Laundry Machine Design Embeds Espressif ESP32 Microcontroller

Espressif Systems has announced that Schulthess Maschinen AG has recently developed a laundry machine with an integrated cashless payment system based on the Espressif Systems ESP32 MCU. Such laundry machines are usually found in buildings with special laundry rooms used by all tenants. Because of the cashless payment system, there’s no longer any need to get hold of the precise amount of coins one needs for a washing cycle.

All the required components are integrated within the “washMaster”. ESP32 is the embedded microcontroller which is responsible for the communication with the machine controller, the radio frequency identification (RFID) reader and the backend system. ESP32 reports the machine-status information, while also managing the price list and handling the machine configuration as well as payments, refunds and balance checks.

According to the company, this is another example of the many advantages that ESP32 has in embedded systems. As a combo Wi-Fi and Bluetooth chip, it is able to maintain a secure and robust connection, while also guaranteeing reliable system function, ultra-low-power consumption and a great level of integration. ESP32 adds priceless functionality and versatility to all the applications in which it is embedded.

Based on the stable performance of the ESP32 modules, Schulthess used the OTA update capability from the very first prototype, which helped throughout the development phases by working reliably all the time. So, customers can now enjoy a complete solution to cashless payment systems for laundry machines. No coins are necessary and neither are any extra personnel costs, due to a sleek automated system.

Espressif Systems |


Odroid-N2 SBC has Hexa-Core Amlogic S922X and $63 to $79 Price

By Eric Brown

Hardkernel announced an “Odroid-N2” SBC with a Cortex-A73 and -A53 based Amlogic S922X SoC plus 2-4GB DDR4, 4x USB 3.0, HDMI 2.1, an audio DAC, and a 40-pin header.

Hardkernel unveiled its open-spec, Ubuntu-ready Odroid-N1 SBC a year ago with a Rockchip RK3399 SoC. Since it was scheduled for June shipment, we included it our reader survey of 116 hacker boards. Yet, just before we published the results, including a #16 ranking for the N1, Hardkernel announced it was shelving the board due to sourcing problems and switching to a similar new board with an unnamed new SoC. The Odroid-N2 would also switch to DDR4 RAM from the previously announced DDR3, which was in short supply.

Odroid-N1 with heatsink (left) and within black case
(click images to enlarge)
The Odroid-N2 will arrive in April about four months later than intended, but with a much lower $63 (2GB RAM) and $79 (4GB) price compared to the original Odroid-N1 goal of “about $110.” The new model has also advanced to a similarly hexa-core, but much faster Amlogic S922X SoC, which was unveiled in September along with the quad-core -A53 Amlogic S905X2 and S905Y2.

Amlogic has yet to post a product page for the 12nm-fabricated S922X, which integrates 4x Cortex-A73 cores instead of the RK3399’s 2x 2.0GHz -A72 cores. The S922X also has 2x -A53 cores that clock to 1.9GHz instead of 4x 1.5GHz -A53 cores on the high-end version of the RK3399 used by the N1. The N2 also moves up to a Mali-G52 GPU with 6x 846MHz execution engines, which the Odroid project benchmarks as 10 percent faster.

Odroid-N2 CPU benchmark comparison (left) and block diagram 
(click images to enlarge)
Hardkernel has posted benchmarks that claim around 20 percent faster CPU performance than the RK3399-driven N1. The inclusion of a substantial metal heatsink and the placement of the SoC and RAM on the bottom of the board enable top speeds “without thermal throttling,” says the Odroid project. With the 4GB version (the only configuration announced for the N1), the N2’s 1320MHz DDR4-RAM is claimed to be 35 percent faster than the N1’s 800MHz DDR3.

Although it may not make much sense to compare the Odroid-N2 to a board that never shipped, it should be noted that the Odroid-N1’s PCIe-based SATA connectors (also found on a few other RK3399 boards) have disappeared. However, you get 4x USB 3.0 host ports instead of a split between 3.0 and 2.0.

Odroid-N2 detail view (see legend farther below)
(click image to enlarge)
The USB ports sit next to a faster GbE port (about 1Gbps) and a 4K-ready HDMI port which is variablly listed as 2.0 and 2.1. For wireless, you’ll need to use one of the USB ports.

Legend for detail view above
(click image to enlarge)
The Odroid-N2 is slightly smaller than the N1 at 90 x 90 x 17mm and has a different design. Several ports such as the micro-USB OTG port and new IR sensor and composite A/V jack appear on the opposite coastline. The A/V jack includes a high-quality audio DAC (384Khz/32bit) with dynamic range, near-100dB SNR, and Total-Harmonic-Distortion lower than 0.006 percent, claims the Odroid project.

The 40-pin expansion header provides 25x GPIO, 2x I2C, SPDIF, and other 3.3V interfaces except for the dual 1.8V ADC signals. The pinout is said to be similar to the Amlogic S905 based Odroid-C2. There’s a wide-range 7.5-20V DC jack, and power consumption is listed as 1.8W idle to 5.5W CPU stress. No operating range was listed, but benchmarks suggest it runs run fine at 35°C.

