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.)

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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

Tailored Solutions Tackle Design Needs for Wearables

Low Power Priorities

For wearable devices, every drop of power is precious. That’s driving designers of these embedded systems to attack the power challenge from multiple angles. Fortunately, a slew of analog, power and system ICs have emerged that address the wearable market’s particular needs.

By Jeff Child, Editor-in-Chief

While power is an important issue in any embedded system design, it’s especially critical in wearable devices. Today’s generation of wearable electronics require longer battery lives, more functionality and better performance—all in extremely small form factors. Wearables comprise a wide variety of products including smartwatches, physical activity monitors, heart rate monitors, smart headphones and more.
Today’s wearable electronic devices share some common design priorities. First, they have an extremely low budget for power consumption. And because they’re not suited to being powered by replaceable batteries, they usually require a way for the unit to be recharged. Meanwhile, most modern wearables require some kind of wireless connectivity.

Feeding those needs, chip vendors—primarily from the microcontroller (MCU) and analog sectors—over the past 12 months have announced a generous mix of solutions to help keep power consumption low, to aid recharging and to enable new capabilities while maintaining narrow power constraints. Chip and platform solutions aimed at wearables span the range from specialized power management ICs (PMICs), data converters and power regulator chips, to wireless charging solutions and even complete reference design platforms specially for wearables.

Wrist-Worn Health Gear

Wearables have evolved from being more than just fun devices for health and fitness. Using sophisticated sensors and other capabilities, devices are being designed to do virtual care monitoring, assess chronic conditions and evaluate overall well-being. Along just those lines, in September Maxim Integrated announced its Health Sensor Platform 2.0 (HSP 2.0) (Figure 1). This wrist-worn platform can be used for rapid prototyping, evaluation and development. It provides the ability to monitor electrocardiogram (ECG), heart rate and body temperature from a wrist-worn wearable, saving up to six months in development time, according to Maxim.

Figure 1
The Health Sensor Platform 2.0 is a wrist-worn platform that can be used for rapid prototyping, evaluation and development. It provides the ability to monitor electrocardiogram (ECG), heart rate and body temperature from a wrist-worn wearable.

In the past, system developers have found it challenging to derive precise ECG monitoring from the wrist—most alternatives require a wearable chest strap. Getting accurate body temperature typically requires using a thermometer at another location. Maxim has overcome these challenges in the HSP 2.0. by using its proprietary sensor and health monitoring technology.

Enclosed in a watch casing, the wrist-based form factor enables HSP 2.0 to provide basic functionality out of the box, with body-monitoring measurements starting immediately. Data can be stored on the platform for patient evaluation or streamed to a PC for analysis later. Unlike other wearables, the data measurements collected by the HSP 2.0 can be owned by the wearer. This alleviates data privacy concerns and enables users to conduct their own data analysis. Also, because HSP 2.0 is an open platform, designers can evaluate their own algorithms on the board. In addition, the modular format is future proof to quickly accommodate new sensors over time.

HSP 2.0 includes the following Maxim chips: the MAX32630 DARWIN low-power MCU for wearables; the MAX32664 ultra-low-power biometric sensor hub with embedded heart-rate algorithm; the MAX20303 PMIC; the MAX30205 human body temperature sensor with ±0.1°C accuracy; the MAX30001 single-channel integrated biopotential and bioimpedance analog front-end (AFE) solution; and the MAX86141 optical pulse oximeter and heart-rate sensor.

Energy Controller for Wearables

For its part, Renesas Electronics has been working on meeting extreme low power demands by applying innovations in semiconductor process development. In November the company unveiled an innovative energy-harvesting embedded controller that can eliminate the need to use or replace batteries in a device. Developed based on Renesas’ SOTB (silicon-on-thin-buried-oxide) process technology, the new embedded controller achieves extreme reduction in both active and standby current consumption. The extreme low current levels of the SOTB-based embedded controller enables system designers to completely eliminate the need for batteries in some of their products through harvesting ambient energy sources such as light, vibration and flow (Figure 2).

Figure 2
The extreme low current levels of the SOTB-based embedded controller enables system designers to completely eliminate the need for batteries in some of their products through harvesting ambient energy sources such as light, vibration and flow.

Although the solution was developed with IoT devices in mind, the controller is more broadly aimed at what they call the new market of maintenance-free, connected IoT sensing devices with endpoint intelligence. This includes health and fitness apparel, shoes, wearables, smart watches and drones. Renesas’ first commercial product using SOTB technology, the R7F0E embedded controller, is a 32-bit, Arm Cortex-based embedded controller. The device is capable of operating up to 64 MHz for rapid local processing of sensor data and execution of complex analysis and control functions.

The R7F0E consumes just 20 μA/MHz active current, and only 150 nA deep standby current, approximately one-tenth that of conventional low-power MCUs. According to the company, samples of the new R7F0E embedded controller are available now for beta customers, and samples are scheduled to be available for general customers from July 2019. Mass production is scheduled to start from October 2019.

LDO Regulator for Wearables

Achieving longer battery lives is a problem that can be attacked from many angles. Power regulator electronics are among those. With that in mind, Microchip Technology in October introduced a linear Low Dropout (LDO) regulator that extends battery life in portable devices up to four times longer than traditional ultra-low quiescent (IQ) LDOs. With an ultra-low IQ of 250 nA versus the approximately 1 µA operation of traditional devices, the MCP1811 LDO reduces quiescent current to save battery life, enabling end users to recharge or replace batteries less often (Figure 3).

