STM32F4X NVIC中断概念
- CPU查询状态两种方式
- 轮询查询
- 中断查询
- STM32有关中断的概念
- 中断向量表
- 系统中断
- 外设中断
- 中断号
- 中断优先级
- STM32F4X NVIC控制器
- NVIC控制器简介
- NVIC寄存器
- 优先级分组
- STM32F4X中断配置
- 优先级分组设置
- 配置外设中断
CPU查询状态两种方式
在讲解中断的概念之前，先了解一些CPU查询状态的两种方法，分别是轮询查询和中断查询。
轮询查询
轮询查询的方法是在规定的时间内循环查询某个外设的状态。举个日常生活的例子来做进一步的说明，比如你的朋友告诉你早上要到你家拜访，但是没说具体的拜访时间，在早上的那段时间你正在打扫卫生，因为你不知到你的朋友什么时候到，所以你必须每隔一段时间，比如每隔10分钟就开门查看一次，看你朋友是否已经到。类比到CPU也是一样的道理，比如串口需要接收一个数据，如果使用轮询的方式，CPU就必须每隔一段时间去查询串口接收寄存器的标志位是否有数据，如果没有就继续等待下一次时间继续查询，如果有就读取数据。轮询查询的缺点就是CPU需要频繁读取外设状态，很耗CPU的时间。
中断查询
中断查询的意思就是当某个外设有数据时，就会给CPU发一个信号，告诉CPU有数据到了，要处理，在外设没有给信号的时间，CPU可以去做其他的事情。同样用上面的生活例子做个说明，你的朋友告诉你早上要到你家拜访，没说具体的拜访时间，但是你告诉他如果到了就按下门铃，因为有门铃这个信号，所以当门铃没有响的时候，就代表朋友没有到，你可以去做其他的事情，不用再去频繁开门看你朋友是否已经到，当门铃响的时候，就代表朋友到了，这时候才去开门。
所以中断就是CPU可以暂停当前的工作，去执行中断处理函数中的任务，处理完之后再继续执行暂停的工作。
STM32有关中断的概念
中断向量表
在STM32F4的启动文件中，定义了STM32F4这款芯片的中断向量表，其中包含了16个系统中断和82个外设中断。中断向量表的作用是给MCU的所有中断服务函数都设置一个地址，这样中断到的时候CPU就会到相应的地址去执行中断服务函数。
系统中断
无论是哪一家MCU厂商，只要是用Crotex-M4的架构，其系统中断都是一样的，MCU厂商不能改变系统中断。
DCD __initial_sp ; Top of Stack
DCD Reset_Handler ; Reset Handler
DCD NMI_Handler ; NMI Handler
DCD HardFault_Handler ; Hard Fault Handler
DCD MemManage_Handler ; MPU Fault Handler
DCD BusFault_Handler ; Bus Fault Handler
DCD UsageFault_Handler ; Usage Fault Handler
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD 0 ; Reserved
DCD SVC_Handler ; SVCall Handler
DCD DebugMon_Handler ; Debug Monitor Handler
DCD 0 ; Reserved
DCD PendSV_Handler ; PendSV Handler
DCD SysTick_Handler ; SysTick Handler
外设中断
外设中断是每家MCU厂商自己设计的，不同的MCU都有自己不同的外设，所以外设中断也会不同，STM32F4定义82个外设中断。
DCD WWDG_IRQHandler ; Window WatchDog
DCD PVD_IRQHandler ; PVD through EXTI Line detection
DCD TAMP_STAMP_IRQHandler ; Tamper and TimeStamps through the EXTI line
DCD RTC_WKUP_IRQHandler ; RTC Wakeup through the EXTI line
DCD FLASH_IRQHandler ; FLASH
DCD RCC_IRQHandler ; RCC
DCD EXTI0_IRQHandler ; EXTI Line0
DCD EXTI1_IRQHandler ; EXTI Line1
DCD EXTI2_IRQHandler ; EXTI Line2
DCD EXTI3_IRQHandler ; EXTI Line3
DCD EXTI4_IRQHandler ; EXTI Line4
DCD DMA1_Stream0_IRQHandler ; DMA1 Stream 0
DCD DMA1_Stream1_IRQHandler ; DMA1 Stream 1
DCD DMA1_Stream2_IRQHandler ; DMA1 Stream 2
DCD DMA1_Stream3_IRQHandler ; DMA1 Stream 3
DCD DMA1_Stream4_IRQHandler ; DMA1 Stream 4
DCD DMA1_Stream5_IRQHandler ; DMA1 Stream 5
