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  1. 1. ion61002 [Microcontrollers & Embedded • Analogue • Audio• Digital • Test & Measurement] s nic a t agemu February 2011 AUS$ 14.50 - NZ$ 17.50 - SAR 102.95 £ 4.80 5p m 2 co ✚ Telephone-to-VoIP Adapter on www.elektor.co www.elektor.com www.elektor.com w.el TimeClick Programmable Camera Controller Geolocalization without GPS Where am I? Where am I headed? Light Alarm Clock Programmed Sunrise ✚ Ultimatic CW Keyer For high-speed telegraphy operators R08 ✚ Contactless Thermometer Are you running an infrared temperature?
  2. 2. 61002 LPC11C2x CAN MCU Series Industry’s first integrated CAN microcontroller and transceiver with CANOpen® Drivers. Features high-speed CAN transceiver and 32-bit LPC1100 MCU Higher code density powered by Cortex-M0 Superior performance than 8/16-bit microcontrollers Enable development of a wide range of industrial networking applications www.nxp.com/microcontrollers
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  4. 4. 61002 Communicate Surveys and feedback indicate that Elektor readers expect to find a large variety of articles, viewpoints and tech- nical approaches in the magazine. For this February 2011 edition we have done our utmost to pack the pages ahead of you with a wide variety of topics with a slight accent on communication, our announced theme of the month. Let’s see what’s communicated on communication. A telegram-style explanation is presented on the famous OSI layer model, which is 6 Colophon widely used in computers and networks. Who’s who at Elektor magazine. There’s also a handy VoIP adapter that 8 News & New Products enables the good old analogue telephone A monthly roundup of all the latest in set gathering dust in the cupboard to electronics land. be used for state of the art VoIP com- munication. The adapter features a USB 14 OSI from ISO port for connecting to the computer and “Seven Bridges You Shall Cross” before is designed to work under Linux. If you you can eat your OSI Cake and have it the like to mess around with old computer ISO way. gear you’re sure to have fun with the article on a DIY Texting (SMS) gateway 16 Reradiating GPS Antenna based on a scrap PC and a cellphone your To keep you headed in the right direction, spouse or children have classified as ‘RIP’ here’s a quick and cheap method to or ‘unfashionable’. There’s plenty of ICT overcome poor GPS signal levels in a car. scrap material around, and it’s often free for collection. Communication at the 18 Gentle Awakenings hands-and-feet level is also covered in This circuit has advanced features geared this edition with the AlphaLED (Alpha- to waking you up ‘sunrise style’. betLED) letter shaker, a small board that ‘writes’ messages in the air if you wave it. 24 Ultimatic CW Keyer There are a few messages in memory, but Morse is not dead and this project is for you can also create your own words or high speed telegraphers having mastered text by on the fly programming. the Ultimatic ‘squeeze’ keying method in Finally we have a circuit that bridges combination with a CW paddle. 100+ years effortlessly, happily combin- ing Morse (the pundits say CW) with PIC 32 Educational Expansion Board microcontroller technology. The Ulti- Flexible, multi-talented and versatile are matic keyer is for experienced CW fans, some descriptions that fit this expansion maintaining the correct time relations board for our popular ATM18 controller. between dots, dashes, words and lines, besides doing a lot more. The project 38 Geolocalization without GPS was designed to support the famous WiFi spots and triangulation methods can Ultimatic mode, a system that reduces be used advantageously to pinpoint your hand movement on part of the telegraph position with remarkable accuracy. operator and so allows amazing speeds of up to 100 wpm to be achieved. 43 E-Labs Inside: And more ... just browse this edition Here comes the bus (2) because there are many more interest- The guys at Elektor labs delve deeper into ing articles I am unable to communicate their plans to develop a proprietary bus. at the risk of exceeding the 360 word limit the page layout colleagues have 45 E-Labs inside: Design tips communicated over coffee and a piece for instrumentation amplifiers of OSI cake (page 14). Input noise and ADC resolution are Jan Buiting, Editor important considerations in very sensitive measurement systems. 4 02-2011 elektor
  5. 5. 61002 Volume 37 CONTENTS February 2011 no. 410 18 Gentle Awakenings The light alarm clock described here is built around a microcontroller and can switch and dim an existing lamp (or lamps) fitted with an incandescent bulb (normal or halogen). It has several advanced features and its purpose is to wake 48 Contactless Thermometer This thermometer employs an infrared you up without a startle. sensor to read an object’s temperature without touching it. 53 TimeClick A controller for sensor, sound or time driven photography at an advanced level. 