Sensor Technology: June, 2014 by EEWeb Magazines

SENSOR Nader Sadrzadeh CEO of Kionix

FUSION INNOVATIONS FROM KIONIX

Navigate Emerging Markets

Smart Sensing with Connectivity Solutions

Projected Capacitance Touchscreens Dominate Consumer Electronics Market

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SENSOR TECHNOLOGY

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CONTENTS

TECH ARTICLE

Projected Capacitance Touchscreens “The primary value proposition of resistive touchscreens is that they are low cost to manufacture. Although resistive touch performance is

COVER INTERVIEW usually limited to basic single

finger touches and gestures, it serves a wide user base.”of NaderstillSadrzadeh, CEO

RESISTIVE TOUCHSCREENS

SENSOR FUSION INNOVATIONS FROM KIONIX

Navigate Emerging Markets Interview with Nader Sadrzadeh CEO of Kionix

ionix is a global microelectromechanical systems (MEMS) inertial sensor manufacturer based in Ithaca, New York. Kionix offers high-performance, low-power accelerometers, gyroscopes, and 6-axis combination sensors plus comprehensive software libraries that support a full range of sensor combinations, operating systems and hardware platforms. Leading consumer, automotive, health and fitness, and industrial companies worldwide use Kionix sensors and total system solutions to enable motion-based functionality in their products.

A major difference between resistive and

projected capacitance touch technology is Kionix touchscreen composition, which significantly

impacts technical functionality and cost. The high transparency and high resistivity properties of indium-tin oxide (ITO) actually were first realized and taken advantage of by resistive touch technology. Resistive touchscreens are constructed of two layers of polyethylene terephthalate (PET) with ITO coated on each layer. The two layers of PET are separated by an air gap and spacer dots. The bottom PET layer is placed on top of an insulating substrate usually made of glass. A protective layer of hard coating is placed on top of the other PET layer. When a finger presses onto the touchscreen, the action causes the top and bottom KX23H ITO layers Accelerome to physically come in contact, which signifies a • Low power : 1μA finger touchdown. Resistive touchscreens 2μA@3.1Hz; are 146 ±2g, 4g, 8g full s available in 4, 5, 6, and 8-wire variants,•which Data Rate 0.781H offer different degrees of durability and• noise • 16-bit resolution suppression.