The Odroid-N2 is available with 64-bit Ubuntu 18.04 LTS with Linux 4.9.152 LTS and Android 9 Pie “with full source code BSP and pre-built image together.” There is no X11 GPU driver and the Mali G52 GPU Linux driver currently works only on the framebuffer, but there’s a hardware-accelerated VPU driver. A Linux Wayland driver and Vulkan capable GPU driver for Android are in the works.

Odroid-N2 in white case (left) and GPIO pinout
(click images to enlarge)
The board ships with 8MB SPI along with a boot select switch and a Petitboot app. It requires removal of any bootable eMMC while you’re making the switch.

Odroid boards, such as the ever popular Odroid-XU4 have usually scored high in our reader surveys due to solid HW/SW quality, vigorous open source support, and a devoted community. The Odroid project recently branched into x86 territory with its Intel Gemini Lake based Odroid-H2.

Specifications listed for the Odroid-N2 include:

  • Processor — Amlogic S922X (4x Cortex-A73 @ 1.8GHz, 2x Cortex-A53 @ 1.9GHz); 12nm fab; Mali-G52 GPU with 6x 846MHz EEs
  • Memory/storage:
    • 2GB or 4GB DDR4 (1320MHz, 2640MT/s) 32-bit RAM
    • eMMC socket with optional 8GB to 128GB
    • MicroSD slot with UHS-1 SDR104 support
    • 8MB SPI flash with boot select switch and Petitboot app
  • Wireless — Optional USB WiFi adapter
  • Networking — Gigabit Ethernet port (Realtek RTL8211F); about 1Gbps
  • Media I/O:
    • HDMI 2.1 port for up to 4K@60Hz with HDR, CEC, EDID
    • Composite video jack with stereo line-out and 384Khz/32bit audio DAC
    • SPDIF audio via 40-pin
  • Other I/O:
    • 4x USB 3.0 host ports (340MB/s typical)
    • Micro-USB 2.0 OTG port (no power)
    • Serial console interface
    • Fan connector
  • Expansion — 40-pin GPIO header (25x GPIO, 2x i2C, 2x ADC, 6x PWM, SPI, UART, SPDIF, various power signals, etc.)
  • Other features — RTC (NXP PCF8563) with battery connector; IR receiver; metal heatsink; 2x LEDs; optional $4 acrylic case
  • Power — 7.5-20V DC jack; 12V/2A adapter recommended; consumption: 1.8W idle to 5.5W stress
  • Dimensions — 90 x 90 x 17mm
  • Operating system — Ubuntu 18.04 LTS with Kernel 4.9.152 LTS and Android 9 Pie BSPs

Further information

The Odroid-N2 will go on sale in late March with shipments beginning in April. Some engineering samples will head out to a lucky few over the next week. Pricing is $63 (2GB RAM) and $79 (4GB) price. More information may be found on Hardkernel’s Odroid-N1 announcement and product page and wiki.

This article originally appeared on on February 13.

Odroid by Hardkernel |

MOSFET Power Modules Target UPS and Energy Storage Needs

Infineon Technologies has launched new devices in its 1,200 V Silicon Carbide (SiC) CoolSiC MOSFET family. The CoolSiC Easy 2B power modules enable engineers to reduce system costs by increasing power density. In addition, they can also lower operational costs significantly. Owing to about 80 % lower switching losses compared to silicon IGBTs, inverter efficiency levels exceeding 99 % can be reached. Because of the specific SiC properties, the same or even higher switching-frequency operation can be realized. This is particularly attractive for fast switching applications such as UPS and energy storage.

The Easy 2B standard package for power modules is characterized by an industry-leading low stray inductance. With a variety of half-bridge, six-pack and booster modules, Infineon offers the largest SiC portfolio in the Easy package on the market. The half-bridge configuration of the CoolSiC Easy 2B can easily be used for building up four- and six-pack-topologies. The new device widens the power range of modules in half-bridge topology with an on-resistance (RDS(ON)) per switch to only 6 mΩ. This is a benchmark performance for devices in Easy 2B housing.

Additionally, the integrated body diode of the CoolSiC MOSFET chip ensures a low-loss freewheeling function without the need for another diode chip. While the NTC temperature sensor facilitates the monitoring of the device, the PressFIT technology reduces assembly time for mounting the device.

The CoolSiC MOSFET Easy 2B modules are available now. Just recently, Infineon launched the first CoolSiC MOSFET six-pack module in the well-established Easy 1B package with an RDS(ON) of 45 mΩ.

Infineon Technologies |

45 V, Zero-Drift Op Amp Provides On-Chip EMI Filtering

Microchip Technology has announced the MCP6V51 zero-drift operational amplifier (op amp). The new device provides ultra-high-precision measurement while minimizing the increasing influence of high-frequency interference by offering a wide operating range and on-chip electromagnetic interference (EMI) filters. The growth of industrial control and factory automation has led to an uptick in the number of sensors that need to be monitored, and the MCP6V51 amplifier is designed to provide accurate, stable data from a variety of sensors.

The self-correcting zero-drift architecture of the MCP6V51 enables ultra-high Direct Current (DC) precision, providing a maximum offset of ±15 microvolts (µV) and only ±36 nanovolts per degree Celsius (nV/°C) of maximum offset drift. Ideal for applications such as factory automation, process control and building automation, the MCP6V51 also supports an extremely wide operating voltage range, from 4.5 V to 45 V.
With the proliferation of wireless sensors and capabilities, high-frequency interference within sensitive analog measurement is becoming a critical consideration. The additional on-chip EMI filtering within the MCP6V51 provides protection from these unwanted and unpredictable interference sources.

