About Circuit Cellar Staff

Circuit Cellar's editorial team comprises professional engineers, technical editors, and digital media specialists. You can reach the Editorial Department at editorial@circuitcellar.com, @circuitcellar, and facebook.com/circuitcellar

September Circuit Cellar: A Sneak Preview

The September (326) issue of Circuit Cellar magazine serves up a meaty selection of useful technology resources along with inspiring, interesting embedded electronics design articles.

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Here’s a sneak preview of September Circuit Cellar:


Getting Started with PSoC Microcontrollers (Part 3): Data Conversion, Capacitive Sensing and More
In Part 3, Nishant Mittal gets into some if the PSoC’s more complex features like Data Conversion.

Implementing a Time-Oriented Task Manager for 8-bit PIC Microcontrollers
Pedro Bertoleti shows readers how to build a time-oriented task manager using Microchip’s PIC 16F628A 8-bit microcontroller.


Microcontrollers Beef Up Security Features: Defense in a Connected World
Jeff Child explores the various flavors of embedded security features that microcontroller vendors are adding to their devices.

Resources for Embedded Security: Hardware, Software and Services
Circuit Cellar collects four pages worth of info about companies that provide embedded security products, tools and services.


Using Power Audio Amplifiers in Untypical Ways (Part 1): Best Building Blocks
Petre Petrov shows readers how to use PAAs as universal building blocks to create analog signal generators, analog power supplies, voltage splitters and more.

Data Acquisition Advances Focus on Interfacing
Jeff Child discusses the latest data acquisition solutions, with a look at how interface technologies have evolved.

Future of IoT Communications: Will Upgraded Cellular Networks Benefit IoT?
This guest essay by Andrew Girson, CEO of Barr Group, explores how IoT will fare in the 5G network era.


Block Diagram Reduction and Automatic Tuning
George Novacek steps through how to think in terms of block diagrams to help you reduce system complexity early on in a design.

Numeric Precision vs. DDS Calculations
Using the full frequency resolution of a DDS chip outstrips the capabilities of floating point numbers. Ed Nisley looks at high-res frequency calibration and measurements in the DDS realm.

Deadbolt the Uninvited: Locked Out of My Home
In this Part 2 of Jeff Bachiochi’s electronic lock story, he gets into some of the power and remote-control issues of his electronic deadbolt lock project.

Diagnosing Performance Variations in HPC
Ayse K. Coskun delves into how application performance variations can cause inefficiency
in high-performance computing (HPC) systems and how to diagnose these variations.

Microchip Launched Two New MCU Families

Microchip Technology has made available its new SAM D5x and SAM E5x microcontroller (MCU) families. These new 32-bit MCU families offer extensive connectivity interfaces, high performance and robust hardware-based security for a wide variety of applications. The SAM D5/E5 MCUs combine the performance of an ARM Cortex-M4 processor with a Floating Point Unit (FPU). This combination offloads the Central Processing Unit (CPU), increasing system efficiency and enabling process-intensive applications on a low-power platform.


Running at up to 120 MHz, the D5x and E5x MCUs feature up to 1 MB of dual-panel Flash with Error Correction Code (ECC), easily enabling live updates with no interruption to the running system. Additionally, these families are available with up to 256 KB of SRAM with ECC, vital to mission-critical applications such as medical devices or server systems.

These new MCUs have multiple interfaces that provide design flexibility for even the most demanding connectivity needs. Both families include a Quad Serial Peripheral Interface (QSPI) with an Execute in Place (XIP) feature. This allows the system to use high-performance serial Flash memories, which are both small and inexpensive compared to traditional pin parallel Flash, for external memory needs.

The SAM D5/E5 devices also feature a Secure Digital Host Controller (SDHC) for data logging, a Peripheral Touch Controller (PTC) for capacitive touch capabilities and best-in-class active power performance (65 microA/MHz) for applications requiring power efficiency. Additionally, the SAM E5 family includes two CAN-FD ports and a 10/100 Mbps Ethernet Media Access Controller (MAC) with IEEE 1588 support, making it well-suited for industrial automation, connected home and other Internet of Things (IoT) applications.