Key TECH ARTICLEFeatures

ion are l applicat ducts in al ro p s ic possible n Electro ent. This is smart re intellig o m g in b m em edded beco uction of d o tr tivity in ec e n th t, and con thanks to anagemen d m • Low noise with F an al it rs ig so d , sensing Optimizer stems. Sen tronics sy s (MEMS) KX23H MCU Features: ec • Embedded 256el em in st s sy re al ic featu an h • ARM Cortex™-M0 32MHz • Internal voltage ec om mising icroelectr • 128 kB Flash ROM • Embedded wake motion m e most pro th g n • 16 kB SRAM • Digital High-Pas o in lar are am nductors • Power consumption (MCU only): 2.5μA • Integrated Direc in particu in semico th w ro g (sleep); 1.5mA @ 32kHz; 6mA @ 32MHz Tap™ and devic t f marke • I2C master port algorithms sectors o s. • I2C slave port • Excellent Tempe ar ye g t-s the comin smarSurv • 3 GPIO Interrupt capability •m High of aShock ra ag di k oc M R bl l FO ca T pi Ty LA P 1: G re Figu ENSIN SMART-S figure 1 2DH12, LIS TYPICAL eters (LIS latform in p g d n si ce n n se va accelerom tpac g ad o ar r “Sensor fusion al gleSensor fo sm an n si e r o hage of the “quantified self” a ofn9-Axis oTraditional gyros provide excellent performance This is definitelyT the F soluti ALH) inBasics intelligently S344 complete softwareis m shows and the Magnetic Gyro in which people have a growing thirst and important functionality, it is the grathe 1DL, LIhowever, iafrom ntstoaquantify 33 . d IS ge rese h n 3L T H ra combines data repabout and track everything their lives. Combine largest, most expensive and the most power t To accurately represent m s. n en io m at re lic su p eaThis has limited three different sensors ar this with the burgeoning Internet of Things hungry of the three sensor types. g ap individual sensors for sin(IoT), g of m t-seinncommon, 400 ±usage which strives to embed intelligence a gyro’s in many mobile products. Now, an accelerometer, a magn to smar the purpose of improving everyday devices and share the information cks: 6-axis sensors combined with smart- fusion gyroscope. An accelerom lo b n EMS ai application or system m virtually everywhere, and it is evident that software have given product designers a low acceleration and orientat lock, M five b l ta en mto n society is entering a new age of technology power, reduced cost, and sizevi alternative while a magnetometer is performance.”yroscope, ro en e of f ,g thwhich opens up new possibilities th e er e re d driven by the availability of inexpensive and traditional gyros, et earth’s magnetic field and si eg m In d ro le ubiquitous computing and connectivity. At the for the inclusion of gyro-based se functionality n nt the 10 relative to the magnetic EMS: acce M re p n al o re an it ti o rs h ig heart of this trend is data in their n so This article will present the . In sensors ,d , witfor motio • aboutMindividuals and se products. factneeded (LIS3MDL) gyroscopes that measure their surrounding world. The source of this data advantages of integrating 6-axis solutions thatn io er it et s gn m xi co o re output while 9-a sor is sensors, and so the logical extension detect changes pitch, deliver -m otionof 9-axis magisna et 6-axis or in the equivalent r and ainre EMOcapabilities, trend towards ubiquitous sensing. cutting power consumption by as much as6 and improved a trio of and iN 12 900 mba sintelligent 9DS0) f 260thatto percent. It will also illustrate this solution, M le o via0 intelligent sensor LS ab compasse devices has been combined , ge is n S ra H D 6 Sensors are following computing in that using what has been termed as a magnetic e LPS25 (LSM algorithms to provide the foundation d th dule ofusion technology advances are allowing sensors gyro (or MagGyro for only a good n bar,is notan ure awareness.ss These mshort), inertial m for motion and orientation 0.0to20 or positio sors: pre to become smaller and more mobile. In alternative traditional gyros, but can be used to devices—a 3-axis 3-axis enaccelerometer, S l ta ermine flo en et d d nm magnetometer, and 3-axis gyroscope—are addition to the smartphone, newer quantified augment and calibrate traditional gyros. ro an rs h vi e it so n d n E w tu y se alti self- devices are taking the• form of health idit united as a 9-axis inertial measurement unit combined hum wer urethat&provides and fitness monitors, headsets and helmets, functions and features low-po n. 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IHS Electronics & Media has that deliver ty: 9-axis vi ti ec n n forecasted that the performance-monitoring as a valuable and enabling design option for • Co net offers fou theroriginal market will reach $2.3 billion in 2017 and that, Hz, Emarket consumer equipment vity block mity, b 1 Gelectronics LE), sumanufacturers cumulatively, over 250 million of these(B devices (OEMs). These combination e connecti reen, proxi h sc T ch u To will ship between 2012 and 2017. s: products provide es:significant benefits to rfac te e solution manufacturers by • User In consumer-electronics alternativ Innovative microelectromechanical systems reducing overall board space, cost and power y ke (MEMS) inertial-sensor industry suppliers have ch consumption, thus enabling manufacturers to tou nergy (B stepped up to meet growing consumer demand include motion sensors in a greater number and tion ooth low-e for these devices. To support increasingly variety of products. luaet Figure 1: Fusing sensor data traditional 9-axis, 3-sensor solution enables a su Bfrom at the mo cy • A th s enlack. the individual sensors as each sensor compensates for what theeq otheru sensors w o sh fr s consumption. is lupower gyroscope causes the largest increase in cost, The Ma pand ),size,size, dom eNRinGcost, orm analys performance with a substantial and power consumption. (Bludecrease es-of-free s of This platf re te eg ra -d n 9 o a si is ck offers f a 3-axis and transm MEMS blo mposed o WF01SA res odule (SP ng stage co su m si i ea F en m i-s h n W ic o • wh ) moti H EE 80 20 D e t to th IE scope (L3G e of complian imum scal digital gyro GHz w ax 4 m 2. a f h o ss r rate wit frequency ital compa at ig d ge the angula ka -M3, n-pac M Cortex is a system-i STM32 AR res a 3-ax u at ±2000°/s, 4 kB fe h d ic wh ory an 6 ) module to sense Flash Mem nsor able an (LSM303C tr se F n R o ti er ra is w-pow ear accele and a 3-ax • Very lo digital lin (SPIR p to ±8g, u . ct u n ss d o ti au ro G ra p accele nge of 16 GHz band the linear agnetic ra er with a m igital gnetomet e 3-axis d

Smart Sensing with Connectivity Solutions

Kionix CEO: Nader Sadrzadeh Sensing a new future.

PRODUCT HIGHLIGHT

Smart Sensor Hub from Kionix

MagGyro from Kionix Balances Performance with Cost

SENSOR TECHNOLOGY

Projected Capacitance

TOUCHSCREENS

Dominating the Consumer Electronics Market By Chitiz Mathema and Christiana Wu Cypress Semiconductor Corporation

TECH ARTICLE

ouch-enabled devices are now an integral part of our lives, with touch rapidly becoming the user interface of choice. Most touchscreens use either resistive or projected capacitance touch technology. Resistive touchscreens, which allow both finger and non-finger input (e.g., glove, stylus) are used in low-cost smartphones, feature phones, global positioning systems (GPS), printers, and some larger displays. Resistive touchscreens generally support single-finger touch and basic gestures and are cheaper to produce. On the other hand, projected capacitance touchscreens, having superior multi-touch performance, durability, and optical clarity, are usually adopted into high-end smartphones and tablets. Going forward however, projected capacitance is now displacing resistive touch in most small and medium-sized touchscreen devices as well. Moreover, increasing innovation in projected capacitance touch has allowed it to be competitive in price and surpass resistive touch in performance.

SENSOR TECHNOLOGY

â&#x20AC;&#x153;The primary value proposition of resistive touchscreens is that they are low cost to manufacture. Although resistive touch performance is usually limited to basic single finger touches and gestures, it still serves a wide user base.â&#x20AC;?

