Software lets radio chip merge Zigbee and Bluetooth networks

By Richard Quinnell, editor-in-chief

In the Internet of Things, wireless communications choices are legion — especially in the building automation market. Developers are challenged to decide which of several competing networking standards will meet their application needs while also appealing to the market. By blending two popular options into a single device, Silicon Labs has just made that choice easier. 

It’s a long-standing battle among building networking standards to become the preferred option among consumers. The problem that developers have in choosing among the competing standards is that the right technical choice might not be the right market choice. Each contender has its advantages and drawbacks. Bluetooth Low Energy (BLE) is widely available on smartphones, which are the control devices that most consumers prefer, but it has limited range and scalability for building automation applications. Wi-Fi is available in virtually every home and office, so the base network is already in place, but Wi-Fi in an IoT device is overkill for most applications and is more expensive and power-hungry than other options. Zigbee is a nice match for building automation applications from a power and performance perspective, but Zigbee devices require users to also have a gateway or hub device to interact with the network. 

It’s possible, of course, for a developer to put two wireless devices in their design and simultaneously support multiple networking standards. This gives consumers the option of which type of network to provide and increases the avenues that consumers have for interacting with their devices. But this adds to the cost and power demands of a design, which makes it less attractive to consumers.

Silicon Labs is now offering a solution to these challenges. The company has released new software  for its Mighty Gecko  family of wireless SoCs and related modules that lets the radio simultaneously serve as both a Zigbee and a BLE link. Both networks use the same carrier frequency of 2.4 GHz, but the modulation and protocols differ. The new software can automatically switch the module’s operation between the two modes while maintaining independent protocol stacks, creating a time-multiplexed, dual-channel communications link that appears to application code as two independent, simultaneous channels. The channels support Zigbee routing, Bluetooth connection, and Bluetooth beaconing operations.

There are several critical factors behind this achievement. One is that the company has developed its own software for the operating system (Micrium) and protocol stacks, which run on a common radio interface layer (RAIL). The in-depth understanding and control that this ownership affords, in turn, has let the company develop intelligent radio scheduling software that mitigates the potential problems with network multiplexing. The scheduler ensures that the lower-bandwidth and more forgiving Zigbee traffic yields priority to the more deterministic Bluetooth traffic. Because the Bluetooth traffic is high-bandwidth, however, the deference is short-term, which allows Zigbee traffic to flow with minimal interruption. 

The result is wireless connectivity that expands the opportunities for network developers. A combined Zigbee/BLE device, for instance, allows building managers to seamlessly add new Bluetooth beacons to their operation as they expand their Zigbee automation network without requiring a separate network setup. Consumers will be able to control their Zigbee home automation devices using their smartphone’s BLE without needing a gateway or protocol translator device. And Zigbee devices can use the faster BLE channel to speed their software updates.

The company supports its multiprotocol wireless SoCs and modules with its own IDE — Simplicity Studio — and tools for packet trace and network analysis, energy profiling, and application configuration. It is also offering a starter kit with multiple radio boards, SDK, and integrated debug.