peripheral ports

Peripheral Ports

Submitted by:- Submitted to:-Alekh M Sharma Mr. M.S.Narkhede(132503)

Peripheral Ports

Contents:-

USB Ports

Fire Wire

IRDA

USB Ports• History:-In 1995 three drawbacks of legacy serial ports nagged at PC developers.These drawbacks are:-• They were slow• Fraught with interconnection difficulties• Allow only one device for every port connector on the back of the PCTo overcome these drawbacks Compaq, Digital Equipment Corporation (DEC),

IBM, Intel, Microsoft and NEC, joined later by Hewlett-Packard, Lucent and, Philips got together and designed the USB .

Later that year, they started the USB Implementers Forum and in1996 unveiled the new interface to the world.

USB PortsHow they overcome these drawbacks:-• To improve performance , it boasted a 12 mbits/sec data rate.• To improve wiring hassle they developed a strict wiring system with

exactly one type of cables to serve all interconnection needs.• To allow one jack on the back of a PC to handle as many peripherals as

necessary, they designed the system to accommodate upto 127 devices per port.

In addition to this they built in plug-and-play support so that every connection is self configuring. You could even hot-plug new devices and use them without reloading your operating system.

USB Ports• Background:-• USB is the substitution of software intelligence for cabling confusion.(i.e.

USB handles all the issues involved in linking multiple devices with different capabilities and data rates with a layer cake of software.)

• USB divides serial hardware into two classes:– hubs :- A USB hub provides jacks into which you can plug functions– functions:- A USB function is a device that actually does something

USB designers imagined that a function may be anything that you can connect to your computer, including keyboard ,mice , modems, printers, plotters, scanners, or whatever.

• Rather than a simple point-to-point port, the USB acts as an actual bus that allows you to connect multiple peripherals to one jack on your pc with all the linked devices sharing exactly the same signals.

• Information passes across the bus in the form of packets, and all functions receive all packets.

USB Ports• Computer accesses individual functions by adding a specific address to the

packets, and only the function with the correct address acts on the packets addressed to it.

• When you need more devices to add to your PC, you add HUB which offers multiple jacks to let you plug in several devices. You can plug one hub into another to provide several additional jacks and ports to connect more devices.

• Your PC acts as a base hub for a USB system and is termed as HOST.• The circuitry in your PC which controls this integral hub and the rest of the

USB system is called the BUS CONTROLLER. Each USB system has has one and only one bus controller.

• All the system requires is that you properly plug everything following its simple rule-each device must plug into a hub and the USB software sorts everything out. This software, making up the USB PROTOCOL, is the most complex part of the design.

USB Ports

USB Ports• The protocol limits the number of functions on one bus to 127 because of

addressing limits. Seven bits are allowed for encoding function addresses, and one of the potential 128 is reserved.

• The record number of devices connected to a single USB port is 101, made in a demonstration at Intel’s Developer’s Forum on September 14, 1998.

• CONNECTORS:-• The USB system involves four different styles of connectors:-o Two chasis mounted jacks.o Two plugs in the end of the cable.Each jack and plugs come in two varieties A and B.Hubs have A jacks. These are the primary out ward manifestation of USB port-

the wide-thin USB slot you find on the back of your PC.All USB cables will have an A plug at one end and a B plug at other. One end

must attach to the hub and other to the device.All A jacks are output and all B jacks are inputs.

USB PortsHubs have A jacks. These are the primary out ward manifestation of USB port-

the wide-thin USB slot you find on the back of your PC.All USB cables will have an A plug at one end and a B plug at other. One end

must attach to the hub and other to the device.All A jacks are output and all B jacks are inputs.

• USB CABLES:-The physical USB wiring uses a special 4 wire cables.Two conductors in the cable transfers the data as a differential digital signal.The USB cable includes a power signal, nominally 5v’s DC and a ground

return.

USB PortsThe individual wire’s in the USB cables are color-coded. The digital signals

form a green and white pair, + data signal on green.The positive 5v’s signal rides on red wire and the ground wire is black.

USB Cable Color Code

USB Ports

• Evolution:-• USB 1.0 specification introduced in 1994• USB 2.0 specification finalized in 2001• Became popular due to cost/benefit advantage

Eg. IEEE 1394 – high bandwidth, high cost• Three generations of USB

• USB 1.0(1.5Mbps)• USB 2.0(480Mbps )• USB 3.0 (5 Gbps ) • Wireless USB 480 Mbps (at 3 m) or 110 Mbps (at 10 m)

Fire wire• It is also known as I. Link, DV, IEEE-1394.• It is a serial interface that’s aimed at high throughput devices.• Originally it is conceived as a general-purpose interface suitable for

replacing legacy serial ports but with blazing speed.• It appeared destined for the same application as USB , however, the

interface is repositioned to complement USB. Where USB takes the low road, IEEE-1394 takes the high speed route.