RESISTIVE TOUCHSCREENS A major difference between resistive and projected capacitance touch technology is touchscreen composition, which significantly impacts technical functionality and cost. The high transparency and high resistivity properties of indium-tin oxide (ITO) actually were first realized and taken advantage of by resistive touch technology. Resistive touchscreens are constructed of two layers of polyethylene terephthalate (PET) with ITO coated on each layer. The two layers of PET are separated by an air gap and spacer dots. The bottom PET layer is placed on top of an insulating substrate usually made of glass. A protective layer of hard coating is placed on top of the other PET layer. When a finger presses onto the touchscreen, the action causes the top and bottom ITO layers to physically come in contact, which signifies a finger touchdown. Resistive touchscreens are available in 4, 5, 6, and 8-wire variants, which offer different degrees of durability and noise suppression.

TECH ARTICLE

Top ITO Layer physically comes in contact with bottom ITO layer on finger press Hard Coat PET Layer ITO Airgap ITO PET Layer Glass substrate Spacer Dots

Resistive touchscreen stack-up

The primary value proposition of resistive touchscreens is that they are low cost to manufacture. Although resistive touch performance is usually limited to basic single finger touches and gestures, it still serves a wide user base. Resistive touchscreens can be found in automotive, medical, and industrial equipment, and of course, point-of-sale (POS) terminals. Resistive touchscreens also continue to dominate applications that require touchscreens greater than 10 inches, since costs for projected capacitance technologies rise exponentially with screen size. Furthermore, some original equipment manufacturers (OEMs) continue to employ resistive touchscreens in low-end smartphones, feature phones, GPS, digital still cameras, and printers with the aim to keep costs low in markets where price competition is severe. Despite the widespread use of resistive touchscreens, there are considerable drawbacks, allowing other touch technologies the chance to establish a presence and expand market share. Users consistently encounter frustration with resistive touchscreens that inaccurately report button activation on a different part

of the touchscreen or not activating presses as intended. Since, resistive touchscreens depend on pressure-activated touch, it requires movement and flexing of the different layers in its stack-up. Moreover, the top hardcoat layer needs to be thin enough to maintain flexibility of the touchscreen panel. The combination of moving layers and a thin protective layer leads to reduced durability and a vulnerability to scratches. Resistive touchscreens also suffer from lower optical transmissivity (< 80%). The construction of resistive touchscreens with two layers of PET, an air gap, and spacer dots can render a loss of refractive and reflective light, thereby yielding a more shaded display. Another negative attribute is that resistive touchscreens suffer from aging, which starts to occur when PET breaks down at high temperature. Signs of aging include touchscreen discoloration, where the touchscreen starts to turn white in color. Resistive touchscreens also have the disadvantage of requiring calibration. Calibration is needed to compensate for ITO sheet resistance drift on PET.

SENSOR TECHNOLOGY

2 Layer

1 Layer

COVER LENS

OCA

PET

Insulator

OCA

GLASS

PET

COVER LENS

OCA ITO

ITO

MH3

ITO

Diamonds

Bridge PET

LCS

Projected capacitance touchscreen stack-ups

PROJECTED CAPACITANCE TOUCHSCREENS In contrast, projected capacitance technology does not have the shortcomings of resistive touchscreens; this has enabled it to dislodge resistive touchscreens in many high-end and high-volume applications. Projected capacitance touchscreens are high performance in accuracy, power consumption, and refresh rate. They also feature excellent optical transmissivity (> 90%), meaning brighter and clearer displays. Furthermore, projected capacitance supports multi-finger touch input and gestures, thereby allowing significant improvements to the user interface. Popular gestures such as two-finger pinch and zoom let users zoom in or out on an image. Additionally, multi-touch lets OEMs develop custom gestures, which add value for the end user and can be promoted as product differentiators. Unlike resistive touchscreens, projected capacitance is durable, scratchresistant, free of aging symptoms, and needs no calibration. Projected capacitance does not use pressure for touch detection and can detect even the lightest of touches. Rather, projected capacitance reads finger touches based on the differential change in capacitance when a finger is placed on the

touchscreen. Without pressure-based sensing, this means that a bendable protective cover is no longer required. Thicker plastic or a glass cover lens that is strong and scratch resistant can be deployed for projected capacitance touchscreens. Contrary to resistive touchscreens, projected capacitance touchscreens can use glass or PET substrates and can be single or duallayered. Figure 2 shows several stack-up options for projected capacitance touchscreens. Note that a single-layer sensor with ITO deposited on a glass substrate will greatly enhance the optical clarity of the touchscreen. Because of the attractive properties of projected capacitance touchscreens, an increasing number of consumers are demanding devices that use this technology. In order to support high-end devices as well as medium and lower-end devices, touch panel and touch controller suppliers must be innovative in cutting cost while still supporting full feature sets. Projected capacitance touchscreen costs can be reduced by a number of design choices. Some high-impact choices are to use PET over glass substrates, polymethyl methacrylate (PMMA) instead of glass for the cover lens material, and fewer layers for the sensor stack-up. The single-layer low-cost sensor (LCS) by Cypress is an example of a projected capacitance solution that is cost competitive with resistive touchscreens. Such single-layer touchscreen

ITO

TECH ARTICLE 1 Layer COVER LENS

ITO

SLIM®

solutions have enticed cost-sensitive OEMs in making the switch from resistive touchscreens to projected capacitance. Currently, projected capacitance is taking over from resistive touchscreens as the solution of choice in the consumer electronics market. Touchscreen controller suppliers like Cypress have also made significant advances in technology to now support passive stylus and glove with projected capacitance. Several years ago, such non-finger input support could only be provided by resistive touchscreens. Looking forward, further innovation in projected capacitance for novel features such as hover—detection of a finger hovering some distance above the touchscreen—opens up possibilities to even more revolutionary and enriching user experiences.

