Wireless Data Links (Part 2): Transmitters and Antennas

If you built your own ham radio “back in the day,” you’ll recall the frustration of putting it together with components that were basic at best.

But as columnist George Novacek points out in the second installment of his series examining wireless data links: “Today you can purchase excellent, reasonably priced low-power gear for data communications off the shelf.”

Transmitter and receiver

Photo 1: SparkFun Electronics’s WRL-10524 transmitter and WRL-10532 receiver are low cost, basic, and work well.

Part 2 of Novacek’s series, appearing in the March issue, looks at transmitters and antennas.

In one section, Novacek expands upon the five basic data-transmitter modules—a data encoder, a modulator, a carrier frequency generator, an RF output amplifier, and an antenna:

Low-power data transmitters often integrate the modulator, the carrier frequency generator, and the amplifier into one circuit. A single transistor can do the job. I’ll discuss antennas later. When a transmitter and a receiver are combined into one unit, it’s called a transceiver.

Modulation may not be needed in some simple applications where the mere presence of a carrier is detected to initiate an action. A simple push button will suffice, but this is rarely used as it is subject to false triggering by other transmitters working in the area in the same frequency band.

Digital encoder and decoder ICs are available for simple devices (e.g., garage door openers) or keyless entry where just an on or off output is required from the receiver. These ICs generate a data packet for transmission. If the received packet matches the data stored in the decoder, an action is initiated. Typical examples include Holtek Semiconductor HT12E encoders and HT12D decoders and Freescale Semiconductor MC145026, MC145027, and MC145028 encoder and decoder pairs. For data communications a similar but more advanced scheme is used. I’ll address this when I discuss receivers (coming up in Part 3 of this series).

Novacek’s column goes on to explain modulation types, including OOK and ASK modulation:

OOK modulation is achieved by feeding the Data In line with a 0-to+V-level  datastream. ASK modulation can be achieved by the data varying the transistor biasing to swing the RF output between 100% and typically 30% to 50% amplitude. I prefer to add a separate modulator.

The advantage of ASK as opposed to OOK modulation is that the carrier is always present, thus the receiver is not required to repeatedly synchronize to it. Different manufacturers’ specifications claim substantially higher achievable data rates with ASK rather than OOK.

For instance, Photo 1 shows a SparkFun Electronics WRL-10534 transmitter and a WRL-10532 receiver set for 433.9 MHz (a 315-MHz set is also available), which costs less than $10. It is a bare-bones design, but it works well. When you build supporting circuits around it you can get excellent results. The set is a good starting point for experimentation.

The article also includes tips on a transceiver you can purchase to save time in developing ancillary circuits (XBee), while noting a variety of transceiver, receiver, and transmitter modules are available from manufacturers such as Maxim Integrated, Micrel, and RF Monolithics (RFM).  In addition, the article discusses design and optimization of the three forms of antennas: a straight conductor (monopole), a coil (helical), and a loop.

“These can be external, internal, or even etched onto the PCB (e.g., keyless entry fobs) to minimize the size,” Novacek says.

Do you need advice on what to consider when choosing an antenna for your design?  Find these tips and more in Novacek’s March issue article.

The Future of Small Radar Technology

Directing the limited resources of Fighter Command to intercept a fleet of Luftwaffe bombers en route to London or accurately engaging the Imperial Navy at 18,000 yards in the dead of night. This was our grandfather’s radar, the technology that evened the odds in World War II.

This is the combat information center aboard a World War II destroyer with two radar displays.

This is the combat information center aboard a World War II destroyer with two radar displays.

Today there is an insatiable demand for short-range sensors (i.e., small radar technology)—from autonomous vehicles to gaming consoles and consumer devices. State-of-the-art sensors that can provide full 3-D mapping of a small-target scenes include laser radar and time-of-flight (ToF) cameras. Less expensive and less accurate acoustic and infrared devices sense proximity and coarse angle of arrival. The one sensor often overlooked by the both the DIY and professional designer is radar.

