usbmassbulk_10_im

Universal Serial Bus Mass Storage Class Bulk-Only Transport Revision 1.0 September 31, 1999 Revision 1.0 September 31, 1999 USB Mass Storage Class – Bulk Only Transport Page 2 of 22 Change History Revision Issue Date Comments 0.7 September 23, 1998 Initial draft, pre-release 0.8 October 6, 1998 Revisions made at the Mass Storage DWG review – Irvine, CA 0.9 October 21, 1998 Revisions made at the Mass Storage DWG review – Plano, TX 0.9a January 5, 1999 Revisions made at the Mass Storage DWG review – Tigard, OR 0.9b February 1, 1999 Additions of LUN support - Milpitas, CA 1.0[RC1] March 5, 1999 RR review - Midway, UT 1.0[RC2] March 23, 1999 Revisions from reflector review comments 1.0[RC3] March 29, 1999 Specification line by line review – Milpitas, CA 1.0[RC4] June 21, 1999 Specification line by line review – RR21 – Milpitas, CA 1.0 September 31, 1999 Final Revision edits for Released Document – SLC, UT USB Device Class Definition for Mass Storage Devices Copyright © 1998, 1999, USB Implementers Forum. All rights reserved. INTELLECTUAL PROPERTY DISCLAIMER THIS SPECIFICATION IS PROVIDED “AS IS” WITH NO WARRANTIES WHATSOEVER INCLUDING ANY WARRANTY OF MERCHANTABILITY, FITNESS FOR ANY PARTICULAR PURPOSE, OR ANY WARRANTY OTHERWISE ARISING OUT OF ANY PROPOSAL, SPECIFICATION, OR SAMPLE. A LICENSE IS HEREBY GRANTED TO REPRODUCE AND DISTRIBUTE THIS SPECIFICATION FOR INTERNAL USE ONLY. NO OTHER LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY OTHER INTELLECTUAL PROPERTY RIGHTS IS GRANTED OR INTENDED HEREBY. AUTHORS OF THIS SPECIFICATION DISCLAIM ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF PROPRIETARY RIGHTS, RELATING TO IMPLEMENTATION OF INFORMATION IN THIS SPECIFICATION. AUTHORS OF THIS SPECIFICATION ALSO DO NOT WARRANT OR REPRESENT THAT SUCH IMPLEMENTATION(S) WILL NOT INFRINGE SUCH RIGHTS. Contributors Al Rickey, Phoenix Technologies Alan Haffner, Lexar Media Bill Stanley, Adaptec Calaimany Bhoopathi, Shuttle Technology Curtis E. Stevens, Phoenix Technologies Darrell Redford , Iomega Corporation Dave Gilbert, In-System Design David G. Lawrence, Global Technology Development David L. Jolley, Iomega Corporation David Luke, In-System Design Eric Luttman, In-System Design Glen Slick, Microsoft Corporation Hiromichi Oribe, Hagiwara Sys-ComCo Jan Matejica, PIMC/Philips Jim Blackson, Y-E Data, Inc Jim Quigley, Iomega Corporation Johan Craeybeckk, PIMC/Philips Jordan Brown, Sun Microsystems Kenny Chu, Hagiwara Sys-ComCo Kenichi Hamada, Y-E Data, Inc Mark Williams, Microsoft Corporation Masayuki Kitagawa, Mitsumi Mike Chen, CMD Technology Mike Glass, Microsoft Corporation Mike Liebow, eTEK Labs Mike Nguyen, TEAC Mike Poulsen, Iomega Corporation Moto Watanabe, Hagiwara N.R. Devanathan, Shuttle Technology Paramita Das, Sun Microsystems Pat LaVarre, Iomega Corporation Peter S'Heeren, PIMC/Philips Ryota Okazaki, NEC Corporation Sadao Yabuki, TEAC Shigeyoshi Hashi, NEC Corporation Shing F. Lin, Adaptec Steve Bayless, Hewlett-Packard Steve Kolokowsky, Anchor Chips Steven Smith, eTEK Labs Terry Moore, MCCI Tim Bradshaw, Iomega Corp Toyoko Shimizu, Y-E Data, Inc Trenton Henry, SMSC Troy Davidson, Iomega Corporation Tsuyoshi Osawa, TEAC Yuji Oishi, Hagiwara Sys-Com Co Ltd Revision 1.0 September 31, 1999 USB Mass Storage Class – Bulk Only Transport Page 3 of 22 Table of Contents 1 Specification Overview and Scope................................................................................... 5 1.1 Scope............................................................................................................................................................. 5 2 Terms and Abbreviations .................................................................................................. 6 2.1 Conventions .................................................................................................................................................. 6 2.2 Definitions..................................................................................................................................................... 6 3 Functional Characteristics ................................................................................................ 7 3.1 Bulk-Only Mass Storage Reset (class-specific request)................................................................................ 7 3.2 Get Max LUN (class-specific request).......................................................................................................... 7 3.3 Host/Device Packet Transfer Order .............................................................................................................. 8 3.4 Command Queuing ....................................................................................................................................... 8 3.5 Bi-Directional Command Protocol................................................................................................................ 8 4 Standard Descriptors ........................................................................................................ 9 4.1 Device Descriptor.......................................................................................................................................... 9 4.1.1 Serial Number ....................................................................................................................................... 9 4.1.2 Valid Serial Number Characters.......................................................................................................... 10 4.2 Configuration Descriptor ............................................................................................................................ 10 4.3 Interface Descriptors ................................................................................................................................... 11 4.4 Endpoint Descriptors................................................................................................................................... 11 4.4.1 Bulk-In Endpoint................................................................................................................................. 11 4.4.2 Bulk-Out Endpoint .............................................................................................................................. 12 5 Command/Data/Status Protocol ..................................................................................... 13 5.1 Command Block Wrapper (CBW).............................................................................................................. 