Interconnection Protocols

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Interconnection Protocols

• Berk ÜSTÜNDAG
• Istanbul Technical University
• Computer Engineering Department
• berk_at_cs.itu.edu.tr http//berk.tc

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Contents (Part 3/7)
1.Introduction 1.1 Goals of the lecture 1.2
OSI Reference Model 2. Wired communication
techniques 2.1 Asynchronous Serial
Communication 2.1.1 Unbalanced wired
communication RS232 2.1.2 Balanced wired
communication RS485 / RS422 2.2 Synchronous
Serial Communication 2.2.1 I2C 2.2.2
Microwire 2.2.3 SPI 2.2.4 CAN BUS
2.2.5 USB
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2.2.6 IEEE1394 (Firewire) 3. NonWired
communication techniques 3.1 Optical
Communication 3.1.2 IRDA 3.1.2
Optical Fibers 3.1.3 Laser 3.2 Radio
Frequency Communication 3.2.1 Frequency
allocation (ETSI) 3.2.2 Radiomodems
3.2.3 Bluetooth 3.2.4 IEEE802.11
3.2.5 GPRS, 3G, UMTS
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4. Mobile Data Transfer 4.1 Smart Cards
4.2 Contactless Smart Cards 4.3 Touch
Memory 4.4 Magnetic Strips (Cards) 4.5
PCMCIA cards 5. Application Examples 5.1 GPS
(NMEA protocol), vehicle tracking 5.2 Can
Bus automative applications 5.3 Virtual
Money 5.4 Mobile officers, PDA 5.5 PC
AT keyboard interface 5.6 Pay TV 5.7
Energy meter (PLC-Power line data collection)
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Microwire SPI Interfaces
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The serial peripheral interface (SPI) is a
general purpose synchronous serial interface
originally found on cerrtain Motorola
microcontrollers.
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Parallel Printer Port SPI EEPROM connection
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2.2.5 USB
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What is the Universal Serial Bus? The USB is a
relatively recent way to connect instruments and
devices to the PC. Most new computers have one or
two USB ports, in addition to the familiar RS232
(COM) and parallel ports. You can use the USB
ports to connect peripherals like digital
cameras, printers and data acquisition and
control units.
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• The USB is extremely convenient for data
  acquisition for several reasons.
• The equipment can obtain power from the USB it
  doesn't need to be battery powered or plugged
  into the wall. This makes USB ideal for portable
  data acquisition with a laptop.
• Using a USB hub you can connect many devices to
  one USB port - letting you easily expand your
  system should requirements grow.
• USB ports are provided on most new PCs - no need
  to open the computer and install adaptor cards.
• You can plug in and unplug your equipment
  without switching off your computer or even
  restarting Windows.
• The USB cable can be up to 5 m long. However,
  using USB hubs between cables you can reach 30m.
• Faster speeds than those allowed by RS232
  connections are achievable
• You can use USB devices alongside existing data
  acquisition equipment (such as cards that you've
  installed in your PC or instruments that plug
  directly into the RS232 port).

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Transferring data at 480 Mbps, USB 2.0's claim to
fame is that it's 40 times faster than USB 1.1
and a touch faster than FireWire's 400 Mbps. In
addition, the new standard is backward-compatible
with USB 1.1, so users can continue to use USB
1.1 peripherals (but won't receive the speed
benefits of 2.0). According to Venture
Development Corp. (VDC), a Natick, Mass.-based
analyst firm, this bodes well for USB. The firm's
recent study of cable shipments ("The U.S.
Aftermarket for Computer Accessories, 4th
Edition") shows USB cables made up 30 percent of
total U.S. aftermarket cable shipments in 2001.
VDC predicts USB will overtake other cable types
this year in shipments, contributing to a
predicted annual growth rate of more than 42
percent through 2006.Another boost for USB 2.0
is Microsoft's decision to offer USB 2.0 drivers
for Windows XP. However, the Redmond, Wash.-based
firm does so cautiously, noting there have been
some issues with the drivers. Apple Computer
still remains on the fence regarding USB 2.0,
stating that it's evaluating the upgrade and
weighing it against the upcoming change to the
FireWire standard.
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...the interfacing solution
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Agenda

