【51单片机快速入门指南】3.1：配置外部中断触发方式和中断优先级

普中51-单核-A2

STC89C52

Keil uVision V5.29.0.0

PK51 Prof.Developers Kit Version:9.60.0.0

源码

stdint.h见【51单片机快速入门指南】1：基础知识和工程创建

中断知识见【51单片机快速入门指南】3：中断系统

将外部中断0和外部中断1均配置为下降沿触发，但外部中断1的优先级最高，外部中断0的优先级最低。

EXTI.c

#include

#include 'intrins.h'

#include 'stdint.h'

#include 'EXTI.h'

//定义LED管脚

sbit D1 = P2^0;

sbit D2 = P2^1;

//定义独立按键控制脚

sbit K3 = P3^2;

sbit K4 = P3^3;

void Delay20ms() //@11.0592MHz

{

unsigned char i, j;

i = 36;

j = 217;

do

{

while (--j);

} while (--i);

}

//P3.2

void EXTI0_Callback() interrupt 0 //外部中断0中断函数

{

Delay20ms();

if(K3 == 0)

{

D1 = !D1;

while(K3 == 0);

}

}

//P3.3

void EXTI1_Callback() interrupt 2 //外部中断1中断函数

{

Delay20ms();

if(K4 == 0)

{

D2 = !D2;

while(K4 == 0);

}

}

#if USE_EXTI2_EXTI3

//P4.3

void EXTI2_Callback() interrupt 6 //外部中断2中断函数

{

}

//P4.2

void EXTI3_Callback() interrupt 7 //外部中断3中断函数

{

}

#endif

#if EXTI_USE_STC

sfr IPH = 0xb7;

#endif

void EXTI0_Init(uint8_t EXTI_Type, uint8_t Priority)

{

#if EXTI_USE_STC

IPH &= ~1;

IPH |= (2 & Priority) >> 1;

#endif

PX0  = (1 & Priority); //设置中断优先级

IT0  = EXTI_Type; //触发方式

EX0  = 1; //打开INT0的中断允许

EA   = 1; //打开总中断

}

void EXTI0_Switch(uint8_t Status)

{

EX0  = Status;

}

void EXTI1_Init(uint8_t EXTI_Type, uint8_t Priority)

{

#if EXTI_USE_STC

IPH &= ~4;

IPH |= (2 & Priority) << 1;

#endif

PX1  = (1 & Priority); //设置中断优先级

IT1 = EXTI_Type; //触发方式

EX1 = 1; //打开INT1的中断允许

EA = 1; //打开总中断

}

void EXTI1_Switch(uint8_t Status)

{

EX1  = Status;

}

#if USE_EXTI2_EXTI3

sfr XICON = 0xc0;

sbit PX2 = XICON^3;

sbit EX2 = XICON^2;

sbit IE2 = XICON^1;

sbit IT2 = XICON^0;

sbit PX3 = XICON^7;

sbit EX3 = XICON^6;

sbit IE3 = XICON^5;

sbit IT3 = XICON^4;

void EXTI2_Init(uint8_t EXTI_Type, uint8_t Priority)

{

#if EXTI_USE_STC

IPH &= ~0x40;

IPH |= (2 & Priority) << 5;

#endif

PX2  = (1 & Priority); //设置中断优先级

IT2 = EXTI_Type; //触发方式

EX2 = 1; //打开INT1的中断允许

EA = 1; //打开总中断

}

void EXTI2_Switch(uint8_t Status)

{

EX2  = Status;

}

void EXTI3_Init(uint8_t EXTI_Type, uint8_t Priority)

{

#if EXTI_USE_STC

IPH &= ~0x80;

IPH |= (2 & Priority) << 6;

#endif

PX3  = (1 & Priority); //设置中断优先级

IT3 = EXTI_Type; //触发方式

EX3 = 1; //打开INT1的中断允许

EA = 1; //打开总中断

}

void EXTI3_Switch(uint8_t Status)

{

EX3  = Status;

}

#endif

EXTI.h

#ifndef EXTI_H_

#define EXTI_H_

#include 'stdint.h'

//使用外部中断2（P4.3）和外部中断3（P4.2） 貌似只有LQFP44封装的芯片才有，普通的DIP40芯片没有

#define USE_EXTI2_EXTI3 1

//使用STC单片机的4级优先级

#define EXTI_USE_STC 1

#define EXTI_LOW_LEVEL 0

#define EXTI_FALLING 1

#if EXTI_USE_STC

//STC单片机的4级优先级

#define STC_EXTI_Priority_Lowest 0

#define STC_EXTI_Priority_Lower 1

#define STC_EXTI_Priority_Higher 2

#define STC_EXTI_Priority_Highest 3

#endif

//传统51单片机的2级优先级

#define EXTI_Priority_Low 0

#define EXTI_Priority_High 1

void EXTI0_Init(uint8_t EXTI_Type, uint8_t Priority);

void EXTI0_Switch(uint8_t Status);

void EXTI1_Init(uint8_t EXTI_Type, uint8_t Priority);

void EXTI1_Switch(uint8_t Status);

#if USE_EXTI2_EXTI3

void EXTI2_Init(uint8_t EXTI_Type, uint8_t Priority);

void EXTI2_Switch(uint8_t Status);

void EXTI3_Init(uint8_t EXTI_Type, uint8_t Priority);

void EXTI3_Switch(uint8_t Status);

#endif

#endif

main.c

#include

#include 'intrins.h'

#include 'stdint.h'

#include 'EXTI.h'

void main(void)

{

EXTI0_Init(EXTI_FALLING, STC_EXTI_Priority_Lowest);

EXTI1_Init(EXTI_FALLING, STC_EXTI_Priority_Highest);

while(1)

{

}

}

实验现象

按下K3，D0翻转；按下K4，D1翻转。

当按住K3时(处理外部中断0时)，仍可响应外部中断1；

当按住K4时(处理外部中断1时)，不能响应外部中断0。