However, some are beginning to apply small radar technology to solve the world’s problems. Here are specific examples:

Autonomous vehicles: In 2007, the General Motors and Carnegie Mellon University Tartan Racing team won the Defense Advanced Research Projects Agency (DARPA) Urban Challenge, where autonomous vehicles had to drive through a city in the shortest possible time period. Numerous small radar devices aided in their real-time decision making. Small radar devices will be a key enabling technology for autonomous vehicles—from self-driving automobiles to unmanned aerial drones.

Consumer products: Recently, Massachusetts Institute of Technology (MIT) researchers developed a radar sensor for gaming systems, shown to be capable of detecting gestures and other complex movements inside a room and through interior walls. Expect small radar devices to play a key role in enabling user interface on gaming consoles to smartphones.

The Internet of Things (IoT): Fybr is a technology company that uses small radar sensors to detect the presence of parked automobiles, creating the most accurate parking detection system in the world for smart cities to manage parking and traffic congestion in real time. Small radar sensors will enable the IoT by providing accurate intelligence to data aggregators.

Automotive: Small radar devices are found in mid- to high-priced automobiles in automated cruise control, blind-spot detection, and parking aids. Small radar devices will soon play a key role in automatic braking, obstacle-avoidance systems, and eventually self-driving automobiles, greatly increasing passenger safety.

Through-Wall Imaging: Advances in small radar have numerous possible military applications, including recent MIT work on through-wall imaging of human targets through solid concrete walls. Expect more military uses of small radar technology.

What is taking so long? A tremendous knowledge gap exists between writing the application and emitting, then detecting, scattered microwave fields and understanding the result. Radar was originally developed by physicists who had a deep understanding of electromagnetics and were interested in the theory of microwave propagation and scattering. They created everything from scratch, from antennas to specialized vacuum tubes.

Microwave tube development, for example, required a working knowledge of particle physics. Due to this legacy, radar textbooks are often intensely theoretical. Furthermore, microwave components were very expensive—handmade and gold-plated. Radar was primarily developed by governments and the military, which made high-dollar investments for national security.

Small radar devices such as the RFBeam Microwave K-LC1a radio transceiver cost less than $10 when purchased in quantity.

Small radar devices such as the RFBeam Microwave K-LC1a radio transceiver cost less than $10 when purchased in quantity.

It’s time we make radar a viable option for DIY projects and consumer devices by developing low-cost, easy-to-use, capable technology and bridging the knowledge gap!
Today you can buy small radar sensors for less than $10. Couple this with learning practical radar processing methods, and you can solve a critical sensing problem for your project.

Learn by doing. I created the MIT short-course “Build a Small Radar Sensor,” where students learn about radar by building a device from scratch. Those interested can take the online course for free through MIT Opencourseware or enroll in the five-day MIT Professional Education course.

Dive deeper. My soon-to-be published multimedia book, Small and Short-Range Radar Systems, explains the principles and building of numerous small radar devices and then demonstrates them so readers at all levels can create their own radar devices or learn how to use data from off-the-shelf radar sensors.

This is just the beginning. Soon small radar sensors will be everywhere.

ARM mbed Platform for Bluetooth Smart Applications

OLYMPUS DIGITAL CAMERAThe nRF51822-mKIT simplifies and accelerates the prototyping process for Bluetooth Smart sensors connecting to the Internet of Things (IoT). The platform is designed for fast, easy, and flexible development of Bluetooth Smart applications.

The nRF51822 system-on-chip (SoC) combines a Bluetooth v4.1-compliant 2.4-GHz multiprotocol radio with an ARM Cortex-M0 CPU core on a single chip optimized for ultra-low-power operation. The SoC simplifies and accelerates the prototyping process for Bluetooth Smart sensors connecting to the IoT.

The nRF51822-mKIT’s features include a Bluetooth Smart API, 31 pin-assignable general-purpose input/output (GPIO), a CMSIS-DAP debugger, Programmable Peripheral Interconnect (PPI), and the ability to run from a single 2032 coin-cell battery.

Through mbed, the kit is supported by a cloud-based approach to writing code, adding libraries, and compiling firmware. A lightweight online IDE operates on all popular browsers running on Windows, Mac OSX, iOS, Android, and Linux OSes. Developers can use the kit to access a cloud-based ARM RVDS 4.1 compiler that optimizes code size and performance.

