单片机入门学习十一 STM32单片机学习八外部中断

妖狐艹你老母 2022-06-01 04:06 439阅读 0赞

[单片机入门学习九 STM32单片机学习六 延时函数、端口复用和重映射、中断][STM32_] 中 记录了内部中断NVIC，本篇将记录一下外部中断EXIT。

### 1、概述 ###

STM32的每个IO都可以作为**外部中断输入**。  
STM32的中断控制器支持**19个外部中断/事件请求**：

*  线0~15：对应外部IO口的输入中断。
 *  线16：连接到PVD输出。
 *  线17：连接到RTC闹钟事件。
 *  线18：连接到USB唤醒事件。
    
    #### 1）引脚与中断线对应关系 ####
    
    STM32F103有112个IO，但是中断线只有16个，中断线按如下方式与IO对应：我们知道STM32F103有7组IO，即GPIOA、GPIOB、…、GPIOG，每一组有16个引脚，如GPIOA0、GPIOA1、…、GPIOA15，因此STM32F103是按引脚分类为16组对应到16个中断线上，如下图：  
    ![中断线][SouthEast]  
    即：GPIOx.0映射到EXTI0、GPIOx.1映射到EXTI1、…、GPIOx.15映射到EXTI15。

#### 2）外部中断服务函数 ####

STM32的IO外部中断函数只有6个，如下：

EXPORT EXTI0_IRQHandler           
    EXPORT EXTI1_IRQHandler
    EXPORT EXTI2_IRQHandler           
    EXPORT EXTI3_IRQHandler           
    EXPORT EXTI4_IRQHandler           
    EXPORT EXTI9_5_IRQHandler         
    EXPORT EXTI15_10_IRQHandler

中断线0~4每个中断线对应一个中断函数，中断线5~9共用中断函数EXTI9\_5\_IRQHandler，中断线10~15共用中断函数EXTI15\_10\_IRQHandler。  
中断函数使用示例如下：

void EXTI3_IRQHandler(void){
        if(EXTI_GetITStatus(EXIT_Line3)!=RESET){
       //判断某个线上的中断是否发生
            ...
            EXTI_ClearITPendingBit(EXTI_Line3);//清除LINE上的中断标志位
        }
    }

#### 3）外部中断编写步骤 ####

①初始化IO口为输入。  
GPIO\_Init();  
② 开启IO口复用时钟。  
RCC\_APB2PeriphClockCmd(RCC\_APB2Periph\_AFIO,ENABLE);  
②设置IO口与中断线的映射关系。  
void GPIO\_EXTILineConfig();  
③初始化线上中断，设置触发条件等。  
EXTI\_Init();  
④配置中断分组（NVIC），并使能中断。  
NVIC\_Init();  
⑤编写中断服务函数。  
EXTIx\_IRQHandler();  
⑥清除中断标志位  
EXTI\_ClearITPendingBit();

#### 4）有关外部中断的相关变量定义 ####

`stm32f10x_exti.h`

typedef enum
    {
      EXTI_Mode_Interrupt = 0x00,
      EXTI_Mode_Event = 0x04
    }EXTIMode_TypeDef;
    
    #define IS_EXTI_MODE(MODE) (((MODE) == EXTI_Mode_Interrupt) || ((MODE) == EXTI_Mode_Event))
    
    typedef enum
    {
      EXTI_Trigger_Rising = 0x08,
      EXTI_Trigger_Falling = 0x0C,  
      EXTI_Trigger_Rising_Falling = 0x10
    }EXTITrigger_TypeDef;
    
    #define IS_EXTI_TRIGGER(TRIGGER) (((TRIGGER) == EXTI_Trigger_Rising) || \
                                      ((TRIGGER) == EXTI_Trigger_Falling) || \
                                      ((TRIGGER) == EXTI_Trigger_Rising_Falling))
    
    typedef struct
    {
      uint32_t EXTI_Line;               /*!< Specifies the EXTI lines to be enabled or disabled. This parameter can be any combination of @ref EXTI_Lines */
    
      EXTIMode_TypeDef EXTI_Mode;       /*!< Specifies the mode for the EXTI lines. This parameter can be a value of @ref EXTIMode_TypeDef */
    
