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The Complete Guide on USB |
If you need to ad more devicies to your system, but find your out of IRQs ... consider USB components and peripherals.
If your system doesn't have USB ports installed, check your motherboard manual. You may be able to install a USB port to your motherboard fairly cheap. $10.00 to $25.00
USB components and peripherals are a tad more expensive, but you get more with USB. Faster information exchange is the primary bonus. Instead of transmitting information one character or byte at a time, USB components transfer pre-determined sizes of packets of information that are typically 8, 16, 32 or 64 bytes in size. USB also provides the ability to add on seemingly endless numbers of USB components, up to 127!
OK, let's look at USB:
Short for Universal Serial Bus, a new external bus standard that supports data transfer rates of 12 Mbps (12 million bits per second). A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. USB also supports Plug-and-Play installation and hot plugging.
iMac is mostly responsible for the way USB that USB became widespread in 1998. It is expected to completely replace serial and parallel ports.
Take a look at these USB sites for more extensive information:
USB Frequently Asked Questions
http://www.usb.org/developers/usbfaq.html
Welcome to USBnews
http://www.usbnews.com/
USB Workshop -- Bring USB into focus
http://www.usbworkshop.com/
USB Host/Device Exerciser
http://www.transdimension.com/exerciser.htm
USB Product News and Iinformation
http://www.allUSB.com/
Welcome to the home of the Linux USB Project
http://www.linux-usb.org/
Intel 8x930 and 8x931 USB Peripheral Controllers
http://www.intel.com/design/usb/
Universal Serial Bus Technology
http://www.microsoft.com/hwdev/usb/
Shows the following:
USB provides an expandable, hot-pluggable Plug and Play serial interface that ensures a standard, low-cost socket for adding external peripheral devices. These devices range from interactive HID devices such as joysticks and pointing devices to isochronous devices such as telephony, audio, and imaging devices. USB allows cascading hubs that can be integrated into desktop devices such as monitors and keyboards.
USB is supported under Microsoft® Windows® 98 and Windows 2000. Migration to USB is recommended for all I/O devices that use legacy ports.
A USB peripheral that fits into one of the USB device class definitions should comply with the related USB device class specification. USB class drivers and WDM support provided in Windows 98 and Windows 2000 support devices that comply with the particular device class specification. Devices can use the generic class drivers provided with the operating system, or manufacturers can create drivers or WDM minidrivers (depending on the device class) to exploit any additional unique hardware features.
The Categories are:
*Designing USB Handset Peripherals for Windows
*Designing USB Hubs to Ensure a Good User Experience
*FAQ for USB and Windows Drivers
*Handling Asynchronous Bulk Data Transfer in a USB Minidriver (Dr.
Iver)
*Looking at the USB Driver Interface
*Microsoft USB Point-of-Sale
*Platform Compatibility for USB Boot Devices
*Universal Serial Bus and Game Devices
*USB Plug and Play IDs and Selecting Device Drivers to Load
*USB-to-Legacy Mapper Products
*WDM USB Driver Interface
*Windows 98 USB Support
See also:
Human Interface Device (HID) White Papers
USB Video Device White Papers
USB and Peripherals Guide for MAC's
http://www.macintouch.com/imacusb.html
ScanLogic Corporation
"Embedded USB Controller chip solutions for: ATAPI, IDE, HDD, etc"
http://www.scanlogic.com/
Universal Serial Bus Implementers Forum
http://www.usb.org/
Information, tools, and links to material about the Universal Serial
Bus (USB)
Brought to you by Jan Axelson
http://www.lvr.com/usb.htm
USB Designer Links
Contains links to technical information for USB developers.
http://www.ibhdoran.com/usb_link.html
Universal Serial Bus: A Developer Tutorial
http://triton.cc.gatech.edu:8080/ubicomp.112
ACK
Acknowledgment. Handshake packet indicating a positive acknowledgment.
Active Device
A device that is powered and not in the suspend state.
ADB
See Apple Desktop Bus.
APM
An acronym for Advanced Power Management. APM is a specification for
managing suspend and resume operations to conserve power on a host system.
Apple Desktop Bus
An expansion bus used by personal computers manufactured by Apple Computer,
Inc.
Asynchronous Data
Data transferred at irregular intervals with relaxed latency requirements.
Asynchronous RA
The incoming data rate, Fsi, and the outgoing data rate, Fso, of the
RA process are independent (i.e., no shared master clock).
Asynchronous SRC
The incoming sample rate, Fsi, and outgoing sample rate, Fso, of the
SRC process are independent (i.e., no shared master clock).
