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1 OCTOBER 06 THE WIRELESS QUARTER In this issue u Wireless marine safety WIBREE Nordic is one of the first members in Nokia s Wibree open initiative p Geir Langeland u 2.4-GHz RFID reader and tag sensors p Managing interference in crowded gyms u Nordic in the press p People & faces } Nordic Semiconductor has become a member of the open Wibree industry initiative that is designed to extend local wireless connectivity to small, batterypowered peripheral devices by consuming only a fraction of the power of existing technologies while supporting very low cost implementations. Wibree is the first open wireless technology to specifically target connectivity between mobile devices such as smartphones or PCs and small, battery-powered devices such as watches, wireless keyboards, toys and sports sensors. Indeed the list of potential applications and battery-powered peripherals that could now enjoy the benefit of the wireless revolution will only be limited by the imagination of designers, comments Nordic s CEO, Svenn- Tore Larsen. As such, we believe the growth potential for Wibree will be truly enormous because the market continually reminds wireless companies like ourselves that consumers don t like wires and always respond positively when a product or application is made wireless without a significant cost or inconvenience penalty such as the need for frequent battery recharging cycles. Wibree, therefore, is what consumers of compact, portable electronics devices of which the mobile phone is the perfect example have been crying out for. It will dramatically extend the wireless functionality and allow PCs and portable devices to interface wirelessly to a huge range of peripherals such as sports and health sensors. Nordic Semiconductor Product Manger, Thomas Embla Bonnerud, adds: The technical challenge is to ensure minimal power consumption under heavy, daily usage. Wibree is the first technology that combines interoperability and a lightweight protocol stack specifically designed for ultra-low power implementations. This is a field in which Nordic Semiconductor is now generally regarded as a global leader and is why we as a company are a totally committed partner in enabling this new exciting market for wireless communication and to playing our part in making Wibree happen. For further information please visit Nordic s dedicated Wibree website at This site will be continually updated with new information about Wibree as and when it becomes available, as soon as it becomes available. Wibree is the very first open wireless technology to target small, battery-powered devices such as watches, keyboards, toys and sports sensors WELCOME TO THE WIRELESS QUARTER This is the second issue of Nordic s new quarterly newsletter. It is designed to keep you updated on the latest news and developments at Nordic and is supplied free-of-charge. Next issue out January 07. PLEASE FORWARD THIS NEWSLETTER TO ANY COLLEAGUES OR CUSTOMERS WHO MAY FIND IT USEFUL To subscribe (or un-subscribe) please news@nordicsemi.no

2 MARINE SAFETY Dear Reader, I am pleased to introduce the second issue of Nordic Semiconductor s The Wireless Quarter. In this issue our front cover is devoted to Nordic s proud and deep involvement with the brand new open Wibree industry initiative from Nokia, and we also highlight successful products based on our nrf24ap1, nrf24l01 and nrf9e5 transceivers. Both Wibree and our continuing range of ultra-low power proprietary architectures will ensure that Nordic helps its customers build 2.4-GHz wireless products that run far longer on batteries than any competing technology. The nrf24ap1 uses Dynastream s ANT protocol. This protocol is ideally suited to very low-power star-topology applications, easily outperforming ZigBee for low node count networks. Dynastream is a Nordic partner and the company s protocol ideally matches the nrf24ap1 s hardware. It provides designers with the flexibility to tailor the wireless design to their application in a way that s just not possible with standards-based protocols. You ll find more information about the ANT protocol in this issue in an application article from Dynastream s James Fujimoto on pages 4 and 5. And we plan to feature items on ANT regularly in future issues of The Wireless Quarter. In the last few months we have continued to expand our sales and support structure, particularly in Asia and Japan. Asia is an important market for Nordic and we are continually amazed at the ingenuity of the region s engineers. In our Hong Kong office we welcome John So, a Field Applications Engineer who is ably supporting our Greater China Regional Sales Manager Chim Chan, and, perhaps more importantly, the customers who are striving to produce winning designs incorporating Nordic Semiconductor transceivers. In South Korea, Sean Choi