DCD DMA1_Stream6_IRQHandler ; DMA1 Stream 6
DCD ADC_IRQHandler ; ADC1, ADC2 and ADC3s
DCD CAN1_TX_IRQHandler ; CAN1 TX
DCD CAN1_RX0_IRQHandler ; CAN1 RX0
DCD CAN1_RX1_IRQHandler ; CAN1 RX1
DCD CAN1_SCE_IRQHandler ; CAN1 SCE
DCD EXTI9_5_IRQHandler ; External Line[9:5]s
DCD TIM1_BRK_TIM9_IRQHandler ; TIM1 Break and TIM9
DCD TIM1_UP_TIM10_IRQHandler ; TIM1 Update and TIM10
DCD TIM1_TRG_COM_TIM11_IRQHandler ; TIM1 Trigger and Commutation and TIM11
DCD TIM1_CC_IRQHandler ; TIM1 Capture Compare
DCD TIM2_IRQHandler ; TIM2
DCD TIM3_IRQHandler ; TIM3
DCD TIM4_IRQHandler ; TIM4
DCD I2C1_EV_IRQHandler ; I2C1 Event
DCD I2C1_ER_IRQHandler ; I2C1 Error
DCD I2C2_EV_IRQHandler ; I2C2 Event
DCD I2C2_ER_IRQHandler ; I2C2 Error
DCD SPI1_IRQHandler ; SPI1
DCD SPI2_IRQHandler ; SPI2
DCD USART1_IRQHandler ; USART1
DCD USART2_IRQHandler ; USART2
DCD USART3_IRQHandler ; USART3
DCD EXTI15_10_IRQHandler ; External Line[15:10]s
DCD RTC_Alarm_IRQHandler ; RTC Alarm (A and B) through EXTI Line
DCD OTG_FS_WKUP_IRQHandler ; USB OTG FS Wakeup through EXTI line
DCD TIM8_BRK_TIM12_IRQHandler ; TIM8 Break and TIM12
DCD TIM8_UP_TIM13_IRQHandler ; TIM8 Update and TIM13
DCD TIM8_TRG_COM_TIM14_IRQHandler ; TIM8 Trigger and Commutation and TIM14
DCD TIM8_CC_IRQHandler ; TIM8 Capture Compare
DCD DMA1_Stream7_IRQHandler ; DMA1 Stream7
DCD FSMC_IRQHandler ; FSMC
DCD SDIO_IRQHandler ; SDIO
DCD TIM5_IRQHandler ; TIM5
DCD SPI3_IRQHandler ; SPI3
DCD UART4_IRQHandler ; UART4
DCD UART5_IRQHandler ; UART5
DCD TIM6_DAC_IRQHandler ; TIM6 and DAC1&2 underrun errors
DCD TIM7_IRQHandler ; TIM7
DCD DMA2_Stream0_IRQHandler ; DMA2 Stream 0
DCD DMA2_Stream1_IRQHandler ; DMA2 Stream 1
DCD DMA2_Stream2_IRQHandler ; DMA2 Stream 2
DCD DMA2_Stream3_IRQHandler ; DMA2 Stream 3
DCD DMA2_Stream4_IRQHandler ; DMA2 Stream 4
DCD ETH_IRQHandler ; Ethernet
DCD ETH_WKUP_IRQHandler ; Ethernet Wakeup through EXTI line
DCD CAN2_TX_IRQHandler ; CAN2 TX
DCD CAN2_RX0_IRQHandler ; CAN2 RX0
DCD CAN2_RX1_IRQHandler ; CAN2 RX1
DCD CAN2_SCE_IRQHandler ; CAN2 SCE
DCD OTG_FS_IRQHandler ; USB OTG FS
DCD DMA2_Stream5_IRQHandler ; DMA2 Stream 5
DCD DMA2_Stream6_IRQHandler ; DMA2 Stream 6
DCD DMA2_Stream7_IRQHandler ; DMA2 Stream 7
DCD USART6_IRQHandler ; USART6
DCD I2C3_EV_IRQHandler ; I2C3 event
DCD I2C3_ER_IRQHandler ; I2C3 error