The nRF51822-mKIT costs $59.95.

Nordic Semiconductor ASA

A Personal Hackerspace in Lyon, France

Jean Noël Lefebvre, of Lyon, France, is the inventor of the Ootsidebox touchless technology, an innovative interface that enables adding touchless technology to an existing tablet. (Watch the Elektor.LABS video interview with Lefebvre to find out more about Ootside box and how it works).

Recently, Lefebvre shared with Circuit Cellar photos of his workspace, which he prefers to call his “personal hackerspace”  where he conceives inventive ideas and builds them.


Lefebvre’s desk reflects his new project.

His desk has an old oscilloscope, with only two inputs. “I have to upgrade it as soon as possible,” he says.

He is working on a shield for the Arduino UNO board on his desk, which is also where he keeps a Weller soldering iron with specific tools for surface mount devices (SMDs).

“On the screen of the computer you can see the logo of my project Ootsidebox and also the logo of Noisebridge, the San Francisco hackerspace.”

A diverse library

A diverse library

Lefebvre says his library is filled with “a lot of good books (old and modern)” covering many different topics and skills, including electronics, software, signal processing, cryptography, physics, biology, mathematics, and inventors’ biographies.

What is he currently working on in his hackerspace?

“I’m working on my own invention: a touchless gesture user Interface based on electric-fields (E-fields) sensing,” he says. “It’s an open-source  and open-hardware project, compatible with the Arduino environment.”

You can learn more about how his project is being shared on the Elektor.LABS website.

Storage for some of Lefebvre's stock components

Storage for some of Lefebvre’s stock components

Although Lefebvre is currently working alone in his “personal hackerspace” at his family’s home, his dream is to go to San Francisco, CA, and work out of the well-equipped Noisebridge hackerspace.

A few years ago, he says, big ideas and innovations in technology started in garages.  “Today this will take place in hackerspaces, where creativity and technical skills are omnipresent,” he says. “By making stuff in such a place, you are fully connected with a worldwide network of creative people of different backgrounds, and this synergy highly accelerates the innovation process.”

You can view pictures and video Lefebvre posted from his last Noisebridge visit.  And you can follow Lefebvre and his work on Twitter.

Internet of Things Challenge: WIZ55io Modules Moved Fast

As soon as the WIZNet Connect the Magic 2014 Design Challenge launched on March 3, 2014, Internet of Things (IoT) innovators—from professional electrical engineers to creative electronics DIYers—around world began requesting free WIZnet WIZ550io Ethernet controller modules. And due to the popular demand for the modules, the supply of free units ran out on March 11.

Although free modules are no longer available, anyone with a WIZ550io Ethernet module, or W5500 chip, may participate in the competition.

Participants can purchase eligible parts at shopwiznet.com or shop.wiznet.eu.

The WIZ550io is an auto-configurable Ethernet controller module that includes the W5500 (TCP/IP-hard-wired chip and PHY embedded), transformer, and an RJ-45 connector. The module has a unique, embedded real MAC address and auto network configuration capability.

WIZnet's WIZ550io auto configurable Ethernet controller module includes a W5500, transformer, & RJ-45.

WIZnet’s WIZ550io auto configurable Ethernet controller module includes a W5500, transformer, & RJ-45.

The W5500 chip is a Hardwired TCP/IP embedded Ethernet controller that enables Internet connection for embedded systems using Serial Peripheral Interface (SPI).



The challenge is straightforward. Participants must implement a WIZ550io Ethernet module, or W5500 chip, in an innovative electronics design for a chance to win a share of $15,000 in prizes. The project submission deadline is August 3, 2014. For more information about the challenge, visit http://circuitcellar.com/wiznet2014/.

Sponsor: WIZnet

A Fundamental Rule of Grounding (EE Tip #124)

Quantum mechanics notwithstanding, our world is analog. And so despite our fascination with everything digital, we need interfaces to provide bridges for our analog reality to cross over to the digital paradigm and then back again. One may ask: Is there a common denominator that binds these two worlds together regardless of their many conceptual differences? In my mind, it is grounding.

