`
`Henrik Arfwedson and Rob Sneddon
`
`In just over a year, more than 1,600 companies have adopted Bluetooth,
`making it one of the fastest growing technologies ever. By 2002, it is esti-
`mated that more than 100 million mobile phones, computers and other
`types of electronic equipment will incorporate this technology. Bluetooth,
`which is a short-range radio communication link developed and intro-
`duced by Ericsson, is currently in the process of becoming an accepted
`world standard.
`The authors describe various technical constraints and considerations
`associated with the development of Ericsson’s Bluetooth modules. When
`these modules are used together with the accompanying OS-independent
`software stack, customers can focus their R&D resources on developing
`specific hardware and software for their Bluetooth applications. The
`authors also discuss the main issues that developers need to consider
`when designing Bluetooth-enabled equipment.
`
`TRADEMARKS
`
`trademark owned by
`is a
`Bluetooth™
`Telefonaktiebolaget LM Ericsson, Sweden.
`
`Background
`In 1994, Ericsson Mobile Communications
`launched an initiative to study low-power,
`low-cost radio interfaces between mobile
`phones and their accessories. A radio-access
`solution was sought because it would elim-
`inate the need for cables and overcome line-
`of-sight restrictions. It was also recognized
`that a low-cost solution would usher in wire-
`less connectivity for a multitude of new ap-
`
`Figure 1
`User model with local wireless connectivity. Applications envisioned for the near future.
`
`LAN
`
`Access point
`
`Headset
`
`Mobile phone
`
`Cellular network
`
`Laptop
`
`Printer
`
`Piconet
`
`Mouse
`
`Laptop
`
`198
`
`plications and give rise to a host of associat-
`ed components and devices.
`For more than ten years, Ericsson Micro-
`electronic has been involved in the research
`and development of semiconductor and
`packaging technologies for wireless appli-
`cations. Capitalizing on this experience,
`Ericsson’s engineers have realized a truly
`low-cost, high-density
`solution—Blue-
`tooth.
`
`Industry-wide commitment
`Bluetooth was envisioned to be an open,
`global standard. To achieve a critical mass
`and to promote a joint worldwide standard,
`Ericsson approached IBM, Intel, Nokia and
`Toshiba with its concept. In May 1998, the
`Bluetooth Special Interest Group (SIG) was
`announced, and within 18 months more
`than 1,600 companies had signed the Blue-
`tooth Adopters Agreement. Today, based on
`massive global interest and support for the
`technology, analysts are predicting that by
`2002 over 100 million mobile phones, com-
`puters and other electronic devices will in-
`corporate Bluetooth technology. Bluetooth
`specifications are issued under the authori-
`ty of the Bluetooth SIG.
`
`Universally recognized technology
`Each Bluetooth unit has a unique identity.
`Equipment enabled with Bluetooth tech-
`nology automatically searches the vicinity
`for other Bluetooth-compliant equipment.
`On contact, information is exchanged al-
`lowing the systems to determine whether or
`not to establish a connection. At this first
`encounter, the Bluetooth devices transmit a
`personal identification number (PIN). After
`that, no further identification process is nec-
`essary. Up to eight devices can operate at the
`same time in a Bluetooth cell. Moreover,
`each Bluetooth device can be active in sev-
`eral cells at the same time.
`
`Basic operation
`To minimize the risk of disturbance from
`other radio devices, such as microwave
`ovens, garage door openers, and so on, a
`frequency-hop scheme causes the system to
`switch 1,600 times per second through 80
`channels. This means that if one frequency
`channel is blocked, the disturbance to Blue-
`tooth communications will be limited. It
`also means that several Bluetooth networks
`can run concurrently without disturbing
`one another. First-generation Bluetooth-
`enabled equipment can exchange informa-
`tion at a rate of 1 Mbit/s at a range of up to
`
`Ericsson Review No. 4, 1999
`Zepp Labs, Inc.
`ZEPP 1033
`Page 1
`
`
`
`BOX A, ABBREVIATIONS
`
`ANSI
`
`API
`ASIC
`
`BGA
`CMOS
`
`EMC
`ETSI
`
`FCC
`
`HCI
`IC
`lrDA
`
`American National Standards Insti-
`tute
`Application program interface
`Application specific integrated cir-
`cuit
`Ball grid array
`Complementary metal-oxide semi-
`conductor
`Electromagnetic compatibility
`European Telecommunications
`Standards Institute
`Federal Communications Commis-
`sion
`Host Controller Interface
`Integrated circuit
`Infrared Data Association
`
`tooth plug on the Ericsson phone. To an-
`swer or initiate a call (using a voice-
`recognition-capable phone, such as the T28,
`T28 World or R320), the user presses a key
`on the headset. Because the Bluetooth radio
`link covers distances of up to 10 meters, the
`phone can be left in the user’s briefcase, a
`coat pocket, or even in another room.
