Each year, globally, approximately one new processor is manufactured per person. That’s more than six billion new processors each year, fewer than two percent of which are the Pentiums and PowerPCs at the heart of new personal computers. You may wonder whether there are really that many computers surrounding us. But we bet that within five minutes you can probably spot dozens of products in your own home that contain processors: televisions, stereos, MP3 players, coffee makers, alarm clocks, VCRs, DVD players, microwaves, dishwashers, remote controls, bread machines, digital watches, and so on. And those are just the personal possessions—many more such devices are used at work. The fact that every one of those products contains not only a processor, but also software, is the impetus for this book.

One of the hardest things about this subject is knowing when to stop writing. Each embedded system is unique, and we have therefore learned that there is an exception to every rule. Nevertheless, we have tried to boil the subject down to its essence and present the things that programmers definitely need to know about embedded systems.

This is a book about programming embedded systems in C. As such, it assumes that the reader already has some programming experience and is at least familiar with the syntax of the C language. It also helps if you have some familiarity with basic data structures, such as linked lists. The book does not assume that you have a great deal of knowledge about computer hardware, but it does expect that you are willing to learn a little bit about hardware along the way. This is, after all, a part of the job of an embedded programmer.

While writing this book, we had two types of readers in mind. The first reader is a beginner—much as we were once. He has a background in computer science or engineering and a few years of programming experience. The beginner is interested in writing embedded software for a living but is not sure just how to get started. After reading the first several chapters, he will be able to put his programming skills to work developing simple embedded programs. The rest of the book will act as a reference for the more advanced topics encountered in the coming months and years of his career.

The second reader is already an embedded systems programmer. She is familiar with embedded hardware and knows how to write software for it but is looking for a reference book that explains key topics. Perhaps the embedded systems programmer has experience only with assembly language programming and is relatively new to C. In that case, the book will teach her how to use the C language effectively in an embedded system, and the later chapters will provide advanced material on real-time operating systems, peripherals, and code optimizations.

Whether you fall into one of these categories or not, we hope this book provides the information you are looking for in a format that is friendly and easily accessible.

The book contains 14 chapters and 5 appendixes. The chapters can be divided quite nicely into two parts. The first part consists of Chapters 1 through 5 and is intended mainly for newcomers to embedded systems. These chapters should be read in their entirety and in the order that they appear. This will bring you up to speed quickly and introduce you to the basics of embedded software development. After completing Chapter 5, you will be ready to develop small pieces of embedded software on your own.

The second part of the book consists of Chapters 6 through 14 and discusses advanced topics that are of interest to inexperienced and experienced embedded programmers alike. These chapters are mostly self-contained and can be read in any order. In addition, Chapters 6 through 12 contain example programs that might be useful to you on a future embedded software project.

Throughout the book, we have tried to strike a balance between specific examples and general information. Whenever possible, we have eliminated minor details in the hope of making the book more readable. You will gain the most from the book if you view the examples, as we do, primarily as tools for understanding important concepts. Try not to get bogged down in the details of any one circuit board or chip. If you understand the general C programming concepts, you should be able to apply them to any embedded system you encounter.

To focus the book’s example code on specific concepts, we intentionally left it incomplete—for example, by eliminating certain include files and redundant variable declarations. For complete details about the code, refer to the full example source code on the book’s web site.

The following typographical conventions are used throughout the book:

Other conventions relate to gender and roles. With respect to gender, we have purposefully used both “he” and “she” throughout the book. With respect to roles, we have occasionally distinguished between the tasks of hardware engineers, embedded software engineers, and application programmers. But these titles refer only to roles played by individual engineers, and it should be noted that it can and often does happen that a single individual fills more than one of these roles on an embedded-project team.

This book includes many source code listing, and all but the most trivial snippets are available online. These examples are organized by chapter number and include build instructions (makefiles) to help you recreate each of the executables. The complete archive is available at http://examples.oreilly.com/embsys2.

This book is here to help you get your job done. In general, you may use the code in this book in your programs and documentation. You do not need to contact us for permission unless you’re reproducing a significant portion of the code. For example, writing a program that uses several chunks of code from this book does not require permission. Selling or distributing a CD-ROM of examples from O’Reilly books does require permission. Answering a question by citing this book and quoting example code does not require permission. Incorporating a significant amount of example code from this book into your product’s documentation does require permission.

We appreciate, but do not require, attribution. An attribution usually includes the title, author, publisher, and ISBN. For example: “Programming Embedded Systems with C and GNU Development Tools, Second Edition, by Michael Barr and Anthony Massa. Copyright 2007 O’Reilly Media, Inc., 978-0-596-00983-0.”

If you feel your use of code examples falls outside fair use or the permission given above, feel free to contact us at [email protected].

Please address comments and questions concerning this book to the publisher:

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