Electronics World

Clock less Chips

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<b>INTRODUCTION:</b></h3>
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In
labs at Sun Microsystems, Intel and IBM, clock less chips have increased the
pace at which high-end processors do their work. In 1997, Intel developed an
asynchronous, Pentium-compatible test chip that ran three times as fast, on
half the power, as its synchronous equivalent. <o:p></o:p></div>
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 Fant has focused on still another benefit of
asynchronous design. Because these chips give off no regularly timed signal,
the way clocked circuits do, they can perform encryption in a way that is
harder to identify and to crack. Improved encryption makes asynchronous
circuits an obvious choice for smart cards—the chip-endowed plastic cards
beginning to be used for such security-sensitive applications as storage of
medical records, electronic funds exchange and personal identification. . <o:p></o:p></div>
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SMT offers chip designers a big performance
gain for a relatively small design change; asynchronous logic involves a far
more dramatic rethink. As its name suggests, it does away with the cardinal
rule of chip design: that everything marches to the beat of an oscillating
crystal “clock”. For a 1GHz chip, this clock ticks one billion times a second,
and the entire chip’s processing unit’s co-ordinate their actions with these
ticks to ensure that they remain in step. Asynchronous, or “clock less”,
designs, in contrast, allow different bits of a chip to work at different
speeds, sending data to and from each other as and when appropriate.<o:p></o:p></div>
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In recent years,
however, clock less designs have started to look more appealing. One reason is
that, as chips get bigger, faster and more complicated, distributing the clock
signal around the chip becomes harder. Another drawback with clocked designs is
that they waste a lot of energy, since even inactive parts of the chip have to
respond to every clock tick. Clocked chips also produce electromagnetic
emissions at their clock frequency, which can cause radio interference.<o:p></o:p></div>
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Asynchronous
designs take up more room on a chip than conventional designs, and there are
far fewer design tools available to help create them,  It is believes that such chips will have twice
the power of conventional designs, which will make them ideal for use in
high-performance computers. The most promising application for asynchronous
chips may be in mobile wireless devices and smartcards.<o:p></o:p></div>
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One
of the advantages of clock less chips is that they give off very low levels of
electromagnetic noise. The faster the clock, the more difficult it is to
prevent a device from interfering with other devices; dispensing with the clock
all but eliminates this problem. The combination of low noise and low power
consumption makes asynchronous chips a natural choice for mobile devices.
"The low-hanging fruit for clock less chips will be in communications
devices," starting with cell phones. <o:p></o:p></div>
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Wireless devices
based on asynchronous chips would run for longer between recharges, and their
circuitry would cause less radio interference. Dr Furber is developing
asynchronous chips for such devices in conjunction with ARM, a British company
whose processors appear in many handheld computers and mobile phones. Philips,
a Dutch electronics firm, has already built a pager that uses asynchronous
logic, and Theseus Logic of Orlando, Florida, is also pursuing low-power
wireless applications.<o:p></o:p></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 12pt;">In the case of smartcards, Dr Furber suggests
that asynchronous logic would offer better security than conventional chips.
The encryption on existing smartcards can be cracked by analyzing the power
consumption for each clock tick. This allows details of the chip’s inner
workings to be deduced. Such an attack would be far more difficult on a
smartcard based on asynchronous logic.        </span><br />
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<span style="font-family: Times New Roman, serif;"><b>CLOCKLESS CHIPS:</b></span></h3>
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There are no purely
asynchronous chips yet. Instead, today’s clock less processors are actually
clocked processors with asynchronous elements. Clock less elements use <i>perfect
clock gating</i>, in which circuits operate only when they have work to do, not
whenever a clock ticks. Instead of clock-based synchronization, local
handshaking controls the passing of data between logic modules. The
asynchronous processor places the location of the stored data it wants to read
onto the address bus and issues a request for the information. The memory reads
the address off the bus, finds the information, and places it on the data bus.
The memory then acknowledges that it has read the data. Finally, the processor
grabs the information from the data bus. Pipeline controls and FIFO sequencers
move data and instructions around and keep them in the right order. According
to Jorgenson, “Data arrives at any rate and leaves at any rate. When the
arrival rate exceeds the departure rate, the circuit stalls the input until the
output catches up.” The many handshakes themselves require more power than a
clock’s operations. However, clock less systems more than offset this because,
unlike synchronous chips, each circuit uses power only when it performs work.</div>
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<span style="font-family: Garamond, serif;"><span style="font-size: 18.6666660308838px;"><b>CLOCK LESS ARM996HS</b></span></span></div>
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<span style="background-color: white; line-height: 150%; text-align: justify;">The compact, clock less ARM996HS processor is an ideal
solution for automotive, medical and deeply embedded control applications
because of its extremely low power consumption and low Electro Magnetic
