William McNamara Wins the CC Code Challenge (Week 16)

We have a winner of last week’s CC Weekly Code Challenge, sponsored by IAR Systems! We posted a code snippet with an error and challenged the engineering community to find the mistake!

Congratulations to William McNamara of The Colony, Texas, USA for winning the CC Weekly Code Challenge for Week 16! William will receive a CC T-Shirt and one year digital subscription/renewal.

William’s correct answer was randomly selected from the pool of responses that correctly identified an error in the code. William answered:

Line 5: the “do” needs to be on a separate line or have a semicolon in front of it.


You can see the complete list of weekly winners and code challenges here.

What is the CC Weekly Code Challenge?
Each week, Circuit Cellar’s technical editors purposely insert an error in a snippet of code. It could be a semantic error, a syntax error, a design error, a spelling error, or another bug the editors slip in. You are challenged to find the error.Once the submission deadline passes, Circuit Cellar will randomly select one winner from the group of respondents who submit the correct answer.

Inspired? Want to try this week’s challenge? Get started!

Submission Deadline: The deadline for each week’s challenge is Sunday, 12 PM EST. Refer to the Rules, Terms & Conditions for information about eligibility and prizes.

CC279: What’s Ahead in the October Issue

Although we’re still in September, it’s not too early to be looking forward to the October issue already available online.

The theme of the issue is signal processing, and contributor Devlin Gualtieri offers an interesting take on that topic.

Gualtieiri, who writes a science and technology blog, looks at how to improve Improvig Microprocessor Audio microprocessor audio.

“We’re immersed in a world of beeps and boops,” Gualtieri says. “Every digital knick-knack we own, from cell phones to microwave ovens, seeks to attract our attention.”

“Many simple microprocessor circuits need to generate one, or several, audio alert signals,” he adds. “The designer usually uses an easily programmed square wave voltage as an output pin that feeds a simple piezoelectric speaker element. It works, but it sounds awful. How can microprocessor audio be improved in some simple ways?”

Gualtieri’s article explains how analog circuitry and sine waves are often a better option than digital circuitry and square waves for audio alert signals.

Another article that touches on signal processing is columnist Colin Flynn’s look at advanced methods of debugging an FPGA design. It’s the debut of his new column Programmable Logic in Practice.

“This first article introduces the use of integrated logic analyzers, which provide an internal view of your running hardware,” O’Flynn says. “My next article will continue this topic and show you how hardware co-simulation enables you to seamlessly split the verification between real hardware interfacing to external devices and simulated hardware on your computer.”

You can find videos and other material that complement Colin’s articles on his website.

Another October issue highlight is a real prize-winner. The issue features the first installment of a two-part series on the SunSeeker Solar Array Tracker, which won third SunSeekerplace in the 2012 DesignSpark chipKit challenge overseen by Circuit Cellar.

The SunSeeker, designed by Canadian Graig Pearen, uses a Microchip Technology chipKIT Max32 and tracks, monitors, and adjusts PV arrays based on weather and sky conditions. It measures PV and air temperature, compiles statistics, and communicates with a local server that enables the SunSeeker to facilitate software algorithm development. Diagnostic software monitors the design’s motors to show both movement and position.

Pearen, semi-retired from the telecommunications industry and a part-time solar technician, is still refining his original design.

“Over the next two to three years of development and field testing, I plan for it to evolve into a full-featured ‘bells-and-whistles’ solar array tracker,” Pearen says. “I added a few enhancements as the software evolved, but I will develop most of the additional features later.”

Walter Krawec, a PhD student studying Computer Science at the Stevens Institute of Technology in Hoboken, NJ, wraps up his two-part series on “Experiments in Developmental Robotics.”

In Part 1, he introduced readers to the basics of artificial neural networks (ANNs) in robots and outlined an architecture for a robot’s evolving neural network, short-term memory system, and simple reflexes and instincts. In Part 2, Krawec discusses the reflex and instinct system that rewards an ENN.

“I’ll also explain the ‘decision path’ system, which rewards/penalizes chains of actions,” he says. “Finally, I’ll describe the experiments we’ve run demonstrating this architecture in a simulated environment.”

Videos of some of Krawec’s robot simulations can be found on his website.

Speaking of robotics, in this issue columnist Jeff Bachiochi introduces readers to the free robot control programming language RobotBASIC and explains how to use it with an integrated simulator for robot communication.

Other columnists also take on a number of very practical subjects. Robert Lacoste explains how inexpensive bipolar junction transistors (BJTs) can be helpful in many designs and outlines how to use one to build an amplifier.

George Novacek, who has found that the cost of battery packs account for half the DIY Battery Chargerpurchase price of his equipment, explains how to build a back-up power source with a lead-acid battery and a charger.

“Building a good battery charger is easy these days because there are many ICs specifically designed for battery chargers,” he says.

Columnist Bob Japenga begins a new series looking at file systems available on Linux for embedded systems.

“Although you could build a Linux system without a file system, most Linux systems will have some sort of file system,” Japenga says. “And there are various types. There are files systems that do not retain their data (volatile) across power outages (i.e., RAM drives). There are nonvolatile read-only file systems that cannot be changed (e.g., CRAMFS). And there are nonvolatile read/write file systems.”

Linux provides all three types of file systems, Japenga says, and his series will address all of them.

