Fingerprint Sensor SPI Control for Power Savings
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Solution Overview
Problem
Fingerprint recognition systems in smart terminals often maintain a serial peripheral interface (SPI) in an open state for extended periods when no fingerprint is detected, leading to increased power consumption due to idle states.
Innovation Solution
Implement a method and apparatus for controlling the SPI of a fingerprint sensor by detecting fingerprint signals, such as changes in capacitance or light reflection, to open the interface only when a valid fingerprint signal is detected, and closing it when no signal is present for a predetermined time, thereby reducing unnecessary power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the SPI is maintained in an open state for extended periods when no fingerprint is detected, then the system is ready to transmit signals quickly, but power consumption increases due to idle states
Solution Approach 1:
The SPI interface dynamically changes its state between open and closed based on fingerprint detection status. The controller opens the SPI when a fingerprint signal is detected and closes it when no signal is present, making the system adaptable to actual usage conditions rather than maintaining a fixed state
Solution Approach 2:
The system employs periodic fingerprint signal detection to control SPI state transitions. The controller continuously monitors for fingerprint signals and periodically adjusts the SPI state accordingly, creating a rhythm of open/closed states that balances readiness with power conservation
2Use of energy by moving object
If the SPI is opened only when a fingerprint signal is detected, then power consumption is reduced, but signal transmission may be delayed
Solution Approach 1:
The system performs preliminary fingerprint signal detection before opening the SPI interface. By detecting the fingerprint signal in advance and then opening the SPI immediately upon detection, the system prepares the transmission path proactively, minimizing actual transmission delay while maintaining power savings during idle periods
3Use of energy by moving object
If the SPI remains closed to save power, then energy efficiency improves, but the system cannot respond quickly to fingerprint signals
Solution Approach 1:
The system implements a feedback mechanism where the controller continuously monitors fingerprint sensor output and uses this feedback to determine when to open the SPI interface. This closed-loop control ensures the SPI is opened at the appropriate moment to maintain reliable fingerprint signal detection while minimizing power consumption during idle states
Data Source
AI summary
The present disclosure provides a method and an apparatus for controlling a serial peripheral interface of a fingerprint sensor, and a mobile terminal. The method includes: detecting a fingerprint signal via a fingerprint sensor; and when the fingerprint signal is detected, opening the serial peripheral interface of the fingerprint sensor.