STM32之NVIC理解.doc

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 0-7NVIC_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 0NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //响应优先级别 0，可取 0-1USB_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 0NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //子优先级为 0NVIC_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 0-7NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; // 指定响应优先级别，可取 0-1NVIC_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 0-7NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; // 指定响应优先级别，可取 0-1NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_InitStructure);}。