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Building a Generator Control System

Three-Phase Power

Three-phase electrical power is a critical technology for heavy machinery. Learn how these two US Coast Guard Academy students built a physical generator set model capable of producing three-phase electricity. The article steps through the power sensors, master controller and DC-DC conversion design choices they faced with this project.
(Caption for lead image: From left to right: Aaron Dahlen, Caleb Stewart, Kent Altobelli and Christopher Gosvener.).

By Kent Altobelli and Caleb Stewart

Three-phase electrical power is typically used by heavy machinery due to its constant power transfer, and is used on board US Coast Guard cutters to power shipboard systems while at sea. In most applications, electrical power is generated by using a prime mover such as a diesel engine, steam turbine or water turbine to drive the shaft of a synchronous generator mechanically. The generator converts mechanical power to electrical power by using a field coil (electromagnet) on its spinning rotor to induce a changing current in its stationary stator coils. The flow of electrons in the stator coils is then distributed by conductors to energize various systems, such as lights, computers or pumps. If more electrical power is required by the facility, more mechanical power is needed to drive the generator, so more fuel, steam or water is fed to the prime mover. Together, the prime mover and the generator are referred to as a generator set “genset”.

Because the load expects a specific voltage and frequency for normal operation, the genset must regulate its output using a combination of its throttle setting and rotor field strength. When a real load, such as a light bulb, is switched on, it consumes more real power from the electrical distribution bus, and the load physically slows down the genset, reducing the output frequency and voltage. The shaft rotational speed determines the number of times per second the rotor’s magnetic field sweeps past the stator coils, and determines the frequency of the sinusoidal output. Increasing the throttle returns the frequency and voltage to their setpoints.

When a partially reactive load—for example, an induction motor—is switched on, it consumes real power, but also adds a complex component called “reactive power.” This causes a voltage change due to the way a generator produces the demanded phase offset between supplied voltage and current. An inductive load, common in industrial settings, causes the voltage output to sag, whereas a capacitive load causes the voltage to rise. Voltage induced in the stator is controlled by changing the strength of the rotor’s electromagnetic field that sweeps past the stator coils in accordance with Faraday’s Law of inductance. Increasing the voltage supply to the rotor’s electromagnet increases the magnetic field and brings the voltage back up to its setpoint.

The objective of our project was to build a physical generator set model capable of producing three-phase electricity, and maintain each “Y”-connected phase at an output voltage of 120 ±5 V RMS (AC) and frequency of 60 ±0.5 Hz. When the load on the system changes, provided the system is not pushed beyond its operating limits, the control system should be capable of returning the output to the acceptable voltage and frequency ranges within 3 seconds. When controlling multiple gensets paralleled in island operation, the distributed system should be able to meet the same voltage and frequency requirements, while simultaneously balancing the real and reactive power from all online gensets.

Two Configurations

Gensets supply power in two conceptually different configurations: “island” operation with stand-alone or paralleled (electrically connected) gensets, or gensets paralleled to an “infinite” bus.” In island operation, the entire electrical bus is relatively small—either one genset or a small number of total gensets—so any changes made by one genset directly affects the voltage and frequency of the electrical bus. When paralleled to an infinite bus such as the power grid, the bus is too powerful for a single genset to change the voltage or frequency. Coast Guard cutters use gensets in island operation, so that is the focus of this article.

When in island operation, deciding how much to compensate for a voltage or frequency change is accomplished using either droop or isochronous (iso) control. Droop control uses a proportional response to reduce error between the genset output and the desired setpoint. For example, if the frequency of the output drops, then the throttle of the prime mover is opened correspondingly to generate more power and raise the frequency back up. Since a proportional response cannot ever achieve the setpoint when loaded (a certain amount of constant error is required to keep the throttle open), the output frequency tends to decrease linearly with an increase in power output. A no-load to full-load droop of 2.4 Hz is typical for a generator in the United States, but this can usually be adjusted by the user.

Frequency control typically uses a mechanical governor to provide the proportional throttle response to meet real power demand. Voltage control typically uses an automatic voltage regulator (AVR) to manipulate the field coil strength to meet reactive power demand. Isochronous mode is more challenging, because it always works to return the genset output to the setpoint. Maintaining zero error on the output usually requires some combination of a proportional response to compensate for load fluctuation quickly, and also a long-term fine-tuning compensation to ensure the steady-state output achieves the setpoint.

If two or more gensets are paralleled, the combined load is supplied by the combined power output of the gensets. As before, maintaining the expected operating voltage and frequency is the first priority, but with multiple gensets, careful changes to the throttle and field can also redistribute the real and reactive power to meet real and reactive power demand efficiently.

If the average throttle or field setting is increased, then the overall bus frequency or voltage, respectively, also increases. If the average throttle or field setting stays the same while two gensets adjust their settings in opposite directions, the frequency or voltage stay the same, but the genset that increased their throttle or field provides a greater portion of the real or reactive power. Redistribution is important because it allows gensets to produce real power at peak efficiency and share reactive power evenly, because excessive reactive power generation derates the generator. Reactive currents flowing through the windings cause heat without producing real, useful power.

