Capacitive vs. Inductive Sensing

Touch Trade-Offs

Touch sensing has become an indispensable technology across a wide range of embedded systems. In this article, Nishant discusses capacitive sensing and inductive sensing, each in the context of their use in embedded applications. He then explores the trade-offs between the two technologies, and why inductive sensing is preferred over capacitive sensing in some use cases.

By Nishant Mittal

Touch sensing was first implemented using resistive sensing technology. But resistive sensing had a number of disadvantages, including low sensitivity, false triggering and shorter operating life. All of that discouraged its use and led to its eventual downfall in the market.

Today whenever people talk about touch sensing, they’re usually referring to capacitive sensing. Capacitive sensing has proven to be robust not only in a normal environmental use cases but also underwater, thanks to its water-resistant capabilities. As with any technology, capacitive sensing comes with a new set of disadvantages. These disadvantages tend to more application-specific. That situation opened the door for the advent of inductive sensing technology.

In this article, we’ll discuss capacitive sensing for embedded applications and how it can be used in various applications. We will then explore the use of inductive sensing in embedded products and why inductive sensing is preferred over capacitive sensing in some use cases. Finally, we’ll compare the advantages of inductive sensing over capacitive sensing in these applications.

Capacitive Sensing for Embedded

Capacitive sensing operates on the principle of monitoring the change in parasitic capacitance due to a finger touch (Figure 1). Capacitive sensing has been used primarily in two different forms: self-capacitance and mutual-capacitance. In self-capacitance mode, the net capacitance due to a finger touch and board capacitance is additive. This capacitance includes PCB traces and PCB materials like FR4, which has more capacitance compared to Flex materials and many similar dielectrics. Self-capacitance mode is useful in general touch application like buttons for touch-and-respond applications. In contrast, mutual capacitance is well-suited for applications involving more complex sensing such as gestures, multi-touch and sliders.

FIGURE 1
Capacitive sensing technique

Mutual capacitance sensing uses two different lines: TX(Transmitter) and RX(Receiver). The Transmitter sends a PWM signal with respect to the system VDD and GND. The Receiver detects the amount of charge received on the RX electrode.

One of the difficult use cases of capacitive sensing is that it cannot operate perfectly underwater. It also requires relatively strict design guidelines to be followed for error-free operation. Capacitive sensing performance is also impacted by nearby LEDs and power lines on PCBs. Implementing auto-tuning with variation in trace capacitance, variation in capacitive sensing buttons and different slider sizes and shapes all require different designs. Implementation challenges in industrial applications include using capacitive sensing with thicker glass material (display glass) and meeting capacitive sensor sensitivity requirements with those types of materials.

Inductive Sensing for Embedded

Inductive sensing enables the next-generation of touch technology in applications involving metal-over-touch use cases such as in automotive, industrial and many embedded and IoT applications. Inductive sensing is based on the principle of electromagnetic coupling, between a coil and the target (Figure 2). When a metal target comes closer to the coil, its magnetic field is obstructed and it passes through the metal target before coupling to its origin. This phenomenon causes some energy to get transferred to the metal target—referred to as eddy current—that causes a circular magnetic field. Eddy current induces a reverse magnetic field, in turn leading to a reduction in inductance.

FIGURE 2
Inductive sensing technique [1]

To cause the resonant frequency to occur, a capacitor is added in parallel to the coil to cause the LC tank circuit. As the inductance starts reducing, the frequency shifts upward changing the amplitude throughout. In contrast to a capacitive sensor, inductive sensing is able to operate reliably in the presence of water thanks to the removal of a dielectric from the sensor. This advantage brings inductive sensing touch sensing to a wide range of applications that involve liquids such as underwater equipment, flow meters, RPM detection, medical instruments and many others. Inductive sensing also supports biomedical applications. In general applications, inductive sensing enables replacement of mechanical switches and proximity sensing of metal objects. For example, in automotive applications, inductive sensing can be used to replace mechanical handles as well as detect car proximity. Some of these examples will be discussed in detail later..

Read the full article in the May 346 issue of Circuit Cellar
(Full article word count: 1842 words; Figure count: 6 Figures.)

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5 V MCU Family Provides Water Tolerant Touch Integration

NXP Semiconductor has announced its 5 V KE1xZ family of MCUs. Based on the Arm Cortex-M0+ core, the MCUs are suited for embedded control systems in harsh electrical environments and provide an integrated CAN controller and capacitive touch from 32 KB flash. Designed for a wide range of industrial applications, the KE1xZ family offers mixed-signal integration across a range of compact memory variants. The 1-MS/s ADC and FlexTimer modules, combined with NXP’s Freemaster software tools library and Motor Control Application Tuning plugin (MCAT) enable designs of Brushless DC (BLDC) and other motor-control systems.

NXP’s KE1xZ MCU family offers advanced noise immunity, water-tolerant touch and low-power wake-on-touch operation—essential features for the strict electromagnetic compatibility (EMC) standards of the industrial and home appliance markets. NXP’s touch IP, combined with software and tools provide a high level of stability, accuracy and ease of use, with continued responsiveness and functionality through wet conditions. It can sustain 10 V in conducted noise, in alignment with International Electrotechnical Commission (IEC) 6100-4-6 test level 3.

