AT89C51 MCU external interrupt

The C51 microcontroller external interrupt calls P3_2 and P3_3 ports.

There are two interrupt modes: level mode and pulse mode.

The interrupt request has 0 and 1. The interrupt is always enabled when EA=1.

IE0: external interrupt request 0 flag;

IT0: External interrupt 0 trigger mode setting bit, IT0=1 falling edge trigger, IT0=0 low level trigger;

IE1: External interrupt request 1 flag;

IT1: External interrupt 1 trigger mode setting bit, IT1=1 falling edge trigger, IT1=0 low level trigger;

Writing of external interrupt 0 interrupt service program:

void function name () interrupt 0

{

}

Writing of external interrupt 1 interrupt service program:

void function name () interrupt 2

{

}

Refer to the experimental program (the main program is the P1 port output marquee program), write an interrupt subroutine so that when external interrupt 0 occurs and it is triggered at a low level, all LED lights are on. After the interrupt ends, the LED continues to flash in the last state.

#include

#include

sbit P3_2=P3^2;

void delay(unsigned char i);

void main()

{

unsigned char ii;

P1=0xFE;

P3_2=1;

EA=1;

EX0=1;

IT0=0;

while(1)

{

P1=0xFE;

for(ii=0;ii<8;ii++)

{

P1=_crol_(P1,1);

delay(200);

}

}

}

void delay(unsigned char i) //delay function, unsigned character type variable i is the formal parameter

{

unsigned char j,k; //define unsigned character type variables j and k

for(k=0;k for(j=0;j<255;j++);

}

void int_0() interrupt 0

{

P1=0x00;

}

Refer to the experimental program (the main program is the P1 port output marquee program). When external interrupt 1 occurs and it is triggered by a low level, the LED flashes 5 times. After the interrupt ends, the LED continues to flash as in the last state.

#include

#include

sbit P3_3=P3^3;

void delay(unsigned char i);

void main()

{

unsigned char ii;

P1=0xFE;

P3_2=1;

EA=1;

EX1=1;

IT1=0;

while(1)

{

P1=0xFE;

for(ii=0;ii<8;ii++)

{

P1=_crol_(P1,1);

delay(200);

}

}

}

void delay(unsigned char i) //delay function, unsigned character type variable i is the formal parameter

{

unsigned char j,k; //define unsigned character type variables j and k

for(k=0;k for(j=0;j<255;j++);

}

void int_1() interrupt 2

{

unsigned char a;

for(a=0;a<5;a++)

{

P1=0x00;

delay(200);

P1=0xff;

delay(200);

}

}

Refer to the experimental program (the main program is the P1 port output marquee program), and write an interrupt subroutine so that when external interrupt 0 occurs and is triggered by a low level, all LED lights are on. After the interrupt ends, the LED continues to flash as in the last state with a marquee; when external interrupt 1 occurs and is triggered by a low level, the LED lights flash 5 times. After the interrupt ends, the LED continues to flash as in the last state with a marquee.

#include

#include

sbit P3_2=P3^2;

sbit P3_3=P3^3;

void delay(unsigned char i);

void main()

{

unsigned char ii;

P1=0xFE;

P3_2=1;

EA=1;

EX0=1;

IT0=0;

EX1=1;

IT1=0;

while(1)

{

P1=0xFE;

for(ii=0;ii<8;ii++)

{

P1=_crol_(P1,1);

delay(200);

}

}

}

void delay(unsigned char i) //delay function, unsigned character type variable i is the formal parameter

{

unsigned char j,k; //define unsigned character type variables j and k

for(k=0;k for(j=0;j<255;j++);

}

void int_0() interrupt 0 //0 trigger

{

P1=0x00;

}

void int_1() interrupt 2 //1 trigger

{

unsigned char a;

for(a=0;a<5;a++)

{

P1=0x00;

delay(200);

P1=0xff;

delay(200);

}

}