The fundamental rule for grounding is depicted in Figure 1. By “ground” I mean the common 0 V potential to which signals are referenced. The “chassis ground”, if grounding conductors had 0 Ω impedance, would also be 0 V—but, unfortunately, it never is. Yet there are still systems that are sufficiently insensitive to ground potential differences. They use the chassis for the signal and power returns. At one time, this was the way cars had been wired.

Figure 1: Botth sections, A and B, may be on the same PCB with separate ground planes (e.g., analog and digital). The diodes and the capacitor between the planes limit potential differences due to ground bounce, etc. Broken lines inside boxes 1 and 3 indicate ground referenced, non-symmetrical inputs and outputs.

Figure 1: Botth sections, A and B, may be on the same PCB with separate ground planes (e.g., analog and digital). The diodes and the capacitor between the planes
limit potential differences due to ground bounce, etc. Broken lines inside boxes 1 and 3 indicate ground referenced, non-symmetrical inputs and outputs.

Figure 1a shows circuits sharing a common ground run. Notice that the output or the highest current drawing stage (1) must be the closest to the common point to minimize the voltage developed by that stage current over the grounding conductor. Also notice that the input signal and its return must be tied to the input block (3). Internal signal returns (grounds) are shown by broken lines. Returning inputs or outputs anywhere else would superimpose the noise from stages 1, 2, and 3 on the input signal. Figure 1b shows the approach often used in RF equipment. There is no sharing of grounds; they are all individually tied to a single point. Each circuit A and B can occupy its own PCB or they can be on a single PCB, their ground planes separate, such as analog and digital circuits. The grounds come together at the point G, where the chassis is also connected. Where there are a few inches of wire tying the individual grounds together, it is a good idea to insert fast signal diodes and a capacitor as shown between the separate ground runs. Any potential difference developed between the separate grounds due to finite impedance of wiring, as shown in Figure 1, will be attenuated and clamped by the three components. Note that the “capacitor” should in fact be a parallel combination of a number of capacitors, depending on the application, to guarantee performance across the spectrum. The following are typically used: 100 pF, 1 nF, 10 nF, 0.1 μF, and 1 μF.

In safety-critical systems such as aircraft comprising two or more subsystems enclosed in metal cabinets, such as shown in Figure 2, only currents from lightning or other interference suppressed by the EMC blocks is allowed to be returned to the chassis.

Figure 2: Connecting subsystems to avoid ground loops

Figure 2: Connecting subsystems to avoid ground loops

Power needs to be delivered by twisted pairs and all the returns connected to the chassis at a single point. If the signal grounds of the electronics are not allowed to be connected to the chassis, which depends on the system architecture, a combination of diodes, a capacitor, and a resistor as shown needs to be used to prevent ground loops as well as parasitic feedbacks between the electronics and the metal cabinet.

The subsystem enclosures shown with dotted lines connect to the chassis by mounting screws or straps. Most of today’s avionic equipment uses isolated power supplies. There is no galvanic connection between the power return and the internal signal ground to eliminate ground loops, yet the enclosures need to be connected to the internal grounds to eliminate parasitic feedbacks through capacitive coupling; but then they would create ground loops. Some system architectures require signals working with their own ground, isolated from the chassis, to prevent ground loops. To compensate for the parasitic capacitances existing due to the proximity of the metal enclosure to the components and the EMI/lightning protection, the resistor, capacitor, diode combination (as mentioned above) is used, with typical values of resistor about 10 kΩ and capacitance less than 10 μF. The capacitance is again a parallel combination of smaller capacitors to suppress the desired frequency spectrum.—George Novacek, “My Analog World: The Significance of Grounding,” Circuit Cellar 244, 2010.


AllianceMemoryThe AS4C4M16D1-5TIN, the AS4C8M16D1-5TIN, the AS4C16M16D1-5TIN, and the AS4C32M16D1-5TIN are high-speed CMOS double data rate synchronous DRAMs (DDR SDRAMs). The devices feature densities of 64 MB (AS4C4M16D1-5TIN), 128 MB (AS4C8M16D1-5TIN), 256 MB (AS4C16M16D1-5TIN), and 512 MB (AS4C32M16D1-5TIN) with a –40°C to 85°C industrial temperature range.

