STM32笔记之 EXIT（外部中断）

写在前面：
本文章旨在总结备份、方便以后查询，由于是个人总结，如有不对，欢迎指正；另外，内容大部分来自网络、书籍、和各类手册，如若侵权请告知，马上删帖致歉。

 

目录

一、EXIT控制原理

二、外部中断的 I/O映像

三、中断服务

四、配置流程（代码解析）

五、中断函数处理

---

 

在上一篇 STM32笔记之 GPIO引脚中，有用到 EXIT外部中断作为 Key输入触发，所以本篇来诠释一下 EXIT外部中断的功能

 

一、EXIT控制原理

 

二、外部中断的 I/O映像

从上面图中我们可以发现，每一组端口都对应着相应的 “ 线 ”，先称之为线吧！

其中，还有 4条 EXIT线是特殊的，看上图

 

三、中断服务

#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 */

以上的 EXIT线的宏都可以在 stm32f10x_exti.h文件中找到

 

上图的中断函数表可以在参考手册中找到，下面用一个表格来整合官方划分的中断函数

I/O 口外部中断函数	中断线
EXTI0_IRQHandler	EXIT0 Line
EXTI1_IRQHandler	EXIT1 Line
EXTI2_IRQHandler	EXIT2 Line
EXTI3_IRQHandler	EXIT3 Line
EXTI4_IRQHandler	EXIT4 Line
EXTI9_5_IRQHandler	EXIT5 - 9 Line
EXTI15_10_IRQHandler	EXIT10 - 15 Line

因为在官方提供的 stm32f10x_it.c文件中，所列出来的中断函数只有下图的部分重要的中断，其他外设中断函数需要我们自己添加

外设的中断需要我们自己添加，官方在 stm32f10x_it.c文件的底部也有注释说明，看下图

 

四、配置流程（代码解析）

在上一篇配置 Key输入检测的代码中，如下进行配置

其中，上图框选的部分是跟 EXIT是相关联的，你可能会问 NVIC是干嘛的，别急，下篇再解释；

在分析 EXTI函数之前先来了解一下两个组定义

/** 
  * @brief  EXTI Trigger enumeration  
  */

typedef enum
{
  EXTI_Trigger_Rising = 0x08,          // 上升沿触发
  EXTI_Trigger_Falling = 0x0C,         // 下降沿触发
  EXTI_Trigger_Rising_Falling = 0x10   // 上下沿触发
}EXTITrigger_TypeDef;

/** 
  * @brief  EXTI Init Structure definition  
  */

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;

 

1、GPIO_EXTILineConfig() 函数

/* Connect EXTI1 Line to PB.01 pin */
GPIO_EXTILineConfig(GPIO_PortSourceGPIOB, GPIO_PinSource1);    // 将 EXTI1线连接到 PB.01引脚

↓↓ 函数实现 ↓↓

/**
  * @brief  Selects the GPIO pin used as EXTI Line.
  * @param  GPIO_PortSource: selects the GPIO port to be used as source for EXTI lines.
  *   This parameter can be GPIO_PortSourceGPIOx where x can be (A..G).
  * @param  GPIO_PinSource: specifies the EXTI line to be configured.
  *   This parameter can be GPIO_PinSourcex where x can be (0..15).
  * @retval None
  */
void GPIO_EXTILineConfig(uint8_t GPIO_PortSource, uint8_t GPIO_PinSource)
{
  uint32_t tmp = 0x00;
  /* Check the parameters */
  assert_param(IS_GPIO_EXTI_PORT_SOURCE(GPIO_PortSource));
  assert_param(IS_GPIO_PIN_SOURCE(GPIO_PinSource));
  
  tmp = ((uint32_t)0x0F) << (0x04 * (GPIO_PinSource & (uint8_t)0x03));
  AFIO->EXTICR[GPIO_PinSource >> 0x02] &= ~tmp;
  AFIO->EXTICR[GPIO_PinSource >> 0x02] |= (((uint32_t)GPIO_PortSource) << (0x04 * (GPIO_PinSource & (uint8_t)0x03)));
}