Interference (EMI). The ARM996HS processor is the industry’s first licensable clock
less processor and directly addresses the needs of design engineers for
technology optimized for robust and real-time chip designs.</span></div>
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The ARM996HS processor utilizes Handshake Solutions’
technology, a production-proven methodology for implementing self-timed
circuitry which has been used in hundreds of millions of chips for smart cards,
advanced pagers, in-vehicle network transceivers, and cordless handsets. By
leveraging this low EME technology, the ARM996HS processor can address the
market need for very low EMI to reduce packaging and shielding costs.
Additionally, the processor can be used in applications that require low
current consumption and an extended battery life while maintaining real-time
application responsiveness and a small footprint. <o:p></o:p></div>
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By removing the clock and associated architecture of
standard ICs, clock less designs offer significant reductions in power consumption
and EMI enabling designers to squeeze more functionality into limited power
budgets. Handshake Solutions offers an extremely disciplined design methodology
that delivers the unique benefits of clock less design within a commercially
available design environment. The methodology is supported by easy-to-use and
thoroughly field-tested tools, design services, and standard IP blocks from
Handshake Solutions<o:p></o:p></div>
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<span lang="EN">The new ARM996HS processor is
optimized for use in both synchronous (clocked) and asynchronous (clock less)
system-on-chip designs, enabling easy integration by ARM semiconductor
Partners. Engineers can easily design in the new processor using<b> </b>standard cell libraries such as the
ARM Metro family for low power, and their existing EDA tools, for lower costs
and shorter design cycles. The key benefits of the processor include low EMI,
reducing the probability of interfering with sensitive circuitry; low current
peaks, enabling easier integration with analog components; and low power
consumption, reducing system power requirements. Because clock less processors
consume zero dynamic power when there is no activity, they can significantly
extend battery life<o:p></o:p></span></div>
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<span lang="EN" style="font-family: Garamond, serif; font-size: 14pt; line-height: 150%;"><b>FUNCTIONING<o:p></o:p></b></span></div>
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Clock less logic
uses a system of local handshaking rather than a global clock to define
transaction timing. Handshakes are implemented by means of simple request and
acknowledge signals that mark the validity of the data. This approach means
that only those parts of a system actively involved in task execution draw
power, reducing active standby power consumption to zero and extending battery
lifetimes. Execution of individual functions need not wait for the next clock
pulse, enabling immediate response to exceptional events.  Wake-up from interrupt can even be performed
without a running clock. Handshake Solutions’ clock less designs supports
integration with synchronous blocks and systems. This means that the clock less
ARM996HS processor can be easily integrated into a conventional, clocked SoC
design. Because they exhibit no ground bounce, Handshake Solutions functions
can be quickly and easily combined with clocked logic, analog, RF or memory
blocks to meet the exact system requirements.</div>
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<b><span style="font-size: 14.0pt; line-height: 150%;">A COMPLETE CLOCK LESS DESIGN SOLUTION<o:p></o:p></span></b></div>
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Although the
theoretical principles of clock less design are well-defined, implementation of
clock less logic within the context of a complex system design has not,
historically, been straightforward. Potential issues included the availability
of design flow support, the need for special clock less standard-cell
libraries, the area overhead arising from the control logic necessary to
implement the self-timing, and ensuring that clock less designs are testable
using industry-supported techniques.</div>
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Handshake
Solutions has brought clock less technology to a level of maturity where the
technology has now been proven on many designs. With dozens of production
designs incorporating Handshake Technology successfully complete, over a
hundred million Handshake Technology-based ICs have been manufactured, tested
and sold. Developing a rigorous approach has solved the problems that have been
experienced in the practical application of asynchronous technologies in the
past.  </div>
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<span style="line-height: 150%; text-align: justify;">Handshake
Solutions’ offering includes a design flow based on standard cell libraries
with no dedicated asynchronous cells required. The flow is compatible with
standard ‘synchronous’ tools for technology mapping, logic optimization, timing
analysis and testing.</span><span style="line-height: 150%; text-align: justify;">  </span><span style="line-height: 150%; text-align: justify;">A high-level
design entry language called Haste (formerly Tangram), developed specifically
for the specification and designs of clock less circuit, provides the entry
mechanism. Haste, being similar to C and behavioral Verilog, is easy to learn
and use. The design description is synthesized using Handshake Solutions’
silicon compiler. </span><br />
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<span style="line-height: 150%; text-align: justify;">Once the Verilog netlist has been generated, the back-end
design to GDSII can follow any industry-standard implementation flow. This
means that for licensees of the ARM996HS who wish to integrate the processor
into their SoC, it is not necessary to adopt the full Handshake Solutions
design flow, but simply take the Verilog netlist and incorporate it as an IP
block. The methodology also supports scan-test for complete design for test
