Q&A: Ayse Kivilcim Coskun (Engineer, BU)

Ayse Kivilcim Coskun’s research on 3-D stacked systems has gained notoriety in academia, and it could change the way electrical engineers and chip manufacturers think about energy efficiency for years to come. In a recent interview, the Boston University engineering professor briefed us on her work and explained how she came to focus on the topics of green computing and 3-D systems.

Boston University professor Ayse Kivilcim Coskun

The following is an excerpt from an interview that appears in Circuit Cellar 264 (July 2012), which is currently on newsstands.

NAN: When did you first become interested in computer engineering?

AYSE: I’ve been interested in electronics since high school and in science and physics since I was little. My undergraduate major was microelectronics engineering. I actually did not start studying computer engineering officially until graduate school at University of California, San Diego. However, during my undergraduate education, I started taking programming, operating systems, logic design, and computer architecture classes, which spiked my interest in the area.

NAN: Tell us about your teaching position at the Electrical and Computer Engineering Department at Boston University (BU).

AYSE: I have been an assistant professor at BU for almost three years. I teach Introduction to Software Engineering to undergraduates and Introduction to Embedded systems to graduate students. I enjoy that both courses develop computational thinking as well as hands-on implementation skills. It’s great to see the students learning to build systems and have fun while learning.

NAN: As an engineering professor, you have some insight into what excites future engineers. What “hot topics” currently interest your students?

AYSE: Programming and software design in general are certainly attracting a lot of interest. Our introductory software engineering class is attracting a growing number of students across the College of Engineering every year. DSP, image processing, and security are also hot topics among the students. Our engineering students are very keen on seeing a working system at the end of their class projects. Some project examples from my embedded systems class include embedded low-power gaming consoles, autonomous toy vehicles, and embedded systems focusing on healthcare or security applications …

NAN: How did you come to focus on energy efficiency and thermal challenges?

AYSE: Energy efficiency has been a hot topic for embedded systems for several decades, mainly due to battery-life restrictions. With the growth of computing sources at all levels—from embedded to large-scale computers, and following the move to data centers and the cloud—now energy efficiency is a major bottleneck for any computing system. The focus on energy efficiency and temperature management among the academic community was increasing when I started my PhD. I got especially interested in thermally induced problems as I also had some background on fault tolerance and reliability topics. I thought it would be interesting to leverage job scheduling to improve thermal behavior and my advisor liked the idea too. Temperature-aware job scheduling in multiprocessor systems was the first energy-efficiency related project I worked on.

NAN: In May 2011, you were awarded the A. Richard Newton Graduate Scholarship at the Design Automation Conference (DAC) for a joint project, “3-D Systems for Low-Power High-Performance Computing.” Tell us about the project and how you became involved.

AYSE: My vision is that 3-D stacked systems—where multiple dies are stacked together into a single chip—can provide significant benefits in energy efficiency. However, there are design, modeling, and management challenges that need to be addressed in order to simultaneously achieve energy efficiency and reliability. For example, stacking enables putting DRAM and processor cores together on a single 3-D chip. This means we can cut down the memory access latency, which is the main performance bottleneck for a lot of applications today. This gain in performance could be leveraged to run processors at a lower speed or use simpler cores, which would enable low-power, high-performance computing. Or we can use the reduction in memory latency to boost performance of single-chip multicore systems. Higher performance, however, means higher power and temperature. Thermal challenges are already pressing concerns for 3-D design, as cooling these systems is difficult. The project focuses on simultaneously analyzing performance, power, and temperature and using this analysis to design system management methods that maximize performance under power or thermal constraints.

I started researching 3-D systems during a summer internship at  the Swiss Federal Institute of Technology (EPFL) in the last year of my PhD. Now, the area is maturing and there are even some 3-D prototype systems being designed. I think it is an exciting time for 3-D research as we’ll start seeing a larger pool of commercial 3-D stacked chips in a few years. The A. Richard Newton scholarship enabled us to do the preliminary research and collect results. Following the scholarship, I also received a National Science Foundation (NSF) CAREER award for designing innovative strategies for modeling and management of 3-D stacked systems.

The entire interview appears in Circuit Cellar 264  (July 2012).

Q&A: Aubrey Kagan (Engineer, Author)

Aubrey Kagan is a talented engineer with years of experience designing embedded systems. He’s also a prolific author. Between 2000 and 2010 he published 15 articles with Circuit Cellar on topics ranging from developing an AC current generator to resilience in embedded designs. His 2004 book Excel By Example: A Microsoft Excel Cookbook for Electronics Engineers provides tips on using Excel for engineering computations, data analysis, circuit modeling, and more.