joins the company as the country s Regional Sales Manager. Sean has enjoyed some early success already: Incheon-based Chois Technology has selected the nrf24l01 to form the wireless link between its X-Presenter remote presentation device and a PC (see page 3). While in Japan, we have opened a dedicated office in Tokyo and appointed Nori Shibuya as the Regional Sales Manager for Japan. Japan is an extremely competitive market for Nordic and we are working hard to establish our name and presence there. Finally, may I direct all readers to Nordic s brand new, 100 % Wibree website at and encourage them to register their address for regular updates via the receive more Wibree news link at the bottom of the home page. We aim to make this the No. 1 online source of technical design information for Wibree bar none. Yours sincerely, Geir Langeland Sales & Marketing Director We aim to make our new, 100 % Wibree website the No. 1 online source of technical design information for Wibree bar none Geir Langeland The CoastKey stops boats powering off to leave victims stranded after falling overboard The world s first electronic boat engine kill switch uses nrf9e5 } Norwegian marine safety specialist, Wireless-Safety, has deployed the Nordic Semiconductor nrf9e5 family of highly integrated 433/868/915- MHz transceivers into the world s first ever, electronic wireless boat engine remote control, the CoastKey ( CoastKey is a wireless remote control with a range of up to 10 meters that acts as an in-dock immobiliser, engine start/stop remote controller and remote engine tilter (to lift or lower the power unit from/into the water). The unit also performs a crucial safety function by acting as an engine kill switch, worn round the pilot s neck, that switches off the engine within two seconds of the pilot falling into the water and activates a high intensity flashing light on the CoastKey to aid recovery in darkness. Traditional engine kill switches are mechanical, using a tether between the boat ignition key and the pilot. If the pilot falls overboard the tether pulls the key from the ignition and stops the engine. However, the system is abused because pilots often forget to attach the tether. CoastKey s wireless connection eliminates the tether and because the device also acts as the engine start switch/immobiliser, the pilot always carries it. CoastKey communicates with a Nordic transceiver on the boat once per second. In the event of the pilot falling overboard the signal is interrupted. After a one-second interval without a response the electronics on the boat stops the engine. Previous attempts to develop wireless engine kill switches for marine use proved difficult because of electromagnetic interference (EMI) from the engine, compounded by the sea acting as a reflector for ambient EMI. This hostile radio environment constantly interfered with the signal, breaking the radio link and prematurely activating the kill switch. Wireless-Safety has resolved the challenge for the first time by combining an nrf9e5 physical layer with the company s own frequency hopping algorithm. Now, if the transceiver detects interference it rapidly switches to a clear channel. Wireless-Safety says it selected the Nordic Semiconductor nrf9e5 for the CoastKey application for three reasons: First, the RF system-on-chip includes an 8051-compatible on-board microcontroller (MCU) plus all inductors and filters. Second, the nrf9e5 s low current consumption means that at an average usage of 50 active hours per year the CoastKey s 400-hour real world battery life (when natural battery discharge and aging are factored in) gives a typical 3 to 5-year service before its batteries need to be replaced or a new CoastKey purchased. Finally, Nordic Semiconductor s ShockBurst transmission technology allowed Wireless- Safety to optimise the power consumption by allowing the transceiver to spend most of its time in an ultra-low power sleep mode before periodically waking to transmit for a short period before returning back to sleep. 2 NORDIC WIRELESS QUARTER OCTOBER 2006

3 NEWS PC CONTROLLER & LASER PRESENTER South Korean Chois Technology selects nrf24l01 for its X-Pointer II presenter } South Korean firm Chois Technology, based in Incheon, has selected the nrf24l01 ultralow power, fully integrated 2.4- GHz transceiver for its X-Pointer II wireless remote presenter and mouse product. The X-Pointer II combines a remote slide presenter, wireless mouse, built-in laser pointer, and a USB flash drive of either 256- or 512-MByte capacity. The nrf24l01 transceiver operates in the global 2.4-GHz ISM band and endows the X-Pointer II with a range of up to 50 m and provides a reliable link even when obstructions such as desks and people are between the remote presenter and a laptop PC. This is an advantage compared to infrared (IR) remote presenters which must establish