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SmartCTherm IoT Sensor Node: a Smart Sensor IoT Node by EBV Elektronik

In the world of IoT, there are many different paths a designer can take to achieve the same goal. When starting from scratch, the designer is faced with a vast number of choices: which sensors are best suited for the given task? Which connectivity solution to choose? Which MCU platform provides the best performances and is supported by the most comprehensive development environment? Finally, how to fit all this into a given energy consumption budget? Seemingly trivial, these questions are not easy to answer, especially considering the rapid emergence of new products in the semiconductor market. The wrong answer may easily lead to a failure to deliver on time and lose on the aggressive IoT market.

Building on the extensive experience in the semiconductors distribution business, EBV’s Smart Sensing & Connectivity (SSC) experts have the technical expertise and market knowledge to answer all these questions with confidence. Their latest project, the SmartCTherm IoT sensor node, is based on the latest IoT-ready solutions from Renesas and Sequans. The SmartCTherm project is not only a smart IoT sensor node with cellular LPWA connectivity in an NB-IoT/Cat M form-factor, but also a full suite of services such as technical support, on-demand workshop and demonstration, training, and partnership. It is a full-fledged IoT solution, aimed at the broadest range of IoT designers and developers.

Designing the perfect IoT solution: plans and decisions

During the planning phase, the team set three main goals: 

  • Everywhere – connect seamlessly and let your data be seen everywhere
  • Bring value – sensors bring more than just a value – they bring data
  • Visualize – eye candy GUI provides the best user experience

The first prerequisite was seamless connectivity from any location, everywhere. The team also wanted to have the ability to process raw sensor data and convert it into some practically useful information. In other words, they wanted high processing performance with as little power consumption as possible. Finally, an appealing user interface can make the whole difference for many users. Humans, as mostly visual beings, process visual data representation much more efficiently. For this reason, appealing GUIs become more and more in demand.

After setting their goals, the SSC designers were able to move on to the next stage: carefully selecting the components and deciding on a development platform that would be in line with their plans. After much thought, they decided on a two-fold solution: 

  • EBV-IoT Sequans GM01Q Connectivity Shield
  • EK-RA6M3G evaluation and development kit from Renesas

In this article, I will try to explain the reasoning behind some of the choices and decisions EBV’s SSC designers have made.

EBV-IoT Sequans GM01Q Connectivity Shield: a deep dive

The EBV-IoT Sequans GM01Q Connectivity Shield (EBV-IoT shield) is based on the Monarch GM01Q LTE module from Sequans Communications. In addition to the LTE module, the shield also incorporates two environmental sensors from Renesas: the HS3001 digital relative humidity (RH) & temperature sensor, and the ZMOD4410 Metal Oxide (MOX)-based gas sensor for indoor air quality (TVOC) detection. There are some additional supporting components for various purposes (SIM 2FF cardholder, protocol converters, level translators, ESD protection, LDOs, etc.), but these won’t be separately discussed in this article.

Since security is an important aspect of any IoT design, the EBV-IoT shield also includes the ATECC608A secure element (SE) from Microchip. The ATECC608A SE provides a hardware root of trust, enabling the implementation of various security features, such as the TLS protocol. To read more about the ATECC608A SE and all the benefits it provides over some alternative solutions, please visit the following BLOG ARTICLE.

 EBV-IoT Sequans GM01Q Connectivity Shield

The EBV-IoT shield offers a broad range of wired connectivity options, including a Micro USB port, PMOD extension connector, and SEEED connector with additional I2C lines (to name a few). Standard Arduino UNO (stackable) headers provide easy connectivity to a wide range of development and evaluation kits based on this widely accepted standard. 

Wireless connectivity

Connectivity is undoubtedly one of the most important aspects of a typical IoT design. The first item in the EBV designers’ three-point plan was a broad and seamless connection. Everywhere. This narrowed down the choice to LTE-based modules that can operate worldwide, using the well-established cellular network infrastructure, while consuming minimal amounts of power. Also, it was necessary to keep the associated costs (e.g., subscription) to a minimum. After considering many different connectivity solutions, EBV’s SSC experts opted for the Monarch GM01Q LTE module form Sequans Communications. To better understand their choice, we will briefly discuss some of the most common LPWA solutions and the module itself.

