IoT-Leveraged Living Spaces
From preventive maintenance for appliances to voice-controlled lighting, the subsystems that comprise a modern Smart Home continue to evolve. Providing the building blocks for these implementations, IC vendors are keeping pace with specialized MCUs, sensors platforms and embedded software to meet diverse requirements.
The evolution of Smart Homes is about more than pure convenience. Smart Home technologies are leveraging IoT concepts to improve energy efficiency and security, thanks to intelligent, connected devices. The topic encompasses things like power-saving motor control systems, predictive maintenance, cloud-based voice assistance, remote monitoring and more.
Clearly the market is an attractive one. According to the latest Smart Home Device Database from market research firm IHS Markit, the global Smart Home market is forecast to grow by nearly a factor of five to reach more than $192 billion in 2023, up from $41 billion in 2018 (Figure 1). The report says that the fastest-growing device types in the market include lighting, smart speakers and connected major home appliances.
While it’s impossible to cover all the bases of Smart Home technology in a single article, here we’ll examine the microcontrollers (MCUs), analog ICs and special function chips that MCU vendors are developing to address Smart Home system designs.
An important piece of Smart Home technology is the idea of outfitting major home appliances with sophisticated maintenance features. With that in mind, in January Renesas Electronics launched its Failure Detection e-AI Solution for motor-equipped home appliances, featuring the Renesas RX66T 32-bit MCU. This solution with embedded AI (e-AI) enables failure detection of home appliances—such as refrigerators, air conditioners and washing machines—due to motor abnormality (Figure 2).
Property data showing the motor’s current or rotation rate status can be used directly for abnormality detection, making it possible to implement both motor control and e-AI–based abnormality detection with a single MCU. Using the RX66T eliminates the need for additional sensors, thereby reducing a customer’s bill of materials (BOM) cost.
When a home appliance malfunctions, the motor operation typically appears abnormal when running and being monitored for fault detection in real-time. By implementing e-AI-based motor control-based detection, the failure detection results can be applied not only to trigger alarms when a fault occurs, but also for preventive maintenance. For example, e-AI can estimate when repairs and maintenance should be performed, and it can identify the fault locations. This capability provides home appliance manufacturers the means to boost maintenance operations efficiency and improve product safety by adding functionality that predicts faults before they occur in their products.
The solution uses the Renesas Motor Control Evaluation System and an RX66T CPU card. This hardware is combined with a set of sample program files that run on the RX66T MCU as well as a GUI tool that enables collecting and analyzing property data indicating motor states. In order to detect faults, it is necessary to learn the characteristics of the normal state. Using the GUI tool, system engineers can immediately begin developing AI learning and optimized fault detection functionality. Once the AI models are developed, the e-AI development environment (composed of an e-AI Translator, e-AI Checker and e-AI Importer) can be easily used to import the learned AI models into the RX66T.
MCU FOR HOME AUTOMATION
The kind of MCU technologies required for the Smart Home must be extremally small sized, and have low power levels suited to low battery life. Addressing such needs, in February Microchip Technology launched what it claims is the industry’s smallest IEEE 802.15.4-compliant module that combines an ultra-low-power MCU with a sub-GHz radio. At half the size of the next smallest module on the market, the SAM R30 module is designed to meet the needs of space-conscious gear such as home automation sensors and controls (Figure 3).
Based on IEEE 802.15.4, the SAM R30 module supports proprietary networks that can be easily customized and configured. This is ideal for applications where interoperability is not desired due to their inherent vulnerability to remote attacks, such as alarm systems, building automation, smart cities and industrial sensor networks.
A key advantage of an IEEE 802.15.4-based network is that member devices can sleep for extended periods of time and remain part of the network. The SAM R30 module features ultra-low-power sleep modes, with wake from general-purpose I/O (GPIO) or its built-in real-time clock (RTC) while consuming approximately 800 nA. Devices can sleep for years, only waking as needed to transmit data.