a line-of-sight connection with the PC to operate. The nrf24l01 features Gaussian Frequency Shift Keying (GFSK). Should interference on the transmission channel be detected, this spread spectrum technique allows the transceiver to hop between multiple channels 31 in the case of Chois Technology s application in just 130 µs per hop. This makes the nrf24l01 highly QUICK REFERENCE BOX: nrf24l GHz RFID reader and tag sensors that can run for 5 years from 3-V coin cell } Swedish Bluetooth and RFID specialist, Free2move, has selected the Nordic nrf2401a for use in its newly launched 2.4-GHz active RFID products. These have a reader-to-tag range of up 70 m and include Free2move s Long Life Tag that can run for 5 years or more from a single CR V lithium coin cell commonly used in products like wristwatches. (This compares with typical battery life of one year for Free2move s immune to communication link breakdown in the busy 2.4- GHz spectrum. In addition, the X-Pointer II features impressive battery life. For example, when using the remote presenter and mouse keys KEY FEATURES: True single chip, 2.4-GHz GFSK transceiver Complete OSI link layer in hardware 1.9 to 3.6 V single supply 20-pin QFN20 (4 x 4 mm) package ShockBurst TM and MultiCeiver TM technology Auto acknowledgement and retransmit 80 channel frequency hopping/130 µs switching 40 bit address support and 16 bit CRC 900 na built-in power down mode TX dbm output RX Mbit/s Uses low cost ±60 ppm crystal and inductors 1 to 2 Mbit/s on air data rate RADIO FREQUENCY IDENTIFICATION existing tags.) Although Free2move s specialty is Bluetooth, the company s cofounder and product manager, Dan Hellgren commented: We found that building a commercially viable RFID system that can read up to 300 fast moving tags per second with Bluetooth was impossible. The problem is that while Bluetooth is good for high-speed data comms between devices such as a mobile (but not the laser pointer) the unit will run continuously for up to 100 hours on a pair of standard AAA cells. This performance relies heavily on the ultra-low power characteristics of the nrf24l01 transceiver (see Quick Reference Box below). The nrf24l01 extends battery life by between 15 and 600x compared with other 2.4-GHz technologies such as Bluetooth. PRIME APPLICATIONS: Wireless mice, keyboards, joysticks Intelligent sports instruments Industrial sensors Keyless entry Wireless data comms Alarm, security and surveillance systems Home automation Automotive Telemetry Toys phone and PC, it consumes too much power for heavy duty-cycle applications like RFID. Bluetooth also has a rather sluggish communication latency that isn t suited to rapid detection of fast moving goods and objects. IN BRIEF nrf2401a employed in Suunto s latest t-series Suunto has specified the ultralow power, 2.4-GHz nrf2401a in conjunction with Dynastream s ANT protocol in its brand new watchbased Suunto t3 and t4 heart rate monitors; Suunto Road Bike, New Bike and GPS POD sensors; and PC POD peripheral observation device. The Suunto t3 and t4 are scaled down versions of the high-end t6, and the new wireless sensor accessories allow the watches to record and analyse live training data. New regional sales office established in Tokyo Nordic Semiconductor has opened its first Japanese regional sales office in Tokyo and appointed Nori Shibuya as regional sales manager. The office at Minato-Ku (Phone: ) will offer customers technical and commercial support plus application-specific design guidance. This office reflects the importance we are placing on the Japanese market and it will enable Nordic to provide more focused, localised support to both our existing distributors in Japan, says Shibuya. Wireless audio module gives access to high end RF Arrays has launched a set of three modules based on the nrf24z1 designed to eliminate the cost and complexity of adding top quality wireless audio to almost any product (e.g. MP3 player headphones, PC and home cinema satellite speakers). The modules comprise two transmitter modules; a USB transmitter in memory stick form factor for PCs; and an analogue transmitter with inputs from an RCA or headphone jack audio source along with a speaker/ headphone receiver module. NORDIC WIRELESS QUARTER OCTOBER