LPWA on cellular technologies

Low-Power Wide-Area (LPWA) networks represent a new class of wireless technology, specifically designed to meet the needs of IoT applications. Typical IoT applications operate with low data transfer rates and exchange only small amounts of data once an hour or even once a day (e.g., IoT sensor nodes used in agriculture). Conversely, those applications require wide area coverage with very low power consumption (yet again, IoT sensor nodes in agriculture are perfect examples). Although there are some specialized proprietary technologies (LoRa and Sigfox, to name a few), it would be preferable to have an open and globally standardized solution. In this regard, the 3GPP consortium released three new technologies focused on LPWA and machine to machine (M2M) communication, but we will discuss only two of them: NB-IoT (LTE-CAT NB1, CAT0), and LTE CAT M1 (LTE-M or eMTC).

The NB-IoT and LTE CAT M1 are two leading cellular LPWA technologies. Both offer lower power consumption, excellent coverage, and better scalability (up to 150 k devices per base station) while reducing the operating costs at the same time, compared to more commonly used cellular technologies (3G, 4G…). The LTE CAT M1 technology leans towards higher data-rates (up to 350 kbps) and provides better support for mobile applications, while the NB IoT is focused on very low data rates (down to 20 kbps), and it is ideal for static sensor applications (such as the SmartCTherm IoT sensor node). Most importantly, these technologies do not require separate cellular infrastructure; they can be deployed by simply upgrading the software on the existing cellular infrastructure in most cases, significantly reducing deployment and maintenance costs.

Monarch GM01Q: a closer look

Monarch GM01Q is an all-in-one, single-mode LTE-M and NB-IoT module with worldwide deployment and roaming capability, based on the Sequans’ highly-acclaimed Monarch LTE platform. It includes all the supporting elements needed to form an ultra-compact LTE modem solution, housed in a tiny 20 x 21 x 15 mm LGA package (pin-compatible with the entire Q series). It adds seamless IoT connectivity, while consuming exceptionally low power for the features it offers. It runs Sequans’ carrier-proven LTE protocol stack and features a rich set of AT commands. It can be accessed over its primary high-speed UART interface and it also supports data transfer over Point to Point Protocol (PPP). If you need more technical details about the Monarch GM01Q module, please visit our New Products Introduction (NPI) page.

Renesas

With respect to what was stated earlier, the choice of the controller platform was not an easy one. After all, this largely predetermines the development path, making it either simple and straightforward or perplexing and time-consuming. As a brand-new addition to EBV’s line card of suppliers, Renesas offers some exciting solutions. Our designers were eager to try them out. Intrigued by their RA6 family of advanced MCUs, EBV designers decided to go with Renesas; more precisely, with the EK-RA6M3G development and evaluation kit, based on the RA6M3 variant of their RA6 MCUs family.

 SmartCTherm IoT node: EK-RA6M3G with the EBV-IoT shield installed

The EK-RA6M3G evaluation kit also features an Arduino UNO pinout-compatible extension (among many other connectivity options), allowing seamless integration with the EBV-IoT shield. On top of that, each pin of the MCU is accessible via standard 2.54 mm (1 inch) double-row connectors, allowing peripherals such as the TFT screen with the capacitive touch panel to be integrated very easily.

Software development ecosystem

The RA6M3 MCU is a mid-high tier of Renesas MCUs optimized for IoT applications. It features a large amount of memory, high performances, a rich set of peripherals, and more. However, its main advantage is enabling a very advanced, yet easy to use development ecosystem from Renesas.

The Renesas RA family of MCUs is supported by the Flexible Software Package (FSP) that provides a suite of production-ready peripheral libraries, drivers, and software stacks (Ethernet, USB, file system) as well as AWS FreeRTOS®, allowing to take the full advantage of the RA Partner Ecosystem. The RA Partner Ecosystem incorporates more than 50 different suppliers, delivering ready-made software and hardware building blocks that work seamlessly across the entire RA MCU family. This powerful suite of tools provides a comprehensive integrated framework for the rapid development of complex embedded applications.