In Circuit Cellar 263 (June 2012), Kagan opens up in a candid interview with editor Nan Price. Below is an abridged version of an interview that currently appears in Circuit Cellar 263.

AUBREY KAGAN: I live on the northern edge of Toronto, Ontario, Canada. However, that belies my accent, which the readers obviously cannot hear. I was born and grew up in “deepest, darkest Africa” just north of Rudyard Kipling’s “great gray-green, greasy Limpopo River” (see “How the Elephant Got Its Trunk” from Kipling’s Just So Stories) in what is now called Zimbabwe (then Rhodesia). I did my undergraduate engineering degree at the Technion, Israel Institute of Technology, and then returned to Africa for my MBA at the University of the Witwatersrand in South Africa. My early years in engineering were spent in South Africa, immigrating to Canada in 1989.

NAN PRICE: What is your current occupation?

AUBREY: I am an engineering manager at Emphatec, although managing occupies only a small portion of my day—the majority of my time is engineering. Most of the projects are for industrial monitoring and control. They tend to be a blend of analog and digital approaches and usually are quite compact with only a single function.

Engineer and author Aubrey Kagan

NAN: How long have you been interested in designing embedded systems?

AUBREY: I was given the opportunity to get into embedded design long before anybody thought to call it that. It was in 1977, and all we had were microprocessors, which I was trying to design into HF radio transceivers. I had been struggling with phase lock loops and control of the frequency divider seemed a likely candidate for computer control. Just at that time, there was an article in Popular Electronics on creating an evaluation board for the RCA CDP1802 COSMAC microprocessor. I used that as the basis for the development and as they say, the rest is history.

NAN: Circuit Cellar Online featured your article, “Developing an AC Current Generator” (119, 2000). Tell our newer readers about that project. Do you still use the generator? Have you made any upgrades to it?

AUBREY: That was my first Circuit Cellar article and my only collaborative effort (with Ernesto Gradin). It is probably my favorite project because it is so unusual and remains pertinent to this day.

This AC current generator is one of Kagan’s favorite projects.

Some of the products that we make involve monitoring an AC current and converting the measurement to a 4-to-20-mA analog signal. Some of the devices will measure currents up to 100 A AC. In order to test and calibrate these units, obviously you need an accurate current. If you use a variable AC voltage into a fixed load or a fixed voltage into a variable load to generate the current, you will be working with dangerous voltages and lots of heat. This leads to errors due to heating and more importantly health risks to the operators. We all know in transformers (VIN × IIN) = (VOUT × IOUT) and VIN = (N × VOUT) and so if you make a transformer with a low number of output turns, there is a low output voltage, and for a given power input you can then derive a high current—no heat and very low voltage. To improve the performance, we added a feedback loop with a micro then implemented PID control. The generator is still in use. I have not made any upgrades to it, but I certainly could improve upon it now. I would like to increase its resolution, and of course some of the components are now obsolete, so they would need revision. I might consider onboard displays as well, not control from a PC.

NAN: Your 2002 article series, “Driving the NKK SmartSwitch” (Circuit Cellar 144 and 145), focused on using a Cypress Microsystems programm-able system-on-chip (PSoC) microcomputer as an interface to drive the SmartSwitch. Tell us how this project came about.

AUBREY: Signal conditioning modules in the process-control market tend to be physically small, typically 2” high by 3” deep by 0.75” wide. Of course, there are many much bigger and smaller examples. All of them mount on a rail installed in a panel. Aside from some LED indications, there is very little information you can glean by just looking at the modules. As a result, there has been a slow trend in the industry to add displays to each individual module. Because of the size, the displays are small and are limited to seven-segment displays of up to four digits and sometimes some indicators, if a custom LCD has been used. Also, the displays are invisible when the panel door is closed. The NKK SmartSwitch would allow three lines of six alphanumeric characters and even some graphics. It would also allow the user to change operational parameters for the module. The NKK projects through the panel door and so the information is available to the outside world.

Simply driving the display was the focus of my discussion in Circuit Cellar. At the time, the article had the distinction of being used as an application note by two different companies simultaneously (NKK and Cypress).

But there is much more to the story. If an NKK SmartSwitch and driver were added to a single module, it would probably double the effective price of the module, and so we came up with a networked approach that allowed a single NKK SmartSwitch to be shared among up to 30 different modules spreading the costs and now becoming economically more viable.

Circuit Cellar 263 (June 2012) is now available.

