[...]... on the bus • USB mass- storage protocol Every USB mass- storage device must detect and respond to requests that are specific to the USB mass- storage class • SCSI commands USB hosts access mass- storage devices via commands originally developed for devices that use the Small Computer Systems Interface (SCSI) • Media-specific protocol The storage media’s controller typically supports a command set for accessing... With the addition of a USB mass- storage interface, any of these devices can use USB to exchange files with PCs and other USB hosts Generic storage devices are readily available and inexpensive Unless you’re employed by a storage- device manufacturer, there isn’t much point in designing and programming your own generic devices But special-purpose USB storage devices are useful in many embedded systems, including... data storage, whether or not the devices have USB interfaces Interfaces, Protocols, and Technologies Designing and programming a USB mass- storage device or embedded USB host involves a variety of interfaces, protocols, and structures Every USB mass- storage device must support two interfaces: • A USB device interface to enable the device to communicate with a PC or other USB host • An interface between... function as USB hosts that can access files in off-the-shelf USB flash drives and hard drives xiii Introduction If you’re involved with designing or programming devices that incorporate a USB mass- storage device or host interface, this book will help you get your projects up and running You’ll also find the book useful if you’re designing or programming devices that use flash-memory cards for data storage, ... Adding storage capabilities and a USB interface to an embedded system requires hardware and firmware to support accessing the storage media and communicating over the USB interface Devices An embedded system that functions as a USB mass- storage device requires the following hardware (Figure 1-1): • A microcontroller or other CPU or intelligent hardware to manage the embedded system’s operation • A USB. .. connected to a USB port on the host The hardware or firmware in an embedded USB mass- storage host must provide the following functions: • Issue USB requests and initiate other events on the bus to identify attached devices and manage traffic and power on the bus • Issue USB mass- storage requests that ask for status information or specify actions for the device to perform • Issue SCSI commands in USB transfers... and respond to USB mass- storage requests for information or actions from the device • Detect and respond to SCSI commands received in USB transfers These industry-standard commands read and write blocks of data in the storage media, request status information, and control device operation In addition, devices that create, read, or write to files and directories on their own (not via a USB host) must... bus Yes Other Considerations A storage device isn’t the solution for every application, however • Mass- storage firmware is complex A USB mass- storage device must support the USB protocols required for all USB devices as well as class-specific mass- storage protocols If the device firmware needs to create, read, or write to files and directories on its own (not via the USB interface), the firmware must...Contents 11 Embedded Hosts 259 Inside an Embedded Host 259 OTG Devices and Conventional Hosts 260 General Host Functions 260 Mass Storage Functions 261 Handling Non-compliant Devices 263 Host Options 266 Cypress EZ-HOST 266 Host Software 267 A Mass- storage Host Module 267 Index 271 x Acknowledgements Many people helped in the development and writing of this book My technical... you’re using a mass- storage device A computer’s hard drive is a mass- storage device, as are flash, CD, and DVD drives Devices with dedicated functions—data loggers, robots, and other embedded systems—can use mass storage as well Every mass- storage device contains a microcontroller, microprocessor, or other intelligent hardware that knows how to access the contents of the storage media A USB device controller . alt="" USB Mass Storage Designing and Programming Devices and Embedded Hosts Jan Axelson Lakeview Research LLC Madison, WI USB Mass Storage: Designing and Programming Devices and Embedded Hosts by. USB mass- storage protocol. Every USB mass- storage device must detect and respond to requests that are specific to the USB mass- storage class. • SCSI commands. USB hosts access mass- storage devices. interfaces. Interfaces, Protocols, and Technologies Designing and programming a USB mass- storage device or embedded USB host involves a variety of interfaces, protocols, and structures. Every USB mass- storage device