www.elektor-magazine.com

magazine

November 2012

r

Test, Repair, Analyze, Map, Simulate & Unravel Your Rolling Network

Linux Board Mk. 2

LCR Meter V 3.0

Multichannel Temperature Logger

USB Thermometer | Bidirectional 4-Channel Audio Selector | LED Lighting

for Model Buildings Standards for Coding

FPGA

US $9.00 - Canada $10.00

Pins Afloat | PCB Milling Master Class • 1935 Audio Spectrometer

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ARDUINO UNO

The most popular board with
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Features

■

Micro cun (roller

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Operating Voltage

5V

Input Voltage

7-12V

(recommended)

Input Voltage (limits)

6-20V

Digital 1/0 Pins

14 (of which 6 provide

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PWM Channels

6

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6

DC Current per I/O Pin

40 mA

DC Current for 3.3V Pm

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Rash Memory

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Features

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6-20V

Digital I/O Pins

20 (of which 7 provide PWM

output)

PWM Channels

7

Analog Input Pins

12

DC Currenl per I/O Pin

40 mA

DC Current for 3.3V Pin

50 mA

Flash Memory

32 KB fol Which 4 KB used

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SRAM

2.5 KB

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Clock Speed

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ARDUINO

@ektor

FeaJiar-es
Microcontroller
Operating Voltage
Input Voltage
{recommended)

Input Voltage (limits)
Digital I/O Pins

Arduino Pins reserved

Analog Input Pins
CG Current per I/O Pin
DC Cur rent for 3.3 V Pin
Flash Memory

SRAM
EEPRCM
Cluck Speed

ATmega32B

5V

7-1 2V
6-2QV

14 (of which 4 provide PWM
output)

10 to 13 used forSPI
4 used tor SD card

2 W51 00 Interrupt (when
bridged}

6

■10 mA
50 mA

3? KB [of which 0 5 KG used
by bootloader}

3 KB
1 KB
16 MHz

Features
Microcontroller
Operating Voltage
Input Voltage
[recommended)

Input Voltage (limits)
Digital I/O Pins

Analog Input Pins
DC Current per I/O Pin
DC Current lor 3.3V Pin
Flash Memory

SPAM
£ EPROM
Clock Speed

ATrnega?56Q

5V

7-1 2 V
6-20V

54 {ol which 15 provide
PWM output)

16

40 mA
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256 KB (of Which 3 KB used
by haul loader)

S KB
4 KB
16 MHz

lit

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Features
Micro corn ru Iter
Operating Voltage
Input Voltage
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input Voltage (limits)
Digital I/O Pins

PWM Channels
Analog Input Pins
Analog Outputs Pins
DC Current per I/O Pin
DC Current for 3.3V Pin
DC Current tor 5V Pin
Flash Memory

SRAM

Clock Speed

AT91SAM3XBE

3.3V

7-1 2V

6-20V

54 (of which 12 provide PWM
output}

12

12

2 (DAC)

130 mA
600 mA
800 mA

512 KB (all available Tgr Ihe
user applications 1
96 KB (two banks: G4KB and
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Contents

• Community

8 Elektor World

* Let Your Brain Do the Thinking

* All Smiles

• The Internet of Things' Launching Point

• That Sounds Good!

• Projects

10 CAN Tester

The circuit described here has all the
features required for conducting various
experiments and tests on a CAN bus. In
addition there is the option of connecting
the tester to an existing CAN bus to mon-
itor the data or to track down faults,

18 Elektor Linux Board:

New and Improved!

The compact and low-cost Elektor Em-
bedded Linux board has been available

to buy for around a year and a half now.
Along with its accompanying series of
articles it offers even beginners access to
the world of embedded Linux, It is now
time for us to update the board based on
feedback from the user community. To
begin with let's add LAN and RTC

22 Important Update to the
Elektor 500 ppm ICR Meter

Here we correct two shortcomings liable
to interfere with proper operation of the
instrument: occasional hang-ups and
issues with the Trim actions.

26 Multichannel

Temperature Logger

This project allows you to log up to six
temperature readings over a period of
time, complete with time stamps, al!
written to a ,csv file stored on an SD card
for processing on a PC, Local control is
also available in the form of an LCD and
a keypad,

32 USB Thermometer

When you need to hook up some elec-
tronics to an RS-232-less computer, the

USB port looks like the only option. The
computer however needs a correspond-
ing software driver. Here we describe an
elegant patch around this problem.

42 Bidirectional

Stereo Input Selector

Following a recent appeal made in the
magazine calling on our readers to send
us their own circuit designs— if possible
simple and preferably in fields that re-
ceive less coverage in Elektor, like audio,
for example—we received this suggestion
which meets the two main criteria: un-
complicated and intended for processing
sound signals,

46 LED Lighting

for Model Buildings

This small module has been designed
to individually control five LEDs used to
illuminate model buildings. The control
signal is sent over a single wire from a
PCs RS232 serial port. The design allows
for up to 250 modules to be controlled by
a single PC, that's almost enough for a
small town!

4 | November 2013 | www.elektor-magazine.com

Volume 39

No. 443

November 2013

t>BWT

• DesignSpark

38 DesignSpark Tip & Tricks,

Day #5: generating
PCB manufacturing files
Today we will generate the Gerber files
and BOM information for the design we
laid out last time. DesignSpark has excel-
lent support for generating these types of
files once it's been configured properly.

Labs

50 .Labs Tips & Tricks

This month we present a selection of
projects posted on Elektor.Labs and look-
ing for a helping hand to reach the finish
line. Can you cheer and/or assist?

52 Standards for Coding

Often a lot of time and energy is spent on
designing an elegant, well-thought-out
and robust circuit Today, the brains of
many of those circuits is a microcontrol-
ler that needs software to function. Is it

unreasonable then to expect a well-de-
signed, properly written program to
make such a quality circuit work? Appar-
ently it is. Let's talk software quality.

58 Keep The Pins Afloat

Forget to tick a few boxes and your entire
FPGA project fails to work, as our lab
workers Found out the hard way.

60 PCB Prototyper Master Class

Here's a how-to on an advanced applica-
tion of the Flektor PCB Prototyper milling
machine.

Tech The Future

68 Forze VI:

A Hydrogen-Powered Racecar

The Forze VI weighs just under 2,000
lbs., achieves a top speed of 138 mph,
and accelerates from 0 to 60 mph in 4
seconds. The heart of the racecar is the
fuel ceil system.

• Industry

64 News & New Products

A selection of news Items received from
the electronics industry, labs and orga-
nizations.

• Magazine

70 Retronics: Freystedt's Audio-
Frequency Spectrometer

The story of finding and restoring the ex-
tremely rare 1935 Siemens Spectrometer,
a landmark in electro-acoustic measure-
ment. Series Editor: Jan Buitlng.

76 Hexadoku

Elektor's monthly puzzle.

77 Gerard's Columns:
Conscientious Objector

A column or two from our columnist
Gerard Fonte.

82 Next Month in Elektor

www.elektor-magazine.com | November 2013 1 5

Community

Volume 39, No, 443
November 2013

ISSN 1947-3753 (USA / Canada d stribution)

ISSN 1757-0875 (UK / ROW distribution)

www.elektor.com

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double issues in january/February and July/August, concur-
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Phone: +31 6 15894245
E-mail: j.dijk@elektor.com

www. el e kto r, com /a d ve rtisi ng

Advertising rates and terms available on request,

Copyright Notice

The circuits described in this magazine are for domestic and edu -
cational use only. AH drawings, photographs, printed circuit board
layouts, programmed Integrated circuits, disks, CD-ROMs, DVDs,
software carriers, ar.d article texts published in cur books and
magazines (other than third-party advertisements) are copyright
Elektor International Media b.v. arid may not be reproduced or
transmitted in any form or by any means, Including photocopy-
'll scam ng and recording, n whole or n part without prior
written permission from the Publisher. Suer written permission
must also be obtained before any part of this publication is stored
n a retrieval system ol any nature. Patent protection may exist
n respect of c rcults, devices, components etc. described n this
magazine. The Publisher does not accept responsibility for Fari-
ng to identify such patent(s) or other protection. The Publisher
disclaims any responsibility for the safe and proper function of
reader-assembled projects based upon or from schematics,
descriptions or information published In or in relation with EFek-
tor magazine,

© Elektor International Media b.v., 2013

Printed in the USA Printed in the Netherlands

Can the CAN

Not so long ago you'd be greeted by rust, holes,
grime, goo, mushrooms or mice droppings when
removing a panel or a cover from a broken down
car in order to get access to "the electrics".

Today you are bound to encounter electronics
of the black box or disposable type. Removing
rust or corrosion is a tough but rewarding job
that actually helps to get the car on the road
again. By contrast, remove any piece of reasonably advanced electronics from a
post 2000 vehicle and you may be unable to even switch on the ignition. In-
vehicle electronic systems like OBD, ECU and CAN require a total change of mind
In terms of repair and maintenance work. There's no denying that these systems
are hugely successful and the way forward, but bear in mind that cars with zero-
electronics-on-board-except-the-radio are increasingly popular too.

The best way to explore the route and workings of a bus is to buy a ticket for a
round trip and be kind to the driver. In this edition we present a tool that should
help to remove any fears of addressing issues in vehicles that appear related to
the CAN bus (if fitted! ). The tool is not just analytic, but educational too as it
allows a good deal of messages from CAN devices to be simulated in the comfort
of your electronics lab, as opposed to a garage outfit with Orange County Chop-
pers on the floor and Lady Gaga on the radio. The actual function of the CAN
Tester board is one of about a dozen as determined by the firmware It is running.
This month we are again honoring your requests for projects related to measure-
merit. In this case it's temperature all round with our Multichannel Temperature
Logger (page 26) and the USB Thermometer (page 32). The first reads up to six
sensors and writes ,csv files into a spreadsheet— the second has one sensor and
writes directly to the PC over a USB link.

Besides CAN and temperature measurement the pages ahead present audio,
embedded Linux, PCB milling, Modeling, Coding, racing on hydrogen power,
restoring a 1935 spectrometer and a hex-coded puzzle challenge. I wonder if that
260 HP Forze VI on page 68 has CAN controlled brakes? Or a radio?

Enjoy reading this edition of Elektor,

Jan Suiting, Editor-in-Chief

The Team

Editor-in-Chief:
Associate Editor:
Publisher / President:
Membership Managers:

Jan Suiting
Thijs Beckers
Hugo Van haecke

Shannon Barraclough (USA / Canada),
Raoul Morreau (UK / ROW)

International Editorial Staff: Harry Baggen, Eduardo Corral, Wisse Hettinga,

Denis Meyer, Jens Nickel

Laboratory Staff: Ton Giesberts, Luc Lemmens, Tim Uiterwijk,

Clemens Valens, Jan Visser

Graphic Design & Prepress: Giel Do Is, Jeanine Opreij, Mart Schroijen
Online Manager: Danielle Mertens

Managing Director: Don Akkermans

6 November 2013 www.elektor-magazine.com

Our Network

USA

Hugo Van haecke
+1 360-239-0800
h . va n h aec k e pelektor. c o m

United Kingdom

Don Ak karma ns
+31 46 4389444
w. h etti nga @ e I e ktor. com

H Germany

Ferdinand te Walvaart
+49 241 88 9D9-17
f , tewa I ve a rt@e I ekto r. de

France

Denis Meyer

4 31 46 4339*35

d, meyer@elektor.fr

Netherlands

Erik Jansen
+31 45 4333429
h . b a ggen @elekto r nl

Spain

Eduardo Corral
+ 34 91 101 93 95
excrralpelekror.es

U

ga

Italy

Maurizio del Carso
+ 39 2.56504755
m . delcorsc @ i n wa re . i L

Sweden

Don Akkermans
+ 31 46 4389444
w. h etti nga @ e l e ktor. com

Brazil

Joao Martins
+ 31 46 4389444
j . ma rtfns@ el e kto r. com

Portugal

Joao Martins

+ 31 45 4389444

j . ma rti ns@ el e kto r. com

India

Sunil D. Malekar
+91 9833166815
ts@elektor.ln

Russia

Nataliya Melnikova

+ 7 (965) 395 33 3b

F I e <to r. Ru ssia @gma i I . com

Turkey

Zeynep Koksal
+90 532 277 48 26
zkoksal@teti.com »tr

South Africa

Johan Dijk
+ 31 6 1589 4245
j.dij k@elektor.com

China

Cees Baay

+85 21 644,5 281 1

Cees Baay @gma 1 1 . com

Connects You To

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Not a supporting company yet?

Contact Peter Wostrel (peter@smmarketing.us, Phone 1 978 281 7708,
to reserve your own space in Elektor Magazine, Elektor«POST or Elektor.com

www.elektor-magazine.com November 2013 7

Community

Compiled by

Wisse Hettinga

Elektor World

Every day, every hour, every minute, at every
given moment designers and enthusiasts are
thinking up, tweaking, reverse-engineering
and developing new electronics. Chiefly for fun,
but occasionally fun turns into serious business.

Elektor World connects some of these events and activi-
ties — for fun and business.

Let Your Brain Do The Thinking

...and the software do the work. Here at the MOSI (Museum of Science
and Industry) in Manchester, UK, a group of 20 designers from a selection
of companies rally to take the new DesignSpark Mechanics to the limits.
The challenge is to develop something life saving' in 48 hours and
have it 3D printed! Not an easy task for people who are normally doing
many things besides saving the globe, but the ideas that come up are
interesting. Currently it's fair to say that the Elektor team's world-saving
activities are limited to preventing a few hapless plants from drying out
in their office-mt's a start.

All Smiles

The guys you see smiling are on
the the Flowcode designers 1 team,
They have every reason to be
happy, just having finished Flow-
code version 6, a new and excit-

ing product.

Where other coding programs let you see a blinking LED or a signal level, Flowcode 6 allows you
to program and simulate a complete 3D world. Typical 3 D CAD program designs can be imported
and brought to life. For example, you can have your 3D printer design first simulate and operate
before you start the actual production. In this way this new version of Flowcode is bridging the gap
between electronics programming and simulation of real world actions.

The team is based in Halifax, UK and I am sure we can expect more applications and developments
from them in the near future.

Flowcode is available in the Elektor Store, see www.elektor.com/flowcode

8 November 2013 www.elektor-magazifie.com

A!! Around the World ...

The 'Internet of Things' Launching Point

It's a bold but not implausible idea that someday many everyday devices w!3!
have embedded sensors that enable them to communicate via an Internet-like
structure. Consumer products from cars to household appliances and other elec-
tronics would be able to connect through such local and global networks. The impli-
cations for individuals and business models are enormous.

According to the marketing firm ABI Research, more than 30
billion devices will be connected wirelessly through the so-called
Internet of Things (loT) by 2020. And Circuit Cellar magazine
has compiled a list of online resources to help individuals and
businesses keep up with the evolution of the loT.

Whether you're looking for a workshop in Italy on wireless sensor
networks, contact information for innovators in the field, or details
about new loT applications and breakthroughs, you'll likely find helpful
information online in the "Internet of Things (IoT) Resources" feature at
circuitcellar.com/featured/iot-resources.

And it's a list that's expected to grow. If you know of a resource that should
be added, please email it to CJ Abate and Mary Wilson on editor@circuitcellarxom.ome up with proper
answers, simple and easy to understand to help you to take the next step on your favorite embed-
ded platform. That step is called Arduino.next and will be up & running soon— powered by Elektor,
Stay tuned to our communication channels!

Follow us on Facebook, www.facebook.conn/arduinonext, and on Twitter, @ arduinonext,
and check out the Arduino products already on sale at www.elektorxom.

That Sounds Good!

ADVANCING THE EVOLUTION
OF AUDIO TECHNOLOGY

audioxpress.com

In the audio electronics domain, Elektor International Media publishes audh
oX press, Voice Coii t Loudspeaker Industry Sourcebook t World Tube Direc-
tory , books, and more. Those titles were founded in the US by Edward T.

Dell (1923-2013) and for over 35 years served the do-it-yourself audio con-
structor as well as those working in the audio industry with great articles,
projects, tips and technologies.

Believing that the work of enthusiasts should serve as a model for the indus-
try as far as excellence of design and quality of constructions goes, Ed Dell
launched The Audio Amateur in 1970, a magazine devoted exclusively to
DIY audio. Ten years later, believing there was sufficient interest in the loud-
speaker market, Ed launched a separate magazine in 1980, called Speaker
Builder, while a third publication, Glass Audio, responded to the increasing interest in vacuum tube based audio equipment.
In 1996, Audio Amateur was renamed Audio Electronics and in 2000, the three magazines were combined into a single, monthly
periodical, named audioXpress . In 2011, Ed DeJl sold his company to Elektor International Media.

A new editorial team, reinforced by leading authors from the Elektor network, is currently working on a redesign of the pub-
lication with an expanded format, addressed towards the global audio engineering community, covering also the R8tD efforts
in the industry in many new application areas.

The refreshed, restyled audioXpress will be launched at the AES Convention in NY (October 17th - 20th) with a new graphic
layout in print and in full digital front, including a regular newsletter to over 30,000 members (at the time of writing).
audioXpress is already engaging with the giobaf audio community though Twitter (@audioXP_editor) and
Facebook (facebookxom/audioxpresscommunlty). See more at www.audioxpress.com.

www.elektor-magaiine.com November 2013 9

Projects

CAN Tester

With comprehensive features

By Hugo

(Belgium)

circuit described here has all the features
uired for conducting various experiments
tests on a CAN bus. In addition there
the option of connecting the tester to an
existing CAN bus to monitor the data or to
track down faults.

ir to say

that modern vehicles (cars,
trucks, motor bikes, agricultural vehicles,
etc.) have these days become rolling (mobile)
networks. The various control systems in these
vehicles are connected together with a network
used for exchanging messages. In this way it is
ensured that the various functions in these vehi-
cles are functioning optimally.

Many car manufacturers use the CAN bus (Con-
troller Area Network) for this. The control units
are connected together with two twisted wires
(terminated with resistors at the ends) and so

form the CAN network. These wires are called
CAN High and CAN Low. There may be more
than one CAN network in a single vehicle.
CAN is a system that works reliably in an envi-
ronment with high interference. But because
of the complexity of CAN networks it can
sometimes be difficult to solve problems.

I

This is one of the reasons why the Etek-
tor CAN Tester has been developed; the
other reason is that the CAN Tester is also
excellent to gain experience with the CAN
bus and offers the possibility of experi-
menting with software for CAN circuits.

The CAN Tester described here comprises
two identical circuit boards (board A and board
B), which are only loaded with different soft-
ware. Each board can be equipped with a 4x20
size character LCD, The boards communicate
with each other according to the CAN protocol.
These boards can also be connected to an exist-
ing CAN bus.

The CAN Tester offers the following options (using
the same boards):

* Test configuration with boards A and B, for
29-bit and/or 1 1 -bit IDs (automatic);

* Reading out of CAN data on the LCD (for
example parking brake, odometer reading,
etc.);

10 November 2013 www.elektor-magazi ne.com

CAN Tester

• Examine data using HyperTerminal;

• Test functionality with pushbuttons and
LEDs;

• Simulation of messages,

These features will all be discussed in this article,

The SJA1000 is a bitstream processor with a
transmit and receive buffer. This is controlled and
initialized by the ATmegaSSIS, The ATmega851S
provides the transmit buffer of the SJA1000 with
messages and reads out the receive buffer. The
SJA1G0Q is connected to the ATmegaSSIS via a
multiplexed address/data bus (PAD - PA7).

The hardware

We start with a brief description of the hardware
that has been used, In Figure 1 this is shown
for one circuit board, the other board has an
identical design.

The circuit consists of the following components:

• ATmegaSSIS: 8-bit microcontroller (IC1);

• SJA100Q: CAIN protocol controller (IC4);

• PCA82C250: CAN transceiver (IC3);

• MAX232: RS232 transceiver (IC2, for com-
munication with the PC);

• 4 x 20 character LCD (LCD1),

In addition, there are four control signals that go
to the SJA10G0: CS (chip select), ALE (address
latch enable), RD (read) and WR (write). CS (chip
select) has to be logic Low when the ATmegaSSIS
communicates with the SJA1000. The ALE sig-
nal has to be logic High when an address is on
the bus, and logic Low for data. The RD and WR
signals are used to determine whether it Is a
Read or Write command from or to the memory
in the SJA100G,

The interrupt output (INT) of the SJA10Q Is not
used here. With the mode connection input pin of

Figure 1.

Schematic for the CAN
Tester. The main ingredients
are a microcontroller, a CAN
protocol controller and a
CAN transceiver.

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www.elektor-magazine.com November 2013

11

Projects

the SJA100G, the bus interface can be configured
for a microcontroller made by Intel or one made
by Motorola. With this CAN tester that is Intel—
that is why pin 11 of IC4 is connected to V cc .
The ATmega8515 sees the SJA10GQ as an expan-
sion of its (internal) RAM. This is the reason why
in the compiler settings for Bascom the 'EXTER-
NAL ACCESS ENABLE' has to be ticked (see the
box 'Program settings').

The PCA82C250T transceiver ensures that the
data it receives on its TXD pin (TTL level) is con-
verted to the differential signal {as a difference
voltage) of the CAN bus (CanH and CanL, with
the Can-High and Can-Low wires as a twisted
pair, terminated with two resistors of 120 Q).
The received differential data is converted by
the transceiver to a signal with TTL levels, which
goes from its RXD connection to the SJA10OQ.
The ATmega8515 runs at a clock frequency of
8 MHz, the SJA10QQ at 16 MHz. The baud rate
with the serial connection to the PC operates at
a speed of 57,600 baud.

The board is fitted with four jumpers (K3 through
K6), which are used to select whether the LEDs
or the pushbuttons are connected to port D of
the ATmega8515.

The display is used in 4-bit mode and is connected
to port B of the microcontrol ten PI is used to
adjust the contrast for the display.

