Understanding USB. Universal Serial Bus For Interactive & AV Applications. Joseph Cornwall, CTS-D, CTS-I, LEED GA

Transcription

1 Understanding USB Universal Serial Bus For Interactive & AV Applications Joseph Cornwall, CTS-D, CTS-I, LEED GA

2 Our Agenda USB History and Types Dissecting USB Operation Understanding USB Connectivity The Universal Battery USB Power USB Future Technology

3 Universal Serial Bus USB Was Designed To Standardize The Connection Of Computer Peripherals Replaced Serial And Parallel Ports Eliminated The Need For Separate Power Supplies For Devices Allows For Hot Swapping Connect Up To 127 Devices Allows The Flow Of Information Into AND Out Of A Computer (Host)

4 USB History USB Was Designed To Offer Plug and Play Compatibility Replace Serial and Parallel Ports USB 1.1 Released 1998 USB 2.0 Released 2000 USB 3.0 Released 2011 USB 3.1 Released 2013

5 USB 1.1, 2.0 and 3.0 (Aka 3.1 Gen 1)

6 Comparison Of USB 2.0 And 3.0

7 USB Pin Out Pin 1 Vbus Pin 2 D- Pin 3 D+ Pin 4 Ground Pin 1 Ground Pin 2 USB OTG Address Bus Pin 3 D+ Pin 4 D- Pin 5 Vbus

8 Examination Of USB Bus Speeds

9 USB Topology Leverages Asymmetrical Star Topology USB Host May Implement Multiple Controls Root Hub Is Built Into The Host Controller

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11 Round Robin Device Enumeration USB communicates in round robin fashion Device assigned unique 7-bit address Device drivers loaded Transaction translators convert between high-speed, full-speed and low-speed buses

12 Time Is Of The Essence USB 1.1 and 2.0 operate within rigid time constraints Hubs and functions must respond to the host within a tightly defined time frame This tightly defined response time is the reason for cable length limits 5 meters, based on propagation velocity of the signal in the cable

13 USB Logical Channels USB communication is based on logical channels (pipes) 2 types of pipes Stream pipe (unidirectional) for isochronous, interrupt or bulk Message pipe (bi-directional) for control data flow

14 USB Transfer Types Isochronous transfers at some guaranteed data but with possible data loss Interrupt transfers guarantee quick responses (bounded latency) Bulk transfers are for large sporadic transfers using all remaining available bandwidth, but with no guarantees on bandwidth or latency Control transfers are used for short, simple commands or device status response

15 USB Functions Any device that can transmit or receive data is known as a function A mug warmer, for example, doesn t transmit data and is, therefore, not a function Devices may be composite or compound Composite = 2 functions with a virtual hub Compound = 2 functions with an actual hub

16 Compound and Composite A USB compound device appears to the host as A hub with one or more non-removable USB devices embedded Each Function Appears As A Discrete Device Attached To A Hub To The USB System, A Compound Device Occupies Two Tiers

17 Understanding Hubs Hubs consist of 3 components Repeater - connects and releases functions Controller - communicates with the host Transaction translator controls speeds Hubs are self-powered or bus powered

18 Example Of 7-Port USB Hub In Port 1 Port 2 Port 3 Port 4 Tier Occupied Tier Occupied In Port 4 Port 5 Port 6 Port 7

19 Understanding Extender Systems USB s inherent time limitations allow for cable length of no more than 5 meters Hubs regenerate the signal and are repeaters Almost all USB extenders are seen by the host as a hub

20 USB SuperBooster Converts USB signal to a proprietary signal USB superbooster systems do not have to occupy a tier Superbooster systems may use NAK (not acknowledged) communication protocol to get around system latency Data packet not accepted; please retransmit

21 The Universal Battery Existing USB technology specifies a 5V (+/-5%) power supply In USB, power is delivered in quanta of unit loads Single unit load in USB 1.1 & 2.0 is defined as 100mA High-power devices draw up to the maximum number of unit loads permitted (5 unit loads) USB 1.1, 2.0 and 3.1(gen 1) all treat power similarly

22 Practical USB System Analysis The height of cleverness is to be able to conceal it. - Francois de La Rochefoucauld

23 Analysis of Tiers This hub occupies Tier 3 This extender occupies Tier 4 How much power does this device require? Is there more than 1 hub in this IWB? What happens if we add USB speakers with an integral hub? This hidden passive hub occupies Tier 5 How confident are we that this simple classroom system will work? Did we specify a USB tier budget?

24 Analysis of Power If passive, -100mA Bus Powered -100mA How much power does this device require? Hidden Passive Hub -100mA How confident are we that this simple classroom system will work? Did we specify a USB power budget?

25 USBDeview Screen Cap

26 The Next Generation Of Connectivity Any sufficiently advanced technology is indistinguishable from magic Arthur C. Clarke

27 USB Type-C This next generation of USB technology opens the door for the invention of an entirely new, super thin class of devices that consumers haven t even seen yet Designed for 10,000 plug/unplug cycles Robust enough for laptops and tablets; slim enough for personal portables

28 Apple, Google, Microsoft

29 The Conclusion Is The Place Where You Get Tired Of Thinking The best ideas come as jokes. Make your thinking as funny as possible. David M. Ogilvy

30 USB is one of the most successful and long-lived technologies for a reason. USB 1.1 and 2.0 are prevalent in A/V, while USB 3.0 is primarily a desktop solution There is no Interactivity without USB The layered pyramid model of USB connectivity won t change with the introduction of new USB technology USB power is delivered in quanta ensure you understand the power budget of your system! USB Type-C is a revolution in the wings

31 May I answer any Questions?

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