USB Complete

USB Complete

Everything You Need

to Develop Custom USB Peripherals

Third Edition

Jan Axelson

Lakeview Research LLC

Madison, WI 53704

USB Complete: Everything You Need to Develop USB Peripherals, Third Edition

by Jan Axelson

Copyright 1999-2005 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 permis￾sion of the publisher. The program code may be stored and executed in a computer sys￾tem 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 pub￾lisher or author be liable for direct, indirect, special, incidental, or consequential dam￾ages 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. PICMicro is a registered trademark of Microchip Technology Inc. in

the U.S.A. and other countries.

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

On the web at www.Lvr.com

Distributed by Independent Publishers Group (www.ipgbook.com).

Cover by Rattray Design. Cover Photo by Bill Bilsley Photography.

Index by Julie Kawabata.

14 13 12 11 10 9 8 7 6 5 4 3 2 1

PDF e-book edition

ISBN13 978-1-931448-03-1

ISBN10 1-931448-03-5

Contents

iii

Contents

Introduction xv

1. USB Basics 1

What USB Can Do 2

Benefits for Users 2

Benefits for Developers 6

Beyond the Hype 10

Evolution of an Interface 13

Original USB 14

USB 2.0 15

USB On-The-Go 16

Wireless USB 16

USB versus IEEE-1394 16

USB versus Ethernet 17

Bus Components 17

Topology 18

Defining Terms 19

Contents

iv

Division of Labor 22

The Host’s Duties 22

The Peripheral’s Duties 25

What about Speed? 28

Developing a Device 29

Elements in the Link 29

Tools for Developing 30

Steps in Developing a Project 30

2. Inside USB Transfers 33

Transfer Basics 34

Enumeration Communications 34

Application Communications 34

Managing Data on the Bus 35

Host Speed and Bus Speed 36

Elements of a Transfer 37

Device Endpoints: the Source and Sink of Data 38

Pipes: Connecting Endpoints to the Host 40

Types of Transfers 40

Stream and Message Pipes 42

Initiating a Transfer 43

Transactions: the Building Blocks of a Transfer 44

Transaction Phases 45

Ensuring that Transfers Are Successful 51

Handshaking 51

Reporting the Status of Control Transfers 55

Error Checking 56

3. A Transfer Type for Every Purpose 61

Control Transfers 61

Availability 62

Structure 62

Data Size 66

Speed 66

Detecting and Handling Errors 68

Bulk Transfers 68

Availability 69

Structure 69

Data Size 69

Speed 71

Detecting and Handling Errors 71

Contents

v

Interrupt Transfers 72

Availability 72

Structure 72

Data Size 73

Speed 73

Detecting and Handling Errors 75

Isochronous Transfers 76

Availability 76

Structure 76

Data Size 79

Speed 79

Detecting and Handling Errors 80

More about Time-critical Transfers 80

Bus Bandwidth 81

Device Capabilities 81

Host Capabilities 82

Host Latencies 83

4. Enumeration: How the Host Learns about Devices 85

The Process 86

Enumeration Steps 87

Enumerating a Hub 91

Device Removal 92

Tips for Successful Enumeration 92

Descriptors 93

Types of Descriptors 94

Device Descriptor 96

Device_qualifier Descriptor 99

Configuration Descriptor 101

Other_speed_configuration Descriptor 103

Interface Association Descriptor 103

Interface Descriptor 106

Endpoint Descriptor 108

String Descriptor 112

Other Standard Descriptors 113

The Microsoft OS Descriptor 114

Descriptors in 2.0-compliant Devices 114

Making 1.x Descriptors 2.0-compliant 114

Detecting the Speed of a Dual-Speed Device 116

Contents

vi

5. Control Transfers:

Structured Requests for Critical Data 117

Elements of a Control Transfer 117

Setup Stage 118

Data Stage 120

Status Stage 122

Handling Errors 124

Device Firmware 125

The Requests 127

Get_Status 129

Clear_Feature 130

Set_Feature 131

Set_Address 132

