1. 配置PA4，PA5为外部中断
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1. void EXTI_Config(void)
   
2. {
   
3.   EXTI_InitTypeDef   EXTI_InitStructure;
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4.   GPIO_InitTypeDef   GPIO_InitStructure;
   
5.   NVIC_InitTypeDef   NVIC_InitStructure;
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6. 
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7.   /* Enable GPIOA clock */
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8.   RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA|RCC_AHBPeriph_GPIOF, ENABLE);
   
9. 
   
10.   /* Configure PA4&PA5 pin as input floating */
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11.   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4|GPIO_Pin_5;
    
12.   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
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13.   GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    
14.   GPIO_Init(GPIOA, &GPIO_InitStructure);
    
15. 
    
16.   /* Enable SYSCFG clock */
    
17.   RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
    
18. 
    
19.   /* Connect EXTI4 Line to PA4 pin */
    
20.   SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource4|EXTI_PinSource5);
    
21. 
    
22.   /* Configure EXTI4&EXTI5 line */
    
23.   EXTI_InitStructure.EXTI_Line = EXTI_Line4|EXTI_Line5;
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24.   EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
    
25.   EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
    
26.   EXTI_InitStructure.EXTI_LineCmd = ENABLE;
    
27.   EXTI_Init(&EXTI_InitStructure);
    
28. 
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29.   /* Enable and set EXTI4&EXTI5 Interrupt */
    
30.   NVIC_InitStructure.NVIC_IRQChannel = EXTI4_15_IRQn;
    
31.   NVIC_InitStructure.NVIC_IRQChannelPriority = 0x00;
    
32.   NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    
33.   NVIC_Init(&NVIC_InitStructure);
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34. }

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% Q8 B$ g; Y4 r2 r8 x2， 外部触发中断函数
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1. void EXTI4_15_IRQHandler(void)
   
2. {
   
3.   if(EXTI_GetITStatus(EXTI_Line4) != RESET)
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4.   {
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5.     /* Clear the EXTI line 0 pending bit */
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6.     EXTI_ClearITPendingBit(EXTI_Line4);
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7.         if(PauseFlag == 0)
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8.         {
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9.             ExtiCnt++;
   
10. 
    
11.         }
    
12.   }
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13.   if(EXTI_GetITStatus(EXTI_Line5) != RESET)
    
14.   {
    
15.     /* Clear the EXTI line 0 pending bit */
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16.     EXTI_ClearITPendingBit(EXTI_Line5);
    
17.         if(PauseFlag == 0)
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18.         {
    
19.             ExtiCnt++;
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20. 
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21.         }
    
22.   }
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23. }

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