(DFT) solutions, ensuring that design teams can make use of standard automatic test
pattern generation (ATPG) techniques</span><span style="font-family: 'Times New Roman', serif; font-size: 12pt;"><b> </b>          </span><br />
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The ARM996HS is a new 32-bit RISC processor core –
part of the ARM9E family of cores. The ARM9E family is based on the ARMv5TE
Instruction Set Architecture (ISA), which includes the 16-bit Thumb® and 32-bit
ARM instruction sets. The Harvard-architecture core is based on a 5-stage
integer pipeline with fast 32-bit multiply-accumulate (MAC) block. It has
tightly coupled memories (TCMs) for both instruction and data, each of which
can be up to 4MB. Dual AMBA™ AHB-Lite™ synchronous buses provide the
instruction and data interfaces. Specific security enhancements for the
ARM996HS core include a memory protection unit (MPU) and the provision of
non-maskable interrupts (NMI). A hardware divide co-processor is also provided.</div>
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<b><span style="font-size: 14.0pt;">CLOCK LESS PIPELINE<o:p></o:p></span></b></div>
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The pipeline within the ARM996HS core mirrors the
normal ARMv5TE pipeline, with the exception that it is implemented as a clock
less design. Instead of a global synchronous clock, dedicated control logic
ensures that each stage in the pipeline is enabled only when required. The
pipeline handshakes with the system controller to fetch instructions and to
load and store data.</div>
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<b><span style="font-size: 14.0pt;">ENHANCED MEMORY PROTECTION UNIT<o:p></o:p></span></b></div>
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In order to enable software re-use from several
different sources, it is vital that there is a mechanism to allow each module
to be isolated so that the risk of interference is minimized. The requirement
is to be able to isolate or ‘lock down’ many of these routines. This is
performed by the memory protection unit (MPU). Current Memory Protection Units
(MPUs) typically offer 4KByte code boundaries for isolating functions. This is
typically too large for systems which have limited memory resources. Large code
boundaries mean that it is impossible to efficiently segregate many small
software routines – often several tasks will have to be included within the same
protection scheme.</div>
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To enable good segregation of individual tasks
executed within an operating system (OS) kernel, the ARM996HS MPU provides a
fine 32-byte granularity of memory region for each task. This enables more
effective use of the available memory resource for supporting multiple tasks.
With this level of granularity it is possible to separate: User from system,
task from task, data from data and stack from stack.Shared access is possible
via overlapping regions.</div>
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<b><span style="font-size: 14.0pt; line-height: 150%;">NON-MASKABLE
INTERRUPTS<o:p></o:p></span></b></div>
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Non-Maskable Interrupts (NMI) enables fast interrupt
requests to be made nonmaskable</div>
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by software. Where predictability of execution is
especially important, such as with control applications, NMI is a mandatory
requirement. NMI is particularly important when a watchdog is used in the
system that needs to be serviced at a particular time.</div>
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<b><span style="font-size: 14.0pt; line-height: 150%;">HARDWARE
DIVIDE COPROCESSOR<o:p></o:p></span></b></div>
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For applications where there is a requirement to
scale values read from sensors, the hardware divide instruction enables data to
be manipulated very efficiently. The hardware divide coprocessor provides
efficient implementation of division operations in parallel to the main
processor pipeline. It supports unsigned and signed 32-bit division through
normal coprocessor instructions. The hardware divide coprocessor is easy for
developers to use with tools and library support provided.</div>
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<span style="line-height: 24px;"><b>ADVANTAGES:</b></span></div>
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<span style="line-height: 150%;">Difficulties associated with traditional synchronous design
have prompted many researchers to consider new alternatives. Three factors
drive current research and development efforts in the design and test of clock
less digital systems:</span></div>
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A) Low power</div>
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B) Performance</div>
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C) Design for reuse.</div>
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<b><span style="font-size: 14.0pt; line-height: 150%;">LOW POWER<o:p></o:p></span></b></div>
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The mainstream design style in use for today’s processors
is synchronous, that is, a clock regulates the internal timing. We measure how
fast a computer can execute instructions by the number of clock cycles per second.
Unfortunately, the clock consumes more power than most other components in the
chip. The most disturbing aspect of this characteristic is that the clock only serves
as a timer for computational tasks. It does not perform operations on data, it
simply orchestrates the many computational parts of a digital system (whether
chip, board, or computer). New problems are also evident for power consumption at-large;
that is, throughout the system in general. As the number of transistors on a
chip increases, so does the power used by the clock. Therefore, in complicated chips,
power consumption becomes an even more crucial topic. For mobile and portable
electronics, chips must conserve power even more efficiently to maximize
battery life. Low-power design is important </div>
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Clock less Chips

