Internet of Things Handbook April 2018

Energy efficient route to managing low-voltage energy harvesters Page 6

The checklist: 5 IoT lessons to make your IoT design project a success Page 38

APRIL 2018

Internet of Things H A N DBOOK

00 FINAL COVER IoT HB 04-18.indd 1

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Trusted IoT Authentication to Google Cloud IoT Core ATECC608A: Your Secured Hardware Root of Trust

Combined with the Google Cloud IoT Core service, the ATECC608A CryptoAuthentication™ device provides secure and trusted storage for the root of trust. The IoT hardware private key used for the authentication to Google Cloud Platform is protected in the ATECC608A against side channel attacks and physical tampering. In addition, the ATECC608A offers secure storage for firmware updates and secure boot credentials, enhancing current IoT hardware designs.

Leverage 20 years of in-manufacturing security expertise by choosing Microchip.

Provisioning happens at Microchip’s secure facilities using Hardware Secure Module (HSM) networks in the ATECC608A. During production, the ATECC608A will generate the private keys inside the device within Microchip factories, avoiding any exposure in the IoT device life cycle.

ATECC608a security development kit for Google Cloud IoT Core

www.microchip.com/ATECC608aGCPiotCore The Microchip name and logo, the Microchip logo are registered trademarks and CryptoAuthentication is a trademark of Microchip Technology Incorporated in the U.S.A. and other countries. All other trademarks are the property of their registered owners. © 2018 Microchip Technology Inc. All rights reserved. 3/18 DS00002677A

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INTERNET OF THINGS HANDBOOK

Halt and catch fire:

The perils of cheap PoE

Dave

Jeskey tells an interesting story about what happened when an LED lighting company operated a few of its products in a test chamber. The RJ45 plugs, used for making a connection to a Power over Ethernet cable, melted.

The RJ45 plugs came from Sentinel Connector Systems where Jeskey is director of sales and marketing. When Sentinel tore down and examined the damaged units, the problem became obvious: Cheaply built RJ45 jacks into which Sentinel’s plugs fit.

“There were transformers built into the jacks that had been badly hand-wound rather than machinewound. They had also substituted a cheaper ferrite core that was slightly conductive,” says Jeskey. The melting of the RJ45 plug (which had been designed to melt at 250⁰C, more than melting point of tin) had probably prevented the poorly made jack from causing a fire, he says. It let the conductors pull away and disconnect before the heat from bad connections caused more damage.

The near catastrophic failure of that RJ45 jack is a microcosm of the problems that will soon plague PoE installations. New specifications let PoE lines deliver up to 100 W using plugs, jacks and cabling that are similar to those for ordinary Ethernet. But small imperfections and corner-cutting on costs can make for big problems when that much power passes through the relatively small conductors of Ethernet connections.

Corner-cutting on PoE gear is particularly widespread among foreign suppliers Jeskey adds. One of the easiest places to cut corners is with gold plating.

“The plating on a contact is supposed to be 50 µin. of 24-carrot gold over a minimum of 50 µin. of pure nickel. We’ve studied over 70,000 part numbers and 94% of them failed to meet those minimum standards. I’ve seen parts using as little as 1.5 µin. of gold and even parts with a statement in the specification saying, ‘gold color only.’”

It isn’t just scrimping on gold that is problematic. “RJ45 conductors have a surface smoothness specification. The proper way to realize it is to first electropolish the contacts, coat them with nickel, and then add the gold. Some foreign suppliers will just wire-brush the surface to make it smooth. The brushing creates ridges and valleys which make the connection less reliable,” says Jeskey.

Other problems arise because PoE connections are hot pluggable. Small sparks form when the plug disconnects from the jack.

The sparks may cause problems even in well designed connections, he says. Cheap connections are even worse. “Jack contacts are supposed to be phosphor-bronze but some suppliers cheat with brass and other cheaper metals,” he adds. “When you create a spark, it alters the crystalline structure of the contact and eventually makes it brittle. Some equipment makers claim that spark isn’t a problem because it happens away from the data transmission lines. But a spark alters the whole contact, not just the area where it occurs.”

And it isn’t just PoE connections that are problematic. Ethernet cables can contain different wire sizes. “Some companies use 22 gauge wire, which is good if you have plugs and jacks able to handle it,” Jeskey says.

“The best-selling cable contains 28-gauge wire. But some foreign suppliers are selling Ethernet cable with much thinner 30 and 32-gauge wire. That is dangerous.”

LEE TESCHLER | EXECUTIVE EDITOR

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INSIDE EEWORLDONLINE.COM

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21

25

02 HALT AND CATCH FIRE: THE PERILS OF CHEAP PoE

34 30 BLUETOOTH LOW ENERGY PROCESSORS

06 ENERGY EFFICIENT ROUTE TO MANAGING

LOW-VOLTAGE ENERGY HARVESTERS

It can be tough to harvest energy from innovative IoT devices such as thermoelectric generators built into clothing. A new kind of MOSFET is designed to work with the super-low voltages involved.

ADCs with SDR allow designers to reduce design efforts and focus on implementing more fashionable features.

15 BULK ACOUSTIC WAVE FILTERS MAKE LIFE

EASIER FOR WI-FI FRONT-END DESIGNERS

BAW filters help overcome the biggest challenges facing Wi-Fi front-end designs, including thermal management, interference, and RF linearity.

21 MORE ACCURATE CHECK-UPS

FOR BATTERY HEALTH

REAL-TIME DATA = PRODUCTIVITY

NEEDS INDUSTRIAL BATTERIES

Advanced lithium battery technology delivers long-life power and high pulses to expand remote wireless connectivity throughout the Industrial Internet of Things.

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STAFF & CONTENTS PAGE IoT HB 4-18 V1.indd 5

Which parts of your machines are critical to maintaining uptime and increasing productivity? How do you identify them? With data from IoT-based sensors, you’ll have your answers.

38 THE CHECKLIST: 5 IoT LESSONS TO MAKE YOUR

IoT DESIGN PROJECT A SUCCESS

With IoT designs, decisions made on Day 1 can lead to success or failure. These best IoT design practices can help you avoid common missteps, which will increase the chances of success.

40 HOW THE IoT CAN SUPPORT CLEAN OPERATION

A new technique may eliminate the guesswork involved in figuring out how much life batteries have left.

25 WHY THE INDUSTRIAL IoT

FOSTER INNOVATIONS IN HEALTHCARE

Applications for fitness tracking and remote health monitoring have grown to such an extent that chip makers have developed SoCs optimized for counting heart beats and calculating glucose levels.

34 SMART TECHNOLOGY AND

10 SOFTWARE-DEFINED RADIO POWERS THE IoT

APRIL 2018

IN MOBILE OFF-HIGHWAY APPLICATIONS

With a common, efficient language, a CAN bus standard moves the discussion of how actuator communications will be managed to what exactly the user wants to accomplish. This type of an IoT application increases design flexibility for mobile off-highway equipment.

45 INDUSTRIAL IoT IS DISRUPTING SUPPLY CHAINS

Within the next few years, nearly every industrial company should be implement IoT projects or risk being disrupted by those that already have.

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Energy efficient route to managing low-voltage energy harvesters It can be tough to harvest energy from innovative IoT devices such as thermoelectric generators built into clothing. A new kind of MOSFET is designed to work with the super-low voltages involved.

ROBERT CHAO | ADVANCED LINEAR DEVICES INC.

Energy

harvesting devices make headlines because they are thought to be important for internet-ofthings applications. As an example, consider a flexible fabric capable of generating power from body heat. According to researchers in China and Australia who recently described the new material in the journal Scientific Reports, it can generate 4.3 mV into a large impedance when exposed to a temperature difference of 75.2°K. However, the hype surrounding such developments rarely mention the problems involved in working with such low voltages and the miniscule amount of energy being harvested. The difficulty with energy harvesters such as the fabric mentioned above is that the voltages generated are close to the gate-threshold voltage of ordinary transistors. It can be tricky to manipulate harvested energy when it exists at such low voltages.

Consequently, there has been a need for semiconductor devices able to function with low levels of input energy. One development in that category is a zero-gate threshold voltage P-Channel MOSFET array. Called the ALD310700A/ALD310700, it is intended for use in small-signal precision applications involving zero threshold voltage.

The array targets designs requiring operating voltages below a half volt. Notable device features include a minimum operating voltage of less than 0.2 V, minimum operating current of less than 1 nA, and matched and tracked temperature qualities.

Zero-threshold MOSFETs are a special case of a family of MOSFETs called EPAD (Electrically Programmable Analog Device) where the individual threshold voltage of each MOSFET is fixed at zero. Here, use of EPAD technology leads to low-voltage switching with sharp turn-off and low leakage qualities resembling those of conventional MOSFETs. In these zero-threshold transistor arrays, the zero-threshold voltage is defined as Ids = 1 µA at Vds = 0.1 V when the gate

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A L D 3 1 0 70 0

The ALD310700A/ALD310700 high-precision P-Channel MOSFET arrays are available in a quad version with a block diagram as depicted here.

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ENERGY EFFICIENT ROUTE

Fo r w a r d Tr a ns f e r C h a r ac t e r i s t i c s Ex p ande d ( su bth res ho ld ) A view of the forward transfer curves for the ALD310700A/ALD310700 shoes how the devices can help in the creation of circuit designs with low operating voltages, as when operating from power supplies of less than +0.5 V, where the circuits operate below the threshold voltage.

This feature also enhances input/output signal operating ranges, especially in environments characterized by low operating voltages.

voltage Vgs = 0.0 V. Technically, the zero-threshold devices are enhancement-mode transistors when operated above threshold voltage and current level (greater than 0.0 V and 1 µA). However, these devices can also be used as normallyon MOSFETs because they conduct a current and behave like a fixed-resistor even when the gate voltage is at 0.0 V. A modulating signal voltage at the gate can adjust the drain current, even to negative-gate voltage levels, down to a subthreshold voltage level of about -0.4 V, at which point the transistor is completely off.

A zero-threshold MOSFET reduces or eliminates inputto-output voltage level shift in circuits where the signal is referenced to ground or V+. This feature can significantly reduce output signal level shift from that of the input and enhances operating signal range, especially for low operating voltage environments. With zero-threshold devices, an analog circuit with multiple stages can be constructed to operate at extremely low power supply or bias voltage levels.

The EPAD technology upon which the zero-threshold MOSFET is based employs a CMOS MOSFET whose threshold voltage and on-resistance characteristics can be electrically programmed to a precise level. Once programmed, the set parameters are indefinitely stored within the device even after power is removed. This technology makes use of a floating gate structure which can be precision-trimmed to produce tightly controlled transistor electrical qualities.

In general, EPAD devices can serve as functional trimmer pot substitutes in conjunction with external fixed resistor(s). The primary function of an EPAD MOSFET is as a high-precision, high-stability MOSFET that displays a special family of voltageversus-current curves. Originally, EPAD MOSFETs were used

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as trimmers where the on-resistance of the MOSFET could be precisely set to replace a trimmer potentiometer. But many other uses have emerged. An EPAD MOSFET is actually a CMOS IC, and it has some general limitations of typical CMOS devices such as a maximum voltage rating of 10 V. It is sensitive to electrostatic discharge and has an NMOS MOSFET device output.

BASICS OF LOW-VOLTAGE OPERATION Low-voltage systems -- namely those operating at 5 V, 3.3 V or less -- typically require MOSFETs that have threshold voltage of 1 V or less. The threshold, or turn-on, voltage of the MOSFET is a voltage below which the MOSFET conduction channel rapidly turns off. For analog designs, this threshold voltage directly affects the operating signal voltage range and the operating bias current levels.

At or below threshold voltage, an EPAD MOSFET exhibits a turnoff characteristic in an operating region called the subthreshold region. This is when the EPAD MOSFET conduction channel rapidly turns off as a function of diminishing applied gate voltage. The conduction channel induced by the gate voltage on the gate electrode drops exponentially and causes the drain current to fall exponentially.