`Weighing a mere 20 grams, the Bluetooth
`Headset sits comfortably on either ear.
`
`10 meters. Also, because Bluetooth operates
`in the global industrial-scientific-medical
`(ISM) band at frequencies between 2.4 and
`2.5 GHz, it has the potential to become a
`universally recognized standard.1
`
`Market confidence
`Having convinced both the telecommuni-
`cations industry and the wider electronics
`industry of the viability of the Bluetooth
`concept, it has been recognized that prod-
`ucts based on Bluetooth technology must be
`developed, demonstrated and delivered
`quickly in order to maintain the interest and
`confidence of these market sectors.
`The first goal—to produce actual product
`demonstrators—has already been achieved.
`Through enormous efforts of many diverse
`groups of design and development engi-
`neers, Ericsson has been first to successfully
`demonstrate Bluetooth compliance in real
`telecommunication products at recent trade
`shows. With market confidence in the tech-
`nology established, efforts are now being fo-
`cused on Bluetooth products and product
`support for the two major markets—that
`is, for
`• applications within telecommunications;
`and
`• applications within PCs and other elec-
`tronic equipment.
`
`Bluetooth-enabled products from
`Ericsson
`Within Ericsson, more than twenty separate
`projects for “Bluetooth-enabled” products
`are currently under way. These projects,
`which cover a wide spectrum of applications,
`are being coordinated through the Ericsson
`Bluetooth technology council—to ensure
`that common Bluetooth features and key
`support activities are properly controlled,
`and that effective use of resources is main-
`tained. Within these Ericsson products, the
`Bluetooth function can be integrated into
`the application to achieve maximum system
`optimization.
`At Mobile Focus and COMDEX/Fall’99,
`in Las Vegas, USA, Ericsson unveiled the
`Bluetooth Headset, a practical headset that
`connects to a mobile phone by a radio link
`instead of a cable. This is the first hands-free
`accessory to incorporate Bluetooth technol-
`ogy. The Bluetooth Headset will be avail-
`able on the market in mid-2000.
`The Bluetooth Headset is a lightweight,
`wireless mobile phone headset with a built-
`in Bluetooth radio chip that functions as a
`connector between the headset and a Blue-
`
`Ericsson Review No. 4, 1999
`
`Low-temperature, co-fired, ceramic
`LTCC
`Operating system
`OS
`Pulse code modulation
`PCM
`Personal identification number
`PIN
`Public switched telephone network
`PSTN
`Radio frequency
`RF
`RFCOMM Serial Port Emulation based on ETSI
`TS07.10
`Receiver
`Service discovery protocol
`Special interest group
`Transmitter
`Universal asynchronous receiver
`and transmitter
`Universal serial bus
`Voltage-controlled oscillator
`
`RX
`SDP
`SIG
`TX
`UART
`
`USB
`VCO
`
`Figure 2
`Ericsson’s Bluetooth Headset is the first
`hands-free accessory to incorporate Blue-
`tooth technology.
`
`199
`Zepp Labs, Inc.
`ZEPP 1033
`Page 2
`
`
`
`Volume
`Part price
`Profit
`
`Figure 3
`A typical product cycle.
`
`Time
`
`Bluetooth products and
`product support for
`developers
`
`As already stated, in order for Bluetooth to
`become accepted, many telecommunica-
`tions, PC, and other electronic system de-
`velopers must adopt the technology within
`their products. In terms of Bluetooth inte-
`gration, these developers range from the
`very sophisticated to the complete novice.
`Accordingly, Ericsson has developed a
`multi-track strategy that addresses the
`needs of diverse customers. Ericsson offers a
`Bluetooth Starter Kit and a complete Blue-
`tooth Developer Kit for Bluetooth evalua-
`tion. Finally, to support the software stack,
`Ericsson has partnered with Symbionics.
