October Circuit Cellar: Sneak Preview

The October issue of Circuit Cellar magazine is out next week! Smart Home technologies, Smart Farming, antenna arrays, rugged SBCs and COMs—this 84-page publication gathers up a great selection of embedded electronics articles for your reading pleasure.

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Here’s a sneak preview of October 2019 Circuit Cellar:

TECHNOLOGIES FOR A CONNECTED WORLD

Smart Home Technologies
By Jeff Child
The evolution of Smart Homes is about more than pure convenience. Smart Home technologies are leveraging IoT concepts to improve energy efficiency and security, thanks to intelligent, connected devices. The topic encompasses things like power-saving motor control systems, predictive maintenance, cloud-based voice assistance, remote monitoring and more. In this article, Circuit Cellar Chief Editor Jeff Child examines the MCU and analog ICs that are serving the needs Smart Home system developers.

MQ Telemetry Transport
By Jeff Bachiochi
Better known by the acronym MQTT, this lightweight messaging protocol is designed to minimize network bandwidth and device resource requirements. In this article, Jeff sets out to use MQTT via a cloud setup that he can do locally. For this, he turns to Eclipse Mosquitto, an open source message broker that implements the MQTT protocol. Jeff steps through the nitty gritty details of his implementation.

LoRa (Part 1)
By Bob Japenga
In this new article series, Bob discusses LoRa—the Long Range spread spectrum modulation technique that promises to solve a number of the key issues in fulfilling the wireless IoT requirements. In Part 1, Bob starts with an introduction to LoRa, looking at what it is, what are its limitations and how those limitations affect how we use this technology.

Smart Farming Device Gives Plants a Voice
By Andrei Florian
Smart Farming has many aspects, and among these the agriculture side. In this project article, Andrei discusses SmartAgro, a device that combines field autonomy with ease of use, allowing farmers to give their plants a “voice.” It lets you visualize the temperature, soil humidity, UV radiation and more wherever you are, in real time and take action when it is most needed—whether that means turning on an irrigation system or preparing for cultivation.

 
RESOURCES FOR ENGINEERS

Product Focus: Rugged SBCs
By Jeff Child
Single board computers are used in such a broad sweep of applications—some that must operate in harsh environmental conditions. Rugged SBCs offer a variety of attributes to serve such needs, including extended temperature range, high shock and vibration resilience and even high humidity protection. This Product Focus section updates readers on this technology trend and provides a product album of representative rugged SBCs.

An Intro to Antenna Arrays
By Robert Lacoste
As an expert in RF technology, Robert has deep knowledge about antennas. And in this era of IoT, his expertise more relevant than ever. That’s because every wireless device has some kind of antenna and these antennas are often the root cause of engineering headaches. With that in mind, in this article Robert discusses the math, technology and design issues that are basic to antenna arrays.

Using Digital Potentiometers
By Stuart Ball
A digital potentiometer probably can’t be considered the most glamorous of electronic components. But it is easy to use and versatile. In this article, Stuart digs into the uses, advantages and disadvantages of the digital potentiometer, including how they contrast to mechanical potentiometers.

Semiconductor Fundamentals (Part 2)
By George Novacek
In Part 1 George examined the basic structures that make semiconductors work. But a lot more needs to be said about diodes, which are a key element of semiconductors. In Part 2, George dives deeper, this time looking at the current flow, depletion layer and electron physics that are involved in diode operations. He covers various types of diodes and the details of their operations.

A Hardware Random Number Generator
By Devlin Gualtieri
Men first walked on the Moon fifty years ago. On the same week as that historic event, Dev divided his time between watching the event on television and building a unique desktop novelty circuit, a random digit generator. This circuit used a Nixie tube for display and a handful of TTL integrated circuits to implement a linear feedback shift register. In this article, Dev updates his original design using the CMOS digital circuits available today and a 7-segment LED display. He also presents an improved version that uses a Microchip PIC MCU.


MICRCONTROLLERS DO IT ALL

Application-Specific MCUs
By Jeff Child
In contrast to microprocessors, microcontrollers tend to be used for specific applications. But even among MCUs, there’s distinct difference between general purpose MCUs and MCUs that are designed for very specific application segments, or even sub-segments. Circuit Cellar Chief Editor Jeff Child examines this class of MCUs that target everything from factory automation to appliance control.

The Laser Harp
By Alex Hatzis
Normally, you’d think that taking the strings out of a harp would be a downgrade. But in this article, Cornell student Alex Hatzis presents a system that does just that—replacing the harp strings with red lasers. Phototransistors are used to detect when the beams are intercepted by a person’s hand playing the harp, and some convincing real-time sound synthesis helps to create a new, high tech instrument.

 

 

 

September Circuit Cellar: Sneak Preview

The September issue of Circuit Cellar magazine is out next week! This 84-page publication stitches together a fine tapestry of fascinating embedded electronics articles crafted for your reading pleasure.

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Here’s a sneak preview of September 2019 Circuit Cellar:

TECHNOLOGY FOR SECURITY, SENSORS & THE IoT

Security Solutions for IoT
By Jeff Child
In this IoT era of connected devices, microcontrollers have begun taking on new roles and gaining new capabilities revolving around embedded security. MCUs are embedding ever-more sophisticated security features into their devices-both on their own and via partnerships with security specialists. Here, Circuit Cellar’s Editor-in-Chief, Jeff Child, looks at the latest technology and trends in MCU security.