      EXTITrigger_TypeDef EXTI_Trigger; /*!< Specifies the trigger signal active edge for the EXTI lines. This parameter can be a value of @ref EXTIMode_TypeDef */
    
      FunctionalState EXTI_LineCmd;     /*!< Specifies the new state of the selected EXTI lines. This parameter can be set either to ENABLE or DISABLE */ 
    }EXTI_InitTypeDef;
    
    #define EXTI_Line0 ((uint32_t)0x00001) /*!< External interrupt line 0 */
    #define EXTI_Line1 ((uint32_t)0x00002) /*!< External interrupt line 1 */
    #define EXTI_Line2 ((uint32_t)0x00004) /*!< External interrupt line 2 */
    #define EXTI_Line3 ((uint32_t)0x00008) /*!< External interrupt line 3 */
    #define EXTI_Line4 ((uint32_t)0x00010) /*!< External interrupt line 4 */
    #define EXTI_Line5 ((uint32_t)0x00020) /*!< External interrupt line 5 */
    #define EXTI_Line6 ((uint32_t)0x00040) /*!< External interrupt line 6 */
    #define EXTI_Line7 ((uint32_t)0x00080) /*!< External interrupt line 7 */
    #define EXTI_Line8 ((uint32_t)0x00100) /*!< External interrupt line 8 */
    #define EXTI_Line9 ((uint32_t)0x00200) /*!< External interrupt line 9 */
    #define EXTI_Line10 ((uint32_t)0x00400) /*!< External interrupt line 10 */
    #define EXTI_Line11 ((uint32_t)0x00800) /*!< External interrupt line 11 */
    #define EXTI_Line12 ((uint32_t)0x01000) /*!< External interrupt line 12 */
    #define EXTI_Line13 ((uint32_t)0x02000) /*!< External interrupt line 13 */
    #define EXTI_Line14 ((uint32_t)0x04000) /*!< External interrupt line 14 */
    #define EXTI_Line15 ((uint32_t)0x08000) /*!< External interrupt line 15 */
    #define EXTI_Line16 ((uint32_t)0x10000) /*!< External interrupt line 16 Connected to the PVD Output */
    #define EXTI_Line17 ((uint32_t)0x20000) /*!< External interrupt line 17 Connected to the RTC Alarm event */
    #define EXTI_Line18 ((uint32_t)0x40000) /*!< External interrupt line 18 Connected to the USB Device/USB OTG FS
                                                       Wakeup from suspend event */                                    
    #define EXTI_Line19 ((uint32_t)0x80000) /*!< External interrupt line 19 Connected to the Ethernet Wakeup event */
    
    #define IS_EXTI_LINE(LINE) ((((LINE) & (uint32_t)0xFFF00000) == 0x00) && ((LINE) != (uint16_t)0x00))
    #define IS_GET_EXTI_LINE(LINE) (((LINE) == EXTI_Line0) || ((LINE) == EXTI_Line1) || \
                                ((LINE) == EXTI_Line2) || ((LINE) == EXTI_Line3) || \
                                ((LINE) == EXTI_Line4) || ((LINE) == EXTI_Line5) || \
                                ((LINE) == EXTI_Line6) || ((LINE) == EXTI_Line7) || \
                                ((LINE) == EXTI_Line8) || ((LINE) == EXTI_Line9) || \
                                ((LINE) == EXTI_Line10) || ((LINE) == EXTI_Line11) || \
                                ((LINE) == EXTI_Line12) || ((LINE) == EXTI_Line13) || \
                                ((LINE) == EXTI_Line14) || ((LINE) == EXTI_Line15) || \
                                ((LINE) == EXTI_Line16) || ((LINE) == EXTI_Line17) || \
                                ((LINE) == EXTI_Line18) || ((LINE) == EXTI_Line19))
    
    void EXTI_DeInit(void);
    void EXTI_Init(EXTI_InitTypeDef* EXTI_InitStruct);
    void EXTI_StructInit(EXTI_InitTypeDef* EXTI_InitStruct);
    void EXTI_GenerateSWInterrupt(uint32_t EXTI_Line);
    FlagStatus EXTI_GetFlagStatus(uint32_t EXTI_Line);
    void EXTI_ClearFlag(uint32_t EXTI_Line);
    ITStatus EXTI_GetITStatus(uint32_t EXTI_Line);
    void EXTI_ClearITPendingBit(uint32_t EXTI_Line);