58 MIAC Controlled 24 Ultimatic CW Keyer Underfloor Heating System A stunning application of Elektor’s The circuit discussed in this article was developed specially for the squeeze Flowcode powered super PLC. paddle CW key but works great with single lever keys too. It looks after a lot of 60 Linux’ed time related issues such as the pauses between dots and words, fully support- Telephone-to-VoIP Interface ing the renowned Ultimatic mode. Connect your vintage telephone set to the world of VoIP and start phoning with no fears of a massive Telco bill. 65 AphaLED Shaker This little gadget when shaken prominently shows a letter in the air. 53 TimeClick 68 How to Get your Own USB ID Less than one LSB of all people designing TimeClick controls a digital SLR camera without human intervention using a stuff to work on USB actually manage to wired connection. It can take photographs at fixed or random time intervals or get their own ID in chips. in response to sensor input, which makes it suitable for various purposes from 70 TEXT Me! From 1, PC junkyard HDR photography to sound-triggered pictures. An old PC and a surplus cellphone together make your very own text messaging system. 75 Hexadoku Our monthly puzzle with an electronics touch. 60 Linux’ed 76 Retronics: Slide Rules & Telephone-to-VoIP Interface The Electronic Engineer Regular feature on electronics ‘odd & Start phoning with no fears of a massive Telco bill. The powerhouse board de- ancient’. Series Editor: Jan Buiting scribed here works under Linux using the renowned Asterisk IP PBX software, 84 Coming Attractions and at a stroke enables you to use your home telephone set (dare we say ‘vin- Next month in Elektor magazine. tage’) to connect to the VoIP world. elektor 02-2011 5
  6. 6. 61002 Elektor International Media provides a multimedia and interactive platform for everyone interested in electronics. From professionals passionate about their work to enthusiasts with professional ambitions. From beginner to diehard, from student to lecturer. Information, education, inspiration and entertainment. Analogue and digital; practical and theoretical; software and hardware. ANALOGUE • DIGITAL MICROCONTROLLERS & EMBEDDED AUDIO • TEST & MEASUREMENT Volume 37, Number 410, February 2011 ISSN 1757-0875 Elektor is also published in French, Spanish, American Editorial secretariat: English, German and Dutch. Together with franchised Hedwig Hennekens (secretariaat@elektor.nl) Elektor aims at inspiring people to master electronics at any editions the magazine is on circulation in more than 50 personal level by presenting construction projects and spotting countries. Graphic design / DTP: Giel Dols, Mart Schroijen developments in electronics and information technology. International Editor: Managing Director / Publisher: Paul Snakkers Wisse Hettinga (w.hettinga@elektor.nl) Publishers: Elektor International Media, Regus Brentford, Marketing: Carlo van Nistelrooy 1000 Great West Road, Brentford TW8 9HH, England. Editor: Jan Buiting (editor@elektor.com) Tel. (+44) 208 261 4509, fax: (+44) 208 261 4447 www.elektor.com International editorial staff: Harry Baggen, Thijs Beckers, Subscriptions: Elektor International Media, Eduardo Corral, Ernst Krempelsauer, Jens Nickel, Clemens Valens. Regus Brentford, 1000 Great West Road, Brentford TW8 The magazine is available from newsagents, bookshops and 9HH, England. electronics retail outlets, or on subscription. Design staff: Christian Vossen (Head), Tel. (+44) 208 261 4509, fax: (+44) 208 261 4447 Elektor is published 11 times a year with a double issue for July & August. Ton Giesberts, Luc Lemmens, Jan Visser. Internet: www.elektor.com/subs 6 02-2011 elektor
  7. 7. 61002 Elektor PCB Prototyper A professional PCB router E W! with optional extensions! N This compact, professional PCB router can produce complete PCBs quickly and very accurately. This makes the PCB Prototyper an ideal tool for independent developers, electronics labs and educational institutions that need to produce prototype circuits quickly. Specifications • Dimensions: 440 x 350 x 350 mm (W x D x H) The PCB Prototyper puts an end to waiting for boards from • Workspace: 220 x 150 x 40 mm (X x Y x Z) • Weight: approx. 35 kg (78 lbs) a PCB fabricator – you can make your own PCB the same • Supply voltage: 110–240 V AC, 50/60 Hz • Integrated high-speed spindle motor; day and get on with the job. In addition, the PCB Proto- maximum 40,000 rpm (adjustable) typer is able to do much more than just making PCBs. • Integrated dust extraction (vacuum system not included) A variety of extension options are available for other • USB port for connection to PC • Includes user-friendly Windows-based tasks, and a range of accessories is already available. software with integrated PCB software module Ordering The complete machine (including software) is priced at € 3,500 / £3,100 / US $4,900 plus VAT. The shipping charges for UK delivery are £70. Customers in other countries, please enquire at sales@elektor.com. Further information and ordering at www.elektor.com/pcbprototyper Email: subscriptions@elektor.com Email: t.vanhoesel@elektor.com system of any nature. Patent protection may exist in respect of Rates and terms are given on the Subscription Order Form. Internet: www.elektor.com circuits, devices, components etc. described in this magazine. Advertising rates and terms available on request. The Publisher does not accept responsibility for failing to identify Head Office: Elektor International Media b.v. such patent(s) or other protection. The submission of designs or P.O. Box 11 NL-6114-ZG Susteren The Netherlands Copyright Notice articles implies permission to the Publisher to alter the text and Telephone: (+31) 46 4389444, Fax: (+31) 46 4370161 The circuits described in this magazine are for domestic use design, and to use the contents in other Elektor International only. All drawings, photographs, printed circuit board layouts, Media publications and activities. The Publisher cannot guaran- Distribution: programmed integrated circuits, disks, CD-ROMs, software tee to return any material submitted