Microphone Array Wake-Up Latency via Direct Bus Signaling
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Solution Overview
Problem
Existing microphone systems in portable devices experience high power-up latency due to the need for a central processor to activate multiple microphones, which consumes significant system power and delays the detection of acoustic inputs.
Innovation Solution
A microphone array with a common bus allows the first active microphone to directly send 'wake up' commands to other microphones, bypassing the central processor, thereby reducing power-up latency and conserving battery power by minimizing signaling between the processor and microphones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a central processor activates multiple microphones, then the microphones can detect acoustic input sounds, but the power-up latency increases and system power consumption increases
Solution Approach 1:
The system divides the microphone array into one active microphone and multiple sleep mode microphones. The active microphone remains powered on to detect acoustic signals and send wake-up commands, while other microphones stay in low-power state. This segmentation allows rapid activation of specific microphones based on acoustic event location, reducing overall power-up latency compared to activating all microphones simultaneously.
Solution Approach 2:
One microphone is kept in advance in an active state as a sentinel, performing preliminary acoustic detection. When it detects an acoustic event, it immediately triggers wake-up commands to other microphones via the common bus. This preliminary action eliminates the need for all microphones to wake up from sleep mode simultaneously, reducing power-up latency.
2Reliability
If a central processor activates multiple microphones, then the microphones can detect acoustic input sounds, but the system power consumption increases
Solution Approach 1:
The microphone system is segmented into active and sleep mode components. Only one microphone consumes full power at a time to perform acoustic detection and command generation, while others consume minimal power in sleep mode. This segmentation dramatically reduces overall system power consumption compared to having all microphones active or requiring central processor activation for each microphone.
Solution Approach 2:
The active microphone autonomously generates and transmits wake-up commands to other microphones through the common bus without requiring central processor intervention. This self-service capability eliminates the power consumption associated with processor involvement in microphone activation, reducing overall system power usage while maintaining detection reliability.
3Reliability
If the central processor sends commands to activate other microphones, then the microphones can be activated, but the signaling complexity and processor involvement increase
Solution Approach 1:
The wake-up command generation and transmission function is extracted from the central processor and implemented directly in the active microphone's logic circuitry. The active microphone now independently generates wake-up commands and transmits them via the common bus to other microphones. This extraction eliminates the need for processor involvement in the activation signaling path, reducing signaling complexity and processor load while maintaining activation reliability.
Solution Approach 2:
The common bus serves as an intermediary communication channel between microphones, replacing the need for processor-mediated signaling. Wake-up commands are transmitted directly over the existing common bus infrastructure that connects all microphones to the codec, eliminating complex processor intervention while leveraging the already-present communication pathway.
Data Source
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AI summary
A method includes generating a command at a first microphone and sending the command from the first microphone to a second microphone. The command is sent to the second microphone via a bus that is coupled to the first microphone and to the second microphone.