Additional KE1xZ MCU features:

  • Internal 48MHz internal reference clock with 1% accuracy over full operating range
  • Boot ROM with built in bootloader and 128-bit unique device identifier (UID)
  • ADC self-calibration feature
  • Flash Access Control (FAC)
  • Cyclic Redundancy Check (CRC) generator module
  • Internal watchdog (WDOG) with independent clock source and external watchdog monitor (EWM)
  • On-chip clock loss monitoring
  • IEC 60730 Class B safety certification
  • LQFP package with 48- and 44-pin options

The KE1xZ MCU family will be available globally in March 2019 from NXP and its distribution partners with a suggested resale price from $0.79 at 10,000-unit quantities. NXP enables developers through its MCUXpresso software and tools ecosystem, along with its FRDM-KE15Z and FRDM-TOUCH development platforms (see image above), with respective suggested resale prices of $35 and $15. Third-party support is enabled from the broad ARM ecosystem.

NXP Semiconductor | www.nxp.com

 

May Circuit Cellar: Sneak Preview

The May issue of Circuit Cellar magazine is out next week!. We’ve been hard at work laying the foundation and nailing the beams together with a sturdy selection of  embedded electronics articles just for you. We’ll soon be inviting you inside this 84-page magazine.

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EMBEDDED COMPUTING AT WORK

Technologies for Digital Signage
Digital signage ranks among the most dynamic areas of today’s embedded computing space. Makers of digital signage players, board-level products and other technologies continue to roll out new solutions for implementing powerful digital signage systems. Circuit Cellar Chief Editor Jeff Child looks at the latest technology trends and product developments in digital signage.

PC/104 and PC/104 Family Boards
PC/104 has come a long way since its inception over 25 ago. With its roots in ISA-bus PC technology, PC/104 evolved through the era of PCI and PCI Express by spinning off its wider family of follow on versions including PC/104-Plus, PCI-104, PCIe/104 and PCI/104-Express. This Product Focus section updates readers on these technology trends and provides a product gallery of representative PC/104 and PC/104-family boards.

TOOLS & TECHNIQUES FOR EMBEDDED ENGINEERING

Code Analysis Tools
Today it’s not uncommon for embedded devices to have millions of lines of software code. Code analysis tools have kept pace with these demands making it easier for embedded developers to analyze, debug and verify complex embedded software. Circuit Cellar Chief Editor Jeff Child explores the latest technology trends and product developments in code analysis tools.

Transistor Basics
In this day and age of highly integrated ICs, what is the relevance of the lone, discrete transistor? It’s true that most embedded systems can be solved by chip level solutions. But electronic component vendors do still make and sell individual transistors because there’s still a market for them. In this article, Stuart Ball reviews some important basics about transistors and how you can use them in your embedded system design.

Pressure Sensors
Over the years, George Novacek has done articles examining numerous types of sensors that measure various physical aspects of our world. But one measurement type he’s not yet discussed in the past is pressure. Here, George looks at pressure sensors in the context of using them in an electronic monitoring or control system. The story looks at the math, physics and technology associated with pressure sensors.

MICROCONTROLLERS DO IT ALL

Robotic Arm Plays Beer Pong
Simulating human body motion is a key concept in robotics development. With that in mind, learn how these Cornell graduates Daniel Fayad, Justin Choi and Harrison Hyundong Chang accurately simulate the movement of a human arm on a small-sized robotic arm. The Microchip PIC32 MCU-based system enables the motion-controlled, 3-DoF robotic arm to take a user’s throwing motion as a reference to its own throw. In this way, they created a robotic arm that can throw a ping pong ball and thus play beer pong.

Fancy Filtering with the Teensy 3.6
Signal filtering entails some tricky tradeoffs. A fast MCU that provides hardware-based floating-point capability eases some of those tradeoffs. In the past, Brian Millier has used the Arm-based Teensy MCU modules to serve meet those needs. In this article, Brian taps the Teensy 3.6 Arm MCU module to perform real-time audio FFT-convolution filtering.

Real-Time Stock Monitoring Using an MCU
With today’s technology, even very simple microcontroller-based devices can fetch and display data from the Internet. Learn how Cornell graduates David Valley and Saelig Khatta built a system using that can track stock prices in real-time and display them conveniently on an LCD screen. For the design, they used an Espressif Systems ESP8266 Wi-Fi module controlled by a Microchip PIC32 MCU. Our fun little device fetches chosen stock prices in real-time and displays them on a screen.

… AND MORE FROM OUR EXPERT COLUMNISTS

Attacking USB Gear with EMFI
Many products use USB, but have you ever considered there may be a critical security vulnerability lurking in your USB stack? In this article, Colin O’Flynn walks you through on example product that could be broken using electromagnetic fault injection (EMFI) to perform this attack without even removing the device enclosure.