Get_Descriptor 133

Set_Descriptor 134

Get_Configuration 135

Set_Configuration 136

Get_Interface 137

Set_Interface 138

Synch_Frame 139

Other Control Requests 140

Class-specific Requests 140

Vendor-specific Requests 140

6. Chip Choices 141

Components of a USB Device 142

The USB Controller 143

Other Device Components 145

Simplifying Device Development 148

Device Requirements 149

Chip Documentation 150

Driver Choices 151

Debugging Tools 151

Controllers with Embedded CPUs 154

Microchip PIC18F4550 156

Cypress EZ-USB 157

Cypress enCoRe II 163

Freescale MC68HC908JB16 164

Freescale MCF5482 ColdFire 164

Contents

vii

Controllers that Interface to External CPUs 165

National Semiconductor USBN9603 165

Philips Semiconductors ISP1181B 167

Philips Semiconductors ISP1581 168

PLX Technology NET2272 169

FTDI Chip FT232BM and FT245BM 170

7. Device Classes 177

About Classes 177

Device Working Groups 178

Elements of a Class Specification 178

Defined Classes 181

Audio 181

Chip/Smart Card Interface 189

Communication Devices: Modems and Networks 191

Content Security 198

Device Firmware Upgrade 200

Human Interface 203

IrDA Bridge 206

Mass Storage 208

Printers 213

Still Image Capture: Cameras and Scanners 217

Test and Measurement 220

Video 221

Implementing Non-standard Functions 226

Standard or Custom Driver? 226

Converting from RS-232 227

Converting from the Parallel Port 229

PC-to-PC Communications 229

Using a Generic Driver 231

8. How the Host Communicates 233

Device Driver Basics 233

Insulating Applications from the Details 234

Options for USB Devices 235

User and Kernel Modes 235

WDM Drivers 237

Layered Drivers 238

Communication Flow 243

More Examples 246

Contents

viii

Creating a Custom Driver 247

Writing a Driver from Scratch 247

Using a Driver Toolkit 248

Using GUIDs 249

Device Setup GUIDs 250

Device Interface GUIDs 251

9. Matching a Driver to a Device 253

Using the Device Manager 253

Viewing Devices 254

Property Pages 257

Device Information in the Registry 257

The Hardware Key 258

The Class Key 259

The Driver Key 260

The Service Key 262

Inside INF Files 262

Syntax 265

Sections 266

Using Device Identification Strings 272

Finding a Match 274

Do You Need to Provide an INF File? 276

Tools and Diagnostic Aids 277

Tips for Using INF Files 277

What the User Sees 279

10. Detecting Devices 281

A Brief Guide to Calling API Functions 281

Managed and Unmanaged Code 282

Documentation 284

Using Visual C++ .NET 284

Using Visual Basic .NET 286

Finding Your Device 291

Obtaining the Device Interface GUID 292

Requesting a Pointer to a Device Information Set 293

Identifying a Device Interface 295

Requesting a Structure Containing the Device Path Name 298

Extracting the Device Path Name 301

Closing Communications 302

Contents

ix

Obtaining a Handle 303

Requesting a Communications Handle 303

Closing the Handle 306

Detecting Attachment and Removal 306

About Device Notifications 307

Registering for Device Notifications 307

Capturing Device Change Messages 311

Reading Device Change Messages 312

Retrieving the Device Path Name in the Message 314

Stopping Device Notifications 317

11. Human Interface Devices:

Using Control and Interrupt Transfers 319

What is a HID? 320

Hardware Requirements 321

Firmware Requirements 323

Identifying a Device as a HID 323

The HID Interface 326

HID Class Descriptor 326

Report Descriptors 328

HID-specific Requests 330

Get_Report 332

Get_Idle 333

Get_Protocol 334

Set_Report 335

Set_Idle 336

Set_Protocol 337

Transferring Data 338

About the Example Code 338

Sending Reports via Interrupt Transfers 340

Receiving Reports via Interrupt Transfers 343

Sending Reports via Control Transfers 345