Audio Device
A device that sources or sinks sampled analog data.
AWG#
The measurement of a wires cross section as defined by the American
Wire Gauge standard.
Babble
Unexpected bus activity that persists beyond a specified point in a
frame.
Bandwidth
The amount of data transmitted per unit of time, typically bits per
second (bps) or bytes per second (Bps).
Big Endian
A method of storing data that places the most significant byte of multiple
byte values at a lower storage addresses. For example, a word stored in
big endian format places the least significant byte at the higher address
and the most significant byte at the lower address. See Little Endian.
Bit
A unit of information used by digital computers. Represents the smallest
piece of addressable memory within a computer. A bit expresses the choice
between two possibilities and is typically represented by a logical one
(1) or zero (0).
Bit Stuffing
Insertion of a Ò0Ó bit into a data stream to cause an
electrical transition on the data wires allowing a PLL to remain locked.
bps
Transmission rate expressed in bits per second.
Bps
Transmission rate expressed in bytes per second.
Buffer
Storage used to compensate for a difference in data rates or time of
occurrence of events, when transmitting data from one device to another.
Bulk Transfer
Nonperiodic, large bursty communication typically used for a transfer
that can use any available bandwidth and also be delayed until bandwidth
is available.
Bus Enumeration
Detecting and identifying Universal Serial Bus devices.
Byte
A data element that is eight bits in size.
Capabilities
Those attributes of a Universal Serial Bus device that are administerable
by the host.
Characteristics
Those qualities of a Universal Serial Bus device that are unchangeable;
for example, the device class is a device characteristic.
CHI
An acronym for Concentration Highway Interface. CHI is a full duplex
time division multiplexed serial interface for digitized voice transfers
in communications systems. The current specification supports data transfer
rates up to 4.096ÊMbs.
Client
Software resident on the host that interacts with host software to
arrange data transfer between a function and the host. The client is often
the data provider and consumer for transferred data.
COM Port
Communications port. On personal computers, an eight-bit asynchronous
serial port is typically used.
Configuring Software
The host software responsible for configuring a Universal Serial Bus
device. This may be a system configurator or software specific to the device.
Control Pipe
Same as a message pipe.
Control Transfer
One of four Universal Serial Bus Transfer Types. Control transfers
support configuration/command/status type communications between client
and function.
CRC
See Cyclic Redundancy Check.
CTI
Computer Telephony Integration.
Cyclic Redundancy Check
A check performed on data to see if an error has occurred in transmitting,
reading, or writing the data. The result of a CRC is typically stored or
transmitted with the checked data. The stored or transmitted result is
compared to a CRC calculated for the data to determine if an error has
occurred.
Default Address
An address defined by the Universal Serial Bus Specification and used
by a Universal Serial Bus device when it is first powered or reset. The
default address is 00h.
Default Pipe
The message pipe created by Universal Serial Bus system software to
pass control and status information between the host and a Universal Serial
Bus deviceÕs Endpoint 0.
Device
A logical or physical entity that performs a function. The actual entity
described depends on the context of the reference. At the lowest level,
device may refer to a single hardware component, as in a memory device.
At a higher level, it may refer to a collection of hardware components
that perform a particular function, such as a Universal Serial Bus interface
device. At an even higher level, device may refer to the function performed
by an entity attached to the Universal Serial Bus; for example, a data/FAX
modem device. Devices may be physical, electrical, addressable, and logical.
When used as a non-specific reference, a Universal Serial Bus device is either a hub or a function.
Device Address
The address of a device on the Universal Serial Bus. The Device Address
is the Default Address when the Universal Serial Bus device is first powered
or reset. Hubs and functions are assigned a unique Device Address by Universal
Serial Bus software.
Device Endpoint
A uniquely identifiable portion of a Universal Serial Bus device that
is the source or sink of information in a communication flow between the
host and device.
Device Resources
Resources provided by Universal Serial Bus devices, such as buffer
space and endpoints. See Host Resources and Universal Serial Bus Resources.
Device Software
Software that is responsible for using a Universal Serial Bus device.
This software may or may not also be responsible for configuring the device
for use.
DMI
An acronym for Desktop Management Interface. A method for managing
host system components developed by the Desktop Management Task Force.
Downstream
The direction of data flow from the host or away from the host. A downstream
port is the port on a hub electrically farthest from the host that generates
downstream data traffic from the hub. Downstream ports receive upstream
data traffic.
Driver
When referring to hardware, an I/O pad that drives an external load.
When referring to software, a program responsible for interfacing to a
hardware device; that is, a device driver.