DCD OTG_HS_EP1_OUT_IRQHandler ; USB OTG HS End Point 1 Out
DCD OTG_HS_EP1_IN_IRQHandler ; USB OTG HS End Point 1 In
DCD OTG_HS_WKUP_IRQHandler ; USB OTG HS Wakeup through EXTI
DCD OTG_HS_IRQHandler ; USB OTG HS
DCD DCMI_IRQHandler ; DCMI
DCD CRYP_IRQHandler ; CRYP crypto
DCD HASH_RNG_IRQHandler ; Hash and Rng
DCD FPU_IRQHandler ; FPU
中断号
中断号可以理解成每个中断的索引，是给用户使用的，中断号要跟中断向量表中的中断服务函数一一对应，在STM32F4中，中断号定义在stm32f4xx.h中
NonMaskableInt_IRQn = -14, /*!< 2 Non Maskable Interrupt */
MemoryManagement_IRQn = -12, /*!< 4 Cortex-M4 Memory Management Interrupt */
BusFault_IRQn = -11, /*!< 5 Cortex-M4 Bus Fault Interrupt */
UsageFault_IRQn = -10, /*!< 6 Cortex-M4 Usage Fault Interrupt */
SVCall_IRQn = -5, /*!< 11 Cortex-M4 SV Call Interrupt */
DebugMonitor_IRQn = -4, /*!< 12 Cortex-M4 Debug Monitor Interrupt */
PendSV_IRQn = -2, /*!< 14 Cortex-M4 Pend SV Interrupt */
SysTick_IRQn = -1, /*!< 15 Cortex-M4 System Tick Interrupt */
/****** STM32 specific Interrupt Numbers **********************************************************************/
WWDG_IRQn = 0, /*!< Window WatchDog Interrupt */
PVD_IRQn = 1, /*!< PVD through EXTI Line detection Interrupt */
TAMP_STAMP_IRQn = 2, /*!< Tamper and TimeStamp interrupts through the EXTI line */
RTC_WKUP_IRQn = 3, /*!< RTC Wakeup interrupt through the EXTI line */
FLASH_IRQn = 4, /*!< FLASH global Interrupt */
RCC_IRQn = 5, /*!< RCC global Interrupt */
EXTI0_IRQn = 6, /*!< EXTI Line0 Interrupt */
EXTI1_IRQn = 7, /*!< EXTI Line1 Interrupt */
EXTI2_IRQn = 8, /*!< EXTI Line2 Interrupt */
EXTI3_IRQn = 9, /*!< EXTI Line3 Interrupt */
EXTI4_IRQn = 10, /*!< EXTI Line4 Interrupt */
DMA1_Stream0_IRQn = 11, /*!< DMA1 Stream 0 global Interrupt */
DMA1_Stream1_IRQn = 12, /*!< DMA1 Stream 1 global Interrupt */
DMA1_Stream2_IRQn = 13, /*!< DMA1 Stream 2 global Interrupt */
DMA1_Stream3_IRQn = 14, /*!< DMA1 Stream 3 global Interrupt */
DMA1_Stream4_IRQn = 15, /*!< DMA1 Stream 4 global Interrupt */
DMA1_Stream5_IRQn = 16, /*!< DMA1 Stream 5 global Interrupt */
DMA1_Stream6_IRQn = 17, /*!< DMA1 Stream 6 global Interrupt */
ADC_IRQn = 18, /*!< ADC1, ADC2 and ADC3 global Interrupts */
CAN1_TX_IRQn = 19, /*!< CAN1 TX Interrupt */
CAN1_RX0_IRQn = 20, /*!< CAN1 RX0 Interrupt */
CAN1_RX1_IRQn = 21, /*!< CAN1 RX1 Interrupt */
