神舟IV學習筆記（八）外部中斷EXIT

外部中斷有點像51單片機的中斷INT一樣，都能夠設置為上升沿、下降沿和雙邊沿觸發(fā)；不同之處在于STM32的大多數GPIO口都能設置為外部中斷輸入功能，這樣帶來的好處有：在PCB設計和需求大量外部中斷功能很有幫助。STM32F107VCT一共有5組GPIO，每組又有16個引腳。這里提供復用的方式提供了16個中斷源。PA0、PB0、PC0、PD0、PE0都是共有相同的中斷源EXIT0。

開發(fā)板上的按鍵對應關系為：KEY1—PC4；KEY2—PB10；KEY3—PC13；KEY4—PA0。外接上拉電阻，在設置GPIO的狀態(tài)的時候，可以設置為輸入上拉模式。然后采用GPIO_EXTILineConfig庫函數將GPIO設置為EXTI模式。

/* Selects KEY1-PC.04 as EXTI Line 4 */

GPIO_EXTILineConfig(GPIO_PortSourceGPIOC, GPIO_PinSource4);

第三步是設置EXTI的模式，最后是編寫相應的中斷函數。

需要注意的是中斷向量表中EXTI5到EXTI9是復用在一起的，名稱為EXTI9_5；

EXTI10到EXTI15是復用在一起的，名稱為EXTI15_10；

這部分主程序為：

void NVIC_Configuration(void)

{

NVIC_InitTypeDef NVIC_InitStructure;

/* Configure the Priority Group to 2 bits */

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);

/* Enable the EXTI Interrupt */

NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

NVIC_InitStructure.NVIC_IRQChannel = EXTI4_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;

NVIC_Init(&NVIC_InitStructure);

NVIC_InitStructure.NVIC_IRQChannel = EXTI15_10_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;

NVIC_Init(&NVIC_InitStructure);

}

int main(void)

{

/* Setup STM32 system (clock, PLL and Flash configuration) */

SystemInit();

/* Add your application code here

*/

LED_Configuration();

KEY_Configuration();//按鍵時鐘和端口配置

EXIT_Configuration();//外部中斷配置

NVIC_Configuration();

/* Infinite loop */

while (1)

{

}

}

void EXTI0_IRQHandler(void)/* Key 4 */

{

if(EXTI_GetITStatus(EXTI_Line0) != RESET)

{

LED_ALL_OFF();

LED4_ON();

/* Clear the EXTI Line 0 */

EXTI_ClearITPendingBit(EXTI_Line0);

}

}

/*******************************************************************************

* Function Name: EXTI4_IRQHandler

* Description: This function handles External interrupt Line 4 request.

* Input: None

* Output: None

* Return: None

*******************************************************************************/

void EXTI4_IRQHandler(void) /* Key 1 */

{

if(EXTI_GetITStatus(EXTI_Line4) != RESET)

{

LED_ALL_OFF();

LED1_ON();

/* Clear the EXTI Line 4 */

EXTI_ClearITPendingBit(EXTI_Line4);

}

}

/*******************************************************************************

* Function Name: EXTI15_10_IRQHandler

* Description: This function handles External lines 15 to 10 interrupt request.

* Input: None

* Output: None

* Return: None

*******************************************************************************/

void EXTI15_10_IRQHandler(void) /* Key 2 & 3 */

{

if(EXTI_GetITStatus(EXTI_Line10) != RESET)

{

LED_ALL_OFF();

LED2_ON();

/* Clear the EXTI Line 10 */

EXTI_ClearITPendingBit(EXTI_Line10);

}

if(EXTI_GetITStatus(EXTI_Line13) != RESET)

{

LED_ALL_OFF();

LED3_ON();

/* Clear the EXTI Line 13 */

EXTI_ClearITPendingBit(EXTI_Line13);

}

}