DWORD
Double word. A data element that is 2 words, 4 bytes, or 32 bits in
size.
Dynamic Insertion and Removal
The ability to attach and remove devices while the host is in operation.
EEPROM
Electrically Erasable Programmable Read Only Memory. Non-volatile rewritable
memory storage technology.
End User
The user of a host.
Endpoint
See Device Endpoint.
Endpoint Address
The combination of a Device Address and an Endpoint Number on a Universal
Serial Bus device.
Endpoint Number
A unique pipe endpoint on a Universal Serial Bus device.
EOF1
End of frame timing point #1. Used by the hub to monitor and disconnect
bus activity persisting near or past the end of a frame.
EOF2
End of frame timing point #2. Used by hubs to detect bus activity near
the end of frame.
EOP
End of packet.
Fs
See Sample Rate.
False EOP
A spurious, usually noise induced, event that is interpreted by a packet
receiver as an end of packet.
FireWire
Apple ComputerÕs implementation of the IEEE P1394 bus standard.
Frame
The time from the start of one SOF token to the start of the subsequent
SOF token; consists of a series of transactions.
Frame Pattern
A sequence of frames that exhibit a repeating pattern in the number
of samples transmitted per frame. For a 44.1 kHz audio transfer, the frame
pattern could be nine frames containing 44 samples followed by one frame
containing 45 samples.
Full-duplex
Computer data transmission occurring in both directions simultaneously.
Function
A Universal Serial Bus device that provides a capability to the host.
For example, an ISDN connection, a digital microphone, or speakers.
GeoPort
A serial bus developed by Apple Computer, Inc. Current specification
of the GeoPort supports data transfer rates up to 2ÊMbs and provides
point to point connectivity over a radius of 4 ft.
Handshake Packet
A packet that acknowledges or rejects a specific condition. For examples,
see ACK and NACK.
Host
The host computer system where the Universal Serial Bus host controller
is installed. This includes the host hardware platform (CPU, bus, etc.)
and the operating system in use.
Host Controller
The hostÕs Universal Serial Bus interface.
Host Controller Driver
The Universal Serial Bus software layer that abstracts the host controller
hardware. Host Controller Driver provides an SPI for interaction with a
host controller. Host Controller Driver hides the specifics of the host
controller hardware implementation.
Host Resources
Resources provided by the host, such as buffer space and interrupts.
See Device Resources and Universal Serial Bus Resources.
Hub
A Universal Serial Bus device that provides additional connections
to the Universal Serial Bus.
Hub Tier
The level of connect within a USB network topology given as the number
of hubs that that the data has to flow through.
I2C
Acronym for the Inter-Integrated Circuits serial interface. The I2C
interface was invented by Philips Semiconductors.
IEEE P1394
A high performance serial bus. The P1394 is targeted at hard disk and
video peripherals, which may require bus bandwidth in excess of 100ÊMb/s.
The bus protocol supports both isochronous and asynchronous transfers over
the same set of four signal wires.
Industry Standard Architecture
The 8 and/or 16 bit expansion bus for IBM AT or XT compatible computers.
Integrated Services Data Network
An internationally accepted standard for voice, data, and signaling
using public, switched telephone networks. All transmissions are digital
from end-to-end. Includes a standard for out-of-band signaling and delivers
significantly higher bandwidth than POTS.
Interrupt Request
A hardware signal that allows a device to request attention from a
host. The host typically invokes an interrupt service routine to handle
the condition which caused the request.
Interrupt Transfer
One of four Universal Serial Bus Transfer Types. Interrupt transfers
characteristics are small data, non periodic, low frequency, bounded latency,
device initiated communication typically used to notify the host of device
service needs.
ISDN
See Integrated Services Data Network.
Isochronous Data
A stream of data whose timing is implied by its delivery rate.
Isochronous Device
An entity with isochronous endpoints, as defined in the USB specification,
that sources or sinks sampled analog streams or synchronous data streams.
Isochronous Sink Endpoint
An endpoint that is capable of consuming an isochronous data stream.
Isochronous Source Endpoint
An endpoint that is capable of producing an isochronous data stream.
Isochronous Transfer
One of four Universal Serial Bus Transfer Types. Isochronous transfers
are used when working with isochronous data. Isochronous transfers provide
periodic, continuous communication between host and device.
Jitter
A tendency toward lack of synchronization caused by mechanical or electrical
changes. More specifically, the phase shift of digital pulses over a transmission
medium.
kbs
Transmission rate expressed in kilobits per second.
kBs
Transmission rate expressed in kilobytes per second.