The MAX232 is an old acquaintance; it provides
for the conversion of the 5-V signals on the board
to the 12-V signals of the RS232 bus.

K9 is used to enable the termination resistor for
the CAN bus.

In addition there is a 6-way ISP connector to
allow the microcontroller to be programmed while
in the board. You can, for example, connect the
STK500 programmer to this.

The entire circuit is powered from 5 V. You can use
a wall adapter with a regulated output for this or
a 9-V battery with a separate voltage regulator
The current consumption is small, for short-du-
ration experiments a battery will be sufficient.

The software

The software is written in BASCOM (demo ver-
sion). The ATmega8515 was programmed with
the STK500 (Atmel), This software is based on
the examples from BASCOM (third party Lawicel),
This software contains the minimum of what is
required to send and receive data frames (mes-
sages). The software configures the SJA1GO0 in
the PELICAN mode. In this mode you can send

and receive 11-bit and 29-bit identifiers.

The software comprises seven parts:

1. First an address is issued to the registers of
the SJA1000 (since the ATmegaBSIS sees the
SJA1000 as an external RAM expansion).

2. An identifier (29 bits) is turned into a 'Long' (4
bytes), with an 11-bit identifier this becomes
a 'Word' (2 bytes).

3. The 'Do Loop' contains the actions that the
program will carry out. From here the subrou-
tines TrartscantesEl, Transcntest2 and Receive-
cantestl are called,

4. The subroutine 'Initsja' is used to initialize the
SJA1000, this contains, among other things,
the setting for the bit rate.

5. The subroutines Transcantestl and Transcant-
est2 ensure that the data frames (messages)
are transmitted,

6. The subroutine Receivecantestl is respon-
sible for the reception of the data frames.
This subroutine also contains what has to be
done with the received data (processing by
the ATmega8515),

7. Display of the data on the LCD (4-bit mode).

The bit-rate of the SJA10G0 is here set to
250 Kbits/s (the same as the J1939 standard).
Other bit- rates can be set in the software, taking
into account the dock frequency of the SJA1000
(16 MHz), You can find various 'bit rate calcu-
lators' on the Internet for the SJA1Q0G, which
wifi give you the values for the registers (tmg_G
and tmg_l).

Further explanation of how the software is put
together can be found in the data sheets and the
application notes for the SJA100Q (with respect
to the registers in this IC),

The software contains comments that provide
further explanation for certain program lines.

In a separate Word document that you can down-
load from [1], you will find an overview of the
features of the available software together with
some explanation.

Construction

In Figure 2 we can see the circuit board that has
been designed for the CAN Tester. This is fitted
with parts on both sides. Most of the components
are fitted on the side with the component overlay.
On the solder side are the LEDs D1 through D6,
the pushbuttons SI through S4 and the 16- way
header for the LCD. The circuit was originally
designed for ICs with 'norma!' pins, but in the

12 Movember 2013 www.elektor-magazi ne.com

CAN Tester

meantime two of the ICs used here are now only
available in SMD version: the PCA82C250 (IC3)
and the SJA1000 (IC4). In order to be able to
use these on the existing circuit board we have
used small adapter boards (available from [2],
among others). For those who buy the prepro-
grammed controller we will also supply the two
adapter boards with it, so that you can get started
immediately*

The LCD is not necessary for all of the test con-
figurations. It all depends on the firmware used
(see also the additional documentation available
as a free download [1],

There is a sub-D9 connector for the connection
to the PC, You can , if necessary, connect a USB/
RS232 adapter cable to this for communicating
with a modern computer.

All the firmware is of course available as a free

COMPONENT LIST

Resistors

R1,R2,R5-RS = lkQ
R4,RU = IGkQ
R3,R9,R1G = 120Q
R12 = 330ft

PI = 10kQ trimpot, e.g. Bourns 3386P-1-1Q3LF, New-
ark / Parnell # 9355030

Capacitors

C1-C4 = 22pF
C5-C9 = IpF 63V radial

Semiconductors

D1-D6 = LED, red, 3mm

IC1 = ATmega8515-i6PC, programmed, Elektor Store

# 120195-42a for board A, # 120195-42b for board

B

IC2 = MAX232ACPE

IC3 = PCA82C250 (8-pin DIP) or PCA82C250T (S08,
adapter board required)

IC4 = SJA100Q (28-pin DIP) or S1A10OGT (S02B,
adapter board required)

Miscellaneous

XI = SMHz quartz crystal
X2 = 16MHz quartz crystal
LCDi = LCD, 4x20 characters (Elektor Store #
120061-73)

K1 = 16-pin pinheader, 0.1" pitch
K2 = 6-pin (2x3) pinheader, 0.1" pitch
K3-K6 = 3-pin pinheader, 0.1" pitch, with jumper
K7 = 9-way sub-D socket, right angled pins, PCB
mount

KS,K1G = 2-way PCB screw terminal block, 0.2" pitch
K9 = 2-pin pinheader, 0,1" pitch, with jumper
S1-S5 = miniature pushbutton with make contact,
e.g. TE Connectivity 3-1437565-0, Newark / Farnell

# 2060813

PCB # 120195-1, see [1]

Figure 2.

The circuit board contains components on both sides:
on one side the LEDs, pushbuttons and the display, on
the other side all the other parts.

www.elektor-magazine.com November 2013

13

Projects

Program settings

In BASCOM the compiler has to be configured by selecting under:
OPTIONS/Compiler/C 'External Access Enable'.

The settings for AVR Studio 4 together with the STK500 are as
follows:

*

m
[

AVR Studio

Disconnected Mode Open Connection Dialog to Rec**.

x

1(0

M

4

Ptogfam i Fuses LockBits | Advanced | Board j Auto

Device

AT mega 851 5

~z\

Erase Device

Pfogramming mode
a isp

C" Pardlel/High Voltage Seiial

R E rase D evice B elore Progra mmirvg
^ Verify Device After Programming

Flash

r Lise

S milator/ErrsMof FLASH Memory

& Input HEX File |E:\Progtann FiesVMCS E lectronicsNB AS COM-

Program

Verify

Read |

EE PROM

C ij *e C u: i en t Sirr lulatof/Erndlalot EEFRQM Memory

Input HEX Fite |E:\Dccumert& and Setting$\Hugo\Miri doeu

Program

Vetify

Read

The fuses are set in AVR Studio as follows:

Boot Flash section size = 128 Boot start address =$0F80; BOOTZ = 11
Brown-out detection level at VCC = 2.7V; (BODLEVEL = 1)

Ext. Crystal/Resonator High Freq.; Start-up time: 16K
CK+64ms;(CKSL = 1111 SUT = 11)

download from the Elektor website [1],

Each application requires a different firmware.
In the interest of simplicity, Elektor Store only
supplies the preprogrammed microcontrollers for
application 4, which is described a little further
on (120195-42a and b).

Applications for the CAN Tester

Here follows a brief description of the various
applications, where each time also the necessary
firmware versions are mentioned.

Application 1: Board A and board B send
and receive messages automatically to
each other

firmware; 120195-40a (hoard A without LCD)

120195-40b (board B without LCD)

120195-413 (board A with LCD)

120195-41b (board B with LCD)

Here, both boards send and receive messages
to each other with 29-bit IDs, Each message
contains 8 data bytes, of which only one data
byte used.

Board A transmits messages that are only
intended for board B, and board B sends mes-
sages that are only destined for board A. Mes-
sages are received the same way: Board A only
received messages from board B and the other
way around.

The transmitted data byte appears on port D of
the microcontroller and is made visible on both
boards using the four LEDs, which turn on and off
two at a time. This also signals that there is con-
tinuous data traffic between the two boards. That
therefore also means that the wiring between the
boards is correct.

You can use this function only to test the wiring
of a CAN network. You can connect the boards
to any arbitrary point on the network wiring. You
connect the boards (A and B) to the ends of that
section of wiring that you would like to test. Take
into account any termination resistors that are
on the CAN network already (and if necessary
disconnect them), each board of the CAN -tester
has a termination resistor of 120 Q t which you
can switch in or out with jumper K9 (the bus
impedance is 60 Q).

With this setup you can test:

* interruption of CanH;

* interruption of CanL;

14 November 2013 www.elektor-magazi ne.com

CAN Tester

Consider your safety!

Know what you are doing! When the CAN Tester is connected to a vehicle and you send
messages (data frames) on the network, then it is possible for engines to start automatically,
vehicles starting to move by themselves, engines to reach high RPM, etc. Take the time to work
safely, don't endanger yourself and others* Closely follow the instructions from the manufacturer
and the vehicle. And read the SAFETY instructions.

• CanH and CanL swapped;

• CanH and CanL shorted;

• Moisture in the cables (plugs submerged in
water).

When any of these faults appear or are present,
then the LEDs will stop flashing immediately.
When the fault disappears the LEDs will start to
flash again. In this way you will have a visual
indication of a fault. To track down intermittent
faults you can shake the wires and plugs about
while at the same time keeping an eye on the
CAN Tester.

The CAN Tester works optimally on an inactive
network, in this case the CAN bus is entirely avail-
able to the CAN Tester, It also works on an active
network, but the LEDs will flash slower in this
case because there will also be other data traffic
on the bus. When the LEDs flash that means the
messages from the boards are sent and received
in between the other messages.

Application 2: Single CAN Tester with LCD
( handbrake , odometer reading, etc,)

Firmware: 120195 -44a (board with LCD , handbrake)

120 195 -44b (board with LCD ; odometer reading)

120195-45a (board with LCD , accefeartor)

In this application the CAN Tester only receives
messages. These are displayed intelligibly on the
4x20 character LCD.

The three examples are:

a) status of the handbrake of a truck;

b) the odometer (miles counter) reading;

c) accelerometer position.

These examples show how you can process the
received data into a legible result with the aid of
a few operations. This can also be used for diag-
nostics, for example if you would like to read a
certain sensor during a test drive-
in this application the CAN Tester is connected

www.elektor-magazine.com November 2013

15

Projects

to the network of a vehicle that transmits these
messages.

If you do not have a vehicle available to you,
then you can also simulate these messages with
another board. To simulate messages you can f
for example, use the Tiny-CAN View (see Auto-
motive CANtroller, Elektor February 2009 or the
CAN Explorer, Elektor February 2008).

Application 3: Viewing data using Hyper-
Terminal (baudrate = 57,600)

This is possible with all version of the firmware
The CAN Tester has a MAX232 for communicating
with a PC. The software is written in such a way
that we can examine the contents of messages
on a PC via the serial port. This applies to both
the sender and the receiver.

The received data can also be stored in a file
(via the HyperTerminal program). This can be
all messages, or only those that are of interest
to you. You can set that yourself in the software.
For example, each program contains the part
number of the software that is in the microcon-
troller at the time. This is very handy when you
are using multiple controllers (running different
firmware). By connecting them to a PC you can
see which program it contains,

Application 4: CAN Tester with pushbut-
tons and LEDs

Firmware: 120195-42a (board A, with LCD)

120195-42b (board B with or without LCD)

This application requires two boards (Board A
and Board B).

The messages have 29-bit identifiers and the bit-
rate is 250 Kbits/s (J1939 protocol).

We use two pushbuttons and two LEDs, Place the
jumpers in the correct positions for this:

• Ports D4 and D5 to the pushbuttons (jump-
ers K5: 1-2 and K6: 1-2).

• Ports D2 and D3 to the LEDs (jumpers K3:
2-3 and K4: 2-3).

Both boards (A and B) can receive and transmit
messages.

Board A:

A message is sent on both the press and the
release on one or both pushbuttons. This trans-
mitted message causes the LEDs on board B
to turn on or off (LEDs turn on when pressing
the pushbuttons and turn off when released).
Only one data byte is sent, with identifier

0C1F134A(H),

Board A receives only messages from board B,
which consist of one data byte with identifier
0C1F1315(H),

Board B:

A message is sent on both the press and the
release on one or both pushbuttons. This causes
one or both LEDs on board A to turn on or off
(LEDs turn on when pressing the pushbuttons
and turn off when released). Only one data byte
is sent, with identifier 0C1F1315(H).

Board B receives only messages from board A,
which consist of one data byte with identifier
QC1F134A(H). The received data byte contains
the information of what the LEDs should do.

When receiving the messages the identifier has
to correspond with the one that is mentioned in
the software, otherwise the data is not copied to
port D, Board A accepts only the data from board
B and the other way around. The LCD shows the
state of the pushbuttons and LEDs.

You can use the CAN Tester in this application in
various ways, for example when testing the wiring
of a CAN network. When operating the pushbut-
tons on board A the LEDs on board B have to fol-
low these pushbuttons, and the other way around.

This configuration and software has also been
tested in an active network (which also car-
ries other messages). This works, but is slower
(always check which identifiers you use, these
may not be the same as those already in the
active network).

In this application too, the CAN Tester works best
when the wiring of the network does not contain
any other activity.

Application 5: The CAN Tester as a simu-
lator for messages

Firmware; 120195-43a (board A with LCD , see additional
documenta tion 1 201 95- W).

120195 - 43b 1 (board B with LCD, see additional docu-
mentation 120 195 -W),

With this firmware it is possible to simulate mes-
sages; you program messages In one board and
use the other board to show them on the LCD
or display them via HyperTerminal. These mes-
sages can be transmitted automatically with a
certain repetition frequency (repetition time) on
the CAN bus. You can also transmit them when

16 Movember 2013 www.elektor-magazi ne.com

CAN Tester

F

a

1

'V

M

Figure 3,

The test setup for
application #4. The supply
voltage is provided by a 9-V
battery and a 7805 voltage
regulator*

operating the pushbuttons*

Firmware 120195-43a: sending messages; firm-
ware 120195-43bl : receiving messages*
Examples and explanation of messages are at [3].
To test the boards (for displaying data on the
LCD), you can again use Tiny CAN View or use
the CAN Explorer.

Finally

The CAN Tester always has to be connected to
another board, vehicle or other test setup such
as Tiny CAN View or the CAN Explorer from Elek-
tor. We wish you much success with your tests
and experiments. (120195-1)

Internet Links

[1] www.elektor.com/120195

[2] www, futudec.com/SHD_Adapters.shtml

[3] www.fms-stand3rd.com/down_load/fms_doc-
ument_ver02*00vers_l 1_1 1_20 1 0. pdf

www.elektor-magazine.com November 2013

17

Projects

Elektor Linux Board:
New and Improved!

Now with LAN and real-time clock

Benedikt Sauter [1]

The compact and low-cost Elektor Embedded Linux
board has been available to buy for around a year
and a half now. Along with its accompanying
series of articles it offers even beginners
access to the world of embedded
Linux, It is now time for us to update
the board based on feedback from
the user community-

Many

users have
pressed the
Elektor Linux board
(and its cousin, the
Gnublin board) into service
for logging data such as tem-
perature and energy use, and then
making the results available over a net-
work* Hence it is dear that a built-in network
Interface and real-time clock would be useful
additions for an update to the board (Figure 1),
We have also incorporated other suggestions
made by users; for example, the fixing holes
are bigger, so that the board can be mounted
more easily.

Eagle format; a free Eagle viewer is available
at [7], and a good book on Eagle at [12].
Network access Is provided using a special-pur-
pose device, as the LPC3131 processor does not
have its own integrated Ethernet hardware. The
Microchip ENC28J60 [8] will be known to some
readers as a network adapter popular for use with
simple 8-bit processors. It is connected using an
SPI port and an interrupt signal. A suitable driver
for this device has been available in the kernel
archive for some time*

The real-time dock (RTC) device chosen is the
MCP7940 [9], which requires an external crystal.
If a coin cell is added to provide back-up power
the RTC will continue to keep time even when
the board is switched off.

An extra serving of chips

The basic circuit of the board has not changed
since the first version [2]. Alongside the proces-
sor we see 32 MB of RAM, a CP2102-based USB-
to-serial adapter, and the power supply circuitry.
Also familiar from the first Elektor Linux board will
be the 14-way expansion connector, which allows
a wide range [3][4] of extension boards (again
available from Elektor [5]) to be connected. The
circuit diagram and printed circuit board layout
can be downloaded from the Elektor website in

Configuring the network

The first step in using the EMC28J6G LAN device
on the board is the command

modprobe enc2S]60 irq_pin=12 cs_pin=19

should show the device as interface 'ethQ'.

In order to have the board receive an IP address
from a DHCP server elsewhere on the network,
use the command:

18 November 2013 www.elektor-magazi ne.com

ELEKTOR Linux board nnk. 2

USB OTG
(devke/host)

RJ45

network socket

USB

power selection

USB OTG

Relay output
terminal block

Relay

Boot configuration

ENC28J60

Reset

Console

Power source
select:

USB/external

Ex pans Eon
connector

RTC and coin cell

5D Card

Power input, 7 V
to 12 V: ground
on central pin

GND

3,3 V DC output

Main memory
(32 MB SDRAM)

LPC3131
(ARM929, 180 MHz)

1015

1014

1011

GPA1

Figure L The new version
of the board includes a
network interface and a
real-time clock.

ifconfig -a

should show the device as interface 'ethQ',

In order to have the board receive an IP address
from a DHCP server elsewhere on the network,
use the command:

dhcli ent etbe

We can now test the interface by pinging any
other machine on the network or server on the
Internet:

ping google.de

The output should appear as shown in Figure 2.
Stop the 'ping' program in the usual way by
pressing control-C.

Loading the driver automatically

If you would [ike the ENC2816Q driver to be loaded
automatically when the system boots up, add
the line

enc28j60 irq_pin=12 cs_pin=19

to the hie '/etc/modules' in the board's hie sys-
tem, This is most easily done from the console.
The command

echo “enc28j6© irq„pin=12 cs_pin=19” >> /

etc/modutes

will append the given line to the end of the file.
Alternatively, the fife can be edited using the
'nano' text editor:

nano /etc/modules

Using a fixed MAC address

If the board is being issued with a different IP
address by the DHCP server each time it is booted
the reason is likely to be that the EIMC28J6Q does
not contain a fixed MAC address: each time the
driver is loaded it is configured with a different
address. A fixed MAC address can be specified to
get around this problem. Add the following line
in the file '/etc/network/interfaces 1 :

hwaddress ether MAC-ADDRESS

A suitable choice might be the one given to the
LAN module the first time its driver is loaded. This
can be determined using the command

i fconfi g

where it Is displayed as the J Hwaddr' as follows:
ethe Link encap : Ethernet HWaddr

www.elektor-magazine.com November 2013

19

Projects

Figure 2. Results displayed
by a successful 'ping'
command: we are on the
Internet!

ba : 07 : lb : Gc : 64 : GO

Real-time clock

A simple command is all that is needed to set
the clock:

gnublin-rtc ~s “2G13/G1/2G 11:23:12”

To read back the time from the device, use the
command:

gnublin-rtc -g

To set the Linux system clock from the RTC, use
the command:

gnublin-rtc -x

Having the Linux dock automatically set from the
RTC on each boot-up takes a little more effort
First add the following text In the file Vetc/rc.lo-
cal', just before the line that reads 'exit O':

echo mcp7940 GxSf > /sys/bus/i 2c/devi ces/
i 2c-l/new_device

echo “Now setting the date and time.”
sleep 1

hwclock — hctosys

Second, add an entry to the file '/etc/modules':
rtc-mcp7940

And finally, deactivate the hwclock shell script,
as this can cause problems with this type of real-
time clock device:

updste-rc.d hwclock remove && update-rc.d
hwclock. s h remove

On the next reboot the board will set the system
time from the hardware clock, More informa-
tion on this subject can be found on the Gnublin
wiki [10],

The future

A new version of the Gnublin installer is avail-
able [11], which allows a Linux PC to be used to
create an SD card including bootloader, kernel
and file system. The new version offers the choice
between an 8 MB image and a 32 MB image.
This is accompanied by a change to the underlying
file system: EXT4 is now used, which is practi-
cally fail-safe in the event of loss of power. This
avoids the need for time-consuming file system
checks required to 'repair' the SD card.

We will look further at this and more in an article
in the next issue,

(130214)

Internet Links

[ 1] sauter@embedded-projects.net

[2] www.elektor.com/120181

[3] www.elektor.com/120596

[4] www.elektorcom/130212

[5] www.elektorxom/gnublin

[6] www.elektor.com/130214

[7] www,cadsoftusaxom/down!oad-eagle/
freeware

[8] http://wwl.microchip.com/downloads/en/De-
viceDocZ39662A.pdf

[9] http://wwl.microchip.com/downloads/en/De-
viceDoc/22266D.pdf

[10] http://en.gnublin.org/index.php/
RTCJ3S13Q7

[11] http://en, gnublin, org/index.php/
Gnublin_Installer

[12] www.elektorcom/eaglestarterguide

PING google.de (173.194,69,94) 56(84) bytes of data,

64 bytes from bk-in-f94, ielO0.net (173.194,69.94); icmp_req=l ttl=49 time=44.3 ns

64 bytes from bk-in-f94.lel0O.net (173.194,69,94): lonp_req=2 ttl=49 ttme=44,7 ms

64 bytes from bk - in - f94 , lelQO . net (173.194,69.94): Lcmp_req-3 ttl-49 tlme=43 . 3 ms

64 bytes from bk-in-f94.lel00.net (173.194,69.94): icmp req*4 ttl-49 tlme=43.4 ms

— google.de ping statistics —

4 packets transmitted, 4 received, 0 % packet loss, time 3004ms
rtt min/avg/max/mdev = 43,308/43,968/44.784/0.673 ms

20 November 2013 www.elektor-magazi ne.com

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Projects

By

Jean-Jacques Aubry

(France)

Important update to the Elektor

500 ppm LCR Meter

Since this project was published in three installments [1], several hundred of the
instrument have been built, to the great satisfaction of their users, the author,
and Elektor editors alike. The author has now corrected two shortcomings liable to
interfere with proper operation under certain conditions.