Four Conditions

Before the breaker can be closed to parallel generators, four conditions need to be met between the oncoming generators and the bus to ensure smooth load transfer:

1) The oncoming generator should have the same or a slightly higher voltage than the bus.
2) The oncoming generator should have the same or a slightly higher frequency than the bus.
3) The phase angles need to match. For example, the oncoming generator “A” phase needs to be at 0 degrees when the bus “A” phase is at 0 degrees.
4) The phase sequences need to be the same. For example, A-B-C for the oncoming generator needs to match the A-B-C phase sequence of the bus.

Meeting these conditions can be visualized using Figure 1, which shows a time vs. voltage representation of an arbitrary, balanced three-phase signal. The bus and the generator each have their own corresponding plots resembling Figure 1, and the two should only be electrically connected if both plots line up and therefore satisfy the four conditions listed above.

Figure 1
Arbitrary three phase sinusoid

If done properly, closing the breaker will be anticlimactic, and the gensets will happily find a new equilibrium. The gensets should be adjusted immediately to ensure the load is split evenly between gensets. If there is an electrical mismatch, the generator will instantly attempt to align its electrical phase with the bus, bringing the prime mover along for a wild ride and potentially causing physical damage—in addition to making a loud BANG! Idaho National Laboratories demonstrated the physical damage caused by electrical mismatch in its 2007 Aurora Generator Test.

Three primary setups for parallel genset operation are discussed here: droop-droop, isochronous-droop, and isochronous-isochronous. The simplest mode of parallel operation between two or more gensets is a droop-droop mode, where both gensets are in droop mode and collectively find a new equilibrium frequency and voltage according to the real and reactive power demands of the load.

Isochronous-droop (iso-droop) mode is slightly more complex, where one genset is in droop mode and the other is in iso mode. The iso genset always provides the power required to maintain a specific voltage and frequency, and the droop genset produces a constant real power corresponding to that one point on its droop curve. Because the iso genset works more or less depending on the load, it is also termed the “swing” generator.

Finally, isochronous-isochronous (iso-iso) is the most complex. In iso-iso mode, both gensets attempt to maintain the specified output voltage and frequency. While this sounds ideal, this mode has the potential for instability during transient loading, because individual genset control systems may not be able to differentiate between a change in load and a change in the other genset’s power output. Iso-iso mode usually requires direct communication or a higher level controller to monitor both gensets, so they respond to load changes without fighting each other. With no external communication, one genset could end up supplying the majority of the power to the load while the second genset is idling, seeing no need to contribute because the bus voltage and frequency are spot on! At some point one genset could even resist the other genset, consuming real power and causing the generator to “motor” the prime mover. Unchecked, this condition will damage prime movers, so a reverse power relay is usually in place to trip the genset offline, leaving only one genset to supply the entire load.

System Design

Each genset simulated on the Hampden Training Bench had a custom sensor monitoring the generator voltage, current, and frequency output, a small computer running control calculations and a pair of DC-to-DC converters to close the control loop on the generator’s rotational velocity and field strength. The genset was simulated by coupling a 330 W brushed DC motor acting as the prime mover to a four-pole 330 W synchronous generator (Figure 2).

Figure 2
Simulated genset on the Hampden Training Bench

Our power sensor was a custom-designed circuit board with an 8-bit microcontroller (MCU) employed to sample the genset output continuously and provide RMS voltage, RMS current, real power, reactive power, and frequency upon request. The control system ran on a Linux computer with custom software designed to poll the sensor for data, calculate the appropriate control response to return the system to the set point and generate corresponding pulse width modulated (PWM) outputs. Finally, the PWM outputs controlled the DC-to-DC converter to step down the DC supply voltage to drive the prime mover and energize the generator field coil. The component relationships are shown in Figure 3, where the diesel engine in a typical genset was replaced by our DC motor.

Figure 3
Genset component layout

Since this project was a continuation of a previous year of work by Elise Sako and Jasper Campbell, several lessons were learned that required the system be redesigned from the ground up. One of the largest design constraint from the previous year was the decision to use a variable frequency drive (VFD) to drive an induction motor as the prime mover. While this solution is acceptable, it introduces inherent delay in the control loop, because the VFD is designed to execute commands as smoothly but not necessarily as quickly as possible.

Another design constraint was the decision to power the generator field coil using DC regulated by an off-the-shelf silicon controller rectifier (SCR) chopper. Again, while this is an acceptable solution, the system output suffered from the SCR’s slow response time (refresh rate is limited to the AC supply frequency), and voltage output regulation was non-ideal (capacitor voltage refresh again limited by the frequency of the AC supply).

To solve these performance constraints, we selected the responsive and easily controllable DC motor as the prime mover so the DC output from our Hampden Training Bench could be used as the power supply for both the DC motor and the generator field coil. By greatly simplifying the electrical control of the genset, we reduced implementation cost and improved control system response time. …

Read the full article in the February 343 issue of Circuit Cellar
(Full article word count: 6116 words; Figure count: 14 Figures.)

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Cutting-edge Embedded Vision Solutions Are Here

Clarius Mobile Health revolutionized ultrasounds. Xilinx’s technology helped get them there. IoT-connected, portable ultrasound machine leveraged Xilinx’s Zynq programmable SOC solution. Avnet connected Clarius to Xilinx’s technology—some of which wasn’t even on the shelves yet.