Finally, the magazine offers some special features, including an interview with Alenka Zajić, who teaches signal processing and electromagnetics at Georgia Institute of Technology’s School of Electrical and Computer Engineering. Also, two North Carolina State University researchers write about advances in 3-D liquid metal printing and possible applications such as electrical wires that can “heal” themselves after being severed.

For more, check out the Circuit Cellar’s October issue.



Jesper Poulsen Wins the CC Code Challenge (Week 15)

We have a winner of last week’s CC Weekly Code Challenge, sponsored by IAR Systems! We posted a code snippet with an error and challenged the engineering community to find the mistake!

Congratulations to Jesper Poulsen of København, Denmark for winning the CC Weekly Code Challenge for Week 15! Jesper will receive a CCGold Issues Archive.

Jesper’s correct answer was randomly selected from the pool of responses that correctly identified an error in the code. Jesper answered:

Line 23: Should be 0..@list-2 to avoid array overrun when taking $list[$i+1]


You can see the complete list of weekly winners and code challenges here.

What is the CC Weekly Code Challenge?
Each week, Circuit Cellar’s technical editors purposely insert an error in a snippet of code. It could be a semantic error, a syntax error, a design error, a spelling error, or another bug the editors slip in. You are challenged to find the error.Once the submission deadline passes, Circuit Cellar will randomly select one winner from the group of respondents who submit the correct answer.

Inspired? Want to try this week’s challenge? Get started!

Submission Deadline: The deadline for each week’s challenge is Sunday, 12 PM ESTRefer to the Rules, Terms & Conditions for information about eligibility and prizes.

CC278: New Issue, New Look, New Media

Over the years, Circuit Cellar editors have learned you simply can’t stand still when your magazine focuses on ever-evolving embedded electronics. So with the September issue, we introduce a dramatic redesign to make the magazine’s look more contemporary and its connection with our website stronger.

The heart of our content is still project pieces and columns. For example, in this issue, Nelson Epp writes about a Rubik’s Cube-solving robot (p. 24), Walter Krawec examines evolving neural networks in robotics (p. 42), and Brian Millier describes how to configure his “Iso-Pi” I/0 board for the Raspberry Pi single-board computer (p. 32).

In addition, our column topics include examining different battery types and their characteristics (p. 48), exploring commodity LED characteristics with a stress tester and an optical output detector (p. 54), and understanding BMP graphical file formats (p. 64).

Speaking of columnists, the September issue introduces a new one—Ayse Coskun, a Boston University assistant professor. Her bimonthly Green Computing column will focus on topics that recognize energy is a “first-order constraint” on any computing system, large or small. So she will be looking at everything from energy-efficient software and hardware-design strategies to electricity cost savings and battery-life extension (p. 60).

Another new feature is CC World (p. 8), which will provide monthly updates on topics of interest to the magazine’s international community of engineers, academics, and students. This month, we touch on the CC Weekly Code Challenge and the designers participating in Elektor-LABS.com, the lab-tested, project-sharing site provided by Elektor International Media (EIM).

But our changes are not simply about what you see on the magazine’s pages. This redesign makes it easier for you to connect our print content to related material at circuitcellar.com.

At the end of each article, you’ll discover an easier way to find project files and supporting documents online. You can either type circuitcellar.com/ccmaterials in your browser or use your smartphone to scan the printed QR code.

We hope you enjoy the new look and conveniences.

Ayse Coskun and Green Computing

Green computing can mean different things to different people—and interests.

Environmental organizations tend to embrace the definition of green computing that stresses practices that lead to efficient and eco-friendly use of computing resources.

But businesses are also interested in green computing, particularly when it creates energy efficiencies that reduce their costs.

So, the topic is a hot one. And with that in mind, next month Circuit Cellar will introduce a bimonthly Green Computing column written by Ayse Coskun.

Coskun, who has MS and PhD degrees in Computer Science and Engineering, is an assistant professor in the Electrical and Computer Engineering Department at Boston University. Her research interests include temperature and energy management, 3-D stack architectures, computer architecture, and embedded systems. You can find out even more about her by checking out our interview published in July 2012.

Coskun will address a wide range of topics in her columns. “I will be writing about energy-efficient software and hardware design strategies, opportunities for electricity cost savings and battery-life extension, system-level policies for energy and thermal management, and smart infrastructures for improving efficiency,” she says.

Her September column focuses on energy-efficient cooling strategies for servers, which require striking a balance between cooling energy and leakage power. “You can reduce the cooling energy used by enabling the processor temperatures to rise within safe limits, “ she says.  “However, leakage power increases at high temperatures and can cause excessive energy waste. “

Her column explains how  to experimentally analyze the trade-off between a server’s cooling and leakage and how to use that analysis to design energy-efficient cooling strategies—not only for servers, but for computing systems in general.

For more details, be sure to check out her debut column in the September issue.

An experimental setup for enabling customized fan control for a commercial server.



Microcontroller-Based, Cube-Solving Robot

Cube Solver in ActionCanadian Nelson Epp has earned degrees in physics and electrical engineering. But as a child, he was stumped by the Rubik’s Cube puzzle. So, as an adult, he built a Rubik’s Cube-solving robot that uses a Parallax Propeller microcontroller and a 52-move algorithm to solve the 3-D puzzle.

