USB Universal Serial Bus

1
USB (Universal Serial Bus)
2

• Provides a serial bus standard for connecting
  devices, usually to computers (PCs Apple
  Macintosh) but is also becoming commonplace on
  video games consoles and devices like TVs and
  home Stereo equipment.

3
Brief History

• USB 1.0 (1996) supported 1.5 Mb/ps-12 Mb/ps was
  created to replace serial parallel connections.
• USB 1.1 (1998).
• USB 2.0 (2000) 480 Mb/ps
• USB OTG (2002) enables portable USB devices to be
  cabled directly together without the need for a
  PC.
• Wireless USB based on the ultra wideband (UWB)
  technology which supports the same 480 Mbps data
  rate over a distance of two meters (about 6.6
  feet).

4
Characteristics

• It uses a much higher data transfer rate than
  many common serial data formats.
• The computer acts as a host.
• Up to 127 devices can connect to the host.
• USB cables can run as long as 5 meters.
• Hot-swappable" operation (you can safely plug
  and unplug devices without turning off the
  devices or the computer)
• "Plug 'n' Play" you can attach a new peripheral
  to a computer and have it work immediately,
  without puzzling over cryptic installation
  manuals or restarting the computer multiple
  times.

5

• There are two wires of power - 5 volts (red)
  and ground (brown).
• - Twisted pair (yellow and blue) of wires to
  carry the data.

6
USB PROCESS

• When host Powers up, it queries all of devices
  connected to the bus and assign each one an
  address. (Enumeration)
• CONTROL (Host) data is send in both directions ,
  one direction at a time. Initialization.
• INTERRUPT mouse or keyboard (little data) would
  choose the interrupt mode.
• BULK printer receives data in one big packet.
  The block of data is sent to the printer (64-byte
  chunk) and verified to make sure it is correct.
• ISOCHRONOUS streaming device (speakers) data
  streams in real time, no error correction.

7

• A USB hub provides additional ports for the user
• The USB ports on computers and hubs have a
  rectangular Type A socket, and peripheral devices
  have a cable with a Type A plug. Peripherals that
  do not have an attached cable have a square Type
  B socket on the device and a separate cable with
  a Type A and Type B plug.
• The Mini-A and Mini-B connectors are used on
  small portable devices such as PDAs, music
  players, digital cameras and cellphones.

8
(No Transcript)
9
(No Transcript)
10
TRANSFER SPEED

• A Low Speed rate of 1.5 Mb/s that is mostly used
  for Human Interface Devices (HID) such as
  keyboards, mice and joysticks.
• A Full Speed rate of 12 Mb/s . Full Speed was the
  fastest rate before the USB 2.0 specification and
  many devices fall back to Full Speed. Full Speed
  devices divide the USB bandwidth between them in
  a first-come first-served basis and it is not
  uncommon to run out of bandwidth with several
  isochronous devices. All USB Hubs support Full
  Speed.
• A Hi-Speed rate of 480 Mbit/sc .

11
Technical differences between Fire Wire and USB

• USB networks use a star topology, while FireWire
  networks use a repeater-based topology.
• USB uses a "speak-when-spoken-to" protocol
  peripherals cannot communicate with the host
  unless the host specifically requests
  communication. A FireWire device can communicate
  with any other node at any time, subject to
  network conditions.
• A USB network relies on a single host at the top
  of the tree to control the network. In a FireWire
  network, any capable node can control the
  network.