Making Sense of Industrial Connectivity
Wireless connectivity is making its presence felt in the industrial market. In many types of buildings, cables and traditional monitoring equipment are being replaced with sensor nodes in intelligent networks to reduce energy consumption, while adding convenience and security.
The Internet of Things (IoT) is having an impact beyond the consumer market, manifesting itself in the industrial areas of building and factory automation. The IoT integrates a broad set of sensors – temperature, pressure, humidity, ambient lighting – which can be connected within a building to gather and send data about temperature, lighting, occupancy and humidity levels to create a comfortable, efficient environment. In addition, sensors are used to help monitor and control the production line on a factory floor to enable a smarter, more efficient manufacturing process. The sensor nodes communicate wirelessly to gateways and from there to the cloud. The nature of the environment means sensors have to be robust to withstand harsh environments.
The demands of embedded sensing systems require that they be compact, as they are often integrated into existing shared spaces; they have to be stable, with reliable links that can process data in real-time; but, more importantly, they have to be energy efficient.
“The innovation of wireless sensor nodes in building and factory automation is at an inflection point in terms of adoption and capabilities,” observes Ajinder Singh, General Manager, Building Automation, Lighting and Display, Texas Instruments. “We see a lot of desire to add intelligence to existing building infrastructures or the assembly line without worrying about wiring or installation in hard-to-reach areas.” However, it is adding intelligence that is critical.
“A hot topic is how to have it all connected smartly to the management of the building,” he says. “There is a proliferation of processing power, sensing technology and advances in low-power management, but stumbling blocks are when we look at IoT or smart connectivity, using the cloud. A compelling application needs low-power analog, smart power management and a radio protocol so that we can address the key challenge of long battery life of sensing nodes.”
In HVAC systems, rather than having one central temperature-monitoring device, adding multiple battery-operated wireless sensor nodes throughout a building provides more options to control heating and cooling zones based on occupancy or time of day. Also, large commercial buildings can use interrupts from wireless Passive Infra Red (PIR)-sensing nodes to trigger people-counting systems for demand control ventilation and add fresh air based on the amount of people occupying a room, rather than having the HVAC system turn on based on a preset control.
Many of the connected sensing designs currently in development rely on small CR2032 Li-Ion coin-cell batteries to extend battery life for 10 to15 years as compared to two to three years in today’s systems. In essence this “lick it and stick it” approach to wireless sensor nodes means that consumers do not need to worry about installation costs, intrusive wiring or replacing batteries in the sensors in a short space of time – they can simply ‘stick’ sensors wherever needed.
Data is processed and transferred to other nodes on the network to implement a change in conditions. This requires compelling and differentiated solutions that offer the processing and power management capabilities to which Singh refers.
As an example, Texas Instruments’ SimpleLink™ portfolio of wireless microcontrollers (MCUs) for Wi-Fi®, Bluetooth® low energy, Sub-1 GHz, ZigBee®, 6LoWPAN and ZigBee RF4CE™ technologies integrate a low-power radio, as well as an ARM® Cortex®-M3 or M4 processor into a single device. The devices in the SimpleLink ultra-low power platform were designed for low power operation, but with significant performance capabilities to perform additional applications such as calibration or data pre-processing on top of the connectivity tasks. This platform provides the flexibility to develop products that support multiple wireless connectivity standards for building and factory automation applications using a single-chip. All 2.4 GHz devices (for example, ZigBee and Bluetooth) as well as Sub-1 GHz solutions are pin-to-pin compatible. Additionally, one device in the family supports all 2.4 GHz technologies in the same device, which allows building and factory automation developers to choose which radio they want to use later in the development cycle.
The newest member of the portfolio is the SimpleLink dual-band CC1350 wireless MCU, which is a great example of how semiconductor vendors are embracing integration in processors. The wireless MCU is capable of handling both Sub-1 GHz and 2.4 GHz Bluetooth low energy connectivity; it is part of the new generation of highly integrated devices, with analog-to-digital converters (ADC) and functionalities such as power management. As well as a very low power RF transceiver, it has a general-purpose 48 MHz ARM Cortex-M3 core which can run additional user-programmed applications. There is a dedicated radio controller, an embedded ARM Cortex-M0 processor, to manage the low-level RF protocol commands in the ROM or RAM for low-power operation.
Nodes on the network have to operate for long periods of time on a single battery, as their location may mean that it is difficult, expensive, or both, to replace a battery frequently. It is not uncommon for a device to be expected to operate in the field for 10 years on a coin cell battery.
An ultra-low power sensor controller integrated into some of the SimpleLink devices provides the processing levels to sample data and make simple sensor decisions. For example, it can regularly poll a sensor output in any part of the building to determine if a threshold event has occurred, allowing the application processor to go into sleep mode while the sensor controller manages the network.
The device’s duty cycle is likely to dictate how often it needs to be in a wake state. For example, a smart water meter may need to be awake just once a day to communicate with the utility company, says Avner Goren, General Manager, Embedded Processing Strategic Marketing, TI. To detect leaks, however, it may need to be awake more often, perhaps checking in once every few seconds. How often the sensor needs to communicate creates the parameters, as well as how often the device needs to connect to the cloud, which in turn dictates the power modes that need to be applied.