The two points worthy of attention are the fact
that the instrument seems to 'hang up' when
measuring low resistances (<1 CJ); and the appar-
ent impossibility to perform Trim actions. The
author has already commented and acted on
these problems in the Elektor forums [2], [3],
but it's useful to revert to them here.

When measuring resistances with a value lower
than 1 Q , in order to obtain an adequate mea-
suring voltage, the firmware sets the "voltage''
measurement gain to maximum:

• range 1 (/? sense = 100 Q. and PGA103 gain at

100 );

■ final amplification gain dose to maximum
(step E or F).

Unfortunately, the input offset voltage is strongly
amplified as well, and using the circuit published
in the March 2013 edition, this is no longer com-
pensated. This can lead to the maximum voltage
at the input to the analog/digital converter being
exceeded all the time. This erratic phenomenon
is not systematic and depends to a great extent
on the cumulative offset voltage of U6 and U4,
and on the (low) resistance (or inductance) being
measured. So that's the first one!

As for the second, when there is no component
connected during the 'TRIM - OPEN-CIRCUIT'
operation, here too the 'current' measurement
gain is maximum at the frequency of 100 Hz
(or 120Hz):

• range 8 - 100 kQ and PGA103 gain

at 100);

• final amplification gain dose to maximum
(step E or F).

At this point, the 'current' measuring circuit is
very sensitive to interference picked up by the
measuring leads, particularly from the power line
(50 Hz or 60 Hz). The result of the measurement
is so erratic that the firmware refuses to display
it, and does not validate the 'TRIM", So much
for the second one I

Two problems^two solutions

Depending on whether you are handy with a
soldering iron or not, there are two solutions:

* Modify the hardware—the best solution— to
enable the input offset voltage compensa-
tion circuit to be adapted, and at the same
time update the firmware (v. 3,0.0) along
with the AU2Q11 program (v, 3,0.0). The
software will automatically detect the hard-
ware modification at runtime, due to the
presence of a resistor on the P2.2 port line
(LCD_SI) (Figure 1).

* Update with the same versions of the
firmware (v, 3.0.0) and AU2011 program
(v. 3.0.0), without modifying the hardware.

Important: Updating the software to version
3.0-0 must be done in either case. The new
version is equally compatible with the origi-
nal hardware and with the modified version
described below.

Modifying the hardware

As originally designed, input offset voltage com-
pensation is achieved by injecting a current into
U6 r s input. Unfortunately, the result is too depen-
dent on the (DC) resistance of the DUT.

The new circuit (Figure 1) applies the correction
voltage at the output of U5 (INA12S), and hence

22 November 2013 www.elektor-magazi ne.com

500 ppm LCR Meter V. 3.0.0

the DUT impedance no longer has any effect; this
also makes it possible to separate the compensa-
tion for the 'current' and Voltage' measurements.
To achieve this, US's pin 5 is no longer connected
to analog ground, but to a software-adjustable
voltage via a low-value resistor.

There are four steps to the modification;

* remove R34 to disable the original compen-
sation. R42 and C35 are no longer used and
can also be removed;

* replace R46 by a 10 Q resistor (prefers-

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Partial schematic with
corrections to be made to
improve the 500 ppm LCR
Meter.

www.elektor-magazine.com November 2013 23

Projects

Figure 2.

Modifications to the offset
voltage compensation circuit
around U5,

Figure 3,

Don't try to unsolder pin 5
on UB^you risk disaster!
Use a scalpel to isolate
it, then re-make the
connections using wire*

Figure 4,

This resistor tells the
firmware that the circuit has
been modified as shown in
Figures 1, 2 and 3.

bly 0305), The 10-Q resistor can also be
soldered directly across the 680-12 resistor
that's already there;

• the third step is more tricky: US's pin 5
must be isolated from its present connec-
tions and connected to the junction of R45,

R46, and R47. It's possible to do this by
lifting pin 5, but we advise against this,
as you should not take the risk of dam-
aging U5. So we suggest instead making
a clean cut in the (visible) tracks between
U5.5 and C27, U5.5 and C34, and U5.5 and
the through-hole adjacent to J14 (Figure 2),
You'll then need to reconnect C27 and C34
to the through-hole (analog ground) via
small wires (Figure 3); and use a short wire
to create the new fink between U5 pin 5 and
the junction of R45, R46, and R47;

* solder a 4,7 kQ to 10 kQ resistor between
pins 9 and 11 of 117, on the opposite side
of the PCB (Figure 4)* The presence of this
resistor will allow the firmware to detect the
modified circuit.

New programs [4]

The version 3,0,0 firmware (LCR3A_firmware_
V300.hex) supports the new input offset voltage
compensation circuit if, and only if, a resistance
to ground is detected on pin 9 of J17

This results in a re-arrangement in the menus
in the AU2011 program, which also updates to
version 3,0.0:

the original Input_offset adjustments menu
is replaced by two menus Inputs offset^ U
adjustment .. and Input_offset_I adjustment .. ,
the first with the input shorted, the second
with it open circuit.

For users who do not wish (or are unable) to
modify the hardware, the solution consists in
limiting the overall gain In range 1. Hand-in-hand
with this, similar limiting can be performed in
range 8, if there is too much interference in the
surroundings, preventing the TRIM ~ OPEN-CIR-
CUIT compensation being performed correctly.

The gain limiting solution Is valid whether
or not the device has been modified.

The initial maximum value will be 5 for an unmod-
ified device and 15 (step F) for a modified device.
Naturally, the value modifications are stored in
the device's memory, just like the other settings/
options in the Preferences window.

It follows that we also have to add two menus
in standalone mode, and modify the Preferences
window in PC mode when the access to adjust
menus option Is checked (Figures 5 & 6),

Other modifications have been made to improve

24 November 2013 www.elektor-magazi ne.com

500 ppm LCR Meter V. 3.0.0

convenience in use, like the appearance of a "Port
/ Close the Port" menu, handy if you originally
chose the wrong port; all you then have to do
is select the right port and click the 'Open COM'
button in the main window.

Measuring high impedances

The 'voltage' and 'current' signals are amplified
with no low-frequency filtering prior to sampling.
It is only after digitizing, by performing the mea-
surement over a whole number of AC power-
line cycles and taking the average of several
measurements, that it is possible to reduce the
influence of the stray signals picked up by the
measuring device.

This means it is possible for the signal applied
to the analog/digitai converter (ADC) to briefly
exceed this ADC's input range and invalidate the
measurement.

Consequently, particular care must be taken when
measuring high impedances, when the LCR meter
is set to range 7 and above all 8; this is the case
during TRIM - OPEN-CIRCUIT.

• Put the electronics in an earthed metal case
(iron is preferable to aluminum at low fre-
quencies). Take care if you are using the
LCR Meter in standalone mode with a USB
supply, or in PC mode with a laptop: in these
cases, there is no earth connection and you'll
need to make one. The power plug on a USB
PSU doesn't have a pin to connect the LCR
Meter case to the AC powerline protective
earth; and a laptop running on its battery
isn't earthed either.

• Minimize the length of the measuring cables,
and keep away from power cords. To protect
the device and the measuring leads from
radiated fields, place a grounded metal plate
(preferably iron) of adequate size between
them and any powerline wiring.

• If there is still interference, reduce the gain
of the measuring chain to range 8 (Max
DACIndex I in standalone mode).

To conclude, let's just note that experience has
shown that in practice, the 4-BNC measuring unit
solution (TONGHUI TH260G1A or HAMEG HZ181)
is very much preferable to the Kelvin clip.

(130307)

Back Light OFF
Line freq. 60 Hz
Hdj .Max DRC Index U
Rdj .Max DRC Index I

Figure 5.

Two new menus in
standalone mode.

Internet Links

[1] 500 ppm LCR Meter

Part 1, Elektor no. 417, March 2013
www.elektor.com/ll 0758
Part 2, Elektor no. 418, April 2013
www. elektor. com/1 30022
Part 3, Elektor no. 419, May 2013
www.elektor.com/130093

[2] www.eiektor.fr/forumLCR (in French)

[3] www.elektor.com/forum/elektor-fo-
ru m s/fie Id s-of-i nterest/test- measu re -
ment. 1 543743. lynkx

[4] www.elektor.com/ 130093

Figure 6.

The 'access to adjust,
menus' option under the
Preferences in PC mode.

www.elektor-magazine.com November 2013 25

Projects

Multichannel
Temperature Logger

By Ihab F. Riad (Physics
Dept., University of Kar-
toum, Sudan) (a hot place)

This project allows you to log up to six
temperature readings over a period of
time, complete with time stamps, all
written to a .csv file stored on an SD
card for processing on a PC. Local con-
trol is also available in the form of an
LCD and a keypad.

Features

* Max. six D518S20 1-Wire temperature
sensors

• PIC18F4520 based

* 1 second minimum logging interval

• Writes time-stamped .csv data on SD/
MMG card

• Local control with LCD and keypad

* On-board RTC

The main components found in this project are
the DS18520 digital temperature sensor, the
RTC-DS1338 Real Time Clock, and a microcon-
troller type PIC18F4520. Due to the ±0.5 °C tem-
perature resolution of the sensors and a minimum
logging time of 1 second, this logger is most
suitable for environmental monitoring, like your
focal temperature at six fixed height intervals
above the ground.

The sensors

First off, you can use a maximum of six DS18S20
temperature sensors to capture an equal num-
ber of temperatures at remote locations. If your
application requires just two or three sensors,
that's fine too.

Looking at the schematic in Figure i, the remote
sensors are connected to 3-pin connectors K3
through K8 using the 1-Wire system (which actu-
ally involves three wires). As opposed to some
previous projects like our Thermo-Snake [1], here
the DS 18520 is used in standard 1-Wire mode

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rather than in 'parasite power' mode. Rather than
being connected to a common line or 'bus', each
DS18S20 sensor has its own PIC port line RAG-
RA5 and associated resistor network (R22/R28
and so on) connected to its DQ (data in/out) line,
The DS18S20 being a 1-Wire component, each
device ever produced by Dallas Semiconductors
has a unique 64-bit identifier stored in ROM. The
device sends messages using the format illus-
trated in Figure 2,

Into the schematic

Returning to Figure 1, RTC chip IC1 supplies the
time stamps for the logged data to the micro,
using PC lines SDA and SCL. The DS1338 has its

26 November 2013 i www.elektor-magazi ne.com

Multichannel Temperature Logger

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Schematic of the
Multichannel Temperature
Logger. Besides yours, some
intelligence resides in the
PIC18F4520,

traditional 32.768-kHz watch crystal, and oper-
ates off a 3.0-volt button cell, BT1, or 33 V when
the board is powered.

A commercial 4x4 matrixed, numeric keypad on
microcontroller port lines RDQ-RD7 and connec-
tor Kbl is used for setting the time/date and
the logging interval. The keypad is also used to
start and stop the logging. A 2-line, 16-character
(2x16) LCD type DOGM162 (what's in a name?)
is used to display the current time and date, as
well as the instantaneous temperature from one
of the sensors. The LCD's backlight (BL) function
is controlled with T1 responding to control lev-
els issued by the PIC micro on port line RE2. An

SD/MMC card on the 'Cardl' connector holds the
logged data. All read/write access and control of
the SD card is via five lines on microcontroller
port RC. The card can be removed and the file
on it read on a PC for processing by your favorite
statistics or graph rendering program capable of
processing .csv files. Lots of nicely colored graphs
in particular work wonders on CFOs, CEOs, CCOs,
CYOs, CXYZOs and other non-electronics initiated
persons in the audience.

The internal fuse settings enable the microcon-
troller to be clocked by an external 8-MHz quartz
crystal, X2. With the interna] PLL enabled, the PIC's
actual CLK is 32 MHz, The crystal is flanked by the

www.elektor-magazine.com November 2013 27

Projects

Figure 2.

1-Wire message format and
pinout of Dallas' DS1852G
1-Wire temperature sensor.

M-BIT C Rl

MSB

SfcRtAL NUMBER

LSB MSB LSB

^ BIT FAMILY COD I : (2Kb)
MSB LSB

DS18S2Q

OQ

customary pair of 22-pF ceramic load capacitors.
A word or two about these apparently paltry little
parts. Get these wrong and funny things may hap-
pen, Like C or C++ experts and other program-
ming gurus fitting "yeah-weEI-something" parts
In the "elector" circuit and subsequently spending
hours on debugging the code, meanwhile creating
long forum threads all across California right up
to MIT Boston and across the ocean to Limbricht,
all because the micro is running at a speed that's
wildly different from what the designer planned,
The upshot: get the xtal load capacitors wrong
and your PIC oscillator will not work.

Back to digitalism, connector K1 is the gateway
to the Microchip PICKit.

Two LEDs are provided: D2 to show logging activ-
ity, and D1 to show card detection.

The 3,3-V supply voltage for the entire circuit
is furnished by a low-drop regulator, IC3, The
maximum input voltage will be about 18 V (but
don't push It), the minimum, about 4,6 V, Four

AA 1.5-volt dry batteries will last a long time.

Applications and how it was developed

The first unit was built by the author to monitor
the temperature variation at different points in a
concrete slab just after the mixture was molded,
and during hardening. That was for an M.Eng,
student. The unit was primitive at that time with
no more than the keypad and the LCD, The fog-
ging was done manually every few hours for a
couple of days.

One member at www.elektoMabsxom suggested
putting four sensors on a stick at 1-foot (30cm)
intervals above the ground and two sensors in
the ground. This will give you a good idea of the
temperatures in your garden.

The original code was written using PIC MIKROC
from Mikroelektronika, Testing and debugging was
carried out with the help of an Easypic6 devel-
opment board from Mikroelektronika, their RTC2
module, and their MMC/SB board. The author's

Petit FAT Fs

PetitFAT File System (Petit FATFs) Is written in compliance with ANSI C, and
completely separated from the disk I/O layer. It can be incorporated into tiny
microcontrollers with a small memory even if the RAM size is less than sector size.
Petit FatFs features include

* very small RAM consumption (44 bytes work area + certain stack);

* very small code size (2-4 Kbytes);

* supports FAT32;

* single volume and single file;

* file write function with some restrictions.

In terms of the Application Interface, Petit FATfs provides the following functions:
pf_mount (mount/unmount a Volume); pf_open (open a file); pf_read (read file);
pf_write (write file); pfjseek (Move read/write pointer); pf_opendir (open a
directory); and pf_readdir (read a directory item),

PetitFat Fs is completely separated from the disk I/O layer, hence it requires certain
lower-layer functions to read the physical disk. The low level disk I/O module is not a part of Petit FatFs module and It
must be provided by user. The sample drivers called diskjnitialize, disk_readp (partial) and dlsk_writep (partial) are also
available in the resources [4].

Application

28 November 2013 i www.elektor-magazi ne.com

Multichannel Temperature Logger

original test setup is pictured in Figure 3. While
processing the project for publication here, new
software was developed by Elektor Labs using
their Microchip MPLAB X environment and C18
compiler.

The SD card is read, and written to using Petit
FatFs, a sub-set of the FatFs module for 8-bit
microcontrollers, see inset.

The 1-Wire protocol got implemented with the
help of a CIS library at [2]*

All PIC source code fifes for the project have been
packaged into a .zip archive fife to be found at
[3] for free downloading.

The log file

The temperature logger expects a file called Tern-
pLog.csv on the SD card. The logger is unable to
create a new file or adjust the size of a file. At the
start of a new log session this file is opened and
overwritten starting from the first record. Con-
sequently, some measurement values remain in
place if the new session contains fewer samples
than the previous one. It is therefore recom-
mended to use your PC to write a new, blank file
to the SD card prior to a new logging operation.
This empty file is included with the free software
download from the Elektor website [3]— but can
also be created from scratch, see [4], Quick 8t
dirty, to create a new log file, type:
fsutil file

createnew\ < [driveletter >: <fi le size in
bytes>

The default size of our file is 5 MB, but tailor the
size to your liking.

In terms of measured values appearing on the
LCD, T(emp,)0 is the sensor wired to KB (near-
est the display), T1 to K7, and so on, up to T7
on K3 at the lower side of the PCB.

A new line/record is written into the TempLog.
csv file for each new measurement, Columns 1
and 2 contain date and time respectively. In the
next columns the measured temperatures appear
in order (see above paragraph) of the connected
sensors- For example, if only one sensor is con-
nected, its output value appears in the third col-
umn, regardless of the connector it is wired to
or plugged into.

So You Think You Can

Have a go at changing that 8-MHz existing micro-
controller oscillator frequency. Feel free to do
so—here's what you're up against in terms of
delays that need to be adjusted:

* in file Globals.c: adapt delay_ms, delay_
us, setup_io (SSPADD).

* in file LCD.c: adapt XLCDdelaylSms, „.4ms,
,.,100us, ...500ns, XLCDdelay.

* in file SW_I2C.c: all functions,

* in file Onewi re . c: ow_reset, ow_wri te_

Figure 3.

This how the project
got developed at the
author's home using a
Mikroelektronika EasyPIC6
development system and
some add-ons.

www.elektor-magazine.comt November 2013 29

Projects

Key Functions

The keypad Is basically a DTMF (telephone) type with numbers 0-9, letters A-D, the hash sign
£#), and an asterisk (*)* The key functions are summarized below. Keys presses do not produce
DTMF sounds,

A: Adjust logging interval

0-9: Change number (advances automatically)

D: Exit the setting menu

Note that after every unit (hour, minutes, seconds), that unit ts updated only— not the rest.

B: Start/Stop logging (LED indicates logging In progress)

C: Set Clock

0-9: Change number (advances automatically)

D: Exit the setting menu

Note that after every unit (hour, minutes, seconds), that unit is updated only— not the rest.
0-5: Selects sensor to be displayed on LCD

Display Codes:

Startup:

C

L

K

■

d

wd

wd

d

■

d

mo

mo

y

y

R

E/U

S/N

h

h

mi

mi

s

s

Home (x -

= sensor number):

T

X

di

*

wd

wd

d

d

mo

mo

y

y

(-)

T

T

d

T

h

h

mi

mi

s

s

Set time:

S

e

I

wd

wd

d

d

mo

mo

y

y

t

m

e

h

H

mi

ml

s

s

Adjust log:

S

e

t

1

0

g

i

n

t

e

r

V

a

i

h

i

h

h

m

i 1

m

m

s

■

i-

s

s

byte, ow„read_byte, ow_read_bi t,
ow_get_ temper atu re .

* in file mmc * c : di sk_i ni ti ali ze,
ini t_spi ,

All done? Then post your results to the commu-
nity at www, el ektor-labs.com.

Construction

The circuit board designed by Elektor Labs for
the project is shown in Figure 4, along with the
parts list* The board's overall shape and dimen-
sions are governed by the LCD and the keyboard
installed on top of it. Etchers@home: the PCS
♦ pdf files are at [3]. Apart from a good number

of 0,1" pitch pinheaders, a button cell holder
and 0*1" pitch socket strips with turned pins,
the board contains mostly SMD parts. Of these,
the PIC microcontroller will be the most both-
ersome to fit, but work calmly and accurately
and it can be done. Methods of hand soldering
these multi-legged parts successfully have been
described many times.

The keypad is mounted on four 15-20 mm stand-
offs to clear the dip on the battery holder.
Finally, the LCD is a fragile device and must be
handled and mounted with the utmost care*

(120637)

30 November 2013 i www.elektor-magazi ne.com

Multichannel Temperature Logger

COMPONENT LIST

Resistors

(SMD 0805)

RljR2 r R21,R28,R29,R30,R31,R32,R33 - lOkQ 5%
125mW

R3,R4,R5,R6,R7,R8,R13 r R14 = 100ft 5% 125mW
R9,R10,R11,R12 = 8>2kft 5% !25mW
R15,R16,R17,R22,R23,R24,R25,R26 = Ikft 5%
125mW

R18,R19 = 1,5ft 5% lOOmW
R20 = 18kn 5% 125mW
R27 = 56kft 5% 125mW

Capacitors

{SMD 0805)

C1,C2,C3,C6,C7 = lOOnF 50V 20%

C4 = l|jF 16V
CS = 470nF 25V
C8,C9 = 22pF 50V 5%

CIO = IGjjF
Cll = 22 ]jF 10V

Semiconductors

Di r D2 = LED, 3mm, low current
T1 = BC850, HPN 45V transistor, SOT-23
IC1 = DS1338, real time clock, SOIC8
IC2 = PIC18F4520-I/PT, 8-bit MCU, programmed,
Elektor Store # 120637-41
IC3 = API 117E33G, LDO regulator, 3,3V, SOT223
IC4,IC5,IC6,IC7,IC8,IC9 = DS18S20, 1-Wire tem-
perature sensor, T092 (not on board)

Miscellaneous

Kbl = MCAK1604NBWB, keypad, 4x4 array,
Multicomp

XI = 32,768kHz quartz crystal, 12.5pF load, 20ppm,
4.1xl.5mm, Abracon ABS09-32.768KHZ-T
X2 = 8MHz quartz crystal, 18pF load, 20ppm,

5x3. 2mm, Abracon ABM3-8.00QMHZ-D2Y-T
Cardl - uSD {micro SD) connector, Hirose
DM3AT-SF-PEJM5(40)

BT1 = CR2032, with PCB mount holder
LCD! = DOGM162W-A 2x16 character LCD
Backlight EA LED 55x3 1-G
K1 = 6-pin pinheader, right angled, 0.1" pitch

K2 = 2-pin pinheader, right angled, 0.1" pitch
K3,K4,K5,K6,K7,K8 = 3-pin pinheader or socket, right
angled, 0.1" pitch

Socket strip 0,1" pitch, turned prns, for mounting LCD
and keypad
PCB # 120637

Figure 4,

The printed circuit board
designed for the project
contains chiefly SMD parts.

