CC268: The History of Embedded Tech

At the end of September 2012, an enthusiastic crew of electrical engineers and journalists (and significant others) traveled to Portsmouth, NH, from locations as far apart as San Luis Obispo, CA,  and Paris, France, to celebrate Circuit Cellar’s 25th anniversary. Attendees included Don Akkermans (Director, Elektor International Media), Steve Ciarcia (Founder, Circuit Cellar), the current magazine staff, and several well-known engineers, editors, and columnists. The event marked the beginning of the next chapter in the history of this long-revered publication. As you’d expect, contributors and staffers both reminisced about the past and shared ideas about its future. And in many instances, the conversations turned to the content in this issue, which was at that time entering the final phase of production. Why? We purposely designed this issue (and next month’s) to feature a diversity of content that would represent the breadth of coverage we’ve come to deliver during the past quarter century. A quick look at this issue’s topics gives you an idea of how far embedded technology has come. The topics also point to the fact that some of the most popular ’80s-era engineering concerns are as relevant as ever. Let’s review.

In the earliest issues of Circuit Cellar, home control was one of the hottest topics. Today, inventive DIY home control projects are highly coveted by professional engineers and newbies alike. On page 16, Scott Weber presents an interesting GPS-based time server for lighting control applications. An MCU extracts time from GPS data and transmits it to networked devices.

The time-broadcasting device includes a circuit board that’s attached to a GPS module. (Source: S. Weber, CC268)

Thiadmer Riemersma’s DIY automated component dispenser is a contemporary solution to a problem that has frustrated engineers for decades (p. 26). The MCU-based design simplifies component management and will be a welcome addition to any workbench.

The DIY automated component dispenser. (Source: T. Riemersma, CC268)

USB technology started becoming relevant in the mid-to-late 1990s, and since then has become the go-to connection option for designers and end users alike. Turn to page 30 for Jan Axelson’s  tips about debugging USB firmware. Axelson covers controller architectures and details devices such as the FTDI FT232R USB UART controller and Microchip Technology’s PIC18F4550 microcontroller.

Debugging USB firmware (Source: J. Axelson, CC268)

Electrical engineers have been trying to “control time” in various ways since the earliest innovators began studying and experimenting with electric charge. Contemporary timing control systems are implemented in a amazing ways. For instance, Richard Lord built a digital camera controller that enables him to photograph the movement of high-speed objects (p. 36).

Security and product reliability are topics that have been on the minds of engineers for decades. Whether you’re working on aerospace electronics or a compact embedded system for your workbench (p. 52), you’ll want to ensure your data is protected and that you’ve gone through the necessary steps to predict your project’s likely reliability (p. 60).

The issue’s last two articles detail how to use contemporary electronics to improve older mechanical systems. On page 64 George Martin presents a tachometer design you can implement immediately in a machine shop. And lastly, on page 70, Jeff Bachiochi wraps up his series “Mechanical Gyroscope Replacement.” The goal is to transmit reliable data to motor controllers. The photo below shows the Pololu MinIMU-9.

The Pololu MinIMU-9′s sensor axes are aligned with the mechanical gyro so the x and y output pitch and roll, respectively. (Source: J. Bachiochi, CC268)

Great Plains Super Launch

Contributed by Mark Conner

The Great Plains Super Launch (GPSL) is an annual gathering of Amateur Radio high-altitude ballooning enthusiasts from the United States and Canada. The 2012 event was held in Omaha, Nebraska from June 7th to the 9th and was sponsored by Circuit Cellar and Elektor. Around 40 people from nine states and the Canadian province of Saskatchewan attended Friday’s conference and around 60 attended the balloon launches on Saturday.

Amateur Radio high-altitude ballooning (ARHAB) involves the launching, tracking, and recovery of balloon-borne scientific and electronic equipment. The Amateur Radio portion of ARHAB is used for transmitting and receiving location and other data from the balloon to chase teams on the ground. The balloon is usually a large latex weather balloon, though other types such as polyethylene can also be used. A GPS unit in the balloon payload calculates the location, course, speed, and altitude in real time, while other electronics, usually custom-built, handle conversion of the digital data into radio signals. These signals are then converted back to data by the chase teams’ receivers and computers. The balloon rises at about 1000 feet per minute until the balloon pops (if it’s latex) or a device releases the lifting gas (if it’s PE). Maximum altitudes are around 100,000 feet and the flight typically takes two to three hours.