Figure 3
With an ultra-low IQ of 250 nA versus the approximately 1 µA operation of traditional devices, the MCP1811 LDO regulator saves battery life, enabling end users to recharge or replace batteries less often.

Well suited for IoT and battery-operated applications such as wearables, remotes and hearing aids, the LDO reduces power consumption in applications by minimizing standby or shutdown current. Reducing standby power consumption is critical in remote, battery-powered sensor nodes, where battery replacement is difficult and operating life requirements are high. Available in package options as small as 1 mm x 1 mm, the MCP1811 consumes minimal board space to meet the needs of today’s compact portable electronic designs. Depending on the application and number of LDOs, designers can take advantage of the extra board space with a larger battery to further increase battery life.

An additional benefit the MCP1811 offers is faster load line and transient response when compared to other ultra-low IQ LDOs. Faster response times can accelerate wake-up speed in devices such as monitors or sensors that require immediate attention. Faster transient response can help designers avoid undervoltage and overvoltage lockout measures used in sensitive applications where transient spikes can lead to catastrophic results.

Secure Payments with Wearables

An important capability in a certain class of wearables is the ability to support electronic retail transactions directly from the wearable device. While this is arguably a whole separate technology category in itself, we’ll touch on a couple developments here. In November, Infineon Technologies announced an EMV-based payment solution for key chains, rings, wristbands, bracelets and other wearable devices.

The SECORA Pay W for Smart Payment Accessories (SPA) combines an EMV chip with the card operating system, payment applet as well as the antenna directly on the unit. As a turnkey solution it allows card vendors, device manufacturers, financial institutions or event organizers to quickly and cost-efficiently introduce fashion accessories for payment and even access.

Infineon’s SECORA Pay solutions portfolio comprises the SECORA Pay S for standard Visa and MasterCard payment cards, SECORA Pay X for applications with extended features such as multi-application, national debit and white label schemes or access management and SECORA Pay W for payment accessories. All SECORA turn-key solutions are pre-certified by Mastercard and Visa and will accelerate the deployment of contactless payment. The EMV Chip Specifications (www.emvco.com) define globally valid requirements for chip-based payment solutions and acceptance terminals. They enable secure contact- and contactless applications and the use of other emerging payment technologies.

Complete Payment SoC

Likewise a player in the contactless transaction market, STMicroelectronics (ST) back in October announced teaming up with Fidesmo to create a turnkey active solution for secure contactless payments on smart watches and other wearable technology. The complete payment system-on-chip (SoC) is based on ST’s STPay-Boost IC, which combines a hardware secure element to protect transactions and a contactless controller featuring proprietary active-boost technology that maintains reliable NFC connections even in devices made with metallic materials. Its single-chip footprint fits easily within wearable form factors (Figure 4).

Figure 4
The STPay-Boost IC combines a hardware secure element to protect transactions and a contactless controller featuring proprietary active-boost technology that maintains reliable NFC connections even in devices made with metallic materials. Its single-chip footprint fits easily within wearable form factors.

ST’s proprietary NFC-boosting active load modulation technology simplifies RF design and accelerates time to market by ensuring superior performance with little or no circuit optimization needed. A small-size antenna can sustain robust and reliable wireless connection, permitting smaller overall product dimensions and lower power consumption resulting in longer battery life.

Fidesmo’s MasterCard MDES tokenization platform completes the solution by allowing the user to load the personal data needed for payment transactions. Convenient Over-The-Air (OTA) technology makes personalization a simple step for the user without any special equipment. Kronaby, a Sweden-based hybrid smartwatch maker, has embedded the STPay-Boost chip in its portfolio of men’s and women’s smart watches that offer differentiated features such as freedom from charging and filtered notifications. The SoC with Fidesmo tokenization enables Kronaby watches to support a variety of services such as payments, access control, transportation and loyalty rewards.

Data Converters

Data converters also have role to play in efforts to meet the extreme low power needs of wearable devices. Along such lines, in December Texas Instruments (TI) introduced four tiny precision data converters (Figure 5). The new data converters enable designers to add more intelligence and functionality, while shrinking system board space. The DAC80508 and DAC70508 are eight-channel precision digital-to-analog converters (DACs) that provide true 16- and 14-bit resolution, respectively.

Figure 5
The DAC80508 and DAC70508 are eight-channel precision DACs that provide true 16- and 14-bit resolution, respectively. The ADS122C04 and ADS122U04 are 24-bit precision ADCs that feature a two-wire, I2C-compatible interface and a two-wire, UART-compatible interface, respectively.

The ADS122C04 and ADS122U04 are 24-bit precision analog-to-digital converters (ADCs) that feature a two-wire, I2C-compatible interface and a two-wire, UART-compatible interface, respectively. The devices are optimized for a variety of small-size, high-performance or cost-sensitive electronics applications such as wearables.

Both DACs include a 2.5-V, 5-ppm/°C internal reference, eliminating the need for an external precision reference. Available in a 2.4-mm-by-2.4-mm die-size ball-grid array (DSBGA) package or wafer chip-scale package (WCSP) and a 3-mm-by-3-mm quad flat no-lead (QFN)-16 package, these devices are up to 36% smaller than the competition, says TI. Meanwhile, the tiny, 24-bit precision ADCs are available in 3-mm-by-3-mm very thin QFN (WQFN)-16 and 5-mm-by-4.4-mm thin-shrink small-outline package (TSSOP)-16 options. The two-wire interface requires fewer digital isolation channels than a standard serial peripheral interface (SPI), reducing the overall cost of an isolated system. These precision ADCs eliminate the need for external circuitry by integrating a flexible input multiplexer, a low-noise programmable gain amplifier and other circuitry.

