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

SWIFT DC/DC Buck Converters Reduce EMI

Texas Instruments recently launched the industry’s first 20-A and 30-A synchronous DC/DC buck converters with frequency synchronization for low-noise and reduced EMI/EMC and a PMBus interface for adaptive voltage scaling (AVS). The SWIFT 20-A TPS544B25 and 30-A TPS544C25 converters integrate MOSFETs and feature small PowerStack QFN packages to drive ASICs in space-constrained and power-dense applications. When used with TI’s WEBENCH online design tools, the converters simplify power conversion and speed the power supply design process. TI Swift

The highly integrated converters feature 0.5% reference-voltage accuracy, as well as full differential remote-voltage sensing. Frequency synchronization to an external clock eliminates beat noise and reduces EMI. Moreover, the TPS544B25 and TPS544C25 offer pin-strapping that enables the devices to start up without PMBus commands to an output voltage set by a single resistor. Programmability, real-time monitoring of the output voltage, current and external temperature, and fault reporting via PMBus simplify power-supply design, increase reliability, and reduce component count and system cost.

Together, the TPS544C25 and UCD90240 provide a complete PMBus point-of-load (POL) and sequencing solution. Download the Complete PMBus Power System for Enterprise Ethernet Switches TI Designs reference design.

TPS544B25 and TPS544C25 key features and benefits:

  • Integrated power MOSFETs support 20-A and 30-A of continuous output current.
  • On-chip PMBus interface and non-volatile memory simplify power-supply design and enable customization. Read a blog post on “PMBus – what is the value anyway?”
  • Voltage-control mode with input feed-forward improves noise margin and responds instantly to input voltage changes.
  • Other features include internal soft start, input under-voltage protection, thermal shutdown and a reset function.

The TPS544B25 costs $4.08 in 1,000-unit quantities. The TPS544C25 is $4.49 in 1,000-unit quantities. Evaluation modules are available.

Source: Texas Instruments

NXP’s New Automotive Ethernet Product Portfolio

NXP Semiconductors has launched product portfolio for automotive Ethernet that builds on BroadR-ReachT, which is an automotive standard defined by theOPEN Alliance industry group. NXP’s automotive portfolio features two product families: Ethernet transceivers (TJA1100) and Ethernet switches (SJA1105).

The Ethernet PHY TJA1100 supports automotive low power modes. The systems sleep when the engine is off. However, the Ethernet PHY stays partially powered and wakes up the system only when there is network activity.NXP_AutomotiveEthernet

Transceivers (TJA1100):

  • Compliant with the OPEN Alliance BroadR-Reach (OABR) standard (IEEE: 100BASE-T1)
  • Designed via an automotive development flow
  • 6 × 6 mm² HVQFN package with minimal external component count
  • Supports low-power modes to save battery life
  • Automotive grade ESD and EMC

NXP’s SJA1105 Automotive Ethernet Switch uses Deterministic Ethernet technology to guarantee message latency in applications such as autonomous driving, where deterministic communication is vital for reasons of operational efficiency or functional safety. Deterministic Ethernet supports the trend toward increasing bandwidth requirements of up to one gigabit, while ensuring high reliability in networked control systems and high availability in fail-operational applications. It comprises several standards, including Ethernet (IEEE 802.3), Time-Triggered Ethernet (SAE AS6802) as well as Audio Video Bridging (AVB), and Time-Sensitive Networking (TSN).

Digital Switch (SJA1105):

  • Five-port automotive Ethernet Switch supporting up to 1-Gb network speed
  • Layer 2 Store and Forward Switch
  • MII/RMII/RGMII Interface
  • Port Mirroring and VLAN support (IEEE 802.1Q and IEEE 802.1P)
  • AVB and TSN support
  • Enables Deterministic Ethernet solutions

TJA1100 Ethernet transceivers are available in prototype samples. They will enter mass production in late 2015. SJA1105  Ethernet Switches are available upon request.

Source: NXP Semiconductors

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.

