The Internet-of-Things (IoT) is already having a significant impact on many aspects of our lives, as we work, play and go about our daily tasks. With tens of billions of connected devices and millions more being added every week, it’s hard to imagine the extent to which global networks will enhance the world we live in.
Apart from their functionality – primarily as a sensor, actuator, or a combination- and the strong preference to be wireless, these connected devices share two further common requirements. They need to be able to communicate with other devices with a host and with the cloud; they also need to have frugal power requirements due to commonly being powered by tiny coin-cell batteries so that they can be self-sufficient and as small as possible.
The IoT is a challenging area for designers as they strive to meet the increasingly tough demands and expectations of users and consumers. While designs are physically small, they are also complex systems incorporating many different technologies and designers must make use of sophisticated techniques and low power componentry to achieve their goals.
Bluetooth Low Energy
Bluetooth is extensively used within IoT applications as it is available on every smartphone and tablet, thereby offering almost ubiquitous access to the internet, and includes features that are well-aligned with the needs of IoT deployments. Originally termed ‘Bluetooth Smart,’ Bluetooth Low Energy transmits data in packets then enters a sleep mode, which saves significant power. Bluetooth 4 also allows connections/pairings to be maintained while dormant, a further means of saving energy.
Bluetooth continues to evolve and features such as secure pairing, AES-128 encryption and profiles that support rapid development are included in later versions. The 4.2 release improved packet capacity by 10x and data range by 2.5x opening up applications requiring greater data throughput.
Bluetooth 5 is the current version and is optimized for IoT applications. Bandwidth has doubled to 2 Mbps and, possibly the most significant advance in Bluetooth 5, is the inclusion of mesh capability that removes the need for a hub, allowing more expansive IoT networks to be created.
Enumerating IoT applications is a challenge as there are so many, with more being added at a rapid rate. The IoT connects the homes we live in, monitors our wellbeing, manages our workplaces, enhances the cities where we live and the vehicles we travel around in, and more.
The IoT transcends the consumer and industrial markets. In industry, nodes monitor processes to enhance product quality as well as keeping an eye on machinery to assess wear, enabling preventative maintenance that saves the costs associated with downtime. In logistics, Bluetooth Low Energy-based scanners can help track inventory via intelligent tags, while sensors flag the need to refill containers or replenish stock.
With an increasing reliance on battery power and global awareness of the need to reduce consumption, energy management is a significant issue everywhere. Bluetooth Low Energy-based IoT nodes in smart buildings sense the need for heat, light, cooling and ventilation and control lights, windows and HVAC equipment in real-time to operate in the most economical way, often turning resources off when an area is unoccupied.
In our homes, Bluetooth Low Energy can enable the tracking of white goods use, and even initiate re-ordering to auto-refill our refrigerators. To address the needs of an aging population, Bluetooth is enabling a new generation of personal health monitors to connect remotely located medical professionals to their patients to lessen the need for hospital visits while simultaneously improving the quality of health care.
Designing Bluetooth Low Energy-based IoT Solutions
IoT solutions can be complex to realize as they require a broad spectrum of technologies to work in harmony. These might include microcontrollers, analog design blocks for the sensors and RF design for communications and power management. All of this typically needs to be combined within a small form factor solution with minimal power demands.
As a result, designers are looking for integrated solutions that are specifically designed to support rapid, low-risk design processes for IoT applications. The RSL10 System-in-Package (RSL10 SiP) is an example of such a device that provides an all-in-one solution for adding Bluetooth Low Energy to IoT nodes.
The RSL10 SiP is a flexible, ultra-miniature Bluetooth 5 certified device that integrates the RSL10 Bluetooth Low Energy radio SoC, integrated antenna and all passive components in a complete small-form factor system. Fully certified to all worldwide standards (CE, FCC, IC, MIC, KC), the RSL10 SiP significantly improves time by removing the need for additional RF design expertise or certification.
The SiP also includes onboard memory resources – there is 384 kB of non-volatile Flash memory, of which 256 kB is available for user applications, 88 kB of data RAM and DMA controllers. There is also a selection of configurable external interfaces including I2C, UART and dual SPI (Master/Slave) that enhance flexibility for a wide range of applications.
The RSL10 SiP can support Bluetooth Low Energy technology as well as other 2.4 GHz proprietary and/or custom protocol stacks. The support of Firmware-Over-The-Air (FOTA) allows manufacturers to provide updates and add additional functionality after deployment.
Onboard power management is a key requirement for SiP devices for enabling IoT applications. The RSL10 is currently the lowest power Bluetooth Low Energy radio on the market. When operating in receive mode, it consumes just 7 mW and reduces to 62.5 nW in deep sleep mode. This allows designers to reduce system size and weight by minimizing the number of required external components.
Wide operating voltage range is a further valuable feature for designers and broadens the number of potential applications for devices like the RSL10. A supply voltage range of 1.1 to 3.3 V allows the use of either 1.2 or 1.5 V batteries without the need for an external DC/DC converter. It also allows for extended useful working time as the battery voltage decreases.
Alongside the benefits of powerful and highly integrated solutions, engineers now often seek tools and assistance to help them complete their designs in the fastest possible time at the lowest cost and with minimal specialist resources. ON Semiconductor offers a suite of useful tools to further simplify and speed up designs using its RSL10.
The RSL10 Software Development Kit (SDK) provides a complete Eclipse-based Integrated Development Environment for developing ultra-low-power Bluetooth Low Energy applications. The kit includes support for Keil uVision and IAR Embedded Work Bench alongside a wide range of abstraction, drivers and sample applications, FreeRTOS, and a Firmware Over the Air (FOTA) mobile application.
Providing a complete node-to-cloud solution, the Bluetooth IoT Development Kit (B-IDK) has a modular design that includes a wide range of sensors and actuators. Software support is provided in a convenient CMSIS-Pack that adds a higher level of functionality to the RSL10 SDK. The B-IDK CMSIS-Pack contains sensor drivers, cloud support and documentation specific to the B-IDK platform. In addition, a mobile app allows control of the hardware and publishing and subscribing (MQTT) to sensor and actuator data from multiple popular cloud services.
Sensor development kits can also be an extremely useful resource for those working on IoT designs, perhaps for the first time. The RSL10 Sensor Development Kit contains over 10 sensing elements covering light, environment, sound, location and motion to help engineers get from concept to solution quickly and with fewer design respins.
The ability to communicate utilizing popular protocols and operate from ultra-small power sources, are critical success factors for IoT devices. Technologies such as Bluetooth Low Energy have evolved over time from being a basic way of connecting peripherals in very close proximity to the de facto technology to meet the highly optimized needs of the IoT.
Devices such as the RSL10 SiP ease the design task by integrating the external components and RF sub-system in a small, highly power efficient package. Combining this with the extensive support tools available helps designers add low-power Bluetooth Low Energy functionality to IoT nodes with minimum risk, cost and time.
Pavan Mulabagal is part of the IoT strategy and marketing team at ON Semiconductor. In this role, he’s responsible for driving IoT initiatives, customer and partner engagements, and evangelizing ON Semiconductor’s IoT products and solutions spanning everything from sensors to connectivity solutions, actuators and SoCs. Prior to ON Semiconductor, Pavan spent close to a decade at Qualcomm where he created product and technology roadmaps, established strategic partnerships, and formulated go-to-market strategies. During his 17+ years in the high-tech industry, Pavan has launched a number of wearable, mobile, consumer and networking products. Pavan holds an MBA from Haas School of business, Berkeley and a BSEE from the Indian Institute of Technology.