The DDR SDRAMs provide reliable drop-in, pin-for-pin-compatible replacements for industrial, medical, communications, and telecommunications products requiring high memory bandwidth. The devices are well-suited for high performance in PC applications. Internally configured as four banks of 1M, 2M, 4M, or 8M word × 16 bits with a synchronous interface, the DDR SDRAMs operate from a single 2.5-V (± 0.2 V) power supply and are lead- and halogen-free.

The AS4C4M16D1-5TIN, the AS4C8M16D1-5TIN, the AS4C16M16D1-5TIN, and the AS4C32M16D1-5TIN feature a 200-MHz clock rate and are available in a 66-pin TSOP II package with a 0.65-mm pin pitch. The 128-, 256-, and 512-MB devices are also available in a TFBGA package.

The DDR SDRAMs provide programmable read or write burst lengths of 2, 4, or 8. An auto pre-charge function provides a self-timed row pre-charge initiated at the end of the burst sequence. Easy-to-use refresh functions include auto- or self-refresh. A programmable mode register enables the system to choose a suitable mode for maximum performance.
Pricing for the AS4C4M16D1-5TIN, the AS4C8M16D1-5TIN, the AS4C16M16D1-5TIN, and the AS4C32M16D1-5TIN starts at $0.90 per piece.

Alliance Memory, Inc.

A Low-Cost Connection to the IoT

In Circuit Cellar’s March issue, columnist Jeff Bachiochi tests the services of a company he says is “poised to make a big impact” on the Internet of Things (IoT).

This shows the I2C interface Bachiochi designed to enable available clamp-on current sensors to be monitored. He added four of these circuits to a PCB, which includes the circuitry for an imp card.

This shows the I2C interface Bachiochi designed to enable available clamp-on current sensors to be monitored. He added four of these circuits to a PCB, which includes the circuitry for an imp card.

Established in 2011, Electric Imp offers a flexible connectivity platform meant to enable any device to be connected to the IoT. The platform, called the “imp,” provides an SD-card sized module (including an 802.11b/g/n Wi-Fi radio package) that can be installed on any electronic device to go online. A powerful processor runs the imp OS.

“You only need to supply an SD card socket (and a few other components) to your product to give it connectivity,” Bachiochi says. “The imp’s processor has the power to run your entire product if you wish, or it can be connected via one of the supported serial protocols. The imp OS provides secure connectivity to the imp cloud. The imp cloud keeps your imp updated with the latest firmware, features online development tools, and provides cloud-side services for every imp in the field.”

“As with many cloud service organizations, development is generally free,” Bachiochi adds. “Once you’ve committed and have product rollout, the service will charge for its use. This could be a flat fee, a per-connection or data throughput fee, or a combination of fees. Basically you (or your customer) will have to pay to have access to the information, which pays for the support framework that keeps it all working.”

In his article, Bachiochi dives into a straightforward data-collection project to demonstrate how to use the imp in a product. The goal of his application was to log the activity of 220-V water pump and twin water softeners.  The project is the launching point for his comprehensive and detailed look at the imp’s hardware, software, and costs.

“It’s easy to design product hardware to use the imp,” he says. “There are two imp models, a card that can be inserted into an SD-type socket or an on-board module that is soldered into your product. Each version has advantages and disadvantages.”

Regarding software, Bachiochi says:

“Developing an imp application requires two parts to provide Wi-Fi access to your project: the device code (running in the imp) and the agent code (running on the imp cloud). The imp cloud, which is your connection to your device via the imp APIs, provides you with a development IDE. Web-based development means there is nothing else you need to purchase or install on your PC. Everything you need is available through your browser anytime and anywhere.”

Bachiochi also discusses the Electric Imp platform’s broader goals. While an individual can use the imp for device connectivity, a bigger purpose is to enable manufacturers to provide convenient Internet access as part of their product, Bachiochi says.

“The imp has two costs: The hardware is simple, it currently costs approximately $25 for an imp card or module. If you are using this in your own circuit within your own network, then you’re done,” he says. “If you want to roll out a product for sale to the world, you must take the next step and register for the BlinkUp SDK and Operations Console, which enable you to create and track factory-blessed products.”

