Abstract

Wrist-worn wearable devices, such as smartwatches and fitness trackers, with an always-on display (AOD) often connect to other devices via a wireless link or radio connection, using sleep schedules to save energy. However, this causes a noticeable lag when a user touches the screen. At the same time, accidental brushes from clothing can trigger false alarms that drain the battery if the device wakes up too often. This publication describes techniques to optimize latency and power consumption by utilizing an always-on (AON) capacitive hover front-end or touchless gesture detection sensor that intelligently drives low-power wireless communication protocol (e.g., Bluetooth Low Energy (BLE)) link states. Furthermore, the techniques described can track the rate of change in capacitance to detect approaching objects regardless of environmental conditions like thick gloves or moisture and anticipate user actions to either briefly speed up the connection (with an automatic reset for false alarms) or precisely hold a link window open. Crucially, the techniques described run locally on the low-power AON domain and Bluetooth controller, allowing the device's main processor to remain completely asleep to save battery.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

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