However, the conduction channel does not shut off abruptly with diminishing gate voltage. Rather, it decreases at a fixed rate of approximately 116 mV/decade of drain current reduction. Thus, if the threshold voltage is +0.20 V, for example, the drain current is 1 µA at VGS = +0.20 V. At VGS = +0.09 V, the drain current would drop to 0.1 µA. Extrapolating from this, the drain current is 0.01 µA (10 nA) at VGS = -0.03 V, 1 nA at VGS = -0.14 V, and so forth. This subthreshold characteristic extends

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Low v o lt a g e c u r r e n t s o u r c e m i r r o r

Low vo lt ag e c u r r e n t s o u r c e w i th g at e c o n t r o l

Low v o lt a g e d i f f e r e n t i a l a m p l i fi e r

The gate threshold voltage VGS(th) on the ALD310700A/ ALD310700 is set precisely at 0.00 ±0.02 V, featuring a typical offset voltage of only ±0.001 V (1 mV). As the MOSFETSs are on the same IC, they also exhibit excellent temperature tracking.

The operating current level varies exponentially with gate bias voltage at or below the gate threshold voltage (subthreshold region). The circuit can also be biased and operated in the subthreshold region with nanoamps of bias current and nanowatts of power dissipation. These qualities make the MOSFETs versatile design components for a broad range of precision analog applications such as basic building blocks in current mirrors and differential amplifiers.

all the way down to current levels below 1 nA and is limited by other currents such as that for junction leakage. At a drain current to be declared “zero current” by the user, the corresponding VGS voltage can be estimated. Note that using the above example, with VGS(th) = +0.20 V, the drain current still hovers around 20 nA when the gate is at zero volts, or ground.

When supply voltages drop, the power consumption of a given load resistor drops as the square of the supply voltage. So one of the benefits in reducing supply voltage is to reduce power consumption. However, a decreasing power supply voltage and power consumption go hand-in-hand with a diminishing useful ac bandwidth.

Simultaneously, noise has a bigger impact on low-level signals. So circuit designers must make the necessary tradeoffs and adjustments in any given circuit design and bias the circuit accordingly One other key benefit of using matched-pair EPAD MOSFETs is to maintain temperature tracking. In general, for EPAD MOSFET matched pair devices, one device of the matched pair has gate leakage currents, junction temperature effects, and drain current temperature coefficient as a function of bias voltage that cancel out similar effects of the other device. Temperature stability can be further enhanced by biasing the matched-pairs at the Zero Tempco (ZTC) point, though that could require special considerations for circuit configurations and power consumption.

REFERENCES Advanced Linear Devices Inc. www.aldinc.com

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Software-Defined Radio powers the IoT ADCs with SDR allow designers to reduce design efforts and focus on implementing more

RYAN LIU | MICROCHIP TECHNOLOGY INC.

fashionable features.

Software-defined

radio (SDR) technology finds its way into everything from multi-carrier multi-standby smartphones to innovative multi-mode mobile internet electronics. When enabled by SDR, a configurable transceiver works flexibly with software-defined carrier frequencies, easing the task of RF design.

For many years, the evolution of wireless communication standards depended on large-scale hardware upgrades.

Today, however, the adoption of SDR technologies makes it easier to find alternatives to expensive hardware.

The primary motivation of the SDR concept is to overcome added costs. The three essential methods used in SDR are to move the broadband analog-digital conversion (ADC) and digital-to-analog converter (DAC) as close as possible to RF devices, use hardware as the basis of wireless communication, and maximize software options to enable functions that are traditionally only available in the RF and intermediate frequency (IF) analog domain.

To make the system more flexible at a lower cost, items such as the operating frequency band and modulation method are configured by software in the digital domain. SDR lets the same hardware handle multiple frequency bands by loading the relevant software as required. This scheme works for products ranging from smartphones to sensor networks. Meanwhile, market forces are driving the steady development of high-speed, high-precision ADC technology to enable fast and accurate processing of wireless broadband signals. ADC limitations previously constituted one of the main bottlenecks to SDR. Receiver design is a critical priority for SDR. So it is useful to review the special requirements for SDR receiver implementation. The key is the front-end.

Implementation of the entire SDR system dictates how to partition specifications for the ADC and other key components. High speed, dynamic range, and richness in software configurations are essential in the ADC.

Ty p i c a l i d e a l S D R a r c h i t e c t u r e

An Ideal software-defined radio (SDR) receiver architecture is one in which there is no need for down conversion of incoming frequencies.

Practicalities of ADC technology make this architecture difficult to realize.

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Ty p i c a l d ow n - c o n ve r s i o n r ad i o a r c h i t e c t u r e

SDR receivers generally can be divided into three categories based on their signal bands: RF sampling receivers, IF sampling receivers, and baseband sampling receivers. RF sampling most resembles the ideal SDR structure: An ADC connected to an A typical block diagram of a digital radio antenna to form a receiver receiver employing an IF down conversion and a DAC connected to and quadrature demodulation. an antenna to form the transmitter. However, the two major performance bottlenecks — RF devices and ADCs — make the ideal structure the most difficult to realize at a reasonable cost.

Among structures in the other two categories, the most widely used are zero IF receivers, low IF receivers, and bandpass sub-sampling high IF receivers. As a quick review, a zero-IF receiver (also known as a direct conversion receiver) demodulates the radio signal using synchronous detection driven by a local oscillator (LO) whose frequency is identical to that of the carrier frequency of the signal being demodulated. In low IF receivers, the RF signal is mixed down to a non-zero low or moderate IF, usually in the range of a few megahertz to a few hundred kilohertz. In sub-sampling receivers, the RF signal is sampled using a frequency lower than twice the maximum input frequency but larger than twice the signal bandwidth. One of the low-frequency replicas resulting from the sampling process, which contains the baseband signal, is then directly digitized.

Co m p a r i s o n o f p o p u l a r S D R r e c i eve r SDR Implementation

Advantages

Zero IF Receivers

»» »» »»

No image rejection filters Baseband ADC/DSP devices Compact size, fewer discrete devices

Low IF Recievers

»» »» »»

Resolve DC offset and flicker noise Compact size, fewer discrete devices Medium cost

»» »» »»

Medium working frequency Out-of-band harmonics of signals Medium requirements on filters, relatively balanced component specification partitioning Low cost

Bandpass Sub-sampling High IF Recievers

»»

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»» »» »» »» »» »» »»

»» »» »» »»

When the ADC is placed after the mixer, the performance constraints are the lowest for ADC in zero IF receivers. Because LO frequency (fLO) and the RF signal central frequency into the mixer (fRF) are the same, the ADC need only process the signals in the baseband. Ideally, there are no image interferences. Therefore, an image rejection filter is unnecessary, eliminating the need for expensive surface acoustic wave (SAW) filters. However, the biggest challenge of zero IF is that either dc offset and orthogonal errors are unavoidable, or the calibration algorithm is overly complex, especially when implemented using discrete components.

The dc offset typically originates from a non-ideal mixer.

The mixer LO signal leaks and loops s t ruc tu res back into the receiver signal path (known as the LO leakage) through parasitics. It is also amplified by the Disadvantages transmitter antenna in that loop.

Because this interference changes LO leakage DC offset, flicker noise amplitude with the transmitter I/Q mismatch amplification – and the frequency In-band harmonics of signals is equal to fLO in the receiver – the time-variant dc offset is generated Medium requirements in image rejection at the mixer output. Adjacent Component Mismatch objects passing the antenna will In-band harmonics of signals further complicate the situation.

DC offset can lead to severe More discrete devices overloading; in other words, it can Relatively higher image form a strong blocker at the signal rejection needed center frequency.

Better bandwidth and jitter from ADC Orthogonal error is primarily Faster DSP caused by mismatched inherent errors between channels. The

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S O F T WA R E - D E S I G N E D R A D I O

situation is especially challenging in discrete structures, as it results in image interference and deteriorating constellation specifications like Inter Symbol Interference (ISI). In scenarios such as 64 quadrature amplitude modulation (QAM) for the LTE standard, the higher the modulation efficiency, the more the jitter can degrade the SNR. In low IF receivers, the ADC bandwidth must be twice that in zero IF architecture. Low IF receivers use an fLO which has a slightly lower-Q filter specification from fRF. This solves the dc offset problem and controls LO leakage.

While orthogonal error and mismatch are still issues with this structure, a low IF SDR with balanced block specifications is more economical and effective than zero IF designs.

The third widely used structure is bandpass sub-sampling high IF receivers, commonly known as high IF. The ADC must work at a higher frequency than in zero IF or low IF receivers. Modern ADC technology makes this design feasible at a reasonable cost.

One methodology for implementing a low IF or high IF receiver is to combine a superheterodyne front end with a highly digitized back end. It is vital to emphasize that this no longer sticks to the strategy of a fixed IF frequency as in a traditional superheterodyne structure.

Instead, it fully allows the software to tune the channel parameters and thereby overcome the superhet’s traditional disadvantage of being able to tune to only a narrow band of frequencies.

Both low IF and high IF receiver approaches need down-conversion and thus a mixer. Digital mixers often take the form of a numerically controlled oscillator (NCO). With an NCO the Inphase/Quadrature (I/Q) signal frequency can be accurate regardless of the LO frequency. These types of mixers can handle a broader band of frequencies than their analog counterparts. Signals will not have dc offset or obvious image interference, even when downconverted to dc. The combination of

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Ap p l i c at i o n v i ew

S y s t e m v i ew

Software-defined radio implemented with discrete components can be subject to degradation and interference sources that arise because the components are distributed about one or more printed circuit boards. These sources can be viewed in terms of both the application (top) level and system level (bottom).

Ap p l i c at i o n v i ew

Software-defined radio can be implemented using an IC to avoid many of the factors that can degrade performance when SDR components sit on PCBs.

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The MCP37DxxADC contains a digital down converter that helps simplify the design of the IF system necessary for receivers in software-defined radios.

digital mixers, oscillators, and decimation filters is generally referred to as a digital down-converter (DDC).

CHALLENGES ON THE CIRCUIT LEVEL The overall performance of an SDR made with discrete components can be compromised by the number of devices involved and PCB-level imperfections.

The discrete scheme requires careful thought about non-ideal factors such as random noise, dynamic interference, and channel-to-channel mismatch. The clock jitter mismatch is a mismatch between channels, and it directly degrades the SNR metrics in modulation methods mentioned earlier.

PCB-mounted components can also introduce a lot of thermal noise and electromagnetic interference (EMI). EMI rejection is closely related to the EMI source, place, routing, shielding and filtering – most of which are difficult to control. Fast protocol speed, a complex environment, and higher switching power supply energy can also contribute to EMI. In-channel clock jitter error can degrade the accuracy of the sampling instant and therefore the sampling accuracy.

Additionally, the down-conversion and the mixer also need careful design.

Some manufacturers implement entire DDCs in either FPGAs or ASIC digital signal processor (DSP) chips. Although some perform well, they are not as economical as alternatives.

Such difficulties can be improved significantly through use of integrated designs. The overall approach is to digitize everything possible, with discrete components only handling functions that cannot be defined through software.

To develop an integrated SDR, high-speed, high-precision, low-power ADCs with dynamic performance and integrated features are ideal for low IF and some bandpass high IF receiver applications. An example is the MCP37Dxx ADC series from Microchip Technology. It offers 16-, 14-, and 12-bit resolution, saving power and supporting a sampling rate up to 200 MHz. It also allows input signal bandwidth up to 500 MHz. The MCP37Dxx has built-in features that do not require a FPGA or dedicated DSP. These include DDC, NCO, a digital decimation filter, a noiseshaping requantizer, gain adjustment, and offset adjustment. DDC can be used with the decimation and quadrature output (I/Q data) option. It offers flexibility in SDR radio system designs, minimizes system cost and helps improve SNR beyond conventional resolutions. It supports up to eight input channels with input multiplexers. In dual or octal mode, the fractional delay recovery (FDR) function digitally deskews data between different channels so all inputs are interpolated to appear sampled at the same instant. The output data is available as full-rate CMOS or double data rate (DDR) LVDS. In some devices like the MCP37D31-200, the output also supports serial LVDS in eight-channel mode.

