BRISTOL Wireless chip specialist CSR plc (Cambridge, England) has said it has collaborated with Intel Corp. to redesign how the CSR integrated Bluetooth chip interacts with a laptop PC.
The way the integrated USB Bluetooth device as been designed has been preventing laptops from entering into certain power-saving modes because of a need for frequent polling of status. In essence CSR's firmware and software corrects this failure and this allows laptops to meet their power saving potential.
CSR has developed Bluetooth firmware and complementary Windows software which implements an Intel-developed power-saving technique called USB Sideband Deferring. The objective is to eliminate the power drain caused by frequent polling of the Bluetooth chip by the USB subsystem. Laptops employing the technology from CSR and Intel could save up to one watt in power consumption, which could equate to an extra 30 minutes of battery life, CSR claimed.
Intel mobile processors implement many techniques to save power.
One of the most important techniques Intel mobile processors implement to save power is to switch to low-power sleep states when idle. An important sleep state is called C3. An integrated USB Bluetooth device can prevent the processor from entering the C3 state because it needs to be constantly polled to check whether it has any data to send to the system, according to CSR. This constant polling prevents entry into C3, the company said. Bluetooth APM lowers power consumption by making sure that the Bluetooth device is only polled when it has data to pass to the system. The rest of the time the processor is free to enter C3 as it normally would.
As a result Bluetooth Advanced Power Management (APM) can now be designed into Intel mobile processor-based laptops.
"CSR’s implementation of Intel’s USB sideband deferring technology makes this possible while saving system power," said Kamal Shah, manager, Mobility Enabling Initiative, Mobile Platforms Group at Intel in a statement issued by CSR.
"By working closely together, CSR and Intel have readdressed the way that Bluetooth interacts with the main system and therefore how much power is consumed within the notebook PC." said Bill Nayavich, PC market manager at CSR, in the same statement. "This collaboration between Intel and CSR allows us to offer OEMs an innovative approach to enabling longer battery life for laptops."
Bluetooth Advanced Power Management is available now using firmware for the flash memory-based BlueCore4-External. Equivalent ROM-based silicon will be sampling to lead customers in September 2008.
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