TRACE32 Supports Spansion HyperFlash Memory

Lauterbach recently announced its support for the Spansion HyperFlash Memory with the TRACE32 tools. HyperBus Interface was introduced by Spansion in 2014 as an improvement on today’s low pin count memory interfaces and has been broadly implemented by the system-on-chip (SoC) manufactures.trace32_Lauterbach

HyperFlash Memory is based on the HyperBus interface and provides the important characteristics such as low latency, high read throughput, and space efficiency. TRACE32 tools support the HyperFlash memory with the intuitive, fast, and flexible Flash Programming feature that also provides you with control of reading, displaying, and erasing the content of the flash memory. The content is displayed in a standard hex dump, which allows the contents to be checked quickly. The tool supports the pairing of HyperFlash memory with the HyperBus interface and also with the ordinary Quad SPI controller.

Source: Lauterbach

Universal Trigger and Decoder Option for R&S Digital Oscilloscopes

Rohde & Schwarz has expanded its range of trigger and decoder options for the R&S RTO and R&S RTE digital oscilloscopes. With the R&S RTx-K50, the oscilloscopes help you debug serial protocols that employ Manchester or NRZ coding. The option can be used with a variety of standardized buses (e.g., PROFIBUS, DALI, or MVB) as well as with proprietary serial protocols. Developers of products that use these types of interfaces can easily find implementation errors and so test and release their designs more quickly.RTO-Rohde

The option, which covers data rates of up to 5 Gbps, supports up to 50 different telegram formats, while the format of the serial bus can be configured flexibly. You can define your own preamble, frame ID, data, CRC and other telegram fields. Protocol decoding also takes Manchester code violations into account.

High acquisition rates and minimal blind times are provided by the hardware-based trigger implementation on the oscilloscopes. You can trigger on telegram and data content with the R&S RTx-K50 option. The decoded protocol content is displayed in an easy-to-read, color-coded format. Time correlation with the analog signal makes it easy to identify faults caused by signal integrity problems. A tabular list of the protocol contents is also provided. The standard mask test with up to 600,000 tests per second makes it possible to check the signal quality faster with an eye diagram than with any other solution. In addition, both oscilloscope series from Rohde & Schwarz support the option of decoding up to four different serial protocols in parallel.

Source: Rohde & Schwarz

RED EXPERT Online Design Tool for Precise AC Loss Calculation

Würth Elektronik recently published RED EXPERT,  a new online tool you can use to simulate the power inductors. With just a few clicks, you can select the power inductors and calculate the complete AC losses.Wurth-RedExpert

RED EXPERT enables extremely precise loss calculation because it is not based on the known Steinmetz models with sinusoidal excitation. Instead, it is derived and validated from measurements of the power inductors in a switching controller setup.

The losses determined with RED EXPERT are based on current and voltage waveforms typical in applications. Besides the core and winding losses, they also include the losses arising from the specific geometries of the inductance, such as the air gap.

Particular highlights of the RED EXPERT AC loss model are the range of duty cycles supported from 10% to 90% and the switching frequency range of 50 kHz to 5 MHz. This gives the RED EXPERT AC loss model a previously unattained precision.

RED EXPERT is freely available in German, English, Spanish, Japanese, Russian, and Chinese at www.we-online.com/redexpert.

Source: Würth Elektronik

Two-Pin, Self-Powered Serial EEPROM for the IoT

Atmel recently announced a two-pin, single-wire EEPROM intended for the Internet of Things (IoT), wearables, and more. The self-powered devices don’t require a power source or VCC pin, with a parasitic power scheme over the data pin. They provide ultra-low power standby of 700 nA, 200 µA for write current, and 80 µA for read current at 25°C.

The AT21CS01/11 devices eliminate the need for external capacitors and rectifiers with its parasitic power scheme over a single data pin. Plus, their ultra-high write endurance capability to allow more than 1 million cycles for each memory location to meet the requirements for today’s high-write endurance applications.

The AT21CS01/11 products include a simple product identification with a plug-and-play, 64-bit unique serial number in every device. Furthermore, they deliver industry-leading electrostatic discharge (ESD) rating (IEC 61000-4-2 Level 4 ESD Compliant), so a variety of applications (e.g., cables and consumables) can tolerate exposure to the outside environment or direct human contact while still delivering high performance.

The new devices follow the I2C protocol, which enables easy migration from existing EEPROM with less overhead and the capability to connect up to eight devices on the same bus. The AT21CS01 devices offer a security register with a 64-bit factory programmed serial number and an extra 16 bytes of user-programmable and permanently lockable storag.