Electromagnetic Fault Injection: A Closer Look
By Colin O’Flynn
Electromagnetic Fault Injection (EMFI) is a powerful method of inserting faults into embedded devices, but what does this give us? In this article, Colin dives into a little more detail of what sort of effects EMFI has on real devices, and expands upon a few previous articles to demonstrate some attacks on new devices.
 
Product Focus: IoT Gateways
By Jeff Child
IoT gateways are a smart choice to facilitate bidirectional communication between IoT field devices and the cloud. Gateways also provide local processing and storage capabilities for offline services as well as near real-time management and control of edge devices. This Product Focus section updates readers on these technology trends and provides a product gallery of representative IoT gateways.
 
Comparing Color Sensor ICs
By Kevin Jensen
Driven by demands from mobile phone, display and specialty lighting equipment manufacturers, the need for sophisticated and accurate chip-scale color and spectral sensors has become stronger than ever. In this article, ams’ Kevin Jensen describes the types of optical sensors and detectors. He also provides ideas on evaluating the suitability of each type for specific applications.

PC-BASED SOLUTIONS FOR EMBEDDED SYSTEMS
 
Mini-ITX, Pico-ITX and Nano-ITX Boards
By Jeff Child
Products based on the various small-sized versions of the ITX form factor—Mini-ITX, Pico-ITX and Nano—ITX-provide system developers with complete PC-functionality and advanced graphics. Circuit Cellar Chief Editor Jeff Child explores the latest technology trends and product developments in these three ITX architectures.
 
Using Small PCs in New Ways
By Wolfgang Matthes
Even simple MCU-based projects often require some sort of front panel interface. Traditionally such systems had to rely on LEDs and switches for such simple interfaces. These days however, you can buy small, inexpensive computing devices such as mini-PCs and notebook computers and adapt them to fill those interfacing roles. In this article, Wolfgang steps you through the options and issues involved in connecting such PC-based devices to an MCU-based environment.



FOCUS ON MICROCONTROLLERS
 
Guitar Game Uses PIC32 MCU
By Brian Dempsey, Katarina Martucci and Liam Patterson
Guitar Hero has been an extremely popular game for decades. Many college kids today who played it when they were kids still enjoy playing it today. These three Cornell students are just such fans. Learn how they used Microchip’s microcontroller and 12-bit DAC to craft their own version that lets them play any song they wish by using MIDI files.
 
Offloading Intelligence
By Jeff Bachiochi
While some embedded systems do just fine with a single microcontroller, there are situations when offloading some processing into a second processing unit, such as a second MCU, offers a lot of advantages. In this article, Jeff explores this question in the context of a robotic system project that uses Arduino and an external motor driver.
 
Building a Portable Game Console
By Juan Joel Albrecht and Leandro Dorta Duque
32-bit MCUs can do so much these days—even providing all the needed control functionality for a gaming console. Along just those lines, learn how these three Cornell students built a portable game console that combines a Microchip PIC32 MCU embedded in a custom-designed 3D-printed case, printed circuit board and in-house gameplay graphics. The device includes a 320 x 240 TFT color display.
 


… AND MORE FROM OUR EXPERT COLUMNISTS
 
Variable Frequency Drive Part 2
By Brian Millier
In Part 1 Brian started to describe the process he used to convert a 3-phase motor and OEM Variable Frequency Drive (VFD) controller—salvaged from his defunct clothes washer—into a variable speed drive for his bandsaw. In this article, he completes the discussion this tim,e covering the Cypress Semi PSoC5LP SoC he used, the software design and more.
 
Semiconductor Fundamentals Part 1
By George Novacek
Embedded systems—or even modern electronics in general—couldn’t exist without semiconductor technology. In this new article series, George delves into the fundamentals of semiconductors. In Part 1 George examines the math, chemistry and materials science that are fundamental to semiconductors with a look at the basic structures that make them work.
 

 

August Circuit Cellar: Sneak Preview

The August issue of Circuit Cellar magazine is out next week! This 84-page publication rustles up a powerful herd of compelling embedded electronics articles prepared for your reading pleasure.

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Here’s a sneak preview of August 2019 Circuit Cellar:

MCU AND EMBEDDED SYSTEM TECHNOLOGIES

MCUs for Driverless Cars
By Jeff Child
Driverless cars are steadily advancing toward becoming a mainstream phenomenon. Building toward that goal, chip vendors are evolving their driver assistance technologies into complete driver replacement solutions. These solutions make use of powerful microcontroller solutions to analyze a car’s surroundings, process the information and employ control functionality to steer cars safely. Circuit Cellar Chief Editor Jeff Child examines the MCU technology and product trends that are key to driverless vehicle evolution.

Product Focus: Small and Tiny Embedded Boards
By Jeff Child
An amazing amount of computing functionality can be squeezed on to a small form factor board these days. These small—and even tiny—board-level products meet the needs of applications where extremely low SWaP (size, weight and power) beats all other demands. This Product Focus section updates readers on this technology trend and provides a product album of representative small and tiny embedded boards.

