The Future of Open-Source Hardware for Medical Devices

Medical technology is changing at a rapid pace, but regulatory compliance is also becoming increasingly harder. Regulatory compliance can act as a barrier to innovation, but it is a necessary check to ensure quality medical care. For small companies, aligning innovation with regulatory compliance can only help.

Fergus Dixon

When designing any new product, the FDA-recommended process is a great reference. First, the design input requirements must be written down. After the device has been designed and prototyped, verification and validation (V&V) will ensure that the device meets the design input. The device is then documented, creating the design output or device master record (DMR). Each device made is checked against the DMR and documented in the device history record (DHR). So all the details on how to make the device are contained in the DMR, and the results and traceability are recorded in the DHR.

My company recently asked an overseas company to design and manufacture an existing product. After many e-mails, the overseas company managed to build a working unit and immediately requested an order for 1,000. Before ordering even one unit, there was the matter of V&V. So what is V&V? Verification is the act of ensuring that the circuit acts as it should, as the circuit designer intended. This involves testing to a predetermined criteria, where the pass/fail is clearly defined. Testing happens by varying the inputs and checking the outputs to test the device as close to 100% as reasonably possible. When the inputs fall outside a normal range (e.g., a 10-VDC instead of 12-VDC battery voltage), the device must still work or it must provide a message showing why the device will not work (e.g., low battery light). Validation is the act of ensuring the circuit works as the customer or patient requires. This involves field testing, feedback, and rework—lots of it.

Working for medical device companies can be very rewarding. Smaller companies tend to work at the cutting edge. Larger companies are more secure and have stable products, but they can be less agile. With one company, we had a device that used smart batteries. During testing, we discovered that the batteries would not charge below 15ºC. After many meetings and e-mails to the manufacturers, the problem went to management, who decided to change the manual to say: “Do not charge below 15ºC.” Smaller dynamic companies can attract the best scientists, which is great until a connector fails and there is a roomful of highly intelligent people with no soldering iron experience. Every technology company can benefit from having at least one experienced technician or engineer. A few hours spent playing with an Arduino is a great way to get this experience.

What about open-source hardware (OSHW) for medical devices? For home hobbyists and students, OSHW is great. There is free access to working circuits, programs, and sketches. C compilers, which once cost several thousand dollars, are mostly free. For the manufacturers, the benefits are plenty of feedback, which can be used to improve products. There is one roadblock, and that involves the loss of intellectual property (IP), which means anyone can copy the hardware. Creative Commons has addressed this with an agreement that any copies must reference the original work. Closed-source hardware can also be good and present fewer issues with losing IP. Apple is a great example. Rather than use feedback to improve products, it makes smart decisions about future products. The iOS vs. Android battle can be viewed as a closed-source vs. open-source struggle that still hasn’t produced a winner. Medical devices and OSHW will have to meet up sometime.

Fergus Dixon’s embedded DNA sequencer project (Source: F. Dixon)

What about the future of medical devices? Well, the best is yet to come with brighter organic light-emitting diode (OLED) displays, a multitude of wireless connectivity options (all using the serial interface), and 32-bit ARM cores. DNA is gradually being unlocked with even “junk DNA” becoming meaningful. The latest hot topics of 3-D printing and unmanned aerial vehicles (UAVs) have direct medical applications with 3-D printed prosthetic ears and medical nanorobotics ready to benefit from UAV technology. Using a new sensor (e.g., a gyroscope) now means visiting an online seller such as Pololu, which offers ready-built development kits at reasonable prices. A recent design was a manually assisted CPR device project, which was abandoned due to lack of funding. How great would it be to have a device that could not only improve the current 10% survival rate with CPR (5% without CPR) but also could measure a patient’s health to determine whether CPR was helping and, even more importantly, when to stop administering it? Now that would be a good OSHW project.

Member Profile: Gordon David Dick

Gordon Dick

Location: Stony Plain, AB, Canada (Stony Plain is suburb of Edmonton, home of the Oilers)

Education: MS, the University of Saskatchewan in Saskatoon, SK, Canada

Occupation: Gordon is semi-retired. He used to be an Electronics Technology and Computer Engineering Technology instructor at the Northern Alberta Institute of Technology in Edmonton.

Member Status: Gordon says he used to have Circuit Cellar issues dating back to 1995. “We were getting issues under the ‘college program’ then,” he explained. Later, his department subscribed to the magazine and the issues came directly to Gordon. Then he obtained a personal subscription. “I still have my paper copies containing my own articles. And we bought the CDs to get all the back issues.”

Technical Interests: Gordon has always been interested in electronics, both as a hobby and as a profession. He focused first on audio, then turned to microcontrollers. He has built a few microcontroller-based instruments, some of which have been the topics of his Circuit Cellar articles. “For a time, I was involved in building microcontroller-based dog training equipment. I built a microcontroller-based weather station, which I also wrote an article about. I have several microcontroller-based projects in my home that are specific to my needs. My cold-room temperature controller is microcontroller-based, for example.”

Most Recent Embedded Tech-Related Acquisition: Gordon bought a SparkFun Electronics FG085 frequency generator kit.

Current Projects: He is working with a Freescale Semiconductor MPL3115 pressure/temperature I2C transducer for his weather station. “It has amazing barometric pressure resolution,” Gordon explained.

Q&A: Michael Hamilton (Engineering and Entrepreneurship)

Michael Hamilton

Michael Hamilton has been designing microcontroller-based systems for 25 years. Over the past 10 years, he has spearheaded two companies: A&D Technologies, which supplies wireless temperature and humidity controllers, and Point & Track, which provides data-gathering apps and other business intelligence tools. In January, I interviewed Michael about his longtime interest in electronics, his first microcontroller design, his award-winning Renesas Electronics RL78 project, and his praise for 3-D printers.—Nan Price, Associate Editor

NAN: Where are you located?

MICHAEL: Lewisville, TX.

NAN: Give us some background information. Did anything specific spark your interest in engineering?


MICHAEL: My dad was an instrument repairman for Ashland Refinery in Canton, OH. As part of his training, he brought home his electronics trainer along with the instruction manuals.