An Itty Bitty Education
There’s no doubt that we’re living in a golden age when it comes to easily available and affordable development kits for fun and education. With that in mind, Jeff Bachiochi shares his experiences programming and playing with the Itty Bitty Buggy from Microduino. Using the product, you can build combine LEGO-compatible building blocks into mobile robots controlled via Bluetooth using your cellphone.

Capacitive Touch-Key MCUs Enable 2D/3D Gesture Control

Renesas Electronics has introduced two touch-free user interface (UI) solutions for simplifying the design of 2D and 3D control-based applications. Based on Renesas’ capacitive sensor microcontrollers, the new solutions support the development of UI that allows users to operate home appliances, as well as industrial and OA equipment without touching the devices. The UI solutions make it possible for appliance and equipment manufacturers to quickly develop touch-free interfaces that increase the added-value of their products in terms of both equipment convenience and design.
There are a variety of situations where touch-free operation is advantageous, such as when the users’ hands are wet, when the controls are out of reach, or when it is not safe for the user to touch the controls. Renesas new touch-free UI, for example in the kitchen, users could adjust water temperature and flow rate through hand gestures near the faucets or adjust stove fan operation by holding a hand over the hood. The touch-free UI solutions allow customers to easily implement these interfaces in their embedded equipment. The reference designs are available for download.

The new gesture solutions detect motion in a 2D coordinate system and in 3D space, respectively. With both solutions, Renesas provides design materials (circuit diagrams, board design data files and parts lists) that form the reference hardware for the capacitive touch-key MCU, as well as coordinate calculation middleware, sample programs, application notes and an evaluation tool for monitoring the detected coordinates. The touch-free UI solutions have passed class B testing for the IEC 61000 4-3 level 3 and 4-6 level 3 noise immunity standards, and can achieve stable operation.

The 3D gesture solution is available in three different sizes and can be selected based on the application:

  • Standard version (160 × 160 × 100 mm) with RX231 MCU
  • Miniature version (80 × 80 × 80 mm) with RX130 MCU
  • Slim version (100 × 100 × 20 mm) with RX130 MCU for additional space saving

Renesas Electronics | www.renesas.com

 

Low-Power Wireless MCUs Provide Real-Time Performance

STMicroelectronics (ST) has announced its latest Bluetooth offering, its STM32WBx5 dual-core wireless MCUs. The devices come with Bluetooth 5, OpenThread and ZigBee 3.0 connectivity combined with ultra-low-power performance. Fusing features of ST’s STM32L4 Arm Cortex-M4 MCUs and in-house radio managed by a dedicated Cortex-M0+, the STM32WBx5 is power-conscious yet capable of concurrent wireless-protocol and real-time application execution. It is well suited to remote sensors, wearable trackers, building automation controllers, computer peripherals, drones and other IoT devices.
Security features of the STM32WBx5 MCUs include Customer Key Storage (CKS), Public Key Authorization (PKA), and encryption engines for the radio MAC and upper layers. The MCUs have up to 1 MB of on-chip flash and a Quad-SPI port for efficient connection to external memory, if needed. Additional features include crystal-less Full-Speed USB, 32 MHz RF oscillator with trimming capacitors, a touch-sense controller, LCD controller, analog peripherals and multiple timers and watchdogs. The balun for antenna connection is also integrated.

Leveraging ultra-low-power technologies of the STM32L4 line, STM32WBx5 MCUs feature multiple power-saving modes including 13 nA shutdown mode, adaptive voltage scaling, and the adaptive real-time (ART) accelerator to maximize energy efficiency and ensure long-lasting performance in self-powered applications. The integrated radio transmitter is optimized for high RF performance and low power consumption to maximize battery runtime. The RF output power is programmable up to +6 dBm in 1 dB increments, and the MCU draws only 5.2 mA when transmitting at 0 dB. Receive sensitivity is -96 dBm for BLE communication at 1mbps. Designed for a link budget of 102 dB, the radio ensures robust communication over long connection distances and includes support for an external Power Amplifier (PA).

STMicroelectronics | www.st.com

 

PIC MCU Development Board for Cloud IoT Core

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

The board includes:

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

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

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

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

Microchip Technology | www.microchip.com

Low-Power Bluetooth MCUs Deliver Mesh Networking

Cypress Semiconductor has announced it is sampling two low-power, dual-mode Bluetooth 5.0 and Bluetooth Low Energy (BLE) MCUs that include support for Bluetooth mesh networking for the Internet of Things (IoT). The new CYW20819 and CYW20820 MCUs each provide simultaneous Bluetooth 5.0 audio and BLE connections.

The CYW20819 Bluetooth/BLE MCU has the ability to maintain Serial Port Profile (SPP) protocol connections and Bluetooth mesh connections simultaneously. The CYW20820 offers the same features and integrates a power amplifier (PA) with up to 10 dBm output power for long-range applications up to 400 m and whole-home coverage. This provides classic Bluetooth tablet and smartphone connections while enabling a low-power, standards-compliant mesh network for sensor-based smart home or enterprise applications.

