Greater Energy Efficiency

---

e

YOUR ELECTRONICS MAGAZINE 

ISSUE 8

Greater Energy Efficiency in Electronics

rswww.com/electronics 08457 201201

You should expect more from a power supply than just power.

Fast Forward with exclusive Agilent functionality

There’s more to a great power supply than just clean, reliable power. That’s why Agilent power supplies are designed to simplify difficult tasks and streamline setups. Backed by decades of power expertise and breakthrough technology, Agilent power supplies provide fast, accurate sourcing and measurements to give you confidence in your results. Agilent DC Power Supplies (200+ choices) Gain insights with scope-like display, ARB and data logger Ensure DUT safety with extensive built-in protections Increase throughput with industry-leading processing speed

Agilent and our Distributor Network Right Instrument. Right Expertise. Delivered Right Now. © 2011 Agilent Technologies, Inc.

www.rs-components.com/agilent

Download our Power Supply Selection Guide Find the one to match your specific need www.agilent.com/find/powerguide

E

s ro controller

er M gy -Efficient

Hello and welcome to the latest edition of eTech from RS Components, bringing you the latest developments and trends in electronic technology, components, design and support products. The increasing pervasion of electronics into almost every aspect of our lives makes for an interesting exponential term within an equation that balances the Earth’s power resources. Not only does it help keep us engineers in our careers, the relentless thirst for technology by industry and consumers alike is also focussing our attention on the efficiency of new and old products alike. It is clear that those products that do the same or more than their competitors with less power input will have an advantage in the market…and consequently an advantage for all of our businesses and bank balances! So, until we successfully manage to harness the power of nuclear fusion, we will remain focussed on making electronic products more efficient. In this issue our main theme is indeed energy efficiency in electronics, discussed in the article on page 6. Amongst other feature articles, we focus on power supply, microcontroller, capacitor and RF technologies, considering their contribution to smarter, more efficient products of the future.

Published by: RS Components Limited. Registered office: Birchington Road, Weldon, Corby, Northamptonshire NN17 9RS. Registered No. 1002091. RS Components Ltd 2011. RS are trademarks of RS Components Limited. An Electrocomponents Company.

Place FSC logo here

I hope you enjoy this issue of eTech!

INSIDE eTech 04 05 06

iSay RS Newsline

Greater Energy Efficiency in Electronics

10 12

Product News

Designing with Energy-Efficient Microcontrollers

16

The Battle has begun between flash & fram

19

Continuous Evolution of electrolytic capacitors for smart society

22

algorithm-based decision making for autonomous automobiles

24

New zero power rf technologies

Glenn Jarrett Head of Electronics Marketing

for Tablet

26 30

Design tips : solar charger

open source : energy-efficient & renewable technologies

34 36 40 42

ELE_0033_1011

A FLASH v FR

ic

E 12 n

Terms and conditions: Terms and conditions of sale set out in the current RS Catalogue. This issue is valid from October 2011 to December 2011.

6

M

ff ic ien cy

gy r Greater Ene

1

06

electronics extra robots to the rescue DesignSpark.com storing green electricity as natural gas eTech - ISSUE 8

03

iSAY Harry Moore Managing Director PULS UK says:

Efficient power supplies

make economic & environmental sense

Using high quality energy efficient power supplies doesn’t just make environmental sense; it makes economic sense as well. Let’s face it, the cost of energy is unlikely to go down anytime in the near future, so why when designing a system to last many years do we not take this into consideration? Most engineers are aware that much of the rhetoric coming from politicians does not in any way represent joined up thinking, with the emphasis being on generating renewable energy rather than reducing consumption through better design. To put this into context, let’s assume energy costs are 10p per Kwh and we are operating a control system using a 1000W (1Kw) power supply. If this power supply is only 80% efficient this would mean a wastage of 250W, whereas a top quality unit delivering 96% efficiency would only lose 52W, equating to a £174 a year saving and a corresponding reduction in CO2 emissions. It would only therefore take 10 units to make a total saving of £1740 over one year! Other savings can be made if the unit no longer has a high inrush current. If the unit only takes 5 amps at start up (instead of anything from 30-60 amps) then the wiring used can be thinner. In addition, if the system is mission critical then the UPS system can be smaller. Our chief design engineer is famous for sending new designers back to start again if they have used any small capacitors. He believes that in the context of power supplies, small capacitors are the first point of failure with any unit and if they are in the control circuitry you will not find this out until something bad happens. How many systems out there no longer have overvoltage or reverse voltage protection and their operators are not aware of it? OK so let us assume you have designed your mission critical system, used an N+1 array of power supplies, chosen them carefully, used diode protection on the outputs only to single fuse all the inputs to the power supplies. It amazes us here at PULS how often there is a single point where failure could bring down the whole system. Size and efficiency are interdependent. Designers of some of the cheaper power supplies try to compensate for low efficiency by adding large heat sinks; but really this is just inefficient bad design.

04

eTech - ISSUE 8

...a top quality unit delivering 96% efficiency would only lose 52W, equating to a £174 a year saving and a corresponding reduction in CO2 emissions. PULS power supplies are built with the customer in mind, with a huge range of products available including AC/DC single and three-phase power supplies, DC-DC converters, DC-UPS, buffer modules, MOSFET and redundancy systems. All provide outstanding efficiencies and feature super compact, lightweight housing to meet the needs of the most demanding systems. Products extend from 5V to 72V outputs with power ratings from 15W to 960W, with extensive approvals available on many units including ATEX, GL, CE, CSA and many more.

To see the full PULS range visit rswww.com and search for ‘PULS’

What do you think? Share your opinion on the economics of using energy efficient power supplies at www.designspark.com/etech

RS NEWSLINE

Introducing a new series of free schematic symbols and PCB footprints RS Components and Accelerated Designs introduce component libraries for STMicroelectronics and Microchip, as the first in the range to be released. The new series of component libraries provide customers with schematic symbols and Printed Circuit Board (PCB) footprints for an extensive range of products from STMicroelectronics and Microchip.

RS Components supports the relocation of elephants in Sri Lanka During the dry season in Sri Lanka, elephants wander the local rice fields at night destroying all the crops; this has significant repercussions on the livelihood of the local people. Professor Nobert Bartos and his team at the polytechnical university in Vienna offered to help. A solution of using a fence system that rang an alarm when elephants entered the rice fields was developed. Engineers created a neuronal network that identified the language of the elephants that was able to send signals to tell the elephants to stay away from the fields. This system consists of a microphone, various amplifiers, a microcontroller and various other electronics parts. All of the components for the two prototypes were sponsored by RS Components Austria.

Thousands of PCB footprints and schematic symbols are available for free download in a vendor-neutral format from RS’ online DesignSpark electronics design community and resource centre, and can be exported to virtually any EDA and CAD/CAE system using Accelerated Designs’ Ultra librarian (UL) translator software, thus saving the design engineer valuable time and effort in the CAD design process. The UL Reader also supports RS’ free DesignSpark PCB design tool that offers powerful schematic capture and PCB layout software. The free Ultra librarian soft ware, including footprints and symbols, is available now for download at: www.designspark.com. Bill of Materials (BOM) reports can be generated and prices quoted using RS’ free Online Quotes tool.

RS Components, Elektor and Circuit Cellar announce new Design Challenge Competition The competition in partnership with Microchip is focused on energy (TBC) and will be launched officially in November at Elektor Live. Utilising the new Digilent ChipKIT3 MAX32 based on a Microchip PIC32 core, the Design Challenge will offer Engineers the chance to acquire 1 of 1000 free boards we are giving away, to develop an innovative shield using DesignSpark PCB, RS Component’s free award winning PCB design software.

boards can be easily realised. The challenge will be to develop the most innovative and novel solutions in an specified area (TBC). The Competition will conclude in March 2012, where the winners will be announced at Circuit Cellar Live.

The MAX32 board offers an open source solution where add-on ‘shield’ or expansion

For more information go to www.designspark.com eTech - ISSUE 8

05

y g r e n E r e t a e Gr y c n e i c Effi nics in Electro

06

eTech - ISSUE 8

According to publicly available statistics from the International Energy Agency (IEA), the intergovernmental organisation, the world’s total consumption of fuel in 2008 was estimated at more than 8400 Mtoe (Million tonnes of oil equivalent), up from approximately 4670 Mtoe, almost doubling over a 35-year period. And gross energy production increased by 10% over a four-year period (2004 to 2008) with a corresponding increase in annual CO2 emissions, while the world’s population only increased by around 5%. Additionally, worldwide energy consumption is predicted to increase, on average, by 2% per year up to 2030. This level of increase will lead to annual energy consumption doubling every 35 years. According to some recently available statistics, energy consumption actually climbed by 5.5% in 2010, but this followed a 1% decrease in 2009, a blip, or a glitch perhaps, in the overall trend caused by the recent global financial and economic crisis. Although widely known international efforts are being made to decarbonise the electricity sector and reduce the dependence on fossil fuels, with a combination of renewable energy technologies, nuclear power and fossil fuels, combined with CCS (Carbon Capture and Storage), no one seems to be predicting that global demand for power is going to slow down anytime soon. In fact, all the evidence says that we want still more personal smart gadget type things to tell us exactly where we are and how we really ought to be somewhere else five minutes ago; in addition to more prosaic concerns, such as having warm homes. It should be abundantly clear why energy efficiency is becoming an increasingly important factor in our lives, even if there remain levels of scepticism in our societies about climate change, global warming, CO2 emissions, et al. Dwindling energy resources – or at least those easily available at relatively low cost, energy dependence on foreign countries, and sharply increased fuel costs overall, should be more than enough to concentrate anyone’s mind on the issue. So what is energy efficiency? To quote the intergovernmental organisation, the IEA: ‘Something is more energy efficient if it delivers more services for the same energy input, or the same services for less energy input.’ Well, that sounds easy, like playing a musical instrument, as explained by J.S. Bach: “All you have to do is touch the right key at the right time and the instrument will play itself.” Of course we know implicitly that things are never so simple. New technologies are certainly making significant ground in finding

better use of already available energy through improved efficiency, such as better insulation or replacing all the incandescent lighting in our homes with CFL (Compact Florescent Light) bulbs, which use less energy to produce roughly the same amount of light. But the real challenge, especially given tight cost constraints and ever increasing demands to deliver cutting-edge performance, is for engineers who are designing and developing the nextgeneration electronic products and systems in a myriad of diverse fields, such as mobile consumer devices, PCs, communications, lighting, industrial automation, home entertainment, automotive and medical electronics, among many others. The pervasiveness, if not ubiquity, of electronic devices is becoming an increasingly significant contribution to global power consumption. So, it is becoming more and more crucial that power management moves up the list of design priorities, at least taking its place at the top table with those other famous design ‘P’s - Performance and Price if not even becoming the most critical factor.

