USB Universal Serial Bus

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USB
??? ??? ????????? ??????
43650035 ?????? ????? ????????
43650167 ?????? ????????? ????????? 43650332
???? 204521 Digital System Architecture
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?????????? USB (Universal Serial Bus) (1)

• Universal Serial Bus ?????????????????? 1995
  ??????????????????? Compaq, Hewlett Packard,
  Intel, Lucent, Microsoft, NEC ??? Philip
• ??????????????????????????????????????????????????
  ???????????????? PC ??????????????????????
  ??????????????????????????????????????????????????
  ?????????????????????????????????????
• ?????????? ????????????
• ??????????????? 100 ????????????????? serial port
  
• ???????????????????????????????? ??? ????
  printer scanner

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System Resources Used by Legacy Pheripheral
Devices
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????????????????????????? USB

• ?????????????????
• ?????????????????? conflict ??? resource
• ??????????????????????????????????
• Plug and play support
• hot attachment

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Table 2-1 Application,Relative Performance
Required and Desired Attributes
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Various Solutions with Relative Performance and
Complexity
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USB System Implement in a PCI-based Platform
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The primary hardware and software in USB

• USB Hardware
• USB Host Controller/Root Hub
• USB Hubs
• USB Devices
• -USB Software
• USB Device Drivers
• USB Driver
• Host Controller Driver

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Communication Flow in a USB System
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USB Host Controller/Root Hub
Read
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The root hub

• Provide the connection points for USB devices and
  this operations
• Control power to its USB ports
• Enables and disable ports
• recognizes devices attached to each ports
• sets and report status events

• Root hub consists of
• A hub controller
• repeater

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Block Diagram of Major Root hub Functions
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USB Hub Types
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Primary hub Functions
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Hub Repeater
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Communication Flow

• USB Client
• USB Driver
• Host Controller Driver
• Host Controller
• Hub
• Device

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USB Driver

• Provides interface and services for client
  software drivers, allocate bus bandwidth, and
  manages configuration process

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Host Controller Driver

• Controls operation of the host controller,
  schedules transactions and monitors completion
  status of transactions

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Communication Flow
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Transfers

• Transfer type
• Isochronous Transfers
• Bulk Transfers
• Interrupt Transfers
• Control Transfer

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Frames

• USB communication is based on transferring data
  at regular (1ms) intervals call Frames
• Each USB device requires a portion of the USB
  bandwidth be allocated during these 1ms frames

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Frame Example
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Device Framework

• USB Bus Interface Layer represent the actual
  transfer of data across the USB cable between the
  host system and USB device
• USB Device Layer represent the portion of USB
  that comprehends the actual USB communication
  mechanism and the nature of transfers required by
  USB functional device.
• Function Layer represents the relationship
  between client software and a given devices
  functional interface

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Device Framework
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?????????? USB (Universal Serial Bus) (2)

• USB 1.1 ?????????????????????
• USB 2.0 ??????????????????????????????????????????
  ?????

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??????????????? USB ???? 1.1

• ???????? system software
• ??????????????????????? IO system ??????
  ????????????????? ????????????????????????????????
  ?????????????????????
• ??? ????????? USB ????????????????????????????????
  ?????? USB ?????????????????????? ??????????
  load ??? device driver ???????????????

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??????????????? USB ???? 1.1

• ???????? hub
• ???????????????????????? ??????? USB
• hub ????????????????????? ???????????????????????
  ????????????????????????????????????????????? 0.5
  W ?????????? USB 1??? ??????????????????Host
  PC software , hub ??????????????????????? ??????
  2.5 W
• ???????? hub ????????????????? Bi-Directional
  Repeater ?????????? USB signal
  ????????????????????? ???? ??? host ????????? ???
  ?????????? ?? host
• hub ?????? ????????? ?????? ??? full speed
  ??????????? 12 Mbs ??? lowspeed ??????? 1.5 Mbs

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??????????????? USB ???? 1.1

• ??????????????? ??? USB
• ???????????????????? host PC ???????????
  ????????? ???????????? host PC ????????????????
  ??????????????? ??????????????????? USB Data ,
  ??????? USB 1.1 ????????????????????????? ?????
  12 Mb/s ???? ??? 1.5 Mb/s

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?????????????? USB 2.0

• ???????? system software
• ?????????????????????????? USB 1.1 ?????? system
  software ?????????????????????????????????????
  USB 2.0 ?????????????????????????????????????????
  ???????????? ??????? USB 2.0 ?????????????????????
  ??????????????????

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?????????????? USB 2.0

• ???????? USB 2.0 hub
• ????????? high speed ?????????????????????????????
  ??? ??????? USB 2.0 ??? ???????? USB 1.0
  ?????????????? ??????????????? hub
  ???????????????????? ??? ?????? buffer
  ??????????????????? ??????????????
  ????????????????????? high speed
• ????????????? ??????????????? ??? ??????? USB
  2.0 , hub ??? USB 2.0 ????????????????????? high
  speed ????????????? USB 2.0 ???????????????????
  ? ??????? USB 1.1 , hub USB 2.0 ??????????????
  ?????????????????? ??????????? ???????????????????
  ???????????????????????????? ??????????????? hub
  ?????????????????????????????? host ??????? high
  speed ???????????? low speed??????????????????????
  ???????????????? ??????? USB 1.1

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?????????????? USB 2.0

• ??????????????? ??? USB
• ??????????????????????????????????????????????????
  ?????? USB 2.0 ???? ?????????????????????????????
  ?????? ?????? ????????? ????? , ????????? ,
  ??????? ?????????????????????????????? ??? USB
  2.0 ??????? USB 1.1 ?????????????
  ??????????????????? ???? ?????? ????????????
  ??????? ?????????????????????????????

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???????????????? USB ??? ?????????????
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The End.