Product manual

Spinpoint M9TU-USB 3.0 Product Manual REV 1.0
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USB INTERFACE AND USB COMMANDS
CHAPTER 6 USB INTERFACE AND USB COMMANDS
6.1 Introduction
A Seagate disk drive with an Embedded USB Interface
fully supports and enhances PC mass storage requirements.
The Seagate USB interface conforms to the USB 2.0 and
3.0 standards in Cabling, in Physical Signals, and in
Logical Programming schemes. The Seagate Embedded
USB controller joins the industry premiere VLSI
circuitry with ingenious programming skill that does
not compromise performance or reliability. Seagate
integrates and delivers the cutting edge in technology.
Seagate USB class disk drives are designed to relieve and
to enhance the I/O request processing function of system
drivers.
Figure 6-1 shows how USB Interface constructs.
Figure 6-1: Interlayer Communication Flow
Physical Interface Layer- The bottom layer is a bus interface that transmits and receives packets.
Protocol Layer - The middle layer handles routing data between the bus interface and various endpoints on the
device. An endpoint is the ultimate consumer or provider of data. It may be thought of as a source or sink for
data.
Data Transfer Layer - The top layer is the functionality provided by the serial bus device, for instance, a
mouse or ISDN interface.
6.2 Physical Interface
The physical interface of the USB is described in the mechanical and electrical specifications for the bus.
6.2.1 Mechanical Interface
This chapter provides the mechanical and electrical specifications for the cables, connectors, and cable
assemblies used to interconnect USB devices. The specification includes the dimensions, materials,
electrical, and reliability requirements. This chapter documents minimum requirements for the external
USB interconnect. Substitute material may be used as long as it meets these minimums.
6.2.1.1 Mechanical Overview
All devices have an upstream connection. Upstream and downstream connectors are not mechanically
interchangeable, thus eliminating illegal loopback connections at hubs. The cable has four conductors: a twisted
signal pair of standard gauge and a power pair in a range of permitted gauges. The connector is four- position,
with shielded housing, specified robustness, and ease of attach-detach characteristics.
The USB physical topology consists of connecting the downstream hub port to the upstream port of another
hub or to a device. The USB can operate at four speeds. Super-speed (5 Gb/s), High-speed (480 Mb/s) and
full-speed (12 Mb/s) require the use of a shielded cable with two power conductors and twisted pair signal
conductors. Low-speed (1.5 Mb/s) recommends, but does not require the use of a cable with twisted pair
signal conductors. The connectors are designed to be hot plugged.