Portable Digital Synthesizer
By T.J. Hurd and Ben Roberge
Gone are the days when even a basic music synthesizer was a bulky system requiring highly specialized design knowledge. These two Cornell students developed a portable musical synthesizer using a Microchip PIC32 MCU. The portable system performs digital audio synthesis on the fly and produces sounds that range from simple sine waves to heavily modulated waveforms.

Displays for Embedded Systems
By Jeff Child
Thanks to advances in displays and innovations in graphics ICs, embedded systems can now routinely feature sophisticated graphical user interfaces. What used to require a dedicated board-level graphics/video board, now can be integrated into a chip or just a part of a chip. Circuit Cellar Chief Editor Jeff Child dives into the latest technology trends and product developments in displays for embedded systems.

Building a Twitter Emote Robot
By Ian Kranz, Nikhil Dhawan and Sofya Calvin
Social media is so pervasive these days that it’s hard to image life without it. But digital interactions can be isolating because the physical feedback component gets lost. Using PIC32 MCU technology, these three Cornell students built an emotionally expressive robot which physically reacts to tweets in a live setting. Users can tweet to the robot’s Twitter account and receive near instant feedback as the robot shares its feelings about the tweet via physical means such as sounds, facial expressions and more.

Understanding the Role of Inference Engines in AI
By Geoff Tate, Flex Logix
Artificial Intelligence offers huge benefits for embedded systems. But implementing AI well requires making smart technology choices, especially when it comes to selected a neural inferencing engine. In this article, Flex Logix CEO Geoff Tate explains what inferencing is, how it plays into AI and how embedded system designers can make sure they are using the right solution for their AI processing.


FUN WITH LIGHT AND HEAT

Watt’s Up with LEDs?
By Jeff Bachiochi
When Jeff puts his mind to a technology topic, he goes in deep. In this article, he explores all aspects of LED lighting—including the history, math, science and technology of LEDs. He discusses everything from temperature issues to powering LEDs. After purchasing some LEDs, Jeff embarks on a series of tests and shares his results and insights.

Automating the Art of Toast
By Michael Xiao and Katie Bradford
The emergence of culinary robotics and automation has already begun to revolutionize the way we prepare our meals. In this article, learn how these two Cornell undergraduates designed an advanced toaster that’s able to toast any pattern—image, text or even today’s weather—onto a piece of bread. The project makes use of Microchip’s MIC32 MCU and a Raspberry Pi Zero W board.

Build an RGB LED Controller
By Dirceu R. Rodrigues Jr.
There are a lot of fun and interesting things you can do with LEDs and different ways to control them. In this article, Dirceu describes an alternative approach to control RGB LEDs using the parallel FET dimming technique. He steps through his efforts to design and build an alternative lightning system based on power RGB LEDs. To control them he goes very old school and uses an 8-bit MCU and the BASIC programming language.


… AND MORE FROM OUR EXPERT COLUMNISTS

Energy Monitoring Part 3
By George Novacek
This is the final installment of George’s energy monitoring article series. He discussed the solar power supply in Part 1 and the utility power data acquisition in Part 2. In Part 3, he wraps up the series by looking at the remaining modules that comprise his home energy monitoring setup, including the sensors, the natural gas monitor and the real-time clock.

The Fundamentals of Fuseology
By Robert Lacoste
Just because an electronic device is simple you shouldn’t relegate it to an afterthought in your embedded system design. Such is the case with fuses. Robert explores the fundamentals of this seemingly simple device. In this article, he dives into the history, key specifications and technology of fuses. He also steps you through an experiment to analyze the performance of fuses and shares his results.

Bluetooth Mesh (Part 4)
By Bob Japenga
In this next part of his article series on Bluetooth mesh, Bob looks at how models are defined in the Bluetooth Mesh specification and how practical it is to use them. He looks at the models defined by the Bluetooth SIG and discusses creating your own models for Bluetooth Mesh.

 

 

 

EOG-Controlled Video Game

Eyes as Interface

There’s much be to learned about how electronics can interact with biological signals—not only to record, but also to see how they can be used as inputs for control applications. With ongoing research in fields such as virtual reality and prosthetics, new systems are being developed to interpret different types of signals for practical applications. Learn how these three Cornell graduates use electrooculography (EOG) to control a simple video game by measuring eye movements.

By Eric Cole, Evan Mok and Alex Huang

The human eye naturally acts as a dipole, in which the retina at the back of the eye is negatively charged, and the cornea at the front of the eye is positively charged. EOG is a recording technique that measures this potential difference, and can be used to

Figure 1
Electrode placement for recording. An Ag-AgCl (silver-silver chloride) electrode was placed at each of the labeled points. Points A and B record the EOG signal for the right and left eyes, and point C provides a ground reference.

quantify eye movement [1]. A typical electrode placement pattern for EOG is shown in Figure 1. Each of the electrodes A and B records a voltage related to eye movement, and an electrode at point C serves as a ground reference.

When a user looks left, the cornea is close to electrode B and it records a positive voltage, while the retina is closer to electrode A, yielding a negative voltage. Similarly, looking right produces a negative voltage at B and a positive voltage at A. The difference between VB and VA relative to ground at C changes monotonically with gaze direction, and can be reliably used to model horizontal eye movement.