### 2、外部中断示例代码 ###

本示例代码实现的功能是按按键1 板子上的的两个LED灯的 交替亮，硬件连接图如下：  
![连接][SouthEast 1]

从上图中我们知道PE2接KEY3、PE3接KEY2、PE3接KEY1、PE5接LED1、PB5接LED0

代码如下：

staitc bool isLed0Light=true;
    
    void Base_Init(void)
    {
    
        EXTI_InitTypeDef EXTI_InitStructure;
        NVIC_InitTypeDef NVIC_InitStructure;
        GPIO_InitTypeDef GPIO_InitStructure;
    
        // 按键端口初始化
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE,ENABLE);//使能PORTA,PORTE时钟
    
        GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_3;//KEY3
        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; //设置成上拉输入
        GPIO_Init(GPIOE, &GPIO_InitStructure);//初始化GPIOE3
    
        //LED初始化 
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_GPIOE, ENABLE);   //使能PB,PE端口时钟
    
        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;                //LED0-->PB.5 端口配置
        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;         //推挽输出
        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;        //IO口速度为50MHz
        GPIO_Init(GPIOB, &GPIO_InitStructure);                   //根据设定参数初始化GPIOB.5
        GPIO_SetBits(GPIOB,GPIO_Pin_5);                      //PB.5 输出高
    
        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;                //LED1-->PE.5 端口配置, 推挽输出
        GPIO_Init(GPIOE, &GPIO_InitStructure);                   //推挽输出 ，IO口速度为50MHz
        GPIO_SetBits(GPIOE,GPIO_Pin_5);                          //PE.5 输出高 
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE); //使能复用功能时钟
    
        //GPIOE.3 中断线以及中断初始化配置 下降沿触发 //KEY1
        GPIO_EXTILineConfig(GPIO_PortSourceGPIOE,GPIO_PinSource3);
        EXTI_InitStructure.EXTI_Line=EXTI_Line3;
        EXTI_Init(&EXTI_InitStructure);     //根据EXTI_InitStruct中指定的参数初始化外设EXTI寄存器
    
        EXTI_InitStructure.EXTI_Line=EXTI_Line3;    //KEY1
        EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt; 
        EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
        EXTI_InitStructure.EXTI_LineCmd = ENABLE;
        EXTI_Init(&EXTI_InitStructure);     //根据EXTI_InitStruct中指定的参数初始化外设EXTI寄存器
    
        NVIC_InitStructure.NVIC_IRQChannel = EXTI3_IRQn;            //使能按键KEY1所在的外部中断通道
        NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02;    //抢占优先级2 
        NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x01;                   //子优先级1 
        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 
    }
    
    //外部中断3服务程序
    void EXTI3_IRQHandler(void)
    {
        delay_ms(10);//消抖
        uint8_t KEY1 = GPIO_ReadInputDataBit(GPIOE,GPIO_Pin_3)//读取按键1
        if(KEY1==0)  //按键KEY1，因为由按键电路图知当键按下时单片机接到的是低电平，所以KEY1==0表示按下KEY1
        {
            if(isLed0Light){
                isLed0Light = !isLed0Light;
                GPIO_SetBits(GPIOE, GPIO_Pin_5);//LED1点亮
                GPIO_ResetBits(GPIOB, GPIO_Pin_5);//LED0熄灭
            }else{
                GPIO_SetBits(GPIOB, GPIO_Pin_5);//LED0点亮
                GPIO_ResetBits(GPIOE, GPIO_Pin_5);//LED1熄灭
            }
        }        
        EXTI_ClearITPendingBit(EXTI_Line3);  //清除LINE3上的中断标志位 
    }

[STM32_]: http://blog.csdn.net/fengshuiyue/article/details/79084776
[SouthEast]: /images/20220601/991b27ab1da043eda9b8145896b0b3e6.png
[SouthEast 1]: /images/20220601/cb4c78b3739f4f68a6631e5d9474b99e.png