13 5.2 Command Status Wrapper (CSW) .............................................................................................................. 14 5.3 Data Transfer Conditions ............................................................................................................................ 15 5.3.1 Command Transport............................................................................................................................ 15 5.3.2 Data Transport..................................................................................................................................... 15 5.3.3 Status Transport .................................................................................................................................. 16 5.3.4 Reset Recovery.................................................................................................................................... 16 6 Host/Device Data Transfers ............................................................................................ 17 6.1 Overview..................................................................................................................................................... 17 6.2 Valid and Meaningful CBW ....................................................................................................................... 17 6.2.1 Valid CBW.......................................................................................................................................... 17 6.2.2 Meaningful CBW ................................................................................................................................ 17 6.3 Valid and Meaningful CSW........................................................................................................................ 17 6.3.1 Valid CSW .......................................................................................................................................... 17 6.3.2 Meaningful CSW ................................................................................................................................ 17 6.4 Device Error Handling ................................................................................................................................ 17 6.5 Host Error Handling.................................................................................................................................... 18 6.6 Error Classes ............................................................................................................................................... 18 6.6.1 CBW Not Valid................................................................................................................................... 18 6.6.2 Internal Device Error........................................................................................................................... 18 6.6.3 Host/Device Disagreements ................................................................................................................ 18 6.6.4 Command Failure................................................................................................................................ 18 6.7 The Thirteen Cases...................................................................................................................................... 18 6.7.1 Hn - Host expects no data transfers..................................................................................................... 19 6.7.2 Hi - Host expects to receive data from the device............................................................................... 20 6.7.3 Ho - Host expects to send data to the device....................................................................................... 21 Revision 1.0 September 31, 1999 USB Mass Storage Class – Bulk Only Transport Page 4 of 22 List of Tables Table 3.1 – Bulk-Only Mass Storage Reset .............................................................................................................7 Table 3.2 –Get Max LUN ........................................................................................................................................7 Table 4.1 - Device Descriptor ..................................................................................................................................9 Table 4.2 - Example Serial Number Format ..........................................................................................................10 Table 4.3 - Valid Serial Number Characters ..........................................................................................................10 Table 4.4 - Configuration Descriptor .....................................................................................................................10 Table 4.5 – Bulk-Only Data Interface Descriptor ..................................................................................................11 Table 4.6 - Bulk-In Endpoint Descriptor ...............................................................................................................11 Table 4.7 – Bulk-Out Endpoint Descriptor ............................................................................................................12 Table 5.1 - Command Block Wrapper ...................................................................................................................13 Table 5.2 - Command Status Wrapper ...................................................................................................................14 Table 5.3 - Command Block Status Values ...........................................................................................................15 Table 6.1 - Host/Device Data Transfer Matrix.......................................................................................................19 List of Figures Figure 1 - Command/Data/Status Flow ................................................................................................................. 13 Figure 2 - Status Transport Flow .......................................................................................................................... 