Designing and completing the robot wasn’t easy. Epp says he originally used a “gripper”-type robot that was “a complete disaster.” Then he experimented with different algorithms–“human memorizable ones”—before settling on a solution method developed by mathematician Morwen Thistlethwaite. (The algorithm is based on the mathematical concepts of a group, a subgroup, and generator and coset representatives.)

Nelson also developed a version of his Rubik’s Cube solver that used neural networks to analyze the cube’s colors, but that worked only half the time.

So, considering the time he had to spend on project trial and error (and his obligations to work, family, and pets), it took about six years to complete the robot. He writes about the results in the September issue of Circuit Cellar magazine. 

Here, he describes some of the choices he made in hardware components.

“The cube solver hardware uses two external power supplies: 5 VDC for the servomotors and 12 VDC for the remaining circuits. The 12-VDC power supply feeds a Texas Instruments (TI) UA78M33 and a UA78M05 linear regulator. The UA78M05 regulator powers an Electronics123 C3088 camera board. The UA78M33 regulator powers a Maxim Integrated MAX3232 ECPE RS-232 transceiver, a Microchip Technology 24LC256 CMOS serial EEPROM, remote reset circuitry, the Propeller, a SD/MMC card, the camera board’s digital output circuitry, and an ECS ECS-300C-160 oscillator. The images at right show my cube solver and circuit board.
“The ECS-300C-160 is a self-contained dual-output oscillator that can produce clock signals that are binary fractions of the 16-MHz base signal. My application uses the 8- and 16-MHz clock taps. The Propeller is clocked with the 8-MHz signal and then internally multiplied up to 64 MHz. The 16-MHz signal is fed to the camera.

“I used a MAX3232 transceiver to communicate to the host’s RS-232 port. The Propeller’s serial input pin and serial output pin are only required at startup. After the Propeller starts up, these pins can be used to exchange commands with the host. The Propeller also has pins for serial communication to an EEPROM, which are used during power up when a host is not sending a program.

“The cube-solving algorithm uses the coset representative file stored on an SD card, which is read by the Propeller via a SparkFun Electronics Breakout Board for SD-MMC cards. The Propeller interface to the SD card consists of a chip select, data in, data out, data clock, and power. The chip select is fixed into the active state. The three lines associated with data are wired to the Propeller.

“The Propeller uses a camera to determine the cube’s starting permutation. The C3088 uses an Electronics123 OV6630 color sensor module. I chose the camera because its data format and clocking speed was within the range of the Propeller’s capabilities. The C3088 has jumpers for external or internal clocking.”

To read more about Epp’s design journey—and outcomes—check out Circuit Cellar’s September issue. And click here for a video of his robot at work.


CC 277: Simulate and Design a Switched Capacitor Filter

Here is Lacoste’s experimental mockup. It’s not pretty, but it’s functional. The clock is at the top. The filter is below.

Circuit Cellar columnist Robert Lacoste doesn’t like to throw away his old magazines—at least the ones that have electronics projects.

And often it’s the lack of microcontrollers in such projects that he finds intriguing. The designs required “clever solutions to implement even simple features, which is always a good source of inspiration,” he says.

Lacoste was recently inspired by a 1981 Elektor magazine article on switched-capacitor filters (part of the old magazine collection in his basement). So, he decided to revisit the topic in his column appearing in Circuit Cellar’s August issue.

“I figured, why not refresh it for a Circuit Cellar Darker Side article, as mastering switched-capacitor filters is now mandatory for plenty of mixed-signal designs?”

Lacoste’s column shows you how to modify a basic low-pass filter into a switched-capacitor filter.

He explains why such a modification can be a good one:

“The most basic form of a low-pass filter is the simple one-pole RC filter… Why can’t we be happy with such simple RC filters? There are two reasons. First, it is often convenient to have a filter with an adjustable cutoff frequency. With a RC filter, you would need to change either the resistor’s or the capacitor’s value. This it is not easy to do if you want to design an inexpensive electronic system. The other reason is more linked to IC technology and CMOS in particular.

“Assume you want to design a filtering chip with a cutoff frequency of about 10 kHz. If you want to use a small and inexpensive capacitor—perhaps no more than 1 nF—you will need a high-value resistor… The problem is that designing a high-value resistor on a silicon chip is complicated (i.e., expensive). Moreover, unlike capacitors, on-chip resistors are difficult to manufacture with tight specifications.”

Lacoste found the solution by looking through few back issues of his magazine collection and a few past decades.

“In the late 1970s, IC designers looked for a way to replace high-value resistors with inexpensive and easy-to-integrate parts (e.g., small capacitor),” he says.

The idea of replacing a resistor with a switched capacitor produced the switched-capacitor architecture Lacoste presents in his August column. As a bonus, his design offers an easy way to adjust switching frequencies.

“Of course, no one is actually designing a switched-capacitor circuit from scratch, as I did for this article,” Lacoste says. “It was only for demonstration purposes. There are plenty of ready-made switched-capacitor chips on the market. Just read their datasheets and use them in your design, more or less as a black box.”

Still, Lacoste says, “the best way to learn is to never be afraid of any technology. Knowing the internals helps you avoid usage mistakes.”

Intrigued? Check out Lacoste’s column in the August issue for more details.

