STM32 Basic Experiment 4 (Key Interrupt)

Key interruption experiment, experiment 2 is key query

1. Experimental Principle

1. Use the buttons in query and interrupt mode 

For buttons, use query and interrupt modes. Query mode is to put a piece of code in a loop, for example, in the main function, you can query in real time and process it when you find a change, while interrupt mode uses hardware to query the change status and then respond. The difference between the two is that one needs to write the query software code by yourself, and the other is to configure the interrupt mode during initialization, and then directly write your processing code in the interrupt. 

2. Implementation steps 

① Initialize the IO port as input (in key.c!)

void KEY_Init(void) //IO initialization

{ 

    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA|RCC_APB2Periph_GPIOE,ENABLE); //Enable PORTA, PORTE clock

    GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_4|GPIO_Pin_3;//KEY0-KEY1

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; //Set to pull-up input

    GPIO_Init(GPIOE, &GPIO_InitStructure); //Initialize GPIOE4,3

    //Initialize WK_UP-->GPIOA.0 pull-down input

    GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_0;

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; //PA0 is set to input, pull-down by default     

    GPIO_Init(GPIOA, &GPIO_InitStructure); //Initialize GPIOA.0

}

② Turn on AFIO clock 

RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE); 

③Set the mapping relationship between IO port and interrupt line. 

void GPIO_EXTILineConfig(); 

④Initialize online interrupts, set trigger conditions, etc. 

EXIT_Init(); 

⑤Configure the interrupt group NVIC and enable interrupt. 

NVIC_Init(); 

⑥Write interrupt service function. 

EXTIx_IRQHandler(); 

⑦ Clear the interrupt flag 

EXTI_ClearITPendingBit();

2. Experimental Code

**exit.c**

#include "exti.h"

#include "led.h"

#include "key.h"

#include "delay.h"

#include "usart.h"

#include "beep.h"

void EXTIX_Init(void)

{

    EXTI_InitTypeDef EXTI_InitStructure;

    NVIC_InitTypeDef NVIC_InitStructure;

    KEY_Init(); //Key port initialization

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE); //Enable multiplexing function clock

   //GPIOE.3 interrupt line and interrupt initialization configuration falling edge trigger //KEY1

    GPIO_EXTILineConfig(GPIO_PortSourceGPIOE,GPIO_PinSource3);

    EXTI_InitStructure.EXTI_Line=EXTI_Line3;

    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt; 

    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;

    EXTI_Init(&EXTI_InitStructure); //Initialize the peripheral EXTI registers according to the parameters specified in EXTI_InitStruct

   //GPIOE.4 interrupt line and interrupt initialization configuration falling edge trigger //KEY0

    GPIO_EXTILineConfig(GPIO_PortSourceGPIOE,GPIO_PinSource4);

    EXTI_InitStructure.EXTI_Line=EXTI_Line4;

    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt; 

    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;

    EXTI_Init(&EXTI_InitStructure); //Initialize the peripheral EXTI registers according to the parameters specified in EXTI_InitStruct

   //GPIOA.0 interrupt line and interrupt initialization configuration rising edge trigger PA0 WK_UP

    GPIO_EXTILineConfig(GPIO_PortSourceGPIOA,GPIO_PinSource0); 

    EXTI_InitStructure.EXTI_Line=EXTI_Line0;

    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;

    EXTI_Init(&EXTI_InitStructure); //Initialize the peripheral EXTI registers according to the parameters specified in EXTI_InitStruct

    NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn; // Enable the external interrupt channel where the WK_UP button is located

    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02; //Preemption priority 2, 

    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x03; //Subpriority 3

    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //Enable external interrupt channel

    NVIC_Init(&NVIC_InitStructure); 

    NVIC_InitStructure.NVIC_IRQChannel = EXTI3_IRQn; // Enable the external interrupt channel where the key KEY1 is located

    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02; //Preemption priority 2 

    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x01; //Subpriority 1 

    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //Enable external interrupt channel

    NVIC_Init(&NVIC_InitStructure); //Initialize peripheral NVIC registers according to the parameters specified in NVIC_InitStruct

    NVIC_InitStructure.NVIC_IRQChannel = EXTI4_IRQn; // Enable the external interrupt channel where the key KEY0 is located

    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02; //Preemption priority 2 

    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x00; //Subpriority 0 

    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //Enable external interrupt channel

    NVIC_Init(&NVIC_InitStructure); //Initialize peripheral NVIC registers according to the parameters specified in NVIC_InitStruct

}

//External interrupt 0 service routine 

void EXTI0_IRQHandler(void)

{

    delay_ms(10); //debounce

    if(WK_UP==1) //WK_UP button

    {                

        BEEP=!BEEP; 

    }

    EXTI_ClearITPendingBit(EXTI_Line0); //Clear the interrupt flag on LINE0  

}

//External interrupt 3 service routine

void EXTI3_IRQHandler(void)

{

    delay_ms(10); //debounce

    if(KEY1==0) //key KEY1

    {                

        LED1=!LED1;

    }        

    EXTI_ClearITPendingBit(EXTI_Line3); //Clear the interrupt flag on LINE3  

}

void EXTI4_IRQHandler(void)

{

    delay_ms(10); //debounce

    if(KEY0==0) //key KEY0

    {

        LED0=!LED0;

        LED1=!LED1; 

    }        

    EXTI_ClearITPendingBit(EXTI_Line4); //Clear the interrupt flag on LINE4  

}