Developed two decades ago by Ericsson, Bluetooth is one of the most common wireless communication technologies seen in consumer electronics. Unlike Wi-Fi (IEEE 802.11 standards), it usually serves a category of applications known as wireless personal-area network (WPAN). The low energy profil of Bluetooth has made it popular in consumer electronics arena, while Wi-Fi is seen in more institutional setups.
Bluetooth Smart, aka Bluetooth Low Energy
The most important feature of Bluetooth Smart is its extremely low power requirement. Along with its reduced size and very low cost, this allows it to be used on sensors as miniature data loggers. Furthermore, as Bluetooth Smart uses the same frequency band as classic Bluetooth, it is compatible with almost every Bluetooth-enabled mobile device.
There are a wide variety of chips available to get you started on integrating Bluetooth Smart technology into your device.
Navaneethan Sundaramoorthy, an independent technology, innovation and education consultant, explains, “There are three broad approaches for integrating Bluetooth into your embedded system design, which vary based on the cost, level of integration and development effort. One option would be to use individual components like an antenna, microcontroller and power supplies directly on your board. The second option is use of pre-integrated Bluetooth PCB modules that can be soldered on your board. Alternatively, you can use off-the-shelf USB (or SDIO) Bluetooth dongles connected to your board.”
“Of these three approaches, use of Bluetooth modules is the most popular approach for embedded systems. These modules have the complete Bluetooth software stack burnt into the microcontroller’s Flash memory, and are 100 per cent factory tested and even certifiedfor various wireless standards,” he adds.
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Bluetooth Smart finds applications in many consumer electronics, automotive, and industrial, segments such as smartphones and tablets, keyboards and mice, TV remote controls, sports and fitness, toys, gaming, automotive infotainment, etc.
Products which previously used on other proprietary wireless (ISM band) and infra-red (e.g., IrDA) connectivity technologies are migrating to Bluetooth Smart connectivity to benefit from lower power/voltage operation, much longer battery life (years not months), non line-of-sight and two-way operation, etc. The major OS providers have announced the integration of a native Bluetooth Smart stack into their updates and upgrades so that cool “Appcessories” (e.g., a smartphone app for a Bluetooth connected accessory) can be developed. There’s an exciting range of upcoming consumer electronics products that are ready for Bluetooth Smart, such as smart watches, door-key fobs, camera accessories, health and fitness monitors, proximity alarms, keyboards, mice, gesture-based remote-controls, tablets and laptops, to name a few.
—Nitin Gupta, Lead Engineer, µEnergy Applications Group, CSR
Single-chip processor. Single-chip processor is the firt choice when a designer is looking for the smallest possible footprint along with minimal power consumption, while keeping performance on par with standards. It is also selected when the developer wants to keep the costs as low as possible while implementing his Bluetooth system—for example, when creating Bluetooth client devices.
CSR has a single-chip radio with an integrated 16-bit microprocessor and 64 kB each of RAM and ROM. Named CSR1011, it comes with I2C peripheral and SPI debug interfaces, as well as a development kit and SDK that can be accessed at the CSR website.
Broadcom’s BCM20702 is another single-chip Bluetooth processor, but built on the 65nm LP CMOS technology. It has a built-in amplifier to support Class 1 transmit power. This chip features a packet loss concealment technology that reduces packet loss and bit error rates. This makes it a good choice for audio output devices that rely on a Bluetooth link for audio streaming.
One of the lowest-voltage Bluetooth Smart controllers currently available is the EM9301 by EM Microelectronic. This controller operates at 0.8 V, which makes it a good choice for cases where power might be a very precious resource—such as in solar cells, piezo-electric and other energy harvesters.
Multifunction processors. Unlike single-chip processors, these RF silicon chips come with a variety of communication technologies apart from Bluetooth. The chips are targeted at applications where a variety of wireless technologies would be used simultaneously. As such, they come with technology that works to mitigate potential interference between the various wireless technologies (explained later).
Broadcom’s BCM2076 is one such combo chip that features Bluetooth Smart and FM, and also supports both the GPS constellation as well as the GLONASS constellation. There is also an integrated technology in the chip, called InConcert, that allows Bluetooth and Wi-Fi signals to coexist without interfering.
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There are many chipset and module makers, viz, Broadcom, ConnectBlue, Panasonic, Bluegiga, InsightSiP and Blue Radio. All of their modules are based on common TI CC2540/41 chipset stacks. Only InsightsiP’s product is built with Nordic nRF8001 chipset.
External host interface. In Blue Radio module, the built-in API for external host uses AT commands, which are extremely easy to integrate with existing libraries. Bluegiga has a binary API dependant on ANSI C library.
Application hosting. In case of BLE, to save on power, cost and complexity, applications are typically hosted on the modules themselves. Application hosting on Bluegiga module is free, while it costs almost 60 per cent less on Blue Radio compared to other modules.
Pricing. Blue Radio module is costlier, while Bluegiga module is the cheapest and the rest of them are averagely priced.
Certifications. Modules based on a technology like Bluetooth must be certified for CE and FCC standards. Other certifications are not mandatory but desirable. Bluegiga modules carry five certifications compared to basic certifications carried by other modules. Having certifications already in place certainly reduces cost and speeds up the development.
All in all, it seems that Blue Radio and Bluegiga modules should be preferred in designs followed by Panasonic and ConnectBlue modules.
T. Anand, MD, Knewron
BLE system-on-chips. Since the proliferation of the Internet of Things, or the Electronics of Things as we may like to call it, there has been a surge in the demand to create wireless personal area networks for each tech-savvy person (including me). We have most of our personal belongings tagged with a Bluetooth ‘sticker,’ which gives these objects a virtual representation of themselves. The benefit is to track and easil locate every piece of accessory that I carry about with me. While single-chip Bluetooth radios are good, cases like these demand a dedicated system-on-chip (SoC) that can handle all the functions on one very small chip.