Date post: | 13-Jan-2015 |
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USB 3.0USB 3.0
Content OverviewContent Overview• Introduction to USB 3.0• History of USB
o Overview
• Time chart• Connectors• Architecture• Dataflow• Packets• Summary
IntroductionIntroduction• Universal Serial Bus (USB) is a standard interface
for connecting peripheral devices to a host computer. The USB system was originally devised by a group of companies including Compaq, Digital Equipment, IBM, Intel, Microsoft, and Northern Telecom to replace the existing mixed connector system with a simpler architecture.
• The USB standard is maintained and enforced by the USB Implementers Forum (USB-IF).
IntroductionIntroductionUSB 3.0 specification include a number of significant changes including:•Higher data transfer rate (up to 5 Gbps)•Increased bus power and current draw•Improved power management•Full duplex data communications•Link Training and Status State Machine (LTSSM)•Interrupt driven, instead of polling•Streaming interface for more efficient data transfers
USB HISTORYUSB HISTORYUSB 1.0 specification introduced in 1994USB 2.0 specification finalized in 2001Became popular due to cost/benefit
advantage Eg. IEEE 1394 – high bandwidth, high cost
Three generations of USB USB 1.0 USB 2.0 USB 3.0 and WUSB
Also referred to as SuperSpeed USB Speeds 10x faster than USB 2.0 (5 Gbps in
controlled test environment) Extensible – Designed to scale > 25Gbps
Optimized power efficiency No device polling (asynchronous notifications) Lower active and idle power requirements
Backward compatible with USB 2.0 USB 2.0 device will work with USB 3.0 host USB 3.0 device will work with USB 2.0 host
USB:TIME CHARTUSB:TIME CHART
USB 3.0 - USB 3.0 - TimelineTimeline
Promoter Group: Hewlett-Packard, Intel, Microsoft, NEC, ST-NXP Wireless and Texas Instrument
Contributors Group contained over 200 companies (Nov 2007)
USB 3.0 Specification became available Nov 2008
USB 3.0 USB 3.0
ConnectorsConnectors
Added pins for SuperSpeed USB signals
Compatibility for USB 2.0 connectors
USB 3.0 Standard B connector (middle) contains power and ground pins for device to supply power
Physical FeaturesPhysical Features
USB 2.0 Male Ports USB 2.0 Port and USB 3.0 Male Port
Current Devices using USB 3.0 Current Devices using USB 3.0
USB 3.0 ARCHITECTURE
15
• USB 3.0 is a physical SuperSpeed bus combined in parallel with a physical USB 2.0 bus
USB 2.0 VS USB 3.0 USB 2.0 VS USB 3.0 • Usb 2.0 uses a 3-part transaction(token,
data,handshake)• In USB 3.0, for OUT transactions, the token is
incorporated in the data packet.• For IN transactions the token is replaced by a
handshake.• USB3.0 supports continuous data bursting.
• USB3.0 is a dual-simplex unicast bus so INs and OUTs can occur concurrently.
• USB3.0 uses asynchronous notifications instead of polling.
• USB3.0 supports streaming for bulk endpoints.• USB3.0 allows isochronous devices to
autonomously enter power link states between service intervals.
• USB3.0 Adds a mechanism for devices to send a Bus Interval Adjustment Message.it allows the driver to change the SOF interval to +/- 13.333 microseconds.
• USB3.0 Supports link level power management that may be initiated from either end of the link.
• In USB3.0 the transmitter may send multiple data packets before receiving handshake unlike in USB2.0.
• USB3.0 packets are send over a dedicated path between host and target device unlike USB2.0 which broadcasts.
• Asynchronous notifications replace USB2.0 polling (this allows devices and links to go into power states, it preserves the bandwidth also)
Super speed packetsSuper speed packets• Link Management Packets• -Traverses only the pair of directly connecting
ports• -Used to manage that link• Transaction packet• -Traverse all links in the path directly connecting
the host and a device.• - Use to control the flow of data packets,
configure device and hub.
Data Packet-Traverse all links in the path directly connecting the host and a device- Consist of two parts-Data Packet Header (DPH) Similar to TP-Data Packet Payload (DPP) Data BlockIsochronous Timestamp Packet-Multicast packet sent by host to all active links
ConclusionConclusion• The current total of PCs and peripherals that can be
connected via USB totals over 10 billion, and this number is increasing by three billion each year. A growing proportion of these now use 3.0 technology, as the majority of motherboard, PC and notebook manufacturers have already launched products with a 3.0 port. According to studies, by 2015 the number of devices with USB 3.0 will have surpassed two billion, and the ratio of computers with built-in USB SuperSpeed connections is expected to reach 100%. According to In-Stat surveys, around 70 million USB 3.0 devices were sold in 2011, but by 2014 this number is predicted by the analysts to rise to one billion.