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stm32f401 EXTI
EXTI就是External interrupt/event controller, 外部事件和中断控制器, 包含21条边沿检测线. 每条线可以独立设置触发事件(上升沿, 下降沿或两者同时). 一个等待寄存器维护中断请求的状态. 当动作发生(例如按键按下)时, 如果电平状态由低变高, 会在输入线产生一个上升沿信号, 这个信号到达边沿检测电路后, 会被上升沿触发选择寄存器(EXTI_RTSR)检测并触发, 输出有效信号, 否则输出无效信号0. 反之如果电平由高变低, 则会被下降沿触发选择寄存器(EXTI_FTSR)检测触发. EXTI可以在外部连线上检测到比内部APB2时钟周期更短的脉冲. stm32f4系列最多有81个GPIO可以连接到16个外部中断线. IO口和中断线的映射是多对一的, 例如EXTI0, 可以对应PA0, PB0, PC0等, 实际用到某个I/O引脚时, 通过配置决定具体哪个引脚对应EXTI0. 在stm32f4xx_exti.h中定义了0 - 23的中断线 #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 OTG FS Wakeup from suspend event */ #define EXTI_Line19 ((uint32_t)0x80000) /*!< External interrupt line 19 Connected to the Ethernet Wakeup event */ #define EXTI_Line20 ((uint32_t)0x00100000) /*!< External interrupt line 20 Connected to the USB OTG HS (configured in FS) Wakeup event */ #define EXTI_Line21 ((uint32_t)0x00200000) /*!< External interrupt line 21 Connected to the RTC Tamper and Time Stamp events */ #define EXTI_Line22 ((uint32_t)0x00400000) /*!< External interrupt line 22 Connected to the RTC Wakeup event */ #define EXTI_Line23 ((uint32_t)0x00800000) /*!< External interrupt line 23 Connected to the LPTIM Wakeup event */ 在stm32f4xx.h中, 有这些中断的常量, 注意: Line虽然是各自独立的, 但是IRQn不是, Handler也不是 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 */ EXTI9_5_IRQn = 23, /*!< External Line[9:5] Interrupts */ EXTI15_10_IRQn = 40, /*!< External Line[15:10] Interrupts */ 可以看到, 对于EXTI0到EXTI4(Line0到Line4), 都是单独的常量, 而Line5到Line9, Line10到Line15都是合用的. 对应的, 有以下的中断处理方法, 通过这些方法将自己的中断逻辑关联到对应的中断事件上去 EXTI0_IRQHandler EXTI1_IRQHandler EXTI2_IRQHandler EXTI3_IRQHandler EXTI4_IRQHandler EXTI9_5_IRQHandler EXTI15_10_IRQHandler 初始化的步骤
static void EXTILine0_Config(void); static void EXTILine13_15_Config(void); /* Private functions ---------------------------------------------------------*/ /** * @brief Main program * @param None * @retval None */ int main(void) { /* Initialize LEDs mounted on EVAL board */ STM_EVAL_LEDInit(LED1); STM_EVAL_LEDInit(LED2); /* Configure EXTI Line0 (connected to PA0 pin) in interrupt mode */ EXTILine0_Config(); /* Configure EXTI Line13/15 (connected to PG13/15 pin) in interrupt mode according to EVAL used */ EXTILine13_15_Config(); /* Generate software interrupt: simulate a falling edge applied on EXTI0 line */ EXTI_GenerateSWInterrupt(EXTI_Line0); while (1) { } } /** * @brief Configures EXTI Line0 (connected to PA0 pin) in interrupt mode * @param None * @retval None */ static void EXTILine0_Config(void) { EXTI_InitTypeDef EXTI_InitStructure; GPIO_InitTypeDef GPIO_InitStructure; NVIC_InitTypeDef NVIC_InitStructure; /* Enable GPIOA clock */ RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); /* Enable SYSCFG clock */ RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE); /* Configure PA0 pin as input floating */ GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; GPIO_Init(GPIOA, &GPIO_InitStructure); /* Connect EXTI Line0 to PA0 pin */ SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource0); /* Configure EXTI Line0 */ EXTI_InitStructure.EXTI_Line = EXTI_Line0; EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt; EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising; EXTI_InitStructure.EXTI_LineCmd = ENABLE; EXTI_Init(&EXTI_InitStructure); /* Enable and set EXTI Line0 Interrupt to the lowest priority */ NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); } /** * @brief Configures EXTI Line15 (connected to PG15 pin) in interrupt mode * @param None * @retval None */ static void EXTILine13_15_Config(void) { EXTI_InitTypeDef EXTI_InitStructure; GPIO_InitTypeDef GPIO_InitStructure; NVIC_InitTypeDef NVIC_InitStructure; #ifdef USE_STM324x9I_EVAL /* Enable GPIOC clock */ RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE); #else /* Enable GPIOG clock */ RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOG, ENABLE); #endif /* USE_STM324x9I_EVAL */ /* Enable SYSCFG clock */ RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE); /* Configure PG15 pin as input floating */ GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; #ifdef USE_STM324x9I_EVAL GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13; GPIO_Init(GPIOC, &GPIO_InitStructure); #else GPIO_InitStructure.GPIO_Pin = GPIO_Pin_15; GPIO_Init(GPIOG, &GPIO_InitStructure); #endif /* USE_STM324x9I_EVAL */ /* Connect EXTI Line15 to PG15 pin */ #ifdef USE_STM324x9I_EVAL SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOC, EXTI_PinSource13); #else SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOG, EXTI_PinSource15); #endif /* USE_STM324x9I_EVAL */ /* Configure EXTI Line15 */ #ifdef USE_STM324x9I_EVAL EXTI_InitStructure.EXTI_Line = EXTI_Line13; #else EXTI_InitStructure.EXTI_Line = EXTI_Line15; #endif /* USE_STM324x9I_EVAL */ EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt; EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling; EXTI_InitStructure.EXTI_LineCmd = ENABLE; EXTI_Init(&EXTI_InitStructure); /* Enable and set EXTI15_10 Interrupt to the lowest priority */ NVIC_InitStructure.NVIC_IRQChannel = EXTI15_10_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); } 处理中断的例子 中断处理, 涉及的就是三步: 1)消抖(如果是按键触发), 2)确认中断源, 3)清除中断标志位 // 1 void EXTI4_IRQHandler( void ) { delay_ms( 10 ); /* 消抖 */ if ( GPIO_ReadInputDataBit( GPIOE, GPIO_Pin_4 ) == 0 ) { GPIO_ResetBits(GPIOF,GPIO_Pin_9);//输出低电平,灯亮 } /* 清除LINE4上的中断标志位 */ EXTI_ClearITPendingBit( EXTI_Line4 ); } // 2 void EXTI0_IRQHandler(void) { if(EXTI_GetITStatus(EXTI_Line0) != RESET) {} // 确保产生了EXTI0线中断 LED_TOGGLE; // LED灯状态切换 EXTI_ClearITPendingBit(EXTI_Line0);// 清除中断标志位 } } // 3 /* Set interrupt handlers */ /* Handle PB12 interrupt */ void EXTI15_10_IRQHandler(void) { /* Make sure that interrupt flag is set */ if (EXTI_GetITStatus(EXTI_Line12) != RESET) { /* Do your stuff when PB12 is changed */ /* Clear interrupt flag */ EXTI_ClearITPendingBit(EXTI_Line12); } } |
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