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19th October 2004

Single-chip Bluetooth cordless telephony access point design features a sub-$15 bill of materials

• expert Bluetooth design services allow single-chip solutions for emerging product markets

At WiCon Americas, Cambridge Consultants is unveiling an off-the-shelf reference design for a Bluetooth cordless telephony access point featuring a very low bill of materials of under $15. The cost breakthrough stems from an implementation that uses only the processor integrated on a single-chip Bluetooth device from the market-leading BlueCore family, and is achieved by means of novel application software that runs natively - a technique made possible by Cambridge Consultants' design partnership with the chip maker CSR.

The new design is targeted at an exciting emerging market being pioneered by BT in Europe with its 'Bluephone' initiative, and attracting the attention of many other telcos and virtual network operators around the world. It supports the concept of mobile handsets with Bluetooth being used as more versatile 'three-way' devices: making calls on the cellular network when roaming, but when at home or in range of an access point, using Bluetooth for a cordless connection to the fixed network, or as an intercom to other devices. Although this concept has been discussed before with wireless standards like DECT, the runaway success of Bluetooth in the mobile phone arena is now making it an interesting proposition for the telecommunications industry. Variants of the access point design also support the powerful data communications capabilities of Bluetooth.

Cambridge Consultants is demonstrating a circuit design for a single-line telephony access point suitable for residential applications, but has similar circuits available for related multi-line office and public applications. The design is offered as a reference design ready for manufacture or adaptation - complete with schematics, PCB files, and software - for a one-off license fee or per-unit royalties.

"Our extensive experience in the Bluetooth sector, and design agreement with CSR, allows us to help OEMs enter emerging product markets more quickly, and thereby create leaner and more finely-tuned designs", says Tim Whittaker of Cambridge Consultants. "With this design we have stripped a very significant amount of cost from the usual bill of materials, as well as reducing PCB size and power consumption".

The Bluetooth telephony access point is built around a single-chip BlueCore2 device and its on-chip XAP microcontroller, with a power amplifier to achieve Class 1 performance and support a range of 100 meters (108 yards). Its small bill of materials costs under $15 in OEM volumes. The design uses external Flash memory for the application program, and a low-cost external codec for the Bluetooth-to-PSTN interface. The bill of materials can be reduced even further by migrating the design to a BlueCore device with integral ROM and codec, once a product concept is proven. The design is implemented on a PCB measuring 40x58mm (~1.6x2.3inches).

The application software in the demonstrator implements three Bluetooth Profiles: cordless telephony, hands-free, and headset. A dialler application running on a PDA or phone platform can also be added, for use with a headset. Other Profiles may be added easily, depending on an OEM's product requirements.

In addition to a design partnership with CSR for application-specific single-chip Bluetooth designs, Cambridge Consultants has extensive experience in the 802.15.4/ZigBee market, and a similar software design partnership with the leading vendor in this field, Ember Corporation.

BlueCore is a trademark of CSR, and Bluetooth is a trademark of the Bluetooth SIG.

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