What is USB?

1
What is USB?

• Circuit Design Unit

2
What is USB?

• USB stands for Universal Serial Bus
• and is the next step in creating a computer
  interface that really works universally.
• It boasts cross-platform compatibility for
  Macintosh, Linux/UNIX operating systems, and all
  versions of Windows since 98SE.
• The USB connector ports are available standard on
  virtually every computing machine manufactured in
  the past decade.

3
Why use USB?

• USB is the first cross-platform hot-swappable
  interface- no more operating system
  incompatibility, no more restarting before
  unplugging or plugging in.

4
What are the types of connectors?

• For the most part, there are four types of
  connectors on USB cables a long, flat rectangle
  for plugging into computers and hubs called
  'USB-A',
• and 'USB-B, a smaller, square connector for
  plugging into devices like external CD and Hard
  drives, scanners, and printers.

5
What are the types of connectors?

• Next is the miniUSB and then the newest the
  microUSB. These types of USB connectors are
  found on cell phone, cameras, microprocessing
  boards (RaspberryPi, Arduino).

6
How USB Works an Overview

• USB uses a four or five-wire cable interface.
• Two of the wires are used in a differential mode
  for both transmitting and receiving data, two
  wires are power and ground and the remaining wire
  is used to id the device.
• The source of the power to a USB device can come
  from the host, a hub, or the device can be "self
  powered.
• There are two different connector types on each
  end of a USB cable. One of these connectors is
  for upstream communications, and the other for
  downstream. Each cable length is limited to about
  5 meters.

7
How USB Works an Overview

• USB has four types of communication transfer
  modes
• control,
• interrupt,
• bulk, and
• isochronous.
• Control mode
• is initiated by the host. In this mode, every
  data transfer must send data in both directions,
  but only in one direction at a time. The control
  mode is used mainly for initialization of
  devices, but it can also be used to transfer
  small amounts of data.
• In interrupt mode, interrupts do not occur in the
  usual sense. As in control mode, the host has to
  initiate the transfer of data. Interrupt mode
  works by the host querying devices to see if they
  need to be serviced.
• Bulk mode and isochronous mode complement each
  other in a sense.
• Bulk mode is used when data accuracy is of prime
  importance, but the rate of data transfer is not
  guaranteed. An example of this would be disk
  drive storage.
• Isochronous mode sacrifices data accuracy in
  favor of guaranteed timing of data delivery. An
  example of this would be USB audio speakers.

8
USB Wiring Warning!

• Improperly wiring a USB port can result in
  permanent and fatal damage to the computer
  motherboard, the USB port and ANY peripheral
  connected to the motherboard.
• It is imperative that the specific USB pin out
  assignment is identified before any attempt is
  made to connect the cable to the motherboard. 
• Simply knowing which pin is 1 is not enough
  information to properly wire a USB port. 
• Trial and error will surely result in the
  destruction of the computer motherboard, the
  computer system and/or any attached peripheral. 

9
USB A Pinouts
Pin Name Color Notes
1 VBUS Red Power
2 D- White Data -
3 D Green Data
4 GND Black Ground
10
USB B Pinouts
Pin Name Color Notes
1 VBUS Red Power
2 D- White Data -
3 D Green Data
4 GND Black Ground
11
USB Micro Pinouts
12
USB Mini Pinouts
13
USB Voltage

• Supplied voltage by a host computer, or a powered
  hub port is between 4.75 and 5.25 Volts of
  Direct Current (DC).
• Maximum voltage drop for bus-powered hubs is 0.35
  V from it's computer host, or hub, to the hubs
  output port.
• Normal operational voltage for USB circuits is a
  minimum of 4.75 Volts DC.

14
USB 3.0

• WHY USB 3.0?
• USB 3.0, also known as SuperSpeed USB, is the
  next evolutionary phase of the Universal Serial
  Bus, inarguably the most successful interface
  standard.
• As computer hardware and peripherals continue to
  expand in capacity, speed, and portability, the
  interfaces that connect them must also advance in
  these areas.

15
USB 3.0- A
Certainly the most recognizable form in computing
today, the USB A connector remains largely
unchanged from the 2.0 specification to the
SuperSpeed 3.0.
16
USB 3.0- B

• Unlike the host-connector A type, the device-end
  connector of the USB world receives a physical
  upgrade in the 3.0 specification.
• The SuperSpeed USB B port is similar to the
  square-ish USB B of the past, but with an
  additional level protruding from the top of the
  connector.
• This added area contains the five additional pins
  used for SuperSpeed data transfers.

17
USB 3.0- Micro

• The SuperSpeed standard makes a noble attempt to
  provide a new functionality to USB devices, but
  will undoubtedly stir up plenty of confusion with
  its Micro-A and Micro-B connectors.
• The underlying principle is that some USB
  products, including smartphones and tablets,
  should be able to function not only as devices
  (connecting to a desktop computer) but also as
  hosts (connecting to a printer, keyboard, or
  camera).
• To do this, a miniature connector set ("Micro")
  was designed to be cross-compatible with both
  host ("A") and device ("B") connectors