etech 6 - superspeed or supersede

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14 eTech - ISSUE 6 eTech - ISSUE 6 15 Will USB 3.0 ring the death knell for slower serial interfaces? USB 3.0 has arrived; at over 10 times faster than USB 2.0 it promises to provide quicker file transfer between enabled devices, feeding consumers’ insatiable appetite for storing, streaming and sharing high bandwidth data such as multimedia files. As with previous incarnations of the universal serial bus, and holding fast with its underlying premise of ease of use, USB 3.0 (or SuperSpeed USB as it has become known) will provide backwards compatibility with USB 2.0, even though it is electrically and mechanically quite different. In order to reach the blisteringly high 5Gbit/s bandwidth it uses two differential pairs; one for transmitting and one for receiving, as opposed to the single differential pair for tx/rx as used in USB 2.0. To accommodate this without sacrificing compatibility, the specification adds four additional wires to the cable assembly. This, in turn, necessitates a different connector profile but in order to make it physically compatible with the existing USB user base, the additional connections are located at the back of the connector, behind the existing USB 2.0 connections. This clever innovation does have some implications, however. It means that only Standard-A receptacles (the ones most frequently found on PCs) will accept both USB 2.0 and SuperSpeed 3.0 Standard-A plugs. Standard-B, Powered-B, Micro-B and Micro-AB receptacles (the ones now commonly found on portable devices) will only offer backwards Over 10 times faster than USB 2.0 it promises to provide quicker file transfer between enabled devices SuperSpeed or Supersede? compatibility; USB 2.0 receptacles won’t be able to accept USB 3.0 plugs as they are physically larger, however USB 3.0 receptacles will accept USB 2.0 plugs thanks to the connector’s design. Beyond the physical differences, the protocol used by SuperSpeed is significantly different from its predecessors, although this will be largely transparent to the user. It will require a new generation of controllers and drivers, the availability of which will be significant in helping USB 3.0 realise its full potential. The SuperSpeed interface uses full duplex transfer, thanks to the use of two independent differential channels. Also, the use of a packet based protocol makes the data routable between host and device, as opposed to the broadcast method used in USB 2.0, all of which contributes to achieving the higher bandwidth speeds. Predominantly this no longer relies on polling, or asking each peripheral whether it has data to send, meaning the bus is only active when data is being moved, which has the added benefit of improving power management, which is now addressed at every layer of the interface to deliver a significant power saving. For instance, at the link layer there are four link states, which can be selected to trade off the power consumed against the latency of the interface. Also, the USB 3.0 specification increases the amount of power that a host can distribute, from 500mA to 900mA. Support for the new USB 3.0 receptacle will, of course, take time but there are a number of PCI bus expansion cards available for PCs that offer the new interface, while newer PCs, laptops and other devices will be able to support the standard natively. Software support will come in the form of drivers, which will need to be added to all the operating systems in circulation, although initially this may also involve peripheral manufacturers developing drivers for the relevant OS, too. With high speed serial communications comes a need for comprehensive test and measurement during the development phase and in response to this need, leading T&M companies including LeCroy and Tektronix now offer automated test suites for USB 3.0, along with the necessary probes and interface hardware for their respective oscilloscopes. The primary appeal of USB 3.0 is its high speed and as it becomes more widely adopted, it will create opportunities for high speed peripherals; external hard drive manufacturers are already announcing products, such as Buffalo Technology’s latest range of USB 3.0 enabled storage solutions which was announced at the recent Consumer Electronics Show (CES) in Las Vegas. CES 2011 was also the venue for a number of other announcements around USB 3.0, such as Genesys Logic’s introduction of a range of controllers including a 4-port hub controller, flash card reader controller and a SATA bridge controller. VIA Labs also used CES 2011 to demonstrate its range of USB 3.0 controllers. Speculation that USB 3.0 will displace USB 2.0 has, inevitably, caused some providers to question whether it is commercially viable to continue to invest in USB 2.0 development. The answer is almost certainly yes, because although SuperSpeed offers many benefits, it is unlikely to be cost-competitive in all applications. The undeniable appeal of USB coupled with the benefits of SuperSpeed and its compatibility with USB 2.0 may even regenerate the market for USB in general, as no other serial interface offers the same level of convenience or, with the advent of SuperSpeed, the same high bandwidth. Find the latest USB 3.0 ranges at rswww.com/electronics Get more online... Share your thoughts on USB 3.0 Superspeed at www.designspark.com

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Page 1: eTech 6 - Superspeed or supersede

14 eTech - ISSUE 6 eTech - ISSUE 6 15

Will USb 3.0 ring the death knell for slower serial interfaces?