Internet References

[1] Thermo-Snake, Elektor June 2008,
www. etektor, com/070 122

[2] 1-Wire protocol:
http : //psychouLcom/
electronics/l-wire-onewire-cl8-library-2

[3] www,elektor ( com/120637

[4] Create a file of size xx:
http://windowsitpro.com/systems-manage-
ment/how-can-i-create-file-certainsize-win-
dows-xp-and-later

[5] PetitFATFs:

http : //elm-chan .org/fsw/ff/OOindexj. htm I

www.elektor-magazine.comi November 2013 31

Projects

By Michael Odenwald

(Germany)

Figure 1.

The USB thermometer
circuit is simple.

USB Thermometer

A simple method to read data from the USB port

For many years the serial RS232 computer port could be relied upon as a sort of
MacGyver universal port. Nowadays PCs are unlikely to be supplied with this 9-pin
sub-D connector. When you need to hook up some electronics to a computer,
the USB port looks like the only option. The computer however needs a
corresponding software driver. Here we describe an elegant patch around
this problem.

The development of a software device driver,
including adaptation to run in different operat-
ing systems, is anything but trivial. Add to this
also the niceties of digital signatures for which
the device/driver/operating system/application
program chain adds additional complexity. The
necessary time investment is often unacceptable
for small projects. For this reason a virtual COM
port is often employed but this brings with it the
(configuration) disadvantage and misses out on
many of the good USB features.

One USB mode that can be relied on to function
and also supports prototype development is the

USB-HID (Human Interface Device) class. The
USB HID usage allows many more devices than
just a mouse and keyboard (see The USB HID
device class'). The USB standard [1] specifically
allows the use of 'other devices' which Include
all types of actuators and sensors.

Since all of the major computer operating sys-
tems already have USB HID drivers there is no
reason why you shouldn't use them for your own
purposes. You only need to produce a suitable
application program to run in your computer's
operating system.

32 November 2D13 www.elektor-magazme.com

Measure temperature via USB

Data capture

You can use the USB HID pathway to pass all
sorts of external data to a PC. The temperature
measurement application is just one example of
the process. A small ATtiny microcontroller type
ATtiny85-20 {IC1 in the circuit diagram Figure 1)
is used here to provide the limited degree of
Intelligence' necessary to handle the USB pro-
tocol stacks, communications and also to input
and format the sensor readings.

All components in the design derive their power
directly from 5 V available at the USB socket
Kl. The microcontroller is clocked at 16.5 MHz
from its internal PLL, this gives enough speed to
handle USB communications and eliminates an
external crystal.

IC2 is the DS18B2Q temperature sensor from
Dallas semiconductor (now part of Maxim) which
uses a 1-wire interface. It operates in so-called
Parasitic Power mode [2] where the chip's VDD
pin is connected to ground and power is derived
from the data signal connection. This method has
the benefit of improving accuracy by reducing
the effects of self-heating in the chip. The USB
data signals are connected via limiting resistors
R1 and R3 which restrict current flow from the
line drivers in the event of a short circuit. The
two 3.6 V zener diodes D1 and D2 ensure that
the data signal voltage swing does not exceed
the chip's supply voltage.

Resistor R2 is used during USB enumeration
and signals to the host (in the PC) that a low
speed device (1.5 Mbit/s maximum data rate)
is connected.

Capacitors Cl and C2 provide supply decoupling
and buffering of the 5 V feed from the USB socket.
K2 is the standard 6-way ISP pin header to pro-
gram the controller. LED D3 indicates an active
measurement cycle. With the temperature sensor
at maximum resolution this takes around 750 ms.

Firmware

Firmware for the USB thermometer is written in
C, The WinAVR development tools [3] are used to
compile and burn the program to the microcon-
troller's flash memory. The USB stack structure is
implemented with the help of V-USB software [4].
Functions used to read the temperature sensor
are taken from a library by Martin Thomas [5],
After the hardware is initialized the USB soft-
ware stacks and USB enumeration process is
executed. The firmware then switches to inter-
nal operational mode where a state machine is

The USB-HID device class

The HID (Human Interface Device) device class is a partial definition
of the USB standards describing devices which provide input from
the user. Typical examples would be a keyboard, mouse or joystick.

In addition to these normal types of input devices the USB standard
also caters for 'special systems' which can take the form of sensors,
measuring equipment or even telephones or headsets. The use of
readers, games items and promotional products are also anticipated,
USB-HIDs have the benefit that the corresponding system driver is
already contained in the computer's operating system (at least for
Windows, Linux and OS X) and is therefore automatically loaded,
without any input from the user, whenever a new USB HID is
connected.

The disadvantages of HIDs should also not be overlooked: The data
transmission rate is not particularly high and they have a limited
number of USB Endpoints, restricting the amount of data which can be
transferred.

implemented. This Finite-State Machine consists
of; USB protocol, read the sensor and then wait.

The states are sequentially cycled with a pre-
defined delay period.

Each complete measurement cycle takes 10 s. The most important e | ement
Requests from the host within this period will in the firmware is the USB
return the same value, only after each cycle has HID Descriptor:

/*

* USB HID report descriptor
*/

PROGMEM char usbHi dReportDescri ptor [33] =

{

0X06 J

0X00 ,

0 xf f j

//

0X09 }

0 X 01 j

//

0 xal j

0 x 01 ,

//

0x15 j

0X00 ?

//

0 X 2 6 ,

0 xf f J

0X00,

//

0x75 ,

0X08 3

//

0x85 >

0X03 y

//

0x95 j

0X04 }

//

0X09 j

0X00 ,

//

0 xb 2 ,

0X02 ?

0X01 ,

//

0x85 j

0x14,

//

0x95 ,

0X03 j

a

0X09 ,

0 X 00 ,

//

0 xb 2 j

0 x 02 ,

0X01 3

//

0XC0

//

};

USAGE_PAGE (Generic Desktop)
USAGE (Vendor Usage 1)
COLLECTION (Application)
LOGICAL_MINIMUM (0)
LOGICAL.MAXIMUM (255)
REPORT_SIZE (S)

REP0RT_ID (10)

REPORT^COUNT (4)

USAGE (Undefined)

FEATURE (Data , Var , Abs , Buf )
REPORT_ID (20)

REPORT_COUNT (10)

USAGE (Undefined)

FEATURE (Data , Var , Abs , Buf)
END COLLECTION

www.elektor*magazine,com November 2013 33

Projects

Figure 2.

The PCB component
placement.

COMPONENT LIST

Resistors

R1,R3 = 68 Q
R2 = 1.5kQ
R4 = 470Q
R5 = lOkQ

Capacitors

Ci = lOOnF ceramic, 5mm pitch

C2 = 25pF 16V, electrolytic, 2.5mm pitch

Semiconductors

1C1 = ATtiny85-2GUP, 8-pjn DIL, programmed,
Elektor # 120620-41 [6]

IC2 = DS18B20, 3-pin T092 case
Dl,D2 = ZF3.6, zener diode, 0.5W
D3 - LED, green, 5mm

Miscellaneous

K1 - USB socket, Type A, PCB mount
K2 = 6-pin (2x3) pinheader, 0.1" pitch
PCB # 120620-1 [6]

elapsed will the latest measurement be avail-
able. The measurement process is controlled com-
pletely by the microcontroller and not by the PC.
The measurement interval helps reduce sensor
self-heating effects.

The Descriptor consists of 33 bytes. It defines the

possible report IDs (10 and 20), the application
program uses these to communicate with the
thermometer. The reports are implemented as
so-called 'Feature Reports' with different length
information blocks (4 and 10 byte). A feature
report allows values to be read from or written

The central class for the USB thermometer is then:

namespace WindowsApp

{

/// <summary>

/// Implementation of the usbDevice with service methods
iff based on the class usbGeneri cHidCommuni cati on
/// </summary>

class usbDevice : usbGeneri cHi dCommuni cation

{

private int tval;

/// <summary>

III Class constructor - place any initialization here
III </summary>

III cparam name=”vid”x/param>

//! < pa ram name= H pid"x/param>
public usbDevi ce(i nt vid, int pid)

: base(vid, pid)

{

1

III <summary>

III USB HiD Temperature Module Method GetTemeratur ()

III </summary>

public int GetTemperatur ( )

34 November 2013 www.elektar-magazme.com

Measure temperature via USB

to the USB HID system; in this application they
are only read.

Report ID 10 is used to request the temperature
and returns four bytes. Report ID 20 queries an
i dent string consisting of 10 bytes giving date
information (yyyy-mm-dd).

Build then drive

The circuit layout is not at all critical and the use
of non-SMD components with the PCB designed
for this project (see Figure 2) makes construction
really easy. The PCB layout hies are also available
for free download from the Efektor website for
this article [6]. Figure 3 shows the fully popu-
lated prototype. The design does not need any
set-up or calibration procedure.

Once all the components have been fitted and you
have double checked your handiwork the firmware
can be programmed into the microcontroller Seek
out the firmware which is freely available as both
a source code file and a directly programmable

hex file from [6]. Plug in your AVR-I5P program- Figure 3.

mer to connector K2 to program the device. It T ^ e thermometer

is important to check that the 'divide by eight' prototype.

dock divider option is deactivated and that the

correct internal clock is selected. The settings are

correct when the low fuse' has the vatue OxEl

// Declare an input buffer

Byte[] inputBuffer = new ByteTS]; // we expect 5 byte; 1 x ReportID and 4 Byte temperature

i nputBuf fer [0] = 10; // Read ReportID 10

// Perform the Read Command
bool success;

success - getFeatureReport (i nputBuf fer) ;

if (success == false)

{

Debug .WriteLine (“Error during getFeatureReport 51 ) ;

return tval; // Error during USB HiD_GetFeature Request so return the old value

}

tval = i nputBuf fer [T] << 24;
tval |= i nputBuffer [2] << 16;
tval |= i nputBuffer [3] << 8;
tval | - i nputBuffer [4] ;

return tval; // Return the new value

}

>

>

www.elektor-magazine.com November 2013 35

Projects

Figure 4*

Temperature displayed by
the application program
running in Windows,

Figure 5.

Temperature display using
the command line tool.

and the 'high fuse' has the value OxDD,

Once the microcontroller has been programmed
the circuit can be hooked up to the PC using a
USB cable. The operating system will detect that
a new HID device has been plugged in and will
automatically install the HID system driver; it's
that simple! It doesn't matter is you are using a
32 or 64 bit version of Windows, OS X or Linux,
the HID driver is always available, always digi-
tally signed and will always install without any
further input from the user, A couple of seconds
after plug-in the unit is ready to go.

|tv-nnd HRG

□

cJxhijnc\HiD Teftjtcrrature notiul\cnjl i '((njl>cFui“tqqr T ^xff —

LtiHj.it rrtl ure is: *1^.0625

c:\liontVH iD Tenperatupe HlodulScnri-tool>

Ld

values in the range -550,000 to +1,250,000,
The software divides these values by 10,000
giving a temperature value with a resolution of
12 bits or 0.0625 °C. This level of resolution is
not strictly necessary because the sensor itself
has an accuracy of only 0.5 °C. The screenshot
in Figure 4 shows how the temperature is dis-
played in Windows,

The Windows compliant source code together
with the necessary library is available to down-
load for free [6]. In addition to this Windows
based program there is a simpler command line
tool that returns the temperature reading as text
(Figure 5). The corresponding source code, com-
piled program and tool for Linux are also avail-
able from [6],

And so it goes..*

The circuit and corresponding software for the
USB thermometer demonstrates a simple and
practical method to connect your own HID device
to a PC, Both can be relatively easily adapted
to the needs of your own particular application,
giving an (almost) hassle-free pathway to pass
data to a PC providing you do not have too much
data to send and can accept a relatively mod-
est data rate,

(120620)

The host software

The (Windows) application program which inputs
and displays the USB thermometer readings Is
written in C#. It demonstrates how communi-
cation with a generic HID device Is performed.
The host software uses the usbGenericHIDDevice
functions in the library [7], which interacts with
the Windows API functions. The software is com-
piled and run using the express version of Visual
Studio 2010 [8], The base class usbGenericHid-
Communication is key here, from which a class
for our own HID device must be derived. In this
class the 'method' to be executed is implemented.

The HID device is identified and called with the
parameters Vendor ID = 0x0C7D and Product ID
- 0x0011. The method GetTemperaturQ reads
and returns the temperature value. The tempera-
ture range of the sensor spans -55 to +125 °C.
The sensor sends measurements formatted
according to 'signed longint' convention giving

Internet Links

[ 1] www.usb.org/developers/hidpage/

[2] http://datasheets.maximintegrated.com/en/
ds/DS18B20,pdf

[ 3 ] http : //wi na vr, sourceforg e , n et/

[4] www.obdev.at/products/vusb/index, html

[5] www,siwawi,arubi,um-kl,de/avr_projects/
tempsensor/index, html

[6] www, elektQr.com/12Q620

[7] www, waitingforfriday. com/index, php/Open_
Source_Framework_for_USB_Genenc_HID_
d e v i c es_ b a sed _o n_th e_Pl C 1 8 F n d _ W i n -
dows

[8] www, microsoft.com/germany/express/prod-
ucts/wfndows,aspx

36 November 2D13 www,elektor-magazine.com

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i r

DESIGNSPARK PCB

1

DesignSpark
Tips and Tricks

Day #5:

generating PCB manufacturing files

By Neil Gruending (Canada)

Today we will generate the Gerber files
and BOM information for the design
we laid out last time. DesignSpark has
excellent support for generating these
types of files once it's been configured
properly.

Figure 1,

Data to be included in the
Gerber output file.

Gerber Outputs

Gerber files are the file format needed by a
printed circuit board (PCB) manufacturer to actu-
ally manufacture a design. Think of it as a simple

vector image format of the PCB using different
size pens (apertures). Gerber fifes are commonly
referred to as plot files because they Ye used by
a photoplotter as part of the circuit board man-
ufacturing process.

DesignSpark can generate Gerber files from the
"Output Manufacturing Plots" window, which is
opened from the Output- > Manufacturing Plots
menu. In our case we need the Top Copper, Top
Solder Mask, Top Silkscreen, Bottom Copper,
Bottom Soider Mask, Drill Data and Drill Ident
Drawing plots as shown in Figure 1.

Clicking on the Options button will open the
Options windows where you can modify all of
the settings for Gerbers, drill file and PDF outputs.
I personally like to use R5-274-X to embed the
aperture information into the Gerber files, and to
export everything in metric with four decimals of
precision as I've illustrated in Figure 2.

Clicking the RS-274-X button will adjust the listed

38 | Movember 2013 ] www.elektor-ma gazine.com

Tips & Tricks

options to enable the embedded aperture table
and clicking the RS-274-D button will disable all
of the output options.

Circuit board manufacturers also need a drill file
or NC (numerically controlled) to know where
to drill the holes in the circuit board. There are
several different output formats but I personally
like to use a metric Excellon format with four
decimals of precision, as illustrated in Figure 3.
Now that we've configured the output devices,
we need to add the board outline to all of the
generated plots so that the circuit board man-
ufacturer can line up all of the different layers
when making the RGB, You do that by clicking on
the Layers tab for each plot in the Output Man-
ufacturing Plots window, and double clicking on
"[Board Outline]" so that a Y is displayed in the
Selected column.

Once the board outline is added to all of the layer
plots, click the Run button to generate all of the
output files. After the files have been generated,
DesignSpark will display a report summary in
Notepad, which you should review to make sure
that there weren't any errors. All of the Gerber
files will have a .GBR extension, and the drill files
will have a .DRL extension, I always toad the Ger-
ber and drill files Into a 3 rd party Gerber viewer
like ViewMate [1] just to make sure that there
aren't any errors. For example, white writing this
article I had accidently set some incorrect scaling
factors in the Gerber output that became obvi-
ous in the Gerber viewer, and were easy to fix.

Figure 2,

Selecting metrics with
4-decimal accuracy.

Figure 3,

Four^decimaf precision is
also defined for the NC drill
data.

Bill of Materials

A Bill of Materials (BOM) lists all of the compo-
nent information in a design so that it can be
manufactured, DesignSpark includes the ability
to generate BOMs as part of its Reports feature
in the Output menu, as shown in Figure 4.

The built-in Bill Of Material report will generate
a BOM with the following fields:

• Ref Name: The reference designator for the
component

• Qty: The number of components for that
line, always 1

• Component: The component name field
■ Value: The component value field

• Package: The component PCB footprint type

• Manufacturer: The component manufacturer
field

• MPN: The component manufacturer part
number field

Built-in Reports

BJ Of Materials

Dangtng Trades
Design status Report
Generic Nefcst
Schema tic^PCB Check
Unconnected Pns Report
U$er Reports
BiP Of Materials

I I

Close

Options,,.

Hew...

Qspy...

RcnaMfe*

Effete

Figure 4,

Selecting the BOM as a
Report.

www.elektor-magazine.com [ November 2013 | 39

Figure 5*

Editing options for the BOM
report generator.

Figure 6*

One way of composing the
BOM.

* RS Part Number: The component RS part
number field

• Description: The component description field

The default BOM is fine if you only have one
part number per component, but I tike to asso-
ciate alternate part numbers to the component
so that my BO Ms have ail that information avail-
able automatically. I also like to see the same
part grouped together instead of a line for each
component. For example, I find it better to know
that there are two 1 K (kft) resistors in a design
instead of having to count them manually in the

BOM, Unfortunately DesignSpark cannot group
components together on a BOM and display their
reference designators in the same report, which
means we will have to create two custom BOMs—
one that Is grouped for purchasing and another
with reference designators for assembly.

The first step is to create a new report by click-
ing on the New button. A dialog box will pop up
where you can give the report a name, and then
you will be able to edit the report content. It will
look like In Figure 5.

What's happening here is that the first line in the
report will be the text "Component Report", fol-
lowed by Design Spark's standard report header,
a blank line and then a list of all the components.
The part we have to edit is the Component List,
For the purchasing BOM I edited the report col-
umns to be Qty, Description, Manufacturer 1,
Manufacturer 1 Par Number, Manufacturer 2,
Manufacturer 2 Part Number, Manufacturer 3
and Manufacturer 3 Part Number. The assembly
BOM is the same as the purchasing BOM, except
that it includes the reference designators or Ref
Names in DesignSpark. Figure 6 shows the con-
figuration I use for assembly BOMs.

To add custom report columns like Manufacturer 1
to your report you need to choose Value from the
Field dropdown box. This will enable the Values
box where you can select one or more component
fields to be used for the column. The Caption field
will be the column heading in the final report. It's
also important to run the BOM reports from the
PCB file and not from the schematic— to make
sure the BOM is populated properly.

Conclusion

Today we generated Gerber files and a BOM from
our DesignSpark design enabling it to be man-
ufactured. Next time well look at some of the
online quoting tools built into DesignSpark*

(13C24Q)

Internet Reference

1* www.pentalogix.com/viewmate.php

40 I November 2013 | www.elektor-magazi ne.com

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elektor apcircuits.com

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4 “

The Problem

You've got intermittent pulse bursts
being generated when they
shouldn't be. You can see them on
a scope. Mow often and when are
they occurring?

Or you just want to know what is
happening in a longer time period

The Solution

Use a Cleverscopel
Capture a day's
worth of samples
at 1.5 MSPS. Pan
and zoom, really
quickly. Accurately
identify when
events happened.
See even very
short ps events in
a day's recording.
Check out
http://youtu.be/

67TU2NAaHGg

CS328A-XS

1 4 Bit MSO

rscope.com

•km 1

<w 1

— r

i i

HI II

Hll

\

i i

LJ

i ■ i

u

[~T f

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Projects

Bidirectional
Stereo Input Selector

1-4 or 4-1

Following a recent appeal*
made in the magazine calling
on our readers to send us
their own circuit designs— if
possible simple and prefer-
ably in fields that receive
less coverage in Eiektor, like
audio, for example— we re-
ceived this suggestion which
meets the two main criteria;
uncomplicated and intended
for processing sound signals.

By Olivier Croiset

(France)

In this era of the microcontroller heavily domi-
nating the electronics scene, a circuit like this one
may seem pretty simple, simplistic even—but it
does have the undeniable merit of not frighten-
ing off someone just starting out in electronics!
What's more, it lends itself to all sorts of modi-
fications, particularly to extend the possibilities
or adapt it to specific needs*

A good opportunity for beginners to stray from
the beaten track, beginning with a circuit that's
sure to work. The idea arose out of a practical
need I had at home: repairing the faulty input
source selector switch on my amplifier— a well-
known and often thorny problem. These multi-
way selectors are not usually standard types,
and so are almost impossible to find.

With this little project I'm suggesting, I was also
keen to reduce audio wiring (even screened), so
as to keep it simple and above all minimize pos-
sible sources of interference.

Not for microcontroller fans!

The version of the diagram in Figure 1 has been
reworked and improved in the Eiektor Labs and
then redrawn in accordance with Elek tor's house
style for schematics. My original version was
drawn using the DesignSpark PCB application.
On the left, four buttons (one per channel) Sl-
S4 are associated with four diodes (D1-D4) to
form a logic OR function. The output of this quasi
logic operator is the common point of the four
cathodes. This goes high when one of the buttons
is pressed. This controls the clock (CLK) input

* this appeal is still open: your original contributions are welcome in the magazine, Put them on line on our community website www, eiektor- labs, com; the
authors of suggestions Laken up by the editorial Staff will be contacted with a view to selling up a publication contract.

42 November 2013 i www*elektor“m3gazine,com

4—1 / 1—4 Audio Selector

a trouble-free audio add-on, suitable for beginners

Figure 1, The audio source selector circuit is not directional: designed for four stereo inputs and one output,

it can perfectly well be used the other way round*

www.elektor-magazine.com' November 2013 43

Projects

Figure 2 ,

The two outputs are
distinguished by using two
black sockets for the L and
R channels, while the four R
inputs use a red socket Tip:
note how the indicator LEDs
are kept straight using the
cylindrical spacer on which
they are mounted.

common to all 1 four D-type flip-flops in IC2, a
74HC175. Each time the CL K input goes high, the
flip-flop Q outputs adopts the logic level present
at this moment at their data input D (IC2 pins
4, 5, 12, and 13), When the button is released,
the CLK input (pin 9) is immediately taken low.
However, nothing happens, as the flip-flops only
react to rising edges on the CLK input.