4 ULTRA-LOW POWER NETWORKS Managing interference in crowded 2.4-GHz radio band environments While spread spectrum techniques such as adaptive frequency hopping work well, other interference avoidance methods are more efficient in congested 2.4-GHz environments like gyms, as James Fujimoto of Dynastream explains While several ISM bands are available, only one the 2.4- GHz band is accepted virtually globally. This makes it the perfect choice for manufacturers exporting products worldwide. Many standards-based radios for example IEEE.802.xx compliant products such as Wi-Fi, Bluetooth and ZigBee as well as proprietary forms of wireless Ethernet and wireless USB, all use the 2.4-GHz band. This means that chief among the technical challenges of deploying 2.4-GHz radios is ensuring that the radio link is able to handle the inevitable interference in what is becoming a very crowded band. In fact, regulations governing the ISM parts of the spectrum state that a device must expect interference. My company, Dynastream Innovations, and our partner Nordic Semiconductor are no exceptions. Nordic designs a 2.4- GHz silicon radio, the nrf24ap1, which incorporates the ANT wireless personal area network protocol. This combination is ideal for ultra-low power wireless links comprising sensors and transceivers that can run for years without any need for battery replacement. Designers of low-power radios have come up with some innovative methods to avoid interference using a combination of modulation and channel management techniques. The most notable methods of channel management are Time Domain Multiple Access (TDMA), Frequency Hopping (FH) and Direct Sequence Spread Spectrum (DSSS, also known as DS-CDMA). These channel management methods are combined with various modulation techniques such as Gaussian Frequency Shift Keying (GFSK) and Frequency Shift Keying (FSK) to enable a variety of solutions with different strengths to best address the application requirements. TDMA channel management works by subdividing the communication frequency into a number of timeslots allowing several users to share the same frequency. Each transceiver waits for its own timeslot before transmitting, thus avoiding interference. We ll talk about TDMA in more detail below, as it s the basis for the nrf24ap1/ant interference avoidance technique. DSSS modulation and channel management transmissions multiply the data being transmitted by a noise component. This noise signal is a pseudorandom sequence of values, at a frequency much higher than that of the original 2.4-GHz signal, thereby spreading the energy of the original signal across a much wider band. The noise is filtered out at the receiving end to recover the original data, by again multiplying the same pseudorandom sequence by the received signal. For recovery to work correctly, transmit and receive sequences must be synchronised. This requires the receiver to synchronise its sequence with the transmitter s sequence via some sort of timing search process. DSSS works at a cost of transmitting excessive data packets, incurring both bandwidth usage and current consumption overheads. Bluetooth and Nordic products, including the nrf24ap1, use the GFSK modulation technique. This technique results in a dampened or gentler frequency swing between the high ( 1 ) and low ( 0 ) levels. The result is a narrower and cleaner spectrum for the transmitted signal compared with FSK. Bluetooth manages interference through the combination of GFSK modulation and FH. Bluetooth splits the 2.4-GHz ISM band into 79, 1-MHz channels (with a 1-MHz guard channel at the lower end of the band and a 2-MHz guard channel at the higher Concept2 has recently selected the nrf24ap1 with Dynastream s ANT protocol for built-in heart rate monitoring on its latest Model E rowing machine 4 NORDIC WIRELESS QUARTER OCTOBER 2006

5 APPLICATION NOTE end). Bluetooth 1.2 uses a revised form of frequency hopping dubbed Adaptive Frequency Hopping (AFH). This algorithm allows Bluetooth devices to mark channels as good, bad, or unknown. Bad channels in the frequency-hopping pattern are then replaced with good channels via a look-up table. With FH, a wireless technology transmits on a clear channel until it experiences interference (resulting in lost packets), whereby it relocates to a clear channel. Alternatively, the transmitter can periodically pseudorandomly retune to a different channel to minimise the chances of encountering interference that could occur when transmitting on a single channel for long periods. Unfortunately, while Bluetooth includes this provision for interference management, there is little flexibility for the designer beyond what the architects of the standard have provided. In contrast, Nordic Semiconductor s nrf24ap1 allows the designer to benefit from interference management using GFSK modulation and TDMA channel management, but also permits the simultaneous use of frequency hopping for the ultimate flexibility in interference management. The Bluetooth AFH system works well when it experiences interference from other radio sources, for example Wi-Fi (typically used for Wireless LANs or WLANs) because it simply hops to an alternative channel. But when there are dozens, or even hundreds of competing sources AFH has its weaknesses. For example, there are only 79 channels, Nordic s nrf24ap1 with Dynastream s ANT protocol offers an optimised ultra-low power solution for low duty cycle applications so only a relatively limited