Document 6506351
Transcription
Document 6506351
How to Simplify Effective Bluetooth® Implementations in Smart, Low-Power Applications By Toshiba Electronics Europe Summary Low-Energy (LE) technology in the latest Bluetooth® 4.0 standard is providing an effective platform for a new generation of smart, networked applications. Smart metering, personal wellness and sport monitoring, home automation and other emerging applications can all benefit from Bluetoothʼs ability to exchange or collect information from a variety of sources for control, sensing and measurement purposes. This paper looks at the background to the technology and describes an implementation that simplifies the adoption of Bluetooth in a wide range of embedded applications. Introduction: Building on Bluetooth® Since the Bluetooth standard was first published, Bluetooth Special Interest Group (SIG) members and developer communities have been quietly filling consumersʼ lives with shortrange wirelessly-connectable products such as mobile phones, headsets and PC dongles. According to InStat Research, more than two billion Bluetooth-enabled devices will ship in 2013. As the middle member of a “holy trinity” of industry standards for wireless communication, sitting between ZigBee® low data-rate wireless aimed at applications such as mesh networking and multi-gigabit Wi-Fi™ (IEEE 802.11x) targeting WLAN and Internet connectivity, Bluetooth (which supports data rates up to 2.1Mbit/s) offers advantages such as low design risks for product developers, fast time to market, access to a large pool of developer skills, and certified interoperability scheme with certified compliant devices from other manufacturers. Interoperability enhances the marketability of Bluetooth devices, encourages development of new and innovative products and applications, provides flexibility for end users to mix and match products from various manufacturers, and ultimately serves the Bluetooth SIGʼs vision of enabling seamless ad-hoc connectivity. Bluetooth has become a key factor driving almost universal consumer awareness of and demand for wireless connectivity between personal and mobile devices. If the initial “killer app” was the mobile phone headset, aided by widespread legislation to prevent drivers using handheld mobiles, the subsequent growth of phenomena such as social media, smart metering, personal wellness and sport monitoring, and home automation present a diverse and growing range of further opportunities for Bluetooth as a ubiquitous, low-cost, ad hoc wireless networking technology. The World Moves On These and other emerging applications could benefit from Bluetoothʼs ability to exchange or collect information from a variety of sources for control, sensing and measurement purposes. However, the legacy Bluetooth 2.0 and 3.0 standards are not well suited to ultra low-power applications such as use in tiny sensors that may need to operate from a small power source such as a button cell for periods sometimes as long as several years without requiring replacement of the cell. To encourage selection of Bluetooth as the standard of choice for these applications, the Bluetooth SIG adopted the Bluetooth 4.0 standard in 2010. An important aspect of the latest update is the addition of low-energy technology to the Bluetooth core specification. Bluetooth Low-Energy (LE) enhances scope to take advantage of established Bluetooth performance benefits in low-power battery-operated sensing applications. Bluetooth LE significantly reduces peak, average and idle-mode power consumption, using techniques such as speeding up connection and disconnection processes, thereby enabling a lower total energy budget for the application. Figure 1 compares the time to execute corresponding processes in standard Bluetooth BR/EDR protocols and Bluetooth LE, showing that Bluetooth LE can be more than ten times faster from connection setup to data transfer. Figure 1. Speeding up connection/disconnection processes. Bluetooth LE Applications With this LE technology, the Bluetooth SIG is expecting the first new product introductions to be focused on healthcare and fitness products. This vision encompasses devices such as heart-rate monitors, watches, foot pods, GPS locators and pedometers that will enable sports people to collect more accurate performance data. These, as well as medical devices such as stethoscopes, glucose meters and pulse oximeters, will deliver advantages such as more flexible, un-tethered use. Many will leverage Bluetooth connectivity in devices such as PCs and mobile phones to permit easy wireless syncing, enabling data to be collected, processed, analysed and shared easily and simply. The first Bluetooth 4.0 enabled medical and fitness products reached the store-shelves in 2011. Many other applications are being considered or evaluated, such as a promising Bluetoothbased traffic detection system trial in Houston. Using low-power Bluetooth-enabled sensors positioned at the roadside in busy districts of the city, the pilot scheme tracks anonymous MAC addresses of Bluetooth devices in passing vehicles as they progress through the cityʼs traffic. This enables traffic conditions to be assessed accurately in real time without the huge expense of automatic vehicle recognition technologies, such as visual number plate recognition. Bluetooth LE operation is a key enabler of the system, as it permits small, battery-powered nodes positioned at the roadside to collect the information needed to monitor traffic movements. This saves the expense of providing wired connections to each node, thereby also reducing installation and infrastructure costs. The Easy Way to Bluetooth 4.0 Implementation Product developers are already getting to grips with the new Bluetooth 4.0 wireless standard. As markets for these new devices become established, and as further new application opportunities emerge, they will need to be able to add Bluetooth 4.0 capabilities to new products without becoming involved in low-level implementation challenges such as analogue and RF design, integrating the various required protocols, and implementing the host-controller interface supporting connection to the main application processor. Frequently, product development teams are focused at the application level and do not have in house expertise to complete these tasks. To overcome these barriers the organisation may choose to acquire the needed expertise organically or hire a consultant. In either case, this can add to development costs and delay market introduction. In the Bluetooth space, there is a precedent for semiconductor vendors to offer a system-on-chip solution that