MCU interrupt problem

Introduction: Isn't the interrupt of 51 MCU just jumping to another place when something happens in the middle, and returning after execution? Why do we need to use interrupts specifically? Can't we just jump to the instruction directly?

First of all, to understand the interrupt, we must first talk about the pins of the microcontroller P3 port; P30 to P35 are the input pins of the interrupt. Including serial ports, timers (counters), external interrupts, etc. The characteristics of these interrupts are that when the interrupt conditions are met, the corresponding interrupt program will be executed. Note that there is an important difference between the execution of the interrupt program and the subroutine of the assembly language: (most textbooks do not mention this point) The subroutine must have a call statement such as ACALL to call it before it can be executed; but the interrupt is not! It is automatically executed after the interrupt condition is met. For example: the timer counts full; the external interrupt pin is triggered at a low level; the serial port receives data..., at this time the program automatically jumps to the interrupt entry: 03H, 0BH, .... 23H. After entering the interrupt entry, it is generally necessary to jump and then jump to the corresponding interrupt subroutine (unless your interrupt program is very short and will not enter other interrupts). Take C language as an example, in C51, the interrupt function does not need to be called by the main function main(), and is automatically executed (provided that the condition that triggers the interrupt occurs).

Isn't interruption just jumping to another place when something happens in the middle and returning after execution?

The "what happens in the middle" here refers to the interrupt that is triggered. According to the type of interrupt that is triggered, the program automatically jumps to the entry program (for example, if external interrupt 0 is triggered, it jumps to 03H, and if serial port interrupt is triggered, it jumps to 23H. These entry addresses are generally arranged with jump instructions)

Why do we need to use interrupts specifically? Can't we just jump to the instruction directly?

The microcontroller works in this way of interruption! For example, when the microcontroller is processing data, an external device sends a signal to start. This is an external interrupt signal. After receiving it, the microcontroller enters the corresponding interrupt program to start the device, or monitor the device, etc. Without interruption, the function of the microcontroller is greatly reduced. Does it mean that one is a known conditional jump and the other is unknown, so the interruption is used. This is the meaning, but it is not accurate. The interrupt is caused by an external signal, or the clock timing is reached, or the serial data is received. In short, the generation of the interrupt is not determined by the code in the program.