Bus Interface Repeater for Low-Power Remote Wake-Up Detection

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Solution Overview

Problem

The USB host in low-power mode is required to periodically check for device activity, consuming power due to the need to keep its physical interface unit powered on, despite no communication occurring.

Innovation Solution

A repeater is inserted between the host and device to monitor bus activity, detecting remote wake-up events and generating interrupts for the host, allowing the host to enter a low-power state without modifying its wake-up procedure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the host checks for device activity every 100ms during low-power mode, then the host can detect device wake-up events, but the host must keep its physical interface unit powered on, increasing power consumption

Engineering Contradiction:

Improvedevice activity detectionVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The repeater acts as an intermediary device between the host and USB device. It monitors the USB bus for wake-up events and generates interrupts to notify the host, allowing the host's physical interface unit to remain powered off during low-power mode while still detecting device activity through the repeater's interrupt signals

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If the host enters low-power mode to conserve energy, then power consumption is reduced, but the host cannot detect device wake-up events without keeping the physical interface unit powered on

Engineering Contradiction:

Improvepower consumptionVSAvoidwake-up event detection

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The repeater serves as a mediator that fully powers the USB physical interface, monitoring the bus for wake-up events, and generates interrupts to notify the host when devices wake up, enabling the host to remain in low-power mode while maintaining reliable wake-up detection through the repeater's interrupt mechanism

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If a repeater is inserted between host and device to monitor bus activity, then the host can enter low-power state without modifying wake-up procedure, but the system complexity increases

Engineering Contradiction:

Improvepower consumptionVSAvoidsystem structure

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The repeater is designed as a transparent intermediary that monitors USB bus activity and generates standardized interrupts compatible with existing host wake-up procedures, allowing the host to enter low-power mode without modifying its wake-up logic while the repeater handles all monitoring and notification functions in the background

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20260079560A1Mechanism for Saving Power on a Bus Interface

Publication Date: 2026.03.19 APPLE INC

AI summary

Systems, apparatuses, and methods for saving power on a bus interface are described. A system includes a host, a device, and a repeater interposed between the host and the device. While the host and device are in a low-power state, the repeater monitors a first bus to determine if the device has woken up. When the repeater detects a remote wake-up event initiated by the device, the repeater generates an interrupt which is sent to the host. The host responds to the interrupt by initiating a resume wake-up event procedure that assumes the device is still asleep. In this way, the host is able to stay in the low-power state longer while also using a wake-up procedure that does not require the host to be aware of the existence of the repeater.