Dotdot, using IEEE 802.15.4 compliant PHY
Collaboration between RF protocols Thread and Zigbee
The interconnectedness of all everyday objects in a single language


Concepts such as smart homes, connected homes, and home IoT are already becoming a reality around us. End-device manufacturers are also developing a variety of products, although they have so far focused on niche markets. In particular, the pace of adoption is expected to accelerate further as the use of voice command devices, such as Amazon's Echo and Apple's HomePod, increases.
Voice commands such as “Alexa, make the lights brighter” will facilitate the installation of systems that provide more sensor data, enabling Alexa to perceive the current space, recognize the surrounding environment, and control 'objects' through control channels. At the same time, as new wireless networking technologies are developed, continuously improved performance and flexibility, as well as excellent interoperability, must be provided.

Stable low-power wireless networks utilizing a mesh architecture are an attractive solution for both industrial and residential environments. For the technology to succeed, the product must be easy to operate, ready for immediate use, and defect-free. For example, in the case of homeowners, simple setup and stable operation must be enabled, taking into account the possibility of returns.

Similarly, while early adopters may be satisfied with incompatible devices from independent product families, an environment where products from multiple vendors can be used together must be established to maximize market potential. Therefore, standards are necessary.

We have already experienced a series of processes that enable the initiation of discussions on redefining standards. A brilliant idea at a moment preempts the technology to be used in the industry. There are various concepts regarding how to successfully commercialize such ideas. Fundamentally, these include grouping and collaboration, as well as competing against various other candidate technologies within a very short period of time to become the standard.

Compared to the historical standards 'wars' that unfolded during the development of technology-based products in other fields, low-power short-range wireless technology has faced relatively few difficulties relative to the benefits gained in this field. Bluetooth, ANT, Zigbee, and Thread, which provide proprietary and non-interoperable products using several of the same basic elements, have essentially established their own technological domains.


Maturity of standards
The basic idea behind low power consumption dates back about 20 years to using wireless protocols with slow data speeds for monitoring and product control.

The Zigbee Alliance, formed in 2002, has developed a wide range of standards and now has specifications suitable for various applications including home automation, lighting control, and smart energy. These member companies are currently establishing numerous products in global markets.

The Thread protocol, for which the Thread Group was formed in 2014, subsequently emerged in the field of low-power mesh networking. At the time of the group's formation, Arm, Samsung Electronics, and Qualcomm were listed as member companies. The Thread protocol is configured using the Internet Protocol (IPv6 addressing) and follows the 6LoWPAN standard. Like Zigbee, it utilizes IEEE 802.15.4 RF hardware and can use silicon from various vendors.

The Thread Group presented a protocol designed specifically for the home automation sector by embedding security features using existing IP-based techniques. It also introduced technology that requires 'battery-friendly' operation and can be 'used as an Internet standard on resource-constrained embedded devices.'

Meanwhile, in the field of home automation, a different approach to Bluetooth has emerged, targeting wireless point-to-point and device-to-device connectivity. Following its evolution into Bluetooth LE (Bluetooth Low Energy), the latest version (Bluetooth 5) has improved range and throughput (simultaneous operation is not supported), and supports mesh networking through the release of Bluetooth Mesh 1.0.

Bluetooth Special Interest Group (SIG) announced that it is making successful market strides as an option for mesh networks, particularly in the smart lighting sector. Bluetooth LE is natively supported on all smartphones and tablets currently in use, and Bluetooth SIG expects consumers to benefit from a familiar interface for controlling wireless home automation devices.


Implemented in a single language
While the Bluetooth SIG was improving products for home automation applications, Thread and Zigbee were not idle. Rather, these groups joined forces to support new standardization efforts, resulting in 'Dotdot'. Dotdot represents a movement to extend standardization to the upper application layers of the existing standards stack.
Dotdot is the result of efforts to create a single language capable of handling the connectivity attributes of all everyday objects with the goal of enabling IoT. It can be described as an 'open, general-purpose protocol' developed by Zigbee that uses an IEEE 802.15.4 compliant PHY (Physical Layer). At the same time, it runs on Thread's IP-based platforms.

Therefore, Dotdot is not a new standard. Zigbee regards it as a 'universal layer for threads and IoT (devices) as a universal platform.' Furthermore, Dotdot is not entirely newly developed, but is based on application-level functions already presented in the Zigbee specification, ZCL (Zigbee Cluster Library).

ZCL is now named Dotdot. Dotdot is a set of commands and attributes encompassing various Zigbee profiles that developers can use to implement interoperability with products from other manufacturers or to implement products utilizing public Zigbee profiles, such as Zigbee Smart Energy. Similar to the app store model used in smartphones, Dotdot enables applications to run on all appropriate compatible devices.

Developers are the ones who need Dotdot's feasibility the most. Therefore, they will have no difficulty writing interoperable device-level code. On the other hand, consumers will see the Dotdot brand name and logo, but they will not be very interested in technical details. This is because what matters to these consumers is that networked devices are simple, intuitive, and function properly.

Standard wars are resolved through various methods. Some competitors may disappear, or they may choose between collaboration and convergence. Alternatively, assistance may be obtained depending on the situation on the hardware side. As ICs continuously evolve in specific technology fields, experience accumulates and integration density increases. Early-generation product lines may consist of different silicon with distinct firmware/software standards. Subsequently, through iterative work, the optimal choice for the feature set configuration will be realized through multi-protocol components capable of accommodating all relevant protocols and standards, freeing developers from the risks of narrow options.
For example, Nordic Semiconductor's nRF52840 multi-protocol SoC is based on an Arm 32-bit Cortex-M4F microprocessor and integrates 1MB of flash and 256kB of RAM. This chip supports Bluetooth 5 and ANT, as well as configurable proprietary 2.4GHz operation. The nRF52840 also includes an IEEE 802.15.4 PHY to support all standard-based protocols.

This chip has obtained Thread 1.1 certification (OpenThread stack execution) and comes with the nRF5 SDK (Software Development Kit) for Thread and Zigbee. In addition, by supporting simultaneous operation between Zigbee/Thread and Bluetooth LE environments, it enables the implementation of the most flexible products suitable for next-generation residential, commercial, and industrial networks.

This article was written by Graham Prophet. Prophet previously worked as a reporter for EDN Europe and is currently working as a freelance journalist in the electronics field.