to them. Seymour, 2 East Poultry Street, London EC1A, England carriers and article texts published in our books and magazines Telephone:+44 207 429 4073 (other than third-party advertisements) are copyright Elektor International Media b.v. and may not be reproduced or transmit- Disclaimer UK Advertising: ted in any form or by any means, including photocopying, scan- Prices and descriptions of publication-related items subject to Elektor International Media b.v. ning an recording, in whole or in part without prior written per- change. Errors and omissions excluded. P.O. Box 11 NL-6114-ZG Susteren The Netherlands mission from the Publisher. Such written permission must also be Telephone: (+31) 46 4389444, Fax: (+31) 46 4370161 obtained before any part of this publication is stored in a retrieval © Elektor International Media b.v. 2010 Printed in the Netherlands elektor 02-2011 7 ELEK UK1101 PCB Protoype_p7.inddSec1:7 Sec1:7 30-11-2010 13:38:12
  8. 8. 61002 NEWS & NEW PRODUCTS External 48 & 60 watt the changing energy efficiency legisla- power supply series tion, XP Power provides a number of useful resources and information on their web site. meets latest energy In addition, XP Power applications and sup- standards port staff can assist customers in under- standing the various ‘green’ initiatives. XP Power recently announced the launch of The AFM series is available from Farnell or the highly efficient single output AFM series direct from XP Power. The units have a 3 of 48 & 60 watt external AC-DC power sup- year warranty. plies designed for a wide range of IT and www.xppower.com (100820-IX) medical equipment. The ranges offer out- put voltages of 12, 15, 18 and 24 VDC. Offering a typical efficiency of up to 88%, these highly efficient units meet the lat- Smart current sink LED est stringent energy efficiency standards such as Energy Star Level V, EISA2007 and backlighting platform CEC2008 in the United States and the ErP Semtech Corp. recently announced the Directive for Europe. These standards define industry’s first smart current sink LED back- lighting platform with on-chip digital light- ing effects for high-end handheld displays. This new platform incorporates Semtech’s tem cost, with the added benefits of elimi- patent-pending, smart Automatic Drop- nating any switching noise and extending out Prevention (ADP) technology to enable operating time. a new-generation of high-quality current The SC667 and SC668 are the first current sink drivers that can replace boost convert- sinks to incorporate ADP technology. These ers and charge pumps in high-end hand- devices also integrate a number of functions helds, while providing high-quality display to enable high-end features on portables, backlighting. The new SC667 and SC668 including an ambient light sensing/control current sinks with ADP technology reduce circuit that sets backlight brightness based the total parts count and extend battery on surrounding lighting conditions. A PWM life compared to boost converters or charge dimming interface that incorporates a dig- pumps, and offer far superior illumination ital low-pass filter is also included, provid- quality compared to conventional current ing the capability to perform content-adap- sink drivers. Additionally, on-chip digital tive brightness control (versus ‘always-on’ lighting effects provide the flexibility to illumination). incorporate fade, breathe and blink effects The SC668 provides eight current sinks, without changing the firmware. while the SC667 features seven current the average energy efficiency and the max- White LEDs used in backlighting applica- sinks plus an interrupt request indicator sig- imum no load power consumption. The tions typically have a forward voltage up to nal to tell the host processor when an ambi- AFM45 has a no load power consumption 3.6 V. When the battery voltage declines in ent light threshold has been crossed. Both of less than 0.3 W, and the AFM60 less than portable devices, the supply voltage must devices include an on-chip digital lighting- 0.5 W. be boosted to ensure the white LEDs have effects engine to control LED fade-in/fade- In addition, the AFM series comply with the sufficient voltage to illuminate the display. out, breathe, blink, auto-dim full, and auto- internationally recognized safety approval Charge pump or inductive boost converter dim partial; an I2C interface to program and standards for IT and commercial equip- devices have typically been used to provide control the LEDs; and four programmable, ment IEC60950-1 / UL60950-1 / EN60950- this voltage boost function. In an effort to 200 mA low-noise LDO regulators to man- 1. They also comply with the IEC60601-1 maintain constant output power, these cir- age the power for multiple embedded / UL60601-1 / EN60601-1 medical safety cuits increase current draw as the battery peripherals. standards. voltage declines, shortening battery life. Key Features of the SC667 and SC668 The units offer multiple input cable inter- Improvements in white LEDs have resulted include face options allowing designers to specify in forward voltages as low as 3.0 V, reduc- • Patent-pending Automatic Dropout Pro- either IEC320-C14, -C6 or -C8 connectors. ing the threshold at which conventional tection (ADP) technology The -C8 option provides a Class II grounding LED drivers need to boost the battery volt- • On-chip digital lighting effects (fade, method. An optional cable restraining clip age. Because of this, LED backlight driv- breathe, blink) without changing is also available. ers increasingly are operating in a non- firmware XP Power is an Energy Star partner and boost mode, making current sink drivers • Ambient light sensing option can auto- has an approved certification facility that an attractive alternative. Current sink driv- matically adjust backlight brightness allows in-house testing for compliance to ers eliminate the capacitors and inductor • Low parts-count: only one low-voltage the energy efficiency standards. associated with the boost circuitry, reduc- capacitor needed, no inductor required To help designers keep up to date with ing component count, board size and sys- • I2C programming interface (fast and 8 01-2011 elektor