Both MCUs embed the Arm Cortex-M4 core. It enables operation at 60% lower active power for connected 200-ms beacons compared to current solutions—delivering up to 123 days of battery life from a CR2032 coin cell battery. Previously, users needed to be in the immediate vicinity of a Bluetooth device to control it without an added hub. Using Bluetooth mesh networking technology, combined with the high-performance integrated PA in the CYW20820, the devices within a network can communicate with each other.

Cypress Semiconductor | www.cypress.com

MCU-Based Solution is Qualified with Alexa Voice Service

NXP Semiconductors has unveiled an MCU based voice control solution qualified with Amazon’s Alexa Voice Service (AVS). This enables original equipment manufacturers (OEMs) to quickly, easily and inexpensively add voice control to their products, giving their customers access to rich voice experiences with Alexa. Built on an NXP i.MX RT crossover platform, this MCU-based AVS solution enables low latency, far-field, “wake word” detection; embeds all necessary digital signal processing capabilities; runs on Amazon FreeRTOS; and includes an Alexa client application.
This MCU-based AVS solution provides OEMs with a self-contained, turnkey offering that enables them to quickly add Alexa to their products. It includes the MCU, the TFA9894D smart audio amplifier, optional A71CH secure element and comes with fully integrated software. It also features noise suppression, echo cancellation, beam forming and barge-in capabilities that enable use in acoustically difficult environments.

NXP offers at its Mougins, Sophia-Antipolis facilities a product testing service for Alexa Built-in products, available to its customers desiring to test their devices before submitting to Amazon for final evaluation. If a customer’s product supports music and/or is far-field enabled and uses a “wake word” to initiate interactions with Alexa, additional testing is required prior to submitting products to Amazon for evaluation. This is where Pro-Support Audio Voice Services helps to complete the self-test checklists.

NXP Semiconductors | www.nxp.com

 

IoT Monitoring System for Commercial Fridges

Using LoRa Technology

IoT implementations can take many shapes and forms. Learn how these four Camosun College students developed a system to monitor all the refrigeration units in a commercial kitchen simultaneously. The system uses Microchip PIC MCU-based monitoring units and wireless communication leveraging the LoRa wireless protocol.

By Tyler Canton, Akio Yasu, Trevor Ford and Luke Vinden

In 2017, the commercial food service industry created an estimated 14.6 million wet tons of food in the United States [1]. The second leading cause of food waste in commercial food service, next to overproduction, is product loss due to defects in product quality and/or equipment failure [2].

While one of our team members was working as the chef of a hotel in Vancouver, more than once he’d arrive at work to find that the hotel’s refrigeration equipment had failed overnight or over the weekend, and that thousands of dollars of food had become unusable due to being stored at unsafe temperatures. He always saw this as an unnecessary loss—especially because the establishment had multiple refrigeration units and ample space to move product around. In this IoT age, this is clearly a preventable problem.

For our Electronics & Computer Engineering Technologist Capstone project, we set forth to design a commercial refrigeration monitoring system that would concurrently monitor all the units in an establishment, and alert the chefs or managers when their product was not being stored safely. This system would also allow the chef to check in on his/her product at any time for peace of mind (Figure 1).

Figure 1
This was the first picture we took of our finished project assembled. This SLA printed enclosure houses our 10.1″ LCD screen, a Raspberry Pi Model 3B and custom designed PCB.

We began with some simple range testing using RFM95W LoRa modules from RF Solutions, to see if we could reliably transmit data from inside a steel box (a refrigerator), up several flights of stairs, through concrete walls, with electrical noise and the most disruptive interference: hollering chefs. It is common for commercial kitchens to feel like a cellular blackout zone, so reliable communication would be essential to our system’s success.

System Overview

We designed our main unit to be powered and controlled by a Raspberry Pi 3B (RPi) board. The RPi communicates with an RFM95W LoRa transceiver using Serial Peripheral Interface (SPI). This unit receives temperature data from our satellite units, and displays the temperatures on a 10.1″ LCD screen from Waveshare. A block diagram of the system is shown in Figure 2. We decided to go with Node-RED flow-based programming tool to design our GUI. This main unit is also responsible for logging the data online to a Google Form. We also used Node-RED’s “email” nodes to alert the users when their product is stored at unsafe temperatures. In the future, we plan to design an app that can notify the user via push notifications. This is not the ideal system for the type of user that at any time has 1,000+ emails in their inbox, but for our target user who won’t allow more than 3 or 4 to pile up it has worked fine.

Figure 2
The main unit can receive temperature data from as many satellite units as required. Data are stored locally on the Raspberry Pi 3B, displayed using a GUI designed by Node-RED and logged online via Google Sheets.

