Ultra-low power mode for a low-cost force-sensing device
First Claim
1. A system comprising:
- a plurality of processors including at least a microcontroller and a high-power application processor each configured to be placed in a suspended state; and
analog front-end circuitry configured to;
convert an analog signal generated by a force sensor into a digital signal;
store samples of the digital signal in a buffer;
filter the digital signal based on deviations in a rate of change of the signal from a baseline value; and
responsive to the filtered digital signal passing one or more threshold values, wake the microcontroller from the suspended state to analyze the samples of the digital signal in the buffer to determine whether the digital signal corresponds to a human gesture, the microcontroller configured to wake the high-power application processor from the suspended state to process the human gesture based on the digital signal being recognized as a human gesture.
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Abstract
Techniques and apparatuses are described that provide an ultra-low power mode for a low-cost force-sensing device. These techniques extend battery life of the device by minimizing power consumption for potential wake-up events. To do this, a high-pass filter (e.g., differentiator) is used to evaluate sensor signals in a time domain to provide an estimate of a rate of change of the signal. When the rate of change of the signal deviates from a baseline value by a threshold amount, then a microcontroller is woken to evaluate a large number of historical samples, such as 200 or more milliseconds worth of historical data. If a human gesture is not recognized, then the microcontroller returns to an idle state, but if a human gesture is recognized, then a high-power application processor is woken to execute an application configured to perform an operation mapped to the human gesture.
8 Citations
20 Claims
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1. A system comprising:
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a plurality of processors including at least a microcontroller and a high-power application processor each configured to be placed in a suspended state; and analog front-end circuitry configured to; convert an analog signal generated by a force sensor into a digital signal; store samples of the digital signal in a buffer; filter the digital signal based on deviations in a rate of change of the signal from a baseline value; and responsive to the filtered digital signal passing one or more threshold values, wake the microcontroller from the suspended state to analyze the samples of the digital signal in the buffer to determine whether the digital signal corresponds to a human gesture, the microcontroller configured to wake the high-power application processor from the suspended state to process the human gesture based on the digital signal being recognized as a human gesture. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for managing an ultra-low power mode for a mobile device, the method comprising:
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generating an input signal based on detection of a force applied to a housing of the mobile device when the mobile device is in a low-power idle state; storing samples of the input signal in a buffer; filtering the input signal based on deviations from a baseline rate-of-change of the input signal; triggering an interrupt based on the deviations passing one or more threshold values; and waking a microcontroller from the low-power idle state based on the interrupt to analyze the samples in the buffer and determine whether the input signal corresponds to a human gesture. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A computing device comprising:
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one or more sensors configured to detect a force applied to a housing of the computing device; an analog-to-digital converter configured to generate a signal based on the detected force; a buffer configured to store samples corresponding to the signal; a high-pass filter configured to filter the signal based on deviations in a rate of change of the signal relative to a baseline value; a comparator circuit configured to trigger an interrupt based on a deviation in the rate of change of the signal being greater than or lesser than a threshold value; and a microcontroller configured to wake from a low-power idle state based on the interrupt and read the samples in the buffer to determine whether the signal corresponds to a human gesture, the microcontroller configured to wake a high-power application processor from a low-power idle state responsive to the signal being recognized as a human gesture. - View Dependent Claims (17, 18, 19, 20)
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Specification