120 W and 240 W DIN Rail Power Supplies Boast 93% Efficiency

TDK has announced the introduction of 120 W and 240 W rated models to the DRB series of AC-DC DIN rail mount power supplies. Their narrow width allows additional devices to be installed on the rail, saving cabinet space. The high 93% efficiency produces less internal waste heat enabling electrolytic capacitors to run cooler, extending field operating life to greater than 7 years at 75% load, 230Vac input. Applications include industrial process control, factory automation, semiconductor fabrication and test and measurement equipment.

Rated for continuous operation at 120 W and 240 W, the DRBs can deliver a +20% peak load for up to 10 seconds. The power supplies are currently available with a 24V output, adjustable from 24 V to 28 V, and can accept an 85 to 264 Vac input withstanding surges of up to 300 Vac for 5 seconds. The operating ambient temperature is -25oC to +70oC, -40oC cold start, derating linearly above 55oC to 50% load at 70oC.

In addition to a front panel LED, an isolated DC OK opto-coupled signal is provided to show the output status either locally or remotely. The DRB120 and DRB240 have a rugged metal enclosure measuring 124 mm in height, 125 mm deep and narrow widths of 35 mm and 41 mm respectively.

Input to output isolation is 3,000 Vac, input to ground 1500 Vac and the output to ground is 500Vac. Both models are certified to the safety standards of IEC/UL/CSA/EN 60950-1, IEC/UL/CSA/EN 62368-1, UL508, IEC/EN 62477-1 (OVC III) and are CE marked in accordance to the Low Voltage, EMC and RoHS Directives. The DRBs are compliant to EN55011-B, EN55032-B, CISPR11-B, CISPR22-B, EN61204-3 (Class A) radiated and conducted emissions, EN 61000-3-2 harmonics, IEC 61000-4 immunity and SEMI F47 line dip standards.

TDK Lambda | www.us.tdk-lambda.com


February (issue #343) Circuit Cellar Article Materials

Click here for the Circuit Cellar article code archive

p.6: Build a Self-Correcting LED Clock: MCU-Driven Art, By Eldar Slobodyan and Jason Ben Nathan

[1]  C.U. Bruce Land, “Development Boards,” 6 December 2017. [Online]. Available: http://people.ece.cornell.edu/land/courses/ece4760/PIC32/target_board.html
[2]  Cornell Rapid Prototyping Laboratory [Online]. Available: http://cornellrpl.wixsite.com/cornellrpl
[3] C.U. Bruce Land, “Pixel Strip,” 14 August 2017. [Online]. Available: https://people.ece.cornell.edu/land/courses/ece4760/PIC32/index_pixel_strip.html
[4} C.U. Bruce Land, “Protothreads and Timers,” 31 October 2017. [Online]. Available: http://people.ece.cornell.edu/land/courses/ece4760/PIC32/index_Protothreads.html

Video of the project:

Adafruit, www.adafruit.com
All Electronics | www.allelectronics.com
Digi-Key | www.digikey.com
Microchip Technology | www.microchip.com
Mean Well USA | www.meanwellusa.com
Texas Instruments | www.ti.com

p.14: Inductive Sensing with PSoC MCUs: Tougher Touch Tech, By Nishant Mittal

Cypress Semiconductor’s CY8CKIT-148 PSoC 4700S Inductive Sensing Evaluation Kit

Inductive Sensing Design guide

Cypress Semiconductor | www.cypress.com

Scroll down to the APPENDIX of this page to find a set of MagSense Component screen shots showing the tuning configuration parameters for the buttons and
proximity along with settings for the SCB configured as EZI2C, and the EZI2C settings themselves.

p.22: Building a Generator Control System: Three-Phase Power, By Kent Altobelli and Caleb Stewart

Microchip Technology | www.microchip.com

p.36 Thermal Management in Machine Learning: Beat the Heat, By Tom Gregory

University of Texas at Arlington (UTA) project

6SigmaET | www.6sigmaet.info
Future Facilities | www.futurefacilities.com
Google Cloud | cloud.google.com

p.40: MCUs Serve Up Solutions for Car Infotainment: Dashboard Dazzle, By Jeff Child

Cypress Semiconductor | www.cypress.com
Infineon Technologies | www.infineon.com
Microchip | www.microchip.com
OpenSynergy | www.opensynergy.com
Renesas Electronics America | www.renesas.com
STMicroelectronics | www.st.com

p.46: SWaP Needs Drive Non-Standard SBC Demand: All-In-One Solutions, By Jeff Child

Advantech | www.advantech.com
Garz & Fricke | www.garz-fricke.com
NXElec | www.nxelec.com
Technologic Systems | www.embeddedarm.com
VersaLogic | www.versalogic.com

p.50: PRODUCT FOCUS ADCs and DACs: Resolution and Speed, By Jeff Child

Analog Devices | www.analog.com
Maxim Integrated | www.maximintegrated.com
Texas Instruments | www.ti.com

p.54: EMBEDDED IN THIN SLICES: Bluetooth Mesh (Part 1): Alternatives Compared, By Bob Japenga