`
`Bluetooth partitioning
`The simplest solution for most developers is
`to buy a complete Bluetooth module from
`Ericsson. The module includes radio fre-
`quency (RF) and baseband circuits, FLASH
`memory, and the associated software stack.
`However, if developers want to integrate the
`Bluetooth baseband (EBC) themselves, they
`need only buy a Bluetooth RF module,
`which is designed to be compliant to the
`Bluetooth RF interface specification. Before
`undertaking their own integration, devel-
`opers should carefully consider time to mar-
`ket, product cycles, and profitability.
`
`Microelectronics for Bluetooth
`The Bluetooth module development
`roadmap is closely associated with the ASIC
`development roadmap. On first-generation
`Bluetooth modules, the RF ASIC has been
`designed on biCMOS technology; the base-
`band ASIC has been designed on comple-
`mentary metal-oxide
`semiconductor
`
`Figure 4
`Typical time scale for developing a family
`of ASIC chipsets from scratch. The first-
`generation end product takes approxi-
`mately two years to develop. Each subse-
`quent generation takes about one year to
`develop.
`
`Baseband ASIC
`
`RF ASIC
`
`System demonstrator
`
`Second-generation
`chipset
`
`Third-generation
`single chip
`
`0
`
`1
`
`2
`
`3
`
`4
`
`Years
`
`200
`
`(CMOS) technology. The general trend fol-
`lowed by ASIC silicon technologies is to-
`ward processes with smaller geometries and
`lower supply voltages. Apart from reducing
`cost per function, this approach also permits
`greater levels of integration. However, al-
`though many future-generation products
`will benefit from the implementation of
`single-chip modules, there will continue to
`be applications in which the optimum level
`of integration employs a two-chip solution.
`
`Optimum levels of ASIC and module
`integration
`Several factors that could influence decisions
`concerning the optimum level of integra-
`tion are:
`• circuit compatibility—digital and RF
`circuits do not mix well;
`• functional
`stability—future products
`may require baseband ASIC migration to
`accommodate additional functionality or
`to take advantage of a less expensive
`process while the RF interface remains
`stable; and
`• cost—depending on the choice of tech-
`nology, a multi-chip solution might cost
`less than a single-chip solution.
`
`Product cycle and profitability
`Sales volumes grow for a short period after
`a new product has been introduced. This in-
`troductory period is followed by a long pe-
`riod during which sales volumes remain sta-
`ble. Finally, sales volumes decline as market
`demand decays, or the product is superseded
`or becomes obsolete (Figure 3).
`Initial production volumes do not begin
`to generate profits until development costs
`have been recovered. Once this milestone
`has been passed, profit per unit increases,
`due to improvements in production and
`yield. In time, however, profit per unit de-
`clines, due to price erosion and increased
`competition.
`The key point to be made is that the end
`of the product cycle should be thought of as
`being fixed in time. Consequently, any delay
`in delivering volumes to the market will re-
`sult in loss of profit during the most prof-
`itable phase of the product cycle. Figure 4
`shows typical time scales for the develop-
`ment from scratch of a family of ASIC
`chipsets. The first-generation product takes
`approximately two years to develop. Each
`subsequent generation takes about one year
`to develop. The ASIC development
`cycles are on the critical path for product
`development.
`
`Ericsson Review No. 4, 1999
`Zepp Labs, Inc.
`ZEPP 1033
`Page 3
`
`
`
`First generation
`
`Second generation
`
`Third generation
`
`biCMOS
`0.5 μm
`
`CMOS
`0.25 μm
`
`biCMOS
`0.25 μm
`
`CMOS
`0.25 μm
`
`biCMOS
`0.25 μm
`
`CMOS
`0.15 μm
`
`CMOS
`0.15 μm
`
`CMOS
`0.15 μm
`
`RF
`
`Baseband
`
`Single
`
`ASIC technology and
`chipset roadmaps
`Figure 5 shows the ASIC technology
`roadmap for Bluetooth ASICs. Where RF
`chips are concerned, the commercial avail-
`ability of the manufacturing process deter-
`mines which ASIC technology is used for each
`generation. Because digital CMOS technol-
`ogy is nearly always more advanced, each gen-
`eration of baseband ASICs can generally be
`designed on smaller geometries. However,
`
`for second-generation products, the baseband
`ASIC design remains on the 0.25 microme-
`ter technology node, to accommodate the op-
`tion of merging the baseband ASIC with the
`RF ASIC on a biCMOS single-chip solution.