Alternatively, the sensors can harvest energy from around the buildings or factories themselves. Singh cites the example of beacons which TI has designed using Bluetooth low energy technology. Used in lit areas, they harvest energy from indoor light over 200lux. This is sufficient to allow the beacon to keep sending a message every second, which can be tracked via a smartphone app. This allows companies to keep track of assets or products, or in retail environments, stores can track if you need a particular special offer displayed on your smartphone. With energy harvesting, there is no need to replace batteries in the thousands of beacons in buildings today, says Singh.
“One of the biggest challenges in these types of automation systems is to interface with the analog circuitry without waking up the MCU,” explains Goren. “The Analog Front End (AFE) has to work while the digital controller is in sleep mode. The solution is to separate power inside the device, deciding which portion is kept awake while the MCU is in sleep mode, depending on the application,” he explains.
To protect assets like keys, data, code or identity, security features are required such as secure boot, encryption acceleration and debug protection to prevent anyone entering via a debugger to hack the device. Security scope can be selected and implemented by the OEM according to the specific system being built, which assets need protection and where the exposure points are – for example runtime execution or where data is stored.
“Working with the cloud requires end-to-end security,” says Goren. Data packets sent over Wi-Fi are protected because encryption is within the Wi-Fi protocol. Cloud services are more varied, he continues, as the cloud provider demands a specific security protocol and specific messaging protocols when the client-cloud link is established. However, each provider, such as Amazon Web Services (AWS) or Microsoft Azure IoT platform, has its own security and messaging protocols. This requires another layer of security on top of Wi-Fi security, whereby the cloud provider verifies if the device connecting to the cloud is authorised for access. Most security is implemented on the MCU or TI’s SimpleLink solution that connects to the network. This makes the route to market quicker.
The conversation with customers is an important one. Ajinder Singh’s group takes products from across TI – analog, sensing, power management and processors – and puts together a reference design for the customer. “In the IoT space, it is important to get prototyping quickly and efficiently,” he says.
The problem in industrial applications, says Singh, is that one size does not fit all. “Bluetooth low energy does some things well, while mesh protocols are most useful in some applications . . . our job is to provide subsystem solutions, which allow customers to differentiate the product offering.” To do this, the company provides an application example with a reference design as a starting point. There are over 100,000 analog and embedded processor products in TI’s portfolio, so selecting the right device combination can be daunting. Singh believes it is important to have plenty of reference design options. “We want designers to quickly create innovation in next-generation connected sensor designs and push the limit of the imagination of what can be done.”
Reference designs definitely help reduce development time for design engineers who want to create innovative building and factory automation projects. TI has several key designs they can choose, such as an indoor light energy harvesting reference design for Bluetooth low energy (BLE) beacon subsystems and humidity and temp sensor nodes for star networks enabling 10+ tear coin cell battery life. “Reference designs allow a broader set of customers to handle wireless sensor development,” says Goren. “There are many new players that come up with a service, or a system idea, but don’t have the technical know-how.” Given the number of protocols in place in building automation in particular, he says, the idea that concepts and then prototypes can be developed easily will encourage innovation. TI Design reference designs offer online selection and support in the form of design files (schematics, bill of materials, Gerber files, and layout files), firmware, and application software. In addition, TI’s engineer-to-engineer (E2E) community allows developers of all experience levels to ask or respond to questions via the web, and large customers can access local field application engineers who can help at the customer’s site.
Goren offers the example of how a pressure sensor for in-vehicle use can be created using a SimpleLink SensorTag kit that features 10 low-power (Micro Electo Mechanical Systems) MEMS sensors and is preloaded with software to connect to the cloud in minutes. The SensorTag kit can transmit any sensing data quickly to the cloud, for example if anything is on or touches the seat of a car. If, as the project evolves, designers decide that an LED and a siren need to be incorporated as visual and audible alarms, then a LaunchPad™ development kit can be used for debugging and function changes, or to add test and connector points to the system. The company’s low-cost MCU LaunchPad development kits offer an easy start, he says, with a broad ecosystem of plug-in modules and scalable software available to connect to the cloud. To add a display or other functionality, there are several BoosterPack plug-in modules which can be easily added on top of the LaunchPad kit.
Beyond hardware and software, TI is committed to helping its customers understand what needs to be addressed and solved, and to select the right products. For example, says Goren, there are explanations of applications and the ability to drill down to block diagrams, and to product pages, to see specific devices that solve a particular issue. This data can also be used to select the right analog circuitry and sensors, and see how these can be connected to the wireless network. Each reference design represents a specific function in end equipment, for example a battery charger in a detector.
The support available from TI allows a broader set of customers to design products for factory or building automation applications, or the IoT, asserts Goren. “We have to assume there will be many new players that develop service or system ideas that don’t have the technical know-how that traditional OEMs have,” he said.