  9. 9. 61002 standard modes) Frequency stabilities can be specified at • ±0.5% (typ.) LED current matching, ±1.5% either ±10 ppm over an operating tempera- (typ.) LED current accuracy ture range of 0 to +70 degrees C or ±15 ppm • Four low-noise LDO regulators over –40 to +85 degrees C. • Ultra-small, low-profile 20-pad MLPQ MEMS technology is based upon the pro- package with exposed thermal pad: 3 x cess techniques of CMOS (Complemen- 3 x 0.6 mm tary Metal Oxide Silicon) and as such can be produced on standard production lines The SC667 and SC668 are available imme- in foundries that are more used to produc- diately in production quantities. ing standard or custom integrated circuits. www.semtech.com (100820-X) This of course lends itself to the ability of producing product in vast quantities at an tor is available in an exceptionally wide fre- economic rate. quency range from 1MHz up to 800MHz. The IQMS-900 range is eminently suitable MEMS oscillator covers The new model can be factory programmed for the incorporation into infrastructure with either a LVDS (low voltage differential equipment where it will provide very accu- 1 MHz to 800 MHz source) or LVPECL (low voltage positive rate timing processes coupled with the abil- frequency range emitter coupled logic) output. ity to drive the very latest high-speed pro- The plastic packaged IQMS-900 series is cessors that will enable the transfer of high IQD has announced immediate availability available in two sizes: either a 7 x 5mm or data rates — the fast rise and fall times con- of a newly developed high frequency MEMS the increasingly popular 5 x 3.2mm. Due to tribute to this. Typical applications include Oscillator on the opening day of Electron- its MEMS technology design, phase jitter is Fibre Channel, Ethernet 10G, HDMI, SATA/ ica 2010. The new IQMS-900 series MEMS low being typically 0.7 ps at 200 MHz. Two SAS & USB3. (Micro Electro Mechanical Systems) oscilla- supply voltages are available, 3.3 V & 2.5 V. www.iqdfrequencyproducts.com (100820-XI) Advertisement elektor 01-2011 9
  10. 10. 61002 NEWS & NEW PRODUCTS Factory modification medical instrumentation. means that it can be installed in the most services for enclosure Card mounting brackets, conductive and compact of applications. non-conductive fixings, handles, gaskets TDK-Lambda’s ZPSA100 series is approved panels and sealing strips can all be supplied to to national and international safety approv- Standard front panels for enclosures and meet specific project requirements. als, including IEC/EN/UL/CSA60950-1 (edi- sub racks, typically conforming to sizes www.verotl.com (100820-XII) tion 2) meets conducted and radiated EMC specified in international standards, are requirements of EN55022-B and FCC Class produced by many companies, giving B (without additional filtering or compo- users ready availability and a wide choice nents) and meets EN61000-4 immunity of suppliers. All such panels have one thing 100-watt low profile specifications for greater reliability. All mod- in common; they will usually need to be els in the ZPSA100 series carry the CE mark, modified to suit the application before PCB-mountable power according to the LV Directive, and come they can be used. Vero Technologies offer supplies with a two-year warranty. a rapid turn-round factory customisation www.uk.tdk-lambda.com/zpsa (100820-XIII) service for its own manufactured panels, a Power supply expert T D K- L a m b d a France has upped the output power of its ZPSA series of compact PCB-mountable AC-DC power supplies with the introduc- WLCSP 2.4 GHz chips tion of a 100 watt model. The new single- output ZPSA100 accepts a wide input volt- target space-constrained age range, has a very low profile (26.6mm) sports, fitness, and health and industry standard footprint (127 x 76.2 mm), making it an ideal choice for applications applications such as LED signage and light- Ultra low power (ULP) RF specialist Nordic ing, point-of-sale equipment, datacom, Semiconductor ASA (OSE: NOD) recently video/audio routers and test & measure- announced that it is to expand its exist- ment equipment. ing 2.4 GHz RF and ANT™ product line- These 100-Watt supplies are available with ups in Q1 2011 with a new set of ultra the most popular single output voltages miniaturized, wafer-level chip scale pack- from 5V to 48Vdc. Offering a typical effi- age (WLCSP) options designed to meet ciency of up to 90%, these models are well- the highly space-constrained needs of suited for operation in both convection or both existing and emerging sports, fitness customer air cooled environments from and health applications such as wireless 0°C up to 70°C, with appropriate derating. watches, bike computers, sensors, hearing A green LED is provided as an indicator that aids and other devices designed to be worn the power supply is on, and other standard features