When I was 13, I was interested in explosives and I needed an electronic timer for safety reasons. I studied his coursework and figured out how to build a timer using the famous 555 timer chip.

My family had a Christmas tree farm, where I spent many hours working. This led me to the decision that I needed to go to college instead of doing hard labor. I ended up going to Ohio University in Athens, OH, to study chemical engineering.

The reason I chose chemical engineering was, during high school I entered the science fair with a project called the “Distillation of Crude Oil.” This project was very successful as I made it to the state science fair and won lots of prizes.

Tektronix 485 oscilloscope

After I graduated from college, my interest turned back to electrical engineering and I started reading every book I could find on electronics. I remember my first big electronics purchase was a Tektronix 485 oscilloscope.

While working for Ashland Chemical in clean room environments, I realized there was a need for an accurate humidity controller. This led me to design my own temperature and humidity controller and form my first company, A&D Technologies ( in 2003.

NAN: What types of products and services does your company provide?


MICHAEL: A&D Technologies supplies wireless temperature and humidity controllers (e.g., HTC100) along with custom control panels. Using the latest technology, the control panels communicate to the outside world using SMS texting via cellular modems and e-mail via Ethernet.

Along with another partner, we created a new company, Point & Track (, which provides custom data-gathering apps for mobile devices such as iPhone and Android, secure database management, and business intelligence tools used to analyze collected data. The company also provides the ability to export geographic information system (GIS) data directly to customer-owned databases.

NAN: What type of work did you do prior to A&D Technologies and Point & Track?

MICHAEL: I was a project engineer who designed and installed automated equipment such as a fully automatic coiling systems using an ABB robot.

NAN: How long have you been designing microcontroller-based systems?

MICHAEL: Twenty-five years.

NAN: What was the first microcontroller you worked with?

MICHAEL: It was Microchip Technology’s PIC18F84. I designed a laser viscometer that was used to determine the viscosity of plastic resins while working for Ashland Chemical in Los Angeles, CA. I learned how easy it was to provide precise timing and work with digital I/O. It was so much easier than trying to work with individual integrated circuit (IC) chips.

NAN: What is the worst problem you have encountered with embedded microcontrollers?

MICHAEL: By far, the worst issue has to do with electromagnetic interference (EMI) from nearby devices, such as switching of solenoids or transformers. An extensive amount of time is spent designing PCBs so they will be immune to the external environment. Things like ground planes, metal oxide varistor (MOVs), transient voltage suppressors (TVSes), and capacitor/resistor networks are used to minimize the susceptibility of the microcontrollers, but it seems like you can never predict the environment for these kinds of issues. Maybe someone will write an article discussing these issues and how to prevent them.

NAN: Any recent tech purchases?

MICHAEL: I recently purchased a Rigol Technologies DSA-815-TG spectrum analyzer. This device is a must have, right behind the oscilloscope. It enables you to see all the noise/interference present in a PCB design and also test it for EMI issues.

NAN: Do you have any other unique tools on your workbench?

CNC Machine

MakerBot 3-D Printer

MICHAEL: I have a three-axis CNC machine and a MakerBot 3-D printer. I use the CNC machine to cut out enclosures and the 3-D printer to create bezels for LCDs and also to create 3-D prototypes. These machines are extremely useful if you need to make any precise cuts or if you want to create 3-D models of future products.

NAN: What is the fastest way to learn about programming and electronics?

MICHAEL: In the last six months, I have learned the following languages: Arduino, PHP, HTML 5, CSS, MySQL, Android, JavaScript, and jQuery. This was done by watching YouTube videos while exercising at the gym.

NAN: Your project, the Cloud Electrofusion Machine, recently won second prize in the 2012 RL78 Green Energy Challenge. Tell us about your project and your contest-entry process.

Cloud Electrofusion

MICHAEL: The project created an in-expensive and energy-efficient way to weld polyethylene pipe together. Commercial machines cost around $4,000. This machine can be built for less than $200. It utilizes a light dimmer to drop the voltage from 110 to 40 VAC and controls the amount of time that the power is applied to a coil inside an electrofusion fitting. By incorporating a barcode scanner, all the specific properties of the fitting can be easily entered into the microcontroller. Then, after the fusion is complete, all the data is sent to a cloud server via a wireless cellular modem.

The RL78 was very easy to use and program. I really didn’t have many problems with the design.

NAN: Your article “Infrared Radiation Measurement: FFT Double-Beam Infrared Spectrophotometer” (Circuit Cellar 229, 2009) describes a spectrophotometer built around a Microchip Technology dsPIC30F4012 digital signal controller. How does the microcontroller work in the design?

MICHAEL: The project created an instrument to identify chemical substances by using infrared spectroscopy. The dsPIC30F4012 uses a 10-bit ADC to measure the infrared radiation signal that passes through a chemical substance. Then the microcontroller computes the fast Fourier transform (FFT) of the signal. This creates a table of amplitude versus frequency. The amplitude is then scaled to provide a relative transmittance. This information is serially transmitted over USB to a computer for plotting. This USB interface is accomplished using a PIC18F2450.

NAN: Are you currently working on or planning any microprocessor-based projects?

MICHAEL: We are currently working on a cloud fusion logger. This device reads all the data from the welding process in the field and transmits it to a cloud server. Later, the data can be analyzed and reports can be generated. A Raspberry Pi is used as the embedded controller. It is very fast and easy to use since it is based on Linux. We are working on getting the Android operating system loaded so existing code can be used and it will interface well with an Android smartphone, which will be used as the operator interface.

NAN: What do you consider to be the “next big thing” in the embedded design industry?

MICHAEL: One of the issues with embedded controllers is how to maintain the firmware and fix bugs after the devices are installed in the field. Using various wireless technologies, the devices will be automatically updated. Smartphones already use this technology.

CC273: Necessity and Invention

Tom Cantrell wanted to stop fiddling with his sprinklers as he tried to balance conserving water in California and keeping his lawn green. So he asked himself if he could craft a weather-savvy sprinkler controller.