Programmable logic controllers and distributed control systems utilized within industrial automation run on a variety of voltage rails, such as 12 V, 24 V and 36 V. The MCP6V51 offers the flexibility to support a wide range of supply voltages and includes overhead to account for supply transients by supporting an operating range up to 45 V.

For evaluation, the 8-Pin SOIC/MSOP/TSSOP/DIP Evaluation Board (Part # SOIC8EV) is a blank PCB that allows the operation of Microchip Technology’s 8-pin devices to be easily evaluated. Each device pin is connected to a pull-up resistor, a pull-down resistor, an in-line resistor, and a loading capacitor. The PCB pads allow through-hole or surface mount connectors to be installed to ease connection to the board. Additional passive component footprints are on the board to allow simple circuits to be implemented.

The MCP6V51 is available now for sampling and volume production in both 5-lead SOT-23 and 8-lead MSOP packages. Prices begin at $0.98 USD per 10,000 units for the SOT-23-5 package.

Microchip Technology |

Next Newsletter: Embedded Boards

Coming to your inbox tomorrow: Circuit Cellar’s Embedded Boards newsletter. Tomorrow’s newsletter content focuses on both standard and non-standard embedded computer boards that ease prototyping efforts and let you smoothly scale up to production volumes.

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

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You’ll get your
Embedded Boards newsletter issue tomorrow.

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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:

Analog & Power. (3/5) 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 (3/12) 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.

IoT Technology Focus. (3/19) 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.

Wi-Fi 6 / Bluetooth Combo Chips Enhance Automotive Infotainment

Cypress Semiconductor has announced a trio of new products, including Wi-Fi / Bluetooth combo chipsets and supporting software serve as application development platforms that enable multiple users to connect and seamlessly stream unique content to as many as 10 mobile devices simultaneously. The new infotainment platforms include a Wi-Fi 6 (802.11ax) and Bluetooth combo solution that features Cypress’ Real Simultaneous Dual Band (RSDB) architecture. RSDB has become the de facto standard for premium connected infotainment experiences, enabling two unique data streams to run at full throughput simultaneously by integrating two complete Wi-Fi subsystems into a single chip. Wi-Fi 6 enables gigabit-level throughput and improves reliability for content streaming to multiple devices at once.
Cypress also added two Wi-Fi 5 (802.11ac) and Bluetooth combo solutions to its portfolio, empowering car makers and automotive system suppliers with a scalable platform solution to address a wide range of vehicles with a uniform software architecture that minimizes development and system integration costs.

According to Cypress, premium infotainment systems require high-throughput, multi-role, concurrent operation to implement wireless mirroring for applications such as Apple CarPlay, Android Auto and Mirrorlink. Cypress’ Wi-Fi and Bluetooth combo solutions meet these needs and also offer simultaneous Wi-Fi Hotspot and content access, and multi-band/multi-radio coexistence for video and Bluetooth audio. The Cypress CYW89650 2×2 plus 2×2 Wi-Fi 6 and Bluetooth 5.0 combo solution delivers more than 1G bps throughput, and the RSDB architecture enables concurrent operation for these use cases in high-performance infotainment systems without audio or video degradation.

The new CYW89459 2×2 Wi-Fi 5 and Bluetooth 5.0 combo with RSDB builds on the success of Cypress’ existing automotive Wi-Fi 5 solutions, enabling more connected devices to the head unit and including emerging features such as WPA3 security, Wi-Fi Location and Wi-Fi Aware. Together with the new cost-effective CYW89373 1×1 Wi-Fi 5 and Bluetooth 5.0 combo, the portfolio provides mass market to luxury class vehicles with advanced wireless performance and medium coexistence management for an uninterrupted entertainment experience.

Cypress’ automotive wireless solutions are fully automotive qualified with AEC-Q100 grade-3 validation. Cypress’ existing solutions have been designed in by numerous top-tier car OEMs and automotive suppliers and are in production vehicles today supporting infotainment and telematics applications such as smartphone screen-mirroring, content streaming and Bluetooth voice connectivity in car kits.

Cypress Semiconductor |



504-W Rated AC-DC Power Modules are Conduction Cooled

TDK has announced its conduction cooled TDK-Lambda PFH500F-28 AC-DC power modules. The power supplies are rated at 28 V,504 W, feature a compact 4” x 2.4” footprint and have optional Read/Write programming and communication through a PMBus interface. These third generation power supplies are ideal for a variety of applications including COTS (Commercial-Off-The-Shelf), power amplifiers, LED displays and test equipment.

The PFH500F-28 series utilizes GaN semiconductors, bridgeless power factor correction, synchronous rectification and digital control, enabling efficiencies of up to 92%. Opto-couplers have been replaced by digital isolators for long term reliability and stability. Accepting an 85 to 265 VAC input, the modules deliver 28V at 18A and can be adjusted from 22.4 to 33.6 V using the trim pin or PMBus interface. Baseplate cooling allows operation at temperatures ranging from -40°C to +100°C. The metal enclosure measures 4” x 2.4” x 0.53” (101.6 mm x 61.0 mm x 13.3mm) and is encapsulated for MIL-STD-810G shock and vibration.

