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);
}
}
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