51 microcontroller external interrupt experiment

Earlier, we talked about the input and output functions of the 51 microcontroller. Today we will talk about something different, external interrupt testing.

First of all, we have to talk about the role of interruptions in dealing with internal and external random events and responding to emergencies. While the CPU is executing the program, if an external emergency event occurs, the CPU stops its work to handle the emergency event. After processing, it returns to the place where it was originally interrupted and continues working. It's like receiving a phone call while eating, going out to answer the phone and then sitting back at the table to eat. Stopping what you were doing and doing other things in the middle is an interruption.

The interrupt function of the 51 microcontroller is relatively simple. You only need to configure the corresponding registers to complete the initialization.

In this article, the external interrupt is tested using button P3.2 because its port has the second function of external interrupt.

Before configuring the interrupt structure of the 51 microcontroller, you need to look at the internal structure diagram. You can see that there are IE, IP, TCON and other registers to control the interrupt function.

Different registers have different functions. Each register has 8-bit configuration bits, which are responsible for different functions. Among them, the most important external interrupts are the IE and TCON registers. For details, you can read the 51 microcontroller data manual, which will provide detailed introduction.

The detailed code is as follows:

#include

sbit ExternalInterruptPin = P3^2; // External interrupt pin definition

void ExternalInterrupt_Init() {

    IT0 = 1; // Set external interrupt 0 to falling edge trigger mode

    EX0 = 1; // Enable external interrupt 0

    EA = 1; // Global interrupt enable

}

void ExternalInterrupt_Service() interrupt 0 {

    // Process logic in the interrupt service routine

    // ...

}

void main() {

    ExternalInterrupt_Init();

    while (1) {

        //Other logic in the main loop

        // ...

    }

}

Among them, void ExternalInterrupt_Service () interrupt 0

One line is the 51 microcontroller interrupt service function, which has been designed by the semiconductor manufacturer. We only need to use it according to regulations, unless we are working on the kernel, we will not consider the design issues.

There are many other interrupt functions as shown below. Just choose different functions according to different ports and functions:

Note: The so-called falling edge is the edge that changes from high level to low level, that is, the time when the transition occurs.