System Overview

The system we designed uses eye movements to play a video game on a display screen. Electrodes are placed on a player’s head to record only the horizontal EOG signal as shown in Figure 2. This signal is then filtered and amplified via an analog circuit and sent to an ADC on a Microchip Technology PIC32 microcontroller (MCU) (Figure 3). The PIC32 MCU stores the reading as a digital value and uses it to control a cursor on an LCD display screen. A program on the PIC32 continually displays obstacles that move across the screen, and the player moves his or her eyes to control the cursor and avoid obstacles.

Figure 2
Characterization of EOG signal. An example signal output is shown for a gain of approximately 885.

Figure 3
System overview. “Eye recording” is accomplished with the raw electrode signal.

This system is entirely powered without connection to an AC power source, instead using a 9 V battery to provide power for amplification and a chargeable power source to power the PIC32. This choice of a power source was important, because it enforces necessary safety considerations for biomedical recording. Connecting a high voltage source to a human user and accidentally completing a circuit path to AC ground could result in serious injury, so great care was taken to use battery power for this project.

A secondary oscilloscope program was also necessarily designed to satisfy a key safety need: The ability to view the recorded EOG signal and test the recording hardware while the circuit is isolated. A normal oscilloscope cannot be used for this purpose for the reasons stated earlier. Care was also taken to apply and fasten the electrodes properly before every session.

Recording and Application

Three Ag-AgCl (silver-silver chloride) electrodes are placed around the eyes using a skin-safe adhesive gel—one beside each eye, and one on the forehead as a ground reference—at points A, B, and C respectively, in Figure 1. These electrodes provide the gateway between the biological signal and the digital world, detecting the voltage generated by ions at the skin surface and transducing it into an equivalent electron-based signal.

This voltage is generated directly at the eye, and has some attenuation through the skin surface. A typical magnitude of the raw EOG signal is several millivolts. The voltage readings from the two eye electrodes are sent to a Texas Instruments (TI) INA121 differential amplifier, which amplifies the difference between the two input signals. This yields a negative or positive voltage based on direction of eye movement. The INA121 provides low noise, a high common-mode rejection ratio, and is suitable for the high-input impedance requirement associated with recording biological signals. Figure 4 shows the full schematic of the implementation.

A second amplification stage using a TI LM358-based balanced subtractor configuration provides further amplification. This stage reduces the DC voltage component output from the differential amplifier, while further amplifying the difference to a range of 0 to 3.3 V—the scale allowed by the PIC32 MCU’s on-chip ADC. The resulting signal is a voltage centered at approximately 1.6 V when the user looks straight, with about a 1 V increase or decrease when the user looks left or right, respectively. …

Read the full article in the July 348 issue of Circuit Cellar
(Full article word count: 3023 words; Figure count: 6 Figures.)

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Note: We’ve made the October 2017 issue of Circuit Cellar available as a free sample issue. In it, you’ll find a rich variety of the kinds of articles and information that exemplify a typical issue of the current magazine.

July Circuit Cellar: Sneak Preview

The July issue of Circuit Cellar magazine is out next week! This 84-page publication will make a satisfying thud sound when it lands on your desk and it’s crammed full of excellent embedded electronics articles prepared for you.

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Here’s a sneak preview of July 2019 Circuit Cellar:

CONNECTED SYSTEMS IN ACTION

Embedded Computing
in Railway Systems
Railway systems keep getting more advanced. On both the control side and passenger entertainment side, embedded computers and power supplies play critical roles. Railway systems need sophisticated networking, data collection and real-time control, all while meeting safety standards. Circuit Cellar Chief Editor Jeff Child looks at the latest technology trends and products relevant to railway applications.

Product Focus:
IoT Interface Modules
The fast growing IoT phenomenon is driving demand for highly integrated modules designed for the IoT edge. Feeding those needs, a new crop of IoT modules have emerged that offer pre-certified solutions that are ready to use. This Product Focus section updates readers on this technology trend and provides a product album of representative IoT modules.

TECHNOLOGIES AND TECHNIQUES FOR ENGINEERS

FPGA Signal Processing
Offering the dual benefits of powerful signal processing and system-level integration, FPGAs have become a key technology for embedded system developers. Makers of chip and board-level FPGA products are providing complete solutions to enable developers to meet their application needs. Circuit Cellar Chief Editor Jeff Child explores the latest technology trends and product developments in FPGA signal processing.

Macros for AVR Assembler Programming
The AVR microcontroller instruction set provides a simplicity that makes it good for learning the root principles of machine programming. There’s also a rich set of macros available for the AVR that ease assembler-level programming. In this article, Wolfgang Matthes steps you through these principles, with the goal of helping programmers “think low-level, write high-level” when they approach embedded systems software development.

Inrush Current Limiters in Action
At the moment a high-power system is switched on, high loads can result in serious damage—even when the extra load is only for short time. Inrush current limiters (ICLs) can help prevent these issues. In this article, TDK Electronics’ Matt Reynolds examines ICLs based on NTC and PTC thermistors, discussing the underlying technology and the device options.

A Look at Cores with TrustZone-M
It’s not so easy to keep up with all the new security features on the latest and greatest embedded processors—especially while you’re busy focusing on the more fundamental and unique aspects of your design. In this article, Colin O’Flynn helps out by examining the new processor cores using TrustZone-M, a feature that helps you secure even low-cost and lower power system designs.