Memory Innovations

Among the latest innovations aimed at wearables from Cypress Semiconductor is an FRAM (ferroelectric random access memory)-based data logging solution. In November, Cypress introduced a nonvolatile data-logging solution with ultra-low power consumption. This solution is well suited for portable medical and wearable devices that demand nonvolatile memories to continuously log an increasing amount of user and sensor data while using as little power as possible.

Cypress’ Excelon LP FRAM is an energy-efficient device that provides instant-write capabilities with virtually unlimited endurance (Figure 6). This enables wearable systems to perform mission-critical data logging requirements while maximizing battery life. The Excelon LP series is available in a low-pin-count, small-footprint package that is suited for space-constrained, wearable applications.

Figure 6
The Excelon LP FRAM provides instant-write capabilities with virtually unlimited endurance. This enables wearable systems to perform mission-critical data logging requirements while maximizing battery life.

The Excelon LP series offers 4-Mb and 8-Mb industrial and commercial-grade densities with 50 MHz and 20 MHz Serial Peripheral Interface (SPI) performance. The series reduces power consumption with 100 nA hibernate and 1 µA standby modes that greatly improve a battery-powered product’s user experience by extending system operating time. The device’s inherent instant writes also eliminate power failure “data-at-risk” due to volatile data buffers in legacy memories. The family features wide voltage operation from 1.71 V to 3.6 V and is available in RoHS-compliant industry-standard packages that are pin compatible with EEPROMs and other nonvolatile memories. Excelon LP F-RAMs provide 1,000-trillion (1015) read/write cycle endurance with 10 years of data retention at 85°C or 151 years at 65°C.

Charging Wearables

A common aspect of wearable devices is that they tend not to be suited for replaceable batteries. As a result, they typically need to be recharged. Wireless (cordless) battery charging is beginning to take hold as a solution. Feeding such needs, in October Analog Devices announced its Power by Linear LTC4126 as an expansion of its offerings in wireless battery charging. The LTC4126 combines a wireless powered battery charger for Li-Ion cells with a high efficiency multi-mode charge pump DC-DC converter, providing a regulated 1.2 V output at up to 60 mA (Figure 7).

Figure 7
The LTC4126 combines a wireless powered battery charger for Li-Ion cells with a high efficiency multi-mode charge pump DC-DC converter, providing a regulated 1.2 V output at up to 60 mA.

Charging with the LTC4126 allows for a completely sealed end product without wires or connectors and eliminates the need to constantly replace non-rechargeable (primary) batteries. The efficient 1.2 V charge pump output features pushbutton on/off control and can directly power the end product’s ASIC. This greatly simplifies the system solution and reduces the number of necessary external components. The device is ideal for space-constrained low power Li-Ion cell powered wearables such as hearing aids, medical smart patches, wireless headsets and IoT devices.

The LTC4126, with its input power management circuitry, rectifies AC power from a wireless power receiver coil and generates a 2.7 V to 5.5 V input rail to power a full-featured constant-current/constant-voltage battery charger. Features of the battery charger include a pin selectable charge voltage of 4.2 V or 4.35 V, 7.5 mA charge current, automatic recharge, battery temperature monitoring via an NTC pin, and an onboard 6-hour safety charge termination timer. Low battery protection disconnects the battery from all loads when the battery voltage is below 3.0 V. The LTC4126’s charge pump switching frequency is set to 50 kHz/75 kHz to keep switching noise out of the audible range, ideal for audio related applications such as hearing aids and wireless headsets. The IC is housed in a compact, low profile (0.74 mm) 12-lead 2 mm × 2 mm LQFN package. The device is guaranteed for operation from –20°C to 85°C in E-grade.

Kit for Wireless Charging

Also facilitating building wireless chargers for wearables, ST for its part offers a kit-level solution. The ST plug-and-play wireless battery-charger development kit (STEVAL-ISB045V1) lets users quickly build ultra-compact chargers up to 2.5 W with a space-saving 20 mm-diameter coil, for charging small IoT devices and wearables such as smart watches, sports gear or healthcare equipment (Figure 8).

Figure 8
The ST plug-and-play wireless battery-charger development kit lets users quickly build ultra-compact chargers up to 2.5 W with a space-saving 20 mm-diameter coil, for charging small IoT devices and wearables such as smart watches, sports gear or healthcare equipment.

Built around the STWBC-WA wireless charging-transmitter controller, the kit comprises a charging base unit containing a transmitter board with the 20 mm coil already connected and ready to use. Getting started is easy, using the PC-based STSW-STWBCGUI software to configure the STWBC-WA and monitor runtime information such as power delivered, bridge frequency, demodulation quality and protocol status. The kit includes a dongle for running the GUI. The supporting ecosystem includes certified reference boards, software and detailed documentation to help developers quickly design chargers for wearables.

The STWBC-WA controller chip contains integrated drivers and natively supports full-bridge or half-bridge topologies for powering the antenna. The half-bridge option allows charging up to 1 W with a smaller-diameter coil for an even more compact form factor. The chip supports all standard wireless-charging features, including Foreign Object Detection (FOD) and active presence detection for safe charging, and uses digital feedback to adapt the transmitted power for optimum efficiency at all load conditions. Two firmware options give users the choice of a fast turnkey solution or customizing the application using APIs to access on-chip peripherals including an ADC, a UART and GPIOs.

Clearly there are many facets and angles to address the low power needs of wearables. As demands for more functionality rise, system developers will need to remain ever mindful of keeping battery life at the same lengths or longer. Fortunately, there seems to be no stopping the innovation among chip vendors targeting this growing wearables market.