15 Revision 1.0 September 31, 1999 USB Mass Storage Class – Bulk Only Transport Page 5 of 22 1 Specification Overview and Scope 1.1 Scope A familiarity with the USB 1.0 and 1.1 Specifications and the USB Mass Storage Class Specification Overview is assumed. This specification addresses Bulk-Only Transport, or in other words, transport of command, data, and status occurring solely via Bulk endpoints (not via Interrupt or Control endpoints). This specification only uses the default pipe to clear a STALL condition on the Bulk endpoints and to issue class-specific requests as defined below. This specification does not require the use of an Interrupt endpoint. This specification defines support for logical units that share common device characteristics. Although this feature provides the support necessary to allow like mass storage devices to share a common USB interface descriptor, it is not intended to be used to implement interface bridge devices. Revision 1.0 September 31, 1999 USB Mass Storage Class – Bulk Only Transport Page 6 of 22 2 Terms and Abbreviations 2.1 Conventions Numbers without annotation are decimal ----------------------------------------------- 1, 17, 23 Hexadecimal numbers are followed by an ‘h’------------------------------------------- 1Fh, FCh, 38h Binary numbers are followed by a ‘b’ ---------------------------------------------------- 011b, 101b, 01110010b Words in italics indicate terms defined by USB or by this specification ----------- bRequest, dCSWTag 2.2 Definitions Command Block Wrapper (CBW) A packet containing a command block and associated information. Command Status Wrapper (CSW) A packet containing the status of a command block. Data-In Indicates a transfer of data IN from the device to the host. Data-Out Indicates a transfer of data OUT from the host to the device. Device Request Requests from the host to the device using the default pipe. Phase Error An error returned by the device indicating that the results of processing further CBWs will be indeterminate until the device is reset. Processed Data received and controlled internally by the device to the point that the host need no longer be concerned about it. Relevant The amount of the data sent to the host by the device that is significant. Reset Recovery An error recovery procedure by which the host prepares the device for further CBWs. Thin Diagonal Cases where the host and device are in complete agreement about the data transfer. See Chapter 6 - Host/Device Data Transfers, for additional information regarding error cases and the "thin diagonal." Revision 1.0 September 31, 1999 USB Mass Storage Class – Bulk Only Transport Page 7 of 22 3 Functional Characteristics 3.1 Bulk-Only Mass Storage Reset (class-specific request) This request is used to reset the mass storage device and its associated interface. This class-specific request shall ready the device for the next CBW from the host. The host shall send this request via the default pipe to the device. The device shall preserve the value of its bulk data toggle bits and endpoint STALL conditions despite the Bulk-Only Mass Storage Reset. The device shall NAK the status stage of the device request until the Bulk-Only Mass Storage Reset is complete. To issue the Bulk-Only Mass Storage Reset the host shall issue a device request on the default pipe of: • bmRequestType: Class, Interface, host to device • bRequest field set to 255 (FFh) • wValue field set to 0 • wIndex field set to the interface number • wLength field set to 0 Table 3.1 – Bulk-Only Mass Storage Reset bmRequestType bRequest wValue wIndex wLength Data 00100001b 11111111b 0000h Interface 0000h none 3.2 Get Max LUN (class-specific request) The device may implement several logical units that share common device characteristics. The host uses bCBWLUN (see 5.1 Command Block Wrapper (CBW)) to designate which logical unit of the device is the destination of the CBW. The Get Max LUN device request is used to determine the number of logical units supported by the device. Logical Unit Numbers on the device shall be numbered contiguously starting from LUN 0 to a maximum LUN of 15 (Fh). To issue a Get Max LUN device request, the host shall issue a device request on the default pipe of: • bmRequestType: Class, Interface, device to host • bRequest field set to 254 (FEh) • wValue field set to 0 • wIndex field set to the interface number • wLength field set to 1 Table 3.2 –Get Max LUN bmRequestType bRequest wValue wIndex wLength Data 10100001b 11111110b 0000h Interface 0001h 1 byte The device shall return one byte of data that contains the maximum LUN supported by the device. For example, if the device supports four LUNs then the LUNs would be numbered from 0 to 3 and the return value would be 3. If no LUN is associated with the device, the value returned shall be 0. The host shall not send a command block wrapper (CBW) to a non-existing LUN. Devices that do not support multiple LUNs may STALL this command. Revision 1.0 September 31, 1999 USB Mass Storage Class – Bulk Only Transport Page 8 of 22 3.3 Host/Device Packet Transfer Order The host shall send the CBW before the associated Data-Out, and the device shall send Data-In after the associated CBW and before the associated CSW. The host may request Data-In or CSW before sending the associated CBW. If the dCBWDataTransferLength is zero, the device and the host shall transfer no data between the CBW and the associated CSW. 3.4 Command Queuing The host shall not transfer a CBW to the device until the host has received the CSW for any outstanding CBW. If the host issues two consecutive CBWs without an intervening CSW or reset, the device response to the second CBW is indeterminate. 3.5 Bi-Directional Command Protocol This specification does not provide for bi-directional data transfer in a single command. Revision 1.0 September 31, 1999 USB Mass Storage Class – Bulk Only Transport Page 9 of 22 4 Standard Descriptors The device shall support the following standard USB descriptors: • Device. Each USB device has one device descriptor (per USB Specification). • Configuration. Each USB device has one default configuration descriptor, which supports at least one interface. • Interface. The device shall support at least one interface, known herein as the Bulk-Only Data Interface. Some devices may support additional interfaces, to provide other capabilities. • Endpoint. The device shall support the following endpoints, in addition to the default pipe that is required of all USB devices: (a) Bulk-In endpoint (b) Bulk-Out endpoint Some devices may support additional endpoints, to provide other capabilities. The host shall use the first reported Bulk-In and Bulk-Out endpoints for the selected interface. • String. The device shall supply a unique serial number as detailed in 4.1.1 - Serial Number. This specification defines no class-specific descriptors. The rest of this section describes the standard USB device, configuration, interface, endpoint, and string descriptors for the d