Compact sensor designs can significantly reduce installation components and simplify device deployment. Applications often rely on simple double-sided tape for mounting, making decreasing the size of the sensor a priority. The SAM R30 module measures just 12.7 mm x 11 mm and includes the necessary features to drive any remote connected sensor, thereby eliminating the need for a separate MCU in the design. The device also offers up to 256 KB of flash and 40 KB of RAM, as well as serial data interfaces, USB and digital and analog I/O for advanced sensor development.
Operating in the sub-GHz RF spectrum, the SAM R30 module delivers two times the connectivity range and better propagation through walls and floors than similarly powered devices using the 2.4 GHz frequency band. This robustness is critical in applications such as leak detection, where the sensor may be buried deep in a remote cabinet, or for pool and spa controllers, which require reliable sub-GHz solutions that can communicate through exterior walls.
ALEXA FOR SIMPLE DEVICES
Voice control platforms are another key ingredient that define the concept of today’s Smart Home. As voice recognition platforms such as Apple’s Siri, Amazon’s Alexa and Google’s Google Assistant become more ubiquitous, Smart Home system developers have been eager to integrate those technologies into their implementations.
Facilitating such needs, last year STMicroelectronics rolled out its X-CUBE-AVS software package that enables Amazon’s Alexa Voice Service (AVS) to run on STM32 MCUs, allowing simple connected objects such as smart appliances, home-automation devices and office products to support advanced conversational user interfaces with cloud-based intelligence like automatic speech recognition and natural-language understanding (Figure 4).
As an expansion package for the STM32Cube software platform, X-CUBE-AVS contains ready-to-use libraries and open routines that accelerate porting the AVS SDK to the MCU. With application samples also included, it abstracts developers from the complex software layers needed to host AVS on an embedded device. AVS development usually targets more power-hungry and expensive microprocessors. In contrast, X-CUBE-AVS makes Alexa technology accessible to a wider spectrum of developers and projects.
The software handles low-layer communication and connection to AVS servers, provides application-specific services, and encapsulates the AVS protocol to ease application implementation. Connection management includes a persistent-token mechanism for directly restoring connection losses without repeated user authentication.
WAKE WORD SUPPORT
lso offering an Alexa-capable MCU solution, in February NXP Semiconductors unveiled an MCU-based voice control solution qualified with Amazon’s AVS. Built on an NXP i.MX RT crossover platform, this MCU-based AVS solution enables low latency, far-field, “wake word” detection, embeds all necessary digital signal processing capabilities, runs on Amazon FreeRTOS and includes an Alexa client application (Figure 5).
This MCU-based AVS solution provides OEMs with a self-contained, turnkey offering that enables them to quickly add Alexa to their products. It includes the MCU, the TFA9894D smart audio amplifier, optional A71CH secure element and comes with fully integrated software. It also features noise suppression, echo cancellation, beam forming and barge-in capabilities that enable use in acoustically difficult environments.
NXP offers at its Mougins, Sophia-Antipolis facilities a product testing service for Alexa built-in products, available to its customers who want to test their devices before submitting to Amazon for final evaluation. If a system developer’s product supports music and/or is far-field enabled and uses a “wake word” to initiate interactions with Alexa, additional testing is required prior to submitting products to Amazon for evaluation. This is where Pro-Support Audio Voice Services helps to complete the self-test checklists.
AUDIO AMPLIFIER SOLUTION
Audio amplifiers are another key technology for the voice control segment of Smart Home development. Along such lines, Texas Instruments (TI) offers digital-input Class-D audio amplifiers that enable engineers to deliver high-resolution audio in more Smart Home and voice-enabled applications. By combining high integration, real-time protection and new modulation schemes, TI’s audio devices allow designers to reduce board space and overall BOM costs. These new amplifiers are designed for personal electronics applications with any power level, like smart speakers, soundbars, TVs, notebooks, projectors and IoT applications.