Both the SAM D5x and E5x families contain comprehensive cryptographic hardware and software support, enabling developers to incorporate security measures at a design’s inception. Hardware-based security features include a Public Key Cryptographic Controller (PUKCC) supporting Elliptic Curve Cryptography (ECC) and RSA schemes as well as an Advanced Encryption Standard (AES) cipher and Secure Hash Algorithms (SHA).

The SAM E54 Xplained Pro Evaluation Kit is available to kick-start development. The kit incorporates an on-board debugger, as well as additional peripherals, to further ease the design process. All SAM D5x/E5x MCUs are supported by the Atmel Studio 7 Integrated Development Environment (IDE) as well as Atmel START, a free online tool to configure peripherals and software that accelerates development. SAM D5x and SAM E5x devices are available today in a variety of pin counts and package options in volume production quantities. Devices in the SAM D5/E5 series are available starting at $2.43 each in 10,000 unit quantities. The SAM E54 Xplained Pro Evaluation Kit is available for $84.99 each.

Microchip | www.microchip.com

Don’t Miss Our Newsletter: IoT Technology Focus

In tommorrow’s IoT Technology Focus newsletter you’ll get news and trends about the products and technologies needed to build IoT implementations and devices.LoRa-NNNCo-PR-graphic-press

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” themed newsletter issue tomorrow.

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

Remember, our new enhanced weekly CC Newsletter will switch its theme each week, so look for these in upcoming weeks:

Embedded Boards. This content looks at embedded board-level computers. The focus here is on modules—Arduino, Raspberry Pi, COM Express, and other small-form-factor —that ease prototyping efforts and let you smoothly scale up production volumes.

Analog & Power. 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. 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.


August has a 5th Tuesday. So look for a bonus Newsletter this  month!

Cypress MCUs Selected for Toyota Camry Instrument Cluster

Cypress Semiconductor has announced that global automotive supplier DENSO has selected Cypress’ Traveo automotive microcontroller (MCU) family and FL-S Serial NOR Flash memory family to drive the advanced graphics in its instrument cluster for the 2017 Toyota Camry. The DENSO instrument cluster uses Traveo devices that Cypress says were the industry’s first 3D-capable ARM Cortex-R5 cluster MCUs.

Denso Instrument Cluster

The FL-S memory in the cluster is based on Cypress’ proprietary MirrorBit NOR Flash process technology, which enables high density serial NOR Flash memory by storing two bits per cell. The DENSO instrument cluster has 4.2- and 7.0-inch screens capable of audio, video and navigation in the center display of the 2017 Toyota Camry.

Cypress works with the world’s top automotive companies to support automotive systems including Advanced Driver Assistance Systems (ADAS), 3-D graphics displays, wireless connectivity, full-featured touchscreens and superior body electronics. Cypress’ automotive portfolio includes the Traveo MCU family, power-management ICs (PMICs), PSoC programmable system-on-chip solutions, CapSense capacitive-sensing solutions, TrueTouch touchscreens, NOR flash, F-RAM and SRAM memories, and USB, Wi-Fi and Bluetooth connectivity solutions. The portfolio is backed by Cypress’ commitment to zero defects, excellent service and adherence to the most stringent industry standards, such as the ISO/TS 16949 quality management system, the Automotive Electronics Council (AEC) guidelines for ICs and the Production Part Approval Process (PPAP).

Cypress Semiconductor | www.cypress.com

Digital Guitar Amplifier/Effects Processor

Part 2: Design and Construction

In the first part of this series, Brian introduced the Teensy 3.2 MCU module. Now he presents a digital guitar amplifier/effects unit that he built around two Teensy modules.

