Until recently, ANT+ and Bluetooth low-energy wireless technology were simply incompatible, forcing developers and end users to choose one or the other. Now such decision-making will likely fade into obsolescence thanks to a new multi-protocol system-on-a-chip (SoC) that offers concurrent ANT+ and Bluetooth low energy wireless communication. According to developer Nordic Semiconductor, the nRF51922 SoC is the first to offer this design advantage (see the figure).
ANT+ wireless technology allows monitoring devices to talk to each other, ensuring that users of ANT+ products can enjoy efficient access and use of data. It's all about interoperability, which simply means that such products from multiple brands work together.
ANT+ is a well-proven protocol and silicon solution for ultra-low-power (ULP) practical wireless-networking applications, facilitating interoperability between ANT+ Alliance member devices and automatic transfer and tracking of sensor data. It also defines device profiles, which is important because it specifies data formats, channel parameters, and network keys.
Bluetooth low-energy technology extends wireless connectivity to applications powered by coin-cell batteries in consumer products. It operates in the internationally accepted 2.4-GHz Industrial, Scientific and Medical (ISM) band, and maintains a physical-layer bit rate of 1 Mbit/s over a range up to 15 meters.
With this specification, Bluetooth v4.0 chips are able to integrate Bluetooth low-energy functionality into an existing classic Bluetooth controller. OEMs also can use current classic Bluetooth technology chips with the new Bluetooth low-energy stack.
Nordic Semiconductor believes the SoC makes it possible to use one or both protocols concurrently in a product, enabling multiprotocol accessories and compatibility with ANT+ and Bluetooth Smart Ready hubs. The device, which is compatible with existing nRF51 series designs, features the company’s new S310 SoftDevice that combines the ANT+ and Bluetooth low-energy stacks in a single software framework. The S310 also gives designers the same autonomous, secure, and event-driven application interface as existing Nordic SoftDevices.
Nordic S110 (Bluetooth low energy) and S210 (ANT+) SoftDevice users will find that the S310 has pin-compatible hardware and a familiar interface. As a result, customers that already have an nRF51 Series ANT+ or Bluetooth low-energy product will be able to keep existing hardware design and firmware. All that’s needed is firmware support for the new protocol stack when implementing the nRF51922.
The architecture of the nRF51 SoCs is designed to cut current consumption and enable single-chip implementations of various wireless applications. It includes a low-power 32-bit ARM Corte M0 processor with 2-µs startup time that minimizes active time and improves code density. Individual system blocks can be powered independently, and clocks can be controlled autonomously based on activity level. In addition, peripherals such as radio, timers, and I/O are able to interact autonomously with each other without involving the processor.
Another design advantage of this architecture is its separation between protocol stack and user-application code. The stacks are delivered as a pre-compiled binary or pre-programmed on devices. They’re 100% asynchronous and event-driven, and provide thread-safe Supervisor Call-based application program interfaces to the application layer.