【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

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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。