By Brian Millier

In the first part of this series, I introduced the PJRC Teensy family of Kinetis ARM-based modules. I emphasized how they are particularly well suited to audio applications due to the availability of a good audio library. In addition, they are supported by the Teensyduino add-in to the Arduino IDE. This month, I’ll describe the digital guitar amplifier/effects unit that I built around two Teensy modules.

The guitar amplifier/effects unit design is about 60% software and 40% hardware. The analog part of the audio signal chain is made up of a simple, one-transistor input buffer and a 20-W output amplifier (using an automotive audio power amplifier IC). A Teensy 3.2 MCU module and a Teensy Audio Adapter module handle all the audio signal processing…..

Read this article in the August 325 issue of Circuit Cellar

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Smart Power Switches Meet Automotive Needs

Infineon Technologies offers power IC manufacturing technology: SMART7. Infineon designed it specifically for automotive applications such as Body Control Modules or Power Distribution Centers. SMART7 power ICs drive, diagnose and protect loads in applications like heating, power distribution, air-conditioning, exterior and interior lighting, seat and mirror adjustment. They also provide a cost-effective and robust replacement of electromechanical relays and fuses. SMART7 is based on thin-wafer technology that reduces power losses and chip sizes. Based on SMART7, Infineon has introduced the two high-side power switch families PROFET+2 and High Current PROFET. The SPOC+2 multichannel SPI high-side power controllers will follow within a year.

Infineon High Res PROFET TSDSO-14

The PROFET+2 family was developed for automotive 12 V lighting load applications and capacitive loads. These comprise e. g. halogen bulbs in external lighting control, interior lighting and dimming, as well as LED lighting. PROFET+2 devices provide state-of-the-art diagnostics and protection features. They maintain pin-out compatibility with their predecessor family PROFET+ for zero-cost migration. There is no ECU layout change needed, if single-channel devices are replaced by dual-channel variants and vice versa. Compared to their predecessor family, the PROFET+2 devices are up to 40 percent smaller in package size and improve energy efficiency with 50 percent lower current consumption. Their mass production is planned to start as of Q4 2017 and later. All high-side switches will be qualified in accordance with AEC Q100.

Infineon Technologies | www.infineon.com

High Isolation DC/DC Converters Target Industrial Power

Murata has introduced a series of high isolation DC/DC converters developed by Murata Power Solutions. The MGJ6 wide, low-profile series converters feature a 14 mm creepage and clearance distance for use in reinforced-rated isolated-gate drive-power applications in higher efficiency 690 VAC industrial electrical distribution systems. They provide optimized voltages for best system performance and efficiency.

Murata mgj6_lp_14mm_pr

This high isolation DC-DC converter series is designed for powering high- and low-side gate-drive circuits for IGBTs and silicon and silicon carbide MOSFETs in bridge circuits used in motor control applications and industrial power installations. Rated at 6 W, the dual output converters provide a wide 2:1 input voltage range with nominal values of 5, 12 and 24 V, and with output voltages of 15/-10 V, 20/-5 V and 15/-5 V.

Suitable for power applications that require a DC link voltage up to 3 kVDC, asymmetric outputs provide an optimum drive level to maintain a high system efficiency with low EMI levels. With their frequency synchronization-capability and very low coupling capacitance, typically 13 pF, EMC compliance is easier

The converters’ compact design reduces board space and development time, whilst their characterized dV/dt immunity of 80 kV/microsecond gives users confidence in a long service life, and similarly the use of planar magnetics increases product reliability and repeatability of performance. Typical applications include motor drives/motion control, solar inverters, UPS, alternative energy (wind-power generators), high-power AC-DC conversion, traction, EV/HEV and welding.

The MGJ6 series converters offer an operating temperature range of -40 to 105 °C, with derating above 90 °C. Standard features of the patent protected converters include enable pin, short-circuit and overload protection, and a frequency synchronization pin that simplifies EMC filter design.

The series is pending IEC 61800-5-1 approval based on a high working voltage of 690 Vrms maximum between primary and secondary, and similarly is also pending UL approval to UL 60950 for reinforced insulation to a working voltage of 690 Vrms.