The AT21CS01 is intended for low-voltage applications operating at 1.7 to 3.6 V. For applications that require higher voltage ranges (e.g., Li-Ion/polymer batteries), the AT21CS11 supports a 2.7 to 4.5 V operating range.

The AT21CS01 devices are available in production quantities in three-lead SOT23, eight-lead SOIC, and four-ball WLCSP. Pricing starts at $0.32 in 5,000-piece quantities. The AT21CS11 will be available in Q4 2015.

Source: Atmel

Matrix Launches Formula AllCode Kickstarter Campaign (sponsored)

Matrix TSL has launched a Kickstarter campaign for its Formula AllCode robotics course, which features a high-specification, Bluetooth-enabled robot. You can program the robot via Python, AppBuilder, Flowcode, Matlab, LabVIEW, C, and more. It is compatible with Raspberry Pi, Android, iPhone, and Windows devices.AllCodeKickstarter


Formula AllCode is a platform for both novice or advanced electronics enthusiasts to learn and test their robotics skills. Participate in the campaign: Formula AllCode

The funds raised from this Kickstarter project will allow Matrix to take the current prototype development shown in the project videos to the next level with a technical specification to beat any other like-for-like robot buggy and subsequent manufacture of 1000 units to be launched world-wide.

By backing the  Kickstarter campaign, you are supporting a project which allows users to develop their robotics understanding on a platform of their choice. Whether your starting out with your first robotics project or you’re a fully fledged robotics developer, the Formula AllCode will work for you. The project must be funded by Sunday, September 6, 2015.AllCodeSpecs



  • 2 Push to make switch
  • 8 IR distance sensors
  • Light sensor
  • Microphone
  • I2C accelerometer/compass
  • 2 Line following sensors
  • Audio gain


  • 8 LEDs (one port)
  • Speaker
  • Expansion port (8 bit)
  • 4 Servo outputs
  • E-blocks expansion port


  • Left and Right
  • Integrated gear box
  • Integrated encoders


  • Reset switch
  • 16-bit PIC24 microcontroller
  • USB rechargeable lithium battery
  • 4 × 40 char backlit LCD
  • Micro SD card
  • Integrated Bluetooth
  • Crystal Oscillator
  • Micro USB Socket

Q&A: Innovations in Wearables and Virtual Reality

New developments in wearable technology, virtual reality, and augment reality research are poised to change everything from healthcare to gaming. We recently asked Professor Bruce Thomas to tell us about the research in these areas taking place at the Wearable Computer lab at the University of South Australia.

Professor Bruce Thomas is the Deputy Director of the Advanced Computing Research Centre and Director of the Wearable Computer Lab at the University of South Australia. Prof. His work is focused on wearable computers, tabletop interactions, augmented reality, and user interaction.

Professor Bruce Thomas is the Director of the Wearable Computer Lab at the University of South Australia.

CIRCUIT CELLAR: In 1997, Carnegie Mellon, Georgia Tech, and MIT hosted the first IEEE International Symposium on Wearable Computers. How has research in the area changed since the late 1990s?

BRUCE: I remember the 1997 conference well. We presented one of our first wearable computer papers there. Some differences are: People do not build their own wearable computers anymore. Back then you had to hack your own system. Today you buy a smartphone and you have all the computing power you need.  We now use Mac minis, and this replaces about five or six components when we started. The research now is very focused on contextual aware computing. In 1997 the focus was on all disciplines of computer science. There is less work on garment integrated systems today. A large advantage is there are many computing and wearable platforms to start with.

CIRCUIT CELLAR: How did the Wearable Computer Lab at the University of South Australia come into being in 1998?

BRUCE: Someone in the Australian Defense Science and Technology Organization (a defense lab) showed me two Phoenix 486 belt mounted wearable computers with Private Eye head-mounted displays (HMDs). He told me this was the next big thing for defense, and he asked how I can help him out with some research. He wanted to use the new Sony Glasstron see-through displays. The first thing I thought of was, “This would be great for outdoor augmented reality.”