In the April issue of Circuit Cellar, he describes how to weatherize an embedded app. He uses a Texas Instruments MSP430 microcontroller and a WIZnet W5200 smart Ethernet chip to access National Weather Service forecasts and data (p. 36).

Engineer and entrepreneur Michael Hamilton also has found that necessity breeds invention—which in turn can start a new business. “While working for Ashland Chemical in clean room environments, I realized there was a need for an accurate humidity controller,” he says. “This led me to design my own temperature and humidity controller and form my first company, A&D Technologies.”

In our interview, he talks about what he has done since, including founding another company and becoming an award-winning designer in the RL78 Green Energy Challenge (p. 44).

A shift in the timing signal—or jitter—of a digital transmission can adversely affect your high-speed designs. It’s been an issue for at least 40 years, with the advent of the first all-digital telecommunications networks such as PDH. But you may not have dealt with it in your designs. In the April magazine, Robert Lacoste explains how to diagnose a case of the jitters (p. 54).

Jeff Bachiochi isn’t a musician. But he didn’t need to be one to work with the musical instrument digital interface (MIDI), which relays instructions on how to play a piece directly to an instrument (bypassing the musician). In the April issue, he describes the circuitry needed to connect to MIDI communication and display messages between devices (p. 60).

Atmel’s ATmega88 and ATmega1284 microcontrollers are at the heart of the CNC controller.

Also, Brian Millier describes how he built a microcontroller-based G-code controller for a CNC router. Even if you are not interested in building such a controller, you can learn from the techniques he used to provide the multi-axis stepper-motor motion (p. 30).

You also might find Scott Weber’s experience instructive. After placing microcontroller-based devices throughout his home, he found he needed a control panel to enable him to update the devices and check on their operation. He shares his panel’s basic structure and its software design. Its display shows him all the information he needs (p. 22).

While wear and tear affect the reliability of hardware, software reliability is different. Whatever causes software to fail is built-in, through errors ranging from poor coding to typos to omissions. On page 51, George Novacek shares some methods of calculating the probability of faults in your firmware.

Also in the April issue, Bob Japenga continues looking at concurrency in embedded systems. In the sixth article of his series, he discusses two Linux mechanisms for creating embedded systems—POSIX FIFOs and message queues (p. 48).

Finally, “From the Archives” features a 2003 article by Mark Balch about Verilog HDL. He discusses how to use it in your custom logic designs for digital systems (p. 68).

SMD Stencil Reflow Soldering Tutorial

Surface-mount SMD reflow soldering doesn’t have to be difficult. All you need is a solder paste stencil, a hot air gun, and a little know-how. No reflow oven necessary!

Dave Jones, of, covers everything you need to know in the following easy-to-understand SMD stencil reflow soldering tutorial.

The kit is available via Elektor’s partner, Eurocircuits.

The Eurocircuits kit includes all the essential SMT components, circuit boards, and solder stencils.

For SMT info and additional projects, refer to Vincent Himpe’s book, Mastering Surface Mount Technology (Elektor). is an Elektor International Media website.

Open-Source Hardware for the Efficient Economy

In the open-source hardware development and distribution model, designs are created collaboratively and published openly. This enables anyone to study, modify, improve, and produce the design—for one’s own use or for sale. Open-source hardware gives users full control over the products they use while unleashing innovation—compared to the limits of proprietary research and development.

This practice is transforming passive consumers of “black box” technologies into a new breed of user-producers. For consumers, open-source hardware translates into better products at a lower cost, while providing more relevant, directly applicable solutions compared to a one-size-fits-all approach. For producers, it means lower barriers to entry and a consequent democratization of production. The bottom line is a more efficient economy—one that bypasses the artificial scarcity created by exclusive rights—and instead focuses on better and faster development of appropriate technologies.

Open-source hardware is less than a decade old. It started as an informal practice in the early 2000s with fragmented cells of developers sharing instructions for producing physical objects in the spirit of open-source software. It has now become a movement with a recognized definition, specific licenses, an annual conference, and several organizations to support open practices. The expansion of open-source hardware is also visible in a proliferation of open-source plans for making just about anything, from 3-D printers, microcontrollers, and scientific equipment, to industrial machines, cars, tractors, and solar-power generators.

As the movement takes shape, the next major milestone is the development of standards for efficient development and quality documentation. The aim here is to deliver on the potential of open-source products to meet or exceed industry standards—at a much lower cost—while scaling the impact of collaborative development practices.

The Internet brought about the information revolution, but an accompanying revolution in open-source product development has yet to happen. The major blocks are the absence of uniform standards for design, documentation, and development process; accessible collaborative design platforms (CAD); and a unifying set of interface standards for module-based design—such that electronics, mechanical devices, controllers, power units, and many other types of modules could easily interface with one another.

Can unleashed collaboration catapult open-source hardware from its current multimillion dollar scale to the next trillion dollar economy?

One of the most promising scenarios for the future of open source hardware is a global supply chain made up of thousands of interlinked organizations in which collaboration and complementarity are the norm. In this scenario, producers at all levels—from hobbyists to commercial manufacturers—have access to transparent fabrication tools, and digital plans circulate freely, enabling them to build on each other quickly and efficiently.

The true game changers are the fabrication machines that transform designs into objects. While equipment such as laser cutters, CNC machine tools, and 3-D printers has been around for decades, the breakthrough comes from the drastically reduced cost and increased access to these tools. For example, online factories enable anyone to upload a design and receive the material object in the mail a few days later. A proliferation of open-source digital fabrication tools, hackerspaces, membership-based shops, fab labs, micro factories, and other collaborative production facilities are drastically increasing access and reducing the cost of production. It has become commonplace for a novice to gain ready access to state-of-art productive power.

On the design side, it’s now possible for 70 engineers to work in parallel with a collaborative CAD package to design the airplane wing for a Boeing 767 in 1 hour. This is a real-world proof of concept of taking development to warp speed—though achieved with proprietary tools and highly paid engineers. With a widely available, open-source collaborative CAD package and digital libraries of design for customization, it would be possible for even a novice to create advanced machines—and for a large group of novices to create advanced machines at warp speed. Complex devices, such as cars, can be modeled with an inviting set of Lego-like building blocks in a module-based CAD package. Thereafter, CNC equipment can be used to produce these designs from off-the-shelf parts and locally available materials. Efficient industrial production could soon be at anyone’s fingertips.