[1] https://www.silabs.com/products/wireless/learning-center/mesh-performance
[2] https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.meshsdk.v2.0.1%2Fmd_doc_introduction_basic_concepts.html
[3] This was a specification error which has since been corrected and was corrected in the SDK that we used in April of 2018. See the CERT database at https://www.kb.cert.org/vuls/id/304725

Nordic Semiconductor | www.nordicsemi.com
Silicon Labs | www.silabs.com

p.58: THE CONSUMMATE ENGINEER: Infrared Sensors: Heat Lights the Way, By George Novacek

[1] Temperature Measurement Part 3, George Novacek, Circuit Cellar # 313, August 2016
[2] Fundamental Optics Part 3, George Novacek, Circuit Cellar #307, Feb 2016
[3] PIR lenses http://www.fresnelfactory.com/pir-fresnel-lens-fd08-10005-flat-shape-wide-angle.html
[4] Zilog Z8FS040 http://ixapps.ixys.com/DataSheet/ps0285.pdf
[5] ON Semiconductor NCS36000-D http://www.onsemi.com/pub/Collateral/NCS36000-D.PDF

Texas Instruments | www.ti.com

p.62: THE DARKER SIDE: The Art of Voltage Probing: Scope Savvy, By Robert Lacoste

WaveRunner 610Zi oscilloscope, WaveMaster 813Zi-B, WaveLink D610 probes

P6150 Z0 passive probe,  P6015 high voltage probe

Analog Circuit Design, volume 2
Immersion in the Black Art of Analog Design
Bob Dobkin & Jim Williams, Linear Technology
Elsevier/Newnes, ISBN 978-0-12-397888-2

What’s All This Scope Probe Stuff, Anyhow?
Bob Pease – Texas Instruments & Tektronix

8 Hints for Better Scope Probing, Keysight application note

Analog Devices | www.analog.com
Keysight | www.keysight.com
ROHM Semiconductor | www.rohm.com
Tektronix | www.tekronix.com
Teledyne Lecroy | www.teledynelecroy.com
Texas Instruments | www.ti.com

p.69: FROM THE BENCH: Tinkering with Time: Protocols and Programming, By Jeff Bachiochi


[1} Arduino support for the ESP32

Arduino monochrome graphics support for the SSD1306 (and other display drivers)

Espressif Systems | www.espressif.com
SparkFun | www.sparkfun.com

p.79: The Future of Artificial Intelligence: Intelligent Edge: Is AI Ready to Play a Role?, By Scott Nelson

Digi International | www.digi.com


APPENDIX : Supplemental materials for Nishant Mittal’s article:

The following 4 screen shots show the tuning configuration parameters for the buttons and proximity.

MagSense Component Configuration Button 1


MagSense Component Configuration Button 2

MagSense Component Configuration Button 3

MagSense Component Configuration Proximity

This next screen shot shows the settings for the SCB configured as EZI2C.

EZI2C Setting

This next screen shot shows the settings for the Digital Output Pin components in PSoC Creator. These pins are used to drive the seven feedback LEDs. The settings are the same for all the Digital output pins in this example.

Digital Output Pin Setting

PCB assembly – $1000 in FREE Labor

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Only a limited number of offers are available each day.

Mini PCIe Expansion Card Boasts PCIe/104 OneBank Interface

WinSystems has introduced its PX1-I416 module, which adds Mini PCI Express expansion capability to embedded systems with PCle/104 OneBank expansion. This product is designed to maximize utilization of a host platform while opening up access to myriad COTS I/O modules from a multitude of suppliers. According the company, system designers can add multiple Mini-Card I/O modules to single board computers like WinSystems’ PX1-C415 without the time, costs or risks of developing proprietary designs.

Compatible with PCle/104 OneBank SBCs, the module incorporates dual Mini-PCI Express slots. Up to four PX1-I416 modules can be stacked together, thereby providing support for up to eight separate Mini-Cards. The onboard PCle and USB multiplexer ensures maximum utilization of the host platform’s PCI Express and USB resources on the OneBank expansion interface. Each PX1-I416 expansion module also includes a separate SIM card holder for use with cellular modems.

The PX1-I416 enables product developers to readily include such functionality as additional USB ports, CAN, and other data acquisition modules, saving time and money. Equally important, these modules are built for enduring, consistent performance at operating temperatures of -40ºC to +85ºC.

WinSystems | www.winsystems.com

Free IoT Security Platform Runs on OpenWrt Routers and the Raspberry Pi

By Eric Brown

At the Consumer Electronics Show (CES) in Las Vegas, Minim announced a free spin-off of Minim, its cloud-managed Wi-Fi and security Software as a Service (SaaS) platform. Minim Labs is designed to work with a new open source software agent called Unum that runs on Raspbian and OpenWrt Linux devices. Optimized images are available for the OpenWrt-based Gli.Net GL-B1300 router and Raspberry Pi. The first 50 sign-ups will get the B1300 router for free (see below).

Minim Labs setup screen
(click image to enlarge)
The Minim Labs toolkit “secures and manages all connected devices in the home, such as the Google Home Hub, Sony Smart TV, and FreeRTOS devices,” providing “device fingerprinting, security scans, AI-powered recommendations, router management, analytics, and parental controls,” says Minim. By signing up to a Minim Labs account you receive a MAC address to register an Unum-enabled device.