...home entertainment, for example, such as HDTVs and set-top boxes, power consumption is also playing a major role, especially so when the box is in standby mode, which is potentially the majority of the product’s lifetime. Accordingly, the vast majority of global electronic product makers have realised the importance of low power design for sometime now, and for any number of reasons, not least of which is national governmental and international energy-efficiency regulations. New legislation is continually evolving and being passed, demanding ever greater power efficiency, such as the US Environmental Protection Agency’s (EPA) Energy Efficiency Level V, which specifies for not only full loads, but also the no-load condition or standby mode of electronic products. Additionally, consumer demand is clearly growing for low power consumption or ‘energy light’ products – most patently in the mobile gadget sector where battery longevity is a major factor; and also a highly significant feature for manufacturers to push to

Continued page 08 >

eTech - ISSUE 8

07

< Continued from page 07 their customers. And in home entertainment, for example, such as HDTVs and set-top boxes, power consumption is also playing a major role, especially so when the box is in standby mode, which is potentially the majority of the product’s lifetime. Box makers are now looking to chip and system makers to provide exceptionally low standby power consumption figures and then deliver leading-edge performance to ‘wake-up’ the product in a timely manner, ready for viewer operation. In semiconductor chips – the devices that lay at the heart of any modern electronic product – manufacturing process-technology geometries are continually shrinking, in line with the famous Moore’s Law. Roughly, this law states: the number of transistors that can be placed cost-effectively on a given area of silicon will double every two years. This process, driven by demands for lower power consumption, lower cost and higher reliability in modern electronics goods, has enabled the increased integration of logic and control functionality into ‘single-chip solutions’, enabling engineers to use perhaps just one central controlling or processing chip in their design, where previously they had no other option than to use a number of discrete chips. Today, the latest cutting-edge complex Systemon-Chip ICs, ASICs (Application-Specific ICs) and microprocessors now integrate hundreds of millions of transistors with feature sizes as small as 32nm (or 32 billionths of a meter) and below. However, this level of integration can bring a whole host of chip design issues because of the significant increase in leakage power from the eversmaller transistors. This has led to chip designers needing to use every technique they know to manage power consumption, which fundamentally are based around the central tenet of turning off those elements of the chip that are not absolutely necessary to overall chip functionalityat any specific operating point in time. System partitioning for highly complex chips

08

eTech - ISSUE 8

is one weapon in the designer’s armoury to reduce power, making the trade-offs between performance, cost and power consumption. Depending on the constraints of the end application or product, this could be implementing frequently used computational processes in hardware to deliver the required overall performance, while choosing other processes to be run in software, potentially saving silicon die area. Other more advanced techniques to reduce on-chip power could include supplying the minimum voltage or changing the operating frequency in certain areas of logic circuitry, but bringing the penalty of significantly extra complexity into the design. At the system or board level similar choices, working again with the trade-offs on price, performance and power, will also need to be made. For example, selecting system-level devices such as ASICs or ASSPs (ApplicationSpecific Standard Products) or deciding to use general-purpose ICs such as MCUs (microcontrollers) or DSPs (Digital Signal Processors), or possibly even FPGAs (Field Programmable Gate Arrays). To reduce overall power consumption, it’s increasingly clear that designers will need to take the holistic approach for low-power system design, selecting the right components to do the job, obviously within the required performance and cost constraints.

RS Components works closely with manufacturers from across the industry to stock energy efficient technologies that save power in new designs. See the latest introductions at rswww.com/electronics

Share your views... developments that can further reduce energy requirements in new designs at www.designspark.com/etech

Where innovative products are just the beginning. Molex is known for technical innovation. In the last five years, we have secured 2,000 patents and contributed to numerous global standards. From highspeed to sealed solutions, to microminiature and power interconnects, the expertise gained in the development of our broad range of products gives us

www.rs-components.com/molex

a unique advantage in the pursuit of future solutions. But Molex innovation goes far beyond products. Our efficient “one company” approach gives you seamless service, support and distribution, anywhere in the world.

This drive to find new ways to meet customers’ challenges is what Molex is all about.

PRODUCT NEWS Texas Instruments Evaluation Board MSP-EXP430FR5739 Experimeter Board

TE Connectivity 1.5mm AMP Mini CT Connector Series

n The MSP-EXP430FR5739 Experimenter Board is a development platform for the MSP430FR57xx devices, supporting the new generation of MSP430 microcontroller devices with integrated Ferroelectric Random Access Memory (FRAM). RS Web search term: 740-1116

Miniature wire-to-board and wire-to-wire connectors n Similiar to the standard AMP CT connector series, these connectors are tailored for improved harness productivity and feature a compact design with contacts on 1.5 mm pitch. Wire-side connectors can be used to produce a variety of harness styles by fully automatic high-speed assembling machines. RS Web search term: mini-CT

Harwin M20 2.54mm Pitch Connector

DRV8412 Motor Driver Evaluation kit Includes a C2000 Piccolo F28035 MCU control card. n With its highly integrated and robust motor control and driver it will speed the development time for brushed and stepper motors. RS Web search term: 739-8048

n A comprehensive range of 2.54mm pitch connectors for board-to-board and cable-toboard applications, with twin-leaf phosphor bronze contacts. RS Web search term: Harwin M20

Bourns Transient Blocking Unit (TBU) High-Speed electronic current limiter protection n The TBU device provides blocking protection for both power cross and lightning. Benefits of the TBU device includes overvoltage and overcurrent protection in one, offering high speed performance and precise output current with high bandwidth. RS Web search term: Bourns TBU

10

eTech - ISSUE 8

See more online - Over 5,000 new products are

product NEWS

iWatt, AC-DC controller Digital PWM Current-Mode Controller for Quasi-Resonant Operation. n iWatt’s AC-DC controllers are the first in the industry to bring cost-effective digital control techniques to AC-DC power conversion.Digital PWM Current-Mode Controller for Quasi-Resonant Operation. Reduces number of components and cost. RS Web search term: 739-8152

EAO Series 51 Stop Switch Features a monoblock design with a built-in contact block, to set a mounting depth of less than 19mm n The Series 51 is a universal stop switch which can be adapted to almost any type of application, but is particularly suitable for handheld remote controls, narrow control panels and newer electronic applications where behind-panel space is restricted. Compatible with operating voltages from 10μA/100μV up to 250V/5A, and there is a choice of connections including solder/plug-in, solder, or universal (Plug-in, Solder, PCB). RS Web search term: 737-7041

Freescale, K60 Kinetis Tower System Kit Evaluation boards, tools and runtime software n The TWR-K60N512-KIT is part of the Freescale Tower System, a modular, reusable development platform. RS Web search term: 726-9146

Atmel, Q Matrix Touch Sensor ADEUNIS RF, ARF50 I/O Module Wireless Digital & Analog I/Os Modules n The ARF50 is an I/O module that can acquire digital or analogue states from sensors, dry contacts or counters, in order to control remote equipment. RS Web search term: 736-9233

added at rswww.com/electronics every month

QProx™ QT60248 n “24 KEY QMATRIX™ IC, individually adjustable for sensitivity, response time, and many other critical parameters.” RS Web search term: 696-3190

eTech - ISSUE 8

11

Designing with

Energy-Efficient Microcontrollers Dr William Marshall, RS Components

The increased use of embedded microcontrollers in electronic equipment coupled with a world energy crisis will force electronics engineers to look at hitherto ignored power-saving features of these devices.

12

eTech - ISSUE 8

Historical perspective Back in 1976 a new computer was launched: the Cray 1. At the time it earned the title ‘Supercomputer’ because of its incredible processing power of 160MIPs at a clock rate of 80MHz. Computing power wasn’t its only recordbreaking feature: the Cray 1 required a 115kW power supply and was packaged in a case not much bigger than a UK telephone box. To stop it melting, a powerful Freon-based refrigeration plant was incorporated in the structure. For comparison with technology available today, consider the Parallax Propeller microcontroller; it’s a 32-bit bus machine compared to the Cray’s 64 but it too manages 160MIPs with an 80MHz clock. The significant difference (apart from physical size) is in the power required to achieve that performance. The Propeller has an average power consumption of just 1 watt and many newer devices can do a lot better than that. The 64-bit dual-core Intel Atom-based PC I’m typing this on consumes so little power that the current-sensing mains socket expander it’s plugged into fails to notice it’s been switched on….. The coming of VLSI led inevitably to computers with a much better processing power to supply power ratio. Early NMOS chip technology gave way to CMOS which promised even lower demands on the power supply. A characteristic of CMOS is that significant current is only drawn when a logic device changes state. This means that the faster it is clocked the higher the average current consumption for a given microcontroller. So a particular MCU will have two contributions to the power budget: static and dynamic. Static voltage reduction Energy is consumed by the device through leakage even if the clock is turned off. In newer devices individual circuit elements are being packed closer together reducing insulation resistance and requiring a drop in the supply voltage. Logic able to operate at +1.8V is quite common now, with some working with a supply as low as +0.9V. For example the Microchip nanoWatt XLP range of PIC microcontrollers can operate over the voltage range +2.5 to +5.5V up to a maximum clock frequency of 32MHz. If you can make do with 16MHz, then the supply can be dropped to +1.8V providing peripheral devices will also work with this low voltage. This produces a drop in both the voltage and the frequency dependent power consumption. Static frequency reduction If no special power saving modes are available then always consider using the lowest clock speed possible compatible with getting the task completed in the time available. For something as simple as a TV remote control for example, a ‘watch’ crystal frequency of 32kHz is often used.

Dynamic voltage scaling In more complex situations, these fixed or static solutions may be unsuitable because the processing load may vary and high-speed operation is maintained ‘just in case’. In these situations a technique called Dynamic Voltage Scaling (DVS) may be used where software analyses the processor demand and causes the clock speed and supply voltage to be varied accordingly. However the savings calculations are complex and many factors such as memory usage must be considered. Dozing and Sleeping Early micros had no special operating modes to save power: probably because their processing power was so low that applications allowing the processor to ‘doze off’ were deemed unlikely! The invention of the battery-portable digital instrument changed all that. Mobile phone design requirements have since driven development in both energyefficient MCUs and battery technology. One of the first MCUs to feature an Idle mode was the Intel 80C51. New devices have introduced a whole menu of power saving modes most of which consist of shutting down functions when they are not needed. Most microcontrollers are now used in ‘real-time’ control situations requiring bursts of activity followed by perhaps complete inactivity for long periods. The TV remote control is an extreme case where the processor can be completely shut down until a button is pressed. The average current consumption can be little more than the selfdischarge rate of the battery. Increasingly, real-time systems are moving away from the single central processor model to a central high-level controller fed part-processed data from ‘intelligent’ sensors. The MCU attached to each sensor device will be probably taking analogue samples at fixed intervals, performing some DSP operations and then transmitting the result on a serial bus. In this case the sensor MCU is ‘woken up’ by a timer at each sampling interval. Now things get interesting: should you select a simple 8-bit microcontroller or fast 32-bit type, say based on a Cortex M0 core? Logically, the 8-bit MCU seems more efficient because it’s cheap and will be fully committed for most of the available processing time. In fact, the 32-bit device might be better in terms of average current consumption because it can complete the task quickly and then go to sleep (Fig.1).