LED Characterization: An Arduino-Based Curve Tracer

Circuit Cellar columnist Ed Nisley doesn’t want to rely solely on datasheets to understand the values of LEDs in his collection. So he built a curve tracer to measure his LEDs’ specific characteristics.

Why was he so exacting?

“Most of the time, we take small light-emitting diodes for granted: connect one in series with a suitable resistor and voltage source, it lights up, then we expect it to work forever,” he says in his July column in Circuit Cellar. “A recent project prompted me to take a closer look at commodity 5-mm LEDs, because I intended to connect them in series for better efficiency from a fixed DC supply and in parallel to simplify the switching. Rather than depend on the values found in datasheets, I built a simple Arduino-based LED Curve Tracer to measure the actual characteristics of the LEDs I intended to use.”

The Arduino Pro Micro clone in this hand-wired LED Curve Tracer controls the LED current and measures the resulting voltage.

Ed decided to share the curve tracer with his Circuit Cellar readers.

“Even though this isn’t a research-grade instrument, it can provide useful data that helps demonstrate LED operation and shows why you must pay more attention to their needs,” he says.

Ed says that although he thinks of his circuit as an “LED Curve Tracer,” it doesn’t display its data.

“Instead, I create the graphs with data files captured from the Arduino serial port and processed through Gnuplot,” he says. “One advantage of that process is that I can tailor the graphs to suit the data, rather than depend on a single graphic format. One disadvantage is that I must run a program to visualize the measurements. Feel free to add a graphics display to your LED Curve Tracer and write the code to support it!”

He adds that “any circuit attached to an Arduino should provide its own power to avoid overloading the Arduino’s on-board regulator.”

“I used a regulated 7.5 VDC wall wart for both the Arduino Pro Mini board and the LED under test, because the relatively low voltage minimized the power dissipation in the Arduino regulator,” he says. “You could use a 9 VDC or 12 VDC supply.”

To read more about Ed’s curve tracer, check out Circuit Cellar’s July issue.


CC 276: MCU-Based Prosthetic Arm with Kinect

In its July issue, Circuit Cellar presents a project that combines the technology behind Microsoft’s Kinect gaming device with a prototype prosthetic arm.

The project team and  authors of the article include Jung Soo Kim, an undergraduate student in Biomedical Engineering at Ryerson University in Toronto, Canada, Nika Zolfaghari, a master’s student at Ryerson, and Dr. James Andrew Smith, who specializes in Biomedical Engineering at Ryerson.

“We designed an inexpensive, adaptable platform for prototype prosthetics and their testing systems,” the team says. “These systems use Microsoft’s Kinect for Xbox, a motion sensing device, to track a healthy human arm’s instantaneous movement, replicate the exact movement, and test a prosthetic prototype’s response.”

“Kelvin James was one of the first to embed a microprocessor in a prosthetic limb in the mid-1980s…,” they add. “With the maker movement and advances in embedded electronics, mechanical T-slot systems, and consumer-grade sensor systems, these applications now have more intuitive designs. Integrating Xbox provides a platform to test prosthetic devices’ control algorithms. Xbox also enables prosthetic arm end users to naturally train their arms.”

They elaborate on their choices in building the four main hardware components of their design, which include actuators, electronics, sensors, and mechanical support:

“Robotis Dynamixel motors combine power-dense neodymium motors from Maxon Motors with local angle sensing and high gear ratio transmission, all in a compact case. Atmel’s on-board 8-bit ATmega8 microcontroller, which is similar to the standard Arduino, has high (17-to-50-ms) latency. Instead, we used a 16-bit Freescale Semiconductor MC9S12 microcontroller on an Arduino-form-factor board. It was bulkier, but it was ideal for prototyping. The Xbox system provided high-level sensing. Finally, we used Twintec’s MicroRAX 10-mm profile T-slot aluminum to speed the mechanical prototyping.”

The team’s goal was to design a  prosthetic arm that is markedly different from others currently available. “We began by building a working prototype of a smooth-moving prosthetic arm,” they say in their article.

“We developed four quadrant-capable H-bridge-driven motors and proportional-derivative (PD) controllers at the prosthetic’s joints to run on a MC9S12 microcontroller. Monitoring the prosthetic’s angular position provided us with an analytic comparison of the programmed and outputted results.”

A Technological Arts Esduino microcontroller board is at the heart of the prosthetic arm design.

The team concludes that its project illustrates how to combine off-the-shelf Arduino-compatible parts, aluminum T-slots, servomotors, and a Kinect into an adaptable prosthetic arm.

But more broadly, they say, it’s a project that supports the argument that  “more natural ways of training and tuning prostheses” can be achieved because the Kinect “enables potential end users to manipulate their prostheses without requiring complicated scripting or programming methods.”

For more on this interesting idea, check out the July issue of Circuit Cellar. And for a video from an earlier Circuit Cellar post about this project, click here.


CC275: Build a Signal Frequency Counter

In the June issue of Circuit Cellar, George Adamidis, a physicist and electronics engineer from Greece, shares his design for a 1.5-GHz frequency counter.

His design is based on an 8-bit microcontroller, but his modifications enable using the device as a 28-bit counter.

Here is a picture of the complete project.