Murata Power Solutions | www.murata-ps.com

Kickstarter Enables Building LoRa IoT Gear in 3 Steps

Electronic Cats has launched a Kickstarter campaign called LoRaCatKitty to enable the building of Internet of Things (IoT) applications with LoRa in just three steps. LoRaCatKitty is designed to simplify the development of IoT applications using LoRa technology. It has based its development on the ESP8266 WiFi module and the LoRa RN2903 or RN2483 Microchip module.


The mobile application for LoRaCatKitty, allows you to generate and compile the firmware in the cloud and use your smartphone to transfer and the firmware to the board. All the necessary hardware libraries are accessible through the app so you can select, download and transfer them to your LoRa device directly. The solution uses Grove connectors that allow easy and quick use of sensors, actuators or external elements without the need for soldering. Users can just connect the blocks and build their project. LoRaCatKitty supports a long list of sensor modules with Grove connectors.

The LoRaCatKitty app for Android is used to wirelessly program the device and will allow beginners to develop an infinite number of applications in an easy and intuitive way. LoRaCatKitty is completely compatible with LoRaWAN platforms like The Things Network, Beelan and others, allowing you to access RESTful API resources which can be used to develop IoT apps easily with the sensors and actuators visualized.

Technical specs of the hardware:

  •     Class A LoRaWAN Soon support of Class C LoRaWAN
  •     Wi-Fi: 802.11b/g/n Encryption
  •     Wi-Fi: WEP/TKIP/AES
  •     Module ESP8266-12E Certified FCC
  •     Module RN2903 Certified FCC
  •     Power supply:battery port: 3.4 V to 4.2 V
  •     Micro USB: 5 V
  •     Output current: 1000 mA MAX
  •     Operating voltaje : 3.3 V
  •     Charging current: 500 mA MAX
  •     Flash memory: 4 MB
  •     Size: 50 mm x 50 mm
  •     Weight: 26 g

Don’t Miss Our Newsletter: Microcontroller Watch

In tommorrow’s Microcontroller Watch we’ll feature key updates on the latest microcontroller technology  — the latest MCU design wins — new MCU product announcements — MCU industry events –and more.35352057604_77bb4aab93_m

Plus: 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 “Microcontroller Watch” themed newsletter issue tomorrow.

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

Remember, our new enhanced weekly CC Newsletter will switch its theme each week, so look for these in upcoming weeks:

IoT Technology Focus. The Internet-of-Things (IoT) phenomenon is rich with opportunity. This newsletter tackles news and trends about the products and technologies needed to build IoT implementations and devices.

Embedded Boards. This content looks at embedded board-level computers. The focus here is on modules—Arduino, Raspberry Pi, COM Express, and other small-form-factor —that ease prototyping efforts and let you smoothly scale up production volumes.

Analog & Power. 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.


August has a 5th Tuesday. So look for a bonus Newsletter this  month!

Find and Eliminate Ground Loops

Everything had been fine with my home entertainment center—comprising a TV, surround-sound amplifier, an AM/FM tuner, a ROKU, and a CD/DVD/BlueRay player—until I connected my desktop PC, which stores many of my music and video files on one of its hard drives. With the PC connected, the speakers put out a low level, annoying, 60-Hz hum—a clear indication of a ground loop. All my audio and video (AV) devices are fairly new, quality, brand-name products equipped with two-prong power cords, so even though the PC has a three-prong plug, there should not be multiple signal returns causing the ground loop. This article describes an approach to eliminating ground loops in analog AV systems.


By definition, ground loops bring about unwanted currents flowing through two or more signal return paths. Thus induction coils are formed, usually of one turn only. These loops pick up interference signals from the environment. Because every conductor has a finite impedance, a voltage potential—Vi = Ig(R1 + R2)—develops between the two connected signal return points. This voltage is the source of the interference: a hum, hiss noise that high-frequency signals pick up (e.g., a local AM station), and so forth. A simplified example is illustrated in Figure 1.