include over voltage and short-cir- cuit protection. These supplies are offered modification service for panels from other in an open-board configuration with Molex suppliers and bespoke panel fabrication to input/output connectors. customer drawings with a maximum size of Accepting a wide input voltage range of 480 x 400 mm. 90-264 VAC (47–440 Hz) or 120–370 VDC, Panels can be punched, drilled, multi-colour the ZPSA100 series is ready for use globally screen-printed, engraved, engraved with a with no further configuration or input selec- coloured infill, fitted with polyester over- tion. Its industry standard footprint makes lays, rebated to accept a flush-fitting mem- it an ideal choice as a drop-in replacement brane keypad and fitted with EMC gaskets. for existing supplies, while its low profile Conductive and non-conductive finishes, to both sides or just to the rear can be pro- vided or the panels can be painted. Cutouts on or near the body. can be within 1mm from the panel edge Sampling in Q1 2011 and available for vol- without distortion by using laser machin- ume orders in Q2 2011 will be the nRF24AP- ing or extend through the edge by using 2WLCSP (1- and 8-channel) and nRF24LE1 three-dimensional CNC machining, ena- WLCSP (Flash or OTP) options. bling rebates and apertures to be created. The new 1- and 8-channel nRF24AP2 WLCSP Both plastic and metal panels can be modi- package options will represent the world’s fied; plastic panels and enclosures can be small single chip ANT solutions (nRF24AP2- moulded in custom colours. Specialist fin- 1CHC32 and nRF24AP2-8CHC32) featuring ishes can be applied to give EMC/RFI pro- 400μm pitch (regular array) 32-ball BGAs tection or anti-bacterial capability for use in with a thickness of 0.5 mm and a flat foot- 10 01-2011 elektor
  11. 11. 61002 NEWS & NEW PRODUCTS print area of just 2.6 x 2.7mm (7 mm2) that of workers with constant exposure. An moving through the doorway, ADAM will is over 5x smaller than the footprints of enhanced audio system that could gener- automatically revert to playing the original competing 6 x 6 mm (36 mm2) packaged ate a variety of sounds and automatically song. products. associate these sounds with vehicle position ADAM RAP also has the ability to react to The new nRF24LE1 WLCSP option (Flash or or function would dramatically improve the inputs. As another example, if a worker (or OTP) will again be a 400μm (regular array) effectiveness of the warning system. object) is fully obstructing the doorway and 32-ball pitch BGA measuring 2.7 x 2.7 RMT Robotics developed the ADAM sound ADAM is unable to reconcile an alternative (7.3 mm2) in footprint area for the Flash ver- application to play ‘text to speech’ mes- path, ADAM will politely enunciate, “Please sion and 2.6 x 2.7 (7 mm2) for the OTP ver- sages, sound bites or musical interludes move, I cannot get around you.” As another sion. Both devices are 0.5 mm in thickness. through its mobile robot that can be either example, if the emergency stop button is www.nordicsemi.no (100926-I) actively or passively triggered in reaction pressed, ADAM will state, “My emergency to a variety of operational conditions and stop has been pressed,” or if the Enter Desti- system inputs. Through the ADAM Com- nation button is pressed on the vehicle key- mander mapping software, regions on pad, ADAM will state, “Thank you, see you RAP for ADAM mobile later” before proceeding on its mission. “Now that ADAM can “speak” and interact robot with workers, there is an improved harmo- RMT Robotics ® a Cimcorp Oy company, nization between the work force and the launches ADAM RAP (Reactive Audio Play- robots that serve them,” says Torrens. “The back). The programmable sound system, fact that ADAM can also entertain while designed exclusively for the RMT Robotics enhancing safety and efficiency in the pro- ADAM (Autonomous Delivery and Manip- cess is an added bonus.” ulation) mobile robot, includes interac- www.rmtrobotics.com (100926-II) tive voice messages and a mobile “vehicle in motion” jukebox for every mood and season. “In developing the ADAM RAP module, we Contactless sensing wanted to create a new ‘vehicle in motion’ function that not only improves safety but for 360° navigation leverages the power of the ADAM plat- in human-machine form to enhance the interactive experience between humans and the mobile robots interfaces that they work with every day,” said Bill Tor- austriamicrosystems has announced the rens, Director of Sales & Marketing for RMT the facility map can be embedded with AS5013, a contactless magnetic encoder Robotics. commands to automatically load specific IC that monitors the displacement of a AGVs have a standard beeper-based ‘vehicle tunes or prompt a series of voice mes- magnet incorporated in a knob relative in motion’ alert system which is mandated sages. For example, ADAM may play a song to its centre position and provides x and by most international safety standards. In in the aisle ways and then switch to a text y position information via an I²C interface. most operations however, noise prolifera- to speech-based message saying, “Excuse The AS5013 Hall-sensor IC is used in the tion combined with the monotonous beep me I am coming through” as it approaches EasyPoint(TM) module, which consists of a of vehicles tends to diminish the alertness the region of a doorway. After successfully mechanical stack incorporating a naviga- Advertisement elektor 01-2011 11