Pressing one of the channel selectors S1-S4 also
takes the D input of the corresponding flip-flop
high* The corresponding Q output (pins 10, 7,
10, and 15) likewise goes high. We are now in
the right-hand part of the circuit diagram. The
Q output of the triggered flip-flop in turn drives
one of the transistors T1-T4, which turns on and
activates the relay Rel-Re4 in its collector cir-
cuit, In this way, one of the audio signal channels
is selected (lower part of the circuit diagram in
Figure 1). The LED corresponding to the active
channel (D5-D8) lights.

The snubber (back-emf) diode shown to the right
of each relay is not a separate component, but
is included within the device. Its function is to
protect the transistor from the voltage spike that
appears on the relay coil when it is de-energized.
On the left, we have four left and right pairs of
stereo signal sources (Left 1-4 and Right 1-4)
and on the right a stereo output (LeftOut and

RightOut),

Do note that even though we are referring to
'input" and 'output', this is no more than a con-
vention, since the circuit can perfectly well be
used in reverse, with one Input (LeftOut and
RightOut) feeding four sound equipment inputs
(Left 1-4 and Right 1-4).

So what do you think happens if you press two
buttons at once? Nothing, because the flip-flop
outputs only adopt the logic level of their D input
when there is a level change (rising edge) on the
CLK input. So once a button is pressed and not
released, this CLK input is kept high. There's no
rising edge, so the flip-flops don't react.

At power-up, the CLR input to the four flip-flops
is kept Low while C4 is charged through R23*
In this way, the flip-flop Q outputs are forced
Low, regardless of the level of their D Inputs. At
start-up, the four relays are always de-energized,
only the indicator LED D13 is lit.

Among the possible variants of a circuit like this,
we can note that depending on whether the tran-
sistor is driven from the flip-flop's Q or Q out-
put, we can energize just one of the relays, as
we are doing here, or all but one of the relays.
The latter option is not catered for on the PCB
as proposed here*

44 November 2013 i www.elektor-m 3 ga 2 ine.com

4—1 / 1—4 Audio Selector

R i g h t I

La f t I

5 0 - 6 0 Hz.
CONN 1

•

S4

•

4

Figure 3 .

Stereo channel selector PCB
design. There's no need
for a heatsink on voltage
regulator IQ, but there
would be space to fit one.

Selection, a sound trap

To make this stereo input selector easier to
build, Elektor Labs have redesigned a single
(superb) PCB using Design Spark, although I had
originally planned on two separate boards; this
makes it possible to have the relays and inputs/
outputs some distance away from the buttons
and LEDs, to which they would be connected
using ribbon cable.

In this instance, we have a sort of remote control.
It's debatable; both options have their drawbacks.
In any event, even though my original config-
uration has not been adopted by Elektor Labs,

I'm pleased that my little circuit is being pub-
lished, and what's more as a "normal" article— I
was only expecting it to get a quarter page in a
Summer issue!

The circuit here is powered from the AC powerline,
using a transformer for which both the safety and
signal track spacings have been respected. How-
ever, if you have stricter requirements as far as
electrical safety is concerned, and the presence
of the transformer bothers you, it can be fitted
away from the PCB, or even done away with alto-
gether by powering the selector from batteries,

(120316)

COMPONENT LIST

Resistors (,25W, 1%):

Semiconductors

R1,R7,R9,R11,R18-R21 = 100ft

D1-D4 = 1N414B

R2-R5 = !.2kft

D5-D8,D13 = LED, 5mm, yellow

R6,R8,R1Q,R12 = 390ft

D9-D12 = 1N40O4

R13-R17 = Ikfi

IC1 = LM7805CT

R22 = 560ft

IC2 = CD74HC175E

R23,R24 = lOOkft

Miscellaneous

Capacitors

FI = fuse, 500mA, fast

Cl = 0.1 pF 100V, ceramic disc

K1-K10 = RCA (line) audio socket, PCB mount

C2 = lOjjF 100V electrolytic

Rel-Re4 = relay, DIL, PCB mount, e,g. MEDER type

C3 = lGOOpF 25V electrolytic

DIP05-2A72-2ID

C4 = IpF 63V electrolytic

S1-S4 - pushbutton w. make contact

CS = lOpF 100V, ceramic disc

TR1 = power transformer, secondary 9V @ 2VA

www.elektor-magazine.com 1 November 2013 45

Projects

LED Lighting
For Model Buildings

Modular, PC controlled on a
serial link

8y Kurt Zerzawy (Switzerland)

This small module has been designed to individually control
five LEDs used to illuminate model buildings. The control
signal is sent over a single wire from a PCs RS232 serial
port. The design allows for up to 250 modules to be
controlled by a single PC, that's almost enough for
a small town!

Even if you only have a modest model train lay-
out at home, the chances are that it will have a
station and some other buildings. Rather than
switching all the house lights together, it gives
a much more realistic appearance if the lights
can be individually controlled. In reality the light
pattern changes as occupants move from room
to room. The serial control module achieves this
while avoiding the dreaded cabling rat J s nest.
Its modular design allows you to start small and
easily add more modules as the Layout gets more
ambitious,

Cutting costs

The circuit does not need to perform any demand-
ing tasks—for this application the main design
criteria are the module's size and cost. In fact
the circuit shown in Figure 1 consists of little
more than a small 8-bit microcontroller and a
voltage regulator. The microcontroller is a small
8-pin P1C12F675P from Microchip, in a DIP outline
which can be found for not much more than a
dollar. It contains a 1 KB program memory, 128

bytes of EEPROM and (essential for serial com-
munication) a timer/comparator. The EEPROM
is used to store the module's address. All of the
pins can be defined as I/Os (except the supply
pins naturally), the internal oscillator is used to
supply the system clock. Download the data sheet
[1] to find out more about the chip.

The anodes of the five LEDs for each module
are wired to the PCB-mounted terminal blocks
K1 and K2 which connect back to I/O pins GPO
to GP2, GP4 and GPS on the controller chip. The
cathodes of all the LEDs are connected together
to pin 3 of connector Kl. The 1-kft series resis-
tors limit the forward current through the LEDs
to safe levels. The current will be dependent on
the type and color of LED used here. The forward
voltage drop will typically lie somewhere between
1,9 and 2,5 V resulting in a current between 2
and 2.5 mA. It is important to use low-current
LEDs here in order to achieve full illumination
from just 2 mA supply current.

The LEDs are switched on and off by information
contained in the signal received over the serial
interface (via pin 1 of K3). This works essentially
as an RS232 interface using just the receive signal
(RXD) connected in parallel to all modules. The
level shifter network D1 and T1 limits the ±12 V
signal from the PC to +5 V at each module's input.

46 November 2013 i www.elektor-magazi ne.com

Serial Programmable LEDs

Voltage regulation is performed by a 78L05
regulator which is good for up to 100 mA. The
'usual suspects' can be seen lurking around this
IC: capacitor C4 and the two 100-nF capacitors
Cl and C2, The circuit can be powered from
an unstabilized power adapter with an output
between S and 12 V DC. The simplest option is
to use a power adapter connected to K3. Each
module requires just IS mA, so it is possible
to power a lot of modules from quite a modest
adapter. When a really large number of modules
is used it would be sensible to power them all
from an external power adapter providing a stabi-
lized 5 V at the necessary current. The on-board
voltage regulator can then be left out of the cir-
cuit, replaced by a wire link between the input
and output pad.

The pinheader strip J PI is for the connection to
a microcontroller programmer. It is not neces-
sary if the PIC has already been programmed
(or has been bought pre-programmed). Pro-
gramming each module's address occurs over
the serial interface and does not require this
interface. The pin assignment of connector jPl
is given in Table 1 which conforms to the Pickit2
[2] ISP programmer connector. During the pro-
gramming procedure it is important to ensure
that the chip is powered either from its on-board
supply or from the Pickit2 programmer, not both
at the same time!

Table 1* The Programming Adapter JPl

JP1

PIC12F675

Signal

Pin 1

Pin 4: GP3/MCLR

Vpp

Pin 2

Pin 1: VDD

+ SV

Pin 3

Pin 8: VSS

GINJD

Pin 4

Pin 7: GPO/ANO/icspdat

Data I/O

Pin 5

Pin 6: GPl/ANl/icspciock

CLK

Pin 6

—

—

Communicating with the module

The serial interface is used to send switching
information to the LEDs and also to assign an
address to the module.

During power up the module uses its LEDs to indi-
cate if it has already been assigned an address:
when all five LEDs briefly come on together then no
address has been assigned, when they switch on
in a sequence one after the other then the address
has already been assigned. Seriaf communication
occurs over the RS232 interface at 9600 Baud, no
parity, 1 stop bit. These communication parame-
ters can set up in the terminal emulator program
on the PC. In HyperTerminal (Windows) select File/
Properties/Configure to make the changes.

Module addressing

To assign an address to a module and store it
in the PIC's internal EEPRGM enter the follow-
ing sequence:

R5232

Ho
4o

-o

SUB D9

□

*

13

+S...12V

©-

(§>

GND

K3

IC2

I®! 1 -

i

1 4

C4

—

C2

[ ] u

78L05

0 *

lOOu

25V

Cl

R1

-) took L

L

C3

IDDp

IGOri

D1

ESAT85

a o

o o

□e ■=- a. il.

d f = si ^ *

E ^ £ § y J

u □ (fi

£

uj W W □

S “ O ^

JP1 Q Q O Q Q

1

H9

OR

ta

©

ESC 548

£

5 1 B

|rs

u

vacs

GP3WCLR GPQiANO
GP1/AN1
GF2fAN2
GPJ/AN3
GPSi'CLKIW
VSS

S

PIC12F575P

K2

R3

R4

- | Ik

R5

rDi

H

4 +

M

4 +

130136 - 11

Figure 1,

The LED control module
schematic.

www.elektor-magazine.com 1 November 2013 47

Projects

COMPONENT LIST

Resistors

R1 = lQOkQ
R2-RS = lk Q
R7 = lOkQ
R8,R9 = OQ

Capacitors

C1,C2 = lOOnF
C3 = IDOpF
C4 = lOOpF 25V (e.g. Rubycon
25YXF100MEFC6,3X11)

Semiconductors

Dl ^ BATS 5
T1 = BC548

IC1 = PIC12F675-I/P (Microchip), pro-
grammed, Elektor Store # 130136-41
IC2 = 78 LOS

Miscellaneous

JP1 = 6-pin pinheader
Kl,K2 r K3 = 3-pin PCB screw terminal
block

PCB # 130136-1 [3]

'y' : Hex address low byte of the selected house
y = 0 to F

'S': Command S for set

'a': High byte of the selected LEDs (0 or 1)

'b' : Low byte of the selected LEDs (0 to F)

'CR': Carriage Return (enter) to end the sequence.

The input sequence is therefore HxySab followed
by 'enter", where xy is the addressed module, J 5'
represents set and J ab' is the hex value of the
LEDs that will be turned on* This value can be in
the range 00 to lFh, allowing every combination
of the five LEDs to be switched.

Example: To turn on LEDs 3 and 5 of module
12, enter the line H12S14 followed by 'enter' at
the terminaL

Figure 2 *

Thru-hole components but a
tidy layout nevertheless.

J H": House

'F': Hex address High- Byte (F for un prog rammed
chip)*

T': Hex address Low-Byte (F for unprogrammed
chip)*

'P': Command P for programming.

'a'

'a'

"5": Safety code required to prevent accidental
programming.

'5": Safety code required to prevent accidental
programming*

'x': High byte (Hex) of the address to be assigned
to the module, x = 0 to F.

'y r : Low byte (Hex) of the address to be assigned
to the module, y = 0 to F.

'CR': Carriage Return to terminate the sequence.

Entering the sequence 'HFFPaaSS' at the termi-
nal will cause the chip to switch on all the LEDs,
Enter next the desired address (xy) and finally
the 'enter' key. The LEDs will now go out and
after an off/on power cycle the address will be
stored. The same sequence can be used at any
time to assign a different address to the module.

Example: To allocate the address 23h to a module
that has not yet had Its address assigned , enter
the sequence / HFFPaa5523 / followed by 'enter'.

Switching LEDs

Controlling the module
'H f ; House

V: Hex address high byte of the selected house
x = 0 to F

Build it modular

Figure 2 shows the PCB for a single module which
can be ordered from Elektor* The use of thru-hole
components simplifies construction greatly. The
two 0 Q resistors R8 and R9 are necessary to
bridge some PCB tracks and can be replaced by
wire links. Use a socket to mount the controller*
All the modules are connected in parallel. Resis-
tor Rl in each module ensures that only a very
small amount of current is taken from the RXD
signal, allowing a large number of modules to be
connected without any problem* The RXD signal
is generated from pin 3 of the 9-way sub D con-
necter on a PC. The earth connection is on pin 5
of the same connector and is linked to the earth
wire in the power cord*

The pre-programmed microcontroller reference
number 130136-41 can be purchased from the
Elektor Store. Alternatively you can program the
chip yourself if you posses the programming tools*
This option is more attractive if you have a large
layout requiring many modules* The software is
free to download from [3] and includes all the
CAD files for the project, viewable using the free
CAD program DesignSpark.

(130136)

Internet Links

[ 1 ] wwl .microchip.com/downloads/en/DeviceD-
o c/4 1190G.pdf

[2] www.microchip.com/pickit2

[3] www.elektor*com/130136

48 November 2013 i www.elektor-magazi ne.com

Throw off the 8-bit ball and chain!

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* deep. 12 8/2 56MB * USB/UART/$P!/I^C - GxADC/BxPWM/CAN

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Labs

By Clemens Valens

(Elektor.Labs)

Some people have sound and/or stimulating ideas but do not know how to translate
them into working electronic circuits, while others lack the skills and/or the time to
complete a project. Below is selection of projects posted on Elektor.Labs and looking
fora helping hand to reach the finish line. Can you cheer and/or assist?

Electronic Sculpture

Original Poster (OP) snap wants to create an electronic sculp-
ture capable of producing figures in 3D by individually moving
up and down some fifty balls attached to strings. There are
some nice videos on YouTube showing such contraptions, just
search on "'BMW kinetic sculpture" or words of similar mean-
ing. Winding and unwinding the strings can be done with small
motors, but how do you control fifty of them in a synchro-
nized way without spending too much money or time? The
weight of it alt is an important factor too. The OP is looking
for help; do you have experience with a similar project? Are
you confident with electronics, motors and mechanics? If so,
why don't you surf over to www.elektor-labs, com/node/3450
and post a contribution.

Photo: BMW Welt

Five Cool Projects

Outdoor Solar Wireless Wi-Fi/ 3G Webcam

www.elektor-labs.com/node/3538

All-You-Can-Eat Bluetooth

www, elektor-labs.com/node/3032

PWM Controller For flashlight

www.elektor-labs.com/node/3537

RS-485 Sniffer

www.elektor-labs.com/node/3S22

Mouse-Friendly Mousetrap

www, el ektor-labs.com/node/3433

50 November 2013 wwvv.elektor-magazi ne.com

elektor

labs

GMR-based Current Probe

Measuring current with a multimeter is easy; doing the
same with an oscilloscope is a bit more involved. You
0 can of course buy special current probes, but they tend
to be expensive, which is why OP RolandSautner decided
to design his own. Unexceptional current probes use Hall-effect sensors and AC
transformers to measure DC and AC currents, but the OP wanted to use another
method: giant magnetoresistance, or GMR, Why? Because he had an unused KMZ51
magnetic field sensor lying around and felt that it was a shame not to use it* The OP got pretty far, but finally
encountered some problems mainly related to mechanics. Can you help the OP to transform his design into a prac-
tical probe? If you can, please go over to www.elektoHabs.com/nQde/3423 and post your ideas and suggestions*
Photo: Agilent

Frequency Inverter

This is about a project that has my personal interest, but I've never gotten round to
building one* As always, I am not alone as I saw OP PappaBaer ' s post. A frequency
inverter or, to be more correct, a variable-frequency drive (VFD), is a device that can
control the rotation speed of an AC motor— usually three-phase, Elektor has published
such a device in 1994/1995. The project was very successful right up to being recalled
again in Retronics in 2006, but it never saw a successor. The components used in the
original design are now hard to find or even obsolete, and a redesign would be welcome.
This time with open-source software, of course. Have you ever been involved in such a

project? If so, please join us at www.elektor-labs.com/node/3484.

Photo: Wikipedia

www.elektor-labs.com

Trailer Reversing Lamp

One of the great things about Elektor. Labs is the wild
diversity of the projects posted. There are lots of
things to discover thanks to the different interests of
the authors. Some time ago PLEG54 posted a project
to develop an adapter for old vehicles allowing them
to pull modern trailers sporting a reversing lamp or
back-up light, ECE regulation R48 imposes this, ECE-
R48? I did some research and discovered The World Forum for Harmonization of Vehicle Regulations. This is a working party
of the Inland Transport Division of the United Nations Economic Commission for Europe (UNECE), assigned with creating a
uniform system of regulations for vehicle design to facilitate international trade* Regulation R48 concerns the installation of
lighting and light-signaling devices* This means that the UN decides which lights and reflectors you need to have on your car
and trailer, and where. Anyway, this is all very instructive, but the really interesting part is that the OP is stuck and can use
some help. You can find him or her at www*elektor-labs. com/node/3360.

Photo: Wikipedia

Note: OP stands for Original Poster the person who started an online project or discussion, OPs who want to have a chance of appearing in Elektor Maga?ine

must (regularly) check the email address they use to access Efektor.Labs, This is our only means of contact.

www.elektor-magazine.com November 2013 51

Labs

Power your circuit with better software

By Clemens Valens

(Elektor.Labs)

Often a lot of time and energy is spent on designing an elegant, well-thought-out
and robust circuit. Today, the brains of many of those circuits is a microcontroller
that needs software to function. Is it unreasonable then to expect a well-designed,
properly written program to make such a quality circuit work? Apparently it is.
Let's talk software quality.

It is a well-known fact: bugs kill people and soft-
ware bugs are no exception. Every year people die
because of failing software. Some fatal airplane,
helicopter and car crashes can be attributed to
software problems; malfunctioning medical device
firmware make victims on a regular basis; build-
ings go up in smoke due to bugs, and some peo-
ple get hacked to death. Bad software can even
sink boats. Believe me, I have seen it happen.

A bug-free piece of software doing a meaningful
job does not exist. According to Wikipedia, NASA's
Software Assurance Technology Centre has man-
aged to produce software with less than 0.1 bugs
per 1000 lines of code, which is considered to be
extremely good. Commercial organizations do
not have the time and money to achieve such
a level of quality. Apparently Microsoft tries to
be at 0.5 bugs per 1000 lines when it releases a
new product, so realizing that Windows XP was
compiled from 45 million lines of code, you know
that it contained more than 22,500 bugs when
it was released. It is estimated that programs
written in industry for internal use have error
rates from 5 to 50 bugs per 1000 lines.

Software defects— a more official term for 'bugs'—
can have many origins, from badly understood,
complex problems to downright sloppy program-
ming. Contrary to popular belief, making good
software is not easy as it demands extreme pre-
cision and care. For every line of code that must
be written, at least three things are required:

1. a good understanding of the problem and
its solution that the line of code is sup-
posed to implement;

2. the capability of expressing this solution
correctly in the programming language at
hand;

3. not making any typing errors while enter-
ing the code.

The first point is often the hardest part, espe-
cially for large projects. This is why skilful system
architects and good specifications are essential
to the success of a project.

Item 2 is afso a difficult one as it involves the
choice of the programming language— not every
language is suitable in every situation— and
expressing togic reasoning in a non-natural lan-
guage without making mistakes.

The third point seems moot, but is actually pretty
hard to get right. It is very easy to miss a brace
or a bracket, swap two symbols or mistype a
character. It is only at this point that the pro-
gramming tools start helping the developer and
only by pointing out syntax errors and maybe
compatibility issues and other conflicts between
data objects.

To reduce the risk of creating future defects due
to our line of code, we can add to the list:

4. make sure the code ts written in a dear and
understandable way;

5. add comments (and keep them up-to-date)
to explain the reasoning behind the line of
code;

6. adhere to a coding standard.

Item 4 refers to the use of comprehensible
names for functions and variables* Although it
may require more typing, a variable name like

52 November 2013 www.elektor-magazi ne.com

Windows XP was compiled from 45 million lines of code
on release it contained more than 22,500 bugs

"acceleration" is much more explicit than "acc"
or just "a".

Item 5 is ignored by many programmers. Not
because they are not aware of the comment fea-
ture of the programming language they use, but
because they are too lazy to use it.

The last point is a very important one. Many
amateur programmers are not remotely aware of
coding standards, while some professional pro-
grammers are, but don't care.

get.sample () is called and the value it returns is
assigned to the variable sample* Now the Boolean
if statement will check if the condition between
its parentheses is true or false. In C/C++, false
equals 0 and true equals not false. Therefore, if
sample is non-zero, the condition is considered
to be true and the addition will be executed*
But maybe the programmer intended this:

if (sample"get_sample£) ) sample += 2;

But what Is a coding standard?

Most software producing companies have house
rules or conventions on how their developers
should write code. On the internet you can find
coding standards for many open source projects
like GNU CU or Linux, However, most of the ti me
these rules are limited to the formatting of the
source code, and their goal is to create uniform
source code which can be maintained more eas-
tly. Since they concern mostly the appearance
of the code, it is better to speak of a coding or
programming style,

A real coding standard is not a set of rules to
make your program look pretty; it is a set of
rules to reduce programming errors. It may also
be used to achieve compliance with a regula-
tory standard. Because today C and C++ are the
prevailing programming languages, most coding
standards address C/C++, The advantage of con-
forming to a standard is that you can use static
analysis tools to check the semantics of your code
instead of only the syntax, which helps you to
identify possible issues a compiler cannot fnd.
So, what kind of rules can you expect from a
coding standard? Here are a few examples:

Ban explicit language features that can hide
coding errors

In C and C+ + , it is legal to do use the assign-
ment operator ' = ' in Boolean expressions. For
example, the following expression is legal:

if (5ample=get_sample () ) sample += 2;

This line of code will add 2 to sample if sample
is not equal to 0. Why? Well, first the function

The difference, an additional ' = ' character, is
subtle. In C/C+ + , the sequence " = = " means
"is equal to". So, the value of 2 will be added to
sample only if the value of sample is equal to
the return value of the function get_sample().