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REFERENCES Microchip Technology Inc. www.microchip.com Digitally enhanced high speed ADC for low power wireless applications, Thomas Youbok Lee, et al., ICMIM, IEEE, 19-21 March 2017 ww.ieeexplore.ieee.org/document/7918857/ MCP37D31-200 ww1.microchip.com/downloads/en/DeviceDoc/20005322D.pdf MCP37D11-200 www.microchip.com/wwwproducts/en/ MCP37D11-200 Software-defined radio tunes in, D. Marsh, EDN, March 2005, p. 5234 www.edn.com/design/analog/4326411/Software-defined-radio-tunes-in

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4/16/18 3:13 PM

B U L K A C O U S T I C WAV E F I L T E R S

Bulk acoustic wave filters make life easier for Wi-Fi front-end designers CEES LINKS | QORVO WIRELESS CONNECTIVITY

BAW filters help overcome the biggest challenges facing Wi-Fi front-end designs, including thermal management, interference, and RF linearity.

Smart

homes are getting smarter. So they increasingly make heavy demands on their internet routers, so much so that traffic demands are exceeding the capacity of the single-router model. Retailers and businesses are also being overwhelmed by the ever-rising need for coverage and bandwidth.

As a result, new application models are evolving. Use of multiple routers, or nodes, in the home helps service more clients and handle more data. This new mesh network model implements techniques already used in commercial buildings, hospitals and college campuses via enterprise-level systems.

Not surprisingly, the mesh networking model also boosts RF complexity within the access point. Complexity also is rising because of new communication standards and better capabilities in communication hardware. The trend has brought several IoT-related challenges that include:

S AW Ve r u s B AW o n t h e r m a l d r i f t

The need for wireless radios. Access points today incorporate more than just Wi-Fi — they also support Zigbee, Bluetooth, Bluetooth Low Energy (BLE), Thread, and narrowband IoT (NBIoT). Operators are also finding ways to reach households that previously lacked such access.

More users within each home. Homes no longer have only one or two PCs and a few phones. Today, it’s common to find several computers, TVs, smartphones, wearables, security networks, wireless appliances, and more all connected to Wi-Fi and the internet.

Additional Wi-Fi bands. Units no longer have one 2.4 GHz band and one 5 GHz band.

Now there are up to three individual 2.4-GHz and eight 5-GHz paths. The reason is the use of MIMO (multiple-input/multiple-output) and multiuser MIMO (MU-MIMO) paths within the Wi-Fi access point or node.

The thermal drift of SAW and BAW filters. If the filter drifts too much, as in the SAW figure, the RF power amp pushes out more power to compensate for the insertion loss.

This consumes more current and reduces system efficiency.

Shrinking size and expanded functions. Wi-Fi manufacturers are making Wi-Fi units smaller, sleeker, more decorative, and less obtrusive. They’re also making some units all-weather or adding functions such as night-light capability.

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S p e c t r u m exa m p l e o f A s i a a n d E M E A

The additional RF chains generate more heat within the access point. They also make thermal management more challenging for Wi-Fi front-end designers. The higher temperatures also make RF tuning more challenging, especially when multiple RF chains must fit in the same box that once housed a single-channel Wi-Fi. In a nutshell, temperature affects three RF front-end (RFFE) components: power amplifiers (PAs), RF switches and low noise amplifiers (LNAs), and filters. Engineers often balance among linearity, power output, and efficiency in each of the RF chains.

Using optimized, highly linear power amplifiers or front-end modules (FEMs) optimizes system efficiencies, creating less overall heat.

This practice also reduces processing inefficiencies. Wi-Fi design trends affecting power amplifiers include time division duplexing (TDD), optimizing error vector magnitude (EVM), higher modulation schemes, and efforts to moderate overall current draw on the system processor.

In the RF switch, insertion loss can also generate excess heat.

When insertion loss rises and signal strength is low, the PA works harder to compensate and push higher outputs, which degrades efficiency. And less efficiency means more heat from the device.

Use of high-linearity, low-loss switches keeps the insertion loss within specifications across the entire band.

Receive throughput depends greatly on LNA gain and noise figure. So although the LNA doesn’t contribute significantly to heat generation, heat degrades LNA noise figure, which can in turn drastically affect throughput.

BAW VS. SAW FILTERS As more LTE bands squeeze into the crowded global RF spectrum, the space between them is shrinking. In some cases, the transition between the passband and stop-band is as small as 2 MHz. This makes it almost impossible to meet requirements using traditional filter technologies. That’s because the variation in filter response, which is dominated by temperature drift, can exceed the width of the transition band itself. The result is unacceptable interference, high insertion loss, or both.

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Several LTE bands — Bands 40, 7 and 41 — are close to the Wi-Fi band channels.

Leakage into the adjacent Wi-Fi radio band is probable at both the high and low end of the 2.4 GHz band.

The nearby figure illustrates the thermal drift of SAW and BAW filters. Temperature shifts can cause high insertion loss on the band edges, which could, in turn, cause a low output (gain or POUT) response from the RFFE. If the filter drifts too much (as in the SAW figure), the PA pushes out more power to compensate for the insertion loss. This draws more current and reduces system efficiency.

Although surface acoustic wave (SAW) filters are well suited for applications up to about 1.5 GHz, bulk acoustic wave (BAW) filters generally perform better with lower insertion loss at higher frequencies. BAW filters are inherently less sensitive to temperature changes than standard SAW filters. Diplexers, bandpass filters, and coexistence filters that use BAW technology with lower temperature drift help mitigate insertion loss and lead to good product thermals.

The circuits implementing different communication standards can also interfere with each other, leading to connectivity problems for users. For example, Bluetooth, Zigbee and Z-Wave are communication schemes for short and mid coverage ranges; Wi-Fi, 3G/4G LTE and 5G are standards operating at higher power levels and short and long ranges. And unlicensed (particularly within the IoT realm) networks are becoming more important as constrained wireless communications offload data to continually expand capacity. The challenge is to keep all these licensed and unlicensed bands and multiple protocols working in each other’s presence without interference.

Interference can arise within a device or between devices, including between wireless carrier signals or between circuits implementing different wireless standards. The most common interference scenario is Bluetooth and LTE with WiFi because these technologies are so widespread.

There is also a possibility that the system’s multiple antenna architectures can interfere with each other. As a result, the coupling between the affected antennas (antenna isolation) is compromised. The foreign transmit (Tx) signal

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B U L K A C O U S T I C WAV E F I L T E R S

Bluetooth and Wi-Fi transmit in different ways using differing protocols, but they operate in the same frequency ranges. As a result, when Wi-Fi operates in the 2.4 GHz band, Wi-Fi and Bluetooth transmissions can interfere with each other.

I S M , W i - Fi a n d B l u e t o o t h c h a n n e l f r e q u e n c i e s

increases the noise power at the affected receiver, which degrades the signal-tonoise ratio. The receiver (Rx) sensitivity drops, which causes what engineers call “desensitization.”

Desensitization is a degradation of the sensitivity of the receiver caused by external noise sources. It results in dropped or interrupted wireless connections. Desensitization isn't a new problem — early radios encountered receiver desensitization when other components became active — but now it’s particularly troublesome for wireless technologies, including smartphones, Wi-Fi routers, Bluetooth speakers and other devices.

There are three primary desensitization scenarios. First, two radio systems occupy bordering frequencies, and carrier leakage occurs. Second, the harmonics of one transmitter fall on the carrier frequencies used by another system. And finally, two radio systems share the same frequencies.

Several LTE bands — Bands 40, 7 and 41 — are close to the Wi-Fi band channels. Leakage into the adjacent Wi-Fi radio band is quite probable at both the high and low end of the 2.4-GHz band. Without proper system design, the cellular and Wi-Fi channels 1 and 13 can interfere with each other's transmissions and receive capability.

Bluetooth and Wi-Fi transmit in different ways using differing protocols, but they operate in the same frequency ranges. As a result, Wi-Fi and Bluetooth transmissions can interfere with each other when Wi-Fi operates in the 2.4 GHz band. Because Bluetooth and Wi-Fi radios often operate in the same physical area (such as inside an access point), interference between these two standards can degrade the performance and reliability of both wireless interfaces.

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BAND EDGES AND WI-FI COEXISTENCE One way governments have tried to help consumers is by regulating the emissions and spectrum of electronic devices and requiring consumer products to undergo compliance testing. In the U.S., for example, the Federal Communications Commission (FCC) dictates that most RF devices undergo testing to demonstrate compliance to its rules. The agency enforces strict band edges by requiring steep skirts on the

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lower and upper Wi-Fi frequencies, to help with coexistence with neighboring spectrum.

There are two ways for Wi-Fi access points to meet this FCC requirement: Back off the power level on Wi-Fi channel 1 and 11, because they're at the edge of the Wi-Fi spectrum; and use filters with extremely steep band edges.

High-Q BAW bandpass filters offer features that help Wi-Fi front-end designers overcome interference challenges, including extremely steep skirts that simultaneously exhibit low loss in the Wi-Fi band and high rejection in the band edge and adjacent LTE/ TD-LTE bands. These filters are also physically small and can resolve coexisting Wi-Fi and LTE signals that are within the same device or near one another.

BAW filters demonstrate good power handling capabilities, allowing for implementation into high-performance, high-power access points and small cell base stations. These filters address the stringent thermal challenges of MU-MIMO systems without compromising harmonic compliance and emissions performance.

This quality is critical to realizing reliable coverage across the full allocated spectrum.

It is useful to look more closely at the three ways that high-Q BAW filters make a difference for band edges.

First, BAW devices have lower insertion loss, steeper band edges and better temperature stability than SAW technology at Wi Fi frequencies. At the higher bandwidths employed in standards like Wi-Fi, SAW devices can suffer from insertion losses that exceed those of BAW because acoustic energy radiates into the bulk of the SAW substrate. As frequency rises, high-Q BAW is a good option for filter designs because it doesn’t suffer from this bulk radiation loss effect. Also, BAW maintains steep skirts at band

edges; SAW cannot match this performance at these higher frequencies.

Second, BAW filtering can help engineers provide seamless transitioning between interfering bands. Band-edge response is better with a filter than without it. BAW filters allow designers to push the limit on RF front-end output power while meeting regulatory requirements for power spectral density. This means band-edge BAW filtering lets operators and manufacturers deliver high-speed data and greater bandwidth by using spectrum that might be lost without filtering.

Third, high-Q BAW band-edge filters can extend the range in channel 1 and 11 by a factor of two or three. WiFi designers normally must set the entire unit power to whatever the lowest band-edge-compliant power is for all channels. So, staying with the FCC example, if the compliant power at channel 1 is +15 dBm but channel 6 can achieve +23 dBm, the designer sets the entire power control scheme to +15 dBm. Use of band-edge filtering allows designers to set the power scheme to much higher powers, thus making it possible to use fewer RF chains.

CPE developers who don’t use band-edge filtering have difficulty meeting the FCC requirements on Wi-Fi band channels 1 and 11. In contrast, use of high-Q BAW band-edge filters allow the CPE designer to keep the power level the As frequency rises, high-Q BAW is a good option for filter designs because it doesn’t suffer from bulk radiation losses that affect SAW filters. Also, BAW maintains steep skirts at band edges; SAW cannot match this performance at these higher frequencies.

BAW ve r s u s S AW t e c h n o l o g y

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The Total Package

Complete System Solutions for Your Wireless Design

Adding wireless connectivity to your product is exciting, and Microchip has you covered every step of the way with each piece of the design. Whether you want to add a Wi-Fi® sensor to your water tank or you just want the ease and control of connecting your product to a smartphone via Bluetooth®, we have the complete solution for your design. With a broad wireless portfolio, the industry’s largest microcontroller selection, and software stacks with built-in security that enable cloud connectivity, Microchip is a one-stop-shop for a complete wireless solution.