We designed an individual prototype (Figure 3) for each satellite monitoring unit, to measure the equipment’s temperature and periodically transmit the data to a centralized main unit through LoRa communication. The units were intended to operate at least a year on a single battery charge. These satellites, controlled by a Microchip Technology PIC24FJ64GA704 microcontroller (MCU), were designed with an internal Maxim Integrated DS18B20 digital sensor (TO-92 package) and an optional external Maxim

Figure 3
This enclosure houses the electronics responsible for monitoring the temperatures and transmitting to the main unit. These were 3D printed on Ultimaker 3 printers.

Integrated DS18B20 (waterproof stainless steel tube package) to measure the temperature using the serial 1-Wire interface.

Hardware

All our boards were designed using Altium Designer 2017 and manufactured by JLCPCB. We highly recommend JLCPCB for PCB manufacturing. On a Tuesday we submitted our order to the website, and the finished PCB’s were manufactured, shipped, and delivered within a week. We were amazed by the turnaround time and the quality of the boards we received for the price ($2 USD / 10 PCB).

Figure 4
The main unit PCB’s role is simply to allow the devices to communicate with each other. This includes the RFM95W LoRa transceivers, RPi, LCD screen and a small fan

Main Unit Hardware: As shown in Figure 4, our main board’s purpose is communicating with the RPi and the LCD. We first had to select an LCD display for the main unit. This was an important decision, as it was the primary human interface device (HID) between the system and its user. We wanted a display that was around 10″—a good compromise between physical size and readability. Shortly after beginning our search, we learned that displays between 7″ and 19″ are not only significantly more difficult to come by, but also significantly more expensive. Thankfully, we managed to source a 10.1″ display that met our budget from robotshop.com. On the back of the display was a set of female header pins designed to interface with the first 26 pins of the RPi’s GPIO pins. The only problem with the display was that we needed access to those same GPIO pins to interface with the rest of our peripherals.

Figure 5
Our main board, labeled Mr. Therm, was designed to attach directly to the LCD screen headers. RPi pins 1-26 share the same connectivity as the main board and the LCD.

We initially planned on fixing this problem by placing our circuit board between the RPi and the display, creating a three-board-stack. Upon delivery and initial inspection of the display, however, we noticed an undocumented footprint that was connected to all the same nets directly beneath the female headers. We quickly decided to abandon the idea of the three-board-stack and decided instead to connect our main board to that unused footprint in the same way the RPi connects to display (Figure 5). This enabled us to interface all three boards, while maintaining a relatively thin profile. The main board connects four separate components to the rest of the circuit. It connects the RFM95W transceiver to the RPi, front panel buttons, power supply and a small fan.

Read the full article in the April 345 issue of Circuit Cellar
(Full article word count: 3378 words; Figure count: 11 Figures.)

Don’t miss out on upcoming issues of Circuit Cellar. Subscribe today!

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.

BLE Multicore MCUs Embed Arm Cortex M33 CPU

Dialog Semiconductor has announced its SmartBond DA1469x family of Bluetooth low energy SoCs, a range of multi-core MCUs for wireless connectivity. The devices’ three integrated cores have each been carefully chosen for their capabilities to sense, process and communicate between connected devices, says Dialog. To provide the devices’ processing power, the DA1469x product family is the first wireless MCU in production with a dedicated application processor based on the Arm Cortex-M33 CPU, according to Dialog.

The M33 is aimed at compute intensive applications, such as high-end fitness trackers, advanced smart home devices and virtual reality game controllers. The DA1469x devices have a new integrated radio that offers double the range compared to its predecessor together with an Arm Cortex-M0+ based software-programmable packet engine that implements protocols and provides full flexibility for wireless communication.

On the connectivity front, an emerging application is for manufacturers to deploy accurate positioning through the Angle of Arrival and Angle of Departure features of the newly introduced Bluetooth 5.1 standard. With its world-class radio front end performance and configurable protocol engine, the DA1469x complies with this new version of the standard and opens new opportunities for devices that require accurate indoor positioning such as building access and remote keyless entry systems.

To enhance the sensing functionality of the DA1469x, the M33 application processor and M0+ protocol engine is complemented with a Sensor Node Controller (SNC), which is based on a programmable micro-DSP that runs autonomously and independently processes data from the sensors connected to its digital and analog interfaces, waking the application processor only when needed. In addition to this power-saving feature, a state-of-the-art Power Management Unit (PMU) provides best-in-class power management by controlling the different processing cores and only activating them as needed.

The SoCs feature up to 144 DMIPS, 512 KB of RAM, memory protection, a floating-point unit, a dedicated crypto engine to enable end-to-end security and expandable memories, ensuring a wide range of advanced smart device applications can be implemented using the chipset family and supporting a range of key value-add interfaces to extend functionality even further.

The PMU also provides three regulated power rails and one LDO output to supply external system components, removing the requirement of a separate power management IC (PMIC). Additionally, the DA169x product family come equipped with a range of key value-add interfaces including a display driver, an audio interface, USB, a high-accuracy ADC, a haptic driver capable of driving both ERM and LRA motors as well as a programmable stepping motor controller.

Developers working with the DA1469x product family can make use of Dialog’s software development suite – SmartSnippets – which gives them the tools they need to develop best-in-class applications on the new MCUs. The DA1469x variants will start volume production in the first half of 2019. Samples and development kits are available now.