Sharing instructions for making things is not a novel idea. However, the formal establishment of an open-source approach to the development and production of critical technologies is a disruptive force. The potential lies in the emergence of many significant and scalable enterprises built on top of this model. If such entities collaborate openly, it becomes possible to unleash the efficiency of global development based on free information flows. This implies a shift from “business as usual” to an efficient economy in which environmental and social justice are part of the equation.


Catarina Mota is a New York City-based Portuguese maker and open-source advocate who cofounded the openMaterials ( research project, which is focused on open-source and DIY experimentation with smart materials. She is both a PhD candidate at FCSHUNL and a visiting scholar at NYU, and she has taught workshops on topics such as hi-tech materials and simple circuitry. Catarina is a fellow of the National Science and Technology Foundation of Portugal, co-chair of the Open Hardware Summit, a TEDGlobal 2012 fellow, and member of NYC Resistor.

Marcin Jakubowski graduated from Princeton and earned a PhD Fusion Physics from the University of Wisconsin. In 2003 Marcin founded the Open Source Ecology ( network of engineers, farmers, and supporters. The group is working on the Global Village Construction Set (GVCS), which is an open-source, DIY toolset of 50 different industrial machines intended for the construction of a modern civilization (

This essay appears in Circuit Cellar 271, February 2013.

RL78 Challenge Winner’s Workspace in Lewisville, TX

Lewisville, TX-based electrical engineer Michael Hamilton has been a busy man. During the past 10 years, he created two companies: A&D Technologies, which supplies wireless temperature and humidity controllers, and Point & Track, which provides data-gathering apps and other business intelligence tools. And in his spare time, he designed a cloud electrofusion machine for welding 0.5″ to 2″ polyethylene fittings. It  won Second Prize in the 2012 Renesas RL78 Green Energy Challenge.

In an interview slated for publication in Circuit Cellar 273 (April 2013), Hamilton describes some of his projects, shares details about his first microcontroller design, and more.

Michael Hamilton in his workspace. Check out the CNC machine and 3-D printer.

During the interview process, he also provided a details about his workspace, in which he has a variety of interesting tools ranging from a CNC machine to a MakerBot 3-D printer. Hamilton said:

I have a three-axis CNC machine and MakerBot 3-D printer. I use the CNC machine to cut out enclosures and the 3-D printer to create bezels for LCDs and also to create 3-D prototypes. These machines are extremely useful if you need to make any precise cuts or if you want to create 3-D models of future products.

Hamilton also noted:

I recently purchased a Rigol Technologies DSA-815-TG spectrum analyzer. This device is a must-have, right behind the oscilloscope. It enables you to see all the noise/interference present in a PCB design and also test it for EMI issues.

Michael Hamilton’s test bench and DSA815

He has a completely separate area for PCB work.

A separate space for PCB projects

Overall, this is an excellent setup. Hamilton clearly has a nice collection must-have EE tools and test equipment, as well as a handy CNC machine and decent desktop storage system. The separate PCB bench is a great feature that helps keep the space orderly and clean.

As for the 3-D printer, well, it’s awesome.

New Products: March 2013

Universal PCB Test System

SaeligThe ABI BoardMaster 8000 PLUS is a versatile, self-contained, and easy-to-use PCB test system. The system, which is manufactured by ABI Electronics, comprises a comprehensive set of test instruments, including a built-in PC, for testing and faultfinding on almost any type of PCB.

The BoardMaster 8000 PLUS test system is well suited for applications including telecommunications, transportation, and automotive manufacturing. The system is used by land, air, and naval forces to provide on-site test and repair.

The BoardMaster 8000 PLUS is an integrated package of high-specification instrumentation controlled by sophisticated but easy-to-use software. The hardware is installed in a rugged transportable case that also contains a high-specification Windows PC. The BoardMaster 8000 PLUS is based on a modular, customizable system. Its software can be configured to guide users step-by-step through a test procedure with custom-annotated picture images, instructions, and attached datasheets to provide quick Pass/Fail results.

A typical BoardMaster 8000 PLUS configuration includes two board fault locator modules, with 128 test channels for multiple test methods for fault diagnosis and functional testing of digital ICs, IC connections status, voltage acquisition, and V-I curve testing of components on unpowered boards. The PCB test system also includes an analog IC tester for in-circuit functional testing of analog ICs and discrete components (i.e., no programming or circuit diagrams needed) and a fully configurable V-I tester for detection of faults on unpowered boards.

The BoardMaster 8000 PLUS test system features a multiple instrument station with eight high-specification test and measurement instruments in one compact module (frequency counter, digital storage oscilloscope, function generator, digital floating multimeter, auxiliary PSU, and universal I/O) and a triple-output variable power supply that provides required supply voltages to the unit under test.

Contact Saelig for pricing.

Saelig Co., Inc.

ABI Electronics, Ltd.

Small, Low-Cost Antenna

The compact MicroSplatch embedded antenna utilizes Linx Technologies’s simulation tools and provides performance similar to the standard Splatch antenna while only utilizing one third of the circuit board’s space.

The MicroSplatch is reflow-compatible and capable of withstanding oven temperatures up to 260°C. The antenna is available in 2.4-GHz and 403-, 418-, 433-, 868-, and 916-MHz bands. The antenna is well suited for remote controls, pagers, and compact data transmission devices.

The MicroSplatch antenna can be easily added to your design. You simply need a footprint for the antenna and an associated proximity ground plane.

The affordable MicroSplatch antenna is priced for cost-sensitive applications. Contact Linx for pricing.