“This design began as a Microchip Technology 8-bit PIC learning project. But it became more than that,” Adamidis says in his article. “Although I used an 8-bit PIC, I actually created a 28-bit counter.”

“The device measures signal frequencies from 0.1 Hz to 1.5 GHz and displays them on a 2 × 16 character LCD,” Adamidis continues. “It offers a frequency resolution up to 0.1 Hz for frequencies in the 0.1-Hz-to-100-MHz range and up to 4 Hz for 100-MHz-to-1.5-GHz frequencies. (The display resolution generally differs from the measurement accuracy.) Minimum and maximum hold functions, selection of frequency units, and gate time adjustment are also supported. “

Adamidis says it is “remarkable” that his frequency counter is actually a 28-bit counter.

“It uses a Microchip Technology PIC18F2620 microcontroller, which has only 16-bit internal counters. I used the PIC18F2620’s internal 16-bit Timer0 module (configured as a 16-bit counter), an additional 4-bit NXP Semiconductors 74F161 binary counter, and the PIC18F2620’s internal prescaler (in 1:256 prescale mode) in series to achieve a total of 28 bits.”

This is the 1.5-GHz frequency counter’s block diagram.


To read more about  the theory of operation, hardware, and software behind Adamidis’s design, check out this month’s issue of Circuit Cellar.

DIY Single-Board Computers

Countless technological innovations have certainly made the earliest personal  computers long obsolete. As Circuit Cellar contributors Oscar Vermeulen and Andrew Lynch note:  “Today there is no sensible use for an 8-bit, 64-KB computer with less processing power than a mobile phone. “

Nonetheless, there exists a “retrocomputing”  subculture that resurrects older computer hardware and software in DIY projects. It may be sentimental, but it can also be instructive.

In their two-part series beginning in July in Circuit Cellar, Vermeulen and Lynch focus on that strain of retrocomputing that involves designing and building your own computer system from a “bag of chips” and a circuit board.

Part 1 describes a simple single-board CP/M design that uses just one high-capacity RAM chip and is compatible with a serial or PC terminal.

Here is a homebrew N8VEM system with a single-board computer (SBC) and disk/IDE card plugged into the ECB backplane.

“It is easy to create a functional computer on a little circuit board—considering all the information now available on the Internet,” Vermeulen and Lynch say in Part 1.  “These retro machines may not have much practical use, but the learning experience can be tremendously valuable.”

Some “homebrewed” computer creations  can be “stunningly exotic,” according to Vermeulen and Lynch, but most people build simple machines.

“They use a CPU and add RAM, ROM, a serial port, and maybe an IDE interface for mass storage. And most hobbyists run either BASIC (e.g., the 1980s home computers) or use a “vintage” OS such as CP/M.

“Running CP/M, in fact, is a nice target to work toward. A lot of good software ensures your homebrew computer can do something interesting once it is built. As the predecessor of MS-DOS, CP/M also provides a familiar command-line interface. And it is simple. A few days of study are enough to port it to your circuit board.”

But some Circuit Cellar readers may want more from a retrocomputing experience than a one-off project.  In that case, there are online resources that can help, according to the authors.

“Working on your own, it can become progressively more difficult to take the next steps (i.e., building graphics subsystems or using exotic processors) or to add state-of-the-art microcontrollers to create ‘Frankenstein’ systems (i.e., blends of old and new technology that can do something useful, such as automate your home).”

Part 1 of their article introduces a solid online resource for taking retrocomputing to the next level–the N8VEM Google group, which provides a single-board CP/M design meant to engage others.

This is the N8VEM in its $20 stand-alone incarnation.

“N8VEM is not about soldering kits. It is about joining in, trying new things, and picking up skills along the way. These skills range from reading schematics to debugging a computer card that does not operate as intended. The learning curve may be steep at times, but, because the N8VEM mail group is very active, expert help is available if or when you get stuck….

“As the novelty of designing a simple single-board computer (SBC) wears off, you may prefer to focus your energy on exploring graphics systems or ways to hook up 8-bit machines on the Internet. Or, you may want to jump into systems software development and share your experiences with a few hundred others.

“Retrocomputing is not always backward-facing. Making  ‘Frankenstein’ systems by adding modern Parallax Propeller chips or FPGAs to old hardware is a nice way to gain experience in modern digital electronics, too.”

For more, check out the July issue of Circuit Cellar for Part 1 of their series. In Part 2, scheduled for publication in August,  the authors provide a technical look at the N8VEM’s logic design. It also provides a starting point for anyone interested in exploring the N8VEM’s system software and expansion hardware, according to Vermeulen and Lynch.



CC275: Shape The Future

In January, Circuit Cellar introduced a new section, Tech the Future, which dedicates page 80 of our magazine to the insights of innovators in groundbreaking technologies.

We’ve reached out to a number of graduate students, professors, researchers, engineers, designers, and entrepreneurs, asking them to write short essays on their fields of expertise, with an emphasis on future trends.

Their topics have included high-speed data acquisition, Linux home automation, research into new materials to replace traditional silicon-based CMOS for circuitry design, control system theory for electronic device DIYers, and how open-source hardware will make world economies more democratic and efficient.

Our contributors have been diverse in more than just their topics. They have been talented

Tech the Future essayist Fergus Dixon designed this DNA sequencer, the subject of an article in the May 2013 issue of Circuit Cellar.

young researchers and seasoned professionals. Male and female. American, Portuguese, Italian, Indian, and Australian.