number of competing sources can be accommodated. Another issue is hopping between channels typically occurs when interference has been detected; this inevitably means unacknowledged packets will need to be retransmitted once the channel has been changed, consuming bandwidth, increasing power consumption and shortening battery life. This is the main reason why wireless links in the lab often exhibit much greater data transfer rates than those used in real world, practical situations. In contrast to Bluetooth, the nrf24ap1 uses a TDMA scheme. The nrf24ap1 has been specifically designed as an ultralow power consumption radio with a built-in protocol solution. It is targeted at applications where batteries have to last for years, or even for the entire life of the product. Embedded with the ANT protocol, the nrf24ap1 is ideal for applications such as heart rate monitors communicating with intelligent sports watches, or large numbers of temperature sensors embedded in the ceiling of an office building or warehouse all communicating with a transceiver elsewhere in a given room or area. For these kinds of applications there are often dozens, or even hundreds of sensors attempting to transmit information on the same frequency in a physically confined space. This isn t a co-existence that engineers typically consider. They mainly think of one wireless technology comfortably existing alongside another wireless technology. Rarely does the application designer think about similar types of sensors close together doing the same thing and having to work correctly in a small enclosed area. Let s consider an example. A large, commercial gym could have 30 or 40 rowing machines side-by-side. Many of the machine users may be wearing heart rate monitoring belts transmitting to their sports watches on the 2.4-GHz frequency band. If Bluetooth was chosen to power the wireless links, its greater radio on-air time required to manage interference and accommodate the larger message overhead would quickly consume a standard coin-cell battery, the preferred choice of battery used to power these devices. The nrf24ap1 transceiver embedded with ANT, however, is ideally suited to this application. Heart rate monitoring (HRM) is a low duty-cycle task that requires a wireless solution with an ultra-low current sleep mode that quickly comes to life periodically for a burst of information before going back into sleep mode again. The nrf24ap1 is optimised for just this type of operation offering typical HRM battery lifetimes of approximately 3 years on a CR2032 coin cell battery with 1 hour per day usage. The nrf24ap1 s TDMA collision avoidance approach relies on each transceiver transmitting in a clear timeslot. If there are a number of discrete systems working sideby-side such as the rowing machines in our gym example by listening for drifting transmission sources on its frequency the wireless node can determine if there is approaching interference. It can then adapt its transmissions accordingly even if there are dozens of competing RF sources. James Fujimoto is ANT Product Manager with Dynastream Innovations Inc. For more information on the ANT protocol go to A large, commercial gym could have 30 or 40 rowing machines side-by-side. Many machine users may be wearing heart rate belts transmitting to their sports watches on the 2.4-GHz band NORDIC WIRELESS QUARTER OCTOBER

6 EE TIMES CHINA PORTABLE EQUIPMENT SUPPLEMENT Adding a wireless link: The design challenges Recently, Chim Chan, Nordic s Greater China Regional Sales Manager for Hong Kong, China and Taiwan was interviewed by EE Times China. Here s an edited excerpt The full version of this article was published in a supplement to EE Times China that is circulated to 66,000 readers in mainland China, Taiwan, South Korea and member countries of the Association of Southeast Asian Nations (ASEAN) 1. Jon Adams, Director of Wireless Technology and Strategy at Freescale Semiconductor. Blog, May 16, 2006, CMP s Wireless Net Design Line. EE Times China (EETC): What are the design challenges of adding wireless functions to portable devices? Chim Chan (CC): Adding a wireless link to portable devices presents four key design challenges: cost, complexity, power and size. Many designers are wary of adding wireless functionality because they perceive it to be complex. After all, silicon radios feature RF, analogue and digital functions and are complicated products. However, most silicon radio vendors have produced integrated transceivers that make the process somewhat easier. But it s still not simply a case of dropping a chipset onto the PCB though; you have to be aware of issues such as antennae positioning, range and interference with other devices. While standards such as IEEE802.xx are good for ensuring interoperability, this does extend time-to-market because you have to ratify your wireless