CAN1_SCE_IRQn = 22, /*!< CAN1 SCE Interrupt */
EXTI9_5_IRQn = 23, /*!< External Line[9:5] Interrupts */
TIM1_BRK_TIM9_IRQn = 24, /*!< TIM1 Break interrupt and TIM9 global interrupt */
TIM1_UP_TIM10_IRQn = 25, /*!< TIM1 Update Interrupt and TIM10 global interrupt */
TIM1_TRG_COM_TIM11_IRQn = 26, /*!< TIM1 Trigger and Commutation Interrupt and TIM11 global interrupt */
TIM1_CC_IRQn = 27, /*!< TIM1 Capture Compare Interrupt */
TIM2_IRQn = 28, /*!< TIM2 global Interrupt */
TIM3_IRQn = 29, /*!< TIM3 global Interrupt */
TIM4_IRQn = 30, /*!< TIM4 global Interrupt */
I2C1_EV_IRQn = 31, /*!< I2C1 Event Interrupt */
I2C1_ER_IRQn = 32, /*!< I2C1 Error Interrupt */
I2C2_EV_IRQn = 33, /*!< I2C2 Event Interrupt */
I2C2_ER_IRQn = 34, /*!< I2C2 Error Interrupt */
SPI1_IRQn = 35, /*!< SPI1 global Interrupt */
SPI2_IRQn = 36, /*!< SPI2 global Interrupt */
USART1_IRQn = 37, /*!< USART1 global Interrupt */
USART2_IRQn = 38, /*!< USART2 global Interrupt */
USART3_IRQn = 39, /*!< USART3 global Interrupt */
EXTI15_10_IRQn = 40, /*!< External Line[15:10] Interrupts */
RTC_Alarm_IRQn = 41, /*!< RTC Alarm (A and B) through EXTI Line Interrupt */
OTG_FS_WKUP_IRQn = 42, /*!< USB OTG FS Wakeup through EXTI line interrupt */
TIM8_BRK_TIM12_IRQn = 43, /*!< TIM8 Break Interrupt and TIM12 global interrupt */
TIM8_UP_TIM13_IRQn = 44, /*!< TIM8 Update Interrupt and TIM13 global interrupt */
TIM8_TRG_COM_TIM14_IRQn = 45, /*!< TIM8 Trigger and Commutation Interrupt and TIM14 global interrupt */
TIM8_CC_IRQn = 46, /*!< TIM8 Capture Compare Interrupt */
DMA1_Stream7_IRQn = 47, /*!< DMA1 Stream7 Interrupt */
FSMC_IRQn = 48, /*!< FSMC global Interrupt */
SDIO_IRQn = 49, /*!< SDIO global Interrupt */
TIM5_IRQn = 50, /*!< TIM5 global Interrupt */
SPI3_IRQn = 51, /*!< SPI3 global Interrupt */
UART4_IRQn = 52, /*!< UART4 global Interrupt */
UART5_IRQn = 53, /*!< UART5 global Interrupt */
TIM6_DAC_IRQn = 54, /*!< TIM6 global and DAC1&2 underrun error interrupts */
TIM7_IRQn = 55, /*!< TIM7 global interrupt */
DMA2_Stream0_IRQn = 56, /*!< DMA2 Stream 0 global Interrupt */
DMA2_Stream1_IRQn = 57, /*!< DMA2 Stream 1 global Interrupt */
DMA2_Stream2_IRQn = 58, /*!< DMA2 Stream 2 global Interrupt */
DMA2_Stream3_IRQn = 59, /*!< DMA2 Stream 3 global Interrupt */
DMA2_Stream4_IRQn = 60, /*!< DMA2 Stream 4 global Interrupt */