Linx Technologies

FEM for Smart Energy/Advanced Metering Infrastructure & ISM Band Applications

The RFFM6403 is a highly-integrated front-end module (FEM) for smart energy/advanced metering infrastructure (AMI) applications. The single-chip RFFM6403 FEM reduces customer design time and speeds customer time-to-market for portable battery-powered equipment, general 433-/470-MHz ISM-band systems, and smart energy/AMI applications operating in the 405-to-475-MHz frequency range.

The feature-rich RFFM6403 integrates a transmit high-power path with a 30.5-dBm PA and Tx harmonic output filtering a transmit bypass through path with Tx harmonic output filtering, and a receive path with a low-noise amplifier (LNA) with bypass mode. The FEM also features a low insertion loss/high-isolation SP3T switch and separate Rx/Tx 50-Ω ports, which simplifies matching and provides input and output signals for both the Tx and Rx paths.

The RFFM6403 is designed for AMI systems operating with high-efficiency requirements and a minimum output power of 30 dBm. In the receive path, the Rx chain provides 16 dB of typical gain with only 5 mA of current and a 1.7-dB noise figure. The FEM’s small form factor (6 mm × 6 mm × 1 mm) minimizes product footprint and reduces the external component count and associated assembly costs.

Contact RF Micro Devices for pricing.

RF Micro Devices, Inc.

Compact Buck Converter for High-Voltage Applications

The LTC3646 is a 40-V input synchronous buck converter capable of delivering up to 1 A of continuous output current from a 3-mm × 4-mm DFN-14 (or thermally enhanced MSOP16) package. The converter operates from a 4-to-40-V input voltage range. It is well suited for automotive and industrial applications requiring high-voltage input capability, high efficiency, and fast switching frequencies for small-solution footprints.

The LTC3646 utilizes controlled on-time architecture capable of stepping inputs as high as 36 V down to 3.3 V. It features switching frequencies in excess of 2 MHz, which keeps switching noise out of critical frequency bands (e.g., AM radio). The converter can deliver fast transient response, even with duty cycles less than 10%. Its internal synchronous rectification delivers efficiencies as high as 95% and requires only 140 µA of quiescent current, which maximizes battery run time.

The LTC3646’s internal switching frequency can be programmed between 200 kHz and 3 MHz or synchronized to an external clock. The combination of high efficiency and only 140 µA of quiescent current offers high efficiency over a broad load range. For noise-sensitive applications, the LTC3646 can be used in forced continuous operation to minimize voltage ripple.

The standard LTC3646 offers a 2-to-30-V output range. The LTC3646-1 offers a 0.6-to-15-V output range. Both versions feature internal soft-start, internal or external compensation, and robust short-circuit protection.

Pricing for the LTC3646EDE/-1 and LTC3646EMSE/-1 starts at $2.85 each in 1,000-unit quantities. Pricing for the extended-temperature (I grade) versions (i.e., the LTC3646IDE/-1 and LTC3646IMSE/-1) starts at $3.14 each in 1,000-unit quantities. Pricing for the high-temperature (H grade) options (i.e., the LTC3646HDE/-1 and LTC3646HMSE/-1) starts at $3.39 each in 1,000-piece quantities.

Linear Technology Corp.

Four-Quadrant PWM Servo Controller

The ESCON 36/3 EC is a four-quadrant PWM servo controller capable of controlling brushless DC motors with Hall sensors up to approximately 100 W. It features a digital current controller with a large bandwidth for optimal motor current/torque control and drift-free speed, which enables a 0-to-150,000-rpm speed range. The ESCON 36/3 EC features fully configurable digital and analog inputs and outputs and can run in various operating modes including speed controller (closed and open loop) and current controller.

The compact servo controller is controlled by an analog set value. This value can be specified by analog voltage, an external or internal potentiometer, a defined value, or a PWM signal with a variable duty cycle. The controller can enable or disable the power stage depending on the rotation’s direction, or it can use speed ramps for acceleration and deceleration. Hall sensors can be used to regulate the speed.

When the servo controller is connected to a PC via a USB port, it can be easily configured with the “ESCON Studio” graphical user interface (GUI). You can use a variety of functions during startup and while configuring the inputs and outputs, monitoring, data recording, and diagnostics. Assistance is provided by user-friendly software wizards and an automatic procedure for fine tuning the controller is also available.

The ESCON 36/3 EC features circuits that protect against overcurrent, excess temperature, under- and over-voltage, voltage transients, and short circuits in the motor cable. It is equipped with protected digital inputs and outputs and an adjustable current limitation to protect the motor and the load. The analog output voltage can be used to monitor the motor current and the motor shaft’s actual speed. The large range for the input voltage and the operating temperature enables the ESCON 36/3 EC to be used in a variety of drive applications.

Contact maxon for pricing.

maxon motor

Modules Provide Flexible & Practical Digital I/O Functionality

The USB-7230 and USB-7250 isolated USB digital I/O modules are designed for I/O expansion or portable applications. Each module features a high-speed frequency/event counter, a digital filter, and change of state (COS) detection in a single USB module that supports high-voltage control and monitoring applications’ flexibility and reliability requirements.

The USB-7230 provides 32-channel isolated digital I/O and two-channel frequency/event counters. The USB-7250 provides eight-channel solid-state relay output (four-form C and four-form A), eight-channel isolated digital input, and two-channel frequency/

event counters. The modules feature high-voltage on/off control and monitoring and isolation voltage support up to 2,500 VRMS. They also include integrated frequency/event counting and COS detection via the built-in complex programmable logic device (CPLD). A programmable digital filter removes unexpected glitches from input channels to efficiently monitor the I/O status.

The USB-7230 and USB-7250 modules feature USB power, removable screw-down terminals for simplified connection, and multifunctional stands for fast and easy desktop-, rail-, or wall-mounting. They also include lockable USB cables to secure connectivity. The USB modules simplify device ID settings with a rotary control that identifies the active module in multiple-connection configurations.

The USB-7230 and USB-7250 modules include ADLINK’s U-Test application, which is a free, ready-to-use testing program that delivers out-of-the-box configuration and generates simple functions to get the platform up and running. With U-Test, no programming is required for full data monitoring, logging, and FFT analysis. As with all ADLINK USB digital I/O devices, the USB-7230 and USB-7250 are compatible with National Instruments’s LabVIEWTM, MathWorks’s MATLAB, and Microsoft Visual Studio and Visual Studio.NET.