2、EXTI_Init()函数

/* Configure EXTI1 line */
EXTI_InitStructure.EXTI_Line = EXTI_Line1;              // 选着 EXIT1线
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;     // 配置为输入模式
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling; // 下降沿触发
EXTI_InitStructure.EXTI_LineCmd = ENABLE;               // 使能 EXIT1线
EXTI_Init(&EXTI_InitStructure);

↓↓ 函数实现 ↓↓

/**
  * @brief  Initializes the EXTI peripheral according to the specified
  *         parameters in the EXTI_InitStruct.
  * @param  EXTI_InitStruct: pointer to a EXTI_InitTypeDef structure
  *         that contains the configuration information for the EXTI peripheral.
  * @retval None
  */
void EXTI_Init(EXTI_InitTypeDef* EXTI_InitStruct)
{
  uint32_t tmp = 0;

  /* Check the parameters */
  assert_param(IS_EXTI_MODE(EXTI_InitStruct->EXTI_Mode));
  assert_param(IS_EXTI_TRIGGER(EXTI_InitStruct->EXTI_Trigger));
  assert_param(IS_EXTI_LINE(EXTI_InitStruct->EXTI_Line));  
  assert_param(IS_FUNCTIONAL_STATE(EXTI_InitStruct->EXTI_LineCmd));

  tmp = (uint32_t)EXTI_BASE;
     
  if (EXTI_InitStruct->EXTI_LineCmd != DISABLE)
  {
    /* Clear EXTI line configuration */
    EXTI->IMR &= ~EXTI_InitStruct->EXTI_Line;
    EXTI->EMR &= ~EXTI_InitStruct->EXTI_Line;
    
    tmp += EXTI_InitStruct->EXTI_Mode;

    *(__IO uint32_t *) tmp |= EXTI_InitStruct->EXTI_Line;

    /* Clear Rising Falling edge configuration */
    EXTI->RTSR &= ~EXTI_InitStruct->EXTI_Line;
    EXTI->FTSR &= ~EXTI_InitStruct->EXTI_Line;
    
    /* Select the trigger for the selected external interrupts */
    if (EXTI_InitStruct->EXTI_Trigger == EXTI_Trigger_Rising_Falling)
    {
      /* Rising Falling edge */
      EXTI->RTSR |= EXTI_InitStruct->EXTI_Line;
      EXTI->FTSR |= EXTI_InitStruct->EXTI_Line;
    }
    else
    {
      tmp = (uint32_t)EXTI_BASE;
      tmp += EXTI_InitStruct->EXTI_Trigger;

      *(__IO uint32_t *) tmp |= EXTI_InitStruct->EXTI_Line;
    }
  }
  else
  {
    tmp += EXTI_InitStruct->EXTI_Mode;

    /* Disable the selected external lines */
    *(__IO uint32_t *) tmp &= ~EXTI_InitStruct->EXTI_Line;
  }
}

3、EXTI_GenerateSWInterrupt()函数

/* Generate software interrupt: simulate a falling edge applied on EXTI1 line */
EXTI_GenerateSWInterrupt(EXTI_Line1);    // 生成软件中断:模拟应用于 EXTI1线路的下降沿

↓↓ 函数实现 ↓↓

/**
  * @brief  Generates a Software interrupt.
  * @param  EXTI_Line: specifies the EXTI lines to be enabled or disabled.
  *   This parameter can be any combination of EXTI_Linex where x can be (0..19).
  * @retval None
  */
void EXTI_GenerateSWInterrupt(uint32_t EXTI_Line)
{
  /* Check the parameters */
  assert_param(IS_EXTI_LINE(EXTI_Line));
  
  EXTI->SWIER |= EXTI_Line;
}

 

五、中断函数处理

/**
  * @brief  This function handles External line 1 interrupt request.
  * @param  None
  * @retval None
  */
void EXTI1_IRQHandler(void)
{
	if(EXTI_GetITStatus(EXTI_Line1) != RESET)      // 检测 EXIT线路是否触发
	{
		/* Clear the  EXTI line 1 pending bit */
		EXTI_ClearITPendingBit(EXTI_Line1);        // 清除 EXIT线路触发标志
	}
}