  12. 12. 61002 NEWS & NEW PRODUCTS iPad app for Engineers gineers Apple brought a whole new format to the world of personal com- puting when they intro- duced the iPad. The handy tablet computer can be taken anywhere and the interactive touch screen makes it dead easy y to use. Add to that the e convenience of the thou- - sands of downloadable e software apps available e to solve real-world prob- b- lems the iPad can be with- h- bridge), high and low pass filters (R/C, R/L and L/C) and an ool. out doubt a very useful tool. transistor circuits (with base resistor values and voltage divider b Elektor have added another to the firmament of apps with their calculations). The ubiquitous NE555 is also included as a basic ‘Elektor Electronic Toolbox’. This one should be indispensable to circuit building block as are all the characteristics of the differ- engineers and hobbyists alike. It comprises 28 applications, any ent colour LEDs. one of which can be selected from the opening screen. The electronic toolbox not only provides assistance in component The app contains a data bank of over 45,000 electronic compo- selection but also supports some engineering design activities. nents, including bipolar transistors, FETs, triacs, thyristors, diodes For example circuits often require a regulated DC linear power and ICs. A component can be selected from the lists in different supply and this app has all the tools necessary to make the job categories on the left hand side of the display. As usual for iPad a cinch. you can drag your finger to scroll through the list and select a Other useful tools include a virtual resistor colour-code clock, component by tapping the screen whereupon the pin-outs and units of measurement converter, circuit diagram symbol data important electrical characteristics appear on the right side of the bank plus much more. display. All data is contained in the app so an internet connection The Elektor Electronic Toolbox can be downloaded from the Apple is not necessary. Also included is a special data bank containing iTunes Store for just $4.99. Go to the apps web page for more pin assignments of the majority of connectors used in the fields information. of audio, video, computer and telephone engineering. To add to that an interactive component calculator is included UK & European readers: http://apps.elektor.com/Toolbox/?c=en&d=3&l=en which simplifies the design of resistive circuits (series, parallel, US & Canada readers: http://apps.elektor.com/Toolbox/?c=us&d=3&l=en tion knob, a magnet and the AS5013 mag- coordinate and motion detection engine, face to the host processor. netic encoder IC. Its simple construction and a smart power management control- The HMI device also provides two interrupt and contactless sensing technology give ler. The XY coordinate registers and mag- modes (motion detect, data ready) and two the module very high reliability and operating modes: idle mode, with is designed for any kind of 360° navi- less than 3 μA current consumption, gation input device. and low-power mode, with selecta- The AS5013 is a complete Hall-sensor ble readout rate. The low-power IC for human-machine interface (HMI) AS5013 operates over a power sup- applications requiring low power. This ply range of 2.7 to 3.6 V, and down to simplifies software integration chal- 1.7 V peripheral supply voltage. lenges for joystick navigation in prod- Specified over an operating temper- ucts such as cell phones and other ature of –20 to +80°C, the AS5013 handheld devices, e.g. MP3 players, Hall-sensor IC operates from a 3.3 V PDAs, GPS receivers, Digital Still Cam- power supply and is offered in a eras, gaming consoles, and remote 16-pin 4 x 4 x 0.55 mm QFN package. controls. The AS5013 single-chip IC The EasyPoint(TM) module is available includes user-selectable power-sav- as small as 8 x 8 x 1.5 mm. ing modes, 5 integrated Hall sensing elements for detecting up to ±2 mm www.austriamicrosystems.com/ lateral displacement, a high-resolution netic field information for each Hall-sensor AS5013/Hall-sensor-IC analogue-to-digital converter (ADC), an XY element are transmitted over the I²C inter- (100926-VI) 12 01-2011 elektor
  13. 13. 61002
  14. 14. 61002 COMPUTERS OSI from ISO Seven layers is all it takes As with any structured approach to such would be concerned with details of the This gives rise to a functional hierarchy of a problem it would be best to identify and physical transfer of bits over the medium the program structure which Elektor edito- divide the job into manageable tasks. Pro- while other higher level tasks would deal rial team have chosen to illustrate using this cesses to deal with error control and data with the interface to the application soft- seven-layered cake. packet addressing for example can be eas- ware. In between the data would pass Now we come to the International Organi- ily defined. Some of the lower level tasks through a series of intermediate processes. zation for Standardization (ISO) which as 1 Physical Radio, optical or cabled, it doesn’t matter which medium you edium y use, this layer defines how a digital 0 and 1 is represented in ented munic the media so that transmitter and receiver can communicate with one another. 2 Data link This layer is responsible for detecting corruption of the trans- ion mitted message. The interference may come from an external source or from more than one transmitter talking at the sam t same es d time on the network (data collision). Techniques such as data packetisation, message headers, checksums and CRC algo- rithms all help here. 3 Network This layer ensures that each packet arrives at the correct re- he ceiver. In larger networks there may be a hierarchy of networ y network nodes relaying the data packets. Similar to how a postal ad- dress and code uniquely identifies a delivery address, the des- e s tination address is comprised of several fields e.g. a series of characters or character sequence. 14 02-2011 elektor