BlinkUp, according to the Electric Imp website, integrates smoothly into apps and enables manufacturers and their customers to quickly connect products using a smartphone or tablet. The Operations Console enables tracking product activity and updating product firmware at any time, Bachiochi says.

The imp offers more than a low-cost way for DIYers and developers to connect devices to the Internet, Bachiochi says. A designer using the imp can save project costs by eliminating a microcontroller, he says. “Almost any peripheral can be easily connected to and serviced by the imp’s 32-bit Cortex M3 processor running the imp OS. All code is written in Squirrel.”

Bachiochi’s comprehensive article about his imp experience and insights can be found in the March issue, now available for membership download or single-issue purchase.

Bachiochi used the Electric IMP IDE to develop this code. Agent code on the top left runs on the imp cloud server. The device code on the top right is downloaded into the connected imp.

Bachiochi used the Electric IMP IDE to develop this code. Agent code on the top left runs on the imp cloud server. The device code on the top right is downloaded into the connected imp.

Wireless Product Regulations (EE Tip #123)

Are you working on a wireless design that you’d like to bring to market? If so, be sure to anticipate regulatory constraints right from the start. Planning upfront will save you a lot of time, money, and hassle.

Electrical engineer Robert Lacoste notes:

Unless you’re working on a prototype that won’t ever leave your lab, there is a high probability that you will need to comply with some regulations. FCC and CE are the most common, but you’ll also find local regulations as well as product-class requirements for a broad range of products, from toys to safety devices to motor-based machines. (Refer to my article “CE Marking in a Nutshell,” Circuit Cellar 257, for more information.CE Mark

Let’s say you design a wireless gizmo for the U.S. market and later find that your customers want to use it in Europe. This means you lose years of work, as well as profits, because you overlooked your customers’ needs and the regulations in place in different locales.

When designing a wireless gizmo that will be used outside the U.S., having adequate information from the start will help you make good decisions. An example would be selecting a worldwide-enabled band like the ubiquitous 2.4 GHz. Similarly, don’t forget that EMC/ESD regulations require that nearly all inputs and outputs should be protected against surge transients. If you forget this, your beautiful, expensive prototype may not survive its first day at the test lab.

Lacoste’s full article appeared in Circuit Cellar’s anniversary issue, CC25.

Miniature PECL and LVDS Oscillators

PrecisionDevicesThe PDI Model LV5 and PE5 Series of oscillators provide precision timing in a 3.2-mm × 5-mm ceramic hermetically sealed package. The LV5 is a low-voltage differential signaling (LVDS) ocsillator. The PE5 is a PECL oscillator.

These high-performance clock oscillators offer low integrated phase jitter (0.2 pS for the LV5 and 0.3 pS for the PE5). They are available in frequencies up to 200 MHz and feature a –40°C to 85°C industrial temperature range. Stabilities can be held down to ±25 ppm (depending on temperature range).

Contact Precision Devices for pricing.

Precision Devices, Inc.

Traveling With a “Portable Workspace”

As a freelance engineer, Raul Alvarez spends a lot of time on the go. He says the last four or five years he has been traveling due to work and family reasons, therefore he never stays in one place long enough to set up a proper workspace. “Whenever I need to move again, I just pack whatever I can: boards, modules, components, cables, and so forth, and then I’m good to go,” he explains.

Raul_Alvarez_Workspace _Photo_1

Alvarez sits at his “current” workstation.

He continued by saying:

In my case, there’s not much of a workspace to show because my workspace is whichever desk I have at hand in a given location. My tools are all the tools that I can fit into my traveling backpack, along with my software tools that are installed in my laptop.

Because in my personal projects I mostly work with microcontroller boards, modular components, and firmware, until now I think it didn’t bother me not having more fancy (and useful) tools such as a bench oscilloscope, a logic analyzer, or a spectrum analyzer. I just try to work with whatever I have at hand because, well, I don’t have much choice.

Given my circumstances, probably the most useful tools I have for debugging embedded hardware and firmware are a good-old UART port, a multimeter, and a bunch of LEDs. For the UART interface I use a Future Technology Devices International FT232-based UART-to-USB interface board and Tera Term serial terminal software.