This is dearly not the same behavior as before.

Is this a programming mistake or was it intended?
Impossible to know. Some compilers can flag
this issue, but only if the warning is activated.

This is why a coding standard bans this kind of
language features*

Year 2000, Y2K or Millennium bug (1999)

Due to the practice of abbreviating a four-digit
year to two digits, many programs risked to
calculate wrong dates after 1999. Huge
efforts were made to prevent the
bug from biting, Worldwide costs are
estimated at a whopping 425 billion
dollars, but in the end nothing serious
happened. Something similar may
happen on the 19 th of January 2038
when the UNIX seconds counter will
overflow,

Only use initialized pointer expressions

This is a classic pitfall and the cause of in numer-
ous bugs. When a pointer to a data object is not
initialized— he, a 'wild' pointer— it can point to
anything. Using such a pointer will result in unde-
fined behavior of the program. Again, some com-
pilers can flag this issue, but only if the warning
is activated* Forbidding the use of uninitialized
pointers is the only solution* Because pointers

www.elektor-magazine.com November 2013

53

1

Labs

Ariane 5 Flight 501 (1996)

A complete loss of guidance and attitude
information 30 seconds after lift-off due
to specification and design errors in the
software of the inertia I reference system
caused the satellite launcher to disin-
tegrate. The origin of the crash was a
64-bit floating point value that did not fit
in a 16-bit signed integer, resulting in an
overflow. The unexpectedly high value
was calculated by an algorithm designed
for the Ariane 4. Financial loss was esti-
at some 400 million dollars.

are dangerous, some other programming lan-
guages restrict their use.

Pointers are closely related to buffer overflows,
number 3 in the 2011 CWE/SANS Top 25 of most
dangerous software errors (that deals mostly
with code security issues)

int* p_some_poi rcter ;

p_5ome_pointer = address_of_data_obj ect ;
p_some_pointer [34] = 3;

Although in the above code fragment the pointer
Is initialized before being used, one question

A8658t-6&

SX837

iny

Pentium™

■PROCESSOR

Intel Pentium Floating-
point Divide (1993)

A design error in Intel's
brand-new Pentium micro-
processor causes small errors
when floating-point numbers
that occur within a specific
range are divided! Although
the bug affects few users, it
becomes a public relations
nightmare and ultimately
costs Intel some 650 mil-
lion dollars,

remains: is the index of 34 valid? If not, it is a
buffer overflow error.

Strong data typing

In C/C++, variables of one type can be assigned
to variables of another type as long as the new
data type has the same or better precision. For
example, assigning an integer variable to a float-
ing-point variable will not produce a warning.
Going the other way may generate a warning.
This means that for instance a character rep-
resented by an 8-bit value can be added to a
32-bit floating-point value; the compiler takes
care of the conversion. To prevent adding pears
and apples, a coding standard will forbid the pro-
grammer to mix data types unless an explicit
type cast— changing a data type into another— Is
provided, like so:

float a = 3*14;
int b = (i irt) a ;

Eliminate unused or unreachable code

Normally ail code lines of a program have a
function. However, it can happen that, due to
a programming error, one or more parts of the
program become unreachable because the exe-
cution path to those parts is cut off. Take this
Arduino sketch:

void setup (void)

{

int a = - 1 ;
unsigned inf b - l;

if ( a < b ) a +- 2 ;

Seri al , begi n ( 115200) ;

Seri al , pri ntln (a) ;

1

void loop(void)

{

}

What value will the serial monitor print for the
variable a? “1! Why? Because, in C/C+ + , If in a
comparison one of the values Is of type unsigned,
the other value will be silently 'promoted' to
unsigned too, But a 16-bit integer—as In Ardu-
ino— holding a value of -1 (i.e, Oxffff in two's
complement notation, the way negative values
are represented by most processors) is bitwise
identical to an unsigned integer holding 65,535

54

Movember 2013

www.elektor-magazi ne.tom

(Oxffff), Since 65,535 is larger than 1, the condh
tion will always evaluate to false, and the addition
is never executed— it is unreachable. Requiring
that the programmer removes unreachable code
will either force him/her to rethink the algorithm
or to simplify the program. Remember, less code
means fewer bugs.

This example can be made compliant to the cod-
ing standard either by removing the if-statement,
or by applying the strong data typing rule to
variable b, i.e, adding a typecast to temporarily
make it a signed integer:

if (a< (int) b) a += 2;

Place limits on complexity

Long functions tend to be complex, and that
makes them difficult to comprehend and test.
For this reason a coding standard may forbid
that a function or method contain more than,
say, 200 lines of code.

Coding standard verification tools can use other
metrics to measure complexity. An example is
cyclomatic or conditional complexity that mea-
sures the number of independent paths through
a function. The more paths there are, the higher
the function's complexity. This kind of complexity
is difficult to estimate for a human being— let a
tool do it for you.

Style

Although I said earlier that the purpose of a cod-
ing standard is not to make your code look pretty,
code may include styling rules to make source
code easier to read, Easy-to-read source code
makes identifying potential defects easier too.
Examples of such rules are:

• Source lines will be kept to a length of 120
characters or less;

• Each expression-statement will be on a sep-
arate line;

• Tabs should be avoided;

• All indentations will be at least two spaces
and appear consistent within the same
source file;

• The statements forming the body of an if,
else if, else, while, do-while or for state-
ment shall always be enclosed in braces,
even if the braces form an empty block;

• Braces ("{}") which enclose a block will be
placed in the same column, on separate lines
directly before and after the block.

Many programmers offend against these rules;
some programming editors do too by auto-
matically inserting tabs. BTW, why avoid tabs?
Because they mess up source code formatting
when two or more persons do not use the same
tab distance.

Habits

C/C++ compilers come with a large collection
of so-called standard libraries. Many program-
mers rely on the availability of these libraries,
and use them out of habit. Unfortunately, several
functions included in these libraries may exhibit

Mot counting in-house standards, today the most widespread coding
standards are (in order of popularity):

MISRA C (and C+ + ) — created by the Motor Industry Software
Reliability Association to provide assistance to the automotive industry
in the application and creation within vehicle systems of safe and
reliable software, A small fee must be paid to obtain the standard,
www.misra.org.uk/

CERT C++ (and C) — this initiative from the Software Engineering
Institute of the Carnegie Mellon University strives to eliminate insecure
coding practices possibly leading to vulnerabilities that may be
exploited by malicious entities,

www.cert.org/ (note the use of the http secure protocol https. CERT is
secure all the way.)

HICPP — High Integrity C++, made freely available by PRQA, provides
guiding principles for maintenance, portability, readability and safety by
placing restrictions on the ISO C++ language standard in order to limit
the flexibility it allows.

www,codingstandard,com

JSF AV++ — the Joint Strike Fighter Air Vehicle C++ Coding Standard
by Lockheed Martin, available for free, is intended to help programmers
develop code that does not contain defects that could lead to
catastrophic failures resulting in significant harm to individuals and/or
equipment. (Mot to be confused with the significant harm to individuals
and/or equipment caused by military software that is working perfectly
fine.)

www. jsf . mi I/d o wnioads/docum ents/J SF_AV_C + +_Codi ng_Sta nd ards_
Rev_Cdoc

A long list of static analysis tools for many programming languages can
be found here:

http : //e n .Wikipedia . o rg/ wi ki/ List_of_tools_for_static_code_a n al y sis

www.elektor-magazine.com November 2013

55

Labs

Patriot Missile Bug (1991)

During the first Gulf War, a US
Patriot missile system in Saudi
Arabia failed to intercept an
incoming Iraqi SCUD missile,
leaving 28 soldiers dead and
injuring around 100 other people
The cause was a rounding
error in the time calculations
done by the software making it
ignore some of the
incoming targets.

* The functions atof , atci and atol from the
library <stdlib.h> shall not be used;

* The functions abort, exit, getenv and sys-
tem from the library <stdlib.h> shall not be
used;

* The time handling functions of library ctime.
h> shall not be used.

Note the interdiction of the input/output library
<stdio.h>. Yes, you are supposed to roll your
own print f function.

In the end it is up to you

The example rules listed above— all taken from
real coding standards— may seem severe, but
they are not written In stone, For many rules
coding standards allow exceptions. Other rules
are debatable, and it is up to you to decide if

software bugs kill people

platform -specific, unspecified, undefined, imple-
mentation-defined, or otherwise poorly defined
behavior. Here are a few rules that prohibit the
use of some popular functions and libraries:

• The error indicator err no shall not be used;

■ The library <locale.h> and the setlocale
function shall not be used;

■ The signal handling facilities of < signal . h >
shall not be used;

• The input/output library <stdio.h> shall not
be used;

you want to respect them or not. On the Inter-
net you can find rather philosophical discussions
about certain rules showing that some are even
open for interpretation. Even a coding standard
is subject to bugs,

(130271-1)

[1] GIMU Coding Standard: http://www.gnu.org/
p rep/sta nd ards/stan da rds.html

[2] Top 25 of most dangerous software errors:
http : //ewe, m itre .org/top2 5/

Deadly Radiation Therapy
(1985-1987, 2000)

Due to buggy software the
Therac-25 medical radiation
therapy device could miscalculate
the radiation doses it should
administer. Some patients
received up to 100 times the
intended dose, which killed at
least three of them. A similar bug surfaced
in Panama City in 2000, where therapy
planning software delivered different doses
depending on the order in which data was
entered. This bug killed at least five patients.

Mr*

Li L m

flhfti * * then CL

***** bfideHU's.

**- ® mo ACM r

56 November 2013 www.elektor-magazi ne.com

NOVEMBER 20-21, 2013 I SANTA CLARA, CA

Software

TELCO Congress

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# software tel co
a so ftw a rete I co

Labs

By Thijs Beckers The Elektor FPGA Development Board published

(Elektor Editorial) in the December 2012 issue [1] uses a micro SD

card to store the configuration data needed by
the FPGA at startup- The card can also be used
to store data^ either by the FPGA, the microcon-
troller/ or a PC when connected via USB.

When working on an application for the board,
designer Raymond Vermeulen suddenly ran into
troubles using the SD card. After programming
the FPGA with freshly written firmware, the whole

FPGA board wasn't detected by Windows any-
more. Several attempts were made to fix this,
like unplugging and reconnecting the USB cable,
checking for program errors, et cetera, but to no
avail. It seemed like the SD card had suddenly
gone faulty. Testing the card in a reader however
proved it to be functioning correctly, so the error
had to be somewhere else. But where?

Every possible design flaw was checked and
double checked, every solder joint tested, but
everything turned out to be flawless. Retracing
his steps, Raymond programmed the FPGA one
last time and then It dawned on him: when pro-
gramming the FPGA the software development
environment requires a fair amount of parame-
ters to be set. In the configuration options (see
screenshot) unused I/O pins may be configured.
In fact, they should. Exactly then Raymond admit-
ted to having neglected just what he had been
telling all users of the Elektor FPGA Development
Board to do: set the unused I/O pins to float.

Since the data pins of the SD card are directly
connected to both the microcontroller and the
FPGA on the Elektor FPGA Development Board,
it is mandatory these pins are left floating by the
FPGA, when not in use. The development suite
defaults unused I/O to pufl down , which in most
cases is fine. But in this application it is not, and
this setting has to be actively changed to floatl

^ P i ot Pi opeE ties - C o nftgli i at io n 0 ptki ns

&**gory

General Options
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Property dspiay £vef: Stands v g Display Switch names Default

After Raymond corrected this setting and repro-
grammed the FPGA, the FPGA Dev Board came
to life again and Raymond's application worked
right off the bat. A clear case of practice what you
preach , Raymond! Relieved he found the culprit
he turned to me as I just entered the Labs and
asked if anyone had an interesting story for this
month's .LABS pages...

(130036)

Internet Link

[ 1 ] www .elektor.com/ 1 20099

OK

Cancel

Apply

nap

“ l 1

58

Movember 2013

www.elektor-magazine.tom

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Labs

By Aurelien Moulin

(Elektor Labs Trainee)

\

\

/

T

o

O

o

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ri

PCB P

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p

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your
pm

The Elektor PCB Prototyper [1] is a professional
PCB routing machine designed for routing
own PCBs with isolation tracks down to 100
width, and drilling holes as smatl as 0,2 mm
(,008") in diameter Here at Elektor
Labs— in the cellar to be accurate— we
use our own PCB Prototyper machine
when a PCB is needed in a hurry for build-
ing a prototype, or when we want to experiment
with PCB shapes. Inspired by our very own TAPIR
[2] we looked into the PCB Prototyper's potential
for producing custom-shape PCBs, After some
fiddling we were able to persuade the machine
to produce the shapes we had in mind. To our
great satisfaction we even mastered fabricating
our own 'multilayer' PCB (see photo).

Eager to share our positive experience with you,
our esteemed reader and member, allow me to
guide you in pictures through the steps we took to

master
our PCB

Prototypes
I used Cadsoft
Eagle to design an
example printed circuit
board, and the associated
software PCB Module to control the
PCB Prototypes If, like me, you are
keen to "learn to fly with the Eagle", get
the book! [3]

(130128)

Internet Links

[ 1 ] www.elektor.com/PCBprototyper

[2] www.elektor.com/tapir

[3] www, elektor.com/eagle

In Eagle, select the wire tool to draw lines or the arc tool to produce round
shapes. Make sure you select layer 20 Dimension and set the width to 0.
Mow sketch up your design.

20 Dimension »

Width: 0

The green area is not part of the PCB, and has to be cut
out. Bright red areas will be cut out from: the inside of
the PCB. Export your design using the CAM Processor
Select GERBER RS274X and select the Dimension

Verify that the lines form dosed
polygons, so that each shape delimits
an inside and an outside area*

layer only* Click on File to save the output (name it
'dimension') and click Process Job. Repeat this for the top
layer (select Top , Pads, and Vias; don't forget to rename
your file before processing the job). To create the drill
file, instead of GERBER^RS274X, select EXCELLON and
repeat the process. This concludes the Eagle part.

60

Movember 2013

www.elektormiagazi ne*tom

Mow select the Inside tool and apply it to the two shapes
to be cut out from the PCB. Note that the 'E' is not
properly filled. This calls for some manual fine-tuning.
Cancel the last trace ( ctrl+z ),

Launch the PCB Module software and open a new project.
Click Import Layer, select your top layer and import it
into the top layer. Import a second layer and select your
dimension file. Import this file into Board Outline/Cut -
oofs. Also import the drill file if you need it.

Now let's define the inlines and outlines (terms used in
PCB Module ). Click the Modify tab and select the Outside
tool.

You can try to correct this in Eagle (using a wireframe for the form of the
character), but this means you have to redo all your CAM processing. Instead
we came up with this quick & dirty fix: Draw a polygon (the tool hides behind
the Create tab) that roughly follows the center of the character lines and set it
to inline using the Inside tool.

Put your pointer over the global shape. The color will change from
yellow to white, indicating which polygon you're going to set as an
outline. Clicking the outline should yield this.

Now we need to add some Break-out tabs. Use the Break-out tabs
tool from the Create tab and click on a straight part of the outline.
The software automatically centers the breakout. The default size is
2 mm (.08") which is fine, but you can adjust this to your liking. A
proper end result should look like shown here. Your design is now
ready for the usual processing stages (contour; tool list; machining).
Happy routing l

www.elektor-magazine.com November 2013

61

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©editor cc

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•Industry

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WeatherPro with Sensor Support from Sensirion

The new version of WeatherPro for Android 3*0 now also supports sensors integrated in the cell phone,
such as the humidity and temperature sensor from Sensirion. The sensor data is displayed In the
daily forecast. This enables users to compare the data from their current location with the forecast
values, making them better prepared for any weather,

David Kaiser, the man in charge of product management for WeatherPro at the MeteoGroup weather
service, is pleased to be working with Sensirion: "Many devices, such as the Samsung Galaxy S4,
have an integrated sensor from Sensirion, We wanted to make the data generated by the sensors
available to our customers in those places where they usually go for their daily weather information.
There's not always an official weather station right where an app user happens to be. The sensor
data thereby provides interesting comparison values."

Andrea Wuest, Market Manager Mobile at Sensirion, believes that measuring the humidity and
temperature of the immediate environment gives rise to many new opportunities, "Everyone now
has their own individual weather station with them, which, thanks to WeatherPro, is also linked to
the latest weather forecasts."

The use of such a sensor is only possible thanks to innovative technology in both the hardware and
software. The hardware is the smallest humidity and temperature sensor currently available. It was
specially designed for mobile end-devices by the Swiss high-tech company Sensirion and optimized
to fulfill the industry's unique requirements. The company not only provides the sensor, but also
the corresponding software. Without it, the heat generated by the smartphone itself would make
any measurement of the ambient temperature impossible, Sensirion is currently the only company
to offer an all-in-one solution for ambient sensing of humidity and temperature for smartphones.

www.weattierpro.eu www.s mart, sensirion, com (130202-1)

MIO Console 5.6

Metric Halo announces the immediate availability of
MIO Console v,5.6, a free software upgrade for all
users of the Mobile I/O family of audio interfaces,
including the award-winning 2882, ULN-2, LIO-8 and
UlN-8. Versions, 6 includes the following new features:
I/O inserts for accessing external hardware from
within the MIO Mixer, ConsoleSync hardware/software
synchronization technology, AAX ConsoleConnect plug-in
for compatibility with Pro Tools 11, saving of system
boot states and support for EuCon 3,0. In addition to
these new features, v. 5. 6 continues to improve stability

and compatibility with current and
future versions of Mac OS X.
ConsoleSync is a unique
enhancement to the Mobile I/O
family that benefits both new and
experienced users, ConsoleSync
allows MIO Console to read the
complete state of any attached
hardware seamlessly, automatically
and without any disruption of
running audio. ConsoleSync auto
loads the mixer configuration,
complex signal processing chains.

Monitor Controller settings, analog I/O configuration
and even window layout from the hardware.

With ConsoleSync, new users will experience a
dramatically reduced learning curve for accessing the
power of MIO Console. Experienced users will value the
ability to have MIO Console re-connect to the hardware
with exact recall of the current hardware state and
no disruption of audio. For live sound and monitoring
applications this allows the user to disconnect and
re-connect the computer or quit and launch MIO
Console without being concerned about introducing
dropouts to ongoing primary and backup recordings or
to the monitoring paths for talent
I/O inserts streamline the use of external analog and
digital processors within the MIO mixer. This new feature
also allows inserting processors that are hosted on the
computer directly within the signal flow of the MIO low-
latency hardware mixer. This enables the use of host-
based reverbs and delays with greatly simplified routing.
This free upgrade continues the Metric Halo tradition
of adding value to the Mobile I/O platform as well as
enhancing the product for new users. A 30 -day money-
back guarantee backs Metric Halo's hardware products
so you can try them out in your studio with no risk.

www.mhlabs.eom (13Q306-VII)

64 | November 2013 | www.elektor-magazi ne.com

news & new products

Library of Apps for
Jupiter Turn-Key DSP

Symetrix announces the addition of
seventeen new apps for its family of Jupiter
app-based turn-key DSPs, The three different
hardware units in the series— Jupiter 4 ,
Jupiter 8, and Jupiter 12— differ only in their
input/output counts and are user-controllable
from Symetrix ARC wall panel remotes,
third-party systems, and Symetrix ARC-WEB
browser-based software for smartphones.
The addition brings the total number of
available Jupiter apps close to one hundred
and expands the already impressive range
of situations for which the Symetrix Jupiter
provides reliable processing at an extremely
competitive price point.

Six core apps form the heart of the addition
and are elaborated according to the input/
output counts of the three Jupiter hardware
devices. "BGM Zone Mixer 1" provides
background music routing to multiple zones
with two levels of priority. "Dual Matrix
Mixer 1" provides flexible mixing and routing
and allows integrators to assign any input to
a mix, assign those mixes to submixes, and
route submixes to outputs. "Gain-Sharing
Automixer 3" provides a gain-sharing
automixer with feedback processing on the
outputs together with matrixed outputs.
Similarly, "Gating Automixer 3" provides a
gating automixer with feedback processing on
the outputs together with matrixed outputs,
"Priority Zone Mixer 2" provides a multi-zone
priority mixer with paging and SPL computing.
Finally, "Sound Reinforcement 12" provides
heavy input processing and full-range outputs
with feedback processing.

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The growing library of Jupiter apps are optimized for
specific applications and venues including houses of
worship, auditoriums, retail and hospitality establishments,
sports facilities, and transportation terminals. The time
needed to learn the software is zip. With Jupiter turn-key
DSP sound contractors end up doing what they do best,
which is to dial in really great sound.

www* symetrix. com (130202-III)

www.elektonmagazine.com | November 2013 | 65

•Industry

Quad-Core CPU in Fanless Chassis

Logic Supply has released
the LGX AU970 Intel® Core™
Fanless Computer. Designed
for demanding industrial
applications like high-end
automation, data collection
and surveillance, this tough,
wide- tempera tore system
takes ruggedized, high-
performance computing to a
whole new level
The AU970 offers high-
performance computing for even the most graphics-
intensive applications. It supports up to 16 GB dual-
channel 1333 DDR3 memory, and comes equipped
with a dual- or quad-core third-generation (Ivy Bridge
mobile) Intel Core i3/i5/i7
CPU and QM77 chipset.

