ASM software interrupt

[Ryan]

First of all I want to say hello to all the member here

I am trying to learn more ASM on my own cause I can’t get any good help from professors in my school.

I have one problem I need to use interrupt in my newest program but I don’t know how to use it cause no-one show us how does interrupt looks like in source code… We have been only learning theory…

Pls tell me how xactly we use interrrupts

[Amit Joshi]

 interrupts are used when we need to perform a special task during regular task. the full attention of controller is removed from regular task to an important task until this important task is performed.

 

for example a controller is busy in blinking led on a port0. at Pin 1.0 a buzzer is connected. and a switch is connected to int0 pin. ur task is to on the buzzer when u want. if u use polling u have to monitor P3.2 continuously during led blinking process and this will consume ur 24 clock cycle in each poll. this is not efficient programming .  if u use interrupt concept there is no need to monitor the pin P3.2.

example code-

            ORG 0000H

            LJMP MAIN;

 

            ORG 0003H               // int0 isr address   

            SETB P1.0;                 // buzzer on when interrupt occur

            RETI;                          // return interrupt 

 

              ORG 0030H

MAIN:  SETB TCON.0;        // int0 an edge trigger interrupt

             MOV IE,#81H;        // enable harwre interrupt int0

HERE:   CPL P0;                   // led bilinking

             ACALL delay;

             SJMP HERE;

 

Delay:                                 // generate a delay subroutine 

 

END

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