To speed up development, we offer multiple reference designs and design ideas to start building from. These reference designs are great tools for showing you the right components to start with and real-life use cases for further inspiration and ease of design. And with our free software available on MPLAB® Harmony and Atmel Studio, development has never been easier.

www.microchip.com/wireless The Microchip name and logo, the Microchip logo and MPLAB are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. All other trademarks are the property of their registered owners. © 2017 Microchip Technology Inc. All rights reserved. 8/17 DS70005341A

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FCC r e s t r i c t e d b a n d e d g e w i t h a n d w i t h o u t BAW f i lt e r

Band-edge response is better using a filter than without it. Filtering allows designers to push the limit on RF front-end output power while meeting regulatory requirements for power spectral density.

same throughout all the channels (1 – 11).

To paint the picture, consider the difference in user experience with and without band-edge filters.

to the point where buffering occurs. Why? Because to meet the FCC requirement, the CPE unit must back off its power in channel 1 so it doesn't interfere with adjacent cellular bands.

Without band-edge filters: Assume you’re in a house with several individuals using Wi-Fi and mobile phones.

You’re on Wi-Fi using channel 5, streaming a football game and experiencing no buffering or interruption.

But then new mobile users arrive and begin to consume your channel 5 Wi-Fi space. The CPE unit adjusts and bounces you to channel 1 to free up more space on channel 5. If the Wi-Fi unit lacks band-edge filters, your Wi-Fi strength and streaming degrade

With band-edge filters: If the CPE unit had been designed with band-edge filters, channel 1 and 11 would not be compromised, and the power level would not require back-off. The streamed football game comes through without any buffering.

Wi - Fi / LT E s y s t e m m o d e l s ( w i th / w i th o u t b a n d e d g e f i lt e r s )

All in all, system capacity is an increasingly important criterion in Wi-Fi developments, together with thermal management and avoiding interference. BAW filters are inherently less sensitive to temperature change than standard SAW filters, and they generally deliver superior performance with less insertion loss at higher frequency levels. BAW filters can also overcome interference challenges, primarily because of their extremely steep skirts that exhibit low loss in the Wi-Fi band and high rejection in the band edge and adjacent LTE/TD-LTE bands.

REFERENCES Qorvo BAW filters www.qorvo.com/innovation/ technology/baw

Customer premises equipment designed with band-edge filters (right) need not compromise Wi-Fi channels 1 and 11 when new users arrive, so the Wi-Fi unit doesn’t need to back off its power level to stay within FCC requirements. Football fans can watch streamed games without any buffering.

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M O R E A C C U R AT E C H E C K - U P S

More accurate check-ups for battery health A new technique may eliminate the guesswork

ANDREAS MANGLER | RUTRONIK ELEKTRONISCHE BAUELEMENTE GMBH OLFA K ANOUN | CHEMNITZ UNIVERSITY OF TECHNOLOGY THOMAS GÜNTHER | CHEMNITZ UNIVERSITY OF TECHNOLOGY

involved in figuring out how much life batteries have left.

As

Li-ion batteries age, their performance deteriorates. It takes complex instrumented lab tests to determine how quickly and to which degree battery performance degrades. But recently, researchers at Chemnitz University of Technology devised a way to make a quick and precise diagnosis. The technique ensures the reliable determination of Li-ion state-of-health (SoH) and remaining useful life (RUL).

The state of health (SoH) of a battery deteriorates over time because of both calendric and cyclic aging. Calendric aging refers to the fact that the battery ages without being used, simply due to time. This process is influenced, in particular, by the ambient temperature. Cyclic aging refers to what happens because of charge/discharge cycles. Though it depends on the type of use, it is mainly a function of the operating cycles, the charging/discharging

stroke, the end-of-charge voltage, and the strength of the charging and discharging currents. The upper max for the number of charge/ discharge cycles is determined by the type and quality of the batteries and the temperature.

Li-ion SoH has a direct effect on the capacity of the overall system. In electric cars, the vehicle range and good acceleration depend on the battery. In safety-relevant applications, such as backup systems or mobile medical applications (such as defibrillators), it is essential to know whether the battery will supply enough energy when it is needed.

Besides the present state of charge (SoC), the real determining factor here is the age of the battery. Based on complex chemical reactions inside the battery, there is a gradual degradation in performance over time, and the battery’s SoH consequently suffers. The SoH reflects the ratio between the battery’s remaining maximum practical capacity and its theoretical capacity -- i.e. a 100-Ah battery with a SoH of 80% has a residual capacity of 80 Ah. It is difficult to determine or to predict how quickly a battery or the individual cells of a battery pack will age. On one hand, the capacity cannot be measured directly; on the other, the aging process is influenced by several factors, including the individual condition of the battery, the charging behavior, and the temperature.

The only way to evaluate battery life is to determine the SoH. Depending on its

A demonstrator that implements the battery evaluation technique. It uses an evaluation board containing an STM32F407 microcontroller from ST Microelectronics

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application, the battery end-of-life is reached with a SoH of between 70 and 80%. The battery then frequently swaps its ‘first life’ for a ‘second life.’ That is, it is moved into an application that demands less capacity. For instance, EV batteries often have a second life as stationary energy storage systems for PV units. The remaining maximum capacity of the battery in the respective application is referred to as the remaining useful life (RUL).

It has been impossible to simply measure the remaining capacity to determine the SoH and RUL. Relatively complex and often inaccurate procedures presently gauge these parameters. Before installing the battery, a vast array of data is collected in the lab to characterize the battery. Algorithmic calculations are used to create a lookup table or an empirical model that describes the battery at defined working points and in various applications. The data are saved in the battery management system and the battery end-of-life is merely predicted by comparison with the stored data. The actual state of the battery in operation is, in fact, not measured.

Needless to say, the base data for the battery management system remains inaccurate.

A coulombmeter, which measures the charge flowing in and subtracts the charge flowing out, often serves as a means to determine battery capacity. The data are then compared with a model to draw conclusions about the SoH and the RUL. However, even this method provides relatively inaccurate values; the predicted end-of-life may vary considerably from the actual situation.

The result: To ensure a guaranteed battery life, manufacturers must install more battery cells as a safety buffer. Alternatively, they must scale back the parameters that depend on the state of the battery such as the vehicle range and the battery warranty period. In neither case is the battery capacity utilized fully.

Addressing such problems, the Professorship for Measurement and Sensor Technology at Chemnitz University of Technology developed a way to precisely diagnose a fully operational battery in just a few minutes. It also provides reliable online information about the battery SoH and RUL. The technique employs measurements based on impedance spectroscopy. Impedance spectroscopy helps assess battery internal processes such as charge transfer, electrode degradation, and diffusion. To do so, the battery is excited with varying alternating current supply potential. The resulting battery voltage and the excitation current can be used to calculate the impedance, allowing conclusions about the state of the battery.

Impedance spectroscopy is basically a way to characterize changes at the surfaces of active elements within a battery. It exploits Faraday’s laws of electrolysis to size up chemical processes in terms of electrical measurements.

The electrochemical impedance is the response of the cell to an applied potential.

The frequency dependence of this impedance can reveal underlying chemical processes. And knowledge of the chemical processes can, in turn, reveal the battery SoH.

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A graph of battery impedance, the real part of battery impedance, and applied frequencies illustrates the principle of impedance spectroscopy. Rutronik supports this research by supplying electronic components and development tools used in master’s and bachelor’s theses. Rutronik also distributes Samsung SDI Li-ion batteries, giving it close links to the battery manufacturer and making it a source of knowledge about battery cells and battery management systems.

The main factor that complicates electrochemical impedance measurements is that electrochemical systems have an extremely nonlinear response. So the approach is to interrogate the battery impedance using a small (often from 1 to 10 mV) ac ripple riding on a dc potential. A measurement is recorded at each of many ripple frequencies to approximate the battery response in a piecewise linear fashion. The ac frequency is varied because the system response as a function of the perturbation frequency can reveal information about the internal battery dynamics. (For example, a process that depends on the diffusion of reactants toward or away from a surface such as that of an electrode has a particular low-frequency character that depends on the chemical reaction rate and a diffusion coefficient.)

Because the battery is non-linear, its current response will contain harmonics of the excitation frequency. It is possible to use this harmonic information in several ways. For example, the presence or absence of significant harmonic response gives a measure of the system linearity. It is also possible to apply larger-amplitude excitations and then measure the harmonic response to estimate the curvature in the cell's current-voltage curve.

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2018 Flexible installation via rear or side panel mounting, or on DIN rail.

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INTERNET OF THINGS HANDBOOK

The process steps of impedance spectroscopy: A signal of a specific frequency is applied, and current is measured over time. The resulting time series is converted to a frequency spectrum and analyzed for harmonic content. These steps are repeated at numerous frequencies. The resulting information is tabulated to yield a plot of battery impedance.

The necessity for analyzing harmonics implies that the measurement apparatus needs some sort of FFT capability. Additionally, because the internal impedance of today’s Li-ion cells can be less than 1 mΩ, the measuring methods and measurement hardware must have special capabilities. It takes expensive and precise instrumentation to work with the low impedance values, as well as large memory capacities to record the wide frequency ranges involved.

Consequently, the method has only been applied in laboratory conditions where the process is usually monitored by an engineer.

To apply impedance spectroscopy in mobile systems, scientists at Chemnitz University of Technology have optimized the method to such a degree that a chip

with limited memory and processing power can map the procedure without the need for additional signal generators.

The battery itself or energy from another stack serves as the source of power, thus reducing the related hardware costs enormously. The large frequency range involved forced the use of multi-spectral methods to cut the measuring time.

All calculations can take place during the measurement itself thanks to innovative algorithms. For instance, it was possible to reduce the memory capacity of the controller to less than 500 kbytes for intermediate storage of the measured data. In addition, the measuring period shortened to roughly five minutes. The short measurement time makes it possible to repeat measurements in defined cycles during operation, e.g. in certain operating

conditions. These features also help satisfy the development requirements for controllers in the automotive sector.

The prototype hardware developed at the Professorship for Measurement and Sensor Technology can be used to diagnose four battery cells simultaneously. However, the hardware can, in principle, be scaled as required to larger systems. Moreover, the use of an embedded controller makes the technique economical and compact.

REFERENCES Rutronik www.rutronik.com/article/ detail/News/determining-thestate-of-health-of-batteriesquickly-and-precisely/

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WHY THE INDUSTRIAL IoT

Why the Industrial IoT needs industrial batteries Advanced lithium battery technology delivers long-life power and high pulses to expand remote wireless connectivity throughout the Industrial Internet of Things.

SOL JACOBS | TADIRAN BATTERIES

The

Industrial Internet of Things (IIoT) is largely influenced by advanced wireless devices and sensors. To a large extent, the rapid expansion of industrial connectivity is being driven by industrial-grade batteries that deliver reliable power to remote locations and extreme environments.

For example, the typical oilfield is now equipped with 30,000 sensors. Having to hard-wire all these sensors would be time-consuming and prohibitively expensive.

In addition, many of these sensors interface with the HART (Highway Addressable Remote Transducer) protocol, the traditional industry standard platform that adapts decades-old analog telephone caller ID using 4-20-mA analog wiring. Unfortunately, most HART-enabled devices were never fully integrated, largely for financial reasons, as it costs roughly $100/ft. to install any type of hard-wired device, even a basic electrical switch.

In remote locations and extreme environments, the costs associated with hard-wiring grows exponentially because of added expenses, including labor and materials, travel, and regulatory/permitting requirements. If all 30,000 wireless sensors in an oilfield connected via WirelessHART, all these cost barriers would disappear.

Each wireless application is unique, so different batteries are best for different applications. If a remote wireless device requires long operating life and only draws microamps daily, it will likely be powered by an industrialgrade primary (non-rechargeable) lithium battery. Conversely, if the device draws enough average daily current to exhaust a primary battery in short order, it may be better suited for an energy harvesting device feeding its harvested energy to a Lithium-ion (Li-ion) rechargeable battery.

