RX0_IRQn; //CAN1 RX0中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //抢占优先级0
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //子优先级为0
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;// 指定抢占式优先级别，可取0-7
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; // 指定响应优先级别，可取0-1
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; // 指定抢占式优先级别，可取0-7
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; // 指定响应优先级别，可取0-1
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}