Coming soon: Bluetooth devices with 10 year battery life

Stuart Corner
Tuesday, 15 April 2008 05:06

Business IT - Technology

UK-based chip maker CSR has demonstrated the first ultra-low power bluetooth chip. The technology, previously known as Wibree, promises to enable wireless data communications from small devices powered by button sized batteries typically used in wrist watches with standby battery life of up to ten years.

Because of its low power requirements, ULP Bluetooth is set to significantly broaden the applications for Bluetooth. It has been developed for small devices that need to send short data bursts intermittently. According to CSR, its ULP Bluetooth silicon consumes 10 times less power than standard Bluetooth on standby and transfers data packets 50-times faster than standard Bluetooth, so is able to transfer the same amount of data as standard bluetooth using only one fiftieth of the electrical energy. Its demonstration ICs support both standard Bluetooth (v.2.1) and ULP Bluetooth.

According to CSR, to connect devices in standard Bluetooth, the master device has to synchronise to a slave device by paging a specific device using up to 32 frequencies, it then issues FHS (frequency hopping spectrum) packets, then it polls the slave before negotiating connections at both the link manager and L2CAP layers – all of this essential connection process takes place before actually sending data.

CSR says that, while this overhead is essential for standard Bluetooth carrying more complex data protocols, it does slow down the connection. When ULP Bluetooth is used, in a wireless heart rate monitor for example, the monitor simply 'advertises' itself to the control/reader using just three frequencies. It then connects, sends its very short burst of data and then switches off again. This allows ULP Bluetooth to achieve data transfer 50-times faster than standard Bluetooth; less time spent transferring data means the ULP radio spends less time active and battery life is prolonged.

The technology was previously known as Wibree. The Bluetooth Special Interest Group and the Wibree Forum announced in June 2007 that the Wibree technology, then still under development would become a low power version of bluetooth.

The move ended a curious phase in Bluetooth's history, in which the unanswered question was why development the functionality provided by Wibree had not been undertaken within Bluetooth in the first place, as several Wibree backers, such a Nokia, had been early players in and continued to be active in Bluetooth developments. The need for a low power version of Bluetooth, suitable for small devices like watches powered by 'button' batteries, had been evident for some time.