The one thing they have in common? They keep a close eye on the ever-changing landscape of technological change. And their essays have helped our readers focus on what to watch. We compensate authors for the essays we choose to publish, and we are eager to hear your suggestions on subjects for Tech the Future.

If you are an innovator interested in writing an essay for Tech the Future, e-mail me (editor@circuitcellar.com) with the topic you’d like to address and some information about yourself. If you are a reader who wants to hear from someone in particular through Tech the Future or has a suggestion for an essay topic, please contact me.

The work of those we’ve featured so far can be found online at circuitcellar.com/category/tech-the-future. Here are just a few of the innovators you will find there:

Maurizio Di Paolo Emilio, a designer of data acquisition software for physics-related experiments and industrial applications, discussing the future of data acquisition technology.

Saptarshi Das, a nano materials researcher who holds a PhD in Electrical Engineering from Purdue University, focusing on the urgent need for alternatives to silicon-based CMOS. These alternative materials, now the subject of extensive scientific research, will be game changers for the microelectronics and nanoelectronics industries, he says.

Fergus Dixon, an Australian entrepreneur and designer of the popular software program “Simulator for Arduino,” explaining why open-source hardware is a valuable tool in the development of new medical devices. Design opportunities for such devices are countless. Hot technologies developed for 3-D printing and unmanned aerial vehicles (UAVs) have direct medical applications, including 3-D-printed prosthetic ears and nanorobots that utilize UAV technology.

Enjoy these articles and others online. In the meantime, I’ll be checking my e-mail for what you would like to see featured in Tech the Future.

Electrical Engineer Crossword (Issue 275)

The answers to Circuit Cellar’s June electronics engineering crossword puzzle are now available.


2.    UNIFIEDMODELING—Language that standardizes software specifications
3.    KELVINBRIDGE—Compares low resistance values [two words]
6.    THINCLIENT—A codependent program [two words]
10.    BANANAPLUG—Makes electrical connections [two words]
11.    CONDENSER—aka capacitor
13.    ASTABLE—A multivibrator circuit
15.    FLIPFLOP—A fundamental building block [two words]
18.    AMMETER—Used to calibrate current
19.    CLOCKGATING—Method of lowering dynamic power dissipation [two words]
20.    THERMIONICVALVE—Uses a vacuum to control electric current [two words]


1.    VISITORPATTERN—Keeps an algorithm away from an object structure
4.    RUNTIME—Multi-lingual computer system
5.    FIELDEFFECT—This type is unipolar [two words]
7.    LISSAJOUSCURVE—An oscilloscope trace [two words]
8.    NONMASKABLE—Cannot be ignored
9.    CASCODECIRCUIT—Provides amplification [two words]
12.    CRON—Keeps things on schedule
14.    ROENTGEN—Radiation measurement
16.    RETFIE—Instruction that enables new interrupts to occur
17.    SELSYN—aka mag-slip

New Products: June 2013

C-Programmable Autonomous Mobile Robot System

The RP6v2 is a C-programmable autonomous mobile robot system designed for hobbyists and educators at universities, trade schools, and high schools. The system includes a CD with software, an extensive manual, plenty of example programs, and a large C function library. All library and example programs are open-source GNU general public license (GPL).

The autonomous mobile robot system has a large payload capacity and expansion boards, which may be stacked as needed. It receives infrared (IR) codes in RC5 format and includes integrated light, collision, speed, and IR-obstacle sensors. Its powerful tank drive train can drive up steep ramps and over obstacles.

The RP6v2’s features include an Atmel ATmega32 8-bit RISC microcontroller, AVR-GCC and RobotLoader open-source software for use with Windows and Linux, six PCB expansion areas, two 7.2-VDC motors, an I2C bus expansion system, and a USB interface for easy programming and communication.
The fully assembled RP6v2 robotic system costs $199.

Global Specialties

Smart Panels with Powerful CPU and Multiple OS Support

The SP-7W61 and the SP-1061 smart panels are based on the Texas Instruments 1-GHz Sitara AM3715 Cortex-A8 processor and an Imagination Technologies integrated PowerVR SGX graphics accelerator. The products support multiple OSes—including Linux 2.6.37, Android 2.3.4, and Windows Compact 7—making them well suited for communications, medical and industrial control, human-machine interface (HMI), and transportation applications.

The SP-7W61 (7” and 16:9) and the SP-1061 (10” and 4:3) have a low-power, slim, fanless mechanical design and a high-value cost/performance (C/P) panel PC module that uses powerful and efficient components. Compared with other x86 HMI or open-frame products, the SP-7W61 and the SP-1061 successfully keep power consumption to less than 5.9 W, which is half the typical rate. The smart panels feature multiple display sizes and low power consumption options. They can be implemented into slim and thin chassis types (e.g., for HMI, control panels, or wall-mount controllers).

ADLINK provides full support on software customization based on different platforms. A virtual machine or software development kit (SDK) is provided with related documentation for different platforms, so users can easily set up the software environment.
Contact ADLINK for pricing.

ADLINK Technology, Inc.