Remote industrial wireless applications that require long-term deployment in hardto-reach places or extreme environments typically cannot use consumer grade batteries. For example, because of their high self-discharge, alkaline batteries often last for only two or three years. Alkaline batteries also use a water-based chemistry that is prone to freezing, making them best suited for use indoors

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Industrial grade Li-ion batteries can operate for up to 20 years and deliver 5,000 full recharge cycles. They also feature an expanded temperature range of -40 to 85°C and the ability to deliver high pulses.

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in moderate temperatures where they can easily be replaced.

The low initial purchase price of a consumer-grade battery can also be misleading. It does not reflect the true long-term cost of ownership which must account for all the costs of frequent battery replacements. These costs include that of the batteries themselves, ongoing labor costs, and the potential for system downtime and loss of data.

The selection of an industrial grade battery can be a complex process involving numerous technical considerations that include: energy consumed in active mode (including the size, duration, and frequency of pulses); energy consumed in ‘stand-by’ mode (the base current); storage time (as normal self-discharge during storage diminishes capacity); thermal environments (including storage and in-field operation); equipment cut-off voltage (as battery capacity is exhausted, or in extreme temperatures, voltage can drop to a point too low for the sensor to operate); battery self-discharge rate (which can be higher than the current drawn from average daily use); and cost.

Other key considerations include battery reliability. Is the remote sensor in an inaccessible spot where battery replacement is difficult or impossible? Is loss of data due to battery failure not an option?

And does the self-discharge rate of the battery exceed the energy lost through average daily consumption? If so, initial battery capacity must be as high as possible.

Size and environment can be considerations as well. If miniaturization is required, batteries with higher capacity and energy density pack more energy into a smaller footprint. If batteries with higher voltage can be specified, it may be possible to outfit the application with fewer cells. And if the device will see extremely hot

or cold temperatures, the battery must be chosen to handle the range.

Finally, lifetime costs are a factor. Future costs to consider include labor and materials to replace batteries, and the possible risks associated with battery failure.

PRIMARY LITHIUM BATTERIES Lithium battery chemistry is widely preferred for long-term deployments thanks to its high intrinsic negative potential, which exceeds that of all other metals. As the lightest nongaseous metal, lithium offers the highest specific energy (energy per unit weight) and energy density (energy per unit volume) of all available battery chemistries. Lithium cells operate within a normal operating current voltage (OCV) range of 2.7 to 3.6 V. The absence of water also allows lithium batteries to endure extreme temperatures without freezing.

Numerous primary lithium chemistries are commercially available, including iron disulfate (LiFeS2), lithium manganese dioxide (LiMNO2), lithium thionyl chloride (LiSOCl2), and lithium metal oxide chemistry.

Lithium iron disulfate (LiFeS2) cells are relatively inexpensive, used mainly to deliver high pulses required to power a camera flash. LiFeS2 batteries have performance limitations that include a narrow temperature range (-20 to 60°C), a high annual self-discharge rate, and crimped seals that may leak.

Lithium Manganese Dioxide (LiMNO2) cells, including the widely used CR123A, provide a space-saving power source for cameras and toys, as one 3-V LiMNO2 cell can replace two

Co m p a r i s o n o f p r i m a r y l i t h i u m c e l l s LiSOCL2

LiSOCL2

Li Metal Oxide

Li Metal Oxide

Bobbin-type with Hybrid Layer Capacitor

Bobbin-type

Modified for high capacity

Modified for high power

Energy Density (Wh/1)

1,420

1,420

370

185

600

650

650

Power

Very High

Low

Very High

Very High

Low

High

Moderate

Primary Cell

LiFeS2

LiMnO2

Lithium Iron Disulfate

CR123A

Voltage

3.6 to 3.9 V

3.6 V

4.1 V

4.1 V

1.5 V

1.5 V

3.0 V

Pulse Amplitude

Excellent

Small

High

Very High

Low

Moderate

Moderate

Passivation

None

High

Very Low

None

N/A

Fair

Moderate

Performance at Elevated Temp.

Excellent

Fair

Excellent

Excellent

Low

Moderate

Fair

Excellent

Fair

Moderate

Excellent

Low

Moderate

Poor

Performance at Low Temp.

26

Alkaline

Operating life

Excellent

Excellent

Excellent

Excellent

Moderate

Moderate

Fair

Self-Discharge Rate

Very Low

Very Low

Very Low

Very Low

Very High

Moderate

High

Operating Temp.

-55°C to 85°C, can be extended to 105°C for a short time

-80°C to 125°C

-45°C to 85°C

-45°C to 85°C

-0°C to 60°C

-20°C to 60°C

0°C to 60°C

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Here’s how primary lithium cells stack up in terms of performance qualities.

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WHY THE INDUSTRIAL IoT

Co m p a r i s o n o f c o ns u m e r ve r u s i n d u s t r i a l l i - i o n r e c h a r g a b l e b at t e r i e s Here’s how industrial and consumer-oriented lithium cells distinguish themselves.

1.5-V alkaline cells. LiMNO2 batteries can deliver moderate pulses but suffer from low initial voltage, a narrow temperature range, a high self-discharge rate, and have crimped seals.

Lithium thionyl chloride (LiSOCl2) batteries are constructed two ways: bobbin-type and spiral wound. Bobbintype LiSOCl2 batteries are preferred for long-term deployments that draw low average daily current, including automatic meter reading/advanced metering infrastructure (AMR/AMI), M2M, SCADA, tank level monitoring, asset tracking, environmental sensors, and applications that involve extreme temperature cycles.

Bobbin-type LiSOCl2 batteries feature the highest capacity and highest energy density of any lithium cell, along with an extremely low annual self-discharge (less than 1% per year for certain cells), thus enabling up to 40-year battery life.

Bobbin-type LiSOCl2 batteries also deliver the widest possible temperature range (-80 to 125°C) and feature a superior quality glass-to-metal hermetic seal.

The annual self-discharge rate of a bobbin-type LiSOCl2 battery can vary significantly based on the method of manufacturing and the quality of the raw materials. For example, a superior-quality bobbin-type LiSOCl2 cell can have an annual self-discharge rate as low as 0.7% and can retain over 70% of its original capacity after 40 years. By contrast, an inferior-quality bobbin-type LiSOCl2 cell can have a self-discharge rate of up to 3% per year, losing 30% of its available capacity every 10 years, making it impossible to realize a 40-year battery life.

The impact of a higher self-discharge rate may not become apparent for years. Consequently, applications that need a battery with a long operating life, especially in extreme environments,

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TLI-1550 (AA)

Li-Ion

Industrial Grade

18650

Diameter (max)

[cm]

1.51

1.86

Length (max)

[cm]

5.30

6.52

Volume

[cc]

9.49

17.71

Nominal Voltage

[V]

3.7

3.7

Max Discharge Rate

[C]

15C

1.6C

Max Continuos Discharge Current

[A]

5

5

Capacity

[mAh]

330

3000

Energy Density

[Wh/l]

129

627

Power [RT]

[W/liter]

1950

1045

Power [-20C]

[W/liter]

> 630

< 170

Operating Temp

deg. C

-40 to +90

-20 to +60

Charging Temp

deg. C

-40 to +85

0 to +45

Self Discharge rate

[%/Year]

<5

<20 ~300

Cycle Life

[100% DOD]

~5000

Cycle Life

[75% DOD]

~6250

~400

Cycle Life

[50% DOD]

~10000

~650

Operating Life

[Years]

>20

<5

require some thorough due diligence: Designers should demand fully documented long-term test results, in-field performance data, as well as customer references from potential battery suppliers.

Specially modified bobbin-type LiSOCl2 batteries can be adapted to handle extreme temperatures. An example is where wireless sensors monitor the transport of frozen foods, pharmaceuticals, tissue samples, and transplant organs at temperatures as low as -80°C. Bobbin-type LiSOCl2 batteries can also handle extreme heat.

For example, Awarepoint, a maker of real-time location systems, chose LiSOCl2 batteries for use in active RFID tags on medical equipment. The tags could go through autoclave sterilization, where temperatures can reach 135°C, without having their batteries removed.

Long-life bobbin-type LiSOCl2 batteries are almost exclusively utilized in meter transmitter units (MTUs) for AMR/ AMI applications. The extended battery life of a bobbin-type LiSOCl2 cell is valuable

4 • 2018

to utility metering because a large-scale battery failure can disrupt customer billing systems and disable remote service startup and shut-off capabilities. Fear of such chaos could force a utility company to invest millions of dollars to prematurely replace batteries so as not to jeopardize data integrity.

HIGH PULSES AND TWO-WAY WIRELESS The rapid growth of the IIoT has boosted the use of remote wireless devices that require high pulses to support two-way wireless communications. A standard bobbin-type LiSOCl2 battery features a low rate design and thus cannot easily deliver the high pulses needed for two-way wireless communications. This obstacle can be overcome simply by combining a standard bobbin-type LiSOCl2 cell with a patented hybrid-layer capacitor (HLC).

The standard LiSOCl2 cell delivers low daily background current when the device is in stand-by mode, while he HLC works like a rechargeable battery to deliver periodic high pulses.

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INTERNET OF THINGS HANDBOOK

Many consumer electronics products employ supercapacitors to deliver high pulses. Supercapacitors are not generally recommended for use in industrial applications because they have serious drawbacks, including short-duration power, linear discharge qualities that do not allow for use of all the available energy, low capacity, low energy density, and high annual self-discharge rates (up to 60% per year). When supercapacitors are linked in series, they require the use of cell-balancing circuits which add cost, increase size, and draw additional current.

High pulse requirements exhaust more energy, so longterm deployments invariably need to conserve as much energy as possible. There are three usual approaches to minimize power demand: by employing a low-power communications protocol (i.e. ZigBee, WirelessHART, LoRa, etc.); by intelligent circuit design and assembly, including the use of low-power microprocessors and components; and by maximizing the amount time spent in the stand-by state while minimizing energy consumption during data interrogation and transmission.

A growing number of IIoT applications are powered by energy harvesting devices in combination with Li-ion rechargeable batteries that store the harvested energy.

While photovoltaic (PV) panels are a common form of energy harvesting, other methods can be used to extract small amounts

of energy from equipment vibration, temperature variances, and ambient RF/EM signals. Energy harvesting is especially beneficial for applications that draw an average daily current that would prematurely exhaust a primary lithium battery.

Common examples include solar-powered animal tracking devices that enable ranchers to continually track cattle herds, and solar-powered parking meters that both enable automated fee collection and identify open parking spots to help reduce pollution and traffic congestion.

Consumer-grade rechargeable Li-ion cells work well if the device is easily accessible, requires a maximum operating life of five years and 500 recharge cycles, and operates within a moderate temperature range (0 - 40°C), with no high pulse requirements. However, an industrial grade rechargeable Li-ion battery will likely be necessary if the application involves a longterm deployment in a remote location or extreme environment, or if high pulses are required.

Industrial grade Li-ion batteries can operate for up to 20 years and deliver 5,000 full recharge cycles and feature an expanded temperature range of -40 to 85°C, including the ability to deliver high pulses (5 A for a AA-size cell). These ruggedly constructed cells also feature a hermetic seal that offers superior safety protection versus consumer-grade rechargeable Li-ion batteries.

REFERENCES Tadiran Batteries http://www.tadiranbat.com/

Specially modified bobbin-type LiSOCl2 batteries can be specially adapted to handle extreme temperatures. An example is where wireless sensors monitor the transport of frozen foods, pharmaceuticals, tissue samples, and transplant organs at temperatures as low as -80°C.

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INTERNET OF THINGS HANDBOOK

Bluetooth Low Energy processors foster innovations in healthcare Applications for fitness tracking and remote health monitoring have grown to such an extent that chip makers have developed SoCs optimized for counting heart beats and calculating glucose levels.

STEVEN DEAN ON SEMICONDUCTOR

Smart

wearables for mobile health (mHealth) applications are an exciting area. They can monitor vital signs and drug delivery and then send data to remote healthcare professionals. The result is better patient care and freedom as well as less need for hospital visits for routine checks. Bluetooth Low-Energy technology radio SoCs, such as ON Semiconductor's RSL10, can make low-power mHealth apps a backbone of the modern medical market.