Continued page 14> eTech - ISSUE 8

13

< Continued from page 13 Even this technique has to be used with caution: there will be an optimal clock speed and not necessarily the maximum. In other words completing the task in the shortest possible time with the fastest clock won’t always yield the lowest average current consumption. Fortunately much of the speed improvement over the old 8-bit device will be down to a more powerful instruction set featuring single-cycle 32-bit multiplication for example. But don’t despair if an old 8051-based design needs to be improved while retaining software compatibility: the 8051 core has seen dramatic improvements in execution efficiency (fewer clock cycles per instruction) as well as big increases in overall clock speed. The Silicon Laboratories range for example, provides single-cycle instructions at up to 100MIPs. When using the sleep modes an important consideration is the Wake-up time. Oscillators can take milliseconds to produce a stable output and this represents wasted time and power. With short duty-cycles the MCU might have barely woken-up before the next wake-up call arrives! The Microchip nanoWatt™ MCUs feature a ‘Doze’ mode which allows the processor clock to run more slowly than the peripheral clocks. This works in situations where the peripheral device must work at full speed, but the processor doesn’t have a lot to do while waiting for a peripheral interrupt. Cutting power supply wastage You’ve designed your microcontroller system for lower power consumption, but what about the power supply itself? If you’re an old-hand you might just go for a trusty 78xx series linear regulator, but these are now considered completely obsolete if still popular. Although more expensive, always go for a newer low dropout (LDO) type.

Full clock speed Supply Current Idle/Sleep

Average Supply Current

eTech - ISSUE 8

Time

8/16-bit Processor

Time

Supply Current

Average Supply Current

Figure 1. A more powerful MCU consumes less dynamic current.

A 7805 +5 volt output regulator has a dropout voltage of 2 volts which means that it needs a minimum of +7 volts on the input. At the maximum current of 1 amp at least 2 watts are wasted as heat and a heat sink will almost certainly be needed. An LDO type cuts the dropout to perhaps 300mV. Now that means a lower voltage mains transformer can be used cutting the waste. Better still, use a switching regulator for even greater efficiency. However, remember that the PSU must be rated for the peak current consumption – not the average.

References [1] Power Management and Dynamic Voltage Scaling: Myths and FactsDavid Snowdon, Sergio Ruocco and Gernot Heiser http://ertos.nicta.com.au/publications/papers/Snowdon_ RH_05.pdf

Finally, include pull-ups on all unused I/O inputs. Random noise on a floating input can switch internal circuits and even if the resulting signals are blocked and cause no spurious operation, it all adds to the total dynamic current. Some devices feature internal ‘weak pull-ups’, but opinion seems to be divided on their efficacy and many developers stick to using external resistors.

[5] Silicon Labs Pipelined 8051 Microcontrollers www.silabs.com/Marcom%20Documents/Resources/ MCU_Catalog.pdf

Conclusion Energy costs are top of everyone’s agenda at the moment and as electronic equipment continues to proliferate in the domestic market, design engineers must assume that power consumption will be a critical factor in their projects. Fortunately the need for lowpower devices in battery portable equipment started the process of energy-efficient chip design some years ago. Now this new chip technology combined with energy saving software will help reduce wastage in mains-powered equipment as well.

14

Fast 32-bit Processor

[2] EFM32 Introduction White Paper http://cdn.energymicro.com/dl/pdf/efm32_introduction_ white_paper.pdf [3] The New ARM Cortex-M0 Processor http://ics.nxp.com/support/documents/microcontrollers/pdf/ arm.cortex-m0.iq.pdf [4] Practical Applications of Low-Power Design with nanoWatt XLP™ ww1.microchip.com/downloads/en/DeviceDoc/Future%20 XLP%20Article.pdf

[6] PIC Microcontroller Low Power Tips ‘n Tricks ww1.microchip.com/downloads/en/DeviceDoc/01146B chapter%202.pdf

FIND IT: go to rswww.com/microcontrollers to see the full range of micros available on RS, and use our advance comparison search to find the right device for your application.

Share your views...

What do you think are the best performing microcontrollers for managing power consumption? Tell us your views at www.designspark.com/etech

NEW! RECOM’s most efficient and compact 1A switching regulator Introducing the next generation of the popular R-78. Over 5 million sold!

Very high efficiency - up to 96% Ultra wide input range - 5 to 42Vin (>8:1) Low profile case- 11.6x10.4x8.5mm 1Amp continuous output current Low standby current (1mA) -40°C to + 85°C Operating Temp. 3-year warranty SIP3 package compatible to TO-220 footprint

fig. actual size

RECOM, the inventor of the R-78 switching regulator replacement for linear regulators, releases the next generation. The R-78C series. The existing features of the standard. R-78 series (high efficiency, small case size & pincompatibility with 78-series linear regulators) have been improved by adding a much higher input voltage range of up to 42VDC and double the output power in the same size case. This means that the R-78C series can offer 15W of power in a case volume of only 1cm³. The ambient operating temperature covers the full industrial range of -40°C to +85°C, conversion efficiency is up to 96% making heat-sinking unnecessary and the output is fully protected against overloads and short-circuits.

Increased input voltage range: 5 to 42VDC!

Applications for the R-78C include industrial controls, batterypowered devices, hand-held equipment, avionics, fancontrollers and embedded designs, but this versatile switching regulator module will find uses in every branch of electronics.

The Battle has begun between

FLASH & FRAM New embedded systems and applications are continually demanding the development of highly robust microcontrollers (MCUs) that deliver higher performance and lower power consumption. A key element of this drive is the development and integration of new embedded non-volatile memory technology. Currently, the dominant non-volatile memories used in microcontrollers are Flash and EEPROM, but there are a growing number of alternative technologies that offer the same basic functionality. An Introduction to FRAM One of these competing memory technologies is Ferroelectric Random Access Memory, or FRAM (other widely used acronyms include F-RAM or FeRAM). As the ‘RAM’ part of the name already suggests, FRAM behaves similarly to DRAM – it allows random access to each individual bit for both read and write operations. Unlike DRAM, FRAM is a non-volatile memory like EEPROM or Flash memory – so it does

16

eTech - ISSUE 8

not lose its content when power is removed. FRAM is also similar to DRAM, operationally, but has a cell capacitor that uses a ferroelectric material, typically lead zirconate titanate (PZT), to deliver its non-volatile properties. Very basically, an electrical field can be applied to polarize the material by moving the Zirconium atom in the PZT crystal structure and forcing it into an up or down orientation, therefore storing a ‘1’ or ‘0’ data bit. Note that the term ‘ferroelectric’ does not mean that FRAM contains iron (Fe), nor does it imply that the memory can be influenced by magnetic fields. Key Advantages FRAM has several key advantages over Flash or EEPROM technologies including speed, significantly higher write-

erase cycle lifetime, and lower power consumption, primarily due to its much lower programming voltage. Additionally, FRAM does not require a special programming sequence to write data. In terms of speed, the actual write time to an FRAM memory cell is less than 50ns, approximately 1000 times faster than EEPROM or 100 times faster than Flash. Additionally, unlike EEPROM where two steps are required to write data – a write command, followed by a read/ verify command – FRAM’s write memory function happens in the same process as read memory. So, there is only one memory access command, one step for either reading or writing. Then there’s low power consumption. Writing to the FRAM cell occurs at low voltage (around 1.5V) and very

little current is required to change the data, whereas significantly higher voltages (10 to 14V) are required for EEPROM and Flash. FRAM’s low voltage translates into low power usage and enables more functionality at faster transactions speeds. And reliability? Because only a small amount of energy is required, all the necessary power for FRAM is ‘front-loaded’ at the beginning of data writing. This avoids ‘data-tearing’, which is a partial write of the data that can occur, for example, when EEPROM-based smart ICs are removed from the RF field power source during a write cycle. Additionally, FRAM delivers more than 100 trillion (1014) read/write cycles – far exceeding those of Flash and EEPROM. FRAM is also uniquely flexible as it offers the ability to use the same unified block to function as memory for both program code and data. Designers can dynamically partition the memory depending on the current stage of the user’s development cycle. This feature allows faster time-to-market and simplified inventory control – one single device can be dynamically configured into various memory configurations. The technology also offers additional security and robustness compared to Flash and EEPROM. As FRAM is crystal-based, rather than charge-based, its terrestrial Soft Error

Rate (SER) is below detection limits and is not susceptible to radiation. Additionally its ultralow power requirements and high speed make FRAM data read/writes virtually undetectable to unauthorized ‘sniffing’ or ‘data profiling’. New Microcontrollers with Embedded FRAM One semiconductor manufacturer in particular, Texas Instruments, is seeking to advance this technology in embedded applications with the integration of FRAM memory into its MSP430 family of ultra-low-power 16-bit microcontrollers. The new MSP430 devices with embedded FRAM are cutting the industry’s best active power consumption by half, achieving sub100μA/MHz. Read and write requires just 1.5V, so it is able to operate without a charge pump, unlike Flash and EEPROM. This lowers power consumption and minimizes physical footprint. In a typical application test case (8MHz CPU speed with both memory options capped at 12kB/s throughput), FRAM consumes 9μA, whereas Flash consumes 2200μA, a factor of more than 250 times less power. In addition to lower power performance, FRAM can also maintain unmatched data throughput. The MSP430 is capable of 50ns access times, enabling speeds of up to 1400kB/s. Embedded memory is no longer the system bottleneck,

as FRAM can write more than 100 times faster than flash, while consuming less power. In a typical application test case (8MHz CPU speed with both memory options writing 512B memory blocks), FRAM maximum throughput is 1400kB/s at 730μA, with Flash maximum throughput at 12kB/s at 2200μA. FRAM’s virtually unlimited write endurance of 1014 cycles offers longevity and endurance that existing memory technologies cannot match. Again, in a typical application test case (8MHz CPU speed with both memory options capped at 12kB/s throughput), FRAM will last for 6.6x1010 seconds, while Flash memory will last for 6.6 minutes, so around one billions times longer than Flash. This increased write endurance is particularly ideal for data logging, digital rights management (DRM), batterybacked SRAM and many other applications.

Find new Flash and FRAM devices at rswww.com/semiconductors

Share your views... Tell us your thoughts on the battle between Flash and FRAM at www.designspark.com/etech eTech - ISSUE 8

17

Radiall TestPro cable assemblies Best in class for vSwR and for insertion loss/phase stability

Test and measurement cables Test cable assemblies are intended for daily use in components and assembly shops, test labs and automatic test equipment applications. They differ from standard cable assemblies in the fact that they are especially designed for applications that require repeated connection/disconnection procedures, strenuous flexing situations and applications where cable and connector wear becomes an issue.

www.rs-components.com

Radiall TestPro test bench cables Radiall TestPro phase stable cables are test bench measurement cables. They combine electrical advantages and integrated protection system. These rugged assemblies offer excellent durability while remaining exceptionally flexible. Unique connector attachment system and strong cable structure provide high tensile stress resistance to the whole assembly. Radiall TestPro 4.2 offers the best cost per measurement. TestPro 4.2 test bench cables have superior electrical stability, higher resistance to torque and flexure stress than standard lab cable assemblies. They are dedicated to lab and production test.