builds in solutions to most or all of these challenges. One such vendor is Toshiba Electronics, which is a founding member of the Bluetooth SIG and has been involved in Bluetooth standardisation and implementation for more than a decade. The company has already delivered a number of Bluetooth LSI solutions to the market, which support the version 2.1 and 3.0+ Enhanced Data Rate (EDR) standards. These include the TC35655 single-chip CMOS IC with embedded ARM9 application processor, which supports Bluetooth profiles such as Hands-free and Audio Streaming and is used in the automotive space. . To help speed up time to market and cut development costs for emerging generations of Bluetooth 4.0 products including LE technology, Toshiba has developed the TC35661. This new device supports Bluetooth 4.0 covering Bluetooth Classic (3.0) and Bluetooth Low Energy (BLE), enabling use in single-mode or dual-mode applications. It is fabricated using 65nm RFCMOS technology, which delivers die-size advantages, and features internal voltage management contributing to low overall power consumption and a minimum of external passive components. A 30µA sniff mode also helps to minimise overall energy budget ultimately resulting in longer battery life. The TC35661 RF block offers a robust sensitivity of -91dBm. The device also provides a high level of integration (figure 2), with features such as an LDO regulator and all of the necessary RF functionality including a balun, antenna switch and LNA implemented on-chip. An ARM core with onboard ROM and SRAM handles Bluetooth protocol and data processing tasks at various speeds. Interface options include UART and USB to connect to a host CPU, and SPI, I2C, I2S/PCM. Support for IEEE 802.15.2 2/3/4 wire coexistence is also provided. Finally a set of general purpose IOs are available for controlling various embedded functions. Figure 2. Block diagram of TC35661 Bluetooth 4.0-compliant SoC. Figure 3. TC35661 and standard Bluetooth HCI communication. The TC35661 is - in combination with standard GATT profiles for BLE and HDP profile for BT classic - suitable for use in medical, consumer and automotive applications. In order to cope with quality requirements of the automotive market, the TC35661 can follow the AECQ100 quality standard. The device can be used with the standard Bluetooth HCI UART host-controller interface. Alternatively Toshiba can provide a fully integrated Bluetooth stack with a selection of application profiles, which enables a complete Bluetooth solution without support from an external host. Figure 3 illustrates standard HCI communications with a host processor. In order to simplify the design efforts for OEMs and free them from complex interoperability tasks, Toshiba offers a Bluetooth certified protocol stack, which can be combined with its various Application Profiles depending on the target application type. Figure 4 shows an overview of BT 3.0 profiles that can be run with TC35655. An open API is available and a flexible integration into various OS is achievable. A subset of these profiles can be run within the TC35661. Figure 4. Bluetooth Classic software configuration. A further step to simplifying Bluetooth system design is the complete software integration model for BLE or Bluetooth classic. Figure 5 shows an example of an embedded system software architecture for BLE. It is also possible to achieve a dual mode architecture (classic + BLE) by embedding the related stack and profiles onto the TC35661. This can serve the legacy Bluetooth as well as the new BLE standard. Figure 5. Bluetooth BLE software configuration embedded into TC35661. The Bluetooth SIG describes Bluetooth Dual mode solutions as “Smart Ready”, and Bluetooth BLE only solutions are called “Smart”. Suppliers may tag such products accordingly. To assist designers further and speed up time to market for new LE and dual-mode applications, the supporting evaluation board or USB sticks, and PC-based tools enable developers to exercise the full functionality of the device, configure parameters, and monitor trace data to verify operation of the HCI or API (figure 6). Figure 6. Configuring the TC35661 evaluation board. Conclusion Since its arrival in the wireless networking marketplace, Bluetooth has been enthusiastically adopted within a relatively small world of applications. With the arrival of the version 4.0 standard adding LE technology, and new system-on-chip devices supporting this enhanced functionality, Bluetooth will open up a much wider universe of applications based on smart, low-power devices. ## For more product information visit http://www.toshiba-components.com/wireless/index.html or our Toshiba Electronics Europe's web site at www.toshiba-components.com Contact details: Toshiba Electronics Europe, Hansaallee 181, D-40549 Düsseldorf, Germany Tel: +49 (0) 211 5296 0 Fax: +49 (0) 211 5296 792197 Web: http://www.toshiba-components.com E-mail: Wireless: [email protected] About Toshiba Toshiba Electronics Europe (TEE) is the European electronic components business of Toshiba Corporation, which is ranked among the worldʼs largest semiconductor vendors. TEE offers one of the industry's broadest IC and discrete product lines including high-end memory, microcontrollers, ASICs, ASSPs and display products for automotive, multimedia, industrial, telecoms and networking applications. The company also has a wide range of power semiconductor solutions as well as storage products like HDDs, SSDs, SD Cards and USB sticks. TEE was formed in 1973 in Neuss, Germany, providing design, manufacturing, marketing and sales and now has headquarters in Düsseldorf, Germany, with subsidiaries in France, Italy, Spain, Sweden and the United Kingdom. TEE employs approximately 300 people in Europe. Company president is Mr. Takashi Nagasawa. Toshiba Corporation is a world-leading diversified manufacturer, solutions provider and marketer of advanced electronic and electrical products and systems. Toshiba Group brings innovation and imagination to a wide range of businesses: digital products, including LCD TVs, notebook PCs, retail solutions and MFPs; electronic devices, including semiconductors, storage products and materials; industrial and social infrastructure systems, including power generation systems, smart community solutions, medical systems and escalators & elevators; and home appliances. Toshiba was founded in 1875, and today operates a global network of more than 550 consolidated companies, with 202,000 employees worldwide and annual sales surpassing US$74 billion. For more company information visit Toshiba's web site at www.toshiba-components.com Ref: TWP09/D3