FIGURE 1: Cause of the ground loop interference.

FIGURE 1: Cause of the ground loop interference.

An audio signal source VS in Figure 1—an audio card inside the PC, for example—is connected to an amplifier via a shielded cable. The shield is grounded at both ends to the chassis of both devices. Three-prong power plugs connect the chassis of both AV components to the house power distribution ground wire. Let’s consider the amplifier ground to be the reference point. (It doesn’t matter which point in the loop we pick.) The loop, comprising the cable shield and the power distribution ground wire, picks up all kinds of signals causing loop current Ig to flow and as a result interference voltage Vi to be generated.

Vi is added to the signal from the audio card. The Ig current induced into the loop comes from many potential sources. It can be induced in the ground wire by the current flowing in the 120-VAC hot and its return neutral wires, acting like a transformer. There can be leakages, induction by magnetic fields, capacitive coupling, or an electromagnetic interference (EMI) induction into the loop. Once Vi is added to the signal it is generally impossible to filter it out.

Much of electrical equipment requires the third power prong for safety. This is connected to the chassis and at the electrical distribution panel to the neutral (white wire) and the local ground—usually a metal stake buried in the earth. The earth ground is there to dissipate lightning strikes but has no effect on the ground loops we are discussing.
The ground wire’s primary purpose is safety plus transient and lightning diversion to ground. Under normal circumstances no current should flow through this wire. Should an internal fault in an appliance connect either the neutral (white) or the hot (black or red) wire to the chassis, the green wire shunts the chassis to the ground. Ground fault interrupters (GFI) compare the current through the hot wire to the return through the neutral. If not identical, the GFI disconnects.

Manufacturers of audio equipment know that grounding sensitive equipment at different places along the ground wire results in multiple returns causing ground loops. These facilitate the interference noise to enter the system. From the perspective of electrical safety, the small currents induced in the ground loop can be ignored. Unfortunately, they are large enough to play havoc with sensitive electronics. The simplest solution to the dilemma is to avoid creating ground loops by not grounding the AV equipment. Thus the two-prong plugs have been used on such equipment. To satisfy the safety requirements, the equipment is designed with double insulation, meaning that even in case of an internal fault, a person cannot come to contact with a live metallic part by touching anywhere on the surface of the equipment.

My PC, like most desktops, has a three-prong plug. Figure 2 shows the arrangement. The PC is grounded through its power cord. Unfortunately, the cable TV (CATV) introduces a second ground connection through its coax connector. I measured the resistance between the coax shield as it entered the house and the house power distribution ground wire. The resistance was 340 mΩ, indicating a hard connection between the coax shield and the house ground, the cause of the ground loop. I was unable to establish where that connection was made, but it wasn’t through the earth.

FIGURE 2: Ground loop in my entertainment system

FIGURE 2: Ground loop in my entertainment system

There can be multiple ground loops around a computer system if you have hard-wired peripherals with three-prong plugs, such as some printers, scanners and so forth. Digital circuits are much less sensitive to ground loops than the analog ones, but it is a good idea to minimize potential loops by connecting all your peripherals, other than wireless, into a single power bar.

Ground loops may also be created when long shielded cables are used to interface the PC and the home theatre box. Two shielded cables needed for stereo represent two signal returns creating a ground loop of their own. And then there are video cables. Another loop. Fortunately, connectors on the back of the PC and AV equipment are very close to each other, which means a minimal potential difference between them at low frequencies. Stereo cables keep the loop small. To minimize all the loops’ areas for interference pick-up, I have bundled the interface cables very close to each other with plastic wire ties. In severe situations re-routing the cables or the use of a metal conduit or wireless interfaces may be needed to kill the interference.


Having disconnected the CATV cable from the TV, the hum went away. As well, temporarily replacing the PC with a laptop, which is not grounded, also fixed the problem. So how else can we fix those offending multiple returns?

