USB Complete The Developer’s Guide 5th Edition  (English, Paperback, Jan Axelson)

Introduction 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. What's New in the Fifth Edition 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#. From Chapter 4: Enumeration: How the Host Learns about Devices One of a hub’s duties is to detect attachment and removal of devices on its downstream-facing ports. Each hub has an interrupt IN endpoint for reporting these events to the host. On system boot-up, hubs inform the host if any devices are attached including additional downstream hubs and any devices attached to those hubs. After boot-up, a host continues to poll periodically (USB 2.0) or receives ERDY TPs (Enhanced SuperSpeed) that request communications to learn of any newly attached or removed devices. On learning of a new device, the host sends requests to the device’s hub to cause the hub to establish a communications path between the host and device. The host then attempts to enumerate the device by issuing control transfers containing standard USB requests to the device. All USB devices must support control transfers, standard requests, and endpoint zero. For a successful enumeration, the device must respond to requests by returning requested information and taking other requested actions.