Third-generation Intel Core processors efficiently deliver
top-oHhe-line graphics performance while taking up
very little space. Logic Supply is among the first to offer
this technology in a fanless chassis*

A comprehensive array of I/O allows for a wide range of
connectivity options, including two eSATA and CFast ports
for external storage, a SIM card slot for 3G connectivity
in remote deployments, and an 8-bit Digital I/O port The
AU97Q has 3 LAN ports (one with Intel iAMT for remote
support), 10 USB ports, 4 COM ports and 2 DVI ports
for dual independent display. The system has a secure
terminal block connector for wide input 9-32 V DC power
with remote power-switch capability.

The system's heavy-duty heatsink and chassis provide
fan less cooling, with a wide operating temperature
of -20C to 55 °C The fanless design ensures silent
operation, as well as reliability in highly dust- and dirt-
prone environments. It also comes equipped with a
wall-mounting kit for easy installation.

The AU970 is available exclusively from Logic Supply.
Also available is the LGX AU972 Expandable Computer,
which, in addition to the above, offers dual PCI express
expansion slots for a variety of additional I/O— from
network port additions to COM ports and specialized
hard drive hot-swap bays.

www. log i csti p pi y.com (1 303 0 6- VII I)

New Temperature Range for KPSI 342

Measurement Specialties has improved the operating temperature range for the KPSI Model 342 submersible level transducer. The 342
transducer can now withstand temperatures up to 85°C for use In hostile fluids providing a 4-2GmA analog output with digital transducer

performance.

The Model 342 is a small bore (3/4 rH body diameter) submersible hydrostatic
I level transducer that combines Measurement Specialties' well known sensor
competencies with the latest in Application Specific Integrated Circuit
(ASIC) technology. The addition of the ASIC has given the Model 342 digital
performance in an analog product over the entire operating range.

The Total Error Band specification (±0.25% FS) over the compensated temperature range (-20 to 85°C) eliminates the user having to combine
multiple performance specifications to realize the total accuracy of the transducer. While numerically larger, it is a more accurate specification
because it defines linearity of the sensors' performance as a total rather than using the traditional definition, which takes the difference
between the largest positive and negative linearity values. The Model 342 is available In vented, sealed, and absolute formats to 3GQpsi (700'
H 2 0 WC level) full scale output

www,meas-spec,com (130202-11)

True RMS Self-Powered AC Voltmeter

Fits 30.5 mm / 1.20 Inch Round Panel Cutouts

Mu rate's Type DMR20-1-AG/ "nanometer" self-powered
four-digit bright LED voltmeter can measure the true
RMS value of its input from 85 to 264 VAC to within 0.1
V resolution* Designed to be completely self-contained,
the low cost two-wire voltmeter requires no additional
components or connections apart from the AC voltage it is

measuring. It is capable of accurately measuring quasi -sine
AC source such as modified, modified 2-step and modified
3-step sine wave in addition to conventional sine, triangle
and square wave inputs.

The voltmeter fits an industry standard "oil tight" 30 and
30,5 mm / 1.2 inch round panel cutout. The 7.6 mm

66 | Movember 2013 | www.elektor-magazine.eom

/ 0.3 inch four-digit LED display is housed
in a rugged round polycarbonate case that
provides protection against dust, moisture,
vibration and shock. It is supplied with an
EPDM rubber gasket and plastic hex nut that
aid protection to IP67 / NEMA6 specification
for water ingress.

The DMR2G-1-ACV is ideal for measuring the
AC line voltage of a wide range of applications
such as primary line power, power distribution
units and backup power generation sources.
The voltmeter consumes a maximum of 30
mA when used at 250 VAC / 60 Hz.

Round knockout punch tooling can be
ordered with the DMR2Q, Free sample /

evaluation units for qualified OEMs are
available from stock.

www.murata-ps.com (13Q2Q2-1V)

PC Oscilloscopes with Deep Buffer Memory
and USB 3.0 Superspeed Interface

With up to 500 MHz bandwidth on four channels, and an industry-leading 2 G samples
of buffer memory, the new PicoScope 6000 Series has both the performance and the
advanced analysis capability to speed debug of today's complex electronic designs.

The PicoScope 6000 Series employs hardware acceleration and a USB 3.0 interface to
acquire and display many megasamples of data per screen update without slowing down.
Engineers can observe large portions of their design's electrical behavior at one time,
and in great detail, which helps to reduce debug cycles and enables electronic design
projects to be completed on schedule.

As Alan Tong, Managing Director of Pico Technology, explained, "The PicoScope 6000
Series is the highest-performance USB oscilloscope, with deeper buffer memory as
standard than any other oscilloscope, and is capable of detailed circuit analysis. We have
provided a suite of advanced debugging tools, included as standard with the scopes, so
that engineers who are developing complex electronic systems will find all the functions
they need."

All models include an integrated function generator or arbitrary waveform generator
(AWG), advanced triggering, automatic measurements with statistics, an EFT spectrum
analysis mode, comprehensive waveform maths, mask limit testing, and serial decoding
for popular industry standards such as PC, 5PI, UART, CAN, LIN and FlexRay.

The PicoScope 6000 Series scopes are compact and portable devices that fit easily in
a briefcase, and include a five-
year warranty as standard.

Prices start at €2414 / $3292
/ £1995 for the 250 MHz
model with function generator,
through to €5439 / $7417 /

£4495 for the 500 MHz model
with arbitrary waveform
generator and 2 G samples of
buffer memory. A set of four
high-quality matched probes is
supplied with every scope.
www.picotech.com (130202-V)

flj

prices

6-IN-1 SCOPE

* 2-ch 2MSa/s 200KHz il-oit scope

- 2-ch spectrum analyzer
-2MSa/s 8-bit AWG

- Function generator

- Networ k a na ly ze r V

- PWM/Digitai I/O

CSM-IOI $99.95
30MHz SCOPE

2-cn 250MS/S I
sample rate
30MHz scope
with 8" color
TFT- LCD, AUtOScaie ^

ar>a waveform matnmatic functions,
FREE carry case Included!

SDS5032E $299
60MHz SCOPE

SOM HZ 2-cn scope
with SdOMSa/s rate
& huge lOMSa memory !

8* color TFT-LCD & FREE carry case!

SDS60G2 $3H9
100MHz SCOPE

High-end lODMHz 2-ch %

IGSa/s Denchscope
with IMSa memory
ana USB port ■ FREE
scope carry case. Super low price!

DS1102E $399

100MHz SCOPE

100 MHZ 2-ch scope
with 165/ s sample
rate ana 8* color TFT
Leo. Huge amounts
of memory * FREE scope carry case.

SDS7102 $H29

o fj

caA

100MHz MSO

2-cn loowsa's
scope * 8-ch ioglc
analyzer, USB 2.0 and
4M sampes storage per channel with
advanced triggering & math functions.

CS328A $1359
20MHz HANDHELD

Fast & accurate handheld
20MHz 1-ch oscilloscope.

- 100 M/S sample rate

- 3.5 in. color TFT-LCD

- 6 nour battery life
FREE rugged, impact -resistant caset

HDS1021M $269.93

9 "a it,

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www.elektor-magazine.com | November 2013 | 67

Tech The Future

Forze VI:

A Hydrogen-Powered Racecar

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BAUARD

Chroma *

ByTessel Renzenbrink

(Elektor TTF Editor)

The Forze VI, one of the
first hydrogen-powered
racecars, was unveiled on
September 9 at the disused
Valkenburg airfield near
Katwijk (Netherlands).

All components of the car
were built by a team of 70
students at the Delft Uni-
versity of Technology,

The Forze VI and The Team

The symbolic value of the location was a good
match for the objective of the Forze team, In
scarcely less than a century, aviation technol-
ogy has radically changed our world and now
allows us to travel to the other side of the globe
in less than 24 hours. With their hydrogen-pow-
ered racecar, the students hope to contribute to
another technology-driven revolution, this time
in the realm of clean energy.

The Forze VI weighs just under 2,000 lbs.
(880 kilograms), achieves a top speed of 138
mph (220 km/h), and accelerates from 0 to 60
mph (100 km/h) in 4 seconds. The heart of the
racecar Is the fuel cell system, where hydro-
gen reacts with oxygen to produce electricity
and water. The generated electrical power drives
two electric motors, each with a rated power of
190 kW (260 HP), The car can race for 30 min-
utes at top speed on the fuel in its two tanks,
which together hold three kilograms of hydrogen
at a pressure of 350 bar.

Sustainability can be coo!

In Hanger 2, Edgar van Os— the founder of the
Forze team— explained to the audience what moti-

vates the students to devote so much time (some-
times up to 80 hours per week) to the project*
“We want to show that sustainable energy can
also be cool Sustainability is always presented
in a negative sense: switch off the light, turn
down the heating, and so on. Our approach of
combining sustainability with racing was radical
and pioneering. That is why we also gave a lot of
attention to the appearance of the car. It is not
a nerdy engineering-student vehicle, since that
doesn't interest the general public."

Van Os set up the Forze H2 team in 2007 entirely
on his own initiative, without any help from spon-
sors or professors. The goal was to build a go-cart
that could participate in the Formula Zero com-
petition in 2008* This first series of races for
vehicles powered by hydrogen fuel cells was ini-
tiated to foster zero-emission technology "from
the source to the wheel". The Forze I vehicle
competed against entries from five other uni-
versity teams and came out on top.

Since then the Forze platform has undergone a
number of evolutionary developments, with each

6 8 Mo vem ber 2013 www. el e kto r- m a ga z i n e . to m

Hydrogen-Powered Racing

team building on the knowledge of its
predecessors. Development of a hydro-
gen fuel celf designed and built by the
team, to replace the ready-made fuel cells
used previously, started in 2010. This was
installed for the first time in the Forze IV,
which also marked the change from a
go-kart platform to a small racecsr. Now
the team has delivered the first full-size
race car in the form of the Forze VI.

Hydrogen

After the introductory remarks by Van Os,
Dr. Bernard Dam, a professor of chem-
istry at Technical University Delft, gave
a short talk on the benefits of hydrogen
fuel systems. "Global warming is a sci-
entific fact. It is therefore necessary to
reduce C0 2 emissions by 80 to 90 percent
by 2050, relative to the level in 1990.
Mobility plays a major role in this. Reduc-
mg emissions in the industrial sector is
difficult, which is why the answer must
be found in the transport sector and the
urban environment— office buildings,
houses, shops and so on,"

Right now there is a lot of interest in the
development of electric vehicles equipped
with batteries. If the electricity is gen-
erated from renewable energy sources,
this results in zero-emission vehicles. A
side benefit is that this pool of vehicles
can act as a distributed storage system.
Wind energy and solar energy deliver
a fluctuating yield of electricity, which
makes it necessary to create facilities for
storing energy.

However, according to the professor "it
is by no means certain that affordable
batteries that allow vehicles to travel a
thousand kilometers will become available
in the future/' The popularity of electric
cars still suffers from "range anxiety":
the fear of getting stuck alongside the
road somewhere with an empty battery,
A hybrid hydrogen-powered car can pro-
vide a remedy by using the fuel cell as a
range extender.

Dr. Dam and his colleagues are working
on a method to produce tow -cost, sus-
tainable hydrogen in the future. Pres-

ently most hydrogen is obtained from
natural gas. This process still generates
C0 2 emissions, and natural gas is not a
renewable resource. The method being
investigated by Dr. Dam is called water
splitting. This involves first immersing a
photo-electrochemical cell in water and
then exposing it to sunlight. The resulting
chemical reaction splits the water into its
constituent elements: hydrogen and oxy-
gen. The researchers recently achieved
a milestone by attaining an efficiency of
4.9%. This means that nearly 5% of the
solar energy is converted into hydrogen.
They expect to be able to achieve their
efficiency target of 10% within three
years, which would make the technol-
ogy commercially viable.

Water

When hydrogen reacts with oxygen in
the fuel cell, the only by-product is pure
water. The Forze VI produces a liter of
water every minute. The water can be
stored in the car or discharged onto the
road surface. Neither solution is ideal:
the first option makes the car heavier,
while the second option leads to jeers
from other motorists. For this reason,
the Delft team came up with an inno-
vative alternative. They use the water
to cool the brake system, which causes
the water to evaporate. The kinetic
energy from braking is also converted
into electrical energy and fed back into
the system.

The Forze VI from the student team is
a full-fledged racecar that will compete
with cars powered by gasoline. It will be
entered in 25 events during the 2013-
2014 race season. One of the highlights
is an attempt to break the lap speed
record for electric vehicles at the Zand-
voort track. The record is currently held
by the Tesla Roadster, At the famous Ger-
man Niirburgnng race circuit, the Forze
team hopes to enter the record books as
the builders of the fastest hydrogen fuel
cell powered car that ever rode on the
Nordschleife (North Loop).

( 130203 - 1 )

www.elektor-magazine.comj November 2013 69

•Magazine

By Dr. Gotz Corinth

(Germany)

Figure 1*

Block diagram (partial)
of the Audio-Frequency
Spectrometer Note the
photo camera, 'P'. US Patent
Office file# 2,159,790, May
1939; Z Tech. Phys. 16
(1935), p, 294 (Freystedt)

Freystedt's Audio-Frequency
Spectrometer (1935)

Restoration of a landmark in
electro-acoustic measurement technology

As opposed to time consuming mechanical, optical and graphic/mathematical
methods, electronic engineering in the mid-1930s brought new possibilities
to sound analysis. Filter circuits allow individual frequencies and frequency
bands to be stressed or suppressed. The 'search frequency' method allows
highest resolution to be achieved at constant absolute bandwidth, but at the
expense of analysis speed.

A pass-band filter fitted ahead of a multichannel
looping oscillograph (in German: Schleifenoszil-
lograph) enabled parallel recording of multiple
frequency ranges. Attempts at real-time visual
assessment remained problematic though.

In 1934, Erich Freystedt at Siemens & Halske's
Centra] Laboratory improved the process by
means of 27 parallel third-octave filters at the
input, covering the 30-18,000 Hz human hear-
ing range ("analysis with constant relative band-

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Retronics is a monthly section covering
vintage electronics including legendary
Elektor designs. Contributions, suggestions
and requests are welcome; please telegraph
editg r@e.l e.kto.r

width"). Looking at Figure 1, after rectification
and short-term storage in capacitors, the niter
output signals are continuously sampled by a
motor-driven switch assembly, and subsequently
applied to the vertical deflection plates of a cath-
ode ray tube (CRT), on which the signal levels
appear as columns.

Synchronously, an appropriate DC voltage level
Is applied to the horizontal deflection piates. The
resulting image on the oscillograph represents a
line spectrum. Each line represents the peak volt-
age obtained from "third -octave" filtering, care-
fully taking into account the electrical properties
of capacitors and filters (Figure 2). Depending on
the sampling rate a sort-of continuously updated
image of the spectrum is generated, of which
the time domain can be registered additionally.

Where is the Spectrometer?

There was the vague, but not entirely unfounded
hope that such an instrument might just be part
of a private collection in Russelsheim, Germany.
Russelsheim? Errm... Opel? (later, General Motors
Europe, Ed.) What! Noise tests on car engines?
Indeed, the suspicion was confirmed: this spec-
trometer was built in 1937 and appeared to be at

least fairly well preserved, at least on the outside.
All 200 lbs. (85 kg) worth of AF Spectrometer
was hauled into the author's electronics labora-
tory with difficulty.

Where is the documentation?

In terms of documentation, initially there were
only two original publications from Siemens and
ATM Scientific Publications. Later, a Dutch col-
lector was contacted through PTB's (Physika-
lisch-Technische Bundesanstalt) Technical Acous-
tical Division. He was willing & able to supply the
original documentation from Siemens. The papers
also contained an equipment price indication from
1938: RM (Reichsmark) 5,500. According to Ger-
many's Federal Statistical Office that's $35,000
or €25,000 referenced to the year 2000,

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Figure 2.

Detailed schematic of the
Spectroscope instrument
(from factory documentation
Ref beschr. 745 g. (Siemens
& Haiske company, 1936).
Schwere Worter translated:
Eingang = Input;

Verstarker = Amplifier;
Ubersteu rungsschutz -
Overdrive Protection;
BandpaS = Bandpass;
Gleichrichter - Rectifier;
Braunsche Rdhre - Cathode
Ray Tube; Netzteil - Power
Supply; Schaltung - Circuit.

www.elektor-magazine.com I November 2013 | 71

•Magazine

Figure 3.

Drive motor and camshaft
switching gear comprising
54 spring sets, (original
photo)

Figure 4,

Frequency response of the
filter before the equipment
restoration, (original
recording)

Electrical checking, investigating,
restoring

First cautious attempts: the drive motor for the
two sets of 27 cam switches (Figure 3) was
stuck; no high tension (HT) for the 7-inch (18
cm) cathode ray tube ("Braun'sche Rohre") with
asymmetrical deflection. Unfortunately, this tube
had become unusable due to corrosion of the
wires at the pinched base. Only the audio fre-
quency (AF) part of the instrument seemed to
be functional to some extent.

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The high tension transformer had to be rewound
twice until it kept working in the circuit. A spe-
cialist firm in Holland overhauled the cathode
ray tube, giving it a completely new electron gun
and screen. The AF section of the instrument was
thoroughly checked, and unsafe components got
replaced.

The readjustment of many filters was necessary
as well as labor intensive (Figure 4), Here the
capacitors showed up increased capacitance—
probably due to shrinkage of insulating paper
over a period of nearly 70 years— ruling out the
simple knack of connecting a few small extra
capacitances in parallel. Two capacitor decade
banks and a computer-controlled sweep genera-
tor ("wobbulator") allowed the target pass-band
curves to be set up again (Figure 5), The "Siru-
tor" cuprite (Cu 2 0; a minor ore of copper) rectifi-
ers between the filter and the storage capacitors
all proved completely intact.

To be able to operate the "new CRT in a vintage
envelope" the setting options for the tube's aux-

Figure 5.

Frequency response of the
filter after recalibration,
(original recording)

72 | November 2013 ] www.elektor-magazi ne.com

.<p.et*atuc& XXL

iliary voltages had to be reconsidered, resulting
in practice in a small circuit board being etched
and corresponding potentiometers installed on
it, for retro-fitting inside the instrument. To
avoid making excessive alterations to a his-
torical piece of equipment, the strictly correct
method was relinquished of applying symmet-
rical voltages to the CRT by a push-pull driver
circuit. CRT trapezoidal skew and astigmatism
proved tolerable at not too high deflections
(Figure 6),

Mechanical work

The motor fitted with new bearing bushes (home
made on a precision lathe), and all 54 spring
assemblies adjusted using a stroboscope, a spec-
trum appeared for the first time on an external
oscilloscope.

Figure 6.

Screen snapshot of a
distorted sinewave voltage,
(original recording)

After the restoration of the electrical parts, the nickel-plating metal components and making new
exterior was rebuilt by repainting the cabinet, lettering on and around the controls {Figure 7),

\r r-r: cp

nenc

powered by Eurocircuits

Elektor

Benefit now: Elektor PCB Service offers a permanent
90-day launch discount on new Elektor PCBs!

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www.elektor-magazine.com [ November 2013 | 73

•Magazine

Figure 7. View of the audio-frequency spectrometer
near completion of the restoration work. The casing
is removed to show the 27-section filter bank and the
motor-driven contact array. The modern multi-color
parts were required to electronically match the reworked
CRT to the original circuit, (original photo)

Back Home

The result of a tl the restoration work covering
many weekends finally ensured that a monu-
mental piece of electro-acoustic measurement
technology was operational again. The finished
instrument was discussed by the author in a pre-
sentation to the 2007 German Society for Acous-
tics Congress, and afterwards consigned as a
free, permanent loan into the historical collection
of the original manufacturer, Siemens, Munich,

Eiektorized in 1984

The March, April and May 1984 editions of Elek-
tor magazine (priced 95p/$3) contained a 3-part
article series describing a "real-time analyzer"
(sic), which may be considered the All-Solid-
State & Performance-Plus version of the 1935
Siemens boatanchor described here, although
that instrument failed to get a mention in 1984.
In good 1980s fashion the Elektor DIY project
contains vast quantities of discrete parts (how
about 250-odd precision resistors), half a dozen
of densely stuffed circuit boards mounted on a
base board, a hefty power supply and a colorful
readout comprising 330 LEDs. A pink noise gen-
erator is also included.

The lab prototype of the 1984 real-time analyser
probably ended up in a dumpster In preparation of
Elektor's office move from Beek to Elektor House,
Limbricht, back in 2008, All we have today are
the original articles. Mot to worry— thirty years
on we cheerfully run or the likes of it on a laptop
PC, It's just a 500 KB download away. Some of
you have ARM cores, DSPs and hidden speaker
systems turning a bubble car or an Opel Kadett
A into a Ferrari as far as sound is concerned.

Figure 8. Finished prototype of the Elektor real-time
analyser, photographed from an Elektor May 1984 page,
(original reproduction by copyright holder)

Your Editor cant resist signing off with Figure 8—
it's his best attempt at showing what the Elektor
1984 instrument looked like* It was designed by
Harry Baggen who is still on the Elektor Nether-
lands editorial staff. Owners of an Elektor 1984
real-time analyser, please telegraph editor@elek-
tor,com.

(130204)

74 1 November 2013 j www.elektor-magazi ne.com

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•Magazine

Hexadoku Puzzle with an electronic touch

Here you stumble upon a new specimen of our popular Hexadoku, the 16-by-16 puzzle that's sure to keep you busy for
a couple of hours. Hexadoku is not just for electronic engineers, but also for their relatives and friends! Find the solution

in the gray boxes, submit it to us online, and you automatically enter the prize draw for one of four vouchers.

The Hexadoku puzzle employs numbers in the hexadecimal
range 0 through F. In the diagram: composed of 16 * 16 boxes,
enter numbers such that all hexadecimal numbers 0 through F
{that's 0-9 and A-F) occur once only in each row, once in each
column and in each of the 4*4 boxes (marked by the thicker

black lines). A number of clues are given in the puzzle and
these determine the start situation.