Line Printer Port
A port used to access a printer. On most personal computers, an eight-bit
parallel interface is typically used.
Little Endian
Method of storing data that places the least significant byte of multiple
byte values at lower storage addresses. For example, a word stored in little
endian format places the least significant byte at the lower address and
the most significant byte at the next address.
Big Endian
Refers to which bytes are most significant in multi-byte data types.
In big-endian architectures, the leftmost bytes (those with a lower address)
are most significant. In little-endian architectures, the rightmost bytes
are most significant. For example, consider the number 1025 (2 to the tenth
power plus one) stored in a 4-byte integer.
LOA
Loss of bus activity characterized by a start of packet without a corresponding
end of packet.
LPT Port
See Line Printer Port.
LSB
Least Significant Bit.
Mbs
Transmission rate expressed in megabits per second.
MBs
Transmission rate expressed in megabytes per second.
Message Pipe
A pipe that transfers data using a request/data/status paradigm. The
data has an imposed structure which allows requests to be reliably identified
and communicated.
Micro Channel Architecture
A 32 bit expansion bus used on some IBM PS/2 compatible computers.
Modem
An acronym for Modulator/Demodulator. Component that converts signals
between analog and digital. Typically used to send digital information
from a computer over a telephone network which is usually analog.
MSB
Most Significant Bit.
NACK
Negative Acknowledgment. Handshake packet indicating a negative acknowledgment.
Non Return to Zero Invert
A method of encoding serial data in which ones and zeroes are represented
by opposite and alternating high and low voltages where there is no return
to zero (reference) voltage between encoded bits. Eliminates the need for
clock pulses.
NRZI
See Non Return to Zero Invert.
Object
Host software or data structure representing a Universal Serial Bus
entity.
Packet
A bundle of data organized in a group for transmission. Packets typically
contain three elements: control information (e.g., source, destination,
and length), the data to be transferred, and error detection and correction
bits.
Packet Buffer
The logical buffer used by a Universal Serial Bus device for sending
or receiving a single packet. This determines the maximum packet size the
device can send or receive.
Packet ID
A field in a Universal Serial Bus packet that indicates the type of
packet, and by inference the format of the packet and the type of error
detection applied to the packet.
PBX
See Private Branch eXchange.
PCI
See Peripheral Component Interconnect.
PCMCIA
See Personal Computer Memory Card Industry Association.
Peripheral Component Interconnect
A 32- or 64-bit, processor independent, expansion bus used on personal
computers.
Personal Computer Memory Card International Association
The organization that standardizes and promotes PC Card technology.
Phase
A token, data, or handshake packet; a transaction has three phases.
Physical Device
A device that has a physical implementation; e.g. speakers, microphones,
and CD players.
Pipe
A logical abstraction representing the association between an endpoint
on a device and software on the host. A pipe has several attributes; for
example, a pipe may transfer data as streams (Stream Pipe) or messages
(Message Pipe).
Plain Old Telephone Service
Basic service supplying standard single line telephones, telephone
lines, and access to public switched networks.
Plug and Play
A technology for configuring I/O devices to use non-conflicting resources
in a host. Resources managed by Plug and Play include I/O address ranges,
memory address ranges, IRQs, and DMA channels.
Polling
Asking multiple devices, one at a time, if they have any data to transmit.
Port
Point of access to or from a system or circuit. For Universal Serial
Bus, the point where a Universal Serial Bus device is attached.
Power On Reset
Restoring a storage device, register, or memory to a predetermined
state when power is applied.
PLL
Phase Locked Loop. A circuit that acts as a phase detector to keep
an oscillator in phase with an incoming frequency.
Private Branch eXchange
A privately owned telephone switching system which is not regulated
as part of the public telephone network.
Programmable Data Rate
Either a fixed data rate (single frequency endpoints), a limited number
of data rates (32 kHz, 44.1 kHz, 48 kHz, É), or a continuously programmable
data rate. The exact programming capabilities of an endpoint must be reported
in the appropriate class-specific endpoint descriptors.
Protocol
A specific set of rules, procedures, or conventions relating to format
and timing of data transmission between two devices.
Rate Adaptation
The process by which an incoming data stream, sampled at Fsi is converted
to an outgoing data stream, sampled at Fso with a certain loss of quality,
determined by the rate adaptation algorithm. Error control mechanisms are
required for the process. Fsi and Fso can be different and asynchronous.
Fsi is the input data rate of the RA; Fso is the output data rate of the
RA.
Request
A request made to a Universal Serial Bus device contained within the
data portion of a SETUP packet.