RESOURCES

Analog Devices | www.analog.com
Cypress Semiconductor | www.cypress.com
Infineon Technologies | www.infineon.com
Maxim Integrated | www.maximintegrated.com
Microchip Technology | www.microchip.com
Renesas Electronics America | www.renesas.com
STMicroelectronics | www.st.com
Texas Instruments | www.ti.com

This article appeared in the March 344 issue of Circuit Cellar

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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 | www.espressif.com

 

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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March Circuit Cellar: Sneak Preview

The March issue of Circuit Cellar magazine is out next week!. We’ve rounded up an outstanding selection of in-depth embedded electronics articles just for you, and rustled them all into our 84-page magazine.

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POWER MAKES IT POSSIBLE

Power Issues for Wearables
Wearable devices put extreme demands on the embedded electronics that make them work—and power is front and center among those demands. Devices spanning across the consumer, fitness and medical markets all need an advanced power source and power management technologies to perform as expected. Circuit Cellar Chief Editor Jeff Child examines how today’s microcontroller and power electronics are enabling today’s wearable products.

Power Supplies for Medical Systems
Over the past year, there’s been an increasing trend toward new products that have some sort of application or industry focus. That means supplies that include either certifications, special performance specs or tailored packaging intended for a specific application area such as medical. This Product Focus section updates readers on these technology trends and provides a product gallery of representative medical-focused power supplies.

DESIGN RESOURCES, ISSUES AND CHALLENGES

Flex PCB Design Services
While not exactly a brand-new technology, flexible printed circuit boards are a critical part of many of today’s challenging embedded system applications from wearable devices to mobile healthcare electronics. Circuit Cellar’s Editor-in-Chief, Jeff Child, explores the Flex PCB design capabilities available today and whose providing them.

Design Flow Ensures Automotive Safety
Fault analysis has been around for years, and many methods have been created to optimize evaluation of hundreds of concurrent faults in specialized simulators. However, there are many challenges in running a fault campaign. Mentor’s Doug Smith presents an improved formal verification flow that reduces the number of faults while simultaneously providing much higher quality of results.

Cooling Electronic Systems
Any good embedded system engineer knows that heat is the enemy of reliability. As new systems cram more functionality at higher speeds into ever smaller packages, it’s no wonder an increasing amount of engineering mindshare is focusing on cooling electronic systems. In this article, George Novacek reviews some of the essential math and science around cooling and looks are several cooling technologies—from cold pates to heat pipes.

MICROCONTROLLER PROJECTS WITH ALL THE DETAILS

MCU-Based Solution Links USB to Legacy PC I/O
In PCs, serial interfaces have now been just about completely replaced by USB. But many of those interfaces are still used in control and monitoring embedded systems. In this project article, Hossam Abdelbaki describes his ATSTAMP design. ATSTAMP is an MCS-51 (8051) compatible microcontroller chip that can be connected to the USB port of any PC via any USB-to-serial bridge currently available in the market.

Pet Collar Uses GPS and Wi-Fi
The PIC32 has proven effective for a myriad of applications, so why not a dog collar? Learn how Cornell graduates Vidya Ramesh and Vaidehi Garg built a GPS-enabled pet collar prototype. The article discusses the hardware peripherals used in the project, the setup, and the software. It also describes the motivation behind the project, and possibilities to expand the project in the future.

Guitar Video Game Uses PIC32
While music-playing video games are fun, their user interfaces tend leave a lot to be desired. Learn how Cornell students Jake Podell and Jonah Wexler designed and built a musical video game that’s interfaced with using a custom-built wireless guitar controller. The game is run on a Microchip PIC32 MCU and uses a TFT LCD display to show notes that move across the screen towards a strum region.

… AND MORE FROM OUR EXPERT COLUMNISTS

Non-Evasive Current Sensor
Gone are the days when you could do most of your own maintenance on your car’s engine. Today they’re sophisticated electronic systems. But there are some things you can do with the right tools. In his article, By Jeff Bachiochi talks about how using the timing light on his car engine introduced him to non-contact sensor technology. He talks about the types of probes available and how to use them to read the magnitude of alternating current (AC

Impedance Spectroscopy using the AD5933
Impedance spectroscopy is the measurement of a device’s impedance (or resistance) over a range of frequencies. Brian Millier has designed many voltammographs and conductivity meters over the years. But he recently came across the Analog Devices AD5933 chip made by which performs most all the functions needed to do impedance spectroscopy. In this article, explores the technology, circuit design and software that serve these efforts.

Side-Channel Power Analysis
Side-channel power analysis is a method of breaking security on embedded systems, and something Colin O’Flynn has covered extensively in his column. This time Colin shows how you can prove some of the fundamental assumptions that underpin side-channel power analysis. He uses the open-source ChipWhisperer project with Jupyter notebooks for easy interactive evaluation.

Firms Team Up to Provide End-to-End LoRa Security Solution

Microchip Technology, in partnership with The Things Industries, has announced the what it claims is industry’s first end-to-end security solution that adds secure, trusted and managed authentication to LoRaWAN devices at a global scale. The solution brings hardware-based security to the LoRa ecosystem, combining the MCU- and radio-agnostic ATECC608A-MAHTN-T CryptoAuthentication device with The Things Industries’ managed join servers and Microchip’s secure provisioning service.

The joint solution significantly simplifies provisioning LoRaWAN devices and addresses the inherent logistical challenges that come with managing LoRaWAN authentication keys from inception and throughout the life of a device. Traditionally, network and application server keys are unprotected in the edge node, and unmonitored, as LoRaWAN devices pass through various supply chain steps and are installed in the field.