Continuous evolution of electrolytic capacitors contributes to cutting emissions High-efficiency power-conversion technologies are becoming increasingly important in the drive towards a low carbon economy. Intensive developments are taking place in next-generation semiconductor devices, based on materials such as SiC (silicon carbide), for use in power inverters and converters. In addition to this, work is ongoing in improving other indispensable electrical components such as aluminum electrolytic capacitors – making them smaller with higher withstand tolerances and greater reliability. Continued page 20 > eTech - ISSUE 8

19

< Continued from page 19 Low-emission future? Ignoring political or socioeconomic issues for a moment, in terms of the production, transmission and localised use of electrical energy, there are three principal ways to realise a low-carbon-emission and smart-energy-based society: 1. The creation of electricity via low-carbon-emission energy sources such as solar and wind power. 2. Moving away from petroleum-based engines to the use of alternative energy sources, such as those used in EV/HEV (Electric Vehicles/ Hybrid Electric Vehicles) applications. 3. The improvement in the operating efficiency of existing electrical devices. Motors consume majority of power There are conversion technologies for connecting energy-generating devices to commercial power lines, such as power conditioners and grid-connection devices. And there are next-generation regenerativebraking, motor- and battery-control technologies being designed for use in EV/HEVs. However, to improve the efficiency of common electrical and electronic devices, it is important to take a closer look at the devices that consume the majority of the power. People might imagine that electrical power is fully converted to light energy for lighting, heat energy for heaters, kinetic energy for motors and actuators. In reality, of course, not all the applied energy is converted into its intended type. In fact, much of it becomes unnecessary heat energy that warms the planet. In this sense, computers and other IT devices are nothing more than generators of heat. Of all components, it is motors that consume the most power. Clearly, motors are used in an exceptionally wide range of devices including industrial equipment and household goods such as washing machines and vacuum cleaners, in addition to compressors of air-conditioners and freezers. The number of motors being used today is

20

eTech - ISSUE 8

staggering and the worldwide motor market is estimated to be more than six billion units per year. Data is also available that, for example, indicates motors actually account for approximately 50% of the total energy consumed in Japan*. So, enhancing motor efficiency is an important objective in improving electrical efficiency overall. Inverters and converters To realise the low-carbon-emission and smart-energy society, we will need to develop new power conditioners and gridconnection systems, new drive and regenerative-energy technologies in automotive applications, better battery control for a range of devices, and certainly the improvement of motor efficiency. Although these may appear to be completely unrelated, a common factor becomes apparent upon taking a closer look: All of these involve the conversion of power from AC to DC, DC to DC, or DC to AC. So, one can make a case that the development of inverter and converter technologies will ultimately determine our success or failure in developing the low-emission smart-energy society. Motors require some further explanation: The rotation speed of induction motors, used primarily in industrial devices, is determined by the power supply frequency. For this reason, dampers and valves are installed to adjust the pumping or wind flow rates delivered by motors. However, electrical power is proportional to the cube of the rotation speed of motors. And as the efficiency of motors can be drastically improved if the speed is changed using an inverter (for variable frequency), manufacturers are increasingly adopting the use of inverters in motors. Electrolytic capacitors Inverters and converters for converting electrical power are relatively high powered and can handle large voltages and currents. At the core of these devices are a power semiconductor (as the switch), a large inductor, and a large capacitor. Although the development of low-loss and hightolerance devices based on SiC is becoming increasingly important in the field of semiconductors, there is also ongoing development of new technologies for inductors and capacitors – and aluminum electrolytic capacitors are not exempt. Engineering requirements demanded for aluminum electrolytic capacitors used in inverters and converters are: smaller size,

high withstand characteristics, high ripple current compatibility, improved charge/discharge tolerances, and increased resistance to environmental factors such as temperature and vibration. Size and withstand characteristics The most highly demanded features are smaller size and higher withstand capabilities. These devices, when used in inverter or converter, take up the majority of the surface area, and higher withstand voltages are necessary for photovoltaic power generation conditioners. Although smaller sizes can be achieved while maintaining the same capacity, by basically making the dielectrics thinner, this can be difficult due to the trade-off with the withstand characteristics. To cope with this problem, manufacturers are: increasing the electrical capacitance per unit-surface-area of the electrode using high-powered electrode foils; developing electrolytes with high withstand voltage capability, while maintaining the equivalent resistance of conventional electrolytes; and improving the charge rate by reassessing the overall structure and specific structural components, for example, creating thinner separators while maintaining withstand voltage characteristics. As a result, standard ratings that were previously between 400V and 450V have now expanded to include 500V and 700V.

Size : Ø63 x 150L

Series name :

Ø63 x 115L

63 x 100L

NX NK NC

Ripple : 14.4 Arms

12.8 Arms

16.5 Arms

Advancement in shapes and rated ripple current Example shown: 400V/3900uF (nichicon) product

High ripple current compatibility In addition to the flow of high ripple current in capacitors in inverter and converter circuits, there is also high ripple voltage. Resistance, such as ESR (Equivalent Series Resistance), impacts upon the life of these circuits as the ripple current causes heating of the capacitors. Although the main factors of resistance for aluminum electrolytic capacitors are electrolytes, separators, electrode foils and connectors, many products are being introduced with higher allowable ripple current than conventional products. Efforts in this area include: the development of electrolytes with improved long-term stability; the use of highly stable and high-capacity electrode foils such as electrodes that use amorphous film as the dielectric film; the use of low-density high withstand voltage electrolytic capacitor paper; and the reassessment of thermal discharge structures. In motor-installed devices, there is also major fluctuation in the applied voltage. In this case, malfunction resulting from a short circuit may ultimately occur from a partial drop in withstand voltage, due to local stress on the electrode foils during charge/discharge (especially during discharge). Such risks are avoidable using high-ripple compatible products. Highly vibration-resistant structures for automobiles Inverters installed in automobiles and industrial devices are exposed to harsh environments, including high temperatures and vibration.

Additionally, manufacturers have developed unique technologies to meet demands for expanded temperature ranges and a higher service life for aluminum electrolytic capacitors. As a result, there are products that now guarantee 105°C for conventional use and up to 125 or 150°C for use in automotive. However, installing an inverter in a location exposed to strong vibrations such as in the transmission, or gearbox, of an automobile also means major vibrations for the aluminum electrolytic capacitor. For these applications, there are also technologies that can withstand vibration of up to 20G. Aluminum solid electrolytic capacitors While aluminum electrolytic capacitors are becoming smaller in size and have improved withstand characteristics, ripple, charge-discharge and environmental resistance, there is also advancement in the development of aluminum solid electrolytic capacitors. New devices are now using PEDOT (polyethylenedioxythiophene), instead of electrolytes as a conductive polymer, and offer high withstand capabilities for use in small-to medium-sized converters. Like aluminum electrolytic capacitors, aluminum solid electrolytic capacitors are small in size and have a large capacity. They do however have many advantages including longer service life, small ESR and, due to the solid electrolyte, no concerns about fluid leaks or transpiration. Previously, the application of these capacitors was limited, due to the withstand voltage of conductive polymer which was around 40V. However, aluminum solid electrolytic capacitors also have many features not found in aluminum electrolytic capacitors using electrolyte. This has resulted in an increase of market share in the high-voltage area: for example, in converters used for operating LED backlighting on flatscreen televisions. Capacitor manufacturers are also trying to solve the ferric-ion issues associated with withstand capability, by developing conductive polymers that offer superior withstand characteristics, in addition to optimising the elemental structures of separators and dielectric film. As a result, even 100V products are now being seen in the market. The reliability of these products is also high, guaranteeing 3000 hours of operation in high-temperature environments up to 125°C. * Investigation concerning the present and near-future trends of power consumed by electrical devices. (Fuji-Keizai, March 2009) FIND IT: Compare the full range of electrolytic capacitors available from RS at rswww.com/capacitors

Share your view... Got a view on how electrolytic capacitor technology needs to develop in the future? Share it at www.designspark.com/etech eTech - ISSUE 8

21

Low-Cost Route to Research

Algorithm-based Decision Making for Autonomous Automobiles Whether it’s reading novels or going to see blockbuster Hollywood films, no doubt we’ve enjoyed our helping of science fiction over the years and its many visions of what tomorrow might look like.

It’s a subjective issue, of course, but for many perhaps the really thought provoking ideas are those that offer predictions of technologies in a nearby future. So, if we plead indifference for a moment to Orwellian-style dystopian visions and wildlyout-of-control AI-based computers and consider those predictions of future technologies that have potential for improving our daily lives, today, then one idea that has cropped up repeatedly in sci-fi over the years is the fully autonomous or computerized vehicle. Admittedly, sometimes vehicles in sci-fi futures are driven by androids: but this is essentially the same idea. The belief, presumably, is that people might somehow feel more secure being driven by a computer that looks a bit like them!

22

eTech - ISSUE 8

Automotive Revolution But how close is this idea of a driverless car to reality? What sort of research and development is required and how can it be tested? Certainly, over the last decade, new technologies and ideas have revolutionized the automotive industry. Driver-assistance technologies such as ABS and electronics-based stability control are long established. Image processing and sensor-based advanced driver-assistance safety systems, such as lane-departure warning, pedestrian detection and forward-collision detection are becoming increasingly common, at least in high-end cars. And automatic parking technologies are now more or less out of their infancy and beginning to mature. All of these are just some of the components within the full suite of technologies that will be needed to bring the autonomous car to realization. Increased Safety and Efficiency The theory goes that autonomous vehicles will be significantly safer than those driven by us. For example, new technologies will be able to keep these new and intelligent vehicles at a safe distance from other vehicles and also eliminate common driver mistakes such as excessive braking. And, its not only greater safety that’s being promised: there are potential benefits in traffic control and reduced congestion, in addition to significantly improved vehicle energy efficiency.