“Projected capacitance does not use pressure for touch detection and can detect even the lightest of touches. Rather, projected capacitance reads finger touches based on the differential change in capacitance when a finger is placed on the touchscreen.”

SENSOR TECHNOLOGY

Chitiz Mathema is a product manager in the User Interface Business Unit at Cypress Semiconductor Corp., where he is responsible for product marketing of the TrueTouch touchscreen solution and CapSense touch-sensing solution. He has five years of experience in design, project management and product marketing. He holds a bachelors degree in ECE from the National Institute of Technology, Warangal, in India and an MSEE from Mississippi State University.

Resistive touchscreens continue to be the chosen solution in select cost-sensitive applications that require large touchscreens. They are also still prevalent in point-of-sale terminals, industrial, automotive, and medical applications. However, projected capacitance is now the dominant touchscreen technology in the market. Projected capacitance technology has replaced resistive touchscreens in high volume consumer electronics applications such as mobile phones, tablets, GPS, digital still cameras, and MP3 players by innovating to reduce solution costs as well as enhance features to make for more intuitive yet novel and exciting user interface options.

Christiana Wu is a Product Marketing Engineer for TrueTouch touchscreen solutions at Cypress Semiconductor Corp. She holds dual BS Degrees in Electrical Engineering and HumanCentered Design & Engineering from the University of Washington. She can be contacted at christiana.wu@cypress.com.

TECH ARTICLE

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SENSOR TECHNOLOGY

SENSOR FUSION INNOVATIONS FROM KIONIX

Navigate Emerging Markets Interview with Nader Sadrzadeh CEO of Kionix

COVER INTERVIEW

Kionix CEO: Nader Sadrzadeh Sensing a new future.

SENSOR TECHNOLOGY

Could you give us an overview of your MEMS inertial sensors? Kionix has traditionally been a developer and manufacturer of 3-axis accelerometers. Our high-performance, low power accelerometers were an early adoption in the consumer market. It was in fact the high rate of demand for accelerometers in the consumer market that helped fuel our companyâ&#x20AC;&#x2122;s growth. Then as the sensor content in consumer electronics and other focused markets became more diversified, Kionix expanded its product portfolio to offer new sensors and integrated solutions. We strive as a company, not only to develop and continually improve what we consider to be the best discrete accelerometers, but we are continuously trying to offer our customers

innovative solutions. While our customers have taken a discrete accelerometer, a magnetometer, and a gyro and used these three devices together to create sensor fusion, Kionix developed the KMX61G that replaces all three discrete products with an integrated solution that yields 9-axis equivalent output at lower cost and less power consumption. Beyond this, we have the soonto-be released next generation, the KMX62, which will integrate our own higher performance magnetometer, at even a lower cost. Our KX23H is another example of trying to give our customers more options. This product was developed in collaboration our sister company, LAPIS Semiconductor, and integrates the LAPIS low-power MCU into a single package with our accelerometer. This allows us to embed fusion code and applications without relying on an

COVER INTERVIEW application processor. By embedding our own set of pre-defined algorithms, we’re offering an outof-the box solution and trying to offload some of the pressure from the customer to develop software.

What industry do you see most relevant for growth for your sensor fusion products? Kionix has conventionally been a consumerfocused company with applications consisting of mobile, smartphones, gaming, tablets and free-fall detection for laptop computers. In terms of our integrated solutions, the consumer market and more recently, wearable devices, with applications such as health and fitness, will continue to be the most significant driver of growth.

Over the past few years, we have also started to focus on the automotive and industrial markets with applications such as navigation systems and tilt and spin control for washing machines, to name a few. Not only does this allow us to expand as a company, but it also gives us diversification and added stability to offset the ups and downs and volatility of the consumer market.

In what ways are the automotive and industrial products different from the consumer side? We look at them as completely different products, especially when you consider automotive. There are many factors to consider when it comes to the product design and packaging. We really had to start from the ground up—we have our core sensor technology,

“We strive as a company, not only to develop and continually improve what we consider to be the best discrete accelerometers, but we are continuously trying to offer our customers innovative solutions.”

SENSOR TECHNOLOGY

but we had to look at everything as a whole to produce what we define as an automotivegrade product. But beyond the product differentiation, it’s a completely different business mindset and strategy. Where-as the consumer market is typically driven by relatively short product life cycles and rapid product progression, the automotive and industrial markets constitute considerably longer development and product life cycles, are capital intensive and require long-term commitment. Together with our parent company, ROHM, Kionix is committed to drive our core sensing technology to deliver products and support our customers in the industrial and automotive markets. Our focus to-date has been on nonsafety applications, and whether we expand to safety applications is yet to be seen.