The Common Criteria Joint Interpretation Library (JIL) “high”-rated ATECC608A comes pre-configured with secure key storage, keeping a device’s LoRaWAN secret keys isolated from the system so that sensitive keys are never exposed throughout the supply chain nor when the device is deployed. Microchip’s secure manufacturing facilities safely provision keys, eliminating the risk of exposure during manufacturing. Combined with The Things Industries’ agnostic secure join server service to the LoRaWAN network and application server providers, the solution decreases the risk of device identity corruption by establishing a trusted authentication when a device connects to a network.

Similar to how a prepaid data plan works for a mobile device, each purchase of an ATECC608A-MAHTN-T device comes with one year of managed LoRaWAN join server service through The Things Industries. Once a device identifies itself to join a LoRaWAN network, the network contacts The Things Industries join server to verify that the identity comes from a trusted device and not a fraudulent one. The temporary session keys are then sent securely to the network server and application server of choice. The Things Industries’ join server supports any LoRaWAN network, from commercially operated networks to private networks built on open-source components. After the one-year period, The Things Industries provides the option to extend the service.

Microchip and The Things Industries have also partnered to make the onboarding process of LoRaWAN devices seamless and secure. LoRaWAN device identities are claimed by The Things Industries’ join server with minimal intervention, relieving developers from needing expertise in security. Customers can not only choose any LoRaWAN network but can also migrate to any other LoRaWAN join server by rekeying the device. This means there is not a vendor lock-in and customers have full control over where and how the device keys are stored.

The ATECC608A is agnostic and can be paired with any MCU and LoRa radio. Developers can deploy secure LoRaWAN devices by combining the ATECC608A with the SAM L21 MCU, supported by the Arm Mbed OS LoRaWAN stack, or the recently-announced SAM R34 System-in-Package with Microchip’s LoRaWAN stack. For rapid prototyping, designers can use the CryptoAuthoXPRO socket board and The Things Industries provisioned parts in samples with the SAM L21 Xplained Pro (atsamd21-xpro) or SAM R34 Xplained Pro (DM320111).

The ATECC608A-MAHTN-T device for The Things Industries, including the initial year of prepaid TTN service, is available in volume production for $0.81 each in 10,000-unit quantities.

Microchip Technology | www.microchip.com

 

MCUs Serve Up Solutions for Car Infotainment

Dashboard Dazzle

As automotive dashboard displays get more sophisticated, information and entertainment are merging into so-called infotainment systems. The new systems are driving a need for powerful MCU solutions that support the connectivity, computing and interfacing requirements particular to these designs.

(Caption for lead image Figure 1: The Cypress Wi-Fi and Bluetooth combo solution uses Real Simultaneous Dual Band (RSDB) technology so that Apple CarPlay (shown) and Android Auto can operate concurrently without degradation caused by switching back and forth between bands.).

By Jeff Child, Editor-in-Chief

Microcontroller (MCU) vendors have a rich legacy of providing key technologies for nearly every aspect of an automobile’s electronics—everything from the powertrain to the braking system to dashboard displays. In recent years, they’ve taken on a new set of challenges as demands rise for ever more sophisticated “infotainment” systems. Advanced touchscreen, processing, networking, voice recognition and more are parts of these subsystems tasked with providing drivers with information and entertainment suited to today’s demands—demands that must rival or exceed what’s possible in a modern smartphone or tablet. And, as driverless cars inch toward mainstream reality, that hunger for rich infotainment functionality will only increase.

In order to meet those system design needs, MCU vendors are keeping pace with highly integrated chip-level solutions and embedded software tailored specifically to address various aspects of the automotive infotainment challenge. Over the past 12 months, MCU companies have announced products aimed at everything from advanced dashboard graphics to connectivity solutions to security technologies. At the same time, many have announced milestone design wins that illustrate their engagement with this dynamic sub-segment of automotive system development.

Smartphone Support

Exemplifying these trends, in July Cypress Semiconductor announced that Pioneer integrated Cypress’ Wi-Fi and Bluetooth Combo solution into its flagship in-dash navigation AV receiver. The solution enables passengers to display and use their smartphone’s apps on the receiver’s screen via Apple CarPlay (Figure 1–lead image above) or Android Auto, which provide the ability to use smartphone voice recognition to search for information or respond to text messages. The Cypress Wi-Fi and Bluetooth combo solution uses Real Simultaneous Dual Band (RSDB) technology so that Apple CarPlay and Android Auto can operate concurrently without degradation caused by switching back and forth between bands.

The Pioneer AVH-W8400NEX receiver uses Cypress’ CYW89359 combo solution, which includes an advanced coexistence engine that enables optimal performance for dual-band 2.4- and 5-GHz 802.11ac Wi-Fi and dual-mode Bluetooth/Bluetooth Low Energy (BLE) simultaneously for advanced multimedia experiences. The CYW89359’s RSDB architecture enables two unique data streams to run at full throughput simultaneously by integrating two complete Wi-Fi subsystems into a single chip. The CYW89359 is fully automotive qualified with AECQ-100 grade-3 validation and is being designed in by numerous top-tier car OEMs and automotive suppliers as a full in-vehicle connectivity solution, supporting infotainment and telematics applications such as smartphone screen-mirroring, content streaming and Bluetooth voice connectivity in car kits.