Dialog Semiconductor | www.dialog-semiconductor.com

 

April Circuit Cellar: Sneak Preview

The April issue of Circuit Cellar magazine is out next week (March 20th)!. We’ve worked hard to cook up a tasty selection of in-depth embedded electronics articles just for you. We’ll be serving them up to in our 84-page magazine.

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

VIDEO AND DISPLAY TECHNOLOGIES IN ACTION

Video Technology in Drones
Because video is the main mission of the majority of commercial drones, video technology has become a center of gravity in today’s drone design decisions. The topic covers everything including single-chip video processing, 4k HD video capture, image stabilization, complex board-level video processing, drone-mounted cameras, hybrid IR/video camera and mesh-networks. In this article, Circuit Cellar’s Editor-in-Chief, Jeff Child, looks at the technology and trends in video technology for drones.

Building an All-in-One Serial Terminal
Many embedded systems require as least some sort of human interface. While Jeff Bachiochi was researching alternatives to mechanical keypads, he came across the touchscreen display products from 4D Systems. He chose their inexpensive, low-power 2.4-inch, resistive touch screen as the basis for his display subsystem project. He makes use of the display’s Espressif Systems ESP8266 processor and Arduino IDE support to turn the display module into a serial terminal with a serial TTL connection to other equipment.

MICROCONTROLLERS ARE EVERYWHERE

Product Focus: 32-Bit Microcontrollers
As the workhorse of today’s embedded systems, 32-bit microcontrollers serve a wide variety of embedded applications-including the IoT. MCU vendors continue to add more connectivity, security and I/O functionality to their 32-bit product families. This Product Focus section updates readers on these trends and provides a product album of representative 32-bit MCU products.

Build a PIC32-Based Recording Studio
In this project article, learn how Cornell students Radhika Chinni, Brandon Quinlan, Raymond Xu built a miniature recording studio using the Microchip PIC32. It can be used as an electric keyboard with the additional functionality of recording and playing back multiple layers of sounds. There is also a microphone that the user can use to make custom recordings.

WONDERFUL WORLD OF WIRELESS

Low-Power Wireless Comms
The growth in demand for IoT solutions has fueled the need for products and technology to do wireless communication from low-power edge devices. Using technologies including Bluetooth Low-Energy (BLE), wireless radio frequency technology (LoRa) and others, embedded system developers are searching for ways to get efficient IoT connectivity while drawing as little power as possible. Circuit Cellar Chief Editor Jeff Child explores the latest technology trends and product developments in low-power wireless communications.

Bluetooth Mesh (Part 2)
Continuing his article series on Bluetooth mesh, this month Bob Japenga looks at the provisioning process required to get a device onto a Bluetooth mesh network. Then he examines two application examples and evaluates the various options for each example.

Build a Prescription Reminder
Pharmaceuticals prescribed by physicians are important to patients both old and young. But these medications will only do their job if taken according to a proper schedule. In this article, Devlin Gualtieri describes his Raspberry-Rx Prescription Reminder project, a network-accessible, the Wi-Fi connected, Raspberry Pi-based device that alerts a person when a particular medication should be administered. It also keeps a log of the actual times when medications were administered.

ENGINEERING TIPS, TRICKS AND TECHNIQUES

The Art of Current Probing
In his February column, Robert Lacoste talked about oscilloscope probes—or more specifically, voltage measurement probes. He explained how selecting the correct probe for a given measurement, and using it as it properly, is as important as having a good scope. In this article, Robert continues the discussion with another common measurement task: Accurately measuring current using an oscilloscope.

Software Engineering
There’s no doubt that achieving high software quality is human-driven endeavor. No amount of automated code development can substitute for best practices. A great tool for such efforts is the IEEE Computer Society’s Guide to the Software Engineering Body of Knowledge. In this article, George Novacek discusses some highlights of this resource, and why he has frequently consulted this document when preparing development plans.

HV Differential Probe
A high-voltage differential probe is a critical piece of test equipment for anyone who wants to safely examine high voltage signals on a standard oscilloscope. In his article, Andrew Levido describes his design of a high-voltage differential probe with features similar to commercial devices, but at a considerably lower cost. It uses just three op amps in a classic instrumentation amplifier configuration and provides a great exercise in precision analog design.

Infineon, Xilinx and Xylon Team Up for Safety-Critical MCU Effort

Infineon Technologies has announced an effort with Xilinx and Xylon to produce a new Xylon IP core called logiHSSL. It enables high-speed communication between Infineon’s AURIX TC2xx and TC3xx microcontrollers and Xilinx’ SoC, MPSoC and FPGA devices via the Infineon High Speed Serial Link (HSSL). This serial link supports baudrates of up to 320 Mbaud at a net payload data-rate of up to 84%. The HSSL is an Infineon native interface, low-cost in regards to pin-count because it requires only five pins-–-two LVDS with two pins each and one CLK pin. So far, the HSSL interface is used to exchange data between AURIX devices and customer ASICs for performance or functional extension.