PROJECTS THAT REUSE & RECYCLE

Energy Monitoring Part 2
In Part 1 of this article series, George Novacek began describing an MCU-based system he built to monitor his household energy. Here, he continues that discussion, this time focusing on the electrical power tracking module. As the story shows, he stuck to a design challenge of building the system with as many components he already had in his component bins.

Variable Frequency Drive Part 1
Modern appliances claim to be more efficient, but they’re certainly not designed to last as long as older models. In this project article, Brian Millier describes how he reused subsystems from a defunct modern washing machine to power his bandsaw. The effort provides valuable insights on how to make use of the complete 3-phase Variable Frequency Drive (VFD) borrowed from the washing machine.

FUN PROJECT ARTICLES WITH ALL THE DETAILS

Windless Wind Chimes (Part 2)
In part 1 of this article series, Jeff Bachiochi built a system to simulate breezes randomly playing the sounds of suspended wind chimes. In part 2 the effort evolves into a less random, more orchestrated project. Jeff decided this time to craft a string of chromatically tuned chimes, similar to what an orchestra might use so the project could be used to play music. The project relies on MIDI, an industry standard music technology protocol designed to create and share music and artistic works.

Building a Smart Frying Pan
There’s almost no limit to what an MCU can be used for—-including objects that previously had no electronics at all. In this article, learn how Cornell University graduate Joseph Dwyer build a Microchip PIC32 MCU-based system that wirelessly measures and controls the temperature of a pan on a stove. The system improves both the safety and reliability of cooking on the stove, and has potentially interesting commercial applications.

EOG-Controlled Video Game
There’s much be to learned about how electronics can interact with biological signals—not only to record, but also to see how they can be used as inputs for control applications. With ongoing research in fields such as virtual reality and prosthetics, new systems are being developed to interpret different types of signals for practical applications. Learn how Cornell graduates  Eric Cole, Evan Mok and Alex Huang use electrooculography (EOG) to control a simple video game by measuring eye movement.

Catalog of 125 Open-Spec Hacker Boards: Spring 2019 Edition!

Circuit Cellar’s sister website Linuxgizmos,com has posted its annual Spring edition catalog of hacker-friendly, open-spec SBCs that run Linux or Android.

The catalog includes summaries of 125 community-backed Linux/Android hacker boards under $200 are listed in alpha order.

They list specs and lowest available pricing recorded in the last two weeks of May 2019, with products either shipping or available for pre-order with expected ship date by the end of June.

CHECK IT OUT HERE!

June Circuit Cellar: Sneak Preview

The June issue of Circuit Cellar magazine is out next week!. We’ve been tending our technology crops to bring you a rich harvest of in-depth embedded electronics articles. We’ll have this 84-page magazine brought to your table very soon..

Not a Circuit Cellar subscriber?  Don’t be left out! Sign up today:

 

Here’s a sneak preview of June 2019 Circuit Cellar:

TOOLS AND CONCEPTS FOR ENGINEERS

Integrated PCB Design Tools
After decades of evolving their PCB design tool software packages, the leading tool vendors have the basics of PCB design nailed down. In recent years, these companies have continued to come up with new enhancements to their tool suites, addressing a myriad of issues related to not just the PCB design itself, but the whole process surrounding it. Circuit Cellar Chief Editor Jeff Child looks at the latest integrated PCB design tool solutions.

dB for Dummies: Decibels Demystified
Understanding decibels—or dB for short—may seem intimidating. Frequent readers of this column know that Robert uses dB terms quite often—particularly when talking about wireless systems or filters. In this article, Robert Lacoste discusses the math underlying decibels using basic concepts. The article also covers how they are used to express values in electronics and even includes a quiz to help you hone your decibel expertise.

Understanding PID
As a means for implementing feedback control systems, PID is an important concept in electronics engineering. In this article, Stuart Ball explains how PID can be applied and explains the concept by focusing on a simple circuit design.

DESIGNING CONNECTED SYSTEMS

Sensor Connectivity Trends
While sensors have always played a key role in embedded systems, the exploding Internet of Things (IoT) phenomenon has pushed sensor technology to the forefront. Any IoT implementation depends on an array of sensors that relay input back to the cloud. Circuit Cellar Chief Editor Jeff Child dives into the latest technology trends and product developments in sensors with an emphasis on their connectivity aspects.

Bluetooth Mesh (Part 3)
In this next part of his article series on Bluetooth mesh, Bob Japenga looks at how to create secure provisioning for a Bluetooth Mesh network without requiring user intervention. He takes a special look at an attack which Bluetooth’s asymmetric key encryption is vulnerable to called Man-in-the-Middle.

PONDERING POWER AND ENERGY

Product Focus: AC-DC Converters
To their peril, embedded system developers often treat their choice of power supply as an afterthought. But choosing the right AC-DC converter is critical to the ensuring your system delivers power efficiently to all parts of your system. This Product Focus section updates readers on these trends and provides a product album of representative AC-DC converter products.

Energy Monitoring (Part 1)
The efficient use of energy is a topic moving ever more front and center these days as climate change and energy costs begin to affect our daily lives. Curious to discover how efficient his own energy consumption was, George Novacek built an MCU-based system to monitor his household energy. And, in order to make sure this new device wasn’t adding more energy use, he chose to make the energy monitoring system solar-powered.