Supported by innovative ICs, the number and variety of mHealth products are both growing quickly. SoCs, backed by design tools, can help designers working in this sector launch exciting products to market with greater speed and ease.

New applications are emerging rapidly in the consumer medical and overthe-counter space. These include pulse oximeters and even single-lead EKGs to accompany the more common consumer medical devices such as blood pressure monitors, heart rate monitors, blood glucose meters, thermometers and weight scales. Other, more clinically-oriented devices for professional use include portable ECG/EKG machines, multi-parameter patient monitors, and other forms of mobile patient monitoring.

CHALLENGES FACING DESIGNERS A significant portion of the mHealth market involves converting existing systems to become mobile, connected versions. Often however, medical device manufacturers hesitate to write off a perfectly functional system and replace it with a brand new connected equivalent. Instead, they will often add wireless connectivity to the existing design.

Consumers and patients alike expect a lot of convenience and usability in modern mHealth devices. On one hand, they want something that gives accurate readings and which is intuitive and easy to use. But these features can boost the size, weight and battery drain. On the other hand, they value ultra-convenient portable devices that can last several days between battery charges. Reconciling these diametrically opposite requirements can make the designer’s task more challenging.

The right semiconductor platform can help mHealth wearable devices navigate these tradeoffs. The mHealth area has become so large that chip makers have developed SoCs specifically designed to handle IoT apps,

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B L U E TO O T H

R S L 1 0 b l o c k d i ag r a m

The RSL10 is a highly integrated, fully featured, radio SoC for mHealth applications.

wearable apps, fitness tracking, and so forth. These chips typically incorporate Bluetooth Low Energy technology as their wireless protocol. Because technology changes so rapidly, they may also incorporate a means to update operating systems and applications remotely.

To understand mHealth applications, it is useful to examine the SoCs targeting this area. One of the latest is ON Semiconductor’s RSL10 radio SoC. It offers the industry’s lowest power consumption while the device is in deep sleep and at peak receiving. The SoC incorporates a sophisticated power management system that allows operation from any voltage between 1.1 – 3.3 V, so it can work from standard coin-cell batteries.

In typical IoT mHealth applications, the device is only required to transmit for a few milliseconds with an in-built standby mode used to reduce the average current consumption to a typical value of 30 μA. When it is not transmitting, the RSL10 will go into one of several deep sleep modes that can reduce the current consumption to levels as low as 25 nA. Low power consumption has led the RSL10 to find use in implantable electronics. In one case, it replaced a MedRadio (Medical Device Radiocommunications Service) band device in implantable medical equipment. RSL10 was recently validated by the Embedded Microprocessor Benchmark Consortium’s ULPMark as the industry’s most efficient processing core, where it produced

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ON Semi article — IoT HB 04-18 V3 FINAL.indd 31

Core Profile scores more than twice as high as the previous industry leader.

In another case, and RSL10 SoC worked just from energy harvested when a person pushed a wall switch. The wall switch controlled house lighting via the RSL10’s BLE radio. Using the wireless capability to replace a conventional wall switch eliminated the need to run ac wiring to the wall switch.

One strategy SoC makers employ is to use processors that have a wide following so that designers are already familiar with the computing architecture. For example, the RSL10 integrates a 48-MHz 32-bit Arm Cortex-M3 processor. Along with the Arm processor is a 32-bit digital signal processor (DSP) in a tiny 5.5-mm2 footprint. The associated baseband hardware is Bluetooth 5 certified. It supports RF links at speeds up to 2 Mbps – around twice the data throughput of earlier devices.

Alongside the Arm Cortex-M3 core, the highly integrated RSL10 includes 76 kB of SRAM program memory, 88 kB of SRAM data memory, and 384 kB of flash memory for the Bluetooth Low Energy stack and applications. The flexible architecture allows the Arm Cortex-M3 processor to execute from SRAM and/or flash memory.

Obviously, mHealth implementations demand built-in IP protection so the contents of the flash memory cannot be copied or accessed externally after the chip has booted. The RSL10 also supports Firmware Over-The-Air (FOTA) programming, so the SoC

4 • 2018

DESIGN WORLD — EE NETWORK

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INTERNET OF THINGS HANDBOOK

B L E b a s e b a n d m a ke u p

The RSL10 Bluetooth Low Energy baseband uses both hardware and software. It is based on the use of a 2.4 GHz RF transceiver and implements the physical layer of Bluetooth Low Energy, along with proprietary and custom protocols. It is Bluetooth 5 certified and includes support for a 2 Mbps RF link.

can update its stacks and applications to take advantage of new technology as it’s released.

ON Semiconductor provides a development environment for the SoC including software, hardware, and a wide range of Bluetooth profiles for mHealth. To use Bluetooth technology, a device must be compatible with the subset of Bluetooth profiles. A Bluetooth profile is a specification regarding an aspect of Bluetooth-based wireless communication between devices. It resides on top of the Bluetooth core specification and (optionally) additional protocols. The way a device uses Bluetooth technology depends on its profile capabilities. The profiles provide standards which manufacturers follow to allow devices to use Bluetooth in the intended manner.

There are several mHealth Bluetooth profiles that RSL10 SoCs implement. They include profiles for heart rate, blood pressure, a health thermometer, glucose monitor, running speed, cycling speed, cycling power, and several others.

These profiles fall under the general category of health device profiles (HDP). They are designed to facilitate transmission and reception of medical device data. The APIs of this layer interact with the lower level Multi-Channel Adaptation Protocol (MCAP layer), but also run a service discovery protocol to connect to remote HDP devices.

HDP profiles also makes use of another profile called the Device ID Profile which enables identification of a device manufacturer, product ID, product version, and so forth.

A r c h i t e c t u r e o f a c o ns u m e r - g r ad e h e a r t m o n i t o r

REFERENCES ON Semiconductor RSL10 data sheet www.onsemi.com/pub/ Collateral/RSL10-D.PDF

One example of an mHealth application is a heart rate monitor on a chest belt. Typically, the RSL10 would sit in the chest belt where it would read pulses from a heart rate sensor. The application software would calculate a heart rate from the pulse data. The resulting measurement would pass to a heart rate profile for formatting and preparation for being passed to service layers that reformat the data, schedule the transfer, and send it to the RSL10 baseband BLE controller. The BLE radio then beams it out for reception by the BLE transceiver in a smartphone. There, the information passes back up the layers to a Bluetooth profile which sends it to application software that displays the heart rate.

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4 • 2018

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INTERNET OF THINGS HANDBOOK Monitoring a machine’s performance empowers users to detect any changes in condition, enabling components to be replaced at a planned downtime. Knowing when to replace these components makes life easier, shortens downtime, and gets your customer’s business back up and running sooner.

JEREMY KING | BIMBA

Smart technology and real-time data = productivity Which parts of your machines are critical to maintaining uptime and increasing productivity? How do you identify them? With data from IoT-based sensors, you’ll have your answers.

Suppose

you have a $10 vacuum cup. You may also own a $50,000 robot, a $15,000 multi-axis electric actuator and a $35 pneumatic actuator.

Which of these is the critical component?

For many, this is a no-brainer. If it isn’t the $50,000 robot it must be the $15,000 actuator. In reality, that actuator is designed to last 20 years and the robot is designed to last 10-15 years. Nothing in them is designed to wear. But the ten-dollar cup is made of rubber, it’s constantly going to rub against parts. It’s going to wear out. It’s going to cause down time. The $35 pneumatic actuator also has rubber seals on the inside constantly going back and forth across the cylinder body or

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4 • 2018

rod. They are going to wear out as well.

In a lot of applications, what’s critical to the production of a product, what may have the greatest impact on downtime, productivity and quality are the little pieces you might miss.

They are the sources of value.

A monitoring system to obtain real-time data is essential, because it uncovers essential insights into the life of pneumatic components and vacuum pumps. Is the supply pressure correct? Is it starting to lose vacuum? Is that ten-dollar cup starting to wear out? Will the robot start dropping $800 windshields because a rubber cup wore out? That’s what these data are for.

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INTERNET OF THINGS HANDBOOK Looking for changes in performance in real time lets users measure trends and discover earlier when that observed potential failure point is approaching peak.

There are four aspects of smart technology designers should know: »» Condition monitoring – monitor variations in component performance such as line pressure, actuator speed and seal condition to predict how many more days an actuator is going to last before it needs replacement. »» Remote monitoring – application of a data gateway to remotely obtain insights into the condition of such components as a filter regulator lubrication system, for example, whether it is starting to clog up, whether it needs to be changed, or if a vacuum pump is performing as it should. In addition to being able to access insights remotely the system can send the insights through alerts so users know sooner what’s going on in equipment. »» Machine efficiency – for an OEM machine builder, the continuing collection of real time data and insights will help them understand how to design machines to be more efficient so customers see fewer problems. »» Maximizing production – it is critical to get the most out of each piece of equipment. If machines aren’t generating reliable products, manufacturing customers won’t make money, or if they are expanding and growing, they will be sending orders to your competitors.

Ultimately, smart technology exists to maintain the life cycle of a machine. But machine builders themselves are habitually less sensitive to the life cycle. For example, it is assumed that actuators were designed to be thrown away when they are no longer useful, so users often run the actuator to failure.

That’s just business-as usual. But with run to failure, the risks include producing bad product, damaging other components, or extending downtime when the actuator fails unexpectedly.

People do this because it’s easy; they don’t have to think about it, and can keep going.

Condition monitoring enables you as service provider or the customer as user to periodically check the condition of components within equipment. Service providers and customers can find out if that cuff is wearing or discover whether that cylinder is about to fail.

Think of the machine’s life cycle as having three distinct stages. »» First, the time between design and implementation. »» Second, the time between implementation and potential failure. »» Third, the time between potential failure and observed potential failure.

Monitoring the machine’s performance empowers users to detect any changes in its condition. Once a change has been detected, components can be replaced during a planned

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4 • 2018

downtime event. Knowing when to replace these components makes life easier, shortens downtime, and gets your customer’s business back up and running sooner.

So far, we’ve focused on the critical value of actuators.

What if you want to obtain real-time data on venturi vacuum generators? These components supply compressed air in one side, which flows across and creates a vacuum. If you plot the vacuum pressure level over time, the first inflection point is when the valve is turned on; when the valve has been turned on, line pressure rises, vacuum level decreases, and remains steady. The second inflection point is when the valve has been turned off, and it returns to ambient pressure. This part of the work cycle can be monitored when you’re in the active zone.

By looking for changes in performance in the vacuum level in real time, we can measure trends and discover earlier when that observed potential failure point is approaching peak.

How does this help? It is essential to improving machine design.

Improper flow is one of the more common problems with pneumatic actuators and venturi vacuum pump applications.

Designers often place an excellent manifold valve on the systems because it’s compact, with all of its features comfortably situated right next to each other. Suppose, all of a sudden, four or five valves start to fire at the same time. The result is liable to be insufficient air supplied to the cylinder or pump causing the cylinders to slow down or misfire, or, in the vacuum curve, having something else in the system turned on causing the vacuum level to drop. If a part is moved and the vacuum level suddenly drops, the part drops. And you might not know why.

How many times in a factory is one machine running and Sensors like the Intellisense everything seems fine, and then the make it easy to gather data next day two are running and the on equipment for any IoT performance of the first machine application involving remote monitoring, machine efficiency becomes erratic? This may occur or maximizing production because of air leaks, or failure to

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4/17/18 8:27 AM

supply enough air to the right equipment. But by monitoring continuously or even intermittently users will be able to detect those changes earlier, figure out where this problem is coming from and eliminate significant work stoppages.

Once the system is installed the next goal is maximizing the component life. Cups wear out, and cylinders wear out.

How do users cope with that? With most components in life consistent operation is important. The component needs to move smoothly back and forth at the same rate all the time, never stopping.

How can designers maximize the life of a component in a factory? Address critical applications (the ones that will cause you a big headache) and important applications (if they fail it’s a pain but the users don’t want to invest the money in a monitoring system).