Features and options include a 12 V standby voltage with 200 mA (or 2.4 W) capability, remote on/off, pre-biasing start-up, droop mode current share, a DC Good signal, various protections (OVP, UVP, OCP, OTP) and a PMBus interface. The interface can be used to program (read-write) the output voltage and fault management functions and monitor the unit’s operating status.

The series has been certified to the IEC/UL/CSA/EN 60950-1 safety standards (62368-1 pending) and carries the CE mark for the Low Voltage and RoHS Directives. Input to ground isolation is 2,500 Vac, input to output 3,000 Vac and output to case 1,500 Vdc.

Main Features and Benefits:

  • 4” x 2.4” foot-print
  • High Efficiency – up to 92%
  • PMBus interface
  • Parallel capability (droop mode)

TDK Lambda |


Guitar Video Game Uses PIC32

Realism Revamp

While music-playing video games are fun, their user interfaces tend to leave a lot to be desired. Learn how these two Cornell students designed and built a musical video game that’s interfaced using a custom-built wireless guitar controller. The game is run on a Microchip PIC32 MCU and has a TFT LCD display to show notes that move across the screen toward a strum region.

By Jake Podell and Jonah Wexler

While many popular video games involve playing a musical instrument, the controllers used by the player are not the greatest. These controllers are often made of cheap plastic, and poorly reflect the feeling of playing the real instrument. We have created a fun and competitive musical video game, which is interfaced with using a custom-built wireless guitar controller (Figure 1 and Figure 2). The motivation for the project was to experiment with video game interfaces that simulate the real-world objects that inspired them.

Figure 1
Front of the guitar controller. Note the strings and plectrum.

Figure 2
Back of the guitar controller

The video game is run on a Microchip PIC32 microcontroller [1]. We use a thin-film-transistor LCD display (TFT) to display notes that move across the screen toward a strum region. The user plays notes on a wireless mock guitar, which is built with carbon-impregnated elastic as strings and a conducting plectrum for the guitar pick. The game program running on the PIC32 produces guitar plucks and undertones of the song, while keeping track of the user’s score. The guitar is connected to an Arduino Uno and Bluetooth control center, which communicates wirelessly to the PIC32.

The controller was designed to simulate the natural motion of playing a guitar as closely as possible. We broke down that motion on a real guitar into two parts. First, users select the sound they want to play by holding the appropriate strings down. Second, the users play the sound by strumming the strings. To have a controller that resembled a real guitar, we wanted to abide by those two intuitive motions.

Fret & Strum Circuits

At the top of the guitar controller is the fret board. This is where the users can select the sounds they want to play. Throughout the system, the sound is represented as a nibble (4 bits), so we use 4 strings to select the sound.

Each string works as an active-low push-button. The strings are made of carbon-impregnated elastic, which feels and moves like elastic but is also conductive. Each string was wrapped in 30-gauge copper wire, to ensure solid contact with any conductive surfaces. The strings are each connected to screws that run through the fret board and connect the strings to the fret circuit (Figure 3).

Figure 3
Complete controller circuit schematic (on guitar).

The purpose of the fret circuit is to detect changes in voltage across four lines. Each line is branched off a power rail and connected across a string to an input pin on an Arduino Uno. Current runs from the power rail across each string to its respective input pin, which reads a HIGH signal. To detect a push on the string, we grounded the surface into which the string is pushed. By wrapping the fret board in a grounded conductive pad and pushing the string into the fret board, we are able to ground our signal before it can reach the input pin. When this occurs, the associated pin reads a LOW signal, which is interpreted as a press of the string by our system.

Along with the fret circuit, we needed a way to detect strums. The strum circuit is similar in its use of a copper-wrapped, carbon-impregnated elastic string. The string is connected through the fret board to an input pin on the Arduino, but is not powered. Without any external contact, the pin reads LOW. When voltage is applied to the string, the pin reads HIGH, detecting the strum. To mimic the strumming motion most accurately, we used a guitar pick to apply the voltage to the string. The pick is wrapped in a conductive material (aluminum foil), which is connected to the power rail. Contact of the pick applies voltage to the string, which on a rising edge denotes a strum.

Figure 4
Shown here is a block diagram of the controller signals.

As shown in Figure 4, the direct user interface for the player is the guitar controller. The physical interaction with the guitar is converted to an encoded signal by an Arduino mounted to the back of the guitar. The Arduino Uno polls for a signal that denotes a strum, and then reads the strum pattern across the four strings. The signal is sent over USB serial to a Bluetooth control station, which uses a Python script to broadcast the signal to an Adafruit Bluetooth LE module. The laptop that we used as a Bluetooth control station established a link between the controller and the Bluetooth receiver, and was paramount to the debugging and testing of our system. Finally, the Bluetooth module communicated over UART with the PIC, which interpreted the user’s signal in the context of the game [2].  …

Read the full article in the March 344 issue of Circuit Cellar
(Full article word count: 3271 words; Figure count: 10 Figures.)