INTRODUCTION: In labs at Sun Microsystems, Intel and IBM, clock less chips have increased the pace at which high-end processors do their...

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CDMA(Code Division Multiple Access)

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The world is demanding more from wireless communication technologies than ever before. More people around the world are subscribing to wireless services and consumers are using their phones more frequently. Add in exciting Third-Generation (3G) wireless data services and applications - such as wireless email, web, digital picture taking/sending and assisted-GPS position location applications - and wireless networks are asked to do much more than just a few years ago. And these networks will be asked to do more tomorrow.<br />
<br />
This is where CDMA technology fits in. CDMA consistently provides better capacity for voice and data communications than other commercial mobile technologies, allowing more subscribers to connect at any given time, and it is the common platform on which 3G technologies are built.<br />
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CDMA permits a more uniform distribution of energy in the emitted bandwidth Short for Code Division Multiple Access, a digital cellular technology that uses spread-spectrum techniques. Unlike competing systems, such as GSM that use TDMA, CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum. Individual conversations are encoded with a pseudo-random digital sequence.<br />
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CDMA is a "spread spectrum" technology, allowing many users to occupy the same time and frequency allocations in a given band/space. As its name implies, CDMA assigns unique codes to each communication to differentiate it from others in the same spectrum. In a world of finite spectrum resources, CDMA enables many more people to share the airwaves at the same time than do alternative technologies.<br />
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CDMA has greater voice quality and call clarity than other technologies because it filters out background noise, cross-talk and interference. CDMA has fewer dropped calls because it increases voice and date transmission reliability. CDMA has greater spectral efficiency because it packs more transmissions into the same space, resulting in fewer cell sites, which lowers operators' costs. Add to this increased capacity, enhanced privacy, and improved coverage… why would you use any other wireless technology?<br />
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The CDMA air interface is used in both 2G and 3G networks. 2G CDMA standards are branded cdmaOne and include IS-95A and IS-95B. CDMA is the foundation for 3G services: the two dominant IMT-2000 standards, CDMA2000 and WCDMA, are based on CDMA.<br />
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CDMA(Code Division Multiple Access)

The world is demanding more from wireless communication technologies than ever before. More people around the world are subscribing to wire...