The GitHub hosted Unum agent runs on the Linux router where it identifies connected devices and securely streams device telemetry to the Minim platform. Users can open a free Minim Labs account to register up to 10 Unum-enabled devices, offering access to Minim WiFi management apps and APIs. Alternately, you can use Unum with your own application server.

The GL-B1300 and Raspberry Pi builds are designed to walk “home network tinkerers” through the process of protecting devices with Unum and Minim Labs. More advanced developers can download a Unum SDK to modify the software for any OpenWrt-based router.

“By open sourcing our agent and giving technologists free access to our platform, we hope to build a global community that’ll contribute valuable product feedback and code,” stated Jeremy Hitchcock, Founder and CEO of Minim.

Gli.Net’s OpenWrt routers

Gli.Net’s GL-B1300 router runs OpenWrt on a quad-core, Cortex-A7 Qualcomm Atheros IPQ4028 SoC clocked to 717 MHz. The SoC is equipped with a DSP, 256MB RAM, 32 MB flash, and dual-band 802.11ac with 2×2 MIMO. The SoC and supports up to 5-port Ethernet routers abd provides Qualcomm TEE, Crypto Engine, and Secure Boot technologies.

GL-B1300 (left) and GL-AR750S
(click images to enlarge)
The GL-B1300 router has dual GbE ports, a WAN port, and a USB 3.0 port. The $89 price includes a 12V adapter and Ethernet cable.

The testimonial quote below says that the GL-AR750S Slate router, which is a CES 2019 Innovation Awards Honoree, will also support Unum and Minim Labs out of the box. The $70 GL-AR750S Slate runs on a MIPS-based, 775MHz Qualcomm QCA9563 processor and is equipped with 128MB RAM, 128MB NAND flash, and a microSD slot.

The Slate router provides 3x GbE ports and dual-band 802.11ac with dual external antennas. Other features include USB 2.0 and micro-USB power ports plus a UART and GPIO. The router supports WireGuard, OpenVPN, and Cloudflare DNS over TLS.

Gli.Net router comparison chart, including GL-B1300 and GL-AR750S
(click image to enlarge)
In addition to its routers, Gli.Net also sells the OpenWrt-on-Atheros/MIPS Domino Core computer-on-module. The Domino Core shipped in a Kickstarter launched Domino.IO IoT kit back in 2015.

“We are glad that Minim is going to launch open-source tools for DIY users and increase awareness of personal Internet security,” stated GL.iNet CTO Dr. Alfie Zhao. “This initiative shows shared value and vision with GL.iNet. We are happy to provide support for Minim tools on our GL-AR750S Slate router and GL-B1300 router, both of which have support to the latest OpenWrt.”

Further information

The free Minim Labs security platform is available for signup now, and the open source Unum agent is available for download. Minim is offering the first 50 Minim Labs signups with a free startup kit containing the GL-B1300 router. More information may be found at the Minim Labs product page.

This article originally appeared on LinuxGizmos.com on January 9.

Minim | www.minim.co


Building Automation LON-IP Standard Earns ANSI/CTA Approval

The Consumer Technology Association(CTA) and LonMark International have announced that the ANSI/CTA-709.7 LON IP is now approved as a new American National Standard (ANS) by the American National Standards Institute (ANSI). The new standard focuses on the interoperability of Internet of Things (IoT) devices and provides a complete model for implementing LON IP device-to-device and device-to-application communication interoperability.
This new standard will provide multiple parties – including users, developers, vendors, integrators and specifiers of open building control systems – a mechanism to develop and deliver a higher level of interoperability using native Ethernet/IP based devices. The new standard describes the complete set of requirements for vendors to develop LON devices with native IP communications, which offers higher speed and better IT integration flexibility. As more building control networks require more data and more IoT application interfaces, this new media type for LON control networks provides all of the benefits and functionality to meet this growing demand.

The ANSI/CTA-709.7 Implementation Guidelines define the application layer requirements for interoperable devices to communicate directly on Ethernet. It defines the addressing requirements for both IPv4 and IPv6. LonMark will offer full interoperability testing of any device utilizing the new channel type. The standard defines all of the timing parameters, configuration, and interface requirements to the full 709.1 protocol stack.

A few years prior the ANSI/CTA-709.6 Application Elements built upon the ANSI/CTA-709.5 Implementation Guidelines by providing a catalog of more than 100 common device profiles, with more than 380 specific implementation options. These profiles define the mandatory and optional design requirements for standard data variables, standard configuration properties, enumeration types and standard interface file requirements. This extensive library of device profiles includes definitions for a broad collection of devices for HVAC, indoor and outdoor (roadway) lighting, security, access, metering, energy management, fire and smoke control, gateways, commercial and industrial I/O, gas detection, generators, room automation, renewable energy, utility, automated food service, semiconductor fabrication, transportation, home appliances and others.

LonMark International | www.lonmark.org


Secure Cellular Router Serves Industrial and Transportation Needs

Digi International has announced the Digi WR54, a rugged, secure, high-performance wireless router for complex mobile and industrial environments. With dual cellular interfaces, Digi WR54 provides immediate carrier failover for near-constant uptime and continuous connectivity, especially as vehicles move throughout a city or for locations with marginal cellular coverage. Together with a hardened milspec-certified design and built-in Digi TrustFence security framework, this LTE-Advanced router is designed specifically to meet the connectivity challenges inherent in multi-location, on-the-move conditions, from rail and public transit to trucking fleets and emergency vehicle applications.