In October, Cypress announced another infotainment-related design win with Yazaki North America implementing Cypress’ instrument cluster solution to drive the advanced graphics in Yazaki’s instrument cluster for a leading American car manufacturer. According to Cypress, Yazaki selected the solution based on its unique offering of five chips that combine to drive dual displays and provide instant-on memory performance with automotive-grade, ASIL-B safety compliance. The Cypress solution is based on a Traveo MCU, along with two high-bandwidth HyperBus memories in a multi-chip package (MCP), an analog power management IC (PMIC) for safe electrical operation, and a PSoC MCU for system management support. The Traveo devices in the Yazaki instrument cluster were the industry’s first 3D-capable Arm Cortex-R5 cluster MCUs.

Virtualization Embraced

The complexity of automotive infotainment systems has pushed system developers to embrace advanced operating system approaches such as virtualization. Feeding those needs, last June Renesas Electronics rolled out its “R-Car virtualization support package” designed to enable easier development of hypervisors for the Renesas R-Car automotive system-on-chip (SoC). The R-Car virtualization support package includes, at no charge, both the R-Car hypervisor development guide document and sample software for use as reference in such development for software vendors who develop the embedded hypervisors that are required for integrated cockpits and connected car applications.

A hypervisor is a virtualization operating system (OS) that allows multiple guest OSs— such as Linux, Android and various real-time OSs (RTOS)—to run completely independently on a single chip. Renesas announced the R-Car hypervisor in April of 2017 and the new R-Car virtualization Support Package was developed to help software vendors accelerate their development of R-Car hypervisors.

The company’s third-generation R-Car SoCs were designed assuming that they would be used with a hypervisor. The Arm CPU cores, graphics cores, video/audio IP and other functions include virtualization functions. Originally, for software vendors to make use of these functions, they would have had to understand both the R-Car hardware manuals and the R-Car virtualization functions and start by looking into how to implement a hypervisor. Now, by following development guides in the R-Car virtualization support package, not only can software vendors easily take advantage of these functions, they will be able to take full advantage of the advanced features of R-Car. Also, by providing sample software that can be used as a reference, this package supports rapid development.

Technology partnerships have been playing a key role in automotive infotainment trends. Along just those lines, in September Renesas and OpenSynergy, a supplier of automotive hypervisors, announced that the Renesas’ SoC R-Car H3 and OpenSynergy’s COQOS Hypervisor SDK were adopted on Parrot Faurecia’s automotive safe multi-display cockpit. The latest version of Android is the guest OS of the COQOS Hypervisor, which executes both the instrument cluster functionality, including safety-relevant display elements based on Linux, and the Android-based in-vehicle infotainment (IVI) on a single R-Car H3 SoC chip (Figure 2). The COQOS Hypervisor SDK shares the R-Car H3 GPU with Android and Linux allowing applications to be presented on multiple displays, realizing a powerful and flexible cockpit system.

Figure 2
With Android as the guest OS of the COQOS Hypervisor, it executes both the instrument cluster functionality, including safety-relevant display elements based on Linux, and the Android-based in-vehicle infotainment (IVI) on a single R-Car H3 SoC chip.

According to OpenSynergy’s CEO Stefaan Sonck Thiebaut, the COQOS Hypervisor SDK takes full advantage of the hardware and software virtualization extensions provided by Renesas. The OpenSynergy solution includes key features, such as shared display, which allows several virtual machines to use multiple displays flexibly and safely. The R-Car H3 GPU and video/audio IP incorporates virtualization functions, making virtualization by the hypervisor possible and allowing for multiple OSs to operate independently and safely. OpenSynergy’s COQOS Hypervisor SDK is built around a safe and efficient hypervisor that can run software from multipurpose OSs such as Linux or Android, RTOS and AUTOSAR-compliant software simultaneously on one SoC.

Large Touchscreen Support

As the content provided by automotive infotainment systems gets more sophisticated, so too must the displays and user interface technologies that interact with that content. With that in mind, MCU vendors are offering more advanced touchscreen control solutions. Dashboard screens have unique design challenges. Screens in automobiles need to meet stringent head impact and vibration tests. That means thicker cover lenses that potentially impact the touch interface performance. Meanwhile, as screens get larger, they are also more likely to interfere with other frequencies such as AM radio and car access systems. All of these factors become a major challenge in the design of modern automotive capacitive touch systems.

Along just those lines, Microchip in December announced its maXTouch family of single-chip touchscreen controllers designed to address these issues for screens up to 20 inches in size (Figure 3). The MXT2912TD-A, with nearly 3,000 touch sensing nodes, and MXT2113TD-A, supporting more than 2,000 nodes, bring consumers the touchscreen user experience they expect in vehicles. These new devices build upon Microchip’s existing maXTouch touchscreen technology that is widely adopted by manufacturers worldwide. Microchip’s latest solutions offer superior signal-to-noise capability to address the requirements of thick lenses, even supporting multiple finger touches through thick gloves and in the presence of moisture.

Figure 3
The maXTouch family of single-chip touchscreen controllers is designed for screens up to 20 inches in size, and supports up to 3,000 touch sensing nodes. The devices even support multiple finger touches through thick gloves and in the presence of moisture.

As automakers use screens to replace mechanical switches on the dash for sleeker interior designs, safe and reliable operation becomes even more critical. The MXT2912TD and MXT2113TD devices incorporate self- and sensor-diagnostic functions, which constantly monitor the integrity of the touch system. These smart diagnostic features support the Automotive Safety Integrity Level (ASIL) classification index as defined by the ISO 26262 Functional Safety Specification for Passenger Vehicles.

