Bluetooth Sleep Time Control via Wake-Up Timing Alignment
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Solution Overview
Problem
Bluetooth devices experience inefficient power consumption due to asynchronous wake-up processes, leading to unnecessary activation periods between sleep and active modes, as the wake-up instant may not align with the internal clock signal, resulting in prolonged power usage without performing Bluetooth transactions.
Innovation Solution
The method employs a sleep clock rate of 1.6 KHz derived from the 32 KHz or 32.768 KHz clock signal to align the wake-up instant with the 625 µs timing signal, extending the sleep duration and reducing active time without transactions, by calculating sleep time using the sleep fine count and base count signals, and accounting for wake-up overhead such as crystal warm-up time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the Bluetooth device wakes up immediately upon receiving an external wake-up signal, then the response time is minimized, but the power consumption increases due to misalignment with the 625 µs timing signal causing prolonged active periods without transactions
Solution Approach 1:
The device performs preliminary action by pre-calculating the optimal wake-up time that aligns with the 625 µs timing signal boundary before actually waking up. The wake-up logic determines ahead of time when the next valid timing slot will occur and schedules the wake-up to coincide exactly with that moment, thus avoiding prolonged active periods without transactions while maintaining timely response to external wake-up signals
Solution Approach 2:
The invention changes the wake-up timing parameter from immediate activation upon receiving an external signal to a delayed activation that aligns with the 625 µs timing signal boundary. By adjusting the wake-up time parameter to match the Bluetooth protocol's timing requirements, the device eliminates unnecessary active periods and reduces power consumption while still responding promptly to external wake-up signals
2Use of energy by moving object
If the Bluetooth device extends sleep duration to maximize power savings, then power consumption is reduced, but the wake-up alignment with timing signal becomes asynchronous causing inefficiency
Solution Approach 1:
The wake-up logic uses feedback by continuously monitoring the 625 µs timing signal and using it as a reference to determine the optimal wake-up moment. The system feedbacks the timing signal boundary information to the wake-up logic, which then adjusts the wake-up time to align precisely with the timing signal, ensuring both power efficiency and reliable timing alignment
Solution Approach 2:
The device performs preliminary calculation of the wake-up time based on the 625 µs timing signal boundary before actually extending the sleep duration. By predetermined the alignment point in advance, the device can confidently extend sleep without risking misalignment, thus achieving both power savings and timing reliability
Data Source
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AI summary
A method and apparatus for extending the sleep time for a Bluetooth transceiver circuit uses a fine count signal and a base count signal during the sleep mode, followed by an interval that accounts for wake-up overhead and preparation for the next active mode. The wake-up to active mode is aligned with the timing signal that defines the communication slots in the Bluetooth communications. The extension of the sleep mode until a beginning of a communication slot in active mode is accomplished for wake-up processes that are initiated by an external trigger event as well as for wake-up processes that are initiated as a result of an internal timer. Power consumption is reduced because the circuit does not wake up to active mode before communication can be carried out in a communication slot.