Understand the basic concepts of Embedded Linux

Embedded Linux is a Linux operating system that runs in embedded systems. It is open source and customizable and is widely used in various embedded devices. Understanding the basic concepts of Embedded Linux is very important for those engaged in embedded development. This article will start with the basic concepts and introduce the relevant knowledge of Embedded Linux with specific code examples.

Basic concepts of Embedded Linux

1. Kernel: The Linux kernel is the core part of Embedded Linux. It manages hardware resources, provides system call interfaces, and is responsible for scheduling and manage system resources. The hardware support and function implementation of embedded devices rely on the Linux kernel.
2. File system: The file system is an organizational structure for storing and managing files in embedded systems. Common Embedded Linux file systems include Ext2/Ext3/Ext4, JFFS2, UBIFS, etc. The choice of file system is related to the memory type and requirements of the embedded device.
3. Device driver: Device driver is an important part of realizing the interaction between hardware and software, including character device driver, block device driver, network driver, etc. Writing device drivers requires an in-depth understanding of the working principles and register operations of hardware devices.
4. User space tools: User space tools are programs that run in user space and are used to configure the system, monitor system performance, and perform application development, etc. Common user space tools include busybox, sysfsutils, top, etc.

Code Example for Embedded Linux

Next, we will demonstrate how to write and run applications in Embedded Linux through a simple LED control code example. We assume that an LED light is connected to the development board and the corresponding kernel module has been loaded.

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

#define LED_PATH "/sys/class/leds/led0/brightness"

int main() {
    int fd;
    char buf[2];

    fd = open(LED_PATH, O_WRONLY);
    if (fd < 0) {
        perror("Error opening LED file");
        exit(1);
    }

    //Control the LED light
    buf[0] = '1';
    write(fd, buf, 1);

    sleep(2); // delay 2 seconds

    //Control LED light off
    buf[0] = '0';
    write(fd, buf, 1);

    close(fd);

    return 0;
}

In this example, we open the LED control file /sys/class/leds/led0/brightness, and then write the character '1' to it to make the LED light up , and then write the character '0' after a delay of 2 seconds to turn off the LED light. Finally close the file descriptor and exit the program.

Summary

Through the introduction of this article, we have understood the basic concepts of Embedded Linux, including the kernel, file system, device driver, user space tools, etc., and combined with code examples to demonstrate how to use Embedded Linux The process of writing applications in Linux. In-depth study of embedded system development and understanding of the principles and applications of Embedded Linux will help us better utilize the Linux platform to develop various embedded devices.

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