Form vs. Function in Test

Input Voltage

–Jeff Child, Editor-in-Chief

JeffHeadShot

A couple months back I and the Circuit Cellar team attended ESC (Embedded Systems Conference) Boston. Having a booth was new for Circuit Cellar at ESC, so we were very pleased at the positive feedback from people who stopped by our booth—a mix of devoted long-time readers and new faces just learning about us. My thanks to those who became new subscribers on the spot. There are many good reasons for a technology editor like myself to attend tradeshows in our industry. Meeting with technology vendors—the people—face to face is the big one. I don’t care how convenient, realistic or powerful our various forms of electronic communication become. There will never—never ever—be any substitute for meetings done in person and the kind of conversation you can have face to face.

Another good reason to attend a show like ESC is to see the “stuff”—the embedded boards, chips, instruments and so on. I can write all day about the size, weight and power of a COM Express board. But it’s kinda nice to feel the size and weight by holding one in my hand. One type of gear that’s enormously important to see close up is test instrumentation products—oscilloscopes, logic analyzers, signal generators and so forth. Fortunately for me, ESC Boston had a nice cluster this year of test equipment exhibitors. Among these were Pico Technology, Rohde & Schwarz, Siglent Technologies, Tektronix and Teledyne LeCroy.

Like many of you, as an Electrical Engineering major in college I had a lot of EE labs. And I have to make a confession: Operating test equipment was never my strong suit. I remember my lab partners would seldom let me touch the oscilloscope once they caught on to my poor skills. I vividly remember a pair of them saying “Let’s have Jeff write the lab report. That’s at least something he’s good at.” Fast forward to my early years as a New Products Editor, and I sat through many press tour meetings. In those days, test equipment companies would make great efforts to lug their gear across country just to set it up and show me every last new feature of their new logic analyzer or scope.

At this year’s ESC Boston, it was fun seeing the state of the art test equipment on display. And I was able to glean a few insights. At today’s state of electronics technology, it’s quite feasible to have an all-in-one test system. But according to the vendors I talked to, there’s still a desire have a stand-alone box one can call an oscilloscope, for example. Also, even though touch-screen and push-button digital interfaces are mature technologies, many test customers still like feel of turning knobs when it comes to operating test gear.

Exemplifying what can be done with today’s technology, Pico Technology’s approach to test gear is to create compact, easily portable box-level systems. Instead of having a screen and arrays of controls, Pico Technology’s test systems instead interface with your laptop, so that laptop provides all the display and control needs for the equipment. Its latest example along those lines is its PicoScope 9300 Series of sampling oscilloscopes designed for measuring high-speed signals. The 9300 Series scopes provide 2 channels, 15 GHz bandwidth and 15 Terasample/s (64 fs) sequential sampling.

Rohde & Schwarz in contrast makes more traditional test gear, focusing on the high-performance end of the market. Its latest offering is its enhanced power-of-ten oscilloscope family with 10-bit resolution and large memory depth. According to the company, the power-of-ten oscilloscope families R&S RTB2000, R&S RTM3000 and R&S RTA4000 provide 10 times as much memory as comparable instruments and large 10.1” touchscreen displays.

Among the new products on display at Teledyne LeCroy’s booth at ESC Boston was what it claims as the industry’s first HDMI 2.1 Fixed Rate Link (FRL) Video Generator. FRL is the transport mode for HDMI 2.1 which enables transmission of uncompressed 8K video formats to reach link rates of up to 48 Gb/s.

All in all, my two days at ESC Boston were well spent. Aside from those test equipment vendors, there were a great mix of embedded hardware and embedded software tool vendors I met with at the show. I also sat in on a few presentations, including a great one called “ARM Trace: Kills Bugs Fast!” by IAR Systems’ Shawn Prestridge

This appears in the June (335) issue of Circuit Cellar magazine

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A Serene Workspace for Board Evaluation and Writing

 Elecronics engineer, entrepreneur, and author Jack Ganssle recently sent us information about his Finksburg, MD, workspace:

I’m in a very rural area and I value the quietness and the view out of the window over my desk. However, there are more farmers than engineers here so there’s not much of a high-tech community! I work out of the house and share an office with my wife, who handles all of my travel and administrative matters. My corner is both lab space and desk. Some of the equipment changes fairly rapidly as vendors send in gear for reviews and evaluation.

ganssle-workspace

Ganssle’s desk is home to ever-changing equipment. His Agilent Technologies MSO-X-3054A mixed-signal oscilloscope is a mainstay.

The centerpiece, though, is my Agilent Technologies MSO-X-3054A mixed-signal oscilloscope. It’s 500 MHz, 4 GSps, and includes four analog channels and 16 digital channels, as well as a waveform generator and protocol analyzer. I capture a lot of oscilloscope traces for articles and talks, and the USB interface sure makes that easy. That’s pretty common on oscilloscopes, now, but being an old-timer I remember struggling with a Polaroid scope camera.

The oscilloscope’s waveform generator has somewhat slow (20-ns) rise time when making pulses, so the little circuit attached to it sharpens this to 700 ps, which is much more useful for my work. The photo shows a Siglent SDS1102CML oscilloscope on the bench that I’m currently evaluating. It’s amazing how much capability gets packed into these inexpensive instruments.

The place is actually packed with oscilloscopes and logic analyzers, but most are tucked away. I don’t know how many of those little USB oscilloscope/logic analyzers vendors have sent for reviews. I’m partial to bench instruments, but do like the fact that the USB instruments are typically quite cheap. Most have so-so analog performance but the digital sampling is generally great.

Only barely visible in the picture, under the bench there’s an oscilloscope from 1946 with a 2” CRT I got on eBay just for fun. It’s a piece of garbage with a very nonlinear timebase, but a lot of fun. The beam is aimed by moving a magnet around! Including the CRT there are only four tubes. Can you imagine making anything with just four transistors today?

The big signal generator is a Hewlett-Packward 8640B, one of the finest ever made with astonishing spectral purity and a 0.5-dB amplitude flatness across 0.5 MHz to 1 GHz. A couple of digital multimeters and a pair of power supplies are visible as well. The KORAD supply has a USB connection and a serviceable, if klunky, PC application that drives it. Sometimes an experiment needs a slowly changing voltage, which the KORAD manages pretty well.

They’re mostly packed away, but I have a ton of evaluation kits and development boards. A Xilinx MicroZed is shown on the bench. It’s is a very cool board that has a pair of Cortex-A9s plus FPGA fabric in a single chip.

I use IDEs and debuggers from, well, everyone: Microchip Technology, IAR Systems, Keil, Segger, you name it. These run on a variety of processors but, along with so many others, more and more I’m using Cortex-M series parts.

My usual lab work is either evaluating boards, products and instruments, or running experiments that turn into articles. It pains me to see so much engineering is done via superstition today. For example, people pick switch contact debounce times based on hearsay or smoke signals or something. Engineers need data, so I tested about 50 pairs of switches to determine what real bounce characteristics are. The results are on my website. Ditto for watchdog timers and other important issues embedded people deal with.

Ganssle notes that his other “bench” is his woodworking shop. To learn more about Ganssle, read our 2013 interview.