Watch the project video here:

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

Antenna Performance Measurement Made Easy

Covering the Basics
by Robert Lacoste

Article appeared in Circuit Cellar October 2017 (Issue 327)

If you’re doing any kind of wireless communications application, that probably means including an antenna in your design. The science of antennas is complex. But here Robert shows how the task of measuring an antenna’s performance is less costly and exotic than you’d think.

Now that wireless communications is ubiquitous, chances are you’ll be using Bluetooth,
Wi-Fi, cellular, LoRa, MiWi or other flavor of wireless interface in your next design. And that means including an antenna. Unfortunately, antenna design is not an easy topic. Even very experienced designers sometimes have had to wrestle with unexpected bad performances by their antennas. Case in point: Google “iPhone 4 antenna problem” and you will get more than 3 million web pages! In a nutshell, Apple tried to integrate a clever antenna in that model that was threaded around the phone. They didn’t anticipate that some users would put their fingers exactly where the antenna was the most sensitive to detuning. Was it a design flaw? Or a mistake by the users? It was hotly debated, but this so-called “Antennagate” probably had significant impact on Apple’s sales for a while.

I already devoted an article to antenna design and impedance matching (“The Darker Side: Antenna Basics”, Circuit Cellar 211, February 2008). Whether you include a standard antenna or design your own, you will never be sure it is working properly until you measure its actual performance. Of course, you could simply evaluate how far the system is working. But how do you go farther if the range is not enough? How do you figure out if the problem is coming from the receiver, the transmitter, propagation conditions or the antenna itself? My personal experience has been that the antenna is very often the culprit. With that in mind, it really is mandatory to measure whether or not an antenna is behaving correctly. Take a seat. This month, I will explain how to easily measure the actual performance of an antenna. You will see that the process is quite easy and that it won’t even need costly or exotic equipment.

Some Antenna Basics
Let’s start with some basics on antennas. First, all passive antennas have the same performance whether transmitting or receiving. For this article, I’ll consider the antenna as transmitting because that’s easier to measure. Let’s consider an antenna that we inject with a given radio frequency power Pconducted into its connector. Where will this power go? First off, impedance matching should be checked. If the impedance of the antenna is not well matched to the impedance of the power generator, then a part of the power will be reflected back to the generator. This will happen in particular when the transmit frequency is not equal to the resonant frequency of the antenna. In such a case, a part of Pconducted will be lost. That is known as mismatch losses: Pavailable= Pconducted – MismatchLosses. While that itself is a very interesting subject, I have already discussed impedance matching in detail in my February 2008 article. I also devoted another article to a closely linked topic: standing waves. Standing waves appear when there is a mismatch. The article is “The Darker Side: Let’s play with standing waves” (Circuit Cellar 271, February 2013).

For the purpose of discussion here, I will for now assume that there isn’t any mismatching—and therefore no mismatch loss. The full Pconducted power is available for the antenna. A significant part of this power will hopefully of course be radiated into space. Let’s call that part Pradiated. Because the antenna is not perfect, Pradiated will for sure be lower than Pavailable. Remember that power is never actually lost or created from nothing. That means the difference Pavailable – Pradiated is dissipated somewhere—meaning either the antenna or its surroundings will warm up a little. This allows to define the first—and an important— performance characteristic of an antenna: power efficiency. By definition, the power efficiency of an antenna is the ratio between Pradiated and Pavailable. If all the available power is radiated by the antenna then its efficiency would be 100%. But in reality, small antennas made with small conductors have low efficiency. Meanwhile, large antennas built using thick and gold-plated conductors will usually have high efficiency.

Now let’s talk about the gain of the antenna. The concept is illustrated in Figure 1. Any antenna has a given radiation pattern, which means it transmits more power in certain directions of space. An antenna which would radiate the same power in any direction is called an isotropic antenna—but those don’t exist except as a concept. Such an isotropic antenna is taken as a reference, and a real antenna is compared to it. Imagine that you take a test receiver and move it around the antenna under test at a constant distance from it. You can find out the direction where the transmitted power is the highest. Then you compare that to the transmitted power of a theoretical isotropic antenna with the same input power. The difference between the two is called the gain of the antenna and is expressed in dBi. dBi is the decibel compared to an isotropic antenna—“i” for isotropic. Remember that a decibel is just the ratio of two powers—expressed using a logarithmic scale: decibel = 10 log (Pout/Pin)

Figure 1
By definition, the gain of an antenna is the difference between its radiated power and the power radiated by an isotropic antenna, measured in the direction where its radiation is maximal.

You may be wondering: How is this gain linked to the efficiency I talked about earlier? The relationship is far from obvious. In fact, the gain of an antenna concerns its directivity. When an antenna radiates a strong signal in a given direction, its gain is high—even if this radiation occurs in a very narrow angle. In contrast, the efficiency is linked to the total radiated power of an antenna. To measure it you would need to evaluate the transmitted power in all directions and sum them all—an operation that mathematicians call an integration. More exactly the total radiated power is the integral of the radiated power over a sphere. Of course, a lower efficiency also implies a lower gain as the total available power is reduced. But a low efficiency antenna can still have high gain. Aren’t you convinced? Consider a huge parabolic antenna—it could have gain of +30 dBi. This means that the radiated power is focused in a very narrow direction. And in that direction a receiver will see a signal 30 dB higher than if using an isotropic antenna. Of course, the antenna is not creating any power. It’s just focusing it, like a lens focuses light. Now add a 20 dB attenuator between the transmitter and the parabolic antenna—dividing the power by 1020/10 = 100). The overall gain will still be a reasonable 30-20=10dBi—even if 99% of the power will be dissipated in the attenuator.