What is plasma micromachining? Plasma micromachining is a name that Kionix gave to its sensor process to differentiate it from other technologies being used in the marketplace. Over the last ten years, we have significantly evolved this technology, but it still forms the basis of how we manufacture our accelerometer elements today. It’s a unique technology that allows us to create a unique set of design IP and to tune our design to our manufacturing processes. Similar to other MEMS technologies, it’s a cost effective process that allows us to efficiently produce mass volumes. More recently, we’ve been diversifying our MEMS process base using ROHM’s larger

facilities and technologies. We have also transferred the plasma micromachining process to ROHM, and support dual manufacturing capabilities from both Ithaca, NY and Japan, and certainly intend to keep this process updated and active.

How has the ROHM acquisition affected Kionix? ROHM acquired Kionix nearly 5 years ago, and in-line with the company’s general practice of acquisitions, has supported Kionix to operate as an independent entity. But not to say there is any lack of support from our parent company. Stemming on ROHM’s core capabilities and scale, Kionix has been able to leverage necessary manufacturing and engineering resources, which have contributed to the companies continued growth. Since I joined Kionix last year, I’ve been driving to bridge the two companies closer together, leveraging the best of what ROHM and its subsidiaries have to offer to augment Kionix engineering, manufacturing and operations. All the while, maintaining the core of what Kionix was founded upon—a ‘start-up’ based on an engineering culture with aim to build the very best MEMS solutions with focus on performance and quality. And although the Kionix is part of a large global corporation today, we still operate on these same start-up principles. We will always continue to drive change, develop and innovate, improve our operations and processes, but this culture’s core foundation is something we don’t intend on changing.

COVER INTERVIEW “Together with our parent company, ROHM, Kionix is committed to drive our core sensing technology to deliver products and support our customers in the industrial and automotive markets.”

Kionix is known for its tag line: Sensing the Future. How do you sense the future of Kionix and the future of MEMS in general? The future is bright as the smartphone revolution gives way to other transformative technology trends such as wearables and the Internet of Things. These trends are about embedding intelligence and awareness in objects all around us. Sensing is core to this. So Kionix, and MEMS in general, are well situated to play a central role in these innovations. That’s not to say it will be easy. In fact, it will be a challenge for some manufacturers as the one-size-fits-all model for smartphones won’t suffice in a world where the products are much more diverse and the requirements and constraints are much more varied. Companies will need to learn to be adaptable and have flexible solutions to support a larger number of smaller volume customers. But Kionix has always prided itself in listening and attending to the customers’ needs. This has served us well and will work to our advantage as customers new to sensing will increasingly rely on sensor vendors to work closely, and in some cases, partner with them to deliver their innovative solutions. Couple that with our unique technologies, our strong engineering team and the support of our ROHM parent organization, and we’re very excited about the future.

SENSOR TECHNOLOGY

TECH ARTICLE

SMART SENSING

with Connectivity Solutions By Salvatore Bonina, Fabio Beffumo, System Lab - ST CENTRAL LABS, Industrial and Power Group (IPG) STMicroelectronics, Catania, Italy

he first generation of smart sensors was initially adopted for consumer use of gaming consoles and for the first smartphones. Now, smart sensing is pervasive in electronics applications for navigation, industry, building automation, health care, and medicine. Smart-sensor products represent the interface between the real “analog” world and digital electronics applications. To meet the market’s demands, STMicroelectronics offers a broad portfolio of products for developing a complete smart-sensing system.

SENSOR TECHNOLOGY

Electronics products in all application are becoming more intelligent. This is possible thanks to the introduction of embedded smart sensing, digital management, and connectivity features in electronics systems. Sensors and motion microelectromechanical systems (MEMS) in particular are among the most promising sectors of market growth in semiconductors in the coming years. TYPICAL SMART-SENSING PLATFORM The smart-sensing platform in figure 1 represents a complete solution for advanced smart-sensing applications. This diagram shows five main blocks: • Motion MEMS: accelerometer, gyroscope, magnetometer (LIS3MDL), digital compasses and iNEMO 6-axis or 9-axis inertial module (LSM6DS0, LSM9DS0) • Environmental Sensors: pressure temperature & humidity sensors • System & Data Management: low-power 8-bit (STM8L) or 32-bit (STM32L0, STM32L1) microcontrollers units (MCU) • Connectivity: Wi-Fi, Bluetooth low energy (BLE), sub 1 GHz, Ethernet • User Interfaces: Touch screen, proximity, touch key This platform analysis shows that the motion MEMS block offers a 9-degrees-of-freedom motion-sensing stage composed of a 3-axis digital gyroscope (L3GD20H) which measures the angular rate with a maximum scale of ±2000°/s, a system-in-package digital compass (LSM303C) module which features a 3-axis digital linear acceleration sensor able to sense the linear acceleration up to ±8g, and a 3-axis magnetometer with a magnetic range of 16 Gauss. ST’s portfolio also includes the 3-axis digital