Contact ADLINK for pricing.

ADLINK Technology, Inc.

High-Efficiency Stepper Motor Driver IC

The LV8702V is a stepper motor driver integrated circuit (IC) designed to reduce overall power consumption. The motor driver also helps reduce heat generation, vibration, and noise from motors in office automation equipment applications (e.g., copiers, scanners, and multifunction printers).

The stepper motor driver IC uses driver waveform monitoring to detect motor conditions. It reduces power consumption by automatically reducing the current value according to the rotation speed or motor load. The stepper motor has a 9-to-32-V operating voltage range. Protection features include output short protection, a thermal shutdown function, and a step-out detection function. The LV8702V’s advanced functions include stall detection, step-loss, and current drive optimization.

The LV8702V is available in a 5.6-mm × 15-mm SSOP44J package. The motor costs $6 per unit in 2,000-quantity units.

ON Semiconductor

Pressure Sensors for Flow Measurement in Bypass Configuration

The SDP601 and SDP611 sensors are differential pressure sensors specifically calibrated to measure mass flow in a bypass configuration. A bypass configuration is well suited for applications where individually adapted flow channels are necessary or where small differential pressures must be measured with high precision (e.g., HVAC applications, which often involve large flow volume measurement).

Bypass configurations use an orifice or a linear-flow restrictor to generate a differential pressure in a flow channel. This pressure is measured over the orifice or the linear flow component. The difference between the pressures before and after the orifice correlates to the volumetric flow in the channel, depending on the specific characteristics of the flow restriction component. Therefore, the mass flow can be calculated from the measured pressure drop (i.e., differential pressure) over the orifice.

The SDP601 and SDP611 sensors expand Sensirion’s product range of digital differential pressure sensors in the SDP600 series. Along with the other products in this series, these sensors provide a digital I2C output and are fully calibrated and temperature compensated. Like all devices in the SDP600 series, the SDP6x1 sensors are available in two versions. The SDP601 is designed for direct threaded connection to a pressure manifold with O-ring sealing. The SDP611 is designed for tube connection.

Contact Sensirion for pricing.


Single-Board Retrocomputer

The CGCOLORMAX is a single-board retrocomputer that supports add-on Arduino Shields and runs a modern implementation of the BASIC programming language. The board has connections for color video (i.e., video graphics array) output and a PS/2 keyboard input. An SD card socket on the front of the board provides the “floppy drive” for program and data storage.

A stereo music synthesizer, an Arduino Shield interface, and a battery-backed clock are included on The CGCOLORMAX. Hardware interfacing is available as 20 I/O lines on the rear connector and 20 lines on the Arduino Shield connector. This versatile design enables you to easily interface to serial, SPI, I2C, 1-wire, and other circuits.

The CGCOLORMAX also includes a bootloader that enables firmware updating and comes preloaded with BASIC. The board can be tethered to a PC/Mac via a USB cable and programmed via a serial terminal. The USB connection can also provide power to the board.

The CGCOLORMAX can operate as a stand-alone computer by supporting a keyboard and a VGA monitor. The board can be powered by any 8-to-18-V AC or DC power supply. The default BASIC program can be automatically loaded from internal or SD card memory.

Contact CircuitGizmos for pricing.

CircuitGizmos, LLC

Optimized Compiler with Advanced Debug Capabilities

A complete integration with the Eclipse IDE—IAR Systems’s integrated development environment (IDE)—is available for IAR Embedded Workbench for ARM, the high-performance development tool suite. With this integration, IAR offers Eclipse support as an alternative to the IAR Embedded Workbench IDE, which enables its customers to use its build tools and debugger within the Eclipse IDE.

While the proprietary IAR Embedded Workbench IDE is tailor-made for embedded development, intuitive, and easy-to-use, the open-source Eclipse IDE provides flexibility through its extensible framework and its ability to interoperate with a large ecosystem of supplementary tools.

The full integration of the IAR C-SPY debugger replaces the GDB-based debugger that is standard with Eclipse, and enables IAR Systems’ debug technology to be fully exploited from within the Eclipse IDE. C-SPY’s debug functionality includes a timeline window that graphically correlates visualizations of interrupt logs, data logs, power samples, and user-defined events plotted against time. C-SPY supports ARM’s Embedded Trace Macrocell (ETM) and its Embedded Trace Buffer (ETB). Power profiling enables fine-tuning of an application’s power consumption, and the C-SPY Trace window displays detailed trace data.

In addition to all standard Eclipse CDT (C/C++ development tooling) functionality, the integration enables additional features (e.g., project import functionality, stepping on function call level, and complex code and data breakpoints).

Contact IAR for pricing.

IAR Systems

Advanced Video Annotation Controller

The eVAC2000 is a real-time NTSC/PAL video overlay and video annotation controller for the PCI/104 bus. The controller features a high-resolution graphics accelerator, a digital NTSC/PAL TV decoder, a digital NTSC/PAL TV encoder, and a video overlay controller, which are all contained within a single PC104 card. The eVAC2000 is well suited for applications requiring titles, dynamic grids, or visible watermarking.

The eVAC2000 accepts up to four composite NTSC or PAL analog video inputs, from inputs including video cameras, digital video recording equipment, and video instrumentation. It is capable of mixing video and graphics data or mixing two separate video channels, and can provide output to drive a video graphics array (VGA) monitor, a TV monitor, or a TMDS/LVDS flat-panel display. The eVAC2000 video annotation controller features multi-format, alpha-blending, hardware-enabling graphics/video and video/video to be alpha-blended over gradations from transparent to fully opaque.

The high-throughput, low-latency controller uses a high-performance, 64-bit, 2-D graphics accelerator combined with an 8-Mb frame buffer to deliver rapid video graphics processing. It has a –40°C to 85°C operating temperature and a single 5-V power requirement.