View the full article PDF

March (issue #344) Circuit Cellar Article Materials

Click here for the Circuit Cellar article code archive

p.6: Guitar Video Game Uses PIC32: Realism Revamp, By Jake Podell and Jonah Wexler


[1] PIC32MX250F128B Datasheet:
[2] UART:
[3] Protothreads by Adam Dunkels:
[4] Karplus-Strong basic implementation:
[5] Arduino Uno datasheets:
[6] Adafruit Bluetooth library:
[7] Note frequencies: (link to be fixed) suits/notefreqs.html
[8] Ode to Joy Sheet Music:
[9] Fixed 16 Point Arithmetic:
[10] Karplus-Strong Figure reference:

Bill of Materials
• PIC32
unit price:  $5
• Solderless breadboard
unit price:  $6
unit price:  $28
• Lab Speakers (2)
unit price: lab supplied
• 9V Power Supply
unit price:  $5
• 1/8 inch 2×4 Plywood
unit price:  $7.00
• Adafruit Bluefruit LE UART Friend
unit price:  $17.50
• Arduino Uno
unit price:  $12.00
• Carbon-Impregnated Elastic
unit price:  lab surplus
Total Cost:  $68.50

Adafruit |
Microchip Technology |

Watch the project video here:


p.14: MCU-Based IC Links USB to Legacy PC I/O: Versatile Solution, By Hossam Abdelbaki

Embarcadero Technologies |
FTDI Chip |
Jiangsu Yuheng |
Microchip Technology |
Prolific Technology |
Silicon Labs |

p.20: Smart Pet Collar Uses GPS and Wi-Fi: PIC32-Based Design, By Vidya Ramesh and Vaidehi Garg


[1]  B. Land, “Cornell University ECE4760, Development Boards, PIC32MX250F128B,” December 2017. [Online]. Available:
[2]  Wildlife ACT, “GPS AND VHF TRACKING COLLARS USED FOR WILDLIFE MONITORING,” 17 April 2014. [Online]. Available: [Accessed 25 November 2017]
[3]  A. Dunkels, “Protothreads,” [Online]. Available:
[4]  B. Land, “Cornell University ECE4760, ProtoThreads and Timers, PIC32MX250F128B,” 31 October 2017. [Online]. Available:
[5]  G. Baddeley, “GPS – NMEA sentence information,” 20 July 2001. [Online]. Available:
[6]  J. C. a. H. Liu, “GPS Navigator for Runners,” 2015. [Online]. Available:
[7]  A. X. a. J. C. Adam Chung, “MCU-Based Platform Stabilizer,” Circuit Cellar Magazine, no. #330, pp. 28-33, January 2018.
[8]  B. Land, “Cornell University ECE4760, UART Serial, PIC32MX250F128B,” 2 November 2017. [Online].
[9]  “Arduino/libraries/ESP8266WiFi/,” [Online]. Available:
[10]  “Arduino/libraries/ESP8266WebServer/,” [Online]. Available:
[11]  “WiFiClient(),” [Online]. Available:
[12]  “Google Maps APIs,” 26 March 2018. [Online]. Available:
[13]  “Link AKC Smart Dog Collar,” [Online]. Available:

[14]  B. Land, “Cornell University ECE4760, Development Boards, PIC32MX250F128B,” [Online]. Available:




Part No.

Unit Price


Total Price


Lab Rental





PIC32 Small Development Board

Lab Rental





Microstick II

Lab Rental





Adafruit Huzzah ESP8266 Breakout






Adafruit Ultimate GPS Breakout



Lab Surplus



Adafruit 9-DOF Absolute Orientation IMU Fusion Breakout






7800 mAh Power Bank

All Electronics





Full-size breadboard

Lab Rental





Jumper cables

Lab Rental





Total Cost


Adafruit |
Espressif Systems |
MediaTek Labs |
Microchip Technology |
NodeMcu |

p.26: Formal Flow for Automotive Safety: Bulletproofing Car Design, By Doug Smith

Mentor, a Siemens Company |

p.34: Tailored Solutions Tackle Design Needs for Wearables: Low Power Priorities, By Jeff Child

Analog Devices |
Cypress Semiconductor |
Infineon Technologies |
Maxim Integrated |
Microchip Technology |
Renesas Electronics America |
STMicroelectronics |
Texas Instruments |

p.40: Flex PCB Design Services: Building Boards that Bend, By Jeff Child


p.44: PRODUCT FOCUS 44 Power Supplies for Medical Use: Compliance for Care, By Jeff Child

MINMAX Technology |
Murata Power Solutions |
TDK-Lambda Americas |
XP Power |

p.48: EMBEDDED SYSTEM ESSENTIALS: Side-Channel Power Analysis: Easy Path to Proof, By Colin O’Flynn