link to the standard adding to non-recurring engineering (NRE) overheads too. In peer-to-peer applications proprietary radios such as Nordic s nrf24xx range perform better than Bluetooth yet don t have to adhere to a standard (but of course do have to comply with local RF regulations). As a designer it s easy to lose sight of this fact among the Bluetooth hype. Power is also a major issue. Consumers want cellphones and MP3 players with batteries that last tens of hours at least. That means the radio has to be very efficient. Bluetooth 1.2 chips and even the latest 2.0+EDR devices are not the most economic devices. Nordic Semiconductor s chips have been specifically designed to run at ultra-low power and typically exhibit twice the battery life compared with Bluetooth in an identical application, but with the same (or better) bandwidth and range. Finally, designers are under a lot of pressure to shrink the electronics to fit the compact profile demanded by consumers of mobile devices. While most silicon radio vendors have done a pretty good job of integration, the chips tend to demand some form of supervisory microcontroller (MCU) and an array of support components. In contrast, Nordic s nrf24xx transceivers measure just 6 by 6 millimetres, and integrate the RF transceiver, an 8051 MCU, 4-channel, 12 bit ADC and various standard interfaces. EETC: What new product or technology are you developing to address the design challenges? CC: Nordic s transceivers are integrated and compact, relatively simple to design-in, use an efficient protocol, are extremely power frugal and feature adaptive frequency hopping. And our devices can deliver up to 4 Mbit/s, something that not even Bluetooth 2.0+EDR can achieve (it s rated at a nominal 3 Mbit/s). By specialising and not being constrained by the requirements of a standard we have been free to design an excellent silicon radio. For example, our nrf24l01 is an ultra low-power device that suits applications like wireless mice where power consumption is the primary challenge (because the device is always on) and bandwidth is secondary. Alternatively, our nrf24z1 is a high bandwidth device specially designed for Nordic s nrf24l01 is an ultra low-power device that suits applications like wireless mice where power consumption is the primary challenge wireless audio streaming between (e.g.) an MP3 player and wireless headphones. At 4 Mbit/s it is able to transmit uncompressed (i.e. genuine) CD quality audio. EETC: How do you help designers decrease the power consumption of a wireless link? CC: Nordic s designs have been enhanced and optimised over many years, specifically for lower power consumption, and we are constantly refining the silicon to make it even more efficient. In contrast, Bluetooth and ZigBee are constrained by the requirements of their respective protocols, so there is little that can be done to lower the power consumption. For example, a typical transmitting or receiving BT 1.2 radio chip runs at around 60 ma average current consumption (some manufacturers products are more efficient). In comparison, the nrf24z1 s average transmit current is 17.8 ma and the average receive current is 22.9 ma while transmitting and receiving a 44.1-kHz sampled, 16-bit audio stream without compression and a good radio link. EETC: Could you forecast the wireless design trend in portable devices? CC: We can only see rapid growth because consumers don t like wires and value the convenience and freedom that wireless brings. We believe Bluetooth has done an excellent job in educating consumers about the benefits of wireless, but that it is a compromised technology that restrains designers. I totally agree with a comment from a top RF radio design guru who said even some members of the Bluetooth Special Interest Group (SIG) believed: Bluetooth bears more than a few resemblances to another once-vaunted and highly deployed technology IRDA; Great while it lasted, useful for a few techies, but ultimately dying a lonely, quiet death. 1 TO SEE ORIGINAL ARTICLE GO TO: (The article is in Simplified Chinese) 6 NORDIC WIRELESS QUARTER OCTOBER 2006

7 PRESS ARTICLES CHINA MEDICAL DEVICE MANUFACTURER A proprietary approach to powering medical RF links Proprietary RF technology can add wireless capability to medical devices without the overhead of standardsbased approaches, as Torstein Heggebø explains The full version of this article was originally published in the July issue of China Medical Device Manufacturer (CMDM). The magazine is published in Simplified Chinese and is circulated in mainland China to over 5,000 medical technologists Portable instruments such as blood-pressure monitors, pulse oximeters, spirometers, and heartrate monitors are among the most fundamental tools of a doctor s trade in intensive care. Because the sensors for these instruments are typically attached to the