Fast-Switching 0.65-TO-20-GHz Synthesizer

The APSYN420B is a 0.65-to-20-GHz frequency synthesizer with a 0.001-Hz resolution and 0.1° phase resolution. The synthesizer provides a nominal output power of 13 dBm into 50 ?. The module features a high-stability internal reference that can be phase-locked to a user-configurable external reference or used in a master-slave configuration for high phase coherence.

The APSYN420B’s key features include low phase noise, fast switching (settling time is typically 20 µs with a 20-µs frequency update), and an internal OCXO reference that can be configured for high phase coherence between multiple sources. The synthesizer offers USB and LAN interfaces and consumes less than 10 W when powered from an external 6-VDC supply.

The APSYN420B’s modulation capabilities include angle, pulse, pulse trains, and pulsed chirps. Linear, logarithmic, or random-frequency sweeps can be performed with combined modulation running. Frequency chirps (linear ramp, up/down) can also be accomplished. The device can accept external reference signals from 1 to 250 MHz.

Applications for the APSYN420B include automatic test equipment, satellite, and other telecommunications needs. The APSYN420B is designed for a 0°C-to-45°C operating temperature range and weighs less than 2 lb in a compact 2.4” × 4.2” × 8.3” enclosure.
Contact Saelig for pricing.

Saelig Co., Inc.

SoC for Next-Generation Multimedia and Navigation Systems

The R-Car H2 is the latest member of Renesas’s R-Car series of automotive system-on-a-chip (SoC) offerings. The SoC delivers more than 25,000 Dhrystone million instructions per second (DMIPS) and provides high-performance and state-of-the-art 3-D graphics capabilities for high-end multimedia and automotive navigation systems.
The R-Car H2 is powered by the ARM Cortex A-15 quad-core configuration running an additional ARM Cortex A-7 quad core. The SoC also features Imagination Technologies’s PowerVR Series6 G6400 graphics processing unit (GPU). The GPU supports open technologies (e.g., OpenGL ES 2.0) and the OpenGL ES 3.0 and OpenCL standards.
The R-Car H2’s bus architecture includes dedicated CPU and IP caches, which reduce the double data rate type three (DDR3) memory bandwidth consumption. To ensure adequate memory bandwidth, the R-Car H2 is equipped with two independent DDR3-1600 32-bit interfaces.

The R-Car H2 integrates advanced automotive interfaces including Ethernet audio video bridging (AVB), MOST150, and CAN and mass storage interfaces such as serial advanced technology attachment (SATA), USB 3.0/2.0, secure digital (SD) card, and PCI Express for system expansion. As a device option, the GPS baseband engine handles all modern navigation standards. The R-Car H2’s additional features include 24-bit digital signal processing (DSP) for codec, high-quality audio processing with hardware sample rate converters, and audio mixing. Its multi-core architecture enables you to implement real-time features (e.g., quick-boot, backup camera support, and media processing) parallel to the execution of advanced OSes, such as QNX Neutrino RTOS, Windows Embedded Automotive, or Linux.

The SoC’s media hardware accelerators enable features such as 4× HD 1080p video encoding/decoding including Blu-ray support at 60 frames per second, image/voice recognition, and high-resolution 3-D graphics with almost no CPU load. These implemented hardware modules also execute the display content improvements needed for HMI/navigation data similar to movie/DVD handling.
Contact Renesas for pricing.

Renesas Electronics Corp.

KNX Device Control

The KNX Gateway enables HAI by Leviton’s Omni and Lumina Ethernet-based controllers to communicate with and control KNX devices through KNX’s standardized network communications bus protocol. You can use an HAI by Leviton interface or automated controller programming to control KNX devices (e.g., lighting devices, temperature and energy management, motors for window coverings, shades, and shutters) in homes and businesses.

The KNX Gateway maps specific data points of each KNX device to a unit or thermostat number on the HAI by Leviton controller. The interface between the KNX Gateway and the HAI by Leviton controller utilizes a RS-485 serial connection.

Compatible controllers include HAI’s OmniPro II home-control system, Omni IIe, Omni LTe, Lumina Pro, and Lumina. The KNX Gateway is powered by either a power over Ethernet (PoE) connection or a 12-to-24-V AC/DC converter.
Contact Leviton for pricing.

Leviton Manufacturing Co., Inc.

DC/DC Controller Uses Only a Single Inductor

The LTC3863 is a high-voltage inverting DC/DC controller that uses a single inductor to produce a negative voltage from a positive-input voltage. All of the controller’s interface signals are positive ground referenced. None of the LTC3863’s pins are connected to a negative voltage, enabling the output voltage to be limited by only the external components selection.

Operating over a 3.5-to-60-V input supply range, the LTC3863 protects against high-voltage transients, operates continuously during automotive cold crank, and covers a broad range of input sources and battery chemistries. The controller helps increase the runtime in battery-powered applications.

It has a low 70-µA quiescent current in Standby mode with the output enabled in Burst Mode operation. The LTC3863’s output voltage can be set from –0.4 to 150 V or lower at up to 3 A typical, making it well suited for 12-or-24-V automotive, heavy equipment, industrial control, telecommunications, and robotic applications.