`All third-generation ASICs are based on 0.15
`micrometer CMOS technology. In this case,
`the main reason to maintain a separate RF
`ASIC is to accommodate developers who only
`require the RF module.
`Figure 6 shows the equivalent chipset
`roadmap. The third-generation ASICs have
`
`Figure 5
`Typical technology roadmap.
`
`First generation
`
`Second generation
`
`Third generation
`
`Figure 6
`Typical chipset roadmap.
`
`Multiple chip
`alternatives
`
`Baseband
`0.25 μm
`
`FLASH
`
`Baseband
`0.25 μm
`
`FLASH
`
`RF module
`RF
`0.5 μm
`
`RF module
`RF
`0.25 μm
`
`FLASH
`
`RF + BB module
`RF+BB
`0.25 μm
`
`Single-chip
`alternatives
`
`Ericsson Review No. 4, 1999
`
`Baseband
`+ ROM
`0.15 μm
`
`RF module
`RF
`0.15 μm
`
`Single-chip
`module
`RF+BB
`0.15 μm
`
`201
`Zepp Labs, Inc.
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`
`
`
`LTCC
`
`Figure 7
`Illustrated profile of the Bluetooth radio
`module from Ericsson Microelectronics
`(height: 1.66 mm; width: 10.2 mm; depth:
`14.0 mm).
`
`BGA solder ball
`
`Discrete
`
`Flip-chip
`
`IC
`
`Mother board
`
`absorbed the external FLASH memory of
`previous generations. This cannot be done
`until the product functionality is known to
`be stable.
`
`Packaging
`Recent developments in flip-chip and mod-
`ule technologies can greatly benefit the con-
`trol and minimization of circuit parasitics,
`reduce overall costs, and introduce less strin-
`gent requirements regarding the placement
`of ASIC bonding pads.
`
`RF module design
`The radio transceiver function consists of an
`RF integrated circuit (IC) and some 50 dis-
`
`crete components that have been integrated
`into a single module (Figures 7 and 8).
`Important factors that affect the selection
`of technology and design are:
`• small dimensions, including a maximum
`height of 1.6 mm;
`• low cost and ability to manufacture large
`volumes; and
`• a reusable module that can be included in
`numerous applications.
`The decision to package the function as a
`single-surface mountable device was made
`very early. The size requirements of the RF
`IC led developers to choose a flip-chip as-
`sembly process. This technology, which has
`been in use for 25 years, is considered the
`
`Figure 8
`Photograph of the Bluetooth radio module.
`
`202
`
`Ericsson Review No. 4, 1999
`Zepp Labs, Inc.
`ZEPP 1033
`Page 5
`
`
`
`ultimate assembly and interconnect solu-
`tion. Until recently, however, it was an ex-
`clusive and costly technology that could be
`handled by only a few companies.
`The small size, and requirements for flip-
`chip compatibility and high-frequency per-
`formance and mechanical properties led de-
`velopers to select low-temperature, co-fired,
`ceramic (LTCC) substrates. This decision
`was based on the availability and maturity
`of the LTCC technology, vendor compati-
`bility, and the promise of denser integration
`in the future.
`The LTCC technique allows engineers to
`integrate microwave structures for the an-
`tenna filter and the receiver (RX) and trans-
`mitter (TX) baluns in the substrate. Laser
`trimming of the critical voltage-controlled
`oscillator (VCO) tank gives high perfor-
`mance. Dense component packing and the
`integration of functions in the substrate re-
`sult in well-balanced utilization of the sub-
`strate’s top and inner layers.
`Simplicity and mainstream technology
`characterize the design. Because the module
`is assembled on one side (single-side assem-
`bly), all components can be soldered in a sin-
`gle operation (reflow soldering). The ground
`plane in the substrate and ball grid array
`(BGA) balls in the periphery of the substrate
`form electrical shielding.
`
`The Bluetooth module
`Ericsson has developed a short-range Blue-
`tooth module that consists of three major
`functional parts mounted on a printed cir-
`cuit board. These are a baseband con-
`troller, FLASH memory and the RF mod-
`ule. The Bluetooth module, which com-
`plies with universal serial bus (USB) and
`universal asynchronous receiver/transmit-
`ter (UART) or pulse code modulation
`(PCM) interfaces, supports voice and data
`transmission. Suggested application areas
`that can be addressed by this module in-
`clude:
`• portable computers;
`• handheld devices;
`• cameras;
`• mobile phone accessories;
`• computer peripherals; and
`• interfaces to the fixed-line access network.