To maximize component life, users can perform Spot Checks of important pumps and cylinders. They can walk the plant route to take vibration measurements, pressure readings on all actuators, all vacuum pumps, and determine the performance. This will tell users when to clean filters, screens and silencers, how to ensure proper supply pressure, or to adjust a regulator to maintain proper vacuum.

Nevertheless, uses do want to detect these problems sooner. This is where continuous monitoring comes in. The limitation of spot-checking is that it is done at a specific interval; such as, is once a month enough? What happens if it fails two days after a user spot-checked it? Continuous monitoring allows users to find that out as soon as possible.

It helps them analyze trends and receive data alerts of changing conditions.

Plotting the real time pressure curves of pneumatic components is like adding an oscilloscope to a pneumatic system that, with a wobble can reveal something going on in the valve that is affecting supply pressure. Users can identify anomalies sooner, replace the valve, cylinder, or actuator, reduce downtime and maximize production.

Ultimately, of course, the goal is to minimize downtime.

Once a component fails, how can users shorten the downtime as much as possible? With an intelligent diagnostic tool, users can detect a blip in the monitoring mode, discover trends in pneumatic cylinders, or seal leakage changes. For example, if you learn that 50% of the air is blowing across the piston seal, that’s a pretty clear indicator of where the problem is. But if you apply air pressure and, while the piston seal is good and the rod seal is good, but the cylinder is still not stroking as fast as it used to, then you know there is some other system, some component, whatever it’s tied to, that might be the cause. It’s a great way to look deeper at what might be causing the problem, diagnosing it so you address the right thing.

Finally, continuous monitoring enables service providers and users to better manage source inventory. Fewer spares are needed in stock when you can plan ahead.

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REFERENCES Bimba Manufacturing Co. www.bimba.com

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INTERNET OF THINGS HANDBOOK

The checklist: 5 IoT lessons to make your IoT design project a success DAN PLACH LAIRD’S CONNECTIVITY SOLUTIONS

With IoT designs, decisions made on Day 1 can lead to success or failure. These best IoT design practices can help you avoid common missteps, which will increase the chances of success.

There

is a lot riding on the IoT products that your team is designing. Not only do that have to be completed on time and on-budget, but they have to successfully meet user expectations while also being profitable products for your company. Not every wirelessly enabled product puts a checkmark next to each of those success metrics, but you can increase the chances that your product will if you follow some best practices and avoid some common missteps that occur with IoT design projects.

LESSON #1: CERTIFICATIONS SHOULD BE A DAY 1 TOPIC Speed to market is so often the difference between a successful IoT product that hits its sales targets and an alsoran product that falls short. There’s a lot riding on hitting a completion date for a design project, and one of the biggest threats is something that too many engineering teams start thinking about too late in the process: certification.

Every wirelessly enabled product needs to achieve EMC certifications (such as FCC, CE, IC and other regulatory certifications) to be sold in the U.S. (with similar certifications in other countries), but too often an in-depth conversation about certification doesn’t happen until late in the engineering process. And too often, that conversation uncovers surprises involving the time and cost needed to conduct certifications for components that are not precertified.

To avoid that crisis at the end of a product development process, engineering teams should be talking about EMC certifications on Day 1 of a project rather than on Day 30 or Day 60 or Day 90. They should also look closely at using pre-certified radio modules, which means that the majority of the certification process is already completed and won’t lead to any delays that can come when chip-down radio solutions are used.

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LESSON #2: TALK ABOUT ANTENNAS MUCH SOONER In the same way that certification should be a topic on Day 1 in a project timeline, antenna selection and placement should also be discussed at the beginning of a project rather than once you and the engineering team are well down the road.

Here’s an all-too-common scenario: an engineering team starting an IoT project pencils in that they will use an off-the-shelf chip antenna for the project, and they think the case is closed. They think it’s a no-brainer…but then physics get in the way, because once a prototype is built, it turns out that the off-the-shelf antenna just isn’t doing the job. On paper, the chip antenna may have sufficient gain, but once it’s in the product, attenuation from the product enclosure and surrounding components can cause that performance and range to fall off a cliff.

That leads to a frantic process of changing the enclosure or layout, going with an external antenna, or commissioning a custom antenna that can rescue the project by delivering performance that meets customer needs. But that comes at the cost of delays and extra expense. The way to avoid that scenario is to have a far more in-depth conversation about antennas as early in the design process as possible. That will uncover whether or not a custom or external antenna is needed, and it will allow you to start a custom antenna design process in parallel to the rest of your development timeline—avoiding unexpected delays and costs.

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THE CHECKLIST

LESSON #3: DON’T COUNT ON WI-FI ACCESS Connectivity is another issue that can lead to product delays and unexpected costs for an IoT product. For many engineering teams, there is an assumption early in the design process that the product will use a customer’s existing Wi-Fi infrastructure. That seems like a safe assumption since Wi-Fi is ubiquitous and often cost-free, correct? Think again, because engineering teams often find out very late in the process that where IoT products will be deployed will not have access to Wi-Fi, and it causes the design team to rush back to the drawing board right as they were expecting to cross the finish line.

Here’s an example that illustrates how this can happen: A company was designing wirelessly enabled products that would go into the common areas of office buildings. These buildings always have ample Wi-Fi signals, so a decision was made to go with a Wi-Fi-only design. But it turns out that many buildings did not want these devices to tap into corporate Wi-Fi signals for security and liability reasons. So yes, there was plenty of Wi-Fi signal available, but none of it could be used for these smart devices.

To solve the issue, IoT devices may need to be designed to have both Wi-Fi and an alternate connection method like cellular.

That way, a device could use Wi-Fi when available, but have the ability to switch to cellular if needed.

LESSON #4: POWER IS KEY FOR BATTERY OPERATED IOT PRODUCTS Another issue that can result in an unsuccessful IoT design project is misjudging power consumption requirements for battery operated products. Wireless radios need power to operate, and engineering teams often neglect to run a battery analysis early in the project, incorrectly assuming that they can just select a battery at a later date. That’s a big mistake, as many times a smart product has specs that force engineers to fit the IoT capabilities into a small form factor. Squeezing an undersized battery into a product can lead to a disastrous customer experience, as replacing and even recharging batteries can cost time and money.

Engineers should think about the power source early on in an IoT project to determine space needs for a dedicated battery.

This means that some careful decisions will be needed about designing the wireless capabilities in ways that consume as little power as possible. The number one rule of thumb for keeping power consumption to a minimum is to keep “air time” as brief and infrequent as possible, because sending and receiving signals will likely be the biggest drain on the battery.

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LESSON #5: USER EXPERIENCE IS ALSO A DAY 1 DISCUSSION TOPIC: For many IoT projects today, specifications for a product are set without an in-depth understanding of how the product will be used by the actual end users. For example: It’s not uncommon for an IoT product to be designed by an engineer who is decades younger and more tech-savvy than the typical consumer who will use it. The result is a product that is confusing and frustrating to customers, who are far less technical than the designer. The specification-setting process also often misjudges exactly how a consumer plans to use the product and what they need the interface/app to do. That results in missing features or poorly designed interfaces that don’t do what an end user wants. To avoid this, the design process needs to include a much clearer understanding of the end user and how the product will actually be used…before any engineering specs are set.

Lastly, don’t forget to talk about how you’ll actually connect to the cloud at the beginning of design projects. Often, engineering teams just pencil in cloud connectivity as something to figure out later, but how the IoT product connects to the cloud and where data lives have a significant impact on a product’s cost structure and its development timeline. For example, will your company invest in dedicated on-premise servers, or use someone else’s infrastructure like Amazon AWS—which means that every piece of data will have a cost associated with it? How often will you need to access the data? How much data will be going to and from the cloud? What kind of latency do you need in order to ensure the performance and speed you are hoping to achieve? All of those questions require an early conversation about the cloud that may be far, far earlier than your engineering team typically discusses it.

REFERENCES Laird Technologies www.lairdtech.com

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How the IoT can support clean operation in mobile off-highway applications ANDERS K ARLSSON AND TRAVIS GILMER THOMSON INDUSTRIES, INC.

Although the CAN protocol continues to grow in importance among industrial automation and mobile machines, there is no doubt that the mobile off-highway market is where CAN bus version J1939 will be predominantly used.

With a common, efficient language, a CAN bus standard moves the discussion of how actuator communications will be managed to what exactly the user wants to accomplish.

This type of an IoT application increases design flexibility for mobile off-highway equipment.

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Manufacturers

of agricultural, construction and other mobile offhighway (MOH) equipment are increasingly deploying electromechanical actuators over hydraulic actuators, primarily for their simplicity and environmental benefits. But as electromechanical actuators become more intelligent through support of the Controller Area Network (CAN) bus networking standard, equipment designers have even more reasons to choose these solutions. Support for the CAN standard enables onboard intelligence that can lead to dramatic improvements in performance and maintenance.

ENVIRONMENTAL PROTECTION PLUS Hydraulic cylinders are often applied in high-force motion control in mobile equipment, but they often require fluids that are toxic to people and the environment. Chemicals such as butane, esters and organophosphates can be released from damaged equipment and during normal operations or routine maintenance. The production, transport and handling of materials prior to application also contribute risk. These concerns have opened the door for other solutions.

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Electromechanical actuators have emerged as an environmentally friendly alternative. Their performance in many heavy duty applications is comparable to that of hydraulic actuators, and with added support for the CAN bus protocol, these smart electromechanical actuators offer enhanced position control, monitoring and overall lifecycle cost savings.

SMART ARCHITECTURE The CAN protocol is an ISO standard (ISO 11898) for serial data communication. It was originally developed for automotive applications but is now also used in industrial automation and mobile machines. The MOH market predominantly uses CAN bus version J1939, which has been advanced to address the specific needs of agriculture, construction and other MOH applications.

J1939 provides a standard messaging structure for communications among network nodes under control of an electronic control unit (ECU). Every message on an actuator module representing a J1939 bus node has a standard identifier indicating message priority, data and control source. This enables plug and play interchanges of supporting devices that share the same network and comply with the messaging structure.

The image on the following page shows a typical CAN bus network using four actuators with built-in CAN bus-compliant intelligence. Each actuator has two wires, one that connects to an external power source and the other that communicates with the control source. The green box represents sensors or other components that could also be wired to the power source and the communications network, without external relays. The orange line represents the two-wire bus that transmits the low voltage of power needed for the system, and the blue line represents the two wires that are used for information exchange. This represents a dramatic improvement over conventional vehicle networks in at least the following ways: »» Power is distributed across common wiring, eliminating the need for separate wiring between each device and the power source

»»

»»

»»

Switching is embedded in the actuator electronics, eliminating the need for cumbersome external switching, connectors, and so on. All commands are executed in the actuator.

Information flows to an electronic control unit (ECU) from each device through the network bus, eliminating the need for independent connections between the devices and the ECU Other equipment that might be integrated into the system connects with the network in the same way, eliminating the need for separate wiring, controls and additional configuration

A typical CAN network supports up to 256 nodes, including multiple actuators or other devices on each node. The result is an efficient, compact system with monitoring and advanced control capability. With onboard J1939 compatibility, actuators speak the same language as the ECU, allowing communication across a shared bus. It is different from conventional electronic architectures since they require a standalone ECU for each operation. Additionally, this also enables more complex control strategies, which may include deploying the same actuator in multiple applications.

EMBEDDED POSITION CONTROL Position control with an embedded J1939-compliant actuator provides an absolute reading of position. A 14-bit signal informs the user of the actual actuator stroke position between 0.0 mm and a fully extended stroke, the accuracy of which depends on the stroke length and mechanical tolerances of a given model.

Accuracy of the signal itself, for example, could be 0.1 mm/bit, which could contribute to overall system positional accuracy of +/- 0.5 mm or better depending on tolerances in the gearing, ball nut and screw assembly.

Achieving that kind of positional accuracy on a hydraulic system can be expensive and hard to maintain. Monitoring

The Thomson Electrak HD, with its builtin J1939 CAN bus capabilities, makes it easy to build intelligent logistic systems such as the material handling train shown here.