Obviously, there are number of obstacles yet to be overcome. Market acceptance is not a given and we can only begin to guess at the legal issues involved. However, we are now starting to see the go-ahead being given in the US for the development of rules and regulations for driverless cars. So it may not be too far away, and perhaps within just a few years. Research Issues Clearly, there are also problems that need to be addressed to undertake research into autonomous vehicles, such as cost and the risks associated with use of full-size vehicles, including all the legal issues. Several major car companies in Europe and the US, in addition to a global technology powerhouse or two, already have ongoing programs for prototype driverless cars. But, of course, these are companies that have superior resources and easy access to vehicle test facilities. Low-cost Autonomous Driving R&D However, an alternative lower cost approach is being taken at the University of Bristol. The university’s electronic engineering department has developed a low-cost autonomous driving system based on a comparatively small remote-control model car. The use of a reduced-size model immediately removed all legal issues and reduced costs by an order of magnitude. This innovative system has been used by a group of undergraduate students for their final-year projects to research into the key

technologies required for autonomous cars: software algorithms, in conjunction with the necessary control, image-capture and computational-processing hardware. Algorithms Each student developed an algorithm and implemented it on a specific digital signal processor (DSP). These algorithms enabled an extensive list of functionality, including: ‘real-time obstacle detection’, using stereovision (using a Texas Instruments DM648 DSP); ‘lane detection and tracking’; ‘alternative speed measurements’, based on image processing; and ‘night-time lead-vehicle-following’, based on tail-light recognition. The project car was tested with one DM648 and three DM6437 videoprocessing boards from TI, in addition to other basic components. These videoprocessing platforms were capable of simultaneously processing images and sending the results to the ‘decision-making’ subsystem for aggregation. System Framework The system framework comprises the chassis from a remote-control model car, modified to accommodate the required hardware. This includes: a video camera for image acquisition; the decision-making subsystem, implemented on a low-cost Pandaboard platform; and a control and safety subsystem, implemented on an open-source Arduino single-board prototyping platform. All the subsystems communicate via Ethernet technology, which also makes it easy to integrate

additional devices that support either Ethernet or Wi-Fi. For example, processing units could easily be added or removed to deliver the right balance of low power consumption and high computational performance. Additionally, the system was also made resilient to both software and hardware errors via the duplication of critical components. Standard Solutions Crucially, the use of standard software and hardware and the well-defined interface between components, in conjunction with first-class support delivered by Texas Instruments and RS Components, has enabled this innovative project to be implemented within a very limited timeframe. In this field at least, innovation and widely available standard components has meant the development of future automotive technologies is not confined only to the domain of the large corporations. FIND IT: Search the TI and Arduino range of products, with full supporting technical information at rswww.com/ti and rswww.com/arduino

Share your views... Got an opinion on the Bristol University project? Share it at www.designspark.com/etech eTech - ISSUE 8

23

New Zero Power RF technologies enable innovative designs and applications

The RFID industry has been developing integrated circuits which are gathering their energy from an external RF emitter called RFID reader, able to remotely energize, and communicate with those chips with read and write attributes. They have been used for years in identification, access control, contactless payment and asset tracking applications, and are unique in the sense that they allow a system to remotely communicate with a number of RF devices, while those devices operate at no on-board battery power cost. The main advantage over RF technologies such as Bluetooth and wifi is cost and power consumption, while the drawback a shorter range, within a few feet. Those devices could be categorized as shortrange zero-power RF products. They are made of a non-volatile memory, most commonly EEPROM technology, and a passive RF interface featuring a built-in communication protocol such as ISO15693. Over the years, chip manufacturers have been drastically improving their power consumption, in order to drive their RF performances up. Now, a new type of RFID products is emerging enabling system designers to integrate this technology into their boards, and to communicate with those chips from their embedded MCU using a standard serial interface. Those devices, such as STMicroelectronics’ M24LR64, are dual interface memories.

24

eTech - ISSUE 8

The good thing about those devices when embedded onto PCBs is not only they can operate in RF with or without on-board power, but -because they are optimized in power consumption- their I²C interface will operate at about 10 times lower consumption than regular EEPROM devices! Those devices can be embedded into a large type of electronic products, and enable a whole new range of use cases and applications. The less visible, but which can be used across all applications, and which can certainly generate cost savings is logistics: using long range industrial RFID readers will allow last minute parameter update or personalization. No need to open the box or break the package’s seal. Your customer finally needs to ship their electronic products to Germany instead of Spain. The RFID reader will access the content of the memory of each device, and will change the language settings from Spanish to German. When the system boots up, the main CPU will read the language settings value and will display German. Thanks to RF transceivers such as ST’s CR95HF chip, stand-alone RFID readers can be designed easily, or embedded into main units at limited cost. This enables the main unit to download all of the data logged in the memory by the sub-unit’s MCU. Applications such as portable healthcare/wellness devices, industrial sensors, loggers, event-recorders, but also tech gadgets can benefit from this

technology, enabling extremely power efficient systems, with reduced user interface costs, possibly water-proof products with connectorfree designs. At the same time engineers can design user friendly applications inside the main unit, which will process, analyze the information it downloaded from the sub-unit. Users can change their product’s parameters on-the-go, as well as download and display the information logged in it. This is only the tip of the iceberg. Manufacturers such as STMicroelectronics are preparing new versions of dual interface EEPROMs, with more innovative features. And the NFC technology, which is soon to be widely embedded into cell phones, is compatible with the RFID technology. As such, consumer cell phones will soon be able to communicate with those dual interface memories, enabling even more applications.

Share your views...

Got an opinion on how to get the best out of RFID? Share it at www.designspark.com/etech

NATURAL SELECTION

Easier, faster, clearer. Our new website is evolving to make finding products simpler than ever.

rswww.com

DESIGN TIPS

IN ASSOCIATION WITH

Solar Charger Portable energy for people on the move by Martin Kiel (Germany)

With renewable energy high on the agenda, this little project will appeal to everyone who would feel better charging their mobile or PDA from solar sources. A lithium-ion cell stores the sun’s energy in between charging sessions. Smart circuitry in the solar charger monitors the battery voltage and protects the battery from overcharging and deep discharge. The concept of recharging portable gadgets from the sun is by no means new [1]. On holiday any undetermined AC grid voltages and alien-looking power outlets would pose no problem, whilst we would also be able to recharge these essential gadgets even in places where there is no mains electricity.The only disadvantage is that the daytime, when the sun in question is available, is also when we most need to use mobile phones and PDAs. So the aim of this project is to capture and store those sun rays during the daytime so that we can put them to use at night for charging our gadgets. To keep this circuit as portable as possible, making it useful on a long walking tour for instance, the energy store chosen is a single lithium-ion cell of the lithium-polymer (LiPo) type. Circuit The solar charger consists of two modules: the charge regulator for the lithium-ion battery and a DC-to-DC converter for raising and stabilising the battery voltage (of between 3.0 and 4.15 V) to a higher value (Figure 1).

Features • Internal Lithium-Ion battery for storing solar energy • Versatile: your choice of batter and solar panel sizes • Direct charging/operation of USB devices. • Two switchable charging outlets: - constant voltage output (5 V, max. 500mA) - constant current (max. 150 mA) •

Battery management for internal battery: - Overload protection - Under-voltage protection with hysteresis regulator and load dumping

• Watchdog dropout protection • Compact dimensions • Complete firmware with source code downloadable from the Elektor website

26

eTech - ISSUE 8

The heart of the circuit in Figure 2 is an ATtiny13 microcontroller from Atmel, which monitors the battery voltage and controls the output of the solar cells. The solar charge regulator is arranged as a shunt regulator, which short circuits the solar cell if the battery voltage gets too high. As solar cells are short circuit-proof this arrangement does not pose any problems and offers the bonus that the current flowing through the feeder leads is not cut off abruptly. An economic advantage of this scheme is that T1 can switch without the need for an additional driver stage. A MOSFET IRF7413 is our choice for T1, which is definitely a bit of overkill for this application (IDmax = 13 A) but assures reliable activation by TTL level voltages without any problems. Acceptable activation is possible even at a reduced battery voltage of 4.1 V. The charge voltage reaches the battery from the solar panel via diode D1. The choice of this diode comes down to the solar panel used and the prototype used a 1N4007. However it is better, based on the voltage produced by the solar panel, to use a Schottky diode (e.g. BAT85), since these exhibit a lower voltage drop, raising the overall efficiency of the circuit.The battery in turn feeds the boost converter, which is equipped with an LT1302 from Linear Technology. The buffer choke L1 used has an inductance of 10 µH. In standby mode and with the DC-to-DC converter enabled, the circuit draws barely 30 mA of current. Despite this you have the option of removing jumper link JP1 to disable the DC-to-DC converter altogether. On the ground side the boost converter (and thus the output) is

DESIGN TIPS then passed to an LM317 linear regulator, which provides an output voltage of close to 7 V and also limits the charging current [4]. Using a value of 3.3 Ω for R17 we get a charging current of approx. 150 mA, which should not be exceeded, in order not to overload the boost converter LT1302 [2].

separable by a further IRF7413 MOSFET, meaning that the battery can be disconnected from the output for the sake of deep discharge protection (load dumping). Since mobile handsets do not all exhibit the same charging characteristics, the boost converter can be operated in two different modes, selected by a switch (S1). The first of these modes delivers 5 V to the USB connector, so that any devices that are charged from the USB supply can be charged in this way. The LT1302 is equipped with internal overload protection and switches off automatically if it overheats [2]. All the same, you should not allow the charge current for the USB device to exceed 500 mA. All devices that conform to the USB standard fulfil this requirement without exception [3]. The second mode of operation is intended for devices that require a constant current source for charging (for example some Nokia handsets). The author uses a Siemens BenQ S68 and this model requires a charging voltage of approx. 7 V to start the charging process. Subsequently it expects a constant charging current, until the mobile’s battery reaches a voltage of approx. 4 V. At this point the handset disconnects the charge automatically.

Programming and regulation Overall regulation of the circuit is handled by a microcontroller. The scheme uses two regulators with an interrupt-driven program; one looks after the charging terminal voltage and the other controls load dumping. The complete program flow is controlled by an interrupt occurring once every second. At the start of each interrupt LED D4 (yellow) is illuminated. Following this the existing battery voltage is compared against the stated limits for over and undervoltage states. Afterwards a new A-to-D conversion is initiated and LED D4 extinguished. Charging LiPo batteries The regulator for overvoltage short circuits the solar panel via T1 when the predefined maximum voltage of 4.15 V is reached and thus prevents overcharging the lithium-ion cell. To protect the battery from destruction the voltage of the cells must never exceed 4.2 V. For this reason the terminal voltage for charging is set at 4.15 V. Figure 3 clarifies the circuit of the charging system. The red curve shows how the charging current of the solar

This charging mode is achieved by a further stage that follows the boost converter. The output voltage of the boost converter is raised across R6 and R8 to 11.75 V. This voltage is

IC3 LM317LD

8

T2

Solar Panel

6

1

5

4

2

T3

1

LiPo 3V7 2000mAh

IRF7413

BAT

C8

C2 100u 16V

22k

22k

K3

USB-A 1 2 3

100n D5

R11

R13

4

MBRS360T3G

10uH

D2

100n

R6

C6

C5

100n

100u 16V

6 VIN

MISO 6

3

SCK

7

6

5

RST

1 5

ISP

PB1

IC1

PB4

3

3

PB2 PB5/RESET PB0/OC0A

PB3

2

2

R3

R5 22k

R2 82k

220R

4

SW FB

VC

LT1302CS8

ATTINY13V-10SU

R4

IC2

SHDN

GND 1

IT

7

SELECT OUTPUT VOLTS

4 5

PGND 8 R7

D4

D3

C4

yellow

red

10n

+5V

S1

1M5

1

R8 560k

2 MOSI 4

+11V75

BAT

Figure 2. Circuitry of the Solar Charger. An ATtiny microcontroller monitors charging and discharging of the buffer battery.

