Embedded Controller Wake-Up via BIOS Handshake
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Solution Overview
Problem
Electronic devices face challenges in managing power consumption during User Absent Mode (UAM) as existing technologies take too long to wake up the embedded controller (EC) from low power mode, leading to inefficiencies and loss of keystroke data.
Innovation Solution
Implementing an out-of-band handshake between EC firmware and BIOS using GPIO signals to manage the EC's low power mode, allowing for efficient wake-up and data interface activation without modifying existing operating system code, utilizing BIOS to act as a proxy and handle OS requests until the LPC interface is functional.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the EC enters low power mode to conserve battery power, then power consumption is reduced, but the wake-up time becomes too long causing keystroke data loss
Solution Approach 1:
The BIOS performs preliminary actions by staying in a low-power state and quickly activating the LPC interface upon detecting OS access attempts, rather than allowing the EC to remain fully active. This preliminary setup enables fast wake-up responses while maintaining power efficiency.
Solution Approach 2:
The BIOS acts as an intermediary between the OS and the EC during low-power mode transitions. It monitors for OS access attempts and mediates the wake-up process by activating the LPC interface and handling the transition, preventing data loss while managing power consumption.
2Speed
If the EC remains active to respond quickly to OS requests, then response speed is improved, but power consumption increases
Solution Approach 1:
Instead of continuous EC activity, the system uses periodic monitoring by the BIOS for OS access attempts. The EC can enter low-power mode periodically, and the BIOS periodically checks for wake events, achieving energy efficiency while maintaining responsiveness when needed.
Solution Approach 2:
The BIOS performs self-service by monitoring its own state and automatically activating the LPC interface when it detects OS access attempts during EC low-power mode. This eliminates the need for continuous EC monitoring while maintaining system responsiveness.
3Use of energy by moving object
If the LPC interface is turned off to save power, then energy efficiency is improved, but the time to activate the interface increases
Solution Approach 1:
The BIOS performs preliminary actions by detecting OS access attempts before the EC fully wakes up and quickly activating the LPC interface. This preliminary detection and activation sequence reduces the overall time the interface needs to remain inactive while maintaining energy efficiency.
4Loss of information
If the EC wakes up quickly from low power mode, then data loss is prevented, but power consumption increases
Solution Approach 1:
The BIOS serves as an intermediary that prevents data loss by monitoring for OS access attempts and quickly activating the LPC interface when needed. This mediation allows the EC to remain in low-power mode longer without risking data loss, as the BIOS handles the wake-up coordination.
Solution Approach 2:
The BIOS performs preliminary detection of wake events and prepares the LPC interface for quick activation. This preliminary action ensures that when the EC needs to wake up, the interface is already ready, preventing data loss without requiring the EC to maintain higher power states.
Data Source
AI summary
An electronic device may be provided that includes a first controller, a second controller, and a bus to connect between the first controller and the second controller. The electronic device may also include a first signal line between the first controller and the second controller, and the first controller to provide a first signal on the first signal line to the second controller to wake up the second controller from a low power mode.