ETH_IRQn = 61, /*!< Ethernet global Interrupt */
ETH_WKUP_IRQn = 62, /*!< Ethernet Wakeup through EXTI line Interrupt */
CAN2_TX_IRQn = 63, /*!< CAN2 TX Interrupt */
CAN2_RX0_IRQn = 64, /*!< CAN2 RX0 Interrupt */
CAN2_RX1_IRQn = 65, /*!< CAN2 RX1 Interrupt */
CAN2_SCE_IRQn = 66, /*!< CAN2 SCE Interrupt */
OTG_FS_IRQn = 67, /*!< USB OTG FS global Interrupt */
DMA2_Stream5_IRQn = 68, /*!< DMA2 Stream 5 global interrupt */
DMA2_Stream6_IRQn = 69, /*!< DMA2 Stream 6 global interrupt */
DMA2_Stream7_IRQn = 70, /*!< DMA2 Stream 7 global interrupt */
USART6_IRQn = 71, /*!< USART6 global interrupt */
I2C3_EV_IRQn = 72, /*!< I2C3 event interrupt */
I2C3_ER_IRQn = 73, /*!< I2C3 error interrupt */
OTG_HS_EP1_OUT_IRQn = 74, /*!< USB OTG HS End Point 1 Out global interrupt */
OTG_HS_EP1_IN_IRQn = 75, /*!< USB OTG HS End Point 1 In global interrupt */
OTG_HS_WKUP_IRQn = 76, /*!< USB OTG HS Wakeup through EXTI interrupt */
OTG_HS_IRQn = 77, /*!< USB OTG HS global interrupt */
DCMI_IRQn = 78, /*!< DCMI global interrupt */
CRYP_IRQn = 79, /*!< CRYP crypto global interrupt */
HASH_RNG_IRQn = 80, /*!< Hash and Rng global interrupt */
FPU_IRQn = 81 /*!< FPU global interrupt
中断号是由MCU厂商定义的，用户不能修改。
中断优先级
正如人们在做事情的时候，会把事情的重要性进行划分，重要的事情先做，不重要的事情最后做。中断也是如此，STM32F4可以设置中断的优先级，优先级高的中断代表很重要，必须马上处理，优先级低的中断就代表没那么重要，可以晚点处理。
STM32F4X NVIC控制器
NVIC控制器简介
NVIC控制器是STM32F4X用来管理MCU中的外设中断的控制器，NVIC控制器可管理200多个中断，但是STM32F4只使用了其中的82个，所以STM32F4X对NVIC控制器做了些处理。
NVIC寄存器
在core_cm4.h中可以看到NVIC的寄存器位
typedef struct
{
__IO uint32_t ISER[8]; /*!< Offset: 0x000 (R/W) Interrupt Set Enable Register */
uint32_t RESERVED0[24];
__IO uint32_t ICER[8]; /*!< Offset: 0x080 (R/W) Interrupt Clear Enable Register */
uint32_t RSERVED1[24];
__IO uint32_t ISPR[8]; /*!< Offset: 0x100 (R/W) Interrupt Set Pending Register */
uint32_t RESERVED2[24];
__IO uint32_t ICPR[8]; /*!< Offset: 0x180 (R/W) Interrupt Clear Pending Register */
uint32_t RESERVED3[24];
__IO uint32_t IABR[8]; /*!< Offset: 0x200 (R/W) Interrupt Active bit Register */
uint32_t RESERVED4[56];
__IO uint8_t IP[240]; /*!< Offset: 0x300 (R/W) Interrupt Priority Register (8Bit wide) */
uint32_t RESERVED5[644];
__O uint32_t STIR; /*!< Offset: 0xE00 ( /W) Software Trigger Interrupt Register */
} NVIC_Type;