patient by wires, however, they tether the patient to the bed. Moreover, moving the patient becomes awkward because all the instrumentation has to be disconnected and later reconnected. Low-power, low-cost wireless technology can eliminate these problems. At first glance, IEEE x standards-based RF wireless technologies such as Bluetooth or its lower-powered cousin ZigBee would appear to be the obvious choice to bring this functionality to medical equipment. But other non-standard wireless alternatives deserve consideration. These can offer superior integration thus lower cost, reduced power consumption and a simplified architecture. Measuring blood-oxygen levels Pulse oximeters are typical examples of the monitoring equipment used for intensive care. They measure blood-oxygen level and pulse rate non-invasively by a clip attached to a patient s finger or earlobe. The clip contains a photo detector and two light emitting diodes (LEDs) see picture above. The red and infrared LEDs of the sensor typically draw 10 ma or less and are activated for 50 µs or less for each measurement. At this sampling rate, with 50-µs LED activation time per sample, each LED has a duty cycle of 1.5%. The average current consumption for the two LEDs is then: 2 x 10 ma x 1.5% = 0.3 ma. The other components of the sensor consume little power compared with the two LEDs, and can thus be ignored here. The oximeter s 300 samples/s correspond to one measurement every 3.3 ms. To be A wireless link can replace the cable shown for attaching pulse oximeters to displays able to update a remote display in real time (to the human eye) and assuming a transmission latency of 30 ms, it is possible to carry 10 measurements in each transmitted package across a wireless link. Each wavelength measurement takes 8 bits of data, totalling 16 bits for both the red and IR bands. The payload of each transmitted package with 10 samples then becomes 160 bits. Comparing 2.4-GHz protocols The Bluetooth protocol maintains synchronisation between paired devices by sending a packet every other 675 µs time slot (equating to 800 packets/s) to maintain the link, significantly increasing the duty cycle. Bluetooth also supports three low power modes during which synchronisation is maintained: park, sniff, and hold modes. If this synchronisation is not maintained, reacquisition is needed, which can take up to 3 seconds. This synchronisation requirement reduces battery life because, although the synchronisation packages are short, the high number of transmissions (800 transmissions/s for Bluetooth versus 30 packets/s for the Nordic solution) significantly increases the duty cycle. By contrast, ZigBee was designed with low power in mind and is thus endowed with a simplified protocol to reduce the packet overhead. The Nordic Semiconductor solution has also been specifically designed to be economical with batteries. In both cases, the key to this low-power consumption is minimising the duty cycle so that the radio is in standby mode for as long as possible. The sequence diagram for the Nordic device shows that the radio system of the device has to be active for about = 752 µs for each acknowledged packet. This corresponds to an active duty cycle of approximately 2%. The Nordic transceiver consumes less than 20 ma when active, and 12 µa when in stand-by mode. The average current consumption of the radio and the microcontroller then becomes approximately (ignoring the negligible standby current): 20 ma x 2% = 0.4 ma. For the ZigBee solution, the device is active for = 2392 µs per acknowledged packet. This corresponds to an active duty cycle of approximately 7%. Assuming the ZigBee chip s average current consumption is similar to that of the Nordic device, this will be approximately 20 ma x 7% = 1.4 ma for this example. Consequently, in the pulse oximeter the simple Nordic protocol will consume one-third of the transmission power of a ZigBee solution. For the ZigBee solution, the power consumption required for the RF link dominates, and for the Nordic protocol the power consumption for the sensor and the RF link are in balance. The Nordic solution could run continuously for more than a week on a small 200-mAh battery; a ZigBee solution would run less than half that time, or require a battery twice the size. TO SEE THE ORIGINAL ARTICLE GO TO: NORDIC WIRELESS QUARTER OCTOBER

