Bluetooth Smart design for Rezence Wireless Charging

December 20, 2013 // By Graham Prophet
A wireless charging application enables charge pads with support for simultaneous charging of up to eight devices; Nordic Semiconductor has also announced the S120 8-link central role Bluetooth low energy SoftDevice (protocol stack) for its nRF51822

Ultra low power (ULP) RF specialist Nordic Semiconductor ASA (OSE: NOD) has introduced the S120 8-link central protocol stack and the nRF51 Wireless Charging Software Development Kit (SDK) for wireless charging applications based on the Rezence standard, developed and maintained by the Alliance for Wireless Power (A4WP).

Rezence is a wireless power transfer technology and specification based on the principles of magnetic resonance. Embracing the concept of spatial freedom, Rezence extends wireless power applications "beyond the mat" and accessories market into almost any mobile device or surface.

S120 is an 8-link central role Bluetooth low energy SoftDevice for the nRF51822 System-on-Chip (SoC). The nRF51 Wireless Charging SDK includes services/profiles for a Rezence Power Transmitting Unit (PTU) and Power Receiving Unit (PRU) as well as state machine examples. S120 together with the nRF51 Wireless Charging SDK provides a solution for the Out-of-Band (OOB) signalling part of a Rezence charge pad. With the support for 8-link concurrent link, a Charge pad based on nRF51822 / S120 can support simultaneous charging of up to eight devices. The existing S110 peripheral role Bluetooth low energy SoftDevice combined with the SDK provides the same solution for a Rezence rechargeable device.

Unlike older technologies, Rezence uses the principles of magnetic resonance, which brings a number of benefits to the wireless charging ecosystem. Bluetooth Smart has been chosen by Rezence as the technology for OOB charging management functions for Rezence applications. Rezence technology, its proponents claim, will be used to turn almost any surface into a wireless charging surface capable of powering any Rezence enabled mobile device. This includes retail environments, airports, automobiles, and home and office furniture. Rezence technology will also be integrated into other devices such as laptops and portable chargers, creating the world's first truly mobile wireless charging power sources.

The S120 SoftDevice includes all Bluetooth low energy protocol layers up to and including GATT/GAP. It supports multi-link central and observer roles, GATT server