The new devices feature technology that enables adaptive touch utilizing self-capacitance and mutual-capacitance measurements, so all touches are recognized and false touch detections are avoided. They also feature Microchip’s proprietary new signal shaping technology that significantly lowers emissions to help large touchscreens using maXTouch controllers meet CISPR-25 Level 5 requirements for electromagnetic interference (EMI) in automobiles. The new touch controllers also meet automotive temperature grade 3 (-40°C to +85°C) and grade 2 (-40°C to +105°C) operating ranges and are AEC-Q100 qualified.

3D Gesture Control

Aside from the touchscreen display side of automotive infotainment, Microchip for its part has also put its efforts toward innovations in 3D human interface technology. With that in mind, in July the company announced a new 3D gesture recognition controller that offers the lowest system cost in the automotive industry, providing a durable single-chip solution for advanced automotive HMI designs, according to Microchip. The MGC3140 joins the company’s family of easy-to-use 3D gesture controllers as the first qualified for automotive use (Figure 4).

Figure 4
The MGC3140 3D gesture controller is Microchip’s first qualified for automotive use. It’s suited for a range for applications such as navigating infotainment systems, sun shade operation, interior lighting and more.

Suited for a range for applications that limit driver distraction and add convenience to vehicles, Microchip’s new capacitive technology-based air gesture controller is ideal for navigating infotainment systems, sun shade operation, interior lighting and other applications. The technology also supports the opening of foot-activated rear liftgates and any other features a manufacturer wishes to incorporate with a simple gesture action.

The MGC3140 is Automotive Electronics Council AEC-Q100 qualified with an operating temperature range of -40°C to +125°C, and it meets the strict EMI and electromagnetic compatibility (EMC) requirements of automotive system designs. Each 3D gesture system consists of a sensor that can be constructed from any conductive material, as well as the Microchip gesture controller tuned for each individual application.

While existing solutions such as infrared and time-of-flight technologies can be costly and operate poorly in bright or direct sunlight, the MGC3140 offers reliable sensing in full sunlight and harsh environments. Other solutions on the market also come with physical constraints and require significant infrastructure and space to be integrated in a vehicle. The MGC3140 is compatible with ergonomic interior designs and enables HMI designers to innovate with fewer physical constraints, because the sensor can be any conductive material and hidden from view.

Vehicle Networking

While applicable to areas beyond infotainment, an automobile’s ability to network with the outside world has become ever more important. As critical vehicle powertrain, body, chassis, and infotainment features increasingly become defined by software, securely delivering updates such as fixes and option packs over the air (OTA) enhances cost efficiency and customer convenience. Serving those needs, in October STMicroelectronics released its latest Chorus automotive MCU that provides a gateway/domain-controller solution capable of handling major OTA updates securely.

With three high-performance processor cores, more than 1.2 MB RAM and powerful on-chip peripherals, ST’s new flagship SPC58 H Line joins the Chorus Series of automotive MCUs and can run multiple applications concurrently to allow more flexible and cost-effective vehicle-electronics architectures (Figure 5). Two independent Ethernet ports provide high-speed connectivity between multiple Chorus chips throughout the vehicle and enable responsive in-vehicle diagnostics. Also featuring 16 CAN-FD and 24 LINFlex interfaces, Chorus can act as a gateway for multiple ECUs (electronic control units) and support smart-gateway functionality via the two Ethernet interfaces on-chip.

Figure 5
The SPC58 H Line of MCUs can run multiple applications concurrently to allow more flexible and cost-effective vehicle-electronics architectures. Two independent Ethernet ports provide high-speed connectivity between multiple Chorus chips throughout the vehicle.

To protect connected-car functionalities and allow OTA updates to be applied safely, the new Chorus chip contains a Hardware Security Module (HSM) capable of asymmetric cryptography. Being EVITA Full compliant, it implements industry-leading attack prevention, detection and containment techniques.

Working with its large on-chip 10 MB flash, the SPC58NH92x’s context-swap mechanism allows current application code to run continuously even while an update is downloaded and made ready to be applied later at a safe time. The older software can be retained, giving the option to roll-back to the previous version in an emergency. Hyperbus and eMMC/SDIO high-speed interfaces to off-chip memory are also integrated, enabling further storage expansion if needed.

Single Cable Solution

Today’s automotive infotainment systems comprise mobile services, cross-domain communication and autonomous driving applications as part of in-vehicle networking. As a result, these systems require a more flexible solution for transporting packet, stream and control content. Existing implementations are either costly and cumbersome, or too limited in bandwidth and packet data capabilities to support system updates and internetworking requirements.

To address this need, Microchip Technology in November announced an automotive infotainment networking solution that supports all data types—including audio, video control and Ethernet—over a single cable. Intelligent Network Interface Controller networking (INICnet) technology is a synchronous, scalable solution that significantly simplifies building audio and infotainment systems, offering seamless implementation in vehicles that have Ethernet-oriented system architectures (Figure 6).

Figure 6
INICnet technology is a synchronous, scalable solution that significantly simplifies building audio and infotainment systems, offering seamless implementation in vehicles that have Ethernet-oriented system architectures.

Audio is a key infotainment feature in vehicles, and INICnet technology provides full flexibility through supporting a variety of digital audio formats with multiple sources and sinks. INICnet technology also provides high-speed packet-data communications with support for file transfers, OTA software updates and system diagnostics via standard Ethernet frames. In this way, INICnet technology supports seamless integration of Internet Protocol (IP)-based system management and data communications, along with very efficient transport of stream data. INICnet technology does not require the development and licensing of additional protocols or software stacks, reducing development costs, effort and time.