Retire
The action of completing service for a transfer and notifying the appropriate
software client of the completion.
Root Hub
A Universal Serial Bus hub directly attached to the host controller.
This hub is attached to the host; tier 0.
Root Port
The upstream port on a hub.
Sample
The smallest unit of data on which an endpoint operates; a property
of an endpoint.
Sample Rate (Fs)
The number of samples per second, expressed in Hertz.
Sample Rate Conversion
A dedicated implementation of the RA process for use on sampled analog
data streams. The error control mechanism is replaced by interpolating
techniques.
SCSI
Small Computer Systems Interface.
Service
A procedure provided by an SPI.
Service Interval
The period between consecutive requests to a Universal Serial Bus endpoint
to send or receive data.
Service Jitter
The deviation of service delivery from its scheduled delivery time.
Service Rate
The number of services to a given endpoint per unit time.
Small Computer Systems Interface
A local I/O bus that allows peripherals to be attached to a host using
generic system hardware and software.
SOF
An acronym for Start of Frame. The SOF is the first transaction in
each frame. SOF allows endpoints to identify the start of frame and synchronize
internal endpoint clocks to the host.
SRC
See Sample Rate Conversion.
Stage
One part of the sequence composing a control transfer; i.e., the setup
stage, the data stage, and the status stage.
Stream Pipe
A pipe that transfers data as a stream of samples with no defined Universal
Serial Bus structure.
Synchronization Type
A classification that characterizes an isochronous endpointÕs
capability to connect to other isochronous endpoints.
Synchronous RA
The incoming data rate, Fsi, and the outgoing data rate, Fso, of the
RA process are derived from the same master clock. There is a fixed relation
between Fsi and Fso.
Synchronous SRC
The incoming sample rate, Fsi, and outgoing sample rate, Fso, of the
SRC process are derived from the same master clock. There is a fixed relation
between Fsi and Fso.
System Programming Interface
A defined interface to services provided by system software.
TDM
Short for Time Division Multiplexing, a type of multiplexing that combines
data streams by assigning each stream a different time slot in a set. TDM
repeatedly transmits a fixed sequence of time slots over a single transmission
channel. Within T-Carrier systems, such as T-1 and T-3, TDM combines Pulse
Code Modulated (PCM) streams created for each conversation or data stream.
Termination
Passive components attached at the end of cables to prevent signals
from being reflected or echoed.
Time Division Multiplexing
A method of transmitting multiple signals (data, voice, and/or video)
simultaneously over one communications medium by interleaving a piece of
each signal one after another.
Time-out
The detection of a lack of bus activity for some predetermined interval.
Token Packet
A type of packet that identifies what transaction is to be performed
on the bus.
Transaction
The delivery of service to an endpoint; consists of a token packet,
optional data packet, and optional handshake packet. Specific packets are
allowed/required based on the transaction type.
Transfer
One or more bus transactions to move information between a software
client and its function.
Transfer Type
Determines the characteristics of the data flow between a software
client and its function. Four Transfer types are defined: control, interrupt,
bulk, and isochronous.
Turnaround Time
The time a device needs to wait to begin transmitting a packet after
a packet has been received to prevent collisions on Universal Serial Bus.
This time is based on the length and propagation delay characteristics
of the cable and the location of the transmitting device in relation to
other devices on Universal Serial Bus.
Universal Serial Bus
A collection of Universal Serial Bus devices and the software and hardware
that allow them to connect the capabilities provided by functions to the
host.
Universal Serial Bus Interface
The hardware interface between the Universal Serial Bus cable and a
Universal Serial Bus device. This includes the protocol engine required
for all Universal Serial Bus devices to be able to receive and send packets.
Universal Serial Bus Resources
Resources provided by Universal Serial Bus, such as bandwidth and power.
See Device Resources and Host Resources.
Universal Serial Bus Software
The host-based software responsible for managing the interactions between
the host and the attached Universal Serial Bus devices.
Universal Serial Bus Driver
The host resident software entity responsible for providing common
services to clients that are manipulating one or more functions on one
or more Host Controllers.
Upstream
The direction of data flow towards the host. An upstream port is the
port on a device electrically closest to the host that generates upstream
data traffic from the hub. Upstream ports receive downstream data traffic.
Virtual Device
A device that is represented by a software interface layer; e.g., a
hard disk with its associated device driver and client software that makes
it able to reproduce an audio .WAV file.
WFEOF2
Wait for EOF2 point. One of the four hub repeater states.
WFEOP
Wait for end of packet. One of the four hub repeater states.
WFSOF
Wait for start of frame