There are multiple development environment (IDE) options to choose from: Renesas popular Synergy e2 Studio offers the native support for the RA family, offering many useful features, such as the intelligent pin mapping or the smart configurator. However, the developers are also free to use other popular IDEs, including KEIL MDK or IAR Embedded Workbench, which both support Renesas RA family of MCUs. 

AppWizard is a Graphical User Interface (GUI) creation tool from SEGGER. Together, Renesas’ FSP and SEGGER’s graphical libraries (emWin) provide a seamless GUI development experience. AppWizard is a graphical point-and-click environment that allows creating GUI elements and actions very quickly and intuitively. All the parameters can be fully customized, including screen resolution, color depth, and various other parameters. The preview function is also available, allowing designers to test GUI before uploading the code to the actual hardware. The AppWizard fits seamlessly into the powerful Renesas Synergy e2 studio Integrated Solution Development Environment (ISDE), complementing it with a versatile GUI creation tool.

SmartCTherm Software Architecture

The software architecture on the SmartCTherm IoT is quite straightforward. There are several threads running in parallel under AWS FreeRTOS®, providing quick and responsive user experience. The diagram below clearly illustrates the generic software architecture, which is very easy to build using ready-made solutions provided by Renesas and its partners: 

Simplified block-diagram of the software architecture

The RA6M3 MCU communicates with the sensors and the touch panel via the standard I2C interface (Sensors and Touch threads). Communication with the Monarch GM01Q is performed via the UART interface, using AT commands. Historically, AT command set has been used as a standard way to communicate with modems ever since Hayes introduced them back in 1981 for their Smartmodem series. Therefore, the AT command set is also known as the Hayes command set.

Each command starts with the AT string, which stands for “Attention,” followed by the command string itself. One of the main tasks of the MCU is to perform AT commands parsing, which usually means sending formatted AT commands and taking appropriate actions after the response is received from the modem (AT commands thread). The remaining two threads are self-explanatory: date/time information is updated within the Blinky thread, while the SEGGER’s emWin GUI libraries run within their own thread (emWIN thread).

Cloud Connectivity

The sole purpose of the Monarch GM01Q module is to establish a link with the Cloud. The SmartCTherm relies on using MQTT messaging protocol designed for lightweight M2M communications, which runs on top of the TCP layer. The MQTT is a publish/subscribe-based protocol and can use TLS for enhanced security. The MQTT (and the MQTTS, its more secure variant) are widely accepted protocols by many Cloud service providers. Currently the SmartCTherm IoT node is preconfigured to connect to the Cayenne Cloud service. However, with minor tweaking of the connection parameters, it can connect to virtually any MQTT-enabled cloud, including very advanced Cloud platforms such as MS Azure, AWS, or – Avnet IoTConnect.

Avnet IoTConnect is a full-fledged platform as a Service (PaaS). This horizontal IoT platform allows for device communication and management, data storage, app creation as well as enablement and robust security protocols. Find out more about the Avnet IoTConnect platform on this LINK.

Conclusion

Today, IoT developers are faced with increasingly high demands from the rapidly growing IoT market. They must rely on various rapid development solutions, hoping to reach very tight deadlines. A reliable and comprehensive rapid development ecosystem can differentiate between failure and success in this highly competitive market segment. Our SSC experts had the chance to test Renesas’ development ecosystem while developing the SmartCTherm smart IoT node, and they were delighted with the outcome. If you want to learn more about Renesas and its rapid development solutions, be sure not to miss demonstrations, webinars, workshops, and other promotional activities offered by our EBV SSC team.

To learn more about this solution, first hand, from our experts – Register for the webinar here: LINK

AUTHORS:

Uros MALI, Director segment Smart Sensing & Connectivity, EBV Elektronik
Darko ILIJEVSKI, Technical Editor, EBV Elektronik

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