Chips Simplify Low-Power Bluetooth Development

July 30, 2012
Nordic Semiconductor's new nRF51 series of wireless devices can implement Bluetooth low energy, ANT+ or proprietary wireless applications using an embedded ARM 32-bit Cortex-M0.

Nordic Semiconductor’s nRF51 ultra-low-power (ULP) RF ICs feature a new multi-protocol 2.4-GHz radio and a 32-bit ARM Cortex-M0 based processor. Add to that Nordic’s novel software architecture for Bluetooth low energy (BLE) and ANT system-on-a-chip (SoC) solutions, and you get a system that frees designers from the integration effort, complexities, and restrictions of chip vendor-supplied software frameworks. Customers, then, can develop their designs quickly and easily using the highly popular and familiar ARM Cortex programming environment.

A new and novel software architecture uses a unique and powerful separation between the protocol stack and user application code to achieve this benefit. This separation gives developers a clean boundary between the application and protocol stack. It also removes the need to struggle with the integration of application code as part of a vendor-imposed application development framework. Code development is now greatly simplified and accelerated. The risks associated with integrating the application and stack code are significantly reduced as well.

The first two flash-based ICs to debut in the nRF51 series are the nRF51822 multi-protocol BLE/2.4-GHz proprietary RF SoC and the nRF51422—the world’s first ANT SoC (see the figure). Developed by Canadian company Dynastream Innovations, which is owned by GPS radio company Garmin, the ANT proprietary wireless sensor network protocol facilitates the implementation of wireless mesh networks by providing guidelines for adta representation, signaling, co-existence, authentication, and error detection.

Nordic Semiconductor’s 2.4-GHz nRF51 ultra-low-power transcievers are available for proprietary protocols, ANT, and BLE. All of the models feature the ARM Cortex-M0 32-bit processor.

The multi-protocol 2.4-GHz radio features –92.5-dB RX sensitivity in BLE mode, up to +4-dBm output power in all modes, and sub-10-mA peak currents running off a 3-V coin cell battery. It also complies with the BLE (Bluetooth v4.0) specifications and supports non-concurrent and concurrent operation of a range of protocols including BLE, ANT, and proprietary 2.4-GHz RF. And, it offers full-range received signal strength indication (RSSI).

The nRF51 series SoC architecture is designed specifically to minimize average current consumption and enable single-chip implementations of a wide range of wireless applications. It boasts a powerful yet low-power 32-bit ARM Cortex-M0, an advanced and fine-grained power management scheme, and the Programmable Peripheral Interconnect (PPI) system. Its highly efficient EasyDMA radio interface includes flexible RAM mapped FIFOs. And, its flexible general-purpose I/O (GPIO) mapping eases printed-circuit board (PCB) design and helps minimize the number of routing layers.

The nRF51 series software architecture’s unique and powerful separation between the protocol stack and user application code gives application developers maximum flexibility, ease of development, and code safety. Protocol stacks such as BLE and ANT are delivered as a pre-compiled binary or pre-programmed on devices. Stacks are 100% asynchronous and event driven, while providing thread-safe supervisor SVC-based (supervisor call) application program interfaces (API) to the application layer

The very simple programming model doesn’t have any proprietary application framework or scheduler/real-time operating system (RTOS) dependencies, easing and accelerating code development. Also, the protocol stack and application code don’t have any link time dependencies, and they can be compiled and updated/programmed separately. Stacks are fully run-time protected, ensuring interoperability and reducing the risk of application bugs affecting stack operation. And, stacks are delivered as verified and qualified binary objects.

All nRF51 series ICs are code-compatible. Groups of ICs will be pin-compatible, so developers can keep and maintain a single code base that can be used and reused across a range of different projects. The nRF51822 and nRF51422 are sampling to lead customers now. General availability is scheduled for early September. Mass production is scheduled for the fourth quarter.

Nordic Semiconductor

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