The Bluetooth headset market has experienced impressive growth in the past 5 years with total shipments rising from 7 million units in 2003 to over 60 million headsets produced in 2005. This is set to continue to increase in 2006 and beyond. This, together with the massive adoption in mobile handsets, is turning Bluetooth technology into a globally accepted means of communication. Advances in Bluetooth technology, performance, battery consumption, near field communications, and changes in driving legislation have all contributed to the phenomenal success that the market has enjoyed. However, headset designers are now faced with a number of challenges in order to succeed.

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Tkool Electronics

The Bluetooth headset market has experienced impressive growth in the past 5 years with total shipments rising from 7 million units in 2003 to over 60 million headsets produced in 2005. This is set to continue to increase in 2006 and beyond. This, together with the massive adoption in mobile handsets, is turning Bluetooth technology into a globally accepted means of communication. Advances in Bluetooth technology, performance, battery consumption, near field communications, and changes in driving legislation have all contributed to the phenomenal success that the market has enjoyed. However, headset designers are now faced with a number of challenges in order to succeed.

YACT24MD97HA000000_Datasheet PDF

The Bluetooth headset market has experienced impressive growth in the past 5 years with total shipments rising from 7 million units in 2003 to over 60 million headsets produced in 2005. This is set to continue to increase in 2006 and beyond. This, together with the massive adoption in mobile handsets, is turning Bluetooth technology into a globally accepted means of communication. Advances in Bluetooth technology, performance, battery consumption, near field communications, and changes in driving legislation have all contributed to the phenomenal success that the market has enjoyed. However, headset designers are now faced with a number of challenges in order to succeed.

While it may seem contradictory to ZigBee’s spirit of openness, some OEMs may develop products that do not provide open interoperability at the application layer. Engineers may choose to design private application profiles in order to create a closed ecosystem” of single vendor devices, or select third-party devices.

ZigBee defines an abstract interface while platform vendors provide application programming interfaces (API) that defines rules for how applications integrate into the ZigBee stack. For instance, vendors of commercial HVAC systems, who must make significant investments in the installation of their customers’ HVAC infrastructure, may want to protect that investment from erosion to third-party thermostats and other environmental controls. An engineer should look into the functionality of the platform vendors APIs before choosing their solutions.

YACT24MD97HA000000_Datasheet PDF

Yet, the closed” HVAC system would still benefit third-party product manufacturers at the network level. Required interoperability at ZigBee’s lower stack provides data routing as well as medium access control, network formation and maintenance, and device and service discovery.

So a company installing new ZigBee wireless light switches in the building, for example, would be able to take advantage of the existing transport network provided by the HVAC controllers to help carry traffic.

How that data is transported is another key consideration for developers because ZigBee does not define a transport layer. Design Engineers must decide whether to build the transport mechanism themselves, or they can simply decide to build their application using a ZigBee chip with a built-in transport layer.

YACT24MD97HA000000_Datasheet PDF

For example, Ember provides a transport layer with their ZigBee stack as a way to simplify application development as well as ensure reliable end-to-end messaging. The built-in transport layer provides the framework on which developers can define private ZigBee profiles.

Platform considerations ZigBee provides a standardized network and application framework upon which developers can build applications without having to worry about the intricacies of networking and RF issues.

YACT24MD97HA000000_Datasheet PDF

Yet ZigBee’s standardized framework does not by itself ensure easy product development. The market is flush with a diverse vendor mix of components needed to build ZigBee-compatible applications, including RF transceivers, microcontrollers, flash ROM, vendor-specific protocol stacks and application development tools.

Consequently, design engineers need to choose between rolling their own” ZigBee solution from multi-vendor components or building their applications upon an integrated hardware/software platform. Lacking both the expertise and inclination to tackle the tough integration effort, most developers will probably opt for the latter approach.

At the heart of the Impulse C programming model are processes and streams (Fig 2 ). Processes are independently synchronized, concurrently operating portions of an application that are written in a standard language (in this case C language). Processes perform the work of the application by accepting data, performing computations, and generating relevant outputs.

Unlike traditional C subroutines, Impulse C processes are considered persistent; they are normally invoked once (whether in hardware or software) and continue as long as there is data available to be processed. The data processed by such an application flows from process to process by means of streams, or in some cases by means of messages or shared memories, which are also supported in the programming model.

In Impulse C, streams represent unidirectional communication channels that are used to connect multiple parallel processes, whether hardware or software. Each stream is defined by a data width (in bits, usually ranging from 8 to 128, depending on the application and the target platform), and a buffer depth, which is usually 1 or some other small number reflecting the depth of the generated stream buffers.

These streams are read and written using the Impulse C functions co_stream_read and co_stream_write , which read and write packets of data from the stream in a synchronized way. If there is no data on an input stream, the co_stream_read function will block until data is available; if an output stream is already full, the co_stream_write function will block until a receiving processes reads a packet of data, making space in the stream for additional data to be written.

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