Bluetooth low-energy technology for IoT applications

By Jakob Nielsen, Product Line Manager, ON Semiconductor

As connected technology becomes more advanced, more dependable, and consumes less power, greater opportunities for IoT adoption are becoming possible and emerging in markets including health care and industrial. Although these industries seem very different, they share key commonalities and design requirements at their core.
By using sensors or objects to send data to a cloud server, companies or individuals are able to analyze the provided data and derive information about use-patterns or behaviors that the sensors and objects monitor or influence. This information can then subsequently be applied to make some sort of improvement to processes or operations.

In the health and wellness sector, new approaches are emerging that enable doctors or health care practitioners to remotely monitor adherence to a treatment plan. By adding sensors to a medical device that can detect when it is being used by the patient and subsequently transmit this information to the practitioner and/or the patient themselves, it is possible to track or send alerts regarding whether the prescribed treatment is being followed. This provides the medical practitioner with the ability to adjust the prescription and improve patient outcome, and all this can be done remotely.

In the industrial space, connected technology can be used to help manufacturers by enabling them to collect data from equipment or other devices. For instance, the industrial sector is currently using IoT solutions where sensors monitor critical attributes of manufacturing equipment during the normal operation cycle. Here, sensors can provide data or alerts about the operational state of the equipment for characteristics such as temperature and pressure, for example. This allows the manufacturer to optimize production, decrease operating costs, and even support predictive maintenance to reduce downtime and its associated costs.

IoT system topology
Regardless of industry or application, the general topology of most IoT systems is the same (as outlined in Figure 1). Using the health care example, the connected device could be an application like a glucose monitor, and the local user would typically be the patient’s smartphone. The phone provides the data to the internet, where an analysis facility interprets the data according to a predefined algorithm. At any time, a remote user can access the data presented by the analysis facility using a standard web browser or a phone application.

The importance of retrofit to IoT traction
From an implementation perspective, an application developer is often faced with the challenges of having to add IoT technology into an existing infrastructure. This scenario represents a very large portion of the potential market for the IoT. Consider a company wanting to connect its machinery to the internet to take advantage of data collection and analysis in order to optimize production. Due to the added costs and the risk of disruption, the company is unlikely to go out and purchase new IoT-ready machinery; rather, it is easier, less disruptive, and much less expensive for them to retrofit existing machinery with IoT hardware, wireless communication capability, and software.
Prior to IoT implementation, the machinery is likely to have stored data internally during its normal operation cycle. Occasionally, an operator may have connected a download device to the machinery via a cable to copy this data to a PC or specialized handheld unit. After download, the operator would typically connect the device to a PC connected to the internet or to another data storage facility and re-upload the data.
In these cases, it is simplest for an IoT application developer to take advantage of using existing protocols to download data or communicate between the machinery (or data storage facility) and a pre-existing download device.

Primary IoT design considerations
Although there is no shortage of semiconductor solutions on the market for IoT applications, design engineers must still make crucial decisions related to their system-level design needs. Considerations such as power sources and consumption, device lifetime, communication range, data throughput, application physical size, maintainability needs of the application in the field, and existing communication infrastructure all play important roles in how device selections and design decisions are made. More practical engineering considerations such as ease of design-in and implementation, as well as flexibility for future generations of the application, are additional selection criteria.
In many cases, the connected device is small and battery-powered; this can make power consumption/battery longevity the primary design concern. Engineers often have to meet a certain number of hours of active device lifetime before the battery runs flat, which, in turn, propagates through to the selection of power management and wireless system design. Likewise, for this type of connected device, communication to a local user often happens through Bluetooth Low Energy technology as this is the standard wireless communication protocol built into most smartphones.

Semiconductors — an IoT-enabling technology
The rapidly growing and evolving IoT market segment for Bluetooth-Low-Energy-based wireless connectivity is heavily reliant on enabling semiconductor technologies, with a number of key high-level characteristics that align with the design considerations in the previous paragraph. High data throughput, ultra-low power operation, and a highly integrated, small form factor design to address the shrinking space envelope that is especially prevalent in the wearables sector should be the hallmarks of an IoT semiconductor offering.

ON Semiconductor’s RSL10 is an example of a device optimized for Bluetooth Low Energy applications for the IoT. This recently launched SoC offers communication speeds twice as fast as previous generations and a 6-mm2 footprint that manages to integrate a Bluetooth Low Energy radio, Digital Signal Processor (DSP), and associated functionality all around a powerful ARM Cortex-M3 processor. This facilitates the local processing of data from connected devices prior to it being sent to the cloud.
With so many IoT “opportunities” being powered by batteries — typically small ones of between 1 and 3 V — frugal use of power is high on the wish list for devices, including semiconductors, used for implementing an IoT solution. In the case of the RSL10, on-chip DC/DC conversion, as well as regulation, ensures optimization of power use as well as presenting the opportunity to feed other parts of the system with the appropriate voltages.

Bluetooth Low Energy radio SoCs — including ON Semiconductor’s RSL10 — are “awake” to transmit and receive data only for short intervals; the remainder of the time, they sit in a sleep mode. Minimizing power use without impeding performance in these three states and especially in sleep mode, where most time is spent, is the key to battery longevity.

The future of IoT
Because of its widespread availability in smartphones, Bluetooth Low Energy has played a pivotal role in the IoT revolution — particularly for short-range wireless communication in devices in which battery life is critical.
By offering the industry’s lowest power consumption during Peak Receiving and Deep Sleep Mode, ON Semiconductor’s RSL10 has brought Bluetooth Low Energy technology to a new low level in terms of power consumption. This, combined with added flexibility and processing power in a highly integrated SoC format, will help bring the IoT to a broader range of applications.

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