• Fire wire is a hardware interface, it specifies speeds, timing and a connection system and the software side is based on SCSI.

• Fire wire initiated by Apple and the IEEE in the late 80s. • Transmitted originally at 400Mbps• Used to have a patent of 25 cents charged to any computer that used it;

and needed hardware to run it that cost 1-2 dollars This may have caused it’s demise?

Fire wirePerformance:-

Fire wire

• Currently there are three main standards and hundreds of IEEE recommendations.

• For an idea of the enormity of the field check the IEEE website: http://www.1394ta.org/Technology/Specifications/specifications.htm

• Three standards:– IEEE 1394

• Original Standard, release in 1995• Supports transfer rates of 100,200,400Mbps

– IEEE 1394a • Fixed interoperability problems that were left out of the spec for IEEE 1394• Added performance enhancements into the spec over the original

– IEEE 1394b• Enhanced transfer rates for 800 , 1600, 3200Mbps• Separated the Standard from the Protocol• Provides long-haul transmission while offering backward compatibility

Standards:-

http://www.1394ta.org/Technology/Specifications/specifications.htm

Fire wire

• Cable And Connection:-• Two power conductors in the cable can supply power (8 to 30 volts, 1.5

amps maximum) from the computer to an unpowered device. • Two twisted pair sets carry the data in a FireWire 400 cable using a 6-pin

configuration. • Some smaller FireWire-enabled devices use 4-pin connectors to save

space, omitting the two pins used to supply power.

Fire wire

• Connector (1394a)

Fire wire• FireWire 800 cables use a 9-pin configuration. Six of those pins are the

same as the six pins in the 1394a connector .• Two of the added pins provide a "grounded shield" to protect the other

wires from interference, and the third added pin does nothing at this time.

Fire wire

Fire wire• Here's a summary: -

FEATURE USB FIREWIREVersions 2.0 800Data transfer rate 480 Mbps 800 MbpsNumber of devices 127 63Plug and play Yes YesHot-pluggable Yes YesBus power Yes YesBus type Serial Serial

Cable type Twisted pair (4 wires: 2 power, 1 twisted-pair set)

Twisted pair (8 wires: 2 power, 2 twisted-pair sets, 2 ground)

Networkable Yes - host-based Yes - peer-to-peerNetwork topology Hub Daisy chain

IrDA• Infrared Developers Association (IrDA), this group aimed at more than

making computer more convenient to carry.• The idea behind the get together was to create a standard for using

infrared light to link your computer to peripherals and other systems.• Infrared light is invisible electromagnetic radiation that has a wavelength

longer than that of visible light.• IrDA specifies that the infrared signal used by computers for

communication has a wavelength between 850 and 900 angstroms.• All IrDA ports must be able to operate at one basic speed—9600 bits per

second. All other speeds are optional.

IrDA• The infrared cell of an IrDA transmitter sends out its data in pulses, each

lasting only a fraction of the basic clock period or bit-cell. • The relatively wide spacing between pulses makes each pulse easier for

the optical receiver to distinguish.• Depending on the speed at which a link operates, it may use one of two

forms of modulation. At speeds lower than 4.0Mbps, the system employs Return-to-Zero Invert (RZI) modulation.

• At the 4.0Mbps data rate, the IrDA system shifts to pulse position modulation. Because the IrDA system involves four discrete pulse positions, it is abbreviated 4PPM.

IrDA

Signaling Rate Modulation Pulse Duration2.4Kbps RZI 78.13 microseconds

9.6Kbps RZI 19.53 microseconds





0.576Mbps RZI 434.0 nanoseconds

1.152Mbps RZI 217.0 nanoseconds

4.0Mbps 4PPM, single pulse 125 nanoseconds

4.0Mbps 4PPM, double pulse 250.0 nanoseconds

IrDA Speeds and Modulation

IrDA• IrDA Format:-• The IrDA system doesn't deal with data at the bit or byte level but

instead arranges the data transmitted through it in the form of packets, which the IrDA specification also terms frames.

• A single frame can stretch from 5 to 2050 bytes (and sometimes more) in length.

• An IrDA frame includes address information, data, and error correction.

• Whenever a receiver detects a string of seven or more consecutive logical ones—that is, an absence of optical pulses—it immediately terminates the frame in progress and disregards the data it received

Thank You

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