INICnet technology provides a standardized solution that works with both Unshielded Twisted Pair (UTP) at 50 Mbps and coaxial cable at 150 Mbps. With low and deterministic latency, INICnet technology supports deployment of complex audio and acoustics applications. Integrated network management supports networks ranging from two to 50 nodes, as well as processor-less or slim modules where the node is remotely configured and managed. The solution’s Power over Data Line (PoDL) capability saves costs on power management for microphones and other slim modules. Nodes can be arranged in any order with the same result, and any node in the system can directly communicate with any other node in the system.

Security for Connected Cars

As cars become more network-connected, the issue of security takes on new dimensions. In October, Infineon Technologies announced a key effort in cybersecurity for the connected car by introducing a Trusted Platform Module (TPM) specifically for automotive applications—the first on the market, according to the company. The new OPTIGA TPM 2.0 protects communication between the car manufacturer and the car, which increasingly turns into a computer on wheels. A number of car manufacturers already designed in Infineon’s OPTIGA TPM.

The TPM is a hardware-based security solution that has proven its worth in IT security. By using it, car manufacturers can incorporate sensitive security keys for assigning access rights, authentication and data encryption in the car in a protected way. The TPM can also be updated so that the level of security can be kept up to date throughout the vehicle’s service life.

Cars send real-time traffic information to the cloud or receive updates from the manufacturer “over the air,” for example to update software quickly and in a cost-effective manner. The senders and recipients of that data—whether car makers or individual components in the car—require cryptographic security keys to authenticate themselves. These critical keys are particularly protected against logical and physical attacks in the OPTIGA TPM as if they were in a safe.

Early Phase Critical

Incorporating the first or initial key into the vehicle is a particularly sensitive moment for car makers. When the TPM is used, this step can be carried out in Infineon’s certified production environment. After that, the keys are protected against unauthorized access; there is no need for further special security precautions. The TPM likewise generates, stores and administers further security keys for communication within the vehicle. And it is also used to detect faulty or manipulated software and components in the vehicle and initiate troubleshooting by the manufacturer in such a case.

Figure 7
The SLI 9670 consists of an attack-resistant security chip (shown) and high-performance firmware developed in accordance with the latest security standard. The firmware enables immediate use of security features, such as encryption, decryption, signing and verification.

The SLI 9670 consists of an attack-resistant security chip and high-performance firmware developed in accordance with the latest security standard (Figure 7). The firmware enables immediate use of security features, such as encryption, decryption, signing and verification. The TPM can be integrated quickly and easily in the system thanks to the open source software stack (TSS stack) for the host processor, which is also provided by Infineon. It has an SPI interface, an extended temperature range from -40°C to 105°C and the advanced encryption algorithms RSA-2048, ECC-256 and SHA-256. The new TPM complies with the internationally acknowledged Trusted Computing Group TPM 2.0 standard, is certified for security according to Common Criteria and is qualified in accordance with the automotive standard AEC-Q100.

Side by side with driverless vehicle innovations, there’s no doubt that infotainment systems represent one of the most dynamic subsets of today’s automotive systems design. MCU vendors offer a variety of chip and software solutions addressing all the different pieces of car infotainment requirements from display interfacing to connectivity to security. Circuit Cellar will continue to follow these developments. And later this year, we’ll take a look specifically at MCU solutions aimed at enabling driverless vehicles and assisted driving technologies.

RESOURCES

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

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February Circuit Cellar: Sneak Preview

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

MCUs ARE EVERYWHERE, DOING EVERYTHING

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

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

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

WE’VE GOT THE POWER

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

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

EMBEDDED COMPUTING FOR YOUR SYSTEM DESIGN

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

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

… AND MORE FROM OUR EXPERT COLUMNISTS

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

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

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

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

Tool Extension Enables Neural Networking on STM32 MCUs

STMicroelectronics has extended its STM32CubeMX ecosystem by adding advanced Artificial Intelligence (AI) features.  AI uses trained artificial neural networks to classify data signals from motion and vibration sensors, environmental sensors, microphones and image sensors, more quickly and efficiently than conventional handcrafted signal processing. With STM32Cube.AI, developers can now convert pre-trained neural networks into C-code that calls functions in optimized libraries that can run on STM32 MCUs.
STM32Cube.AI comes together with ready-to-use software function packs that include example code for human activity recognition and audio scene classification. These code examples are immediately usable with the ST SensorTile reference board and the ST BLE Sensor mobile app. Additional support such as engineering services is available for developers through qualified partners inside the ST Partner Program and the dedicated AI and Machine Learning (ML) STM32 online community. ST will demonstrate applications developed using STM32Cube.AI running on STM32 MCUs this week in a private suite at CES, the Consumer Electronics Show, in Las Vegas, January 8-12.

The STM32Cube.AI extension pack can be downloaded inside ST’s STM32CubeMX MCU configuration and software code-generation ecosystem. Today, the tool supports Caffe, Keras (with TensorFlow backend), Lasagne, ConvnetJS frameworks and IDEs including those from Keil, IAR and System Workbench.

The FP-AI-SENSING1 software function pack provides examples of code to support end-to-end motion (human-activity recognition) and audio (audio-scene classification) applications based on neural networks. This function pack leverages ST’s SensorTile reference board to capture and label the sensor data before the training process. The board can then run inferences of the optimized neural network. The ST BLE Sensor mobile app acts as the SensorTile’s remote control and display.

The comprehensive toolbox consisting of the STM32Cube.AI mapping tool, application software examples running on small-form-factor, battery-powered SensorTile hardware, together with the partner program and dedicated community support offers a fast and easy path to neural-network implementation on STM32 devices.

STMicroelectronics | www.st.com