Now, the new IP core will allow system developers to combine safety and security provided by AURIX with the wide range of functional possibilities brought to the table by the Xilinx devices. Linked devices can access and control each other’s internal and connected resources through the HSSL.

To support development activities the partners are offering a starter kit. It includes a Xilinx evaluation kit, an Infineon AURIX evaluation board and a Xylon FMC board. Kit deliverables include the reference design with the test software application, Xylon’s logicBRICKS evaluation licenses, documentation and technical support.

The new IP core and the development kit will be available this month (March 2019).

Infineon Technologies | www.infineon.com
Xilinx | www.xilinx.com
Xylon | www.logicbricks.com

High-Temp Motor Control is Target for 32-Bit MCU Offerings

Renesas Electronics has announced the expansion of its RX24T and RX24U Groups of 32-bit MCUs to include new high-temperature-tolerant models for motor-control applications that require an expanded operating temperature range. The new RX24T G Version and RX24U G Version support operating temperatures ranging from −40°C to +105°C, while maintaining the high speed, high functionality and energy efficiency of the RX24T and RX24U MCUs.
As device form factors shrink, the heat challenge is growing for motor-control applications. In industrial machinery and office equipment, as well as home appliances that handle hot air and heated water, circuit boards are increasingly being mounted in high-temperature locations. In the case of home appliances such as dishwashers or induction hotplates in particular, demand for designs with larger interior capacity or heating areas is increasing, which restricts the space available for circuit boards.

The resulting shift toward circuit board design with a smaller surface area addresses the space constraints but also reduces the board’s capacity to disperse heat, causing the circuit board itself to become quite hot. To address these application needs, Renesas is adding new high-temperature-tolerant products to its MCU lineup that can operate in high-temperature spaces and on hot circuit boards. The new devices will provide greater flexibility for designers of products that operate in high-temperature environments, enabling the trend toward more compact devices to advance.

Software can be developed using the RX24T and RX24U CPU cards combined with the 24 V Motor Control Evaluation Kit which enables developers to create motor control applications in less time. The 32-bit RX24T and RX24U features a maximum operating frequency of 80 MHz. It is equipped with peripheral functions for motor control such as timers, A/D converter, and analog circuits that enable efficient control of two brushless DC motors by a single chip. Renesas has shipped 10 million units of the popular RX24T and RX24U Groups since their launch two years ago. With the addition of the G versions, all 32-bit RX MCU family products for motor-control applications now support operating temperature from −40°C to +105°C, extending the scalability of the RX Family and providing system manufacturers a rich and scalable lineup to choose from.

The RX24T G Version and RX24U G Version are available now in mass production. The RX24T covers 11 models with pin counts ranging from 64 to 100 pins and memory sizes from 128 KB to 512 KB. The RX24U covers six models with pin counts ranging from 100 to 144 pins and memory sizes from 256 KB to 512 KB.

Renesas Electronics | www.renesas.com

Who killed the Quark?

By Eric Brown

Intel is phasing out its lightweight Quark processors, with final orders wrapping up this summer, and shipments ending in 2022. The Quark suffered from growing competition from high-end MCUs and low-end Cortex-A7 chips and the lack of a clear market focus.

When we read in AnandTech recently that Intel was discontinuing its Quark CPUs, the news was so unsurprising we almost decided to skip it. But perhaps it’s worthwhile to reflect on why this highly promoted crossover processor, which aimed to find a niche between low-end Cortex-A SoCs and high-end microcontroller units (MCUs), failed to catch fire.

According to AnandTech, Intel is phasing out all its Linux-ready Quark X10x SoCs and Quark SE and D1000/D2000 MCUs. Customers can post their final orders on July 19, and shipments on those orders will continue until July 17, 2022.


 
Former Intel CEO Krzanich with Quark chip in 2013 (left) and Curie module
(click images to enlarge)
The fate of the Quark seemed to be sealed in June 2017, when Intel announced it was discontinuing its Intel Joule and Intel Edison COMs and its open-spec Galileo Gen 2 SBC. The Galileo and Galileo II boards ran Linux on a Quark X1000 while the Edison, which was originally announced as a Quark-driven module, eventually shipped with an oddball “Tangier” Atom SoC. The Quark was used only as a co-processor.

Intel then launched the MCU-like Quark D1000, Quark D2000, and Quark SE models designed to run RTOSes like Zephyr instead of Linux. Intel backed the chips with a major marketing push for its tiny Curie wearable module, which uses a Quark SE. The Curie never took off, however, and in July 2017, Intel discontinued the Curie.

In the middle of this decade we saw a number of IoT gateways that ran Yocto Project stacks on the Quark X1000, but the combination appeared on relatively few third-party embedded boards. The last Quark-based embedded computer we saw was Advantech’s UBC-222, which launched a year ago.


Galileo II

When Intel announced the death of the Curie, it also discontinued its Curie-based Arduino 101 SBC. Arduino compatibility was always one of the key draws of the Quark, and several Edison breakout boards supported Arduino shields.