EE’s Two-Bench Workspace in Silicon Valley

I met Vincent Himpe—a Senior Staff Engineer at STMicroelectronics—a few years ago at the Emebdded Systems Conference in San Jose, CA. It took all of about 5 minutes to learn that he was an engineer with a lot on his mind. Himpe described his work on hard disk drives, sketched a few circuits on a piece of paper, and even mentioned a few ideas for books. (Yes, that’s books—plural.) Where does such a productive engineer get so many ideas and all that energy? I wondered after we parted. I didn’t get to ask him before the conference ended.

Fortunately, Himpe recently contacted me, so I took the opportunity to get more insight into the life of such a multitalented engineer. I sent him a few questions via email, and he kindly replied. We have some insight into where he does a lot of creating, problem solving, programming, and writing.

When Himpe isn’t working on advanced controller devices for hard disk drives at STMicro, he’s writing books (check out Mastering the I2C Bus, Elektor 2011), tackling personal design projects, and repairing surplus electronic electronic equipment in two-bench workspace in San Jose.

My short interview with Himpe appears after the following two photos of his San Jose-based workspace.

Vincent Himpe’s workbench for hardware development

Himpe’s workbench for programming

C. J.: What are you working these days?

VINCENT: I make the reference designs and the development system for a hard disk mechatronic interface chip. This chip spins the 3 phase motor, does the head positioning including velocity control for the seek algorithms, shock sensing (to park the heads when freefall or shock is detected), provides power to all other parts (it’s got 4 switching regulators onboard). In case of unexpected power loss, we protect the data by retracting the heads. We recycle the mechanical energy in the spinning platters by using the motor as generator. This gives us a few seconds of power where we can gracefully shutdown the drive, preventing disasters.

C. J.: What sorts of projects do you work on at these two workstations? Work-related projects? Personal projects?

VINCENT: Personal projects. I have a number of books published through Elektor. Some of the hardware for those was developed there.

C. J.: Can you tell us a bit about the equipment at your hardware workstation? What do you use most frequently?

VINCENT: This is almost all salvaged equipment that was half functioning or broken. Some machines were repaired by combining two broken ones. I scout local surplus stores and eBay for damaged equipment. And once in a while you get lucky. There was a local company moving to a new building. They had ceased hardware development a couple of years ago and only do IP blocks now. They had a “yard sale.” That’s where I picked up my logic analyzer and my favorite scope: an Agilent mso7104: 4 analog and 16 digital channels 1GHz bandwidth with deep memory and all the protocols enabled.

C. J.: It looks like you’re working on something at the hardware bench. On the shelf is some equipment with red wires.

VINCENT: Those are three bench power supplies e3410 from Agilent. Next to it are three 34401 multimeters, also Agilent. I’m a bit of an Agilent fan. The fact that you can easily get full-service manuals that include schematics, calibration and troubleshooting procedures makes it ideal to fix these machines. That’s not the case with many other brands. Plus, they are built to last.

C. J.: What’s the piece of equipment directly under the magnifier/lamp?

VINCENT: Looks like a roll of desoldering wick. I was working on the ringlight. You can see a circular PCB just above it. Thirty-six white LEDs driven by a current-controlled boost pump with PWM. The halogen light bulbs in my Mantis burn out too easily. So I will replace them with this ringlight.

C. J.: How many solder stations do you have at your hardware station?

VINCENT: About seven. I have a Microtouch for precision work, SMD tweezers to remove passives, a hot air pencil, two WSP80s with different tips (so I don’t have to switch tip continuously while working), and a regular desoldering station with a vacuum pump. These are all surplus and/or repaired machines.

C. J.: What is board you’re working with at your software station?

VINCENT: That is a controller board for a UV exposure unit to make PCBs. It’s got an ATmega328 and LCD display. The board does double duty as pizza oven reflow controller. Just install two thermocouple interface chips and change software.

CircuitCellar.com is an Elektor International Media (EIM) publication. EIM published Himpe’s book, Mastering the I2C Bus.

Q&A: Dave Jones (Engineer, EEVBlog)

Are you an electrical engineer, hacker, or maker looking for a steady dose of reliable product reviews, technical insight, and EE musings? If so, Dave Jones is your man. The Sydney, Australia-based engineer’s video blog (EEVblog) and podcast (The Amp Hour, which he co-hosts with Chris Gammell) are quickly becoming must-subscribe feeds for plugged-in inquisitive electronics enthusiasts around the world.

Dave Jones: engineer, video blogger, and podcaster

The April issue of Circuit Cellar features an interview with Jones, who describes his passion for electronics, reviewing various technologies, and his unscripted approach to video blogging and podcasting. Below is an abridged version of the interview.

David L. Jones is a risk taker. In addition to jumping off cliffs in the name of product testing, the long-time engineer recently switched to full-time blogging. In February 2012, Dave and I discussed his passion for electronics, his product review process, and what it means to be a full-time video blogger.—Nan Price, Associate Editor

NAN: When did you first start working with electronics?