The ARQuake system is an interactive outdoor augmented reality collaboration system that enables users to walk around in the real world while playing the computer game Quake. The system requires a head-mounted display. (Image used with permission from Bruce H. Thomas, Wearable Computer Lab, University of South Australia)

The ARQuake system is an interactive outdoor augmented reality collaboration system that enables users to walk around in the real world while playing the computer game Quake. The system requires a head-mounted display. (Image used with permission from Bruce H. Thomas, Wearable Computer Lab, University of South Australia)

CIRCUIT CELLAR: You supervised Wayne Piekarski’s Tinminth augmented reality backpack project, which started in the late 1990s. Can you give us a brief overview of the project and how it evolved from 1998 to 2006?

BRUCE: The project went from a fixed frame for a backpack used in bush walking loaded with many devices to a belt-mounted system with just the Mac mini modified and a helmet (with many sensors and HMD). I wanted to port this onto a smartphone, but we never got there. The project had many different software architectures. The system was a research platform to support outdoor augmented reality user interaction research. The system was very flexible and robust.

CIRCUIT CELLAR: Which of the Lab’s current projects most interests you at this time?

BRUCE: We are interested in portable haptic devices. Dr. Ross Smith is leading the research effort into this. This involves layered jamming placed in a mitten to provide mobile haptic sensations to the user. This was presented at the International Symposium on Wearable Computing in 2014. We are continuing this work.

Wearable Jamming Mitten for virtual environment haptics developed by Tim Simon with Dr. Ross Smith and Professor Bruce H. Thomas (Image used with permission from Bruce H. Thomas, Wearable Computer Lab, University of South Australia)

Wearable Jamming Mitten for virtual environment haptics developed by Tim Simon with Dr. Ross Smith and Professor Bruce H. Thomas (Image used with permission from Bruce H. Thomas, Wearable Computer Lab, University of South Australia)

CIRCUIT CELLAR: Can you tell us about your most current project or projects at the Lab?

BRUCE: We have moved into large-scale projector-based augmented reality.  We are looking into tools to support designers of large spaces, but command and control rooms. We are about to start a seven year project working with Jumbo Vision International with the Innovative Manufacturing CRC.

CIRCUIT CELLAR: In an April 2015 TechTimes.com article, “Augmented Reality vs. Virtual Reality,” Vamien McKalin writes: “It is clear that the way things are right now, AR has the upper hand against VR, and that might not be changing anytime soon.” Do you agree?

BRUCE: It all comes down to who wins the head-mounted display wars. I think both will be winners in the near future. They solve different problems and have different uses. I can see a VR HMD attached to many games controllers, and I can see people using AR displays in their workplace.

This is a virtual reality simulation system that supports research relating to chronic neck pain therapies developed by Dr. Markus Broecker and Dr. Ross Smith. (Image used with permission from Bruce H. Thomas, Wearable Computer Lab, University of South Australia)

This is a virtual reality simulation system that supports research relating to chronic neck pain therapies developed by Dr. Markus Broecker and Dr. Ross Smith. (Image used with permission from Bruce H. Thomas, Wearable Computer Lab, University of South Australia)

CIRCUIT CELLAR: When you think about the short term (5 to 10 years), in which area do you think wearable technology will make the biggest impact: consumer, healthcare, military, or enterprise?

BRUCE: In 5 to 10 years, I think the biggest impact will be in healthcare. Wearables will go beyond fitness monitoring to health monitoring. This will enable better monitor of health issues and provide doctors much more diagnostics to help people. A second area is extending the ability for elderly people to stay in their homes. Better health monitoring and activity monitoring will allow people to safely stay at home longer.

The complete interview appears in Circuit Cellar 301 (August 2015).

New 16- and 32-Mb Advanced Low-Power SRAMs

Renesas Electronics recently introduced two new Advanced Low Power SRAMs with more than 500 times the resistance to soft errors compared to full CMOS memory cells. Fabricated using the 110-nm process, the new RMLV1616A Series of 16-Mb devices and the RMWV3216A Series of 32-Mb devices feature an innovative memory cell technology that improves reliability and leads to longer battery life.

The Advanced LP SRAM devices feature their memory cell technology that delivers soft error resistance over 500 times that of conventional full CMOS memory cells. Thus, it’s an intelligent solution for use in measurement devices, smart grid-related devices, and industrial equipment.