• USB - ISDN Terminal Adapter (TA)
• Standard TA (PC ISDN card) - USB TA
• Endpoints usage, ISDN data format
• Hardware implementation, Buffering
• B-channel performance
• Layer model USB TA ? PC ISDN card
• D-channel signalization through USB
• D-channel performance
• Hardware platform, tools
• SAB-C541U

• USB basics
• Why USB
• Bus structure
• Enumeration, speed
• Layer model
• Physical interface
• Transfer, transaction, packet

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USBthe interfacing solution
Universal Serial Bus
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Why USB ?

• Ease of Use
• Plug and Play capabilities for Outside the Box
  peripherals

Youwanna more?!
Universal Serial Bus
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USB Target Applications
Very Low cost Ease of Use Dynamic
Attach-Detach Multiple Peripherals
LOW SPEED 10 - 100 Kb/s
Interactive Devices (Game, VR)
USB
USB focus on LOW COST, HIGH VOLUME applications!
Low cost Guaranteed Latency Higher
Bandwidth Ease of Use
ISDN, POTS, PBX, Audio, Imaging, Bulk Devices
MEDIUM SPEED 500Kb/s - 10Mb/s
1394"firewire"
Video Disk LAN
High Bandwidth Very Low Latency Ease of Use
HIGH SPEED 50 - 1000 Mb/s
Universal Serial Bus
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PC Connectivity Vision
Universal Serial Bus
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Hardware Overview...

• Topology
• Tiered Star (Distributes Connectivity Points)
• 127 logical connections (upto 5 meters per
  segment)
• Upto 6 tiers
• ...

Universal Serial Bus
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...Topology...

• Host
• One PC host per system
• Hub
• Provides connecting ports, power, terminations
• Self-Powered or Bus Powered
• Device, Function and End-points
• Device is a collection of function(s)
• Function is a collection of end-points
• Upto 127 functions and 16 end-points per function

Universal Serial Bus
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USB Configuration ProcessEnumeration

• Host Software is responsible for Device
  configuration

• Hot Plug and Play feature
• Device attachment on Hub port
• Device is detected
• Downstream port is enabled
• Configuration of Device by Host

• Process of Configuration is accomplished via
  Control Transfers

Universal Serial Bus, details
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Hardware Overview

• Bus transactions
• Speed 12Mbps full-speed 1.5Mbps low-speed
• Isochronous and Asynchronous
• Media access controlled by host

• Configuration, Hot Plug-And-Play
• Dynamic insertion-removal
• Autoconfiguration on change

• Physical Layer
• 2-wire differential signaling, NRZI coded with
  bit stuffing
• Supply Sourcing 5V
• Signaling at CMOS 3.3V
• 4 pin connector, 4 wire cable

Universal Serial Bus
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Device Abstractions...

• End Point
• Ultimate data source or sink at the device end
• Each endpoint is unidirectional and has a
  transfer type associated with its Peripheral

• Function
• Highest level I/F between device driver and
  function

• Device
• Common features and interactions of devices
• Typically controlled by system software

Universal Serial Bus
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...Device Abstractions
Device, like modem, keyboard mouse, etc
PC
Universal Serial Bus
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USBTransfer types

• Control (e.g. configuration, messages)
• bursty, host initiated (bus management,
  configuration)
• guaranteed bandwith of max. 10
• error-free data delivery guaranteed

• Interrupt (e.g. mouse, joystick....)
• small bursty, low bandwidth required
• error-free data delivery guaranteed
• polling is used (by host) to check for "interrupt
  events
• polling intervall programmable. From 1ms to 255ms
  (FS) 10ms to 255ms (LS)

• Isochronous (e.g. audio, telephony.....)
• for data which need to be periodically sent
• predictable latency on data delivery.
• no error check, error-free data delivery is not
  guaranteed