Prepping for the launch – Photo courtesy of Mark Conner

On Thursday the 7th, the GPSL attendees visited the Strategic Air and Space Museum near Ashland, about 20 minutes southwest of Omaha. The museum features a large number of Cold War aircraft housed in two huge hangars, along with artifacts, interactive exhibits, and special events. The premiere aircraft exhibit is the Lockheed SR-71 Blackbird suspended from the ceiling in the museum’s atrium. A guided tour was provided by one of the museum’s volunteers and greatly enjoyed by all.

Friday featured the conference portion of the Super Launch. Presentations were given on stabilization techniques for in-flight video recordings, use of ballooning projects in education research, lightweight transmitters for tracking the balloon’s flight, and compressed gas safety. Bill Brown showed highlights from his years of involvement in ARHAB dating back to his first flights in 1987. The Edge of Space Sciences team presented on a May launch from Coors Field in Denver for “Weather and Science Day” prior to an afternoon Colorado Rockies game. Several thousand students witnessed the launch, which required meticulous planning and preparation.

EOSS ready for launch – Photo courtesy of Mark Conner

Saturday featured the launch of five balloons from a nearby high school early that morning. While the winds became gusty for the last two launches, all of the flights were successfully released into a brilliant sunny June sky. All five of the flights were recovered without damage in the corn and soybean fields of western Iowa between 10 and 25 miles from launch. The SABRE team from Saskatoon, Saskatchewan took the high flight award, reaching over 111,000 ft during their three-hour flight.

The view from one of the balloons. Image credit: “Project Traveler / Zack Clobes”.

The 2013 GPSL will be held in Pella, Iowa, on June 13-15. Watch the website for additional information as the date approaches.

RFI Bypasssing

With GPS technology and audio radio interfaces on his personal fleet of bikes, Circuit Cellar columnist Ed Nisley’s family can communicate to each other while sending GPS location data via an automatic packet reporting system (APRS) network. In his February 2012 article, Ed describes a project for which he used a KG-UV3D radio interface rigged with SMD capacitors to suppress RF energy. He covers topics such as test-fixture measurements on isolated capacitors and bypassing beyond VHF.

Photo 2 from the Febuary article, "RFI Bypassing (Part 1)." A pair of axial-lead resistors isolate the tracking generator and spectrum analyzer from the components under test. The 47-Ω SMD resistor, standing upright just to the right of the resistor lead junction, forms an almost perfect terminator. (Source: Ed Nisley CC259)

Ed writes:

Repeatable and dependable measurements require a solid test fixture. Although the collection of parts in Photo 2 may look like a kludge, it’s an exemplar of the “ugly construction” technique that’s actually a good way to build RF circuits. “Some Thoughts on Breadboarding,” by Wes Hayword, W7ZOI, gives details and suggestions for constructing RF projects above a solid printed circuit board (PCB) ground plane.

You can read this article now in Circuit Cellar 259. If you aren’t a subscriber, you can purchase a copy of the issue here.


GPS-Based Vehicle Timing & Tracking Project

The KartTracker’s Renesas kit (Source: Steve Lubbers CC259)

You can design and construct your own vehicle timing system at your workbench. Steve Lubbers did just that, and he describes his project in Circuit Cellar 259 (February 2012). He calls his design the “Kart Tracker,” which he built around a Renesas Electronics Corp. RX62N RDK. In fact, Steve writes that the kit has most of what’s need to bring such a design to fruition:

Most of the pieces of my KartTracker are already built into the Renesas Electronics RX62N development board (see Figure 1). The liquid crystal display (LCD) on the development board operates as the user interface and shows the driver what is happening as he races. The integrated accelerometer can be used to record the G forces experienced while racing. A serial port provides connections to a GPS receiver and a wireless transmitter. Removable flash memory stores all the race data so you can brag to your friends. You now have all of the pieces of my KartTracker.

The following block diagram depicts the relationship between the CPU, base station, flash drive, and other key components:

KartTracker Diagram (Source: Steve Lubbers CC259)

The software for the system is fairly straightforward. Steve writes:

The KartTracker software was built around the UART software sample provided with the RX62N development kit. To provide file system support, the Renesas microSD/Tiny FAT software was added. Finally, my custom GPS KartTracker software was added to the Renesas samples. My software consists of GPS, navigation, waypoints, and display modules. Support software was added to interface to the UART serial port, the file system, and the user display and control on the RX62N circuit board.

Pseudocode for the main processing loop (Source: Steve Lubbers CC259)

Read Steve’s article in the February issue for more details.

If you want to build a similar system, you should get familiar with the Renesas RX62N RDK. In the following video, Dave Jones of EEVBlog provides a quick and useful introduction to the RX62N RDK and its specs (Source: Renesas).

Good luck with this project. Be sure to keep Circuit Cellar posted on your progress!

Click here to purchase Circuit Cellar 259.