VBUS DD+ GND

solar charger

Li-Ion battery

charge controller

DC-DC converter

MP3 Player, mobile, PDA etc... 12 Figure 1. Functional diagram090190 of -the Solar Charger. Current from the solar panel is stored in a Li-Ion battery.

panel works, simplified by assuming that the value of the current never varies. The blue curve represents the battery voltage. As seen, the charging current flows until the maximum permissible battery voltage is reached. At this point the solar panel is shunted and the battery voltage drops again. At the next analogue-to-digital conversion the controller checks that the voltage of the battery is below the maximum permitted and allows charging current to flow once more. The battery voltage rises again now, occasionally even above the permissible limit, since the controller can measure the battery voltage only within the time windows defined. As the charge state of the battery drops, its voltage decreases constantly during the off-period of charging, so that the intervals between times when current flow is permitted again are constantly increasing. In practice the battery is completely charged when LED D3 (red) remains on all the time. Deep discharge protection by load release The second regulator, for load dumping, takes the form of a two-position controller with hysteresis. If the lowest permissible voltage is crossed during discharge of a lithium-ion cell, the DC-to-DC converter is disconnected from the battery by T2. The battery voltage then recovers slightly until the next interrupt occurs. If the load is now reconnected immediately, then the charging process sees the exact reverse scenario: the battery voltage would drop constantly, taking with it the charge state of the battery.

green

VOUT

C3

8

K5

R12

C7

100n

L1

270k

100n

R17

VCC

R1

C1

C9

BC847

100n

R10

MOBILE PHONE SUPPLY

R16

100R

PANEL_OFF

VBATT

BAT

R15

1

4 3

R9

1

220R

K2

5

220R

BAT

6

T1

IRF7413

7

2

7

K4

1k2

8

240R

LL4007G K1 1

3

ADJ

4M7

JP1 POWER_SAVE

+5V

R14

D1

22k

+11V75

22k

VBATT

VCC

3R3

VBATT

solar panel

090190 - 11

Continued page 28 > eTech - ISSUE 8

27

DESIGN TIPS exercise switch S1 in the DC-to-DC converter should be in 5 V (USB mode) position. With this load dumping test carried out successfully, the voltage is raised again until the green LED lights up. The data sheet of the Atmel controllers gives the internal reference voltage of the controller as from 1.0 V to 1.2 V, meaning that the controller needs to be calibrated for the exact voltage limits.

< Continued from page 27 I, U

t

090190 - 13

The software provides three variables for this (SolarCharger.h):

Figure 3. The charge regulator short-circuits the solar panel and cuts out the charging current (red), as soon as the voltage at the battery (blue) reaches the permitted maximum.

• MEAS_BATT_MAX: gives the maximum battery voltage for overload protection. • MEAS_BATT_MIN: gives the lower voltage limit for load dumping. • MEAS_BATT_MIN_MAX: gives the upper limit for reconnecting the load.

Lithium-ion batteries must not be discharged too deeply, as this causes permanent damage. For this reason the terminal voltage during discharging is set here as 3.0 V. When this is reached, the hysteresis regulator for load dumping waits until the battery voltage is again at a higher level (e.g. 3.5 V) before load dumping is deactivated again.

Benchmark values for these limiting values are given in Table 1 and are calculated as follows: The A-to-D converter of the ATtiny has a resolution of 10 bits, i.e. 1024 separate values. The internal voltage source is indicated as a nominal 1.1 V. Using the given values of the voltage divider R1 and R2 and a maximum battery voltage of 4.72 V, the A-to-D converter will deliver a value of 1024. From this we deduce that one bit of the converter corresponds to 4.6 mV. In this way we can calculate all values for the voltage limits. The values in Table 1 do not correspond to the exact value, however, on account of variance in the reference voltage. For this reason during the functional test it is important to note at which voltage each limit is reached. The correct value for the respective voltage limit can be calculated as follows:

Construction, commissioning and calibration The PCB of the solar charger (Figure 4) uses predominantly surface-mount components (SMD devices). All of these are installed on the upper side of the board apart from up to four resistors. The software for the microcontroller, including source code, can be downloaded from the Elektor website [6]. If you don’t feel inclined to program the ATtiny yourself, a ready programmed controller can be bought from the Elektor Shop. As with any other project, a functional test is the next step after construction. This consists primarily of testing for effective protection against overvoltage, undervoltage and deep discharge. For this you will need a programmable power supply, which is connected in place of the Li-Ion battery.The voltage is first set to 3.5 V and the function of the DC-to-DC converter checked (output current and voltage). After this the voltage is raised slowly until the red LED D3 begins to light. T1 should now short circuit the solar panel. Now the voltage is slowly lowered until the green LED D5 goes out. For this

Limit new =

Figure 5. Cabling of the four solar modules, which are connected in parallel.

Figure 6. Schottky diodes ensure that no reverse current can flow through a module that is in shadow.

Utarget × Limit actual U actual

Solar panel and battery sizes The prototypes used Kokam brand LiPo cells with 2 Ah capacity. These batteries, widely used by aircraft modellers, have the advantage of being flat and thus space-saving. Their high performance and discharge current make them relatively expensive, however. As high currents are not involved in our application we can get

Figure 7. Solar module arrangement in the author’s prototype charger.

Table 1. Battery voltage limits relative to microprocessor internal reference. The exact value must be determined by calibration (see text). Uref [V]

Ubatt [V]

28

eTech - ISSUE 8

1.0

1.1

1.2

4.15

990

900

825

3.50

835

759

696

3.00

716

651

596

Figure 8. Internal view of the first prototype. The PCB is connected directly to the solar modules here.

DESIGN TIPS away with more economical batteries, for instance the type 18650 round cells used in laptop batteries. The size of battery used in the charger is determined chiefly by the load created by (in other words the capacity of) the mobile phone battery to be recharged. The latter varies between 600 mAh (e.g. Siemens BenQ S68) and 1.6 Ah (e.g. Apple iPhone). If we start with the assumption that the boost converter of our solar charger has an efficiency of 80% and the battery has adequate capacity, then in order to fully recharge a 1.2 Ah mobile phone battery the charger battery needs to have a minimum capacity of 1.44 Ah. Taking this further, accepting that the battery in the solar charger will not always be fully charged, this means that a 2 Ah battery would be a safe choice. Whatever these values, it is clear that the storage battery in the solar charger must always have greater capacity than the one in the device being recharged. The capacity of the battery will then determine the size of the solar panels. In the prototypes the solar panel was assembled from four solar modules wired in parallel, giving a nominal voltage of 5 V at a nominal current of 81 mA. This is a common size in trade catalogues. In Figure 5 you can see how we wired the four solar modules at Elektor Labs. Each of the positive connections was connected to the common +ve bus via a 200 mA Schottky diode (BAT85) arranged to permit current flow from the module to the bus (see close-up photo Figure 6). These diodes block any backward current flow through individual modules when they are in shadow or are delivering a reduced voltage to the others for some other reason. This set-up provides a total charging current of 324 mA, meaning that the 2 Ah storage battery should be fully charged in six hours (in theory). These diodes were omitted in the author’s original prototype (Figure 7 and Figure 8), which differs in a few details from the Elektor version presented here. The reverse current through an obscured (or underperforming) module is not really critical but it will reduce the output current and hence the performance of the solar panels. The Schottky diodes block the reverse current but also introduce a permanent loss in performance on account of the voltage drop of about 0.4 V at 80 mA, equivalent to around 8 % at maximum output of the solar modules used here. Nevertheless Elektor Labs recommend using these diodes.

Component List Resistors

RS Stock No.

Capacitors

RS Stock No.

Inductor

RS Stock No.

Semiconductors

RS Stock No.

SMD0805, 0.125W, 1%, if not shown otherwise) R1 = 270kΩ565-958 R2 = 82kΩ566-755 R3,R4,R9 = 220Ω566-913 R5,R10–R13 = 22kΩ566-226 R6 = 4.7MΩ679-1500 R7 = 1.5MΩ679-1058 R8 = 560kΩ566-777 R14 = 240Ω679-1125 R15 = 1.2kΩ565-926 R16 = 100Ω566-907 R17 = 3.3Ω721-8523 C1,C3,C6–C9 = 100nF (SMD0805, 10%) C2,C5 = 100µF 16V, 10%, tantalum, SMD C4 = 10nF (SMD0805, 10%) L1 = 10 uH, 2.7 A, 0.053 Ω, 20 %, ferrite core 

648-0979 496-3646 264-4371 724-5297

D1 = 1N4007 (MELF), e.g. LL4007G or BAT85 (see text) D2 = Schottky diode 3A, 60V (e.g. MBRS360T3G, On Semiconductor) D3 = LED red, 25mA, SMD1206 D4 = LED yellow, 25mA, SMD1206 D5 = LED green, 20mA, SMD1206 T1, T2 = IRF7413 (International Rectifier) T3 = BC847 SMD (e.g. BC847CLT1G, On Semiconductor) IC1 = ATtiny13V-10SU (Atmel), programmed IC2 = LT1302 (Linear Technology) IC3 = LM317LD (e.g. from ST Microelectronics)

Miscellaneous

652-7466 545-2096 490-1569 486-0496 486-0531 543-2468 545-2765 629-2198 545-6559 714-0795

RS Stock No.

K3 = USB-A connector, SMD (e.g. Lumberg 2410 06) S1 = Micro slide switch, 2-pole changeover 702-3564 K5 = Connector strip 6-pin, twin-row, 2.54mm spacing 681-2947 JP1 = 2-pin pinheader  717-6589 JP1 = Jumper, 0.1 in. lead pitch 251-8569 LiPo battery 2000 mAh, 15C, 3.7V,  615-2444 ASI-OEM solar panel 4.8V/80mA or 5V/81mA or similar Schottky diodes BAT85 for parallel connection of the panels 300-978 PCB, order code 090190-1  www.elektor.com/090190

In principle larger solar modules, as described in [1], can also be used, for example those with a voltage of 12 V. The controller ensures that the voltage does not exceed critical limits and thus protects the battery. All the same, a panel of such large size would never be able to deliver full performance, as the voltages will always be well below the optimal operating point. Literature and Links [1] Portable Solar Panels – Portable Energy On The Move, Elektor June 2009 [2] D  ata sheet LT1302, Linear Technology http://cds.linear.com/docs/Datasheet/lt1302.pdf [3] Universal Serial Bus specifi cation, Revision 2.0, 27 April 2007, www.usb.org [4] Data sheet LM317, Linear Technology http://cds.linear.com/docs/Datasheet/lt0117.pdf

Figure4. The PCB of the Solar Charger uses mainly surface-mount components that are easy enough to solder. Four of the resistors are located on the underside of the board.

