Study Materials

Li Xiang stm32 video tutorial 49 episodes  http://pan.baidu.com/s/1kTyt03P   STM32 interrupts (upper, middle and lower) external interrupts (registers, library functions)
STM32 function description (Chinese).pdf     http://download.csdn.net/detail/leytton/7630851
Interrupt management function.pdf   http://wenku.baidu.com/view/b90e5b82360cba1aa811dad3.html

17 - EXTI line 16 connected to PVD output

18 - EXTI line 17 connected to the RTC alarm event

19 - EXTI line 18 connected to USB wake-up event

 

Note: From the above figure, we can see that the pins connected to EXTI0 are PA0, PB0, PC0, PD0, PE0, PF0, PG0, and other external interrupts EXTI1——

EXTI15 is similar. So when using, try to configure the required external interrupts on different EXTIx.

      For example, if three external interrupts are needed, we can configure them to PA0, PB4, and PG3. At this time, each interrupt has its own interrupt handler.

     If PA0, PB0, and PC1 are configured, PA0 and PB0 will share an interrupt program segment.

     It can be designed like this.

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Configuration usage:

1. Initialize the corresponding GPIO pins

2. Configure external interrupt sources and connect interrupt sources to GPIO

3. Write the interrupt handler for the corresponding interrupt source

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code

• Initialize the corresponding GPIO pins

GPIO_InitTypeDef GPIO_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);           
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;   
GPIO_Init(GPIOE, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8|GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;   
GPIO_Init(GPIOB, &GPIO_InitStructure);

Note: GPIO multiplexing function must be turned on, as shown in the red part

• Configure external interrupt sources and connect interrupt sources to GPIO

GPIO_EXTILineConfig(GPIO_PortSourceGPIOE, GPIO_PinSource0);
GPIO_EXTILineConfig(GPIO_PortSourceGPIOE, GPIO_PinSource1);
GPIO_EXTILineConfig(GPIO_PortSourceGPIOB, GPIO_PinSource8);
GPIO_EXTILineConfig(GPIO_PortSourceGPIOB, GPIO_PinSource9);

 
EXTI_InitStructure.EXTI_Line = EXTI_Line0|EXTI_Line1|EXTI_Line8|EXTI_Line9;
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);

• Write the interrupt handler for the corresponding interrupt source

void EXTI0_IRQHandler(void)
{
  if(Sys_Status > MIN_STATUS)
  {
    Sys_Status --;
  }
  EXTI_ClearITPendingBit(EXTI_Line0);
}

void EXTI1_IRQHandler(void)
{
  PEout(2) = ~PEout(2);
  EXTI_ClearITPendingBit(EXTI_Line1);
}

#define Exti_From_Pin8 0x00000100
#define Exti_From_Pin9 0x00000200

void EXTI9_5_IRQHandler(void)
{

  u32 Temp = 0x00; 

  PEout(2) = ~PEout(2);
  Temp = EXTI->PR;       //取读是那个引脚的中断
  switch(Temp)
  {
    case Exti_From_Pin8:
      EXTI_ClearITPendingBit(EXTI_Line8);
      break;
    case Exti_From_Pin9:
      if(Sys_Status < MAX_STATUS)
      {
        Sys_Status ++;
      }
      EXTI_ClearITPendingBit(EXTI_Line9);
      break;
    default:break;
  }
}

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Interrupt handler description: Since external interrupts EXTI5-EXTI9 share an interrupt (EXTI10-EXTI15 are similar),

Differentiating different interrupt sources requires corresponding judgment. As shown in EXTI9_5_IRQHandler above, the judgment is made by reading the EXTI->PR register.

The source of the interrupt.