Figure 1: Typical block diagram of a smart-sensing platform.

or analog accelerometers (LIS2DH12, LIS3DSH, H3LIS331DL, LIS344ALH) in a single package with up to ±400g of measurement range. Inside the environmental block, MEMS pressure sensors represent the 10th degree of freedomin-motion recognition. In fact, with an absolute range of 260 to 1260 mbar and a resolution of 0.020 mbar, and the LPS25H is able to measure altitude and determine floor position in indoor navigation. Pressure combined with analog or digital temperature sensors (STTS751, STLM20) and humidity sensors (HTS221) are key elements for ambient monitoring. The connectivity block offers four alternative solutions: • A Bluetooth low-energy (BLE) controller (BlueNRG), plus frequency work at 2.45 GHz and transmission rates of ~200 kilobits • Wi-Fi module (SPWF01SA or SPWF01SC) compliant to the IEEE 802.11 b/g/n standard at frequency of 2.4 GHz with embedded STM32 ARM Cortex-M3, 1.5 MB or 512 kB of Flash Memory and 64 kB of RAM memory • Very low-power RF transceiver for the sub 1 GHz band product (SPIRIT1) designed for work

TECH ARTICLE

at different frequency bands supporting 2-FSK, GFSK, OOK, ASK, and MSK • ST’s product (STE100P) for fast Ethernet, a 10/100 Mbps transceiver compliant with IEEE802.3u 100Base-TX and IEEE802.3 10Base-T For the digital management of this platform, it is possible to choose an 8-bit or 32-bit low-power microcontroller (MCU). Low-power features of MCUs, as well as for the overall system components, are a fundamental characteristic for portable consumer devices and also for 24-hour-monitoring systems with available back-up batteries in case of grid blackout. Touch-sensing products (touch screen, touch key, proximity) and user interface represent an intuitive input and output instrument able to simplify setting changes in many applications, including in-home displays.

INTEGRATED, EFFICIENT, INTELLIGENT The products and solutions featured in this article show that for an integrated, efficient, and intelligent solution, the system architecture needs to embed three key features: smart sensing, digital management with realtime control, and advanced connectivity solutions. With a dedicated portfolio and deep systems know-how, STMicroelectronics is the key supplier for a wide spectrum of smart electronics applications.

“Sensors and motion MEMS in particular are among the most promising sectors of market growth in semiconductors in the coming years.”

SENSOR TECHNOLOGY

PRODUCT HIGHLIGHT

Product Overview of the

Smart-Sensor Hub from Kionix

The KX23H smart sensor hub from Kionix integrates a 16-bit accelerometer and ARM Cortex-MO in a tiny LGA package to simplify sensor integration and enable more efficient designs. Because the Cortex-M0 is a full multipoint control unit (MCU), certain applications will be able to run wholly within the KX23H, making it not just a sensor hub but the main application processor. Kionix also includes a library of advanced motion processing software.

SENSOR TECHNOLOGY

Key Features KX23H MCU Features: • ARM Cortex™-M0 32MHz • 128 kB Flash ROM • 16 kB SRAM • Power consumption (MCU only): 2.5μA (sleep); 1.5mA @ 32kHz; 6mA @ 32MHz • I2C master port • I2C slave port • 3 GPIO Interrupt capability

KX23H Accelerometer Features: • Low power : 1μA@ standby; 2μA@3.1Hz; 146μA@1.6KHz • ±2g, 4g, 8g full scale • Data Rate 0.781Hz to 1.6KHz • 16-bit resolution • Low noise with FlexSet Performance Optimizer • Embedded 256-byte FIFO/FILO buffer • Internal voltage regulator • Embedded wake-up function • Digital High-Pass Filter Outputs • Integrated Directional Tap/DoubleTap™ and device-orientation algorithms • Excellent Temperature Performance • High Shock Survivability (10,000g)

PRODUCT HIGHLIGHT

Tech Specifications

The accelerometer is based on Kionix’s highest performance design and features a selectable ±2, 4, or 8g full-scale range, embedded 256-byte first-in-first-out (FIFO) or first-in-lastout (FILO) buffer, and utilizes Kionix’s FlexSet Performance Optimizer to ensure low-noise operation. It includes an embedded wake-up function, as well as algorithms to detect device orientation and Directional Tap/Double-Tap™. The Cortex-M0 in the KX23H is a full-featured, lowpower microcontroller from LAPIS, one of Kionix’s sister companies within the ROHM group. The Cortex-M0 uses an I2C slave interface to communicate with the host, and an I2C master interface to communicate with the integrated accelerometer as well as external sensors. 128KB of flash and 16KB of SRAM allow sensor fusion and data analysis algorithms to be run directly in the KX23H. The final data is then buffered until the main application processor requests it. This allows the sensor subsystem to be developed and work independently of the application processor, simplifying system design and verification while improving reliability.