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HOW THE IoT

the position of hydraulic actuators requires measuring the amount of fluid pumped through the lines and then using externally mounted encoders and limit switches to signal a control box when the desired points have been reached. This requires fluid to be in motion throughout the system at all times, and when pumping stops, system creep affects the position and requires recalibration. It also renders hydraulic actuation much less effective for heavy duty applications requiring consistent, highprecision position control over longer periods. CAN bus systems, on the other hand, use encoders, limit switches and potentiometers to control position, and these are designed into the system electronics to enable absolute position determination.

One key benefit of absolute position control is that it enables consistent, reliable position memory. Because many MOH machines are run by the season and might sit idle for eight or nine months, it is sometimes valuable to disconnect the battery to prevent it from draining. Without absolute position capability set at the factory, the user will have to recalibrate once they reconnect the battery.

LOW-LEVEL POWER SWITCHING Low-level power switching is standard with the J1939 protocol, allowing operators to program the actuator to extend, retract or stop smoothly using low-level electronic signals rather than a higher-energy electrical current. This improves safety by reducing the hazard of electrical shock and simplifying design by allowing lower-rated control components. Soft start capability also allows use of lower-rated power supplies and puts less stress on batteries and charging systems in vehicles.

Low-level power switching also enables controlling standard inrush to be to up to three times the full load amperage for up to 150 milliseconds. This would enable direct programmable logic controller (PLC) connections, eliminating the need for relays and the related installation issues. It also could include a sleep mode when the actuator is idle, which extends battery by reducing energy consumption and battery drain.

Dynamic braking control is another benefit of low-level power switching. Once the power is cut to an actuator, it could take between 5 and 10 mm to coast to a full stop, depending on how the actuator is mounted. Electronic actuators enable dynamic braking function, which can reduce that coast to about 0.5 mm by electronically forcing a short between motor leads inside the actuator. This improves repeatability and positioning capability.

PROGRAMMING CAPABILITY Such advanced position control and switching enable programming of the drive to perform with an infinite number of movement profiles and custom motion strategies. For example, users can program the actuator to seek forward a few millimeters or make a small set of movements back and forth to hunt down a desired position. And because the system knows what it is supposed to do and monitors performance in real time, it can flag potential variances and trigger algorithms to manage further alarms, corrections or shutdown.

With the J1939, system developers will have greater flexibility to program the sensors and internal electronics to synchronize operations among multiple actuators. For example, they can program units to vary in speed depending on load or change speed to compensate if units speed up or slow down.

Electromechanical actuators without J1939 support can provide absolute position readings, but they may require additional power and heavier wiring and relays. J1939 enables all of this to be embedded directly into the actuator and managed by embedded, low-level switching connected to the 2-wire CAN bus communications network and two power wires. This protocol not only simplifies wiring in the vehicle, it brings all of those previous external electronics into the product – and warranty – of the actuator vendor.

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Typical CAN bus network, illustrating four actuators with built-in CAN bus-compliant intelligence.

DIAGNOSTICS AND MAINTENANCE In addition to returning real-time position data to the user J1939-enabled actuators constantly return results of ongoing monitoring of temperature, current, speed, voltage and other variables, which enables advanced diagnostics and error handling. Feedback can arrive as quickly as ten times per second as the actuator constantly tests itself. If it detects a problem, such as surpassing a temperature threshold, the actuator finishes its programmed move – either fully retracted or extended – stops and sends an error flag to the computer, all in fractions of a second. Following are some of the variables that can now be monitored efficiently: »» Current. Current monitoring is a critical safety feature that shuts down the actuator on overload and eliminates the need for the traditional noisy mechanical clutch. »» Voltage. Continuous monitoring of voltage protects the actuator by preventing motion if it detects it operating in an environment outside of the acceptable range. »» Temperature. Internal temperature is monitored and, if outside the acceptable temperature range, the actuator is shut down after extending or retracting stroke. Built-in temperature compensation allows the actuator to push the rated load at lower temperatures without nuisance tripping. »» Load. Trip points can be calibrated at assembly to assure repeatable overload trip points independent of component and assembly variations. This not only assures repeatable performance, but also relieves the user of having to recalibrate in the field.

All such functionality can be embedded within the actuator, available instantly and, with the network, potentially sharable for assistance with external troubleshooting. Thomson smart actuators, for example, are a plug and play solution, easily swapped out in case of a problem. On the other hand, replacing a problematic hydraulic actuator could involve a

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service call from the manufacturer and hours or even days of disassembly, reassembly, system bleeding and testing.

Moreover, system health monitoring can occur remotely.

For example, an OEM support technician in Iowa can log in to a combine in North Dakota to diagnose a failed actuator by analyzing electronic message flags on temperature, position, current and input voltage.

ENRICHING THE DIALOGUE In many ways, optimizing the performance of an actuator is a function of the dialogue quality between the users and the device. With J1939-compatible language combined with advanced embedded electronics, users have more flexibility in telling their actuator where and how fast they want it to move, and when they want it to stop, and they will get instant feedback as to whether it has behaved accordingly.

You can engage in this kind of dialogue with a non-J1939 electromechanical actuator, but it requires more external switches and wiring. You can also engage with a hydraulic actuator, but it is a longer, more complicated conversation. By using a common, efficient language, the J1939 standard moves the discussion from how the communications will be managed to what exactly the user wants to accomplish. The end result is greater control and design flexibility, faster engineering, more efficient installation, and overall lower cost of ownership.

REFERENCES Thomson Industries, Inc. www.thomsonlinear.com

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INDUSTRIAL IoT

Industrial IoT is disrupting supply chains DAN ROBERTS | CAMBASHI LIMITED

Within the next few years, nearly every industrial company should be implement IoT projects or risk being disrupted by those that already have.

Most

industrial IoT implementations have been undertaken by early adopters trying to either improve efficiency or to get an advantage over their competitors. These projects have a number of different objectives, but typically fall into three basic categories - more efficient operations, improved customer experience or new business opportunities.

These projects are not simply restricted to manufacturing operations but run the gamut of industries. For example: More efficient operations. In retail, industrial IoT is helping deliver every supply chain manager’s dream of visibility and food security. Companies like Walmart, working with IBM, are taking the opportunity to integrate ‘blockchain’ technology for distributed ledgers to ensure tracking and food security throughout the supply network.

This is a project that spans the supply chain, with several food producers Dole, Nestlé and Unilever – and other retailers joining together to improve food traceability.

Improved customer experience.

Elekta, a Swedish manufacturer of medical technologies for treating cancer and brain disorders, uses

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connectivity and smart device technology to help differentiate its service business and expedite the way its products are serviced. Elekta partnered with PTC and GE Digital-owned ServiceMax to implement Connected Field Service. In the first year of the project, Elekta carried out more than 600 preventative actions, which translated to uninterrupted treatments for more than 14,000 patients.

New business opportunities. RollsRoyce is using industrial IoT to change its role within the supply chain from one of ‘component supplier’ to ‘service provider.’ The company’s TotalCare services provide a ‘power by the hour’ model where customers pay based on engine flying hours. The responsibility for engine reliability and maintenance rests with Rolls-Royce, which analyzes engine data to manage engine maintenance and maximize aircraft availability. So, instead of being a parts supplier to the engine manufacturer, it becomes a service supplier to the airline. This is known as servitization and is an example of disruptive change, where IoT has helped enable a new business model.

In the next few years, all industrial companies will need to consider implementing IoT projects. Organizations that wait any longer run the risk of being disrupted by those that get ahead.

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Laggards will find themselves in a ‘race to the bottom’ on price – a race they will probably lose as competitors feed operational cost savings into lower prices. They will also fall behind in customer service, as businesses begin to expect the kinds of services offered by the disrupters. Laggards may even end up selling things that are now essentially obsolete – for example if they’re selling aero engines, when customers really want ‘power by the hour.’

SIEMENS SHOWCASES NEW AND UPCOMING INDUSTRIAL IOT TECHNOLOGIES A recent visit to Siemens’ Innovation Conference was an opportunity to view the company’s new and upcoming technology. Siemens is not just a company that provides software to improve how manufacturers perform, it is also a manufacturer in its own right, with more than 270 factories worldwide. That is one of the key strengths it possesses - an in-depth knowledge of the challenges facing manufacturers. For customers, that means that solutions are beta-tested by manufacturing divisions within Siemens well before general release.

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SIEMEN’S DIGITAL TWIN Siemens has an excellent story to tell about digitalization. The fleshed-out Digital Twin concept with Product, Production and Performance Twins (matched by Design, Build and Operate Infrastructure Digital Twins) is a neat way to bring together Siemens' traditional strengths in design and production control alongside the newer 'Industry 4.0' technologies.

Digital Twin is one of Siemens' key technologies.

Like MindSphere, it is already used - indeed some of the underlying technologies, like product simulation, are well-established. But the packaging up into the virtual product, linked to the real world by MindSphere, is still a relatively new concept. The digital twin is a digital representation of a physical asset. Siemens defines three different types: Digital product twin - for design and simulation; Digital production twin - for process simulation; and Digital performance twin - for continuous simulation during the lifetime of the product in its current configuration.

Knowledge from the engineering models is used to improve the accuracy of the digital performance twin - rather than requiring the system to learn everything from scratch.

Generative design modules can learn from the performance twin, enabling an optimized product design for how the product is used in practice. In this way, engineers can increase design quality.

The digital performance twin runs an online simulation during operation of the product. The simulation is fed by real data from the device, enabling the digital twin to predict potential issues. For example, it can help an operator identify why a motor is problematic or predict the lifetime of a product. This continuous simulation helps to verify design decisions or improve future designs.

risk and reduce overhead. One customer represented at the conference stated that it has more than 500 different enterprise systems operating in 23 countries. Another stated it has over 40,000 customizations in its ERP system. Both companies indicated that they are well into migrating to the new cloud environment.

A presentation by Mark Hurd, Oracle’s CEO, stressed the importance of cloud-based systems for manufacturers and their suppliers, which will alleviate the necessity for multiple data centers to support the disparate enterprise systems. In fact, he predicted that by 2025, the number of corporate-owned data centers will have decreased by 80% and only 20% of the IT budget will be spent on maintenance (compared to 80% today).

In effect, this shifts a lot of the risk, such as installing and verifying updates and insuring intra-system integrity, to the provider.

SOLVING THE SECURITY QUESTION The vendors selling IoT-enabled products or services will need to address the security question. Security should be designed-in at every level, from microprocessor manufacturers such as ARM and Intel to the IoT platform providers like GE Digital, IBM, Microsoft, Oracle and AWS. Manufacturing can get the most leverage from the industrial IoT because of the sheer amount of data it can capture and process.

As data are the underpinning of the industrial IoT, they can be analyzed and visualized to help optimize operations and costs. However, security solutions provided by intelligent sensors, distributed control and complex, secure software are the glue for this new revolution.

Putting systems up in the cloud has significant security implications. It will have to be a combination of software as well as embedded hardware to protect critical control systems from a variety of attacks. Three key challenges are: hardware authentication with secure keys, secure communications using TLS, and secure boot. Since connectivity (the thing that enables the industrial IoT) completely exposes security shortcomings, security cannot be an afterthought if companies are to realize the true benefits of the industrial IoT. In the next two years, Cambashi expects that the plethora of industrial IoT products and services will have consolidated and the pricing models will be simpler and well established. Customers will expect their suppliers to be tracking their products through sensors, as standard solutions replace special IoT projects. Beyond this timeframe, we expect supply chains to be transformed by the digital projects of their participants. That means greater transparency and traceability, with improved customer experience and lower costs.

“Vendors selling IoT-enabled products or services will need to address the security question. Security should be designed-in at every level.”

ORACLE’S MODERN SUPPLY CHAIN EXPERIENCE A recent conference hosted by Oracle underscored improvements in databases and management software to support the supply chain, with many companies actively migrating hundreds of varying business systems to the cloud to enhance productivity, secure

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REFERENCES Cambashi Limited www.cambashi.com

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