1:23 AM

What is Bluetooth?

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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">Bluetooth wireless
technology is a de facto standard, as well as a specification for small form
factor, low-cost, short range radio links between mobile PCs, mobile phones and
other portable devices. The Bluetooth Special Interest Group is an industry group
consisting of leaders in the telecommunications, computing, and networking
industries that are driving development of the technology and bringing it to
market.<o:p></o:p></span></div>
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<b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">How did the need arise?</span></b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;"><o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">In phase with the IT boom, the mobility among people has
constantly grown and wireless technologies for voice and data have evolved
rapidly during the past years. Countless electronic devices for home, personal
and business use have been presented to the market during recent years but no
widespread technology to address the needs of connecting personal devices in
Personal Area Networks (PANs). The demand for a system that could easily
connect devices for transfer of data and voice over short distances without
cables grew stronger.<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">Bluetooth wireless technology fills this important communication
need, with its ability to communicate both voice and data wirelessly, using a
standard low-power, low-cost technology which can be integrated in all devices
to enable total mobility. The price will be low and result in mass production.
The more units around, the more benefits for the customer.<o:p></o:p></span></div>
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<b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">Why Bluetooth ?</span></b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;"><o:p></o:p></span></div>
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<b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">What will Bluetooth
wireless technology deliver to end users?</span></b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;"><o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">It will enable users to connect a wide range of computing and
telecommunications devices easily and simply, without the need to buy, carry,
or connect cables. It delivers opportunities for rapid ad hoc connections, and
the possibility of automatic, unconscious, connections between devices. It will
virtually eliminate the need to purchase additional or proprietary cabling to
connect individual devices. Because Bluetooth wireless technology can be used
for a variety of purposes, it will also potentially replace multiple cable
connections via a single radio link. It creates the possibility of using mobile
data in a different way, for different applications such as "Surfing on
the sofa", "The instant postcard", "Three in one
phone" and many others. It will allow them to think about what they are
working on, rather than how to make their technology work. The solution
eliminates the annoying cable and its limitations regarding flexibility (often
specific for a brand or pair of devices) and range. But, Bluetooth implies more
than that. The technique provides the means for connecting several units to
each other such as setting up small radio LANs between any types of Bluetooth
devices. A number of user scenarios are described. They highlight more
possibilities that reach far beyond just an elimination of the point-to-point
cable.<o:p></o:p></span></div>
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<b><span style="font-family: "Times New Roman","serif"; font-size: 14.0pt; mso-fareast-font-family: "Times New Roman";">History<o:p></o:p></span></b></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">         <o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">By the way if, you're wondering where the Bluetooth name
originally came from , it is named after a Danish Viking and King <b>of
Denmark between 940 and 981 AD</b>, Harald Blåtand (Bluetooth in English), who
lived in the latter part of the 10<sup>TH</sup>  century. Harald
Blåtand united and controlled Denmark and Norway (hence the inspiration on the
name : uniting devices through Bluetooth<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">          The
idea that resulted in the Bluetooth wireless technology was born in 1994 when Ericsson
Mobile Communications decided to investigate the feasibility of a low-power,
low-cost radio interface between mobile phones and their accessories. The idea
was that a small radio built into both the cellular telephone and the laptop
would replace the cumbersome cable used today to connect the two devices.<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">A year later the engineering work began and the true potential of
the technology began to crystallize. But beyond unleashing devices by replacing
cables, the radio technology showed possibilities to become a universal bridge
to existing data networks, a peripheral interface, and a mechanism to form
small private ad hoc groupings of connected devices away from fixed network
infrastructures.<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">The requirements regarding price, capacity and size were set so
that the new technique would have the potential to outdo all cable solutions
between mobile devices. Initially a suitable radio interface with a
corresponding frequency range had to be specified. A number of criteria for the