Features and specs:

  • Advanced LP SRAM technology for improved soft error resistance and enhanced reliability
  • Reduction of standby current tfor longer backup battery service life. Low current consumption levels are less than half the levels of comparable earlier Renesas SRAM products
  • The 16-Mb RMLV1616A Series is available in three packages: 48-ball FBGA, 48-pin TSOP, and 52-pin µTSOP
  • The 32-Mb RMWV3216A Series is available in a 48-ball FBGA package.

Samples of the RMLV1616A Series and RMWV3216A Series will be available in September. The 16-Mb RMLV1616A Series costs $16.50 per unit. The 32-Mb RMWV3216A Series is priced at $31 per unit. Mass production is scheduled to begin in October 2015.

Source: Renesas Electronics Corp.

New User-Friendly Platform for Designing Embedded Solutions

Applied Micro Circuits Corp. recently announced the availability of the HeliX 2 Development Kit to support its HeliX 2 family of 64-bit multicore processors. A complete hardware and software solution, the new kit is user-friendly platform for designing embedded systems.

The kit’s features and specs include:

  • Mini-ITX board form factor
  • Quad-core HeliX 2 processor running up to 2.0 GHz
  • Two DDR3 DIMMS
  • One PCIe 3.0 (x4) and two PCIe 3.0 (x1)
  • One SFP+ Ethernet connector to support 10 GbE
  • Four 1 GbE ports
  • One SATA 3.0 port
  • Support for USB 3.0, I2C, SPI, SDIO and UARTs
  • SMP Linux and full suite of development tools
  • On-board JTAG connector interfaces to third party tools for run-time debugging

The HeliX 2 Development Kit is available via AppliedMicro’s channel partners.

Source: Applied Micro Circuits Corporation


Advantech Offers Full Support of Microsoft Windows 10 IoT

Advantech now supports Windows 10 IoT (Internet of Things), which is intended to power a wide variety of intelligent connected devices, such as mobile point-of-sale units, robots, and medical equipment. Windows 10 IoT is designed to connect through Azure IoT Services and to provide enterprise-grade security along with machine-to-machine and machine-to-cloud connectivity.AdvantechWin10

Advantech offers diverse platforms with Windows 10 IoT preinstalled, including boards, systems, and gateways. Advantech WISE-PaaS Platform as a Service supports Windows 10 IoT with Core, Mobile, and Industry versions through Universal Windows Apps structure to offer Cloud Services. With it, developers can rapidly build applications and easily and deploy IoT cloud solutions.

Source: Advantech Corp.

August Electrical Engineering Challenge Live (Sponsor: NetBurner)

Ready to put your electrical engineering skills to the test? The August Electrical Engineering Challenge (sponsored by NetBurner) is live.

This month, find the error in the schematic posted below (and on the Challenge webpage) for a chance to win a NetBurner MOD54415 LC Development Kit ($129 value) or a Circuit Cellar Digital Subscription (1 year).


Find the error in the code and submit your answer via the online Submission Form by the deadline: 2 PM EST on July 20, 2015. Two prize winners from the pool of respondents who submit the correct answer will be randomly selected.

Find the error in the schematic and submit your answer via the online Submission Form by the deadline: 2 PM EST on August 20, 2015. Two prize winners from the pool of respondents who submit the correct answer will be randomly selected.


Out of each month’s group of entrants who correctly find the error in the code or schematic, one person will be randomly selected to win a NetBurner IoT Cloud Kit and another person will receive a free 1-year digital subscription to Circuit Cellar.

  • NetBurner MOD54415 LC Development Kit: You can add Ethernet connectivity to an existing product or use it as your product’s core processor! The NetBurner Ethernet Core Module is a device containing everything needed for design engineers to add network control and to monitor a company’s communications assets. The module solves the problem of network-enabling devices with 10/100 Ethernet, including those requiring digital, analog, and serial control.NetburnerMod54415module
  • Circuit Cellar Digital Subscription (1 year): Each month, Circuit Cellar magazine reaches a diverse international readership of professional electrical engineers, EE/ECE academics, students, and electronics enthusiasts who work with embedded technologies on a regular basis.Circuit Cellar magazine covers a variety of essential topics, including embedded development, wireless communications, robotics, embedded programming, sensors & measurement, analog tech, and programmable logic.