  15. 15. 61002 COMPUTERS When computers communicate it’s important that messages are exchanged reliably, efficiently and securely (to protect against eavesdropping). To build such a complex communication protocol from scratch represents more than a weekend’s work for sure. usual has a thing or two to say about techni- faces are strictly adhered to (i.e. the func- building blocks which can simply be linked cal standards. At the beginning of the 1980s tion of each layer and the data between the to fulfil a particular communication require- they released the OSI layered model (Open layers) it is possible to substitute a layer from ment. A similar model called TCP/IP uses Systems Interconnection Model) which sub- one implementation of the standard model fewer layers and is responsible for data trans- divides such a communication system into to another without problem. This promotes fers most notably over the internet. seven distinct ‘layers’. When all the inter- the concept of interchangeable software (100781) 4 5 Transport Session This layer checks that all the packets have arrived correctly. d This layer ensures that a ‘discussion’ between the transmitter Packets can be dropped when net nodes are overloaded. A verloaded. and receiver can be successfully concluded, even if the ses- ven tected. resend request can be issued if an error is detected. The basic sion is interrupted. When interruption occurs (for whatever n requirement is that communication occurs in both directions. reason) it ensures that the exchange does not need to start ion Protocols such as TCP build a logical connection between the from the beginning again. transmitter and receiver. Presentation 6 This layer deals with the details of formatting and encrypting data for transmission over the network. g 7 Application This layer forms the interface between the user software and re ansfer, the network providing application facilities for file transfer, s email and other network services. Protocols such as HTTP and a fer emai SMTP, used by the World Wide Web (e.g. to transfer emails) are implemented in this layer. elektor 02-2011 15
  16. 16. 61002 MINI PROJECT Reradiating GPS Antenna Banish poor reception in cars By Ton Giesberts (Elektor Lab Labs) bs) A portable navigati system often suffers navigation s ion from poor reception wh used inside a car. n when hen This can easily be improved with the help of an imp prove proved active antenna and the mini circuit described here, which doubles as the battery charger. The signal strength of a portable navigation while we have one of those, we could, at the from a sturdy piece of enamelled copper system such as a TomTom, a Garmin eTrex same time, also use it to charge/power the wire soldered to the prototyping board on or a PDA/mobile phone with built-in GPS- navigation system or PDA while in the car. which the remainder of the circuit is built. receiver is often poor inside a car because of The circuit is so small that all of it is easily The wire is 19 cm long, equal to the GPS the metal coating which is often applied to accommodated on a small piece of proto- signal’s wavelength. It is normally recom- the windscreen of a modern car. A possible typing board of a few square centimetres. mended to keep the loop between 1/8 solution is an active, external antenna. This and 1/4 of the wavelength to prevent self type of antenna is available in all sorts of The circuit basically consists of a standard resonance. But with a larger dimension it shapes and sizes. However, many portable application for the LM317 voltage regulator is easier to bend it into a shape that suits GPS-receivers do not have a connection for (C3 for less noise and higher ripple/interfer- the GPS receiver better (the loop has to be an external antenna (any more); PDAs are ence suppression) and a pass-through cir- positioned near the location of the internal not all that likely to have one either. cuit for the signal from the active antenna antenna). to the antenna which will be mounted near In order to provide a navigation system the navigation system. A loop antenna is The power supply for the active antenna is without an external antenna connection used for the radiating element. This is made first RF decoupled with R4 and C5/C6. R4 is with a stronger satellite signal, it is possible to use a so-called re-radiating antenna. A loop antenna is installed either in, behind, or IC1 in front of the navigation system (depend- K2 F1 LM317 ing on the position of the receiving antenna 3 2 inside the navigation system) which then re- 0A5 adj 5V C8 radiates the received and amplified GPS sig- S1 R1 1 R2 R4 0 K1 100n 270R nal from an active antenna mounted on the 3k3 1R C1 C2 C4 outside of the car. In this way the navigation K3 L1 Active system is still able to receive a sufficiently 1u 100n 1u antenna 63V 63V large signal so that it can function properly. +12...14V R3 D1 C3 C5 C6 C7 820R 10u 1n 100p 100p For this design we only need a commer- 63V cial active GPS antenna and a tuned cir- cuit which will re-radiate the output signal 100808 - 11 that is available on the connector at the end of the active antenna cable. In addi- tion, we require a regulated power supply Figure 1. The schematic for the circuit: a voltage regulator and an antenna circuit which for powering the active GPS antenna. And re-radiates the GPS signal from an active antenna. 16 02-2011 elektor