To watch a video overview of the KX23H smart sensor hub from Kionix, click the image below

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SENSOR TECHNOLOGY

MagGyro from Kionix

Balances Performance

with Cost

By: John Chong, Vice President of Product and Business Development, Kionix

PRODUCT HIGHLIGHT

his is definitely the age of the â&#x20AC;&#x153;quantified selfâ&#x20AC;? in which people have a growing thirst to quantify and track everything about their lives. Combine this with the burgeoning Internet of Things (IoT), which strives to embed intelligence in common, everyday devices and share the information virtually everywhere, and it is evident that society is entering a new age of technology driven by the availability of inexpensive and ubiquitous computing and connectivity. At the heart of this trend is data about individuals and their surrounding world. The source of this data is sensors, and so the logical extension is a trend towards ubiquitous sensing.

SENSOR TECHNOLOGY

This is definitely the age of the “quantified self” in which people have a growing thirst to quantify and track everything about their lives. Combine this with the burgeoning Internet of Things (IoT), which strives to embed intelligence in common, everyday devices and share the information virtually everywhere, and it is evident that society is entering a new age of technology driven by the availability of inexpensive and ubiquitous computing and connectivity. At the heart of this trend is data about individuals and their surrounding world. The source of this data is sensors, and so the logical extension is a trend towards ubiquitous sensing. Sensors are following computing in that technology advances are allowing sensors to become smaller and more mobile. In addition to the smartphone, newer quantified self- devices are taking the form of health and fitness monitors, headsets and helmets, wearable electronics, and sports equipment. Multiple market analysts have predicted a significant increase in the monitoring device and applications market. These devices enable the user to measure dozens of parameters that include movement, motion and form, pedometry, cadence, swings, and gesture recognition. IHS Electronics & Media has forecasted that the performance-monitoring market will reach $2.3 billion in 2017 and that, cumulatively, over 250 million of these devices will ship between 2012 and 2017. Innovative microelectromechanical systems (MEMS) inertial-sensor industry suppliers have stepped up to meet growing consumer demand for these devices. To support increasingly

“Sensor fusion software intelligently combines data from the individual sensors for the purpose of improving application or system performance.”

intelligent and improved capabilities, a trio of devices has been combined via intelligent sensor fusion algorithms to provide the foundation for motion and orientation awareness. These devices—a 3-axis accelerometer, 3-axis magnetometer, and 3-axis gyroscope—are united as a 9-axis inertial measurement unit (IMU) that provides functions and features such as screen orientation detection, gesture recognition, interactive gaming, step counting, personal navigation, and free fall detection. But, inclusion of all three sensors in a new device design presents challenges in terms of increased power consumption, board space, and costs. A new category of 6-axis sensors that deliver 9-axis capabilities are emerging as a valuable and enabling design option for consumer electronics market original equipment manufacturers (OEMs). These combination products provide significant benefits to consumer-electronics manufacturers by reducing overall board space, cost and power consumption, thus enabling manufacturers to include motion sensors in a greater number and variety of products.

PRODUCT HIGHLIGHT

Traditional gyros provide excellent performance and important functionality, however, it is the largest, most expensive and the most power hungry of the three sensor types. This has limited a gyroâ&#x20AC;&#x2122;s usage in many mobile products. Now, 6-axis sensors combined with smart- fusion software have given product designers a low power, reduced cost, and size alternative to traditional gyros, which opens up new possibilities for the inclusion of gyro-based functionality in their products. This article will present the advantages of integrating 6-axis solutions that deliver the equivalent of 9-axis output while cutting power consumption by as much as 90 percent. It will also illustrate that this solution, using what has been termed as a magnetic gyro (or MagGyro for short), is not only a good alternative to traditional gyros, but can be used to augment and calibrate traditional gyros.

Basics of 9-Axis Sensor Fusion and the Magnetic Gyro To accurately represent motion and orientation, three different sensors are typically employed: an accelerometer, a magnetometer, and a gyroscope. An accelerometer measures linear acceleration and orientation relative to gravity, while a magnetometer is used to sense the earthâ&#x20AC;&#x2122;s magnetic field and orient oneself relative to the magnetic north. Rounding out the sensors needed for motion and orientation are gyroscopes that measure rotational speed to detect changes in pitch, roll, and yaw.

Accelerometer + Magnometer + Gyroscope

Micro-Amp Magnetic Gyro

Accelerometer + Magnometer

Accelerometer

Figure 1: Fusing sensor data from a traditional 9-axis, 3-sensor solution enables a substantial increase in performance over the individual sensors as each sensor compensates for what the other sensors lack. However, inclusion of the traditional gyroscope causes the largest increase in cost, size, and power consumption. The MagGyro provides an option that balances performance with a substantial decrease in cost, size, and power consumption.

SENSOR TECHNOLOGY 9-Axis Sensor Fusion Motion and Orientation Accelerometer

• Measures linear acceleration • Orientation relative to gravity

+Y UP

-X WEST

-Z NORTH

Magnometer

• Used as e-compass to orient relative to earth

Gyroscope

• Used to measure rotational speed

Figure 2: Data from accelerometers, magnetometers, and gyroscopes are combined to measure motion and detect orientation.