Currently, I’m working mostly with Microchip Technology PIC and ARM microcontrollers. So for my PIC projects my tiny Microchip Technology PICkit 3 Programmer/Debugger usually saves the day.

Regarding ARM, I generally use some of the new low-cost ARM development boards that include programming/debugging interfaces. I carry an LPC1769 LPCXpresso board, an mbed board, three STMicroelectronics Discovery boards (Cortex-M0, Cortex-M3, and Cortex-M4), my STMicroelectronics STM32 Primer2, three Texas Instruments LaunchPads (the MSP430, the Piccolo, and the Stellaris), and the following Linux boards: two BeagleBoard.org BeagleBones (the gray one and a BeagleBone Black), a Cubieboard, an Odroid-X2, and a Raspberry Pi Model B.

Additionally, I always carry an Arduino UNO, a Digilent chipKIT Max 32 Arduino-compatible board (which I mostly use with MPLAB X IDE and “regular” C language), and a self-made Parallax Propeller microcontroller board. I also have a Wi-Fi 3G TP-LINK TL-WR703N mini router flashed   with OpenWRT that enables me to experiment with Wi-Fi and Ethernet and to tinker with their embedded Linux environment. It also provides me Internet access with the use of a 3G modem.

Raul_Alvarez_Workspace _Photo_2

Not a bad set up for someone on the go. Alvarez’s “portable workstation” includes ICs, resistors, and capacitors, among other things. He says his most useful tools are a UART port, a multimeter, and some LEDs.

In three or four small boxes I carry a lot of sensors, modules, ICs, resistors, capacitors, crystals, jumper cables, breadboard strips, and some DC-DC converter/regulator boards for supplying power to my circuits. I also carry a small video camera for shooting my video tutorials, which I publish from time to time at my website (www.raulalvarez.net). I have installed in my laptop TechSmith’s Camtasia for screen capture and Sony Vegas for editing the final video and audio.

Some IDEs that I have currently installed in my laptop are: LPCXpresso, Texas Instruments’s Code Composer Studio, IAR EW for Renesas RL78 and 8051, Ride7, Keil uVision for ARM, MPLAB X, and the Arduino IDE, among others. For PC coding I have installed Eclipse, MS Visual Studio, GNAT Programming Studio (I like to tinker with Ada from time to time), QT Creator, Python IDLE, MATLAB, and Octave. For schematics and PCB design I mostly use CadSoft’s EAGLE, ExpressPCB, DesignSpark PCB, and sometimes KiCad.

Traveling with my portable rig isn’t particularly pleasant for me. I always get delayed at security and customs checkpoints in airports. I get questioned a lot especially about my circuit boards and prototypes and I almost always have to buy a new set of screwdrivers after arriving at my destination. Luckily for me, my nomad lifestyle is about to come to an end soon and finally I will be able to settle down in my hometown in Cochabamba, Bolivia. The first two things I’m planning to do are to buy a really big workbench and a decent digital oscilloscope.

Alvarez’s article “The Home Energy Gateway: Remotely Control and Monitor Household Devices” appeared in Circuit Cellar’s February issue. For more information about Alvarez, visit his website or follow him on Twitter @RaulAlvarezT.

Internet of Things Challenge: WIZnet Connect the Magic 2014 Launches

Elektor International Media (EIM) and WIZnet Co, Ltd today officially launched the WIZnet Connect the Magic 2014 Design Challenge, which is a five-month-long contest for electrical engineers, students, and DIYers to develop innovative, ’Net-connected electronic systems around a WIZNet WIZ550io Ethernet controller module or W5500 chip.

According to the Challenge’s rules, entrants must use at least one WIZnet WIZ550io or W5500 chip in a project. Entries will be judged on their technical merit, originality, usefulness, cost-effectiveness, and design optimization. Winners will receive a share of $15,000 in prizes and recognition in Elektor and Circuit Cellar magazines. The entry submission deadline is August 3, 2014.

WIZnet's WIZ550io auto configurable Ethernet controller module includes a W5500, transformer, & RJ-45.

WIZnet’s WIZ550io auto configurable Ethernet controller module includes a W5500, transformer, & RJ-45.