[5] Data sheet Attiny13(A), Atmel http://www.atmel.com/dyn/products/product_card.asp?PN=ATtiny13A [6] Project page with software download and ordering details atwww.elektor.com/090190 eTech - ISSUE 8

29

Energy-efficient and Renewable Technologies By Andrew Back - Co-founder, SolderPad

Open source techniques are being employed in the development and provision of access to an increasingly diverse range of technologies. In this article we’ll take a look at two comprehensive open source projects that incorporate elements of mechanical, electrical and software engineering. One that is concerned with building a hydrogen fuel cell electric car, and another with making wind turbine designs freely available to all.

A highly energy-efficient vehicle

Open Source

Riversimple is a UK-based company that was founded with the aim of producing highly energy efficient vehicles for personal transport. In 2009 they unveiled a technology demonstrator for the Hyrban, a two seat car with a 240 mile range that achieves an energy equivalent of over 300 mpg. One year later securing a deal with Leicester City Council to deliver 30 vehicles as part of a pilot scheduled for 2012. With ambitious plans to have 84,000 cars in use across the UK by 2020.

30

The Hyrban is built around what has been termed a “network electric platform”, consisting of a hydrogen fuel cell power source, a bank of ultracapacitors, 4 in-wheel electric motors and a control system. Regenerative breaking is employed and recaptures around 50% of the energy that would have been lost as heat. This is stored in the ultracapacitors and provides in the order of 80% of the energy required for acceleration. Thus allowing the car to have a much smaller fuel cell than would otherwise be required in order to to cope with peak energy demand.

opted for open licensing and the IP is held in trust by a nonprofit organisation. Setting up the 40 Fires Foundation for this purpose, and operating it as a separate legal entity with a board of trustees that is two thirds independent. Riversimple’s open source approach allows them to focus on innovation, leads to simplified commercial relationships and encourages the creation of an ecosystem of parts, or even whole cars. Indeed their distributed manufacturing model is based on a network of smallscale factories, that will lead to greater resilience to deal with fluctuating demand and provide increased flexibility to enable vehicle customisation.

The novel approach that Riversimple have taken extends beyond their choice of technology and to their business model and Intellectual Property (IP) strategy. Resolutely focused on reducing the environmental impact of personal transport, they have decided that the cars will not be for sale and will only ever be leased. In selling a service rather than a product they are motivated to build cars that are low maintenance and with a long operating life, in addition to being highly efficient. Rather than taking the usual route of seeking to secure exclusive rights via patents, Riversimple have

eTech - ISSUE 8

Image ©Rive Image ©R rsive imrsim ple LL pleP LLP

Open renewables UK-based non-profit organisation Onawi was founded by a team with a background in open source software and open knowledge. Its stated aim is to “directly contribute to a just transition towards climate change mitigation by making designs of wind turbines freely available to all”. In support of this it has partnered with Danish research and development and technology transfer organisation, the Nordic Folkecenter for Renewable Energy. Entering into an agreement that will see Onawi release specific Folkecenter designs for 150kW wind turbines This “medium sized” class of wind turbine is of particular interest due to its suitability for manufacture and use in low and middle income countries. Since the technology selected was developed in the 1980s it does not require advanced materials and difficult to manufacture components. Furthermore, time has proven it to be low maintenance and reliable, with turbines operating in the field for over 20 years. Onawi plan to release the designs under an open licence such as those from Creative Commons or GNU. Working with distributed teams and commercial and community partners, to develop transferable in-country skills. Fostering collaboration across projects and driving participation in the further development of designs.

Image ©Preben Maegaard

Image ©Nordic Folkecenter for Renewable Energy

Continued page 32 > eTech - ISSUE 8

31

< Continued from page 31

Ima

©R

iver

sim

Open Source

ge

32

ple

LLP

Conclusion Riversimple are using open source as a means of facilitating a novel approach to manufacturing that will lead to business agility and reduced risk, whilst enabling external participation in the design process. Open source software has demonstrated how participation and a sense of shared stakeholdership drives the creation of technology platforms. As these grow and an ecosystem is established benefits accrue in the form of complementary technologies, shared maintenance overheads and reduced costs. Trust is fundamental to platform development and the creation of the 40 Fires Foundation will serve to build this.

a strategy of technology transfer that is underpinned by open licensing, online collaboration and the development of in-country expertise and manufacturing capabilities. If successful Riversimple will create a new marketplace and will occupy a key position within this. Onawi have an opportunity to effect positive change on a global scale and in a manner that will provide the maximum benefit to local economies. In both cases a radical and potentially disruptive approach to a significant environmental challenge is being adopted.

Onawi represents a new breed of non-profit that is working to address global problems in a truly sustainable manner. With

Share your views... Got an opinion on how Riversimple are using open source techniques to develop energy efficient applications? Share it at www.designspark.com/etech

eTech - ISSUE 8

Saving Energy, Saves Our Planet, Saves Your Money Upgrade to EC fan systems using our Energy Saving Calculator

Our new energy saving calculator tool will help you to find savings of up to 65% when upgrading exsisting AC fan systems to our EC technology. Using this app will provide typical savings in not only annual kWh’s, annual cost savings (£) and payback in months but also the environmental benefits with reduction in CO2 emmissions and carbon savings (tonnes). To download this app go to www.rs-components.com/ebmpapst or via the App Store

Electronics Extras

RS Essentials NiMH batteries Kinder for the environment than alkaline equivalents n A comprehensive range of sizes and capacities, plus tagged versions for permanent installation. NiMH offers quick charging times and no memory effects. RS Web search term: rs nimh battery

Weller Energy Efficient Soldering System Antistatic touchscreen, intelligent sleep mode and multi-language display - the WX 2 from Weller has been designed from customer suggestions. n High capacity power supply allows two irons to be used simultaneously. Robust touchscreen operation which is chemical and temperature resistant. Automatic stand by mode is activated by sensor in handle of iron which saves energy and prolongs life RS Web search term: Weller WX

ESD Tool Kit 6-piece anti-static kit for use in SMD assembly n Kit contains five types of SMD tweezers including sickle shaped, 30°, 35°, tip angled and straight and a pair of mini side cutters housed in an ESD safe plastic case RS Web search term: 725-2703

Eco-logic freezer spray from Rocol ®

Upgrading to eco-logic for one year will eliminate green house gases equivalent to flying from London to New York n Low global warming potential. Non-flammable. Cools to -40°C. Multi angle spray allows access to difficult to reach areas. Available in 200 and 400ml cans RS Web search term: 733-5322 and 733-5328

34

eTech - ISSUE 8

See more online - Over 5,000 new products are

Electronics Extras EcoWire Environmentally friendly hook up wire n Alpha Wire’s EcoWire hook-up wires use flexible Noryl insulation to provide an environmentallyfriendly alternative to PVC thats fully recyclable and helps manufacturers meet WEEE requirements. RS Web search term: ecowire

Dymo Rhino 5200 label printer With pre-programmed symbol library n Quickly create crystal-clear, professionally formatted labels for wires and cables, terminal blocks, 110 blocks, electrical and patch panels, shelves, racks, equipment machinery and more. RS Web search term: 686-8118

LED Beacons Low profile LED beacons from warning specialists Moflash n Incorporating 12 ultra bright surface mount LEDs this beacon range offers an economic solution for a wide range of general signalling applications. AC and DC options available, flashing or static operation and choice of four colours available. RS Web search term: LED80

Fluke 115 multimeter Compact true-rms meter for electrical and electronic testing applications n Designed with electronic troubleshooting in mind, with a wide variety of measurement parameters, including frequency and capacitance. RS Web search term: 616-1454

S7-1200 PLC Starter kit All you need to start designing using Siemens latest compact PLC platform n The S7-1200 PLC is an evolution of Siemens’ popular S7-200 family and takes compact PLCs to the next level, and using this starter kit is the quickest and most cost effective way to begin developing with this next generation PLC system. RS Web search term: 668-3131

added at rswww.com/electronics every month

eTech - ISSUE 8

35

Robots

to the Rescue Dr William Marshall, RS Components

Say ‘Robot’ to anyone and an image will flash into their minds of a humanoid machine, intelligent and capable of performing any human task, only better.

Image

36

©iRob

ot

eTech - ISSUE 8

An older generation will think of ‘Robbie’ in the film Forbidden Planet. Somewhat younger people will remember C3P0 from Star Wars and more recently the army of domestic robots in I, Robot, or ‘Data’ in Star Trek: The Next Generation. What’s the common factor here? Obvious really: they aren’t real, they’re science fiction. The Reality Gap Robots occupy a special place in the minds of most people: unfortunately most of what they know has its origins in Hollywood. It is easy to imagine what a robot should be able to do, but making it happen is rather more difficult. Let’s look at an example: a recent episode of a TV crime drama featuring a brilliant university professor who uses mathematics to solve crimes. This story involves a train wreck with passengers trapped in a coach partly crushed by a tanker full of poisonous chemicals. Our maths professor just happens to have a set of intelligent swarming robots programmed to search for survivors and map a route to them through the debris. Of course we don’t actually see these 6-wheeled toy-sized marvels moving around amongst the devastation, co-operating to bridge gaps, recognising pathways, climbing over obstacles and sending video back to the laptop computer outside. The fact is, these little buggies with a ground clearance of 10mm would get hung up on the first piece of bent metal they encountered. We forget just how flexible a machine the human body is, coupled with an ability to process information from a huge range of sensors and make decisions based on a massive database of past experience. Trying to imitate ourselves in metal and plastic is proving to be a challenge of immense proportions. However, a ‘real’ robot must have some advantage over humans in dangerous situations and the recent Fukushima nuclear power plant disaster in Japan provides an ideal testing ground for non-fictional hardware.

Development of humanoid robots has got as far as machines that walk, run, dance, climb stairs, kick a ball about and get up if they fall over. Not a lot of use in a disaster zone.

The Disaster Scenario The Fukushima site suffered from two natural attacks: an earthquake followed by flooding from a tidal wave. To the hazards of damaged buildings with flooded corridors and rooms partially or completely blocked with rubble, must be added radiation in levels ranging from lethal to tolerable for short periods. If this wasn’t bad enough, the reactors were unstable and even undamaged control and monitoring equipment was inoperative because all outside electrical power to the site had been lost and the standby diesel generators were flooded out. Continued page 38 > eTech - ISSUE 8

37

< Continued from page 37 Robots to the rescue….or not Robots should be able to make a major contribution in each of these areas: 1. Reconnaissance to assess the type and scale of the tasks.

still run into trouble in a high-radiation environment. Research is underway to use multiple UAS in a swarm specifically for the purpose of reconnaissance and communication in a disaster zone. Fortunately this is one area of research where the hardware necessary to test out ideas does not have to be very expensive: the AR.Drone is a quadricopter fitted with cameras and some pretty sophisticated electronics aimed at the entertainment market.