• Bulk (e.g. printer, scanner, still camera.....)
• non periodic, bursty, ideal for large amounts of
  data
• error-free data delivery guaranteed

...basics
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USB Frame Modelexample
printer
printer
...basics
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Connectors and Cables

• Connectors
• 4-Position with shielded housing
• Positive Retention
• Blind Mating Capabilities

Universal Serial Bus
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USB Hub Function

• Port Control
• Connection detect
• Port Enable/ Disable
• Reset/ Resume Signaling
• Data Switch
• Signal Regeneration
• Robustness/ Recovery
• Power Distribution

Universal Serial Bus
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Power Distribution

• Significant capability of USB
• Eliminate wall adaptors
• Hubs may be self-powered or bus-powered
• Two current levels 100 500 mA
• Overcurrent protection for safety
• Wire gauge options 20-28 AWG
• Suspend
• All devices support suspend
• Enter suspend state after seeing idle bus for 3
  ms
• Suspend current ? 500 ?A from bus
• Resume
• USB devices can cause remote wake-upe.g. Modem
  wakes up the system

Universal Serial Bus
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Voltage Drop

• Voltage drop per wire/connector 0.125 V
• Budget for power switch 0.100 V

Universal Serial Bus
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Data Signaling

• Bi-directional, half-duplex link
• Embedded clock and data
• Differential signal pair
• 12 Mbit / sec Full Speed (FS) bit rate
• 1.5 Mbit / sec Low Speed (LS) bit rate

Universal Serial Bus
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Low Speed

• 1.5 Mb/s
• Unshielded, untwisted cable
• Saves EMI suppression costs
• 1.5 Frequency tolerance
• Driver characteristics
• Rise/ Fall time Min 75ns, Max 300ns
• Required on low speed functions and on the
  downstream ports of Hubs
• Allows very-low-cost devices to be built without
  compromising data rate for faster devices
• Mice, keyboards, most user interface peripherals
  dont need fast data rate
• Eliminates need for shielded twisted pair cable
  (3 meters)
• Allows use of less-expensive IC process technology

Universal Serial Bus
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USB Connections and Terminations
VCC
R2
D
D
F.S./L.S. USB Transceiver
F.S. USB Transceiver
R1
Twisted Pair Shielded
D-
D-
(45??Outputs)
ZO 90?15 5 Meters Max.
(45??Outputs)
GND
Hub Port 0 or Full Speed Function
R1
Host or Hub Port
R1 15K?5 R2 1.5K?5
GND
D
D
F.S./L.S. USB Transceiver
L.S. USB Transceiver
VCC
R1
Untwisted, Unshielded
R2
D-
(45??Outputs)
3 Meters Max.
(45??Outputs)
GND
D-
R1 15K?5 R2 1.5K?5
R1
Host or Hub Port
Low Speed Function
GND
Universal Serial Bus
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Transfer - Transaction - Packet (1)

• Host Software initiates Transfer from or to a
  target USB Device
• Host software splits up one Transfer into one or
  more Transactions
• Transactions are set up based on the Device's
  characteristics (Packet Size, Transfer Type)

Universal Serial Bus, details
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Transfer - Transaction - Packet (2)

• Host Software schedules and executes Transactions
  during 1ms Frames
• Each Frame consists of several Transactions from
  different Transfers

Universal Serial Bus, details
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Transfer - Transaction - Packet (3)

• Each Transaction consists of a series of packets
• Token Packet defines the Type of Transaction
• Data Packet carries the payload to or from a
  Device
• Handshake Packet provides feedback about correct
  data transfer to sender

Universal Serial Bus, details
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Packet Formats
Token Packet
SOF Token Packet
Data Packet
Handshake/
Low Speed Preamble
Universal Serial Bus, details
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IN Transaction without errors

• Token Packet defines the direction of the
  succeding Data Packet (here IN Data Packet
  from Device to Host)
• Data Packet carries the payload
• Handshake Packet reports error free reception of
  Data Packet