The WIZ550io is an auto-configurable Ethernet controller module that includes the W5500 (TCP/IP-hard-wired chip and PHY embedded), transformer, and an RJ-45 connector. The module has a unique, embedded real MAC address and auto network configuration capability. The W5500 chip is a Hardwired TCP/IP embedded Ethernet controller that enables Internet connection for embedded systems using Serial Peripheral Interface (SPI).

“The WIZnet Connect the Magic 2014 Design Challenge is an excellent opportunity for engineers, designers, and students to build ’Net-connected systems with WIZnet’s WIZ550io auto-configurable Ethernet controller module and W5500 chip,” said C. J. Abate, Editor in Chief for EIM’s Circuit Cellar magazine.

The challenge is intended to engage more engineers and innovators in the Internet of Things revolution, which has become a major focus for electronics developers worldwide during the past several months.


WIZnet W5500 chip

“The engineers, students, and academics that read our publications and comprise our community see the Internet of Things as more than a convenience. They see it as an opportunity—that is, an opportunity to create cutting-edged connected devices and bring them to market,” Abate said. “Thus, it’s our job to introduce our community members to the best components and tools to achieve their IoT-related design goals. We’re doing that by managing this challenge for our partner, WIZnet, whose W5500 chip and WIZ550io Ethernet module enable designers to quickly develop ’Net-connected systems.”

WIZnet has made available a limited number of free WIZ550io Ethernet controller modules for use in the WIZnet 2014 Connect the Magic Design Challenge. To submit a request for a free WIZ550io module, eligible participants can fill out an online sample request form at http://circuitcellar.com/wiznet2014/samplerequest/.

WIZnet is a private fabless semiconductor company founded in 1998 in Korea. WIZnet provides IOcP (Internet Offload co-Processors) and HW TCP/IP chips, best fitted for low-end Non-OS devices connecting to the Ethernet for the internet of things. Visit www.wiznet.co.kr/ for more information.

Elektor International Media (EIM) is the world’s leading source of essential technical information and electronics products for pro engineers, electronics designers, and the companies seeking to engage them. Each day, its international team develops and delivers high-quality content—via a variety of media channels (e.g., magazines, video, digital media, and social media) in several languages—relating to embedded systems, electronics design, DIY electronics, and hi-fi audio. EIM’s brands include Elektor, Circuit Cellar, audioXpress, and Voice Coil. Visit www.elektor.com for more information.

Design Challenge Contact
Challenge Administration
EIM/Circuit Cellar

WIZnet Support
Americas: support_team@wiznettechnology.com
Asia: support@wiznet.hk
China: support-bj@wiznet.hk
EU: support@wiznet.eu
Korea: support@wiznet.co.kr

Circuit Cellar Editorial
Mary Wilson
Managing Editor

Electrical Engineering Crossword (Issue 284)

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



1.    CROSSEDFIELDAMPLIFIER—This vacuum tube is capable of high output power [three words]
3.    HYPERVISOR—Produces and runs virtual machines
5.    DYNATRON—Uses negative resistance to keep a tuned circuit oscillating
8.    ULTRAVIOLETLIGHT—Gives some substances “a healthy glow” [two words]
13.    ZEROMOMENTPOINT—A moment of respite for robots [three words]
14.    THERMOSONIC—Connects to silicon ICs
17.    CATSWHISKER—An outdated electronic component mainly used in antique radios [two words]
18.    FLEMINGVALVE—Invented in the early 1900s, this was known as the first vacuum tube [two words]
19.    BACKBONE—Makes LANs connect


2.    DEMODULATOR—Recovers information from a regulated waveform
4.    SQUEGGING—This type of circuit oscillates erratically
5.    DOWNMIXING—Audio manipulation process
6.    REYNOLDSNUMBER—Used for flow pattern predictions [two words]
7.    LATENCY—Used with bandwidth to ascertain network connection speed
9.    THICKFILM—This type of chip resistor is commonly used in electronic and electrical devices [two words]
10.    DYNAMIC—Its memory is volatile
11.    CRYOTRON—Operates via superconductivity
12.    NETMASK—Creates neighborhoods of IP addresses
15.    HOROLOGY—E.g., clepsydras, chronometers, and sundials
16.    SEEBECK—An effect that creates electricity