Correct entries received enter a prize draw. All you need to do
is send us the numbers in the gray boxes.

Solve Hexadoku and win!

Correct solutions received from the entire Elektor readership
automatically enter a prize draw for one Eurocircuits PCB voucher
worth $ 140.00 (£ 80 . 00 ) and three Elektor book vouchers worth
$ 60.00 (£ 40 . 00 ) each, which should encourage all Elektor readers to
participate.

Participate!

Before December 1, 2013,

supply your personal details and the solution (the numbers in the
gray boxes) to the web form at

www.elektor.com/hexadoku

Prize winners

The solution of the September 2013 Hexadoku is: 569E8. The Eurocircuits $140.00 (£80.00) voucher has been awarded to Emil Cugtni (Switzerland).
The Elektor $6G.QG(£40,00) book vouchers have been awarded to Arno Habermann (Netherlands), Richard Fletschmann (USA), and Arun Annaji (India).

Congratulations everyone!

B

0

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A

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The competition is not open to employees of Elektor International Media, its business partners and/or associated publishing houses.

76 I November 2013 | www.elektor-magazme.com

Gerard's Columns

Conscientious Objector

By Gerard Fonte (USA)

]

Edward Snowden has received a lot of publicity
about revealing the CIA's analysis of
telephone and Internet activity in
the US. So, it seems appropri-
ate to discuss what to do when
you are in such a situation. It is
unfortunate but true that being asked
to do something that you find unethical
is not uncommon in the engineer-
ing arena (especially for government
and/or product design). And while your
circumstances may not be as conspicuous, they are certainly
nt to you. Here's my story.

Background

In the early 1 980's I was working for an aerospace
design and development firm that specialized in gov-
ernment contracts. I was chosen as lead engineer for a
Flight Inspection project. Flight Inspection is the calibration of civilian
airport equipment that identifies the position of aircraft as they near the
airport. Obviously, it's very important that when the airport instruments
say that the aircraft Is ten feet to the right of the runway centerline, the
aircraft is really and truly ten feet right of the centerline. This was a
plum and very visible assignment and it was very important to me for
my advancement at the company.

Unfortunately, some ignorant VP had already sold a "design" to the client.
The idea was to put a digital TV camera in an aircraft; fly the aircraft
fifty feet over the runway; take a picture of the runway number; analyze
the picture to determine the aircraft's precise position over the runway;
and then compare the "known" position with the airport's instruments
for error. The best digital camera of the time had a resolution of about
1000 by 1000 pixels. There were eight-bit, single-board computers oper-
ating at a few MHz available. There were no real operating systems or
math packages or optical recognition software. It all had to be written
fro m scratch,! n- ho us e.

I had recently taken some graduate courses in pattern recognition and
artificial intelligence and knew immediately that this was not an easy
thing to do. I asked how precise the positioning of the test aircraft had
to be. I was told: "To the inch", 1 swallowed hard and said nothing, I
took the specifications to my desk and gat busy.

You Can't Get There From Here

It was Immediately apparent that there were major troubles. The
runway markings were spray-painted by hand, I suspected that they
could be off by at least an inch or two whenever the runway was

re-painted— which was often. That was over the error budget by
itself. (It was later determined that this error could be as much as
five inches.) However, I ignored that for the time being and worked
out a hardware error figure.

With 1024 pixels and a runway 150 feet wide, each pixel was 1.75 inches.
The basic resolution of the camera was simply not good enough by nearly
a factor of two. I then added in the speed of the plane, shutter speed
of the camera (30 fps), altitude error (from a laser altimeter) and other
error sources. The expected error was about 12 to 14 inches or over an
order of magnitude worse than what was required. This did not include
software error or runway marking error. I had a problem,

I talked to my immediate boss about this and he passed it upwards.
After a week with no response, I put my error analysis on paper and
passed that up the chain. After another week, I re-worked the analysis
with more details and sent that paper through channels. The next week
a different engineer was given the task to determine what the error
was. His expected measurement error was two to three feet. However
about half of that could be calibrated out, leaving an uncorrected error
of about 12 to 18 inches,

I thought on the problem and realized that they might not know any
other method. So I came up with my own approach. It used several
semiconductor lasers set at special angles on the plane with four bicycle
reflectors glued to the runway lights. It was very cheap, very precise
(0.1" resolution) and very simple. I built a demonstration model using
my personal He-Ne laser and some lenses. I showed it to my boss, who
liked the idea. However, a few days later I got the word that the idea was
rejected because "we can't put anything on the runway." Not because of
any legal or safety concern, but because the original VP's "design" said so.

Final Answer

Several days after this I was in an Informal meeting with my boss and
a director. When the topic came up I asked: "How are going to address
the error problem?' To this point I had gotten no feedback at all. The
director, obviously annoyed and frustrated with my persistence, blurted
out: "Well cheat. Everyone does," I resigned a few weeks later. The
project went forward with a special optical design placed on the ground,
to one side of the runway, I don't know if the error problem was ever
fixed. A couple of years later some of these same people were indicted
on contract procurement irregularities.

Different people would make different choices. There is no "right' answer
to this problem. Each individual has to evaluate the situation and choose
the course that is best for him or her. However, I still think that I
addressed the matter in a reasonable and proper manner. And that is
the moral of this story.

(130372)

www.elektornnagazine.ccmi | October 2013 | 77

•Store

Mastering

Microcontrollers

Limited Time Offer for GREEN and GOLD Members!

I50/0 DISCOUNT

www.elektor.com/arduinobook

Helped By Arduino

I Mastering Microcontrollers

The aim of this book is not only to let you enter the
World of Ardusno, but also to help you emerge victori-
ous and continue your microcontroller programming
learning experience by yourself In this book theory
is pul into practice on an Arduino board using the
Arduino programming environment.

Having completed this fun and playful course, you will
be able to program any microcontroller, tackling and
masteri n g I/O , m em or y , inte rru pts, communication
(serial, PC, 5PI, 1-wire, SMBus), A/D converter, and
more. This book will be your first book about micro-
controllers with a happy ending!

348 pages * ISBN 978-1-907920-23-3
£34.95 * C 39.95 * US $56.40

Learning to fly with Eagle

f EAGLE V6 Getting
Started Guide

This book is intended for anyone who wants an
introduction to the capabilities of the CadSoft's EAGLE
PCB design software package. This book will quickly
allow you to obtain an overview of the main modules
of EAGLE; the schematic editor; layout editor and
autorouter in one single interface. You will apply your

knowledge of EAGLE commands to a small project,
learn more about some of the advanced concepts
of EAGLE and its capabilities and understand how
EAGLE relates to the stages of PC8 manufacture.
After reading this book while practicing some of the
examples, and completing the projects, you should
feel confident about taking on more challenging
endeavors,

208 pages * ISBN 978-1-907920-20-2
£29.50 * € 34,50 * US $47,60

The luxury of precision within everyone's reach

B 500 ppm LCR Meter

The remarkable precision of this device and its amazing
ease of use are the result of careful design. It works
so well behind its uncluttered front panel that one
could almost forget the subtleties of the measurement
techniques employed, A dream opportunity for our
readers who are passionate about measurement to
enjoy them selves. If, like us, you wonder at the marvels
modem techniques bring within our reach, come along
and fed the tiny fraction of a volt.

Set: main board and LCD board,
assembled and tested
Art.# 110758-93
See www.elektor.com/lcrmeter

Display, buttons, real time clock and more

Elektor Linux Board
* Extension

This extension board was developed to further
propel our Embedded Linux series of articles and the
matching GNUblin board, !t has a display, buttons,
a real time dock arid 16 GPIOs. Linux devotees,
switch on your solder irons. The Linux extension
board includes everything needed to provide the user
interface for a wide variety of projects!

Module, SMD-populated and tested board, Incl.
LCD1, XI, K1-K4, BZ1, BT1 for home assembly
Art.# 120596-91
£31.10 • t 34.95 • US $50.20

140 Minutes video presentation and more

I* DVD Feedback in
Audio Amplifiers

In this Masterclass we address several aspects
of feedback in audio amplifiers. The focus of this
Masterclass, although not entirely math-free, Is on
providing insight and understanding of the issues
involved.

Presenter Jan Bidden provides a clear overview of
the benefits that can be obtained by feedback and its
Sibling, error correction; but also of its limitations and

78 | November 2D13 | www.elektor-magazme.com

Books, CD-ROMs, DVDs, Kits & Modules

E

Android Apps

prog ramming st^p-by.^p

ww*.dp4*ar > afiv'L mki r-C-

disadvantages. Recommended to audio designers and
serious audio hobbyists!

ISBN 978-907920-16-5
£24*90 • C 29.95 • US $40*20

Taming the Beast

[ FPGA Development Board

FPGAsare unquestionably among the most versatile but
complex components in modern-day electronics. An
FPGA contains a maze of gates and other circuit elements
that can be used to put together your own digital circuit
on a chip. This FPGA development board (designed in
the Efektor Labs) shows how easy it is for any electronics
enthusiast., whether professional or amateur, to work
with these programmable logic devices.

Module, ready build and tested Art*# 120099-91
See www. elektor.com/fpgaboard

Programming step-by-step

\ Android Apps

This book is an introduction to programming apps
for Android devices. The operation of the Android
system is explained in a step by step way, aiming to
show how personal applications can be programmed.
A wide variety of applications is presented based

on a solid number of hands-on examples, covering
anything from simple math programs, reading
sensors and GPS data, right up to programming
for advanced Internet applications. Besides writing
applications in the Java programming language, this
book also explains how apps can be programmed
using Javascript or PHP scripts. When it comes to
personalizing your smartphone you should not feel
limited to off the shelf applications because creating
your own apps and programming Android devices is
easier than you think!

244 pages • ISBN 978-1-907920-15-8
£34*95 ■ € 39*95 • US $56*40

More than 75,000 components

. CD Elektor's Components
Database 7

This CD-ROM gives you easy access to design data
for over 11,100 Its, 37,000 transistors, FETs,
thyristors and triacs, 25,100 diodes and 2,000
optocouplers. The program package consists of
eight databanks covering ICs, transistors, diodes
and optocouplers. A further eleven applications
cover the calculation of, for example, zener diode
series resistors, voltage regulators, voltage dividers
and AM Vs. A colour band decoder is included for

determining resistor and inductor values. All
databank applications are fully interactive, allowing
the user to add, edit and complete component data.

ISBN 978-90-5381-298-3
£24*90 • C 29*50 * US $40*20

80 tales of electronics bygones

E Retronics

Quite unintentionally a one-page story on an old
Heathkit tube tester in the December 2004 edition of
Elcktor magazine spawned dozens of 'Retronics' tales
appearing with a monthly cadence, and attracting
a steady flow of reader feedback and contributions
to the series. This book is a compilation of about 80
Retronics installments published between 2004 and
2012. The stories cover vintage test equipment,
prehistoric computers, long forgotten components,
and Elektor blockbuster projects, all aiming to make
engineers smile, sit up, object, drool, or experience
a whiff of nostalgia. Owners of this book are advised
to not exceed one Retronics tale per working day,
preferably consumed in the evening hours under lamp
light, in a comfortable chair, with a piece of vintage
electronic equipment close and powered up.

193 pages • ISSN 978-1-907920-18-9
£24,80 * € 29,95 * US $40,00

www.elektor-magazine.com | November 2013 | 79

•Store

Wireless and button-free

_ Android

Eiektorcardioscope

Instructive, fascinating, and potentially useful to
everyone: perform your own electrocardiograms
on your Android smartphone or tablet! The project
involves skillfully combining a small PIC interface to
control an analog input stage with a great deaf of
software., Our ECG interface is available in the form
of a ready- to-use module to which you just have to
add four electrodes and an Android application for
smartphone or tablet; there's no physical connection
between this terminal and the interface, as it uses
Bluetooth communication!

Ready assembled board * Art.# 120107-91
Se e www, elektor. com /ele kto rcard i oscope

10 captivating lessons

. PIC Microcontroller
Programming

Using the lessons in this book you learn how to
program a microcontroller. You'll be using JAL, a free
but extremely powerful programming language for
PIC mi c ro co ntr o II ers. Ass u m i n g you h a ve a bsorbed
all lessons you should be confident to write PIC
microcontroller programs, as well as read and

understand programs written by other people. You
learn the function of JAL commands such as include,
pin, delay, forever loop, while loop, case, exit loop,
repeat until, if then, as well as the use of functions,
procedures and timer- and port interrupts. You
make an LED blink, build a time switch, measure a
potentiometer's wiper position, produce sounds,
suppress contact bounce, and control the brightness
of an LED. And of course you learn to debug r meani ng :
how to spot and fix errors in your programs,

284 pages * ISBN 978-1-907920-17-2
£29.50 * € 34.50 * US $47.60

MI FARE and Contactless Cards in Application

I RFID

MIFARE is the most widely used RFID technology, and
this book provides a practical and comprehensive
introduction to it. Among other things, the
initial chapters cover physical fundamentals,
relevant standards, RFID antenna design, security
considerations and cryptography. The complete
design of a reader's hardware and software is
described in detail. The reader's firmware and
the associated PC software support programming
using any .NET language. The specially developed
PC program, "Smart Card Magic, NET", is a simple

development environment that supports sending
commands to a card at the click of a mouse, as well
as the ability to create C# scripts. Alternatively, one
may follow all of the examples using Visual Studio
2010 Express Edition. Finally, the major smart card
reader API standards are introduced. The focus is on
programming contactless sm a rtcards using standard
PC/SC readers using C/C++, Java and C#.

484 pages * ISBN 978-1-907920-14-1
£44.90 * €49.90 * US $72.50

110 issues, more than 2,100 articles

t DVD Elektor
1 1990 through 1999

This DVD-ROM contains the full range of 1990-1999
volumes (all 110 issues) of Elektor Electronics magazine
(PDF), The more thar 2,100 separate articles have been
classified chronologically by their dates of publication
(month/year), but are also listed alphabetically by topic.
A comprehensive index enables you to search the entire
DVD. What's more, this DVD also contains the entire
The Elektor Datasheet Collection 1... 5' CD-ROM series,
with the original full datasheets of semiconductors,
memory ICs, microcontrollers, and much more.

ISBN 978-0-905705-76-7
£69.00 * € 89.00 • US $111.30

80 I November 2013 | www.elektor-magazine.com

Books, CD-ROMs, DVDs, Kits & Modules

: fTOafcal

Digital Signal Processing

o

X

* *

w.

X

0 r IlyaMm

©lektor

cftm

cmjw

Ultrasensitive wideband E-smog detector

E TAPIR Sniffs it Out!

Attention boy scouts, professionals and grandfathers!
This ultrasensitive wideband E-smog detector offers
you two extra senses to track down noise that's
normally inaudible. TAPIR — short for Totally Archaic
but Practical Interceptor of Radiation — also makes a
nice project to build: the kit comprises everything you
need. Even the enclosure, ingeniously consisting of the
PCB proper! Using the TAPIR is dead easy. Connect the
headphones and an antenna and switch it on. Move it
around any electrical device and you'll hear different
noises with each device, depending on the type and
frequency of the emitted field.

Kit of parts, incl. PCB

Art.# 120354-71

£13. 3G ■ C 14.95 • US $21.50

LabWorX 2

, Mastering Surface
Mount Technology

This book takes you on a crash course in techniques,
tips and know-how to successfully introduce surface
mount technology in your workflow, Even if you are
on a budget you too can jumpstart your designs
with advanced fine pitch parts. Besides explaining
methodology and equipment, attention is given to

5MT parts technologies and soldering methods. Many
practical tips and tricks are disclosed that bring
surface mount technology into everyone's reach
without breaking the bank. A comprehensive kit of
parts comprising all SMT components, circuit boards
and solder stencils is available for readers wishing to
replicate three projects described in this book.

282 pages • ISBN 978-1-907920-12-7
£29.50 • € 34.50 * US $47.60

Ideal reading for students and engineers

Practical

E Digital Signal Processing
using Microcontrollers

This book on Digital Signal Processing (DSP) reflects the
growing importance of discrete time signals and their

UK / ROW

Elektor International Media
78 York Street

London - W1H 1DP United Kingdom
Phone: +44 20 7692 8344
E-mail: service@elektor.com

use in everyday microcontroller based systems. The
author presents the basic theory of DSP with minimum
mathematical treatment and teaches the reader how
to design and implement DSP algorithms using popular
PIC microcontrollers. The author's approach is practical
and the book is backed with many worked examples
and tested and working microcontroller programs.
The book should be ideal reading for students at all
levels and for the practicing engineers who may want
to design and develop intelligent DSP based systems.
Undergraduate students should find the theory and
the practical projects invaluable during their final year
projects. Similarly, postgraduate students should be
able to develop advanced DSP based projects with the
aid of the book,

428 pages * ISBN 978-1-907920-21-9
£44.90 • C 49.90 * US $72.50

USA / CANADA

Elektor US

111 Founders Plaza, Suite 300
East Hartford, CT 06108 USA
Phone: 860.289.0800
E-mail: service@elektor.com

Further Information and Ordering: WWW. elektor. COITl/store

or contact customer service for your region

www.elektor-magazine.com | November 2013 | 81

Magazine

NEXT MONTH IN ELEKTOR MAGAZINE

FPGA Extension Board

Since its publication back in December 2012
thousands of readers have used the Elektor
FPGA board to delve into the possibilities of
programmable logic. This tiny board does
not have any peripheral circuitry, but that's
redressed with the presentation of an expansion
board that contains a comprehensive set of
peripheral components such as an LCD, various
buttons and LEDs, an A/D converter, an RGB
color sensor, a pressure sensor, a temperature
sensor and a GPS module.

Intelligent Network Tester

Faultfinding in an Ethernet network installed
at home or in the office is not always easy. In
such cases our Network Tester comes in handy.
The design is compact and consists mainly
of a single microcontroller and an Ethernet
connector. Three LEDs on the board show
whether a correct cable connection is available.
The same for the presence of an Internet
gateway, and if you are actually connected to
the Internet. A good alternative to expensive
commercial network analyzers!

DSP Entry-Level Board

If you want to start out with DSP you may be
at a loss where to start and what to choose
in terms of processor and software. This PCB
offers a simple and affordable entry level
opportunity into the DSP world. The board is
set up around the type ADAU17Q1 from Analog
Devices, Besides the DSP it contains just a few
components including six RCA connectors for
two audio inputs and four audio outputs, and
four potentiometers for controlling the output
signal levels.

Article titles and magazine contents subject to change, please check the Magazine tab at www.elektor.com
Elektor December 2013 is processed for mailing to US, UK and ROW Members starting November 12, 2013.

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Ordering Information

ORDERING INFORMATION

To order, contact customer service for your region:

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PLEASE NOTE: While we strive to provide the best
possible information in this issue f pricing and availability
are subject to change without notice. To find out about
current pricing and stock , please caff or email customer
service for your region ,

COMPONENTS

Components for projects appearing in Elektor are usually
available from certain advertisers in the magazine. If
difficulties in obtaining components are suspected, a
source will

normally be identified in the article. Please note, however,
that the source(s) given is (are) not exclusive.

TERMS OF BUSINESS

Shipping Note:

AH orders will be shipped from Europe, Please allow 2-4
weeks for delivery.

Returns

Damaged or miss-shipped goods may be returned for
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Call or email customer service to receive an RA# before
returning the merchandise and be sure to put the RA# on
the outside of the package. Please save shipping materials
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received 30 days from invoice.

Patents

Patent protection may exist with respect to circuits,
devices, components, and items described in our books,
magazines, online publications and presentations. Elektor
accepts no responsibility or liability for failing to Identify
such patent or other protection.

Copyright

All drawings, photographs, articles, printed circuit boards,
programmed integrated circuits, discs, and software
carriers published in our books and magazines (other
than in third-party advertisements) are copyrighted
and may not be reproduced (or stored in any sort of
retrieval system) without written permission from Elektor.
Notwithstanding, printed circuit boards may be produced
for private and educational use without prior permission.

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Elektor shall not be liable in contract, tort, or otherwise,
for any loss or damage suffered by the purchaser
whatsoever or howsoever arising out of, or In connection
with, the supply of goods or services by Elektor other than
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to refund the purchaser any money paid with respect to
the goods.

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www.elektor-magazine,com | November 2013 | 83

Need to Stay Connected?

Learn About Microchip's USB and Networking Solutions

USB

USB technology can be found in practically all applications and markets — from
consumer, industrial and automotive segments. The extreme proliferation of USB
has even led to the adoption of the technology as an embedded chip-to-chip high
bandwidth interface. Microchip has been enabling such uses, applications and markets
with seamless USB connectivity by delivering integrated value rich solutions, such as
USB hub controllers, power delivery and charging, transceivers/switches, Flash media
controllers and security.

Ethernet

Ethernet devices have become ubiquitous in communications and networking
products, servicing a wide variety of applications across multiple market segments.
This well understood technology provides a robust link to ensure reliable
communication between devices in a network. Microchip has a broad portfolio
of reliable, high quality and high performance Ethernet solutions. From Ethernet
Switches, Controllers, Bridges, and PHYs, to a variety of standard interfaces, serving
consumer, industrial, and automotive applications. Microchip can provide a solution
to address your varied application needs and offers you the support needed to reduce
your time to market.

GETTING STARTED IS EASY

If you need USB or Networking
connectivity in your product design,
Microchip's broad line of proven and
reliable solutions cover all main market
segments and applications including:

■ Consumer electronics

■ Mobile

■ Industrial equipment and control

■ Automotive

■ Medical

Visitwww.microchip.com /connectivity

for more information.

Microchip

Microcontrollers • Digital Signal Controllers • Analog * Memory * Wireless

The Microchip name and logo, the Microchip logo, dsPIC, M.PLAB and PiC are registered trademarks of Microchip Technology Incorporated in the U.SA and other countries. All other trademarks are the property of their registered owners,

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