The eVAC2000 is supported by a comprehensive software development kit (SDK) for Windows, Linux and QNX that provides a high level API to configure and control the embedded video hardware (via more than 500 internal registers). The SDK includes support libraries and drivers and a range of example applications (including source code).

Contact Advanced Micro Peripherals for pricing.

Advanced Micro Peripherals, Ltd.


Issue 272: EQ Answers

The answers to the Circuit Cellar 272 Engineering Quotient are now available. The problems and answers are listed below.

Problem 1—Why does the power dissipation of a Darlington transistor tend to be higher than that of a single bipolar transistor in switching applications?

Answer 1—In switching applications, a single transistor can saturate, resulting in a low VCE of 0.3 to 0.4 V. However, in a Darlington pair, the output transistor is prevented from saturating by the negative feedback provided by the driver transistor. If the collector voltage drops below the sum of the VBE of the output transistor (about 0.7 V) and the VCE(sat) of the driver transistor (about 0.3 V), the drive current to the output transistor is reduced, preventing it from going into saturation itself. Therefore, the effective VCE(sat) of the Darlington pair is 1 V or more, resulting in much higher dissipation at a given current level.

Problem 2—Suppose you have some 3-bit data, say, grayscale values for which 000 = black and 111 = white. You have a display device that takes 8-bit data, and you want to extend the bit width of your data to match.

If you just pad the data with zeros, you get the value 11100000 for white, which is not full white for the 8-bit display—that would be 11111111. What can you do?

Answer 2—One clever trick is to repeat the bits you have as many times as necessary to fill the output field width. For example, if the 3-bit input value is ABC, the output value would be ABCABCAB. This produces the following mapping, which interpolates nicely between full black and full white (see Table 1). Note that this mapping preserves the original bits; if you want to go back to the 3-bit representation, just take the MSBs and you have the original data.

3-bit INPUT 8-bit OUTPUT
000 00000000
001 00100100
010 01001001
011 01101101
100 10010010
101 10110110
110 11011011
111 11111111

Problem 3—Can an induction motor (e.g., squirrel-cage type) be used as a generator?

Answer 3—Believe it or not, yes it can.

An induction motor has no electrical connections to the rotor; instead, a magnetic field is induced into the rotor by the stator. The motor runs slightly slower than “synchronous” speed—typically 1725 or 3450 rpm when on 60 Hz power.

If the motor is provided with a capacitive load, is driven at slightly higher than synchronous speed (1875 or 3750 rpm), and has enough residual magnetism in the rotor to get itself going, it will generate power up to approximately its rating as a motor. The reactive current of the load capacitor keeps the rotor energized in much the same way as when it is operating as a motor.

See for additional details.

Problem 4—In Figure 1, why does this reconstruction of a 20-kHz sinewave sampled at 44.1 kHz show ripple in its amplitude?

Answer 4—The actual sampled data, represented by the square dots in the diagram, contains equal levels of Fsignal (the sine wave) and Fsample-Fsignal (one of the aliases of the sinewave). Any reconstruction filter is going to have difficulty passing the one and eliminating the other, so you inevitably get some of the alias signal, which, when added to the desired signal, produces the “modulation” you see.

In the case of a software display of a waveform on a computer screen (e.g., such as you might see in software used to edit audio recordings), they’re probably using an FIR low-pass filter (sin(x)/x coefficients) windowed to some finite length. A shorter window gives faster drawing times, so they’re making a tradeoff between visual fidelity and interactive performance. The windowing makes the filter somewhat less than brick-wall, so you get the leakage of the alias and the modulation.

In the case of a real audio D/A converter, even with oversampling you can’t get perfect stopband attenuation (and you must always do at least some of the filtering in the analog domain), so once again you see the leakage and modulation.

In this example, Fsignal = 0.9×Fnyquist, so Falias = 1.1×Fnyquist and Falias/Fsignal = 1.22. To eliminate the visible artifacts, the reconstruction filter would need to have a slope of about 60dB over this frequency span, or about 200 dB/octave.

Electrical Engineer Crossword (Issue 272)

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


1.     JACOBSLADDER—Climbing arc [two words]

5.     WOZNIAK—Apple I

8.     SPARKCOIL—Uses a low-voltage DC supply to create high-voltage pulses

10.   JITTER—Creates an imperfect timing signal

11.   ERG—Energy measurement

13.   ACOUSTICOHM—Equivalent to µbar s/cm3 [two words]

15.   BUFFER—Provides electrical isolation

16.   WIFI—Provides movement to smartphones, PCs, and tablets

17.   POSIX—An IEEE operating system compatibility standard

18.   PEAKTOPEAK—Alterations between high and low values

19.   MUTEX—Capable of ensuring atomic access to any shared resource

20.   NAKAMURA—University of California, Santa Barbara professor credited with inventing the blue LED



2.     OSCILLATOR—American physicist George W. Pierce (1872–1956); piezoelectric

3.     EIGENTONE—A pitch capable of resonance

4.     FRETSONFIRE—Open-source gameplay for music lovers [three words]

6.     NEGATIVEFEEDBACK—Type of amplifier invented in 1927 by Harold Black [two words]

7.     BAFFLE—Sound wave obstruction

9.     MORSECODE—A pre-texting means of communication [two words]

12.   COMBFILTER—Capable of causing delay [two words]

14.   CHIPSET—Intel created the first family of these

Client Profile: Parallax, Inc.

Parallax P8X32A Propeller chips

Parallax, Inc.
599 Menlo Drive
Rocklin, CA 95765

Contact: Emily Kurze

Embedded Products/Services: Parallax P8X32A Propeller chip (Part #P8X32A-Q44), Propeller family. The P8X32A Propeller chip is Parallax’s 8-core, 32-bit, 80-MHz microcontroller. P8X32A Quickstart (Part #40000), Quickstart family. The P8X32A Quickstart board, featuring the Propeller chip, is everything you need to begin designing Propeller-based applications.