8 THE PEOPLE & FACES Behind Nordic Semiconductor Lars Sundell Designer & Project Manager, Mixed Signal ASIC An organisational culture of pulling together when things get technologically difficult is what ensures deadlines are hit. It s one of the things I really like about Nordic Semiconductor Hi. My name is Lars Sundell and I m a Designer & Project Manager based in Oslo. I joined Nordic Semiconductor in January 1999 as an analogue designer but quickly found myself being pulled heavily into the digital domain as well. There were several reasons for this. The most important was my strong interest in both analogue and digital design. When I was a student, for example, I went to both digital and analogue classes and resisted the temptation to specialise in one or the other like many engineers. So later, the opportunity to use and widen my knowledge in both these fields at Nordic was both ideal for me and extremely useful when working on the system specification of our products. Over the last 4 years, however, I have progressed into project management on customer specific ASICs and the development of our standard RF chips. My main responsibility is to ensure projects stay on target even when the solutions may not be well defined from initial specification through design and verification and then finally into volume production. Up until recently I have worked on customer specific projects, but with the recent company-wide decision to further strengthen our focus on standard components, my work has also shifted accordingly. One of the things I really like about my job is the varied work and the fact that no two projects are ever the same which keeps it interesting. I also like having visibility and involvement with the complete design flow from specification to production. You get to see a real, physical result at the end of all the hard work that you can be proud of when you see it working in a commercial product or application. That said, there are always new technological challenges to be solved and the opportunities for continuous improvement and enhancement of existing solutions nothing ever stands still at Nordic. Without the support and enthusiasm of my colleagues, however, and an organisational culture of pulling together when things get technologically difficult to ensure deadlines are hit none of this would be possible. It s one of the things I really like about Nordic Semiconductor as a company. Outside of work my life currently centres on my wife and two-year old son. Unlike some of the other Nordic people in People & Faces, I can t claim that I presently undertake that many wonderful or exciting non-professional passions beyond being fully engaged in renovating our family home. That said, as any of you will know who have done this, it feels like a second career at times. Lars Sundell With increasing functionality and ever decreasing amounts of on-chip space, ensuring Nordic s chips are testable in production is challenging Linda Kristoffersen Senior Test Engineer Hi. My name is Linda Kristoffersen and for the past 10 years I have worked as a Senior Test Engineer in Trondheim for Nordic Semiconductor. A big part of my job is ensuring Nordic chips from high volume standard RF components to more specialised Systemon-Chip (SoC) products are fully testable in production and meet strict quality standards. This includes planning the required Design-For-Test (DFT) for each device; designing the different test structures (e.g. test controllers and BIST modules); creating test patterns (including verification and hand-over to the production test house); creating the test specification for production test; and supporting the test house during test program implementation. With ever increasingly amounts of on-chip functionality and ever decreasing amounts of on-chip space, this is always a challenging task. With experience, however, it does become easier as you develop instincts for what will and won t work. What I really like about my job is that I get to work at some point with almost everyone in the technical design and development teams and so make a lot of new friends. I also find it really inspiring to work with the designers at Nordic Semiconductor they are so talented yet always have time to help and support anyone who needs it. In fact I think that is one of the best things about working at Nordic the friendly and helpful working environment and the way people pull together as a team to help deal with technological challenges that would otherwise be impossible to solve or even cope with. And when we succeed, we all share in the feeling of accomplishment and success. Outside of work having a family means there isn t a whole lot of time left for me to indulge in any time-consuming hobbies on a daily basis. Like most Norwegians though I do enjoy being out in the forests and hills (particularly lovely around Trondheim), taking long walks in the summer, and skiing in the winter. Growing up on the Norwegian west coast has also left me with a passion for ocean fishing. At home I love to cook and one of my all-time favorite dishes is Bacalao that comprises salted and dried cod prepared in a really hot Spanish dish style, and tastes simply fantastic! Linda Kristoffersen PLEASE FORWARD THIS NEWSLETTER TO ANY COLLEAGUES OR CUSTOMERS WHO MAY FIND IT USEFUL To subscribe (or un-subscribe) please news@nordicsemi.no