ISER:中断使能寄存器，总共有8个32位的寄存器，每一个位控制一个中断，总共可以控制256个中断。但是STM32F4X总共有82个外设中断，所以只用到了前3个寄存器。往该寄存器的相应位写1，则代表该位的中断被使能。
ICER:中断除能寄存器，该寄存器与ISER寄存器相反，往该寄存器的相应位写1，则代表该位的中断被除能。
ISPR:中断挂起寄存器，往该寄存器的相应位写1，则代表该位的中断被挂起。
ICPR:中断解挂起寄存器，往该寄存器的相应位写1，则代表该位的中断被解挂。
IABR:中断激活寄存器，当某个中断被执行时，该寄存器的对应位会被置1，可以读取该寄存器知道哪些中断被执行。
IP:中断优先级寄存器，通过设置该寄存器可以设置外设中断的优先级。
优先级分组
STM32F4X支持中断优先级分组，主要是由SCB->AIRCR这个寄存器实现分组功能。STM32F4X优先级总共可以分成5组。由SCB->AIRCR的bit8~bit10决定。具体的分组如下
| 分组 | AIRCR[8:10] | 结果 |
|---|---|---|
| 0 | 111 | 0位抢占优先级 4位响应优先级 |
| 1 | 110 | 1位抢占优先级 3位响应优先级 |
| 2 | 101 | 2位抢占优先级 2位响应优先级 |
| 3 | 100 | 3位抢占优先级 1位响应优先级 |
| 4 | 011 | 4位抢占优先级 0位响应优先级 |
STM32F4X的优先级规则如下:
- 抢占优先级高的中断可以打断抢占优先级低的中断
- 抢占优先级相同的，响应优先级高的中断不能打断响应优先级低的中断
- 抢占优先级相同的，如果两个中断同时发生，响应优先级高的中断先执行
- 抢占优先级和响应优先级相同的，哪个中断先发生就先执行。
STM32F4X中断配置
STM32F4X的中断配置有以下两个步骤
- 先配置优先级分组
- 配置相应外设的中断
优先级分组设置
设置优先级分组只需调用以下函数即可
#define NVIC_PriorityGroup_0 ((uint32_t)0x700) /*!< 0 bits for pre-emption priority
4 bits for subpriority */
#define NVIC_PriorityGroup_1 ((uint32_t)0x600) /*!< 1 bits for pre-emption priority
3 bits for subpriority */
#define NVIC_PriorityGroup_2 ((uint32_t)0x500) /*!< 2 bits for pre-emption priority
2 bits for subpriority */
#define NVIC_PriorityGroup_3 ((uint32_t)0x400) /*!< 3 bits for pre-emption priority
1 bits for subpriority */
#define NVIC_PriorityGroup_4 ((uint32_t)0x300) /*!< 4 bits for pre-emption priority
0 bits for subpriority */
/*
NVIC_PriorityGroup:对应的优先级分组
*/
void NVIC_PriorityGroupConfig(uint32_t NVIC_PriorityGroup)
该函数只需在初始化时设置一次即可。
配置外设中断
typedef struct
{
uint8_t NVIC_IRQChannel; // 中断号
uint8_t NVIC_IRQChannelPreemptionPriority; // 抢占优先级
uint8_t NVIC_IRQChannelSubPriority; // 响应优先级
FunctionalState NVIC_IRQChannelCmd; // 是否使能
} NVIC_InitTypeDef;
/*
NVIC_InitStruct:中断结构体
*/
void NVIC_Init(NVIC_InitTypeDef* NVIC_InitStruct)
比如现在需要配置串口接收中断，代码如下
NVIC_InitTypeDef NVIC_InitStruct;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); // 设置优先级分组为2，即2位抢占优先级和2位响应优先级
NVIC_InitStruct.NVIC_IRQChannel = USART1_IRQn; // USART1 中断编号
NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 1; // 抢占优先级为1
NVIC_InitStruct.NVIC_IRQChannelSubPriority = 1; // 响应优先级为1
NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE; // 使能中断
NVIC_Init(&NVIC_InitStruct); // 初始化中断
void USART1_IRQHandler(void) // 中断处理函数
{
// 业务代码
}