The obvious answer is to break the loop. I strongly suggest you don’t disconnect the PC from the ground by using a two-prong plug adapter or just cutting the ground prong off. It will render your system unsafe. What you need is a ground isolator. Jensen Transformers, for example, sell isolators such as VRD-IFF or PC-2XR to break the ground connection, but you can build one for a small fraction of the purchase price. Figure 3 and Figure 4 show you how.

FIGURE 3: Ground isolator for CATV coax

FIGURE 3: Ground isolator for CATV coax

To break the ground loop caused by the CATV, you can make a little gizmo shown in Figure 3. J1 and J2 are widely available cable TV female connectors. C1 and C2 capacitors placed between them should be about 0.01 µF each. The assembly does not require a printed circuit board. You might place it in a tiny box or just solder everything together, wrap it with electrical tape, and put it somewhere out of the way. Remember that the capacitors’ working voltage must be at least double the power distribution voltage. That is 250 V in North America and more than 500 V elsewhere in the world.

FIGURE 4: Ground isolator for three-prong powered appliances

FIGURE 4: Ground isolator for three-prong powered appliances

Figure 4 shows how to break ground for appliances, such as a PC, with three-prong plugs. You can build this circuit into a computer or another appliance, but I find it better to build it as an independent break-out box. The diodes provide open loop for signals up to about 1.3 VPP. A hum is usually of a substantially lower amplitude. C1, 0.01 µF, provides bypass for high-frequency EMI to ground. The loop would be closed for voltages higher than 1.3 VPP, such as the ones due to isolation fault of the hot wire to the chassis. For 120 VAC distribution, D1, D2, and C1 should be rated for 250 V at a minimum. In a circuit branch with a 15-A breaker or fuse, the diodes need to be rated for a minimum of 20 A so that the breaker opens up before the diodes blow. If the appliance takes only a fraction of the rated fuse current, say 2 A, you could use 5-A diodes and include an optional fuse rated for 2 A. For countries with 230-VAC power, the components must be rated accordingly.

You can also break the ground loop by using a power isolation transformer between the power line and the PC, or quality signal transformers on the signal lines. The downside of this is that good isolation and signal transformers are costly and not widely available. Equipment powered from wall warts—and especially those with optically coupled inputs and outputs, common today—is inherently ground loop impervious.


This article describes an approach to eliminating ground loops in analog AV systems. While you need to understand how ground loops occur, finding them and eliminating their effects may turn out to be a matter of frustrating trial and error.

George Novacek is a professional engineer with a degree in Cybernetics and Closed-Loop Control. Now retired, he was most recently president of a multinational manufacturer for embedded control systems for aerospace applications. George wrote 26 feature articles for Circuit Cellar between 1999 and 2004. Contact him at gnovacek@nexicom.net with “Circuit Cellar” in the subject line.

This article appears in Circuit Cellar 301 August 2015.

Robots with a Vision

Machine chine vision is a field of electrical engineering that’s changing how we interact with our environment, as well as the ways by which machines communicate with each other. Circuit Cellar has been publishing articles on the subject since the mid-1990s. The technology has come a long way since then. But it’s important (and exciting) to regularly review past projects to learn from the engineers who paved the way for today’s ground-breaking innovations.

In Circuit Cellar 92, a team of engineers (Bill Bailey, Jon Reese, Randy Sargent, Carl Witty, and Anne Wright) from Newton Labs, a pioneer in robot engineering, introduced readers to the M1 color-sensitive robot. The robot’s main functions were to locate and carry tennis balls. But as you can imagine, the underlying technology was also used to do much more.

The engineering team writes:

Machine vision has been a challenge for AI researchers for decades. Many tasks that are simple for humans can only be accomplished by computers in carefully controlled laboratory environments, if at all. Still, robotics is benefiting today from some simple vision strategies that are achievable with commercially available systems.