Sensor fusion software intelligently combines data from the individual sensors for the purpose of improving application or system performance. A good illustration of sensor fusion is the MagGyro itself— the 6-axis sensor that in addition to giving acceleration and magnetic field information, can output angular velocity measurements. Since gravity is a form of acceleration, an accelerometer can be used to detect orientation relative to gravity (up and down). A magnetometer coupled with an accelerometer can form an e-compass to determine orientation relative to magnetic north (north, south, east, and west). Together, this provides a device’s orientation in 3D space. Since angular velocity is just a change in orientation, sensor fusion software can monitor orientation and calculate angular velocity, hence emulating what a physical gyro does. This would not be possible off the earth, but for applications on the earth, this can give the equivalent 9-axis output that a traditional 3-sensor solution provides. A 9-axis solution using a MagGyro is an excellent addition to the system designer’s toolbox because of what it enables the designer to

+Z SOUTH

+X EAST -Y DOWN

accomplish. The concept is not new, but achieving a solution with the level of performance required in today’s applications has been challenging for many sensor vendors. That’s because the performance of this solution is highly dependent on the quality of its components— the accelerometer, the magnetometer, and the sensor fusion software must all be optimized to create an effective magnetic gyro. The most important properties of the accelerometer and magnetometer are their noise and stability. Since the sensor fusion software uses these as the basis for calculations of angular velocity, any errors in acceleration and magnetic field will affect angular velocity accuracy. In addition, the latency of the measurements and the synchronization of the readings from the accelerometer and magnetometer are important. Any time delta between readings can show up as errors in the gyro output and is a key reason to pair the accelerometer and magnetometer as a combination product. Special consideration, too, must be given to the software, since it performs many functions

PRODUCT HIGHLIGHT that make the MagGyro viable. Intelligent filtering of noise, identifying and mitigating magnetic anomalies, and trading off accuracy versus responsiveness are all aspects of the implementation that are crucial to the performance and the end user’s experience. In addition, the software needs to be efficient both in terms of code size and processor usage in order to not squander the benefits provided by the MagGyro. The number one reason a physical gyro is not used in many applications is power consumption. Depending upon the specific comparison, 9-axis solutions with a MagGyro reduce power consumption by a factor of five to ten. For example, Kionix’s MagGyro runs at 950µA (450µA sensor + 500µA software) compared to a standalone physical gyro running at 5000µA, offering a 5x reduction in power. Furthermore,

since most systems with a physical gyro already include an accelerometer and magnetometer, comparing the power consumption of a 9-axis solution using a physical gyro to that of one using a MagGyro entails comparing the current consumption of the physical gyro to the power consumed by the MagGyro software (500µA) yielding a significant 10x reduction.

Algorithm & Sensor Requirements ACCELEROMETER

Low Noise (150–200μg/√Hz)

MAGNOMETER

Low Noise (0.2μT RMS) Response / Latency < 1ms

SOFTWARE

Intelligent Sensor Fusion • Calibration, Magnetic Anomaly Rejection • Filtering and Management of Noise and Non-Ideal Time Varying Conditions • Proper tradeoff between accuracy and responsiveness • Optimization of code for minimal Memory and MIPS requirements

Figure 3: The Kionix Magnetic Gyro solution offers considerable size savings, enabling OEMs to have full 9-axis outputs in a 3x3x0.9 mm package, which constitutes a 45 percent reduction compared to other options. Kionix’s KMX61G delivers the world’s first highly accurate gyro emulation using as little as one-tenth the power of a traditional 9-axis solution. This, combined with the KMX61G’s high-performance hardware and innovative software, gives mobile product developers the dramatic power savings that enables a new and wider range of application possibilities.

SENSOR TECHNOLOGY

When is a MagGyro Solution the Right Solution? The answer is that it depends on the requirements and needs of the application, as well as the constraints. There are so many new applications that can benefit from gyroscopic information as sensing capabilities move into the objects we carry, use, and wear. Consider the motion of our joints, from head twists to wrist rotations to knee extensions—so many human motions are rotational in nature. But as smartphones grow larger, the opposite trend is occurring for the newer devices since objects that are worn or carried need to be small, light, and wireless. It is true that the MagGyro is not as accurate as a physical gyro, but it does provide accuracy that is good enough for many designs while also bringing significant benefits. In truth, the question for the system designer will often not come down to whether to use a MagGyro, but whether to include a physical gyro. Implementing a MagGyro is always beneficial. In many designs it can be used to replace the physical gyro relieving some of the cost, size, and power burden that comes with a physical gyro. In other cases, pairing the MagGyro with a physical gyro offers distinct advantages. Since applications using a physical gyro also include an accelerometer and magnetometer, inclusion of the MagGyro with the physical gyro comes with little additional cost. It can provide the gyro outputs in situations when the physical gyro is turned off to conserve power, thereby intelligently balancing performance and power consumption. Also, it can be employed in situations where the accuracy of the physical

“The MagGyro is used to augment and enhance the physical gyro by calibrating the physical gyro’s bias and sensitivity.”

gyro is required. The MagGyro is used to augment and enhance the physical gyro by calibrating the physical gyro’s bias and sensitivity. The market penetration of IMUs continues to increase because of their ability to address the needs of product designers who must support the growing demand to make devices smarter. The flexibility offered by 9-axis solutions with a magnetic gyro provides an important addition to the system designer’s toolbox and opens up new application opportunities that ultimately lead to positive market growth.

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