`Designing a Bluetooth-
`enabled product
`Three important areas need to be considered
`before designing a complete Bluetooth-
`enabled product:
`
`Ericsson Review No. 4, 1999
`
`RFCOMM
`
`SDP
`
`L2CAP
`
`HCI driver
`
`PCM
`
`UART or USB
`
`Audio
`
`HCI
`
`Link manager
`
`Baseband
`
`Radio
`
`• Bluetooth hardware, firmware and soft-
`ware;
`• antenna design and production; and
`• application-specific software program-
`ming.
`Note: in the context below, we assume that
`Ericsson’s Bluetooth module
`(or an
`RF module-plus-discrete solution) and
`the operating system-independent (OS-
`independent)
`stack have been used
`(Figure 9).
`
`The application
`Many major applications have already been
`identified for Bluetooth, most of which
`presently communicate and transfer data via
`cable or Infrared Data Association (IRDA)
`connections (or in some instances via flop-
`py disks). However, Bluetooth has the po-
`tential to create completely new areas of ap-
`plications. When deciding how to imple-
`ment an application using Bluetooth tech-
`nology, engineers must first address the
`Bluetooth profile: all Bluetooth devices
`must conform to one or more profiles as stip-
`ulated by the Bluetooth profile specification
`
`Figure 9
`Ericsson’s Bluetooth module and OS-
`independent software stack.
`
`203
`Zepp Labs, Inc.
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`Page 6
`
`
`
`Generic access profile
`
`Service discovery
`application profile
`
`Serial port profile
`
`Dial-up networking
`profile
`
`Fax profile
`
`Headset profile
`
`LAN access profile
`
`Figure 10
`Profiles in Specification 1.0A.
`
`TCS-BIN-based profiles
`
`Cordless phone
`profile
`
`Intercom profile
`
`Generic object exchange profile
`
`File transfer profile
`
`Object push profile
`
`Synchronization
`profile
`
`(Figure 10), which defines mandatory and
`optional messages, procedures, and features.
`Interoperability is the main reason for defin-
`ing different profiles for different usage
`models. New services that do not comply
`with a standard profile can be implement-
`ed, but they must be referred to as non-
`standard Bluetooth profiles.
`
`Mechanics
`The definition or selection of device pack-
`ages should be started as early as possible
`during the product development phase.
`Prime considerations are
`• package materials;
`• parasitic effects; and
`• size.
`Ordinarily, between six and twelve months
`are needed from design to volume produc-
`tion of a new package. Obviously, the me-
`chanics of the product put constraints on the
`choice of components and antenna imple-
`mentation.
`
`Bluetooth components
`The height and size constraints of the ap-
`plication will influence the decision to use
`either a discrete or modular solution when
`implementing the physical hardware with
`Ericsson Bluetooth components, including
`• the Ericsson Bluetooth module; or
`• the Bluetooth RF module, plus baseband,
`
`204
`
`FLASH, and associated components.
`Thanks to Ericsson’s Bluetooth module and
`the OS-independent software stack, most of
`the developer’s work on the software and
`hardware core can be devoted to the appli-
`cation level.
`
`Antennas
`Antenna design is affected by the availabil-
`ity or lack of space (physical volume). De-
`velopers must thus obtain input from the
`antenna designers early on in the project.
`Important parameters are space (volume),
`package shielding of the product, and pro-
`duction tolerances. When designing the
`mechanical structure of the product, devel-
`opers need to have decided whether they will
`use an omnidirectional or a high-gain an-
`tenna—Ericsson can provide information
`and support.
`
`Ericsson Bluetooth development tools
`The development kits provided by Ericsson
`greatly simplify the design of application-
`specific hardware and software. Two sepa-
`rate hardware platforms are available:
`• the Ericsson Bluetooth Developer Kit,
`which contains discrete components and
`provides access to all hardware interfaces.
`This kit could be regarded as the standard
`platform for Bluetooth product develop-
`ment; and
`• the Ericsson Bluetooth Starter Kit, which
`uses the Bluetooth module for imple-
`menting Bluetooth functionality.
`The following application program inter-
`faces (API) will be available in each kit:
`• API on HCI;
`• API on RFCOMM; and
`• API on SDP.
`Most profiles depend on the RFCOMM pro-
`tocol and the application-specific software
`that works on top of RFCOMM.