In this article, we fill you in on some of the technical details of the Cognachrome vision system and show its application to a challenging and exciting task—the 1996 International AAAI Mobile Robot Competition in Portland, Oregon… In 1996, the contest was for an autonomous robot to collect 10 tennis balls and 2 quickly and randomly moving, self-powered squiggle balls and deliver them to a holding pen within 15 min.

In M1’s IR sensor array, each LED is fired in turn and detected reflections are latched by the 74HC259 into an eight-bit byte.

In M1’s IR sensor array, each LED is fired in turn and detected reflections are latched by the 74HC259 into an eight-bit byte.

At the time of the conference, we had already been manufacturing the Cognachrome for a while and saw this contest as an excellent way to put our ideas (and our board) to the test. We outfitted a general-purpose robot called M1 with a Cognachrome and a gripper and wrote software for it to catch and carry tennis balls… M1 follows the wall using an infrared obstacle detector. The code drives two banks of four infrared LEDs one at a time, each modulated at 40 kHz.

The left half of M1’s infrared sensor array is composed of a Sharp GP1U52X infrared detector sandwiched between four infrared LEDs

The left half of M1’s infrared sensor array is composed of a Sharp GP1U52X infrared detector sandwiched between four infrared LEDs

Two standard Sharp GP1U52X infrared remote-control reception modules detect reflections. The 74HC163/74HC238 combination fires each LED in turn, and the ’HC259 latches detected reflections. This system provides reliable obstacle detection in the 8–12″ range.

The figure above shows the schematic. The photo shows the IR sensors.

The system provides only yes/no information about obstacles in the eight directions around the front half of the robot. However, M1 can crudely estimate distance to large obstacles (e.g., walls) via patterns in the reflections. The more adjacent directions with detected reflections, the closer the obstacle probably is.

Download the Entire Article

PC/104 Card Features DMP Vortex DX-3 SoC

WIN Enterprises has announced the MB-83310, a PC/104 module featuring the economical DMP Vortex86 DX3-9126 processor which is mounted onboard. Power consumption of the dual-core SoC is only approximately 6W. The unit supports multiple VGA-LVDS displays with a maximum resolution of 1920×1440 at 60Hz. Operating systems support includes Microsoft Windows and Linux. The device is ideal for IIoT domain gateways, home IoT gateways, thin clients, and NAT Routers.

WIN Enterprises MB-83310 Editors

The board meets the PC/104 Specification 2.6 and supports the PC/104+ and PC/104 connector onboard. On board memory includes 2 Gbytes of DDR3L 1333. Its dual LAN connector with 2×10 pin header (1 x GbE,1 x Fast Ethernet). I/O consists of 4x USB 2.0, 2x COM Port (COM2 Port is RS-232/422/485, COM1 (RS232 only). For mass storage, there is 1x SATA Port (1×7 Pin),1xM.2 Socket (2242 only). The board’s DC 5V Power input is AT/ATX mode select by jumper. Operating temperature ranges from -20° C to 70° C.

WIN Enterprises | www.win-ent.com

Single-Chip Battery Controllers Enable USB Power Delivery

Texas Instruments (TI) has introduced a pair of highly flexible, single-chip buck-boost battery charge controllers for one- to four-cell (1S to 4S) designs. The bq25703A and bq25700A synchronous charge controllers support efficient charging through USB Type-C and other USB ports in end equipment ranging from notebooks and tablets to power banks, drones and smart home applications. To learn more about the bq25703A and bq25700A.

TI bq25703A-bq25700A

Supporting both I2C and SMBus interfaces, the bq25703Aand bq25700A feature a new advanced battery algorithm enabling full power output by adding intelligence to battery charging through maximum power point tracking technology. The unique algorithm, referred to as input current optimization (ICO), automatically detects the full capacity of input power to optimize current, while maintaining consistent system and charging current to ensure the utilization of maximum input power.