Read the Rules, Terms & Conditions


NetBurner solves the problem of network enabling devices, including those requiring digital, analog and serial control. NetBurner provides complete hardware and software solutions that help you network enable your devices.netburneroffer

NetBurner, Inc.
5405 Morehouse Dr.
San Diego, CA 92121 USA

Trends in Custom Peripheral Cores for Digital Sensor Interfaces

Building ever-smarter technology, we perpetually require more sensors to collect increasing amounts of data for our decision-making machines. Power and bandwidth constraints require signals from individual sensors to be aggregated, fused and condensed locally by sensor hubs before being passed to a local application processor or transmitted to the cloud.

FPGAs are often used for sensor hubs because they handle multiple parallel data paths in real time extremely well and can be very low power. ADC parallel interfaces and simple serial shift register interfaces are straightforward to implement in FPGA logic. However, interfacing FPGAs with more complex serial devices—which are becoming more common as analog and digital circuitry are integrated—or serializing collected data is often less straightforward. Typically, serial interfaces are implemented in FPGA fabric as a state machine where a set of registers represents the state of the serial interface, and each clock cycle, logic executes depending on the inputs and state registers. For anything but the most trivial serial interface, the HDL code for these state machines quickly balloons into a forest of parallel if-elseif-else trees that are difficult to understand or maintain and take large amounts of FPGA fabric to implement. Iterating the behavior of these state machines requires recompiling the HDL and reprogramming the FPGA for each change which is frustratingly time consuming.

Custom soft cores offer an alternate solution. Soft cores, sometimes known as IP cores, are not new in FPGA development, and most FPGA design tools include a library of cores that can be imported for free or purchased. Often these soft cores take the form of microcontrollers such as the Cortex M1, Microblaze, lowRISC, etc., which execute a program from memory and enable applications to be implemented as a combination of HDL (Verilog, VHDL, etc.) and procedural microcode (assembly, C, C++, etc.).

While off-the-shelf soft core microprocessors are overkill and too resource intensive for implementing single serial interfaces, we can easily create our own custom soft cores when we need them that use fewer resources and are easier to program than a state machine. For the purpose of this article, a custom soft core is a microcontroller with an instruction set, registers, and peripheral interfaces created specifically to efficiently accomplish a given task. The soft core executes a program from memory on the FPGA, which makes program iteration rapid because the memory can be reprogrammed without resynthesizing or reconfiguring the whole FPGA fabric. We program the soft core procedurally in assembly, which mentally maps to serial interface protocols more easily than HDL. Sensor data is made available to the FPGA fabric through register interfaces, which we also define according to the needs of our application.

Having implemented custom soft cores many times in FPGA applications, I am presently developing an open-source example/template soft core that is posted on GitHub (https://github.com/DanielCasner/i2c_softcore). For this example, I am interfacing with a Linear Technology LTC2991 sensor that has internal configuration, status, and data registers, which must be set and read over I2C (which is notoriously difficult to implement in HDL). The soft core has 16-bit instructions defined specifically for this application and executes from block ram. The serial program is written in assembly and compiled by a Python script. I hope that this example will demonstrate how straightforward and beneficial creating custom soft cores can be.

While I have been discussing soft cores for FPGAs in this article, an interesting related trend in microprocessors is the inclusion of minion cores, sometimes also called programmable real-time units (PRUs) or programmable peripherals. While not fully customizable as in FPGA fabric, these cores are very similar to the soft cores discussed, as they have limited instruction sets optimized for serial interfaces and are intended to have simple programs that execute independently of the application to interface with sensors and other peripherals. By freeing the main processor core of direct interface requirements, they can improve performance and often simplify development. In the future, I would expect more and more MCUs to include minion cores among their peripherals.

As the amount of data to be processed and efficiently requirements increase, we should expect to see heterogeneous processing in FPGAs and microcontrollers increasing and be ready to shift our mental programming models to take advantage of the many different paradigms available.

Daniel Casner is a robotics engineer at Anki, co-founder of Robot Garden, hardware start-up adviser, and embedded systems consultant. He is passionate about building clever consumer devices, adding intelligence to objects, and smart buildings or any other cyber-physical system. His specialties include: design for manufacture and salable production; cyber-physical security; reverse engineering; electronics and firmware; signal processing; and prototype development.

This essay appears in Circuit Cellar 301.