Introduction:-
USB 3.0 is the third major revision of the Universal Serial Bus (USB) standard for computer connectivity. USB 3.0 has transmission speeds of up to 5 GB/s, which is 10 times faster than USB2.0 (480 MB/s). USB 3.0 significantly reduces the time required for data transmission, reduces power consumption, and is downward compatible with USB 2.0. The USB 3.0 Promoter Group announced on 17 November 2008 that the specification of version 3.0 had been completed and had made the transition to the USB implementers forum (USB-IF) the managing body of USB specifications. This move effectively opened the specification to hardware developers for implementation in future products.
The first USB 3.0 consumer products were announced and shipped by BUFFALO TECHNOLOGY in November 2009, while the first certified USB 3.0 consumer products were announced 5 January 2010, at the Las Vegas CONSUMERS ELECTRONICS SHOW (CES) including two motherboards by ASUS and Gigabyte Technologies.
Manufacturers of USB 3.0 host controllers include, but are not limited to,RENASAS Electronic, Fresco Logic, As media, Etron VIA Technoloies,TEXAS Instruments and NVIDIA of November 2010, Renesas is the only company to have passed USB-IF certification, although motherboards for Intel’s sandy bridge processors have been seen with As media and Etron host controllers. On October 28, 2010 HEWLETT PACKWARD released the HP Envy 17 3D featuring a Renesas USB 3.0 Host Controller several months before some of their competitors. AMD is working with Renesas to add its USB 3.0 implementation into its chipsets for its 2011 platforms.
Features:-
A new feature is the "Super Speed" bus, which provides a fourth transfer mode at 5.0 GB/s. The raw throughput is 4 GB/s, and the specification considers it reasonable to achieve 3.2 GB/s (0.4 GB/s or 400 MB/s), or more, after protocol overhead. In order to achieve increased data throughput, USB 3.0 introduces an additional two differential pairs over ‘FULL DUPLEX’ which signaling occurs. This results in a USB 3.0 cable having a total of 8 wires: one power, one ground, two for non-Super Speed data (as one differential pair), four wires for Super Speed data (as two differential pairs), and a shield that was not required in previous specifications. To accommodate the additional pins for Super Speed mode, the physical form factors for USB 3.0 plugs and receptacles have been modified. Standard-A plugs have been extended in length (accordingly the port is deeper) with the Super Speed pins extending beyond the legacy pins. Super Speed Standard-B plugs have the Super Speed pins placed on top of the existing form factor.
To ensure backward compatibility (limited to legacy modes):
- A legacy Standard-A plug will fit a Super Speed Standard-A port;
- A legacy Standard-B plug will fit a Super Speed Standard-B port;
- A Super Speed Standard-A plug will fit a legacy Standard-A port;
Super Speed establishes a communications pipe between the host and each device, in a host-directed protocol. In contrast, USB 2.0 broadcasts packet traffic to all devices.
USB 3.0 extends the bulk transfer type in Super Speed with Streams. This extension allows a host and device to create and transfer multiple streams of data through a single bulk pipe.
New power management features include support of idle, sleep and suspend states, as well as link-, device-, and function-level power management.
The bus power spec has been increased so that a unit load is 150 MA (+50% over minimum using USB 2.0). An un-configured device can still draw only one unit load, but a configured device can draw up to six unit loads (900 MA, an 80% increase over USB 2.0 at a registered maximum of 500 MA). Minimum device operating voltage is dropped from 4.4 V to 4.0 V.
USB 3.0 does not define cable assembly lengths, except that it can be of any length as long as it meets all the requirements defined in the specification. Although electronicdesign.com estimated cables will be limited to 3 m at Super Speed, cables which support Super Speed are already available up to 5 m long.
The technology is similar to a single channel (1×) of PCI Express 2.0(5GB/s), It uses 8B/10B encoding, Linear Feed Back Shift Register (LFSR) scrambling for data and Spread Spectrum. It forces receivers to use low frequency periodic signaling (LFPS), dynamic equalization, and training sequences to ensure fast signal locking.
Availability:-
USB 3.0 support can be added to existing laptop computers with only USB 2.0 and Express card support by using an Express card-to-USB 3.0 adapter to supply USB 3.0 signal support. The Express card cannot itself deliver power, which must be derived from a USB 2.0 ports or an external power supply. Possibilities, depending upon connectors on devices, include:
- Some Expresscard-to-USB 3.0 adapters can be connected by a cable to a USB 2.0 port on the computer, which supplies power
- A cable plugs into the drive and has two USB connectors, one to the USB 3.0 port (signal) and one to a USB 2.0 port (power).
- If the external device has an appropriate connector, it can be powered by an External Power Supply.
Speed issues:-
There have been many reports of USB 3.0 equipment only transferring data at USB 2.0 speed, usually with a message "This USB Mass Storage Device can transfer information faster if you connect it to a Super-Speed USB 3.0 port". This has been due to several causes, including drivers, certain cables specified as USB 3.0 (problems disappeared when a different cable was used), order of starting equipment, equipment needing to be disconnected and reconnected, and overclocked computers.
PINOUTS:-
| USB 3.0 pinouts | |||
| Pin | Color | Signal name | Signal name |
| 1 | Red | VBUS | |
| 2 | White | D− | |
| 3 | Green | D+ | |
| 4 | Black | GND | |
| 5 | Blue | StdA_SSRX− | StdA_SSTX− |
| 6 | Yellow | StdA_SSRX+ | StdA_SSTX+ |
| 7 | Shield | GND_DRAIN | |
| 8 | Purple | StdA_SSTX− | StdA_SSRX− |
| 9 | Orange | StdA_SSTX+ | StdA_SSRX+ |
| Shell | Shell | Shield | |
USB 2.0 vs. USB 3.0:-
The beauty of USB 3.0 is its backward compatibility with USB 2.0; you need a new cable and new host adapter to achieve USB 3.0, but you can still use the device on a USB 2.0 port and achieve typical USB 2.0 performance.
The benefit here is that USB 3.0 is a powered port, so you don't need to have another external power supply running to the drive (as you do with eSATA; unless the eSATA drive you're using is designed to steal power from a USB port while transferring data over the eSATA interface).
Conclusion:-
While we have yet to see any device capable of defining the performance limits of USB 3.0, benchmarks prove it’s a huge step up from USB 2.0, even when using a average desktop hard drive. USB 3.0 is able to match the eSATA controller against which it initially competes, and its 5.0 Gb/s limit will continue to remain competitive, even after 6.0 Gb/s transfers are applied to eSATA.
It produces around 50% more amperage over the same power wires as the USB 2.0 interface it shares, USB 3.0 looks to become the de-facto standard for high-speed portable devices. The marketing power of the USB name, along with its shared connector and compatibility with non-ATA devices, will likely relegate the competing eSATA standard to stationary backup devices. Asus’ solution appears to be the most elegant option because it doesn’t steal pathways from the x16 graphics card slot, but instead relies on a PLX bridge to convert four of the chipset’s 2.5 Gb/s pathways to two 5.0 Gb/s pathways. Yet Gigabyte managed to edge out Asus n write performance by taking its 5.0 Gb/s pathway directly from the CPU, eliminating any middle parts (like the DMI interface connecting Core i7 to P55) that could slow the interface down , while also limiting the PCIe slot to X8 mode.