LTE-Advanced technologies with carrier aggregation are pushing theoretical download speeds to 300 Mbps, and the next generation of cellular radios is capable of aggregating three or more channels for capabilities up to 600 Mbps. It’s expected that 5G deployments this year will push the demands for performance and edge computing even further. Digi WR54 provides an LTE-Advanced cellular module built on a platform that supports higher speeds to optimize bandwidth today while also being positioned for the future as network capabilities improve.

Multiple transit system use cases require rugged, reliable, high-speed connectivity solutions to carry mission-critical data and communications. Transit system integrators require connectivity for fleet tracking, logistics, engine and driver performance monitoring, fare collection and video monitoring; rail companies that are building in wayside data capabilities need constant visibility into complex systems; industrial corporations like utility companies need to monitor high-value assets.

The Digi WR54 architecture supports these performance requirements with not just the aforementioned LTE-Advanced cellular module, but four Gigabit Ethernet ports for wired systems and the latest 802.11 ac Wi-Fi which combine to support the needs of any user. Other key features include:

  • Dual-core 880 MHz MIPS processor: designed with this high-speed architecture, the Digi WR54 is future-built with a CPU capable of supporting higher network speeds and capabilities as infrastructure is updated to support them
  • SAE J1455, MILSTD-810G and IP-54 rated: tested and certified to withstand water, dust, heat, vibration and other environmental challenges suitable to transportation and many industrial applications
  • Optional dual-cellular radios for continuous connectivity between carriers: for users that cannot afford downtime, if the primary cellular carrier drops out, the Digi WR54 automatically and immediately switches over to the secondary carrier
  • Digi TrustFence: a device-security framework that simplifies the process of securing connected devices and adapts to new and evolving threats
  • Digi Remote Manager: with this Digi web-based management tool, users can simply manage their devices, receive alerts and monitor the health of their deployed devices

For users looking to add high-speed passenger Wi-Fi to mass transit systems, the recently launched Digi WR64 dual LTE-Advanced cellular and dual 802.11ac Wi-Fi router offers an all-in-one mobile communications solution for secure cellular connectivity between vehicles and a central operations center. It offers a flexible interface design with integrated Wi-Fi for client and access point connectivity along with USB, serial, a four-port wired Ethernet switch, GPS and Bluetooth in order to consolidate multiple transit or industrial applications into a single, consolidated router.

Digi International| www.digi.com

Utility Metering Solution Taps Semtech’s LoRa Technology

Semtech has announced that Lemonbeat, an IoT solution provider, has integated Semtech’s LoRa devices and wireless radio frequency technology (LoRa Technology) into its smart metering solutions for easier reading and collection of utility usage. Lemonbeat’s LoRa-connected smart meters work by utilizing embedded LoRa-based IoT technology to connect the meter to their own purpose-built receiver units.

Using this connectivity, meters send data through multiple floors in bigger buildings or all way in to the street, where network operators conveniently collect the data without having to enter the building. Using the meters’ other radio frequency, Lemonbeat Radio, meters provide customers accurate data on their energy consumption. With a third-party application, individuals can view and analyze this data, and change their habits accordingly.

Semtech’s LoRa devices and wireless radio frequency technology is a widely adopted long-range, low-power solution for IoT that gives telecom companies, IoT application makers and system integrators the feature set necessary to deploy low-cost, interoperable IoT networks, gateways, sensors, module products, and IoT services worldwide. IoT networks based on the LoRaWAN specification have been deployed in over 100 countries and Semtech is a founding member of the LoRa Alliance.

Lemonbeat | www.lemonbeat.com

Semtech | www.semtech.com

Nordic Semi’s BLE SoC Selected for Ultra Low Power IoT Module

Nordic Semiconductor has announced that Nanopower has selected Nordic’s nRF52832 Bluetooth Low Energy (Bluetooth LE) System-on-Chip (SoC) to provide the wireless connectivity for its nP-BLE52 module, designed for developers of IoT applications with highly restricted power budgets.

The nP-BLE52 module employs a proprietary power management IC—integrated alongside Nordic’s nRF52832 Wafer-Level Chip Scale Package (WL-CSP) SoC in a System-in-Package (SiP)—which enables it to cut power to the SoC, putting it in sleep mode, before waking it up a pre-set time and in the same state as before it was put to sleep. In doing so the SoC’s power consumption in sleep mode is reduced to 10 nA, making it well suited for IoT applications where battery life is critical by potentially increasing cell lifespan 10x.

In active mode, the nRF52832 SoC runs normally. The SoC has been engineered to minimize power consumption with features such as the 2.4GHz radio’s 5.5mA peak RX/TX currents and a fully-automatic power management system. Once the Nordic SoC has completed its tasks, it instructs the nP-BLE52 to put it to sleep and wake it up again at the pre-set time. The nP-BLE52 then stores the Nordics SoC’s state variables and waits until the nRF52832 SoC needs to be powered up again. On wake-up, the device uploads the previous state variables, allowing the Nordic SoC to be restored to the same operational state as before the power was cut. The SoC’s start-up is much more rapid than if it was activated from a non-powered mode.

