Real-Time Embedded Multithreading Using ThreadX and MIPS.pdf

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Preface

Embedded systems are ubiquitous. These systems are found in most consumer

electronics, automotive, government, military, communications, and medical equipment.

Most individuals in developed countries have many such systems and use them daily,

but relatively few people realize that these systems actually contain embedded computer

systems. Although the ﬁ eld of embedded systems is young, the use and importance of

these systems is increasing, and the ﬁ eld is rapidly growing and maturing.

This book is intended for persons who develop embedded systems, or for those who

would like to know more about the process of developing such systems. Although

embedded systems developers are typically software engineers or electrical engineers,

many people from other disciplines have made signiﬁ cant contributions to this ﬁ eld.

This book is speciﬁ cally targeted toward embedded applications that must be small, fast,

reliable, and deterministic. 1

This book is composed of 14 chapters that cover embedded and real-time concepts, the

MIPS ® processor, all the services provided by the ThreadX ® real-time operating system

(RTOS), solutions to classical problem areas, and a case study. I assume the reader has

a programming background in C or C

, so we won’t devote any time to programming

fundamentals. Depending on the background of the reader, the chapters of the book may

be read independently.

There are several excellent books written about embedded systems. However, most of these

books are written from a generalist point of view. This book is unique because it is based

on embedded systems development using a typical commercial RTOS, as well as a typical

microprocessor. This approach has the advantage of providing speciﬁ c knowledge and

techniques, rather than generic concepts that must be converted to your speciﬁ c system.

Thus, you can immediately apply the topics in this book to your development efforts.

Because an actual RTOS is used as the primary tool for embedded application

development, there is no discussion about the merits of building your own RTOS or

1 Such systems are sometimes called deeply embedded systems.

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xvi

Preface

forgoing an RTOS altogether. I believe that the relatively modest cost of a commercial

RTOS provides a number of signiﬁ cant advantages over attempts to “ build your own. ” For

example, most commercial RTOS companies have spent years reﬁ ning and optimizing

their systems. Their expertise and product support may play an important role in the

successful development of your system.

The RTOS chosen for use in this book is ThreadX 2 (version 5). This RTOS was selected

for a variety of reasons, including reliability, ease of use, low cost, widespread use, and

the maturity of the product due to the extensive experience of its developers. This RTOS

contains most of the features found in contemporary RTOSes, as well as several advanced

features that are not. Another notable feature of this RTOS is the consistent and readable

coding convention used within its application programming interface (API). Developing

applications is highly intuitive because of the logical approach of the API.

Although I chose the C programming language for this book, you could use C

instead

for any of the applications described in this book.

There is a CD included with this book that contains a limited ThreadX 3 system. You may

use this system to perform your own experiments, run the included demonstration system,

and experiment with the projects described throughout the book.

Typographical conventions are used throughout this book so that key concepts are

communicated easily and unambiguously. For example, keywords such as main or int are

displayed in a distinctive typeface, whether these keywords are in a program or appear

in the discussion about a program. This typeface is also used for all program segment

listings or when actual input or output is illustrated. When an identiﬁ er name such as

MyVar is used in the narrative portion of the book, it will appear in italics. The italics

typeface will also be used when new topics are introduced or to provide emphasis.

2 ThreadX is a registered trademark of Express Logic, Inc. The ThreadX API, associated data

structures, and data types are copyrights of Express Logic, Inc. MIPS is a registered trademark of

MIPS Processors, Inc.

3 Express Logic, Inc. has granted permission to use this demonstration system for the sample

systems and the case study in this book.

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