Yet, the Arduino community never embraced the Curie, and as the Linux-driven Raspberry Pi increasingly dominated the low-end hacker-board world, Arduino compatibility became less of a must-have feature. It certainly didn’t mean much to the luxury smartwatch vendors Intel was trying to woo with its Curie.


Arduino 101

The x86 community did not think much of the Quark, either. Its progress was slowed initially by the fact that the Quark was originally announced only with Pentium ISA compatibility. By the time Intel added x86 compatibility it was too late.

The Quark had more serious challenges, however. The smartwatch market was slow to take off, and the low-end wearables market that the Curie targeted was powered primarily by increasing powerful Arm Cortex-M MCUs. The growing support for wireless technology on these chips carved out a big chunk of the Quark’s market.



Aaeon’s Quark-based AIOT-QA, -QG, and -QM IoT gateways from 2016
(click image to enlarge)

(click image to enlarge)
Meanwhile, Arm’s Cortex-A7 design increasingly dominated the low-end Linux IoT market. The budget IoT gateways and other power-sipping IoT gear that used Quarks or MIPS chips in 2014 and 2015 had by 2017 largely switched to Cortex-A7 SoCs like NXP’s i.MX7 i.MX6 UL or the Allwinner A20, just to name a few.

Many of the SBCs in our recent catalog of 122 hacker boards that launched in the previous six months were Cortex-A7 designs. These include the MediaTek MT7623N based Banana Pi BPI-R2, the Rockchip PX2-SE driven Firefly-PX3-SE, the Allwinner V5 V100 powered Lindenis V5, the Allwinner H2+ or H3 based NanoPi Duo and Duo2, and the Rockchip RK3229 based ReSpeaker Core v2.0.


NanoPi Duo2

The Quark X1000 also felt pressure from Intel’s own Atom family of SoCs, which these days are more often tagged with the Celeron and Pentium brands. Atom SoCs have gradually improved power efficiency while also boosting performance, especially in graphics.

This was especially true of quad-core models. In the circa-2013 Bay Trail generation, the quad-core E3845 clocked in at 10W. Fast forward to the latest Gemini Lake generation, and the quad-core Pentium Silver N5000 has a 6.5W TDP. The drop in TDP was not significant enough for many embedded hackers, who continued to migrate to Arm, but it was enough to position some Atom chips closer to the Cortex-A7.

Perhaps Intel’s largest impediment was itself. It could never quite decide what the Quark was for and was never able to capture the developer market. The Curie was especially notorious for spotty public documentation and the requirement for signing NDAs to get the full specs.

The low-end chip market is tough going and marked by low margins. Intel had the market clout to succeed, but it was earning such high profits from its popular Xeon and Core chips, the Quark was quickly neglected. To a lesser degree, its Atom line has suffered from the same dynamics.

With IoT morphing into edge computing, and with the dropping costs for Cortex-A53 SoCs, the embedded market is shifting upward. Edge gateways are increasingly asked to process video and do analytics, which need more powerful chips. Still, there’s room at the bottom for more innovation on power-efficient SoCs that can still run Linux.

This article originally appeared on LinuxGizmos.com on January 30.

Intel | www.intel.com

8-Bit MCU Marries Ultra Low Power and Rich Analog I/O

STMicroelectronics has announced STM8L050, a low power 8-bit MCU that embeds rich analog peripherals, a DMA controller and separated data EEPROM—all in an inexpensive SO-8 package with up to six user I/Os. Built around ST’s STM8 core running at up to 16 MHz, the STM8L050 is well suited for resource-constrained products like industrial sensors, toys, access cards, e-bike controllers, home-automation or lighting products, smart printer cartridges or battery chargers.

The integrated DMA (Direct Memory Access) controller speeds application performance by streamlining data transfers between peripherals and memory, or from memory to memory, ultimately saving power consumption. The 256 bytes of separated EEPROM allows applications to store important program data when the MCU is powered down, while allowing maximum utilization of flash for code storage.

Alongside two comparators, the STM8L050 has a 4-channel 12-bit analog-digital converter (ADC) and a low-power real-time clock (RTC) with programmable alarm and periodic wakeups, allowing designers to minimize external analog components. In addition, support for either an external or internal clock at up to 16 MHz further enhances flexibility to balance performance with bill-of-materials (BOM) savings.

Other features include 8 KB of on-chip flash memory, 1 KB of RAM, two 16-bit timers, one 8-bit timer, and popular connectivity and debug interfaces including SPI, I2C, UART and SWIM. The STM8L050 provides power-saving modes that cut current to as little as 350 nA, and operates over a wide voltage range from 3.6 V down to 1.8 V. The MCUs are fully specified from -40°C to 125°C, ensuring robustness and reliability in demanding applications such as industrial controls or lighting products.

The STM8L050J3 is in production now, and available in the SO-8 package, priced from $0.25 for orders of 10,000 pieces.

STMicroelectronics | www.st.com