Receiving Reports via Control Transfers 347

12. Human Interface Devices: Reports 351

Report Structure 351

Using the HID Descriptor Tool 352

Control and Data Item Values 354

Item Types 354

Contents

x

The Main Item Type 355

Input, Output, and Feature Items 356

Collection and End Collection Items 360

The Global Item Type 361

Identifying the Report 361

Describing the Data’s Use 363

Converting Units 365

Converting Raw Data 366

Describing the Data’s Size and Format 369

Saving and Restoring Global Items 369

The Local Item Type 370

Physical Descriptors 373

Padding 373

13. Human Interface Devices: Host Application 375

HID API Functions 375

Requesting Information about the HID 376

Sending and Receiving Reports 376

Providing and Using Report Data 378

Managing HID Communications 379

Identifying a Device 379

Reading the Vendor and Product IDs 380

Getting a Pointer to a Buffer with Device Capabilities 384

Getting the Device’s Capabilities 385

Getting the Capabilities of the Buttons and Values 388

Sending and Receiving Reports 388

Sending an Output Report to the Device 389

Reading an Input Report from the Device 392

Writing a Feature Report to the Device 402

Reading a Feature Report from a Device 404

Closing Communications 406

14. Bulk Transfers for Any CPU 407

Two Projects 407

Asynchronous Serial Interface 408

Parallel Interface 414

Host Programming 421

Using the D2XX Direct Driver 422

Selecting a Driver 422

Contents

xi

Performance Tips 426

Speed Considerations 426

Minimizing Latency 427

Preventing Lost Data 428

EEPROM Programming 429

EEPROM Data 429

Editing the Data 429

15. Hubs: the Link between Devices and the Host 433

Hub Basics 434

The Hub Repeater 435

The Transaction Translator 438

The Hub Controller 444

Speed 445

Maintaing an Idle Bus 447

How Many Hubs in Series? 447

The Hub Class 448

Hub Descriptors 448

Hub-class Requests 452

Port Indicators 453

16. Managing Power 455

Powering Options 455

Voltages 456

Which Peripherals Can Use Bus Power? 457

Power Needs 458

Informing the Host 459

Hub Power 461

Power Sources 461

Over-current Protection 462

Power Switching 463

Saving Power 464

Global and Selective Suspends 464

Current Limits for Suspended Devices 464

Resuming Communications 466

Power Management under Windows 467

17. Testing and Debugging 471

Tools 471

Hardware Protocol Analyzers 472

Software Protocol Analyzers 475

Traffic Generators 477

Contents

xii

Testing 477

Compliance Testing 478

WHQL Testing 484

18. Signals and Encoding 489

Bus States 489

Low-speed and Full-speed Bus States 490

High-speed Bus States 492

Data Encoding 494

Staying Synchronized 496

Timing Accuracy 498

Packet Format 499

Fields 499

Inter-packet Delay 501

Test Modes 502

Entering and Exiting Test Modes 502

The Modes 502

19. The Electrical Interface 505

Transceivers and Signals 506

Cable Segments 506

Low- and Full-speed Transceivers 508

High-speed Transceivers 512

Signal Voltages 517

Low and Full Speeds 517

High Speed 518

Cables 518

Conductors 518

Connectors 520

Detachable and Captive Cables 524

Cable Length 524

Ensuring Signal Quality 525

Sources of Noise 526

Balanced Lines 527

Twisted Pairs 527

Shielding 528

Edge Rates 529

Isolated Interfaces 529

Contents

xiii

Wireless Links 530

Cypress WirelessUSB 530

The Wireless USB Initiative 533

Other Options 534

20. Dual-role Devices with USB On-The-Go 535

Device and Host in One 536

Capabilities and Limits 536

Requirements for an OTG Device 538

The OTG Descriptor 545

Feature Codes for HNP 545

OTG Controller Chips 545

Philips ISP1362 546

TransDimension TD242LP 547

Cypress CY7C67200 EZ-OTG 548

Philips ISP1261 Bridge Controller 549

Index 551

Contents

xiv