The nP-BLE52 module also features a low power MCU which can be set to handle external sensors and actuators when the Nordic chip is switched off. In this state, the module still monitors sensors and buffer readings and can trigger wake-ups if these readings are above predetermined thresholds, while consuming less than 1 uA. The nP-BLE52 also integrates an embedded inertial measurement unit (IMU).

The module’s power management is controlled through a simple API, whereby the user can predetermine the duration of the Nordic SoC’s sleep mode, set the wake-up time and date parameters, and select pins for other on/off triggers.

The module offers IoT developers several advantages, either extending battery life and/or reducing the size of the battery required to power the application thereby reducing the end-product footprint. Longer battery life also reduces or eliminates battery swaps and enables the developer to better adjust for remaining useful battery life as the battery discharges. The module is suitable for any battery-powered device which is not required to be constantly active, for example asset tracking, remote monitoring, beacons, and some smart-home applications.

The nRF52832 WL-CSP SoC measures just 3.0 mm by 3.2mm while offering all the features of the conventionally-packaged chip. The nRF52832 is a powerful multiprotocol SoC ideally suited for Bluetooth LE and 2.4 GHz ultra low-power wireless applications. It combines an 64 MHz, 32-bit Arm Cortex M4F processor with a 2.4 GHz multiprotocol radio (supporting Bluetooth 5, ANT, and proprietary 2.4 GHz RF software) featuring -96dB RX sensitivity, with 512kB Flash memory and 64kB RAM.

The WL-CSP SoC is supplied with Nordic’s S132 SoftDevice, a Bluetooth 5-certifed RF software protocol stack for building advanced Bluetooth LE applications. The S132 SoftDevice features Central, Peripheral, Broadcaster, and Observer Bluetooth LE roles, supports up to twenty connections, and enables concurrent role operation. Nordic’s unique software architecture provides clear separation between the RF protocol software and the developer’s application code, easing product development.

Nordic Semiconductor | www.nordicsemi.com

Railway DC-DC Converter Pair Feature Integrated Heat Sinks

Aimtec has Introduced the AM20CWR-ZK and AM25EUW-Z railway DC-DC converters. They are 20 W and 25 W devices respectively. The AM20CWR-ZK series offers a a wide input voltage range of 13-176 VDC and an output voltage range from 3.3 V to 15 V. The AM25EUW-Z series offers a 10:1 input voltage range of 16-160 VDC and provides an output voltage range from 5 V to 24 V.

Both series provide an inbuilt heat sink offering wide operating temperature range, from -40°C to 100°C. The devices also feature an isolation of 3,000 VDC for improved reliability and system safety. Furthermore, a higher MTBF of 190,000 hrs., output short circuit protection (OSCP), output over-current protection (OCP) and an output over- voltage protection (OVP) come standard with both series. The AM20CWR-ZK is offered in a 1 x 1 package and the AM25EUW-Z in a 2 x 1 package.

Aimtec | www.aimtec.com


High-Current PC/104 Board Delivers 48 Channels of I/O

Apex Embedded Systems offers the TRACER-DIO-5VIO, a high current PC/104 digital I/O and counter/timer module. The module provides 48-lines of 8255 compatible general purpose I/O and three 16-bit 8254 compatible counter/timers. The board is a COTS module used in military, aerospace and industrial applications.
This product is an update from the company’s classic Tracer-E. The digital I/O module provides true 5 V output swings and accepts full 5 V inputs. It has 48-lines of 8255 compatible general purpose I/O and three 16-bit 8254 compatible counter/timers. Optional 2 mm connectors and cables, terminal board and cable accessories are available. A tin mitigation option available via special order. Firmware modifications are available on request.


  • High-Current Outputs can sink 32 milliamps, and source 32 milliamps per channel. This is true even while operating at high temperatures.
  • Direct Interfacing to OPTO-22’s isolated I/O racks. Digital I/O connector is organized to allow direct connection to OPTO-22’s isolated I/O racks that use the G4 serial of I/O modules, the PB16-H, PB16-J, PB16-K, PB16-L, PB8H and the PB24HQ.
  • Environmental: Wide operating temperature range of -40  to +85 degrees C
  • Polarized connectors prevent incorrect cable installations
  • LED status: an LED displays valid card read/write transactions useful for both product development and field status.
  • Single +5V operation: approximately 500 milliwatts (inputs/outputs unloaded)
  • Out-gassing and fire avoidance: They do not use any tantalum or electrolytic capacitors in any products.
  • Reliability: MTBF of 724,559 hours per MIL-HDBK-217F ground benign at 25o= degrees C.
  • Production: Designed and Assembled in Wisconsin, USA, utilizing an ISO 9001 manufacturing facility.

Apex Embedded Systems | www.apexembeddedsystems.com


February Circuit Cellar: Sneak Preview

The February issue of Circuit Cellar magazine is coming soon. We’ve raised up a bumper crop of in-depth embedded electronics articles just for you, and packed ’em into our 84-page magazine.