An example from this family of amplifiers is the TAS2770 15 W audio amplifier. TI claims it as the first wide-supply I/V sense amplifier. The TAS2770 (Figure 6) offers state-of-the art, real-time speaker protection when paired with TI Smart Amp algorithms. The amplifier monitors loudspeaker behavior and increases loudness while improving audio quality in applications requiring small speakers.
The TAS2770 is an audio front end (AFE) that combines a digital microphone input with a powerful I/V sense amplifier. The device captures voice and ambient acoustic information for echo cancellation or noise reduction in voice-enabled applications. The TAS2770 monitors battery voltage and automatically decreases gain when audio signals exceed a set threshold, helping designers avoid clipping and extend playback time through end-of-charge battery conditions without degrading sound quality. Embedded systems designers can use TI’s PurePath Console software to easily configure the TAS2770. Engineers can jump-start their design with the TAS2770 Stereo Audio Subsystem Reference Design. Additional resources and reference designs are available to help engineers with their smart speaker designs.
SENSORS FOR SAFETY
For its part, Infineon Technologies provides a variety of technologies aimed at the Smart Home. For example, its range of XENSIV sensors enable highly accurate and reliable status monitoring in Smart Home devices. Meanwhile, its OPTIGA product family of hardware-based security solutions are designed to provide the right level of security to protect both data and devices in Smart Home appliances, says Infineon. And finally, the company also provides IGBT power semiconductors in discrete or module packages, driver ICs, highly-integrated IPM solutions and XMC MCUs—all well suited for Smart Home systems.
An example of the Infineon’s recent XENSIV offerings is its XENSIV PAS210, announced in June. According to the company, city dwellers often spend a large amount of their time indoors—either in an office, at school or simply at home. Urbanized spaces, however, tend to trap and develop bad air quality as they get more insulated for energy efficiency purposes. The concentration of CO2 is an indicator for bad air quality.
Many of today´s market solutions for monitoring this odorless and colorless gas are bulky and costly or simply not good enough for a widespread adoption. To address this issue, Infineon developed a disruptive CO2 sensor technology based on the photoacoustic spectroscopy (PAS). The XENSIV PAS210 sensor makes use of this new technology. It implements a high sensitivity MEMS microphone as a detector and enables significant miniaturization of CO2 sensors (Figure 7). For that reason, it is ideal for Smart Home applications and building automation—for demand-controlled ventilation, as well as various indoor air quality IoT devices such as air purifiers, thermostats, weather stations and personal assistants.
On a single PCB, the CO2 sensor integrates the photoacoustic transducer including the detector, the infrared source and the optical filter. It also holds an MCU for signal processing and algorithms as well as a MOSFET to drive an infrared source. XENSIV PAS210 uses the high SNR (signal-to-noise ratio) MEMS microphone XENSIV IM69D130 as a detector.
The device’s integrated MCU converts the MEMS microphone output into a ppm reading, which is available either via the serial I2C, UART or PWM interface. XENSIV PAS210 CO2 measurement capabilities cover a range from 0 ppm to 10,000 ppm with an accuracy of ±30 ppm or ±3% of the reading. In a pulsed mode, the XENSIV PAS210 CO2 sensor is designed to have a lifetime of ten years.
KIT WITH iCLOUD ACCESS
Among the Smart Home offerings from Cypress Semiconductor is its Wireless Internet Connectivity for Embedded Devices (WICED) Studio platform, a turnkey development platform for the IoT that simplifies the integration of wireless connectivity into smart home applications (Figure 8). Last year the company updated WICED adding iCloud remote access support for Wi-Fi-based accessories that support Apple HomeKit. Developers can leverage iCloud support in the WICED software Cypress WICED IoT Development Kit (SDK) and Cypress’ CYW43907 Wi-Fi MCU to create hub-independent platforms that connect directly to Siri voice control and the Apple Home app remotely.
