Jan Axelson - USB Complete: The Developers Guide

USB Complete: The Developers Guide, Fifth Edition

by Jan Axelson

Copyright 1999-2015 by Janet L. Axelson

All rights reserved. No part of the contents of this book, except the program code, may be reproduced or transmitted in any form or by any means without the written permission of the publisher. The program code may be stored and executed in a computer system and may be incorporated into computer programs developed by the reader.

The information, computer programs, schematic diagrams, documentation, and other material in this book are provided as is, without warranty of any kind, expressed or implied, including without limitation any warranty concerning the accuracy, adequacy, or completeness of the material or the results obtained from using the material. Neither the publisher nor the author shall be responsible for any claims attributable to errors, omissions, or other inaccuracies in the material in this book. In no event shall the publisher or author be liable for direct, indirect, special, incidental, or consequential damages in connection with, or arising out of, the construction, performance, or other use of the materials contained herein.

Many of the products and company names mentioned herein are the trademarks of their respective holders. PIC and MPLAB are registered trademarks of Microchip Technology Inc. in the U.S.A. and other countries.

Published by Lakeview Research LLC, 5310 Chinook Ln., Madison WI 53704

janaxelson.com

Distributed by Independent Publishers Group (ipgbook.com).

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Printed and bound in the United States of America

ISBN13 978-1-931448-29-1

This book is for developers who are involved with designing or programming devices that use the Universal Serial Bus (USB) interface. If you are a hardware designer, if you write firmware that resides inside USB devices, or if you write applications that communicate with devices, this book is for you.

The USB interface is versatile enough to serve just about any device function. Familiar USB peripherals include mice, keyboards, drives, printers, speakers, and cameras. USB is also suitable for data-acquisition units, control systems, and other devices with specialized functions, including one-of-a-kind designs. The right choices of device hardware, software drivers and development tools and techniques can help you design devices that perform their functions without errors or user aggravation. This book will guide you along the way.

The USB specifications are the ultimate authority on the USB interface, but by design the specification documents omit implementation tips, example code, and information that applies to specific device hardware, software, and other tools and products. This book bridges the gap between the specifications and real-world designs.

These are some of the questions this book answers:

• How can I decide if my device should use a USB interface? Find out whether your device should use USB or another interface. If the choice is USB, youll learn how to decide which of USBs five speedsincluding USB 3.1s SuperSpeed and SuperSpeedPlusand which of USBs four transfer types are appropriate for your application.
• What controller hardware should my device use? Every USB device contains an intelligent controller to manage USB communications. A variety of chip companies offer controller hardware with different architectures and abilities. This book will help you select a controller based on your projects needs, your budget, and your preferences for chip architecture, programming languages, and tools.
• How can applications communicate with my devices? On PCs, applications access a USB device by communicating with the driver the operating system has assigned to the device. Youll learn if your device can use a class driver provided by the host systems operating system. For devices that dont fit a supported class, you can explore options such as Microsofts WinUSB driver, other generic drivers, and custom drivers. Example code shows how to detect and communicate with devices from Visual C# applications.
• What firmware does my device need to support USB communications? Find out how to write firmware that enables your device to respond to USB requests and events and exchange data for any purpose.
• Does my device need its own power supply? The USB interface can provide power to devices, including charging current for battery-powered devices. Learn how to determine if a design can obtain all of its power from the bus, how to meet USBs requirements for conserving power, and how to charge battery-powered devices from the bus.
• How can I implement wireless communications? A variety of USB and other industry standards and technologies enable USB devices to communicate wirelessly. Learn which technology is right for your device.
• How can my device access other USB devices? Find out how to develop a host for an embedded system or a USB On-The-Go device that can function as both a USB device and a limited-capability host that accesses other USB devices.
• How can I ensure reliable operation? All devices must respond to requests and other events on the USB port. The host computer must detect attached devices, locate appropriate drivers, and exchange data with the devices. This book provides tips, example code, and information about debugging software and hardware to help with these tasks.

To understand the material in the book, its helpful to have some experience with digital logic, application programming for PCs and writing embedded code for peripherals. You dont have to know anything about USB.

The core of USB has remained much the same since the release of USB 1.0 in 1996. But the interface has expanded to support faster bus speeds, improved power delivery and management, more device classes, wireless communications, support for embedded systems that access USB devices, and more. New and improved chips and development tools have eased the task of developing devices and the software to access them.

This Fifth Edition is revised and updated throughout. New topics include an introduction to USB 3.1 and SuperSpeedPlus, enhanced power delivery and power management, new abilities using USB Type-C connectors, designing devices that use the WinUSB driver without requiring a vendor-provided INF file, new device classes, and how to use free debugging tools.

Much of the information in this book applies to any device hardware and host computer. The example code for applications uses Visual C#.

To find out more about developing USB devices and the software that communicates with them, I invite you to visit my website, janaxelson.com Youll find code examples and links to articles, products, tools, and other information related to developing USB devices. The website includes a PORTS forum where you can ask questions and discuss topics related to USB and other interfaces.

Corrections and updates to the book will also be available at janaxelson.com. If you find an error, please let me know.

The .NET example code in this book is compatible with the .NET Framework Version 4.5 and later.

Example applications are available for free download from janaxelson.com.

USB is much too big a topic to write about without help. I have many people to thank.

My technical reviewers provided feedback that helped make the book as complete and accurate as possible. With that said, every error in this book is mine and mine alone. For their help with this edition, a big thanks to Paul E. Berg, Lane Hauck, Kosta Koeman, Dhanraj Rajput, and Rajaram Regupathy.