文章目录
- 1 简述
- 2 子类代码
- 3 协议代码
- 参考资料
1 简述
USB Mass Storage Class Working Group (CWG)在发展4种大容量存储类的标准规范，包括：
- USB Mass Storage Class Control/Bulk/Interrupt (CBI) Transport
- USB Mass Storage Class Bulk-Only Transport
- USB Mass Storage Class ATA Command Block
- USB Mass Storage Class UFI Command Specification
而上面这些标准规范所使用的命令集，则是复用原本已存在的协议，包括以下几种：
- Advanced Technology Attachment Packet Interface (ATAPI) for Floppies. SFF-8070i, available fromGlobal Engineering, (800)-854-7179.
- Advanced Technology Attachment Packet Interface (ATAPI) for CD-ROMs. SFF-8020i, available fromGlobal Engineering, (800)-854-7179.
- Advanced Technology Attachment Packet Interface (ATAPI) for Tape. QIC-157. Available at http://www.qic.org/html/standards
- Reduced Block Commands (RBC), T10/1240-D, available at http://www.t10.org/drafts.htm
- Multi-Media Command Set 2 (MMC-2), available at http://www.t10.org/drafts.htm
- SCSI Primary Commands – 2 (SPC-2), Revision 3 or later, available from Global Engineering, (800)-854-7179
- Universal Serial Bus Specification, 1.0 revision or later (also referred to as the USB Specification). Inparticular, see Chapter 9, “USB Device Framework.” Available at http://www.usb.org/developers/devclass.html
2 子类代码
在USB大容量存储设备中有一个接口描述符，接口描述符中有一个bInterfaceSubClass的字段，该字段表明接口所使用的标准协议，具体含义如下图
3 协议代码
接口描述符中还有一个bInterfaceProtocol 的字段，该字段表明接口所使用的传输协议，具体含义如下图
参考资料
Universal Serial Bus Mass Storage Class Specification Overview （Revision 1.1）