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


Electronics for Automotive Infotainment
As automotive dashboard displays get more sophisticated, information and entertainment are merging into so-called infotainment systems. That’s driving a need for powerful MCU- and MPU-based solutions that support the connectivity, computing and interfacing needs particular to these system designs. In this article, Circuit Cellar’s Editor-in-Chief, Jeff Child, looks at the technology and trends feuling automotive infotainment.

Inductive Sensing with PSoC MCUs
Inductive sensing is shaping up to be the next big thing for touch technology. It’s suited for applications involving metal-over-touch situations in automotive, industrial and other similar systems. In his article, Nishant Mittal explores the science and technology of inductive sensing. He then describes a complete system design, along with firmware, for an inductive sensing solution based on Cypress Semiconductor’s PSoC microcontroller.

Build a Self-Correcting LED Clock
In North America, most radio-controlled clocks use WWVB’s transmissions to set the correct time. WWVB is a Colorado-based time signal radio station near. Learn how Cornell graduates Eldar Slobodyan and Jason Ben Nathan designed and built a prototype of a Digital WWVB Clock. The project’s main components include a Microchip PIC32 MCU, an external oscillator and a display.


Product Focus: ADCs and DACs
Analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) are two of the key IC components that enable digital systems to interact with the real world. Makers of analog ICs are constantly evolving their DAC and ADC chips pushing the barriers of resolution and speeds. This new Product Focus section updates readers on this technology and provides a product album of representative ADC and DAC products.

Building a Generator Control System
Three phase electrical power is a critical technology for heavy machinery. Learn how US Coast Guard Academy students Kent Altobelli and Caleb Stewart built a physical generator set model capable of producing three phase electricity. The article steps through the power sensors, master controller and DC-DC conversion design choices they faced with this project.


Non-Standard Single Board Computers
Although standard-form factor embedded computers provide a lot of value, many applications demand that form take priority over function. That’s where non-standard boards shine. The majority of non-standard boards tend to be extremely compact, and well suited for size-constrained system designs. Circuit Cellar Chief Editor Jeff Child explores the latest technology trends and product developments in non-standard SBCs.

Thermal Management in machine learning
Artificial intelligence and machine learning continue to move toward center stage. But the powerful processing they require is tied to high power dissipation that results in a lot of heat to manage. In his article, Tom Gregory from 6SigmaET explores the alternatives available today with a special look at cooling Google’s Tensor Processor Unit 3.0 (TPUv3) which was designed with machine learning in mind.


Bluetooth Mesh (Part 1)
Wireless mesh networks are being widely deployed in a wide variety of settings. In this article, Bob Japenga begins his series on Bluetooth mesh. He starts with defining what a mesh network is, then looks at two alternatives available to you as embedded systems designers.

Implementing Time Technology
Many embedded systems need to make use of synchronized time information. In this article, Jeff Bachiochi explores the history of time measurement and how it’s led to NTP and other modern technologies for coordinating universal date and time. Using Arduino and the Espressif System’s ESP32, Jeff then goes through the steps needed to enable your embedded system to request, retrieve and display the synchronized date and time to a display.

Infrared Sensors
Infrared sensing technology has broad application ranging from motion detection in security systems to proximity switches in consumer devices. In this article, George Novacek looks at the science, technology and circuitry of infrared sensors. He also discusses the various types of infrared sensing technologies and how to use them.

The Art of Voltage Probing
Using the right tool for the right job is a basic tenant of electronics engineering. In this article, Robert Lacoste explores one of the most common tools on an engineer’s bench: oscilloscope probes, and in particular the voltage measurement probe. He looks and the different types of voltage probes as well as the techniques to use them effectively and safely.

Tuesday’s Newsletter: IoT Tech Focus

Coming to your inbox tomorrow: Circuit Cellar’s IoT Technology Focus newsletter. Tomorrow’s newsletter covers what’s happening with Internet-of-Things (IoT) technology–-from devices to gateway networks to cloud architectures. This newsletter tackles news and trends about the products and technologies needed to build IoT implementations and devices.

Bonus: We’ve added Drawings for Free Stuff to our weekly newsletters. Make sure you’ve subscribed to the newsletter so you can participate.

Already a Circuit Cellar Newsletter subscriber? Great!
You’ll get your IoT Technology Focus newsletter issue tomorrow.

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

Our weekly Circuit Cellar Newsletter will switch its theme each week, so look for these in upcoming weeks:

Embedded Boards.(1/22) The focus here is on both standard and non-standard embedded computer boards that ease prototyping efforts and let you smoothly scale up to production volumes.

January has a 5th Tuesday, so we’re bringing you a bonus newsletter:
ICs for Consumer Electronics (1/28)  Today’;s consumer electronic product designs demand ICs that enable low-power, high-functionality and cutthroat costs. Today’;s microcontroller, analog IC and power chip vendors are laser-focused on this lucrative, high-stakes market. This newsletter looks at the latest technology trends and product developments in for consumer electronics ICs

Analog & Power. (2/5) This newsletter content zeros in on the latest developments in analog and power technologies including DC-DC converters, AD-DC converters, power supplies, op amps, batteries and more.

Microcontroller Watch (2/12) This newsletter keeps you up-to-date on latest microcontroller news. In this section, we examine the microcontrollers along with their associated tools and support products.