2. Rescue of survivors. 3. Repair of critical systems to render the situation stable. 4. Recovery of victims. 5. Rebuilding the facility as necessary. Currently there are no robots available that could perform all these tasks and in fact they have only been any real use in the first, reconnaissance role. Powerful, intelligent humanoid robots like the fictional ‘Data’ from Star Trek would be ideal. Development has got as far as machines that walk, run, dance, climb stairs, kick a ball about and get up if they fall over. Not a lot of use in a disaster zone. What we have got are tracked vehicles designed for military use disarming terrorist bombs such as Packbot from iRobot and Talon built by Foster-Miller. This type of vehicle can at least climb over reasonable amounts of rubble and even use an arm to clear debris to a limited extent while providing a TV picture to the operator. These machines have little ‘intelligence’ and are best described as Remotely Operated Vehicles or ROVs. They must be heavy and strong to withstand falling debris, but this means they cannot move in confined spaces and might cause further injury to any survivors they come across. At Fukushima they must be shielded against intense radiation as well, because electronics is just as susceptible to damage as human flesh. This makes the machine even bigger and heavier. These working conditions even make radio control difficult as anyone who runs a WiFi network in a building with thick walls will testify. The ‘swarm’ concept may provide a solution to the communication problem with many vehicles acting as relay stations for the signal. There is another class of robot that can be used in the reconnaissance role: the Unmanned Aircraft System or UAS. Thanks to microelectronics providing the computing power for real-time control systems there are microhelicopters bristling with cameras able to fly around inside a building. Possible candidates for disaster monitoring include the Honeywell T-Hawk Micro Air Vehicle. Once again though, it was developed for military use, comes with a high price tag, but could

38

eTech - ISSUE 8

Conclusion The brutal fact is that robot technology has a long way to go before it catches up with public expectations. In the list of five areas for robotic help in disaster rescue we are still on item 1. One reason for this is that most research is military-based and there is only a limited overlap with the needs of disaster rescue teams. As long ago as 2001 the Japanese were developing a robot [6] for measuring radiation levels in a damaged nuclear plant but even this doesn’t seem to have progressed much beyond a radiation-hardened tracked vehicle with a camera. The world-wide RoboCup competition [7] initially set up to encourage development of a robotic football team has a parallel contest for rescue robots. All participants are required to disclose technical details of their designs in order to push the technology forward in this badly neglected area of research. References [1] Tracked robots for military and safety applications www.irobot.com/gi/ground/ [2] Unmanned systems and vehicles www.qinetiq-na.com/products-unmanned-systems.htm [3] Honeywell T-Hawk Micro Air Vehicle www.thawkmav.com/ [4] Swarming Micro Air Vehicle Network (SMAVNET) http://lis.epfl.ch/smavs [5] AR.Drone flying video game http://ardrone.parrot.com/parrot-ar-drone/uk [6] Remote Surveillance Squad http://www.jaea.go.jp/jaeri/english/press/2001/010314/index.html [7] RoboCup Rescue competition http://www.robocuprescue.org/index.html

Share your views... Got an opinion on what’s needed to push forward robot technology? Share it at www.designspark.com/etech

DESIGNSPARK PCB Award winning free software, only from RS DesignSpark PCB is our award winning free-of-charge design tool. It comes with limitless options and now includes a 3D viewer capability. Download at designspark.com and get that creativity flowing.

*Winner of New Product of the Year award presented by Printed Circuit Design and Fab, April 2011

www.designspark.com

WIRED BY

The home of online resources and design support for engineers DesignSpark has become the fastest growing online community for engineers, with more than 50,000 members now registered. DesignSpark is an online gateway that gives engineers trusted and reliable information and resources, bringing together user generated reviews and new free-of-charge tools to speed up the design process.

40

eTech - ISSUE 8

Spark Store - Free design tools for engineers DesignSpark offers free-of-charge access for members to a range of design tools, hosted in the Spark Store. Included in the store is DesignSpark PCB, RS Components free award winning PCB design software, and PCB Converter for SketchUp, enabling Intermediate Data Format (IDF) files to be converted into a format for Google SketchUp; amongst a range of tools from Tektronix Probe Selector, Texas Instrument’s Power Stage Designer to Atmel’s FPGA Designer.

POWERED BY

Meet the experts Andrew Back Co-found SolderPad

Design Centre The Design Centre contains technology tips and hints posted by DesignSpark members. The centre will keep engineers up-to-date with the latest design trends, as well as containing links to a range of RS website tools, making component selection and integration into design software packages fast and simple. Reviews A major feature of DesignSpark is a library of independent reviews for development kits and evaluation platforms, provided by engineers, for engineers. This feature allows users to post comments and star ratings for each kit. Covering a range of up to 1100 microcontrollers, microprocessors, analogue and FPGA development kits, with new kits being regularly added. Partner Portal The partner portal has been specifically created in order to allow DesignSpark members to connect with companies and individuals who can help provide information, support or resources that will enable faster design development. Featured partners already include a mix of component manufacturers, design consultants and contract electronics manufacturers, with new partners being added on a daily basis. Connect The connect area enables members to find other engineers and experts within a technology area, to form a professional network and to be able to directly message members that your connected to.

New

Design Challenge Competition See page 05

www.designspark.com

“I served an apprenticeship in electronic engineering and gradually moved into computing. I’ve been an advocate of open source software for some time and recently acted as BT’s Open Source Strategist. In response to a significant growth in the application of open source techniques in hardware design, I founded the Open Source Hardware User Group in April 2010. I left BT earlier this year to co-found SolderPad, a startup which is developing technology to support the online, collaborative development of electronics.

Paul Clarke Embedded Electronics Engineer at ebm-papst I have worked for a number of companies including Herbert’s the supermarket checkout scale manufacture, PI Research who develop electronics for motor-racing, Tyco electronics and now at I’m ebm-papst UK where I have been for 5 years. I call myself an embedded electronics engineer which means I get involved in everything from writing specs, full design cycle, building prototypes, laying out PCBs, testing and pre-production. I develop embedded control systems for the Heating, Ventilation and Air-Conditioning (HVAC) and Refrigeration and Air-Conditioning (RAC) markets using PIC micros and writing code in embedded C and Assembler.

Ioannis Kedros Electronics Engineer at ARM As a system design engineer for ARM, I’ve studied engineering in Greece, Finland and the UK and have been awarded first prize for numerous International Electronics Design Competitions, ranging from Algorithm Design to Electronic Design (SchmartBRD). Read the latest reviews and blogs at www.designspark.com eTech - ISSUE 8

41

INDUSTRY NEWS

Storing Green Electricity as natural gas By Marion Horn

Scientists have devised a new way of storing energy. They convert electricity generated from the sun and wind into gas and store the energy in existing pipes and gas holders. Wind and sun are sources of clean energy. But the wind cannot always be relied on to bow, nor does the sun always shine. Energy stores are needed because when it’s blowing a gale, wind power plants deliver more electricity than the power grid can handle. High-capacity storage systems – such as redox-flow batteries and pumped-storage power plants – can then supply energy during windless periods. A partnership between business and research has found a new way of keeping energy on tap by storing surplus electricity generated by wind turbines and photovoltaic systems as climate-neutral methane – a natural gas substitute. Natural gas has traditionally been converted into electricity, but now the cooperation partners are taking the opposite route. Using a new process, the research scientists are converting electricity into a synthetic natural gas.

Well-known technologies newly combined: hydrogen electrolysis and methanization The process was developed by the Center for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) in cooperation with the Fraunhofer Institute for Wind Energy and Energy System Technology IWES. The Stuttgart-based partner company Solar Fuel GmbH is currently preparing its industrial implementation. “With the rapid expansion of renewable energy, the demand for new storage techniques is increasing sharply. We see a very big market here, because the long-time storage of renewable energy is the key to the expansion of wind and solar power”, explains Managing Director, Dipl.Ing. Gregor Waldstein. A

demonstration system built for Solar Fuel in Stuttgart is already running successfully. Construction of a much larger facility, in the double-digit megawatt range, is scheduled to commence in 2012 So how does the process work? Dr. Michael Specht from ZSW explains: “Our demonstration system in Stuttgart uses electrolysis to split water from surplus renewable electricity, producing hydrogen and oxygen. A chemical reaction of the hydrogen with carbon dioxide causes methane to form – which is the same as natural gas, only synthetically produced.” For the first time, the technologies of hydrogen electrolysis and methanization are being combined. The gas can not only be stored, but can also be used as fuel or for heating and refrigeration. Liquid fuels such as gasoline and kerosene can also be produced from it.

Share your views... Got an opinion on the viability of green electricity conversion? Share it at www.designspark.com/etech

42

eTech - ISSUE 8

Panasonic New V-FT series Low ESR SMD Aluminium Electrolytic Capacitor

Panasonic introduces the latest LOW ESR SMD Aluminium Electrolytic Capacitor. This product disposes of high capacitance and low resistance values combined with a smallsized case. The outstanding performance of the new V-FT series is achieved by highcapacity electrode foil and sophisticated Panasonic Low resistance technology. Compared to the leading low ESR Panasonic series (V-FK and V-FP) and to comparable competitor products, the new V FT series is miniaturized by 1 case size with same CV values and Low resistance. The V-FT series corresponds to future market needs requesting high performance components in small size ratio. Features compared to V-FK series • Miniaturization & weight reduction = Downsizing by up to 60% • Stable operation & high efficiency = ESR reduction down to 50% • Ripple current increase up to 1.4 times • High reliability & long lifetime = 2000h at 105°C • High temperature lead-free reflow soldering

Applications • Switching Power Supplies • DC/DC converter • Automotive equipment • Industrial electronics • Digital devices • Telecommunication, e.g. Base stations • Smart Meter • New designs for high efficiency and miniaturisation

Technical Data • Voltage range 25 VDC to 50VDC • (6.3 VDC to 16VDC will be available from Q4 2011 onwards) • Capacitance range 10 uF to 820 uF • (10 uF to 2200 uF will be available from Q4 2011 onwards) • Temperature range -55°C to +105°C • Endurance 2000h at 105°C • Size B to G case size (Ø4 to Ø10mm) • Soldering Peak temperature 260°C (Ø4 to Ø6.3mm) / 245°C (Ø8 to 10mm)

www.rs-components.com/panasonic

IN

LLIGENT INTELLIGENT SOLUTIONS FOR INDUSTRIAL MACHINERY. WE’RE IN IT.

RZ Relay

PT Relay

SR6 Relay

www.rs-components.com/teconnectivity TE Connectivity’s only obligations are those stated in TE’s General Terms and Conditions of Business (http://www.te.com/aboutus/tandc.asp) TE expressly disclaims any implied warranty regarding the information contained herein, including, but not limited to, the implied warranties of merchantability or fitness for a particular purpose. TE Connectivity, TE (logo) and TE connectivity (logo) are trademarks. Other logos, product and/or company names might be trademarks of their respective owners.