  17. 17. 61002 Advertisement AFFORDABLE EXPERTISE THE PC OSCILLOSCOPE RANGE FROM PICO TECHNOLOGY a normal, through-hole resistor which is mainly used as an induc- tor. By keeping the value of R4 low, the voltage drop across it is kept as small as possible. L1 decouples the active antenna signal from the power supply voltage. L1 is an air-cored coil, made by wind- BANDWIDTH ing a few turns (6 or so) around a small diameter drill bit (diameter 20 MHz to 12 GHz 5 mm). Keep the individual turns apart by at least the thickness of the wire used (for example 0.5 mm CuL). This is to minimise the internal capacitance. A standard 100-pF-capacitor is used to cou- SAMPLING RATES ple the signal from the active antenna to the loop antenna. None 50 MS/s to 5 GS/s of this is very critical. The photo shows the assembled prototype. The circuit was MEMORY found to work superbly. We have tested it within the thick walls 8 kS to 1 GS of our castle with, among others, a Pocket PC Mio P350. This had no reception inside the building, but by placing it next to the loop antenna it was able to find six satellites quite quickly. RESOLUTION The active antenna was placed near a window. The 5-V voltage on K2 can be used as the power supply for the Pocket PC (or GPS 8 to 16 bits receiver or some other device with GPS functionality). This is often a mini-USB connector which is also intended for charging PRICES the battery. Fuse F1 is there for safety, so that when experiment- ing you will not easily blow one of the car’s fuses. In our proto- £125 to £6995 type, the power consumption (without load on K2) amounted to just below 28 mA. Latest Software Updates: I²C & CAN bus decoding, There appears to be no standard for the connector at he end of the mask limit testing, advanced triggers, cable of the active antenna. The same antenna is often available digital low pass filtering, rapid triggering with different types of connectors. For testing we used an older type made by Trimble (39265-50) which has 5 meters of cable and an MCX connector. There are also active antennas with SMA, SMB, etc. So before you buy an active antenna, check that you can also obtain the corresponding chassis-mount connector. www.picotech.com/scope203 (100808-I) elektor 02-2011 17
  18. 18. 61002 HOME & GARDEN Gentle Awakenings Programmed sunrise By Aike Terjung (Germany) In the natural world, our biological clocks are controlled by daylight. The light alarm clock described here imitates a natural sunrise to wake you gently from your slumbers in a natural manner. Start your day better by waking to the light instead of that horrid alarm clock. We all know the unpleasant to what happens at sunrise, and in feeling of being rudely awak- Features any case it is more attractive than ened from our sleep by the • Output connector for one or more dimmable 230 V / 115 V what you see with an LED dimmed buzzing, beeping or ringing lamps (80 W max.) under PWM control. If you wanted of an alarm clock. This often • DCF77 radio time synchronisation to simulate this effect with LEDs, happens when you’re in deep you would have to use RGB LEDs • Touch sensor for switching off the alarm sleep, which frequently results or LEDs with several different col- • ATmega168 microcontroller in not feeling properly awake ours. Things would be even more or groggy the whole day long. • PCB and programmed microcontroller available from Elektor complicated if you also wanted to However, it doesn’t have to • Firmware and source code available free from Elektor be able to continuously vary the be this way. If you sleep in • Can also be used on 115 V power grids brightness. The power savings that the summer with the win- could be achieved by using LEDs dows unobstructed, you often are anyhow very limited because awaken spontaneously when it becomes fitted with an incandescent bulb (normal or the alarm clock does not keep the lamp lit light outside. halogen). Although it might seem more log- for hours on end. When you awaken in this natural, gentle ical to use power LEDs, there are good rea- In addition to a lamp, the light alarm clock manner, you also feel much better, and this sons for using an incandescent lamp. Aside naturally needs to know what time it is. A feeling often persists all day. Obviously, from low cost (money and effort) and the DCF77 receiver module is a good solution it would be better to start your day with possibility of using a lamp you already have here, since it allows us to use a fairly sim- a simulated sunrise if the real thing isn’t on hand (such as a bedside lamp), the col- ple, software-controlled time base in the available. our characteristics of incandescent lamps microcontroller. There’s no need for a real- are better for this purpose. The colour of time clock, since the microcontroller clock Light and time the light from an incandescent lamp var- frequency (controlled by an external quartz The light alarm clock described here is built ies when it is dimmed, gradually changing crystal) is sufficiently accurate to allow it to around a microcontroller and can switch from a strong red hue to nearly white as manage for several hours without a proper and dim an existing 230-V lamp (or lamps) the brightness is increased. This is similar DCF77 radio signal. 18 02-2011 elektor

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