DAVE: The video story can be found at “EEVblog #54 – Electronics – When I was a boy…” www.youtube.com/watch?v=XpayYlJdbJk. I was very young, maybe six or so, when I was taking apart stuff to see how it worked, so my parents got me a 50-in-1Tandy (RadioShack) electronics kit and that was it, I was hooked, electronics became my life. And indeed, this seems to be fairly typical of how many engineers of the era got started.

By the time I was eight, I already had my own lab and was working on my own projects. All my pocket money went into tools, parts, and magazines.

The electronics magazine industry was everything back then before the Internet and communications revolution. I would eagerly await every issue of the Australian electronics magazines like Electronics Australia, Electronics Today International (ETI), Applied and Australian Electronics Monthly (AEM), Talking Electronics, and later Silicon Chip.

NAN: Tell us about some of your early projects.

DAVE: Given that it was over 30 years ago, it’s hard to recall I’m afraid. Unfortunately, I just didn’t think to use a (film) camera back then to record stuff, it just wasn’t something that you did as a kid. The family camera only came out on special occasions. So those projects have been lost in the annals of time.

My first big published magazine project was a digital storage oscilloscope (DSO) adapter for PCs, in a 1993 issue of Electronics Australia. I originally designed this in the late 1980s. (See “electronics.alternatezone.com, http://alternatezone.com/electronics/dsoa.ht.)

NAN: You have many interests and talents. What made you choose engineering as your full-time gig?

DAVE: There was no choice, electronics has been my main hobby since I can remember, so electronics engineering was all I ever wanted to do to. I’ve branched out into a few other hobbies over the years, but electronics has always remained what I’ve wanted to do.

NAN: The Electronics Engineering Video Blog—EEVBlog—is touted as “an off-the-cuff video blog for electronics engineers, hobbyists, hackers, and makers.” Tell us about EEVBlog and what inspired you to begin it.

DAVE: I’ve always been into sharing my electronics, either through magazines, via my website, or on newsgroups, so I guess it’s natural that I’d end up doing something like this.

In early 2009 I saw that (WordPress-type) blogs were really taking off for all sorts of topics and some people were even doing “video blogs” on YouTube. I wondered if there were any blogs for electronics, and after a search I found a lot of text-based blogs, but it seemed like no one was doing a video blog about electronics, like a weekly show that people could watch … So I thought it’d be fun to do an electronics video blog and blaze a new trail and see what happened.

Being fairly impulsive, I didn’t think about it much; I just dusted off a horrible old 320 × 240 webcam, sat down in front of my computer, and recorded 10 minutes (the YouTube limit back then) of whatever came into my head. I figured a product review, a book review, a chip review, and some industry news was a good mix … I’ve had constant linear growth since then, and now have a regular weekly audience of over 10,000 viewers and over 4 million views on YouTube. Not to mention that it’s now my full-time job.

The complete April issue of Circuit Cellar is now available. For more information about Dave Jones, his video blog, and podcast, visit www.eevblog.com and www.theamphour.com.

Q&A: Per Lundahl (Transformer Design)

Per Lundahl is a multitalented designer who runs one of world’s leading high-performance audio transformer manufacturing outfits, Lundahl Transformers, which is based in Norrtalje, Sweden. After graduating from the School of Physics at the Royal Institute of Technology in Stockholm, he worked as a computer consultant for Ericsson. It wasn’t until he decided to move out of the city that he joined his family’s business, which his parents started in 1958.

Per Lundahl, CEO of Lundahl Transformers

In the April 2012 issue of audioXpress magazine, Lundahl shares stories about the company’s focus and products. He states:

I design all our new transformers. Our audio market is divided into two segments, Pro Audio and Audiophile. The Pro Audio segment includes transformers for microphones, mic pre-amps, splitters, distribution amplifiers, and other studio equipment. The Audiophile segment is transformers for MC phono cartridge step-up and for tube and solid state amplifiers.

Our biggest selling products are two types of transformers for microphone preamplifier inputs. In the Audiophile domain, our tube amplifier interstage and line output transformers are popular.

We constantly develop new transformers based on the requests of our customers. Presently we are developing an auto-transformer for a Chinese company and an interstage/line output transformer for some European customers. The latter will probably be added to our range of standard transformers, available to everyone.

For the very fastidious audiophile, we are also introducing silver wire in some of our transformer types. Initially, the wire will mainly be in our high-end MC transformers, but depending on the response, it is possible that we will extend the silver wire product range.

You can read the entire interview in audioXpressApril, which is currently available on newsstands.

Tube amp transformers

audioXpress is an Elektor group publication.