Building a PoE Power Subsystem
Power-over-Ethernet (PoE) allows a single cable to provide both data interconnection and power to devices. In this article, Maxim Integrated’s  and Maxim Integrated’s Thong Huynh and Suhei Dhanani explore the key issues involved in implementing rugged PoE systems. Topics covered include standards compliance, interface controller selection, DC-DC converter choices and more.

Taming Your Wind Turbine
While you can buy off-the-shelf wind power generators these days, they tend to get bad reviews from users. The problem is that harnessing wind energy takes some “taming” of the downstream electronics. In this article, Alexander Pozhitkov discusses his characterization project for a small wind turbine. This provides a guide for designing your own wind energy harvesting system.

MORE PROJECT ARTICLES WITH ALL THE DETAILS

Windless Wind Chimes (Part 1)
Wind chimes make a pleasant sound during the warm months when windows are open. But wouldn’t it be nice to simulate those sounds during the winter months when your windows are shut? In part 1 of this project article, Jeff Bachiochi builds a device that simulates a breeze randomly playing suspended wind chimes. Limited to the standard 5-note pentatonic chimes, this device is based on a Microchip PIC18 low power microcontroller.

GPS Guides Robotic Car
In this project article, Raul Alvarez-Torrico builds a robotic car that navigates to a series of GPS waypoints. Using the Arduino UNO for a controller, the design is aimed at robotics beginners that want to step things up a notch. In the article, Raul discusses the math, programing and electronics hardware choices that went into this project design.

Haptic Feedback Electronic Travel Aid
Time-of-flight sensors have become small and affordable in the last couple years. In this article, learn how Cornell graduates Aaheli Chattopadhyay, Naomi Hess and Jun Ko detail creating a travel aid for the visually impaired with a few time-of-flight sensors, coin vibration motors, an Arduino Pro Mini, a Microchip PIC32 MCU, a flashlight and a sock.

Whiskey-Lake U Processor Rides COM Express Type 6 Module

TQ Systems has released a COM Express Compact Type 6 module TQMx80UC based on the 8th generation Intel Core Mobile Processors code named “Whiskey-Lake U”. This module is well suited for industrial controllers, robotics applications, medical devices and point-of-sales. Depending on the required functionality and computing power, several CPU variants (i7, i5, i3, Pentium, Celeron) with two or four cores can be selected. With a thermal power loss of 15 W TDP, four cores are now available for the first time in this performance class (previously two for the 7th generation U series).

The memory interface is equipped with the fast DDR4-2400 technology. The memory capacity can be selected between 4 GB and 64 GB depending on the SO-DIMM modules used. Up to nine PCI Express lanes (Gen3; 8 GHz) are available for connecting up to five peripheral devices and can be flexibly configured in the BIOS. For the first time, the new USB 3.1 Gen2 standard is supported, which allows transfer rates of up to 10 Gbit/s.

Four high-speed interfaces are available for this purpose. In addition, eMMC flash in sizes between 8 GB and 128 GB is available for the first time on the module. The COM Express Compact Module TQMx80UC with its dimensions of 95 mm x 95 mm and Type 6 pinout conforms to PICMG COM.0 R3.0. It is supported by the new TQ mainboard MB-COME6-3. Together with a 11 mm high heatspreader and a heatsink, the combination of boards results in an effective evaluation platform.

TQ Systems | www.tq-group.com

 

 

PIC MCU Development Board for Cloud IoT Core

Microchip Technology has announced an IoT rapid development board for Google Cloud IoT Core that combines a low-power PIC MCU, CryptoAuthentication secure element IC and fully certified Wi-Fi network controller. The solution provides a simple way to connect and secure PIC MCU-based applications. It’s designed to remove the added time, cost and security vulnerabilities that come with large software frameworks and RTOS.
As part of Microchip’s extended partnership with Google Cloud, the PIC-IoT WG Development Board enables PIC MCU designers to easily add cloud connectivity to next-generation products using a free online portal at www.PIC-IoT.com. Once connected, developers can use Microchip’s MPLAB Code Configurator (MCC) rapid development tool to develop, debug and customize their application.

The board includes:

  • eXtreme Low-Power (XLP) PICMCU with integrated Core Independent Peripherals: Well suited for battery-operated, real-time sensing and control applications, the PIC24FJ128GA705 MCU provides the simplicity of the PIC architecture with added memory and advanced analog integration. With the latest Core Independent Peripherals (CIPs) designed to handle complex applications with less code and decreased power consumption, the device provides the ideal combination of performance with extremely low power consumption.
  • Secure element to protect the root of trust in hardware: The ATECC608A CryptoAuthentication device provides a trusted and protected identity for each device that can be securely authenticated. ATECC608A devices come pre-registered on Google Cloud IoT Core and are ready for use with zero-touch provisioning.
  • Wi-Fi connectivity to Google Cloud: The ATWINC1510 is an industrial-grade, fully certified IEEE 802.11 b/g/n IoT network controller that provides an easy connection to an MCU of choice via a flexible SPI interface. The module relieves designers from needing expertise in networking protocols.

Google Cloud IoT Core provides a fully managed service that enables designers to easily and securely connect, manage and ingest data from devices at a global scale. The platform collects, processes and analyzes data in real time to enable designers to improve operational efficiency in embedded designs.