NewE Technology |

p.52: THE CONSUMMATE ENGINEER: Cooling Electronic Systems: Beat the Heat, By George Novacek

George Novacek, Product Reliability Part 1 and 2, Circuit Cellar 269, Dec 2012 and
Circuit Cellar 270, Jan 2013

George Novacek, Electronics Cooling Essentials, Circuit Cellar 310, May 2016

George Novacek, Thermoelectric Cooling, Circuit Cellar 336, July 2018 and Circuit Cellar 337, Aug 2018

Digi-Key |
Mouser Electronics |

p.56: PICKING UP MIXED SIGNALS: Impedance Spectroscopy Using the AD5933: From IC to Instrument, By Brian Millier

Digilent PmodIA


Teensy LC MCU board:

Teensyduino Arduino Plug-in:

Microchip 24LC256 I2C EEPROM:

Analog Devices |
Cypress Semiconductor |
Digilent |
Microsoft |

p.68: FROM THE BENCH: Non-Evasive Current Sensor: Pondering Probes, By Jeff Bachiochi

SCT-013-xxx     Split-core current transformer
DeChang Electric Company LTD
Beigaozhuang Village,Haigang district

PIC16F18313        –    Full-Featured, Low Pin Count Microcontroller
Microchip Technology

LM4040-Precision Micropower Shunt Voltage Reference
Texas Instruments

DeChang Electric Company |
Microchip Technology |
Texas Instruments |

p.79: The Future of IoT Connectivity: Cellular Technology’s Role in IoT Market Growth, By Broc Jenkins

Wilson Electronics |

Intel Atom-Based AV Compute Platform Targets Autonomous Cars

By Eric Brown

At CES, Intel unveiled an Intel AV compute platform aimed at autonomous cars. It features a pair of Linux-driven Mobileye EyeQ5 sensor processing chips and a new Intel Atom 3xx4 CPU.

Intel AV’s Responsibility-Sensitive Safety (RSS) model in action (left) and Mobileye EyeQ5 block diagram
(click images to enlarge)
The Intel AV system provides 60 percent greater performance at the same 30 W consumption as Nvidia’s automotive focused Jetson Xavier processor, claims Intel. The Mobileye EyeQ5 processors are each claimed to generate 24 trillion deep learning operations per second (TOPS) at 10 W each. The Atom 3xx4 chip borrows high-end multi-threading and virtualization technologies from Intel’s Xeon processors for running different tasks simultaneously on different systems around the car.

Volkswagen and Nissan have announced plans to use the earlier EyeQ4 processor when it launches later this year. EyeQ5 production won’t begin until 2020, but later this year Intel will release an EyeQ5 Linux SDK with support for OpenCL, deep learning deployment tools, and adaptive AUTOSAR.

This is part of an article that originally appeared on on January 11.

Intel |

Tiny PMICs Offer Efficient High Voltage Automotive Solutions

Maxim Integrated Products has announced power-management ICs (PMICs) that the company claims offers the industry’s smallest solution size and highest efficiency. MAX20004/6/8, MAX20034 and MAX20098 offer low quiescent current, improved noise performance and electromagnetic interference (EMI) mitigation for digital instrument clusters and radio head units.
Maxim’s array of automotive-grade ICs provides many options to manage the DC power as automotive OEMs transition from processors that consume 20 W of power to artificial intelligence platforms that consume as much as 500 W. With a package size of 3.5 mm x 3.75 mm, Maxim’s buck converters offer the industry’s smallest solution size, says the company. Their flip-chip quad-flat no-leads (FCQFN) packaging reduces high-frequency switch node ringing and eliminates bond wires to lower MOSFET switch on-resistance and increase efficiency. Maxim provides pin-compatible parts for four, six and eight amps for flexible power regulation. All of the ICs feature spread-spectrum modulation, high switching frequency, forced pulse-width modulation and skip-mode operation for best-in-class performance.

Maxim’s newest automotive PMICs for high-voltage power applications include:

  • MAX20004, MAX20006 and MAX20008 4 A, 6 A and 8 A high-voltage (40 V tolerant) synchronous buck converters with integrated high-side and low-side MOSFETs, offering the industry’s lowest switch resistance of 38 and 18 mΩ, respectively, for high efficiency. Key advantages of these pin-compatible devices include 25 µA quiescent current, operating input voltages from 3.5 V to 36 V and 93 percent peak efficiency. All are available in a compact 3.5 mm x 3.75 mm, 17-pin side-wettable QFN package that reduces high-frequency switch node and improves efficiency.
  • MAX20098 220 kHz to 2.2 MHz synchronous buck controller for applications with mid- to high-power requirements operating with input voltages from 3.5 V to 36 V (42 V tolerant). For efficiency, this device features a quiescent current of 3.5 µA in skip mode at 3.3 V output along with a 1µA typical shutdown current specification. Its 3 mm x 3 mm side-wettable QFN package reduces solution size, and the IC requires few external components, enabling a two-layer PCB design.
  • MAX20034 220 kHz to 2.2 MHz dual synchronous buck controller for high-voltage applications operating with input voltages from 3.5 V to 36 V (42 V tolerant), where one regulator will operate as a fixed 5 V or 3.3 V output and the other output is adjustable between 1V to 10V. Key efficiency advantages include 17 µA quiescent current in skip mode and 6.5µA typical shutdown current. The device is available in a 5 mm x 5 mm side-wettable QFN package, and it provides up to 2.2 MHz switching frequency to enable smaller external components and total solution size.

