ID: Technology Makes Dreams GreaterCompiled by: Li XiaoyaoAs the saying goes, the beginning is always the hardest. When you first start, do you feel completely lost, unable to find your way through a sea of new terms while searching online? Even going to the library to read books feels directionless? With ARM, Linux, and U-Boot all swirling in your head, where do you even begin?Follow me as I share my journey of becoming an embedded engineer!In simple terms, the learning path goes from basic ARM knowledge to bare-metal programming, from uCOSII to Linux, from basic Linux commands to shell programming, from U-Boot to file systems, and finally to Linux driver development. The progression is from simple to complex, from basic to advanced.01Phase One: Fundamentals of Embedded Hardware and Bare-Metal Programming1. Knowledge Points:(1) Basics of ARM processors, operating modes, registers, interrupts and exceptions, addressing modes, assembly instruction set(2) Familiarity with the ADS integrated development environment in preparation for bare-metal programming(3) Bare-metal programming: LED, serial port, LCD, touchscreen, NAND flash, I2C, IIS, DMA, etc.2. Process and Purpose:This phase focuses on familiarizing oneself with embedded hardware to lay the groundwork for future Linux driver development. Since the primary architecture for embedded systems is ARM, the learning is centered around ARM. First, learn the basics, then practice on a development board. The main resources used in this phase include:(1) “ARM Embedded Basics Tutorial” – This book covers the fundamentals of ARM. Although it discusses ARM7, the basic instruction set and architecture are consistent across ARM.(2) “Complete Manual for Embedded Linux Application Development” – This book mainly covers the S3C2410 interface module, which is essential for understanding hardware during bare-metal experiments.3. Time Required:Approximately two months.02Phase Two: Linux Basics and Shell Programming1. Knowledge Points:(1) Basic knowledge of Linux(2) Installation and usage of Linux(3) Common Linux commands(4) Using vi(5) Basic shell programming2. Process and Purpose:This phase focuses on becoming familiar with Linux, learning to install it, understanding basic concepts, and performing simple operations. Initially, it is better to install Linux on a virtual machine, and for the development board, it is recommended to use Fedora 9, following the accompanying instructions step by step to practice various commands.The main resource for this phase is “Bird Brother’s Linux Cookbook: Basic Learning Edition”. This book has an electronic version and does not need to be read in its entirety; focus on the sections that describe basic Linux knowledge and commands. It is not necessary to memorize all commands; they can be looked up as needed later. The main goal of this phase is to gain an overall understanding of Linux, at least to know some basic concepts and perform basic operations.3. Time Required:Approximately one month.03Phase Three: Basic Development of Linux Applications1. Knowledge Points:(1) Basics of GCC, GDB, Make(2) File and time programming(3) Multi-process and multi-thread program design(4) Inter-process communication2. Process and Purpose:This phase focuses on understanding the writing and debugging of Linux applications, which are also foundational concepts, primarily aimed at becoming familiar with Linux. Understanding application-related concepts lays the groundwork for future development. The main resource for this phase is “Standard Tutorial for Embedded Linux Application Development”, which provides detailed explanations on writing applications in Linux and is not too difficult. The classic book “Advanced Programming in the UNIX Environment” is more in-depth and may be challenging at first, but starting with simpler materials is advisable. After learning application programming, it is not necessary to work exclusively in applications; however, these are essential skills for anyone in the embedded Linux field.3. Time Required:Approximately one month.04Phase Four: Learning the uCOSII Operating System1. Knowledge Points:(1) Concepts and fundamentals of embedded real-time operating systems(2) Reading the source code of the uCOSII operating system(3) Porting uCOSII(4) Application programming with the uCOSII operating system2. Process and Purpose:This phase focuses on understanding the basics of embedded real-time operating systems, as uCOSII is open-source and allows for code study. It provides an intuitive understanding of task scheduling and resource management in operating systems. Reading its source code can enhance programming skills and standardize coding habits. Although a ported version of uCOSII is provided, performing the porting process oneself leads to a deeper understanding.This operating system is relatively simple, so writing applications is crucial for understanding the system. The main resource for this phase is the book “Embedded Real-Time Operating System uCOS-II” translated by Shao Beibei, which provides detailed analysis of the operating system’s source code. After thoroughly understanding this book, one will have an in-depth understanding of uCOSII. The main goals of this phase are to learn about operating system concepts such as task scheduling, concurrency, and race conditions, as well as to improve programming skills. Reading the source code of an operating system is much more beneficial than reading a thousand books on operating principles.3. Time Required:Approximately one month.05Phase Five: Learning Bootloaders1. Knowledge Points:(1) Basics of bootloaders(2) Basics and commands of U-Boot(3) Porting U-Boot2. Process and Purpose:The bootloader is an essential part of a Linux embedded