Key features and benefits

  • Input source flexibility: The device’s USB Power Delivery compatibility offers an input voltage range from 3.5 V to 24 V, which designers can use in multiple ports including USB 2.0, USB 3.0 and the newest standard, USB Type-C.
  • Wide USB On-the-Go (OTG) output compatibility: The new charge controllers support input-ready devices from 5 V to 20 V and adjustable output for USB OTG with programmable current regulation.
  • Compact configurations: TI’s new battery-charging algorithm and intelligent detection features enable the battery charge controllers to support wide input and output voltage ranges and more compact adaptor designs.
  • Seamless transition between different modes : The devices support 1S to 4S batteries and an efficient transition between buck and boost operation without any dead zone.

Designers can use the bq25700A evaluation module (EVM) to easily evaluate device features and performance and speed time to market. The bq25703A EVM and the bq25700A EVM  are available from the TI store and authorized distributors for US$149.00. Designers can use the WEBENCH Battery Charger Designer to calculate the efficiency of the battery charge controller.

The bq25703A and bq25700A charge controllers are now available through the TI store and authorized distributors. Offered in a 4-mm-by-4-mm, 32-pin quad flat no-lead (QFN) package, the controllers are priced at US$2.20 in 1,000-unit quantities.

Texas Instruments | www.ti.com

Reliability and Failure Prediction: A New Take

HALT methodology has been a popular way to test harsh environment reliability. A new approach involves PCB design simulation for vibration and acceleration for deeper yet faster analyses.

By Craig Armenti & Dave Wiens—Mentor Board Systems Division

Many electronic products today are required to operate under significant environmental stress for countless hours. The need to design a reliable product is not a new concept, however, the days of depending on a product’s “made in” label as an indicator of reliability are long gone. PCB designers now realize the importance of capturing the physical constraints and fatigue issues for a design prior to manufacturing to reduce board failure and improve product quality.

Simulation results should be available in a two-phase post-processor for each simulation, providing broad input on the PCB’s behavior under the defined conditions.

Simulation results should be available in a two-phase post-processor for each simulation, providing broad input on the PCB’s behavior under the defined conditions.

Although every product is expected to fail at some point. That’s inevitable. But premature failures can be mitigated through proper design when proper attention is paid to potential issues due to vibration and acceleration. ….

Read this article in the August 325 issue of Circuit Cellar

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Zero-Drift Op Amp Consumes Only 1.3 μAmps

Analog Devices,  which recently acquired Linear Technology, has announced the LTC2063 zero-drift op amp which draws just 1.3μA typ (2μA max) on a 1.8V supply. This micropower amplifier maintains high precision: maximum input offset voltage is 5μV at 25°C, maximum drift is 0.06μV/°C from –40°C to 125°C. Maximum input bias current is 15pA at 25°C, and 100pA from –40°C to 125°C. These high precision input characteristics allow the use of large value feedback network resistors, keeping power consumption low without compromising accuracy, even at elevated temperature.


Rail-to-rail inputs and outputs simplify single supply use and enhance dynamic range. An integrated EMI filter provides 114dB electromagnetic interference rejection at 1.8GHz. With low 1/f noise inherent to its zero-drift architecture the LTC2063 is well suited for amplifying and conditioning low frequency sensor signals in high temperature industrial and automotive systems as well as portable and wireless sensor network applications.

The LTC2063 is available in SOT-23 and SC70 packages. The SC70 version includes a shutdown mode which reduces current consumption to just 90nA when the amplifier is not in use. This enables ultralow power duty cycled sensor applications. For example, a precision low duty cycle oxygen sensor circuit shown in the data sheet consumes less than 200nA average current.

The LTC2063 works well with Dust Networks’ SmartMesh wireless sensor networks, expanding the reach of precision measurements to places previously not practical. An example is the DC2369A wireless current sense reference board which uses the LTC2063 and LTP5901-IPM SmartMesh IP module and other micropower components to create an isolated floating current sense measurement platform which operates for years on small batteries.

The LTC2063 operates on supply voltages from 1.7V to 5.25V and is fully specified from –40°C to 125°C. Pricing starts at $1.50 each in 1,000-piece quantities.

Linear Technology | www.linear.com