concept were defined regarding size, capacity and global uniformity. The radio
unit should be so small and consume such low power that it could be fitted into
portable devices with their limitations. The concept had to handle both speech
and data and finally the technique had to work all around the world. The study
soon showed that a short-range radio link solution was feasible.<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">When designers at Ericsson had started to work on a transceiver
chip, Ericsson soon realized that they needed companions to develop the
technique. The associates strove not only to improve the technical solutions
but also to get a solid and broad market support in the business areas of PC
hardware, portable computers and mobile phones. Fear for a market situation
with a multitude of non-standard cable solutions, where one cable is designed
specifically for one pair of devices, was one of the motives that made
competing companies join the project. Ericsson Mobile Communications, Intel,
IBM, Toshiba and Nokia Mobile Phones formed a Special Interest Group (SIG) in
1998.<o:p></o:p></span></div>
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<b>What is  SIG?</b><o:p></o:p></span></div>
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<b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">          </span></b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">In February 1998 the Special Interest Group
(SIG) was formed. Today the Bluetooth SIG includes promoter companies 3Com,
Ericsson, IBM, Intel, Lucent, Microsoft, Motorola, Nokia and Toshiba, and
thousands of Adopter/Associate member companies. By signing a zero cost
agreement, companies can join the SIG and qualify for a royalty-free license to
build products based on the Bluetooth technology.<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">This group represented the diverse market support that was needed
to generate good support for the new Bluetooth<i> </i>technology. In May
of the same year, the Bluetooth consortium announced itself globally. The
assignment of the SIG originally was to monitor the technical development of
short-range radio and to create an open global standard, thus preventing the
technology from becoming the property of a single company. This work resulted
in the release of the first Bluetooth Specification in July 1999.<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">The intention of the Bluetooth SIG is to form a de facto standard
for the air interface and the software that controls it.  The further
development of the Specification still is one of the main tasks for the SIG,
other important ones being interoperability requirements, frequency band
harmonization and promotion of the technology. The Bluetooth wireless
technology was developed by the Bluetooth Special Interest Group, to define an
industry-wide specification for connecting personal and business mobile
devices. More than 1,4000 companies are now members of the Special Interest
Group, signifying the industry’s unprecedented acceptance of the Bluetooth
wireless technology.<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">To avoid different interpretations of the Bluetooth standard
regarding how a specific type of application should be mapped to Bluetooth, the
SIG has defined<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">number of user models
and protocol profiles. These are described in more detail in the section
entitled Bluetooth Usage Models and Profiles.The SIG also works with a
Qualification Process. This process defines criteria for bluetooth product
qualification that ensures that products that pass this process meet the
Bluetooth specification<o:p></o:p></span></div>
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<b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">TECHNOLOGY OVERVIEW:</span></b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;"><o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">The technology is an open specification  for wireless
communication of data and voice. It is low cost short range radio link, built
into a 9X9 mm microchip, facilitating protected ad hoc connections for
stationary and mobile communication environment. Bluetooth technology allows
for the replacement of the many proprietary cables that connect one device to
another device with one universal short range radio link. For instance
Bluetooth radio technology built in both the cellular telephone and the laptop
would replace the cumbersome cables used today to connect the laptop to a
cellular telephone.<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">Printers, PDA’S, desktops, fax machines, keyboard, joysticks and
virtually any other device can be part of the Bluetooth system. But beyond
untethering devices by replacing the cables, Bluetooth radio technology
provides a universal bridge to existing data networks, a peripheral interface,
and a mechanism to form small private ad hoc grouping of connected devices away
from fixed network infrastructures. Designed to operate in noisy radio
frequency environment, the Bluetooth radio uses a fast acknowledgement and
frequency hopping scheme to make the link robust. The Bluetooth radio modules
avoid interference from other signals by hopping to a new frequency after
transmitting or receiving a packet. Compared with other systems operating in
the same frequency band, the Bluetooth radio typically hops faster and uses
shorter packets. This makes the Bluetooth radio robust than the other system.
Short packages and fast hopping also limit the impact of random noise and long
