1: EXTI (external interrupt) description

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       The external interrupt/event controller consists of 19 edge detectors that generate event/interrupt requests. Each input line can be independently configured

Input type (pulse or pending) and corresponding trigger event (rising edge or falling edge or both edges). Each input line can be independently

The Pending Register holds the interrupt request for the Status Line.

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The 19 interrupts are as follows:

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:

Initialize the corresponding GPIO pins

Configure external interrupt sources and connect interrupt sources to GPIO

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; //Read the interrupt pin

  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.

Hardware: Using PA11 pin

It should be clear that the PxN pins share the external interrupt line EXTIN and the external interrupt vector EXTIN_IRQn and the interrupt service routine entry EXTIN_IRQHandler, but it should be noted that [9...5] share EXTI9_5_IRQn and EXTI9_5_IRQHandler, and [15...10] share EXTI15_10_IRQn and EXTI15_10_IRQHandler

2: Use of Stm32 external interrupt EXTI

Basic process:

1. Set the clock

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);  

Note that you need to turn on the AFIO clock

2. Configure GPIO

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;  

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;  

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;  

GPIO_Init(GPIOA, &GPIO_InitStructure);  

Use floating input method

3. Connect the GPIO pin to the external interrupt line

GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource11);  

Quite important

4. Configure EXTI

EXTI_InitStructure.EXTI_Line = EXTI_Line11;  

EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;  

EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;  

EXTI_InitStructure.EXTI_LineCmd = ENABLE;  

EXTI_Init(&EXTI_InitStructure);  

Including triggering methods, etc.

6. Configure NVIC

NVIC_InitTypeDef NVIC_InitStructure;      

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);  

NVIC_InitStructure.NVIC_IRQChannel = EXTI15_10_IRQn; //PPP external interrupt line  

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;  

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;  

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;  

NVIC_Init(&NVIC_InitStructure);  

7. Write interrupt service routine

void EXTI15_10_IRQHandler(void)  

{  

    if (EXTI_GetITStatus(EXTI_Line11) != RESET)  

    {  

        EXTI_ClearITPendingBit(EXTI_Line11);//Clear flag  

        ...  

    }  

}