1. 配置PA4，PA5为外部中断

1. void EXTI_Config(void)
   
2. {
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3.   EXTI_InitTypeDef   EXTI_InitStructure;
   
4.   GPIO_InitTypeDef   GPIO_InitStructure;
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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. 
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10.   /* Configure PA4&PA5 pin as input floating */
    
11.   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4|GPIO_Pin_5;
    
12.   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
    
13.   GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
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14.   GPIO_Init(GPIOA, &GPIO_InitStructure);
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15. 
    
16.   /* Enable SYSCFG clock */
    
17.   RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
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18. 
    
19.   /* Connect EXTI4 Line to PA4 pin */
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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;
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26.   EXTI_InitStructure.EXTI_LineCmd = ENABLE;
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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;
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31.   NVIC_InitStructure.NVIC_IRQChannelPriority = 0x00;
    
32.   NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    
33.   NVIC_Init(&NVIC_InitStructure);
    
34. }

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1. void EXTI4_15_IRQHandler(void)
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2. {
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3.   if(EXTI_GetITStatus(EXTI_Line4) != RESET)
   
4.   {
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5.     /* Clear the EXTI line 0 pending bit */
   
6.     EXTI_ClearITPendingBit(EXTI_Line4);
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7.         if(PauseFlag == 0)
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8.         {
   
9.             ExtiCnt++;
   
10. 
    
11.         }
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12.   }
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13.   if(EXTI_GetITStatus(EXTI_Line5) != RESET)
    
14.   {
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15.     /* Clear the EXTI line 0 pending bit */
    
16.     EXTI_ClearITPendingBit(EXTI_Line5);
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17.         if(PauseFlag == 0)
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18.         {
    
19.             ExtiCnt++;
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20. 
    
21.         }
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22.   }
    
23. }

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