The PIC-IoT WG development board is supported by the MPLAB X Integrated Development Environment (IDE) and MCC rapid prototyping tool. The board is compatible with more than 450 MikroElektronika Click boards that expand sensors and actuator options. Developers who purchase the kit will have access to an online portal for immediate visualization of their sensors’ data being published. Supported by complete board schematics and demo code, the PIC-IoT WG development board helps get customers to market quickly with differentiated IoT end products.

The PIC-IoT WG Development Board (AC164164) is available in volume production now for $29 each.

Microchip Technology | www.microchip.com

Catalog of 122 Open-Spec Linux Hacker Boards

Circuit Cellar’s sister website Linuxgizmos,com has posted its 2019 New Year’s edition catalog of hacker-friendly, open-spec SBCs that run Linux or Android. The catalog provides recently updated descriptions, specs, pricing, and links to details for all 122 SBCs.

CHECK IT OUT HERE!

Tiny MCU-Based Development Platform Hosts Dual USB Ports

Segger Microcontroller has introduced emPower-USB-Host, a compact low-cost development board. With two USB host ports, many applications using USB peripherals can be realized with little effort. Precompiled applications for barcode and smartcard readers, as well as POS displays, LTE sticks and USB to LAN adapters are available for download, including complete projects for Embedded Studio with source code of these applications. The applications are using Segger’s emUSB-Host software API, which makes accessing the different types of USB devices easy.
emPower-USB-Host uses the emLoad bootloader, pre-loaded into the flash of the MCU, to easily change applications in seconds using a USB flash drive. Development of custom applications is also supported. The board has a debug connector, providing full access to the NXP LPC54605J512 MCU with its Cortex-M4 core. Schematics and PCB layout of the board are available under a Creative Commons license. This way, the hardware can be used as a blueprint for custom devices using two USB host ports.

Segger Microcontroller | www.segger.com

Signature Analyzer Uses NXP MCU

Scope-Free Tester

Doing a signature analysis of a signal used to require an oscilloscope to display your results. In this article, Brian details how to build a free-standing tester using mostly just the internal peripherals of an NXP Arm microcontroller. He describes how the tester operates and how he implemented it.

By Brian Millier

When I was a teenager starting out in electronics, I longed to have as much test equipment as possible. At that stage in life, I couldn’t afford much beyond a multimeter. I remember seeing plans for a component tester in an electronics magazine. There weren’t many hobby electronics magazines back in the ‘60s, so it was probably Popular Electronics. This tester would provide a “signature” of most passive/active components by placing a small AC voltage across the component and measuring the resulting current. My memory of the circuit is hazy after all these years, but it was trivial: a 6.3 V filament transformer, a current sensing resistor and a few other passive components. However, the catch was that it required an oscilloscope to display the resulting voltage vs. current plot—in other words, the component’s signature. By the time I bought an oscilloscope about 10 years later, I had completely forgotten about this testing concept.

Today, test instruments are available that include a dedicated graphics display, instead of relying on an oscilloscope for display purposes. Having worked with Arm microcontrollers over the last few years,
I realized that I could implement such a free-standing tester using, in large part, just the internal MCU peripherals.

In this article I’ll describe how the tester operates, and how I implemented it using a Teensy 3.5 development module (containing an NXP MK64FX512VMD12 MCU) and featuring a FT800-based intelligent 4.3″ TFT touch-screen display.

Basic Theory of Operation

To obtain a signature of a given component, you need to place a variable voltage across it and measure the resulting current through it, at each voltage level. In many cases, the component’s normal operating mode will include both positive and negative voltages across it, so the tester must provide an AC voltage source. For most testing purposes you would use a sine wave voltage source because most AC calculations are done using sine waves. The value of this AC voltage source must be adjustable. I decided on six ranges between 0.5 V peak-peak and 20 V peak-peak. For measuring the voltage across the component, I used an instrumentation amplifier with three hardware gain ranges—plus three additional ranges based upon scaling in software.

To monitor current, it’s easiest to measure the voltage across a small value resistor placed in the ground return path, and then convert that to current using Ohm’s Law. Here too you need a range of current measurements. I chose to provide three hardware ranges—plus four additional ranges based on software scaling—between 1 mA and 100 mA.

You can’t just place an AC voltage of any given value across a component, and hope that the component will be able to handle that current without damage. You must place a resistor in series with the component to limit the current flow. That resistor may need to vary in value over several decades, depending on the component being tested. In my tester, I provide a switchable resistor bank with values covering a 1,000:1 range in decade steps.

Figure 1 is a block diagram of the basic tester circuitry. The user interface, touch-screen display and SD card data storage are not shown here. The MK64FX512VMD12 MCU’s 12-bit DAC A provides a sine wave signal that varies between 0 and 1.2 V over the full AC cycle. The programmable attenuator is an SPI pot device with 12-bit resolution. C1 is a decoupling capacitor, which shifts the (attenuated) unipolar DAC A output signal into a bipolar AC signal. This AC signal is amplified by a factor of 21 by an LM675 power amplifier IC. DAC B, along with some passive components, provide a software-adjustable offset voltage adjustment. The LM675 amplifier is needed to provide enough drive current to handle the higher current ranges—up to 100 mA.