Universal Serial Bus, details
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Low Speed - Full Speed Transaction

• Protocol overhead for FS and LS Transfers is 13
  bytes
• Payload for FS and LS is 8 bytes
• FS Transfer
• 13 8 21 full speed bytes times
• LS Transfer
• 13 8 8 8 168 full speed byte times
  (excluding Preamble)
• 9,5 of bandwidth wasted

Universal Serial Bus, details
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USB 2.0 Technical Overview

• Brad Hosler
• USB Engineering Manager
• Intel Corporation

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Conference Goal

• Provide you with the information youneed to
  build USB 2.0 products
• USB 2.0 technical details
• USB 2.0 Infrastructure
• Building USB 2.0 devices
• USB 2.0 Building Blocks

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USB 2.0 Conference Agenda
Single TrackTopics for Everyone

• Architecture Overview
• Peripheral Development Enabling
• USB 2.0 Compliance and Logo Program
• USB 2.0 Compliance Testing

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USB 2.0 Technical Agenda
Split Track Focused Topics

• USB2 Specifications
• Electricals
• Protocol
• Hubs
• Power Management
• Host Controller Spec
• Cable Testing
• USB On the Go

• USB2 Software
• MS Roadmap
• Driver Testing
• HS Isoch Interface
• Building USB2 Devices
• Design Options
• Transceiver Macrocell
• Firmware and Testing
• Analyzers
• Platform Design
• BIOS

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ArchitectureOverview
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USB 2.0 What Changed??

• Low level electricals for High Speed (HS)
  signaling
• Much higher bit rate (480Mb/s) requires new
  transmitter/receiver
• Hub changes for backward compatibility
• Features limit bandwidth impact of Full Speed
  (FS)and Low Speed (LS) devices on HS devices
• FS/LS devices consume a bit-rate equivalentof HS
  bandwidth

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USB 2.0 What Didnt Change?

• Same host/device model
• Host is in charge
• Devices are inexpensive
• Same basic protocol
• Token, data, handshake
• Same device framework
• Descriptors
• Same software interfaces
• USBDI

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USB 2.0 What Didnt Change?
Continued

• Same power distribution and consumption
• 500ua suspend, 100ma unconfigured,500ma
  configured
• Same power management features
• Suspend/resume model unchanged
• Same topology management
• Hub features to handle connect,
  disconnect,enable, disable,
• Same cables and connectors

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Sample USB 2.0 Topology

• Hub provides high-speed expansion (ala USB 1.1
  hub)
• Hub provides additional Full/Low speed bus(es)

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USB 2.0 Host Controller

• Allows port functionality regardless of OS
  version
• USB 1.1 OS will just work as USB 1.1 ports
• USB 1.1 HCs can go away over time
• Replaced with integrated USB 2.0 Hub

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USB 2.0 Hub
High Speed only
Hub Controller
Transaction Translator
HS Signal Repeater
Routing Logic
Full/Low Speed
Port
Port
Port
Port

• Hub controller same as USB1.1
• Routing logic connects device to appropriate path

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Transaction Translator (TT)

• TT handles low/full speed transactions
• Driven with split transactions
• Start-Split
• Host tells Hub to initiate full/low speed
  transaction
• Complete-Split
• Host asks Hub for results of previous
  full/lowspeed transaction

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Bandwidth Usage

• Low/full speed devices use bit-rate equivalent of
  USB2.0 bandwidth
• 6Mbps classic camera (50 of classic) uses less
  than 2 of USB2.0 bandwidth (6Mbps/480Mbps)

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ISOCH IN Through a TT
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Demo Full Speed Device

• Show the split transactions
• Show better performance behind USB 2.0hub than
  behind USB 1.1 HC

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Summary

• Two major changes for USB 2.0
• Higher speed electricals
• Transaction translator in USB2.0 hub
• Backward compatibility
• Has little impact on HS bandwidth
• May even improve FS performance