Using Cypress’ WICED development platform and low power CYW20719 Bluetooth/BLE MCU, developers can integrate HomeKit support into products such as smart lighting devices, leverage Siri voice control and seamlessly connect to the Apple Home app. WICED Studio provides a single development environment for multiple wireless technologies, including Cypress’ Wi-Fi, Bluetooth and combo solutions, with an easy-to-use application programming interface in an integrated and interoperable wireless SDK.
The Cypress CYW43907 SoC integrates dual-band IEEE 802.11b/g/n Wi-Fi with a 320 MHz Arm Cortex-R4 RISC processor and 2 MB of SRAM to run applications and manage IoT protocols. The SoC’s power management unit simplifies power topologies and optimizing energy consumption. The WICED SDK provides code examples, tools and development support for the CYW43907.
UWB IN THE SMART HOME
Smart Home implementations rely on several wireless technologies—including Wi Fi, Bluetooth and others. But Ultra-Wideband (UWB) technology offers some unique advantages when it comes to applications where precise ranging and location determination is required. To help grow the UWB ecosystems, in August, the ASSA ABLOY Group (which includes HID Global), NXP Semiconductors, Samsung Electronics and Bosch announced the launch of the FiRa Consortium.
The new coalition is designed to grow the UWB ecosystem so new use cases for fine ranging capabilities can thrive, ultimately setting a new standard in seamless user experiences. Sony Imaging Products & Solutions, LitePoint and the Telecommunications Technology Association (TTA) are the first companies to join the newly-formed organization.
The FiRa name, which stands for “Fine Ranging,” highlights UWB technology’s unique ability to deliver unprecedented accuracy when measuring the distance or determining the relative position of a target. Especially in challenging environments, UWB technology outperforms other technologies in terms of accuracy, power consumption, robustness in RF connection and security, by a wide margin. The starting point for UWB technology is the IEEE standard 802.15.4/4z, which defines the essential characteristics for low-data-rate wireless connectivity and enhanced ranging.
While UWB is applicable to a variety of applications, there are some specific benefits for the Smart Home. The first is seamless access control. With today’s secure access technologies typically you have to perform an action—such as entering a code on a keypad or placing a finger on a scanner—in order to open a doorway and enter a secured area, like your home or garage. With a UWB setup, you simply approach the door and it opens, leave the door on the unsecure (outside) and it locks. The UWB-based solution tracks your approach, verifies your security credentials and lets you pass without having to stop and tap first.
Working securely in combination with other connectivity technologies, such as Bluetooth Low Energy (BLE) and Near Field Communication (NFC), UWB-driven access works in mobile phones, badges and other wearables, and can even lock or unlock doors when the device is turned off or in sleep mode (Figure 9).
UWB also provides Angle of Arrival (AoA) technology whereby two UWB devices can share relative ranging and positioning data to localize each other. In Smart Homes, networked devices and appliances can respond to your presence automatically, as you enter a room. As soon as you enter a room (or even approach the entry), the lights can turn on, the thermostat can be set to your favorite temperature and your preferred playlist can start streaming on the audio system. The technology is less intrusive, requires less oversight and supports your everyday routine, while enabling a more energy-efficient and sustainable lifestyle.
Certainly, the evolution of Smart Home technology is in its early stages in terms of market acceptance. But the building blocks in terms of control, wireless connectivity and sensing solutions already exist from a variety of vendors. This trend will continue as chip vendors craft new tools and solutions aimed at building robust Smart Home implementations.
Cypress Semiconductor | www.cypress.com
FiRa Consortium | www.firaconsortium.org
Infineon Technologies | www.infineon.com
Microchip Technology | www.microchip.com
NXP Semiconductor | www.nxp.com
Renesas Electronics | www.renesas.com
TMicroelectronics | www.st.com
Texas Instruments | www.ti.com
PUBLISHED IN CIRCUIT CELLAR MAGAZINE • OCTOBER 2019 #351 – Get a PDF of the issueSponsor this Article