The LTC3863 drives an external P-channel MOSFET, operates with a selectable fixed frequency between 50 and 850 kHz, and is synchronizable to an external clock from 75 to 750 kHz. Its current-mode architecture provides easy loop compensation, fast transient response, cycle-by-cycle overcurrent protection, and excellent line regulation. Output current sensing is accomplished by measuring the voltage drop across a sense resistor.
The LTC3863’s additional features include programmable soft start or tracking, overvoltage protection, short-circuit protection, and failure mode and effects analysis (FMEA) verification for adjacent pin opens and shorts.

The LTC3863 is offered in 12-pin thermally enhanced MSOP and 3-mm × 4-mm QFN packages. The controllers cost $2.06 in 1,000-unit quantities.

Linear Technology Corp.

Enhanced Web-Based Monitoring Software

HOBOlink is a web-enabled software platform that provides 24/7 data access and remote management for Onset Computer’s web-based HOBO U30 data logging systems. The software’s enhanced version enables users to schedule automatic delivery of exported data files in CSV or XLSX format, via e-mail or FTP.

HOBOlink can configure exported data export in a customized manner. For example, a user with four HOBO U30 systems measuring multiple parameters may configure HOBOlink to automatically export temperature data only. The time range may also be specified.

HOBOlink also enables users to easily access current and historical data, set alarm notifications and relay activations, and manage and control HOBO U30 systems without going into the field. An application programming interface (API) is available to organizations that want to integrate energy and environmental data from HOBOlink web servers with custom software applications.
Contact Onset for pricing.

Onset Computer Corp.

Digitally Tunable Capacitors for LTE Smartphones

Peregrine Semiconductor expanded its DuNE digitally tunable capacitor (DTC) product line with six second-generation devices for antenna tuning in 4G long-term evolution (LTE) smartphones. The PE623060, PE623070, PE623080, and PE623090 (PE6230x0) DTCs have a 0.6-to-7.7-pF capacitance range and support main antenna power handling of up to 34 dBm. The PE621010 and the PE621020 (PE6210x0) DTCs have a 1.38-to-14-pF capacitance range and are optimized for power handling up to 26 dBm, making them well suited for diversity antennas. The highly versatile devices support a variety of tuning circuit topologies, particularly impedance-matching and aperture-tuning applications.
The PE6230x0 DTCs are optimized for key cellular frequency bands from 700 to 2,700 MHz, featuring direct battery voltage operation with consistent performance enabled by on-chip voltage regulation.

The 5-bit, 32-state PE623060/70/80 DTCs have a 0.9-to-4.6-pF capacitance range. The 4-bit, 16-state PE623090 DTC has a 0.6-to-2.35-pF capacitance range. The PE623090 DTC’s lower minimum capacitance solves a critical problem in high-frequency tuning. The 5-bit, 32-state PE6210x0 DTCs support the 100-to-3,000-MHz frequency range. These DTCs extend the range of diversity antennas and improve data rates by optimizing the antenna performance at the operating frequency. The PE621010 DTC has a 1.38-to-5.90-pF capacitance range.

The PE6230x0 and PE6210x0 product families enable designers to develop smaller, higher-performing antennas. The product’s antenna-tuning functions—including bias generation, integrated radio frequency (RF) filtering and bypassing, control interface, and electrostatic discharge (ESD) protection of 2-kV human body model (HBM)—are incorporated into a slim, 0.55-mm × 2-mm × 2-mm package. All decoding and biasing are integrated on-chip, and no external bypassing or filtering components are required.
Contact Peregrine for pricing.

Peregrine Semiconductor Corp.

A Real-Time Fuel Consumption Monitor

Jeff Bachiochi’s real-time fuel consumption monitor for his Jeep.

Circuit Cellar columnist Jeff Bachiochi has enjoyed driving his wife’s Prius, in part because of the real-time feedback it gives him on the miles per gallon he is getting. It made him aware of how he could save gas with simple and immediate adjustments to his driving style.

With that in mind, he thought it would be a good idea to build an effective and affordable monitoring device that would give him the same real-time mpg for his Jeep.  After all, he can’t always borrow his wife’s car.

In the June issue, he shares what he came up with for an onboard diagnostics display. He explains below how he tapped into his own experience, as well as that of another Circuit Cellar author, to build the device for Jeep

“In the summer of 2011, I presented a three-part series about the on-board diagnostic system (OBD-II) built into every automobile produced since 1996 (Circuit Cellar 251–253)….”

“In 2005, Bruce D. Lightner wrote an article about his winning entry in the 2004 Atmel AVR design contest (“AVR-Based Fuel Consumption Gauge,” Circuit Cellar 183, 2005). Lightner’s project altered an analog tachometer gauge as a display for miles per gallon. I wanted to show a little more information, so my project uses a Parallax Propeller microcontroller to interrogate the OBD interpreter and drive a composite LCD.

“You can get a composite color display from Parallax or an online source. While I had a small 2.5” display to work with, I was looking for something a bit bigger. For less than $50, I found a 7” LCD, which happened to be combined with a camera (for mounting on a vehicle’s rear license plate frame)…

“I dug out my Propeller Proto Board and blew off the dust…. The Propeller microcontroller design includes eight 32-bit parallel processors (i.e., cogs) and peripheral support, including access to the 32 I/O pins, two counters, and a video generator per cog.  It is the video generator support that makes this project possible with a minimal component count…. only three resistors are required to develop a composite video output.“

To read more about Bachiochi’s OBD device, check out his article in the June issue.