distance links. The encoding is optimized for uncoordinated environment.
Bluetooth radios operate in the unlicensed ISM band at 2.4GHz. a frequency hop
transceiver is applied to combat interference and fading. A shaped binary FM
modulation is applied to minimize transceiver complexity. The gross data rate
is 1mbps. A Time Division Duplex scheme is used for full duplex transmission.
The Bluetooth base band protocol is a combination of circuit and packet
switching. Slots can be reserved for synchronous packet. Each packet is
transmitted in a different hop frequency. A packet nominally covers a single
slot, but can be extended to cover up to 5 slots. Bluetooth can support an
asynchronous data channel, up to 3 simultaneous synchronous voice channels, or
a channel that simultaneously supports asynchronous data synchronous voice.
Each voice  channel supports 64 kbps synchronous (voice) link.<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">The asynchronous channel can support an asymmetric link of
maximally 721 kbps in either direction  while permitting 57.6 kbps in
the return direction, or a 432.6 kbps symmetric link.<o:p></o:p></span></div>
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<b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">INTRODUCTION :</span></b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;"><o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">The Bluetooth technology answers the need for short range wireless
connectivity within three areas :<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">·     Data and voice
access points .<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">·        Cable
replacement<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">·        Ad
hoc networking<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">The Bluetooth technology specification specifies a system solution
comprising hardware, software and interoperability requirements. The Bluetooth
radio operates in a globally available 2.4GHz  ISM  band,
ensuring communication compatibility worldwide.       <o:p></o:p></span></div>
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<b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">Data and voice access
point :</span></b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;"><o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">The Bluetooth technology facilitates real time voice and data
transmission. The technology makes it possible to connect any portable and
stationary communication device as easily as switching on the light. You can,
for instance, surf the Internet & send e-mail on your potable PC or
notebook regardless of whether you are wirelessly connected through a mobile
phone or through a wire bound connection (PSTN, ISDN,LSN,XDLS).<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">          Voice
channel use the <i>Continuous Variable Slope Delta Modulation (CVSD</i>)
coding scheme, and never retransmit voice packets. The CVSD was chosen for its
robustness in handling dropped and damaged samples. Rising interference levels
are experienced as increased background noise; even at bit error rate up to 4%
the CVSD coded voice is quite audible.<o:p></o:p></span></div>
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<b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">CABLE REPLACEMENT:</span></b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;"><o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">The Bluetooth technology
eliminates the use for numerous often proprietary cable attachments for
connection of practically any kind of device. Connections are instant and they
are maintained even when devices are not within line of sight. The range of
each radio is approximately 10 meters but it can be extended around 100 meters
with an optional amplifier.<o:p></o:p></span></div>
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<b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">AD-HOC NETWORKING</span></b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">:<o:p></o:p></span></div>
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<span style="font-family: 'Times New Roman', serif; font-size: 14pt;">A device equipped with Bluetooth radio establishes instant
connection to another Bluetooth radio as soon as it comes into range. Since
Bluetooth technology supports both point to point and point to multi point
connection, several piconets can be established and linked together ad hoc. The
Bluetooth technology is best described as multiple piconet structure.<o:p></o:p></span></div>
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<b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;">Piconet</span></b><span style="font-family: 'Times New Roman', serif; font-size: 14pt;"> is a connection of
devices connected via Bluetooth technology in an ad hoc fashion . A piconet
starts with two connected devices ,such as portable PC and cellular phone and
may grow into eight connected devices. All Bluetooth  devices are
peer units and have identical  implementation. However, when
establishing a piconet, one unit will act as a master and the other as a slave
for the duration of piconet connection.<o:p></o:p></span></div>
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What is Bluetooth?

Bluetooth wireless technology is a de facto standard, as well as a specification for small form factor, low-cost, short range radio links ...

1:56 AM

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Clock less Chips

CDMA(Code Division Multiple Access)

What is Bluetooth?

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