FIGURE 1
This is a block diagram of the AC signal generation and Voltage/Current monitoring circuit.

Both the voltage and current are monitored using Texas Instruments (TI)instrumentation amplifier ICs. These contain input protection circuitry good to ±40 V. The various gains needed for both amplifiers are set by 1% resistors, which are switched by miniature reed relays. The instrumentation amplifier output voltages, representing voltage and current through the component under test, are fed to the two 16-bit ADCs present in the NXP MK64FX512VMD12 Arm MCU. The sine wave signal generated by the MCU can be set for frequencies of 20, 50 ,60, 100, 200 or 400 Hz.

Signature Analysis

The basic premise of signature analysis is that you obtain a signature of a component that is of questionable condition, and then compare it with a known-good component of the same value. Alternately, you can do the same comparison on a specific circuit node on two identical circuit boards/assemblies.. …

Read the full article in the August 337 issue of Circuit Cellar

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Note: We’ve made the October 2017 issue of Circuit Cellar available as a free sample issue. In it, you’ll find a rich variety of the kinds of articles and information that exemplify a typical issue of the current magazine.

The Voting Results are in. We Have a Winner!

Circuit Cellar’s sister website LinuxGizmos.com has completed its 2018 hacker board survey, which ran on SurveyMonkey in partnership with Linux.com. Survey participants chose the new Raspberry Pi 3 Model B+, as the favorite board from among 116 community-backed SBCs that run Linux or Android and sell for under $200.
All 116 SBCs are summarized in LinuxGizmos’ recently updated hacker board catalog and feature comparison spreadsheet.

GO HERE TO READ THE SURVEY RESULTS WITH ANALYSIS

Deadline Extended to June 22 — Vote Now!

UPDATE: We’ve extended our 2018 reader survey on open-spec Linux/Android hacker boards through this Friday, June 22.   Vote now!

Circuit Cellar’s sister website LinuxGizmos.com has launched its fourth annual reader survey of open-spec, Linux- or Android-ready single board computers priced under $200. In coordination with Linux.com, LinuxGizmos has identified 116 SBCs that fit its requirements, up from 98 boards in its June 2017 survey.

Vote for your favorites from LG’s freshly updated catalog of 116 sub-$200, hacker-friendly SBCs that run Linux or Android, and you could win one of 15 prizes.

Check out LinuxGizmos’ freshly updated summaries of 116 SBCs, as well as its spreadsheet that compares key features of all the boards.

Explore this great collection of Linux SBC information. To find out how to participate in the survey–and be entered to win a free board–click here:

GO HERE TO TAKE THE SURVEY AND VOTE

 

 

Target Boards for Renesas RX 32-bit MCUs

Renesas Electronics has announced three new Target Boards for the RX65N, RX130 and RX231 Microcontroller (MCU) Groups, each designed to help engineers jump start their home appliance, building and industrial automation designs. Priced below $30, the Target Boards lower the price threshold for engagement, allowing more system developers to make use of Renesas’ broad-based 32-bit RX MCU family.

The RX Target Boards provide an inexpensive entry point for embedded designers to evaluate, prototype and develop their products. Each board kit features an on-chip debugger tool that enables application design without requiring further tool investments. Through-hole pin headers provide access to all MCU signals pins, making it easy for users to interconnect to standard breadboards for fast prototyping.

The RX Target Board evaluation concept reuses the same PCB for all MCU variations. Since each member of the Renesas RX MCU Family has a common pin assignment, users experience a smooth transition between different RX Groups and RX Series using the same package version. In the case of the RX Target Boards, the widely used 100-pin LQFP package is on board.

The RX Target Boards offer everything designers need to start board and demo development, including a board circuit diagram and bill of materials, demo source code, user manual, and application notes. Additional Target Board variations will be released soon that will provide full coverage of the entire RX Family, from the low-power RX100 Series to the high-performance RX700 Series.

The RX65N MCU Group combines an enhanced RX CPU core architecture and 120 MHz operation to achieve processing performance of 4.34 CoreMark/MHz. The MCUs include an integrated Trusted Secure IP, enhanced, trusted flash functionality, and a human-machine interface (HMI) for industrial and network control systems operating at the edge of the Industrial Internet of Things (IIoT). The RX65N MCUs also include an embedded TFT controller and integrated 2D graphic accelerator with advanced features ideal for TFT displays designed into IIoT edge devices or system control applications. In addition, the RX65N MCUs include embedded communication-processing peripherals such as Ethernet, USB, CAN, SD host/slave interface and quad SPI.

The RX130 MCU Group provides 32 MHz operation with flash memory sizes up to 512 KB, and package sizes up to 100-pins to provide higher performance and compatibility with the RX231/RX230 Group of touch MCUs. The ultra-low power, low-cost RX130 Group adds higher responsiveness and functionality for touch-based applications requiring 3V or 5V system control and low power consumption. Featuring a new capacitive touch IP with improved sensitivity and robustness, and a comprehensive device evaluation environment, the new 32-bit RX130 MCUs are an ideal fit for devices designed with challenging, non-traditional touch materials, or required to operate in wet or dirty environments, such as a kitchen, bath or factory floor.

The RX Target Boards are available now through Renesas Electronics’ worldwide distributors with a recommended resale price below $30.

Renesas Electronics | www.renesas.com