`
`Ericsson Bluetooth hardware and
`firmware
`Three hardware interfaces are used with the
`Bluetooth module or a discrete equivalent
`solution:
`• UART and PCM voice over the PCM in-
`terface;
`• USB voice over the USB interface; and
`• UART or USB is used for control and data
`transmission.
`A host-controller-interface (HCI) driver for
`the chosen hardware interface is needed to
`drive the Bluetooth module, which pro-
`vides the functionality for receiving HCI
`commands from, and sending HCI events
`
`Ericsson Review No. 4, 1999
`Zepp Labs, Inc.
`ZEPP 1033
`Page 7
`
`
`
`to, the host application; for setting up links;
`and for handling timers. The module also
`handles the actual transmission of data and
`voice traffic. The formats of HCI com-
`mands, events, data packets, and other
`Bluetooth protocols have been formalized
`in Specification of the Bluetooth System vl.OA.
`
`OS-independent software
`High-layer protocols are implemented in
`source code. Ericsson will license the
`portable OS-independent software stack
`(written in ANSI C code) for mass produc-
`tion of devices using Ericsson Bluetooth
`products. Thanks to the OS-independent
`stack, software developers need only work
`with high application-specific
`layers.
`Nonetheless, all implementations of the ap-
`plication software must comply with the
`profile specification: Specification of the Blue-
`tooth System Profiles vl.OA.
`
`Qualification
`
`The Bluetooth SIG has outlined a formal
`qualification program. To pass this pro-
`gram, all products must adhere to the fol-
`lowing Bluetooth-specific criteria (use of
`the Ericsson Bluetooth module will fulfill
`the first two criteria):
`• radio link;
`• protocols (lower layers);
`• profiles; and
`• end-user information.
`The qualification program protects the
`value of the Bluetooth brand by ensuring
`product interoperability and radio link
`quality. Manufacturers whose products pass
`the qualification program may take advan-
`tage of IP licensing and use the Bluetooth
`brand name.
`
`Type approval
`
`Before a product may be introduced into the
`market of any given country, it must be
`“type approved” according to national or re-
`gional regulations. Regulations are grouped
`according to
`• spectrum constraints;
`• radio and telecommunication require-
`ments;
`• electromagnetic compatibility
`and safety;
`• connection to the public-switched tele-
`phone network (PSTN) and encryption; and
`• labeling, test reports and procedures.
`Ericsson’s Bluetooth module will be pre-
`certified according to regulations by the
`Federal Communications Commission
`(FCC) and the European Telecommunica-
`
`(EMC)
`
`Ericsson Review No. 4, 1999
`
`tions Standards Institute (ETSI). Moreover,
`it contains the procedures for putting the
`device into all necessary test modes.
`
`Conclusion
`Bluetooth—which is a wireless technology
`standard introduced by Ericsson, IBM,
`Nokia, Intel and Toshiba in May 1998—
`uses short-range radio signals to connect two
`or more (up to a maximum of eight) devices,
`such as mobile phones, computers, hand-
`held devices, household appliances, auto-
`mobiles, consumer electronics and office
`equipment.
`The Bluetooth module is a standard com-
`ponent from Ericsson Microelectronics
`that can easily be designed into a wide
`range of applications for Bluetooth com-
`munication. Thanks to the advanced flip-
`chip assembly of the integrated circuit, a
`low-temperature, co-fired ceramic sub-
`strate, and ball-grid array assembly to the
`application PBA, the radio module is rel-
`atively small. Ericsson will begin large-
`volume manufacturing of the module dur-
`ing the first quarter of 2000.
`Companies who use Ericsson’s Bluetooth
`module, the OS-independent stack, and
`other components for designing Bluetooth-
`enabled devices can focus their R&D re-
`sources on developing application-specific
`hardware and software.
`In May, 1999, Ericsson launched the
`Ericsson Bluetooth Developer Kit, a “tool-
`box” of equipment that provides developers
`with a flexible environment for designing
`Bluetooth applications in less time and at
`lower cost, and for integrating Bluetooth
`technology into a wide range of electronic
`devices.
`
`REFERENCES
`
`1 Haartsen, J.: Bluetooth—The universal radio
`interface for ad hoc, wireless connectivity.
`Ericsson Review Vol. 75
`(1998): 3,
`pp. 110-117.
`
`205
`Zepp Labs, Inc.
`ZEPP 1033
`Page 8
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