system. This phase focuses on understanding the role of the bootloader and the general bootloader—U-Boot. Initially, learn to use various commands in U-Boot, then analyze the boot process of U-Boot, the Makefile, and the kernel loading process. Follow others’ steps to port the kernel step by step, and after becoming familiar with the entire U-Boot process, complete the U-Boot porting independently and add personal modifications. The main reference materials for this phase are the U-Boot porting reference manual included on the CD and various online articles. I find that there is a wealth of online resources for U-Boot porting.3. Time Required:Approximately one month.06Phase Six: Learning File Systems1. Knowledge Points:(1) Types and functions of Linux file systems(2) Familiarity with the use of BusyBox and the Linux system startup process(3) Building your own root file system2. Process and Purpose:The file system is also an indispensable part of a Linux embedded system. This phase focuses on understanding the role and fundamentals of the root file system and building your own root file system. The main resource for this phase is “Building Embedded Linux Systems”, which details all elements of embedded Linux, including file systems. Here, the focus is primarily on the file system section. I also referred to various online articles. First, familiarize yourself with basic Linux file systems, then learn to use BusyBox and the Linux startup process, and finally follow others’ steps to build your own file system.3. Time Required:Approximately half a month.07Phase Seven: Embedded Graphical User Interface (GUI)1. Knowledge Points:(1) Types and characteristics of embedded graphical user interfaces(2) Basics of MiniGUI(3) Porting MiniGUI and programming2. Process and Purpose:As an upper-level system component, the embedded graphical user interface (GUI) is also important to understand. I only studied MiniGUI because QT requires knowledge of C++, which I have not learned. The main goal of this phase is to familiarize myself with the development process of embedded graphical interfaces, as I do not plan to work in application development.Simply porting MiniGUI to the board and running a hello program is sufficient. There is no need to delve deeper. Through porting MiniGUI, I gained a new understanding of software and function libraries running on Linux, as well as the principles of program execution and compilers.3. Time Required:Approximately half a month.08Phase Eight: Basic Knowledge of Linux Device Drivers1. Knowledge Points:(1) Read “Linux Device Drivers” and cover all chapters except for network drivers, tty drivers, and block drivers.(2) Experiment with all examples in the book, carefully analyze the results, and understand related knowledge points.(3) Even for examples, ensure programming habits are consistent and documentation is standardized.2. Process and Purpose:The purpose of this phase is to lay the foundation for Linux drivers. “Linux Device Drivers” (3rd edition), commonly referred to as LDD3, is the classic book on Linux drivers that must be read multiple times. The first reading may be difficult to grasp, as it can be obscure and hard to understand. However, after several readings, it becomes clearer. After reading the book, experiment with the examples provided.3. Time Required:Approximately two months.09Phase Nine: Practical Linux Driver Development1. Knowledge Points:(1) Understand the registration and implementation of miscellaneous character devices through LED drivers, and master the IO operation process of MINI2440.(2) Master basic interrupt implementation methods through button driver programs.(3) Master PWM driver programming.(4) Understand the implementation of the input device model through touchscreen driver programs.(5) Master the design of ADC driver programs.(6) Master the design of watchdog and RTC driver programs.(7) Analyze the implementation of the platform device model through LCD driver programs.2. Process and Purpose:This phase focuses on mastering the implementation of simple driver programs and analyzing differences from LDD3, as well as examining various Linux subsystems. Through this phase, one can gain a deeper understanding of Linux driver programming and improve the ability to read large amounts of code. The main work in this phase involves reading code, experimenting, and learning through observation.3. Time Required:Approximately one month.10Phase Ten: In-Depth Understanding of the Linux Kernel and USB Subsystem ResearchHaving completed the first nine phases, I feel that I have entered the realm of embedded Linux. It is time to plan for the tenth phase, which will help determine my future direction. Since USB is a standard interface in embedded systems, learning about USB is highly competitive. Those working on drivers should have a certain understanding of the kernel, so “Understanding the Linux Kernel” is essential.This phase mainly involves studying the USB protocol, reading all the code of the Linux USB subsystem, deepening the understanding of USB through code reading, and then familiarizing oneself with various USB class protocols, as well as writing and porting USB drivers. USB is the direction I have chosen because I believe that focusing on one area is crucial; trying to do everything will lead to failure in all. Therefore, I have decided to pursue work related to USB in embedded systems. This phase of learning is ongoing, and I am currently exploring the vast code of the Linux USB subsystem.–END-| Article compiled for the dissemination of related technologies, copyright belongs to the original author |If there is any infringement, please contact for removal |
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