Maxim Integrated |


Runtime Security Agent Tailors Itself to Each Linux-based IoT Device

By Eric Brown

Security startup VDOO has launched its ERA (Embedded Runtime Agent), which it claims is the first auto-generated runtime agent designed to offer security protections directly on Linux-based IoT devices. The ERA agent is claimed to offer more optimized and timely protection of IoT devices than is available from typical top-down enterprise security solutions. A runtime agent like ERA is better equipped for securing highly diversified IoT devices, says the Israel-based company.

As explained in this CRN story, VDOO secured $13 million from Dell and other investors a year ago to help produce a growing stable of security software. Its major offering is a Vision security analytics platform, which is integrated with ERA.
Vision is used to scan and analyze the firmware of the device to identify vulnerabilities and provide optimized security recommendations. Vision then auto-generates a security plan that enables the developer to tailor the ERA agent for the device to reduce unnecessary overhead and better protect against specific vulnerabilities.

Available for Linux and Android, with FreeRTOS support in beta, ERA supports Arm, x86, and MIPS devices. Its footprint is less than 1MB and it consumes less than 1 percent of CPU overhead, says VDOO.

The ERA agent can run in a “Prevent” mode that blocks attempted attacks before logging them, or in an “Alert Only” mode that sends alerts about attempted attacks, but without blocking them. VDOO is working on a “Learning” mode that analyzes device behavior in order to automatically suggest the most suitable protection policy.

ERA can protect against zero-day vulnerabilities, man-in-the-middle attacks, and bricking and reverse engineering schemes. The agent can block “malicious modification, theft, and ransoming of user data, device configuration, and binaries,” as well as massive DDoS attacks that use “a botnet, mine Blockchain, or crack passwords hashes,” says VDOO.

The agent can protect against lateral movement exploitation strategies that hijack devices in order to attack other networked devices, says VDOO. The agent has been successful in stopping recent malware including DirtyCOW, Mirai, VPNFilter, Torii, and Chalubo.

ERA is primarily aimed at OEM device manufacturers but can also be used by IT departments to protect existing IoT devices. The software can be added to existing firmware stacks as part of an update. Customers can send locally stored logs to a Syslog/SIEM server or an ELK Stack. They can also define custom whitelists or blacklists.

Further information

The ERA agent is available now at an undisclosed price. More information may be found in VDOO’s ERA announcement and product page.

This article originally appeared on on January 22.


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.(2/26) 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.

Analog & Power. (3/5) 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 (3/12) 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.

i.MX 8M SoC-Based Solution Enables Immersive 3D Audio

NXP Semiconductors has announced its Immersiv3D audio solution for the smart home market. The solution combines NXP software on its i.MX 8M Mini applications processor and will support both Dolby Atmos and DTS:X immersive audio technologies in future devices that integrate the i.MX 8M Mini SoC. The i.MX 8M Mini also brings smart capabilities like voice control to a broader range of consumer devices including soundbars, smart speakers, and AV receivers with the option for adding additional speakers to distribute smart voice control and immersive audio throughout the home.

TVs and audio systems are becoming more advanced thanks in large part to the development of Dolby Atmos and DTS:X. Both technologies are a leap forward from surround sound and transport listeners with moving audio that fills the room and flows all around them. Listeners will feel like they’re inside the action as the sounds of people, places, thing, and music come alive with breathtaking realism. NXP’s Immersiv3D audio solution was designed to enable OEMs to bring to market affordable consumer audio devices capable of supporting Dolby Atmos and DTS:X in their next-generation devices.

Conventional design approaches to audio systems use Digital Signal Processors (DSPs) to deliver complex, controlled and low-latency audio processing to enable audio and video synchronization. But Traditional embedded systems have evolved over time, and today they are capable of processing the latest 3D audio formats, but audio systems need to be designed to take advantage of today’s advanced processor cores. In conjunction with the NXP i.MX 8M family of processors, the Immersiv3D audio solution introduces an advanced approach that features scalable audio processing integration into the SoC Arm cores. This approach eliminates the need for expensive discrete DSPs, and also once-proprietary DSP design foundations, to embrace licensable cores.

The solution delivers high-end audio features such as immersive multi-channel audio playback, natural language processing and voice capabilities to fit today’s digitally savvy connected consumer. The NXP Immersiv3D audio solution gives audio developers, designers and integrators a leap forward to add intelligence and Artificial Intelligence (AI) functionality while reducing cost. This includes development of enhancements like selective noise canceling where only certain sound elements are removed like car traffic or speech processing like changing speaker dialect or languages.

The solution introduces an easy-to-use, low-cost enablement for voice capability expansion. Audio systems built using NXP’s Immersiv3D with the i.MX 8M Mini applications processor will give consumers the flexibility to add different audio speakers, regardless of brand, to stream simultaneous and synchronized audio with voice control from their systems.

NXP showcased its i.MX applications processor family including Immersiv3D at the CES 2019 show.

NXP Semiconductors |