Product Information: The P8X32A Propeller chip is a modern, easy-to-use and a powerful multicore microcontroller that has the flexibility to propel your design to the next tier of performance and reliability. With eight independent cores at your disposal, developers can easily instantiate any number of custom soft-peripherals from Parallax’s Object Exchange library to enable the chip to fill nearly any role. From generating graphics for a control system’s VGA display to managing fly-by-wire avionics equipment, the 80-MHz Propeller chip makes short work of embedded applications that require real-time execution.

Parallax Propeller QuickStart Board #40000

Engineer’s “Harlem Shake” Meme

In an blog posted today on the Phoenix New Times site, Troy Farah asks: “Harlem Shake vs. Gallon Smashing Prank: Which Meme Will Destroy America First?” Well, both have caused a lot of problems for smashers and shakers in the United States. We read a recent report about the possible legal issues facing some gallon smashers. And posted a story on March 1 about the FAA’s probe into a recent “shake” on a plane. With negative results such as these, it’s clear that the Smash and the Shake are bidding for the most tile of “most destructive.”

Where does the engineering community stand on these pranks? Well, we have not seen an electrical engineer, robot, or microcontroller-based system smashing a gallon of milk to get a laugh. (Thankfully! We don’t endorse it.) But we did recently seen an engineer’s take on the Harlem Shake.

And so the meme continues.

Be sure to check out Dave Jones’s EEVblog video about the rocker.

RS Components + Elektor = DesignSpark Magazine

RS Components has announced the launch of its new online publication, DesignSpark Magazine. The new magazine will be published in collaboration with Elektor International Media, the global electronics design and publishing house that publishes Elektor, Circuit Cellar, audioXpress, and more.

DesignSpark Magazine will replace RS Components’s popular eTech Magazine, which was first released as a digital edition in July 2010. According to a statement released by RS Components, “The new title is available as a fully digital publication in iPad, iPhone, Android tablet and page-turner formats. The publishing partnership with Elektor will produce not only a fresh-look magazine, but in addition will draw on Elektor’s long experience in the electronics publishing field to deliver the highest quality of technical content as a source of inspiration for design engineers worldwide.”

DesignSpark Magazine, which derives its name from, the RS online community for electronics design engineers, will address three key topic areas:

  • Technologies – This will feature the best boards and board-level components for engineers and give readers a snapshot of the newest hot products in the market.
  • Software and tools – Keeping readers in touch with the latest resources to save time and money, this area will focus on free tools to support engineers.
  • Projects – Inspired by positive feedback on project-style articles in eTech, this expanded section in the new magazine will feature more design-tips articles contributed by Elektor, as well as make-and-build projects from the DesignSpark community. Readers will have access to the information located in this section to develop their own projects.

The new publication is designed to appeal to readers across the globe, with the concurrent launch of eight different language versions: English; Dutch; French; German; Italian; Japanese; Simplified Chinese and Spanish.

Mark Cundle, Head of Technical Marketing at RS, commented, “The RS online DesignSpark community has become a respected and well-used source of information and tools for electronics engineers over the past few years, so it is a natural progression to align the name of our proprietary online publication with the DesignSpark brand. The magazine is an integral part of our efforts to provide customers with a trusted, reliable source of technical information to help reduce design times and costs.”

Wisse Hettinga, International Director for Elektor International Media, said, “This exciting collaboration with RS Components will be good news for everyone who is an enthusiast and active in electronics design. It will mean more designs, more inspiration, more ‘how to’ and ‘where to get’ information to speed up the design process and create new, interesting electronic products.”

[Via] is an Elektor International Media website.

CC272: Issue of Ingenuity

The March issue of Circuit Cellar includes articles from a number of practical problem solvers, such as a homeowner who wanted to get a better grasp of his electrical usage and a professor who built a better-than-average music box.

Dean Boman, a retired spacecraft communications systems designer, decided to add oversight of his electric usage (in real time) to his home-monitoring system. After all, his system already addressed everything from security to fire detection to irrigation control. On page 34, he describes his energy monitoring system, which provides a webpage with circuit-by-circuit energy usage. This level of detail can make you a well-informed energy consumer.

Dean Bowman’s energy-monitoring system

Bruce Land, a senior lecturer in electronics and computer science at Cornell University, thought developing a microcontroller-based music device would be a useful class lesson. But more importantly, he knew his 3-year-old granddaughter would love an interactive music box. On page 28, he shares how he built a music device with an 8-bit microcontroller that enables changing the note sequence, timbre, tempo, and beat.

Computer engineer Chris Paiano has written many application notes for the Cypress programmable-system-on-chip (PSoC) chipset. He is even working on a PSoC solution for his broken dishwasher. But that’s far from his most impressive work. Read an interview with this problem-solver on page 41.

College students built a rotational inverted pendulum (RIP) to test nonlinear control theory. But you might want to make and tune one for fun. Nelson Epp did. On page 20, he describes how he built his RIP and utilized a TV remote control to meet the challenges of balance and swing. “It is a good project because the hardware used is fairly common, the firmware techniques and math behind them are relatively easy to understand, and you get a good feeling when, for the first time, the thing actually works,” he says.

Nelson Epp’s rotational inverted pendulum (RIP)

Chip biometrics are unique digital chip features—left by the manufacturing process—that distinguish one chip from another of the same type. Finding these chip “fingerprints” is important in developing trustworthy and secure electronics. On page 45, Patrick Schaumont discusses how to extract a fingerprint from a field programmable gate array (FPGA) and authenticate a chip’s identity.

Maurizio Di Paolo Emilio, a telecommunications engineer from Italy, designs data acquisition system software for physics experiments and industrial use. In the Tech the Future essay on page 80, he discusses the many alternatives for data acquisition software and the goal of developing credit-card-sized embedded data acquisition systems, using open-source software, to manage industrial systems.

Other article highlights include George Novacek’s look at ways to reduce product failures in the field (p. 52), Ed Nisley’s take on how to get true analog voltages from the Arduino’s PWM outputs (p. 56), and Jeff Bachiochi’s guidance on using a development kit to design a tool to help transmit Morse code (p. 68).

With this issue’s emphasis on robotics, you’ll want to check out  our From the Archives article about a SOPHOCLES design for a solar-powered robot that can detect poisonous gas (p. 62).