USB 3.0 has arrived; at over 10 times faster than USB 2.0 it promises to provide quicker file transfer

between enabled devices, feeding consumers’ insatiable appetite for storing, streaming and sharing high bandwidth data such as multimedia files. As with previous incarnations of the universal serial bus, and holding fast with its underlying premise of ease of use, USB 3.0 (or SuperSpeed USB as it has become known) will provide backwards compatibility with USB 2.0, even though it is electrically and mechanically quite different.

In order to reach the blisteringly high 5Gbit/s bandwidth it uses two differential pairs; one for transmitting and one for receiving, as opposed to the single differential pair for tx/rx as used in USB 2.0. To accommodate this without sacrificing compatibility, the specification adds four additional wires to the cable assembly. This, in turn, necessitates a different connector profile but in order to make it physically compatible with the existing USB user base, the additional connections are located at the back of the connector, behind the existing USB 2.0 connections.

This clever innovation does have some implications, however. It means that only Standard-A receptacles (the ones most frequently found on PCs) will accept both USB 2.0 and SuperSpeed 3.0 Standard-A plugs. Standard-B, Powered-B, Micro-B and Micro-AB receptacles (the ones now commonly found on portable devices) will only offer backwards

“ Over 10 times faster than

USb 2.0 it promises to

provide quicker file transfer between

enabled devices”

SuperSpeedor

Supersede?compatibility; USB 2.0 receptacles won’t be able to accept USB 3.0 plugs as they are physically larger, however USB 3.0 receptacles will accept USB 2.0 plugs thanks to the connector’s design.

Beyond the physical differences, the protocol used by SuperSpeed is significantly different from its predecessors, although this will be largely transparent to the user. It will require a new generation of controllers and drivers, the availability of which will be significant in helping USB 3.0 realise its full potential.

The SuperSpeed interface uses full duplex transfer, thanks to the use of two independent differential channels. Also, the use of a packet based protocol makes the data routable between host and device, as opposed to the broadcast method used in USB 2.0, all of which contributes to achieving the higher bandwidth speeds.

Predominantly this no longer relies on polling, or asking each peripheral whether it has data to send, meaning the bus is only active when data is being moved, which has the added benefit of improving power management, which is now addressed at every layer of the interface to deliver a significant power saving. For instance, at the link layer there are four link states, which can be selected to trade off the power consumed against the latency of the interface. Also, the USB 3.0 specification increases the amount of power that a host can distribute, from 500mA to 900mA.

Support for the new USB 3.0 receptacle will, of course, take time but there are a number of PCI bus expansion cards available for PCs that offer the new interface, while newer PCs, laptops and other devices will be able to support the standard natively. Software support will come in the form of drivers, which will need to be added to all the operating systems in circulation, although initially this may also involve peripheral manufacturers developing drivers for the relevant OS, too.

With high speed serial communications comes a need for comprehensive test and measurement during the development phase and in response to this need, leading T&M companies including LeCroy and Tektronix now offer automated test suites for USB 3.0, along with the necessary probes and interface hardware for their respective oscilloscopes.

The primary appeal of USB 3.0 is its high speed and as it becomes more widely adopted, it will create opportunities for high speed peripherals;

external hard drive manufacturers are already announcing products, such as Buffalo Technology’s latest range of USB 3.0 enabled storage solutions which was announced at the recent Consumer Electronics Show (CES) in Las Vegas.

CES 2011 was also the venue for a number of other announcements around USB 3.0, such as Genesys Logic’s introduction of a range of controllers including a 4-port hub controller, flash card reader controller and a SATA bridge controller. VIA Labs also used CES 2011 to demonstrate its range of USB 3.0 controllers.

Speculation that USB 3.0 will displace USB 2.0 has, inevitably, caused some providers to question whether it is commercially viable to continue to invest in USB 2.0 development. The answer is almost certainly yes, because although SuperSpeed offers many benefits, it is unlikely to be cost-competitive in all applications.

The undeniable appeal of USB coupled with the benefits of SuperSpeed and its compatibility with USB 2.0 may even regenerate the market for USB in general, as no other serial interface offers the same level of convenience or, with the advent of SuperSpeed, the same high bandwidth.

find the latest USb 3.0 ranges at rswww.com/electronics

Get more online...Share your thoughts on USb 3.0 Superspeed at www.designspark.com