USB Wakeup Signal Generation on Non-Powered Bus Lines
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Solution Overview
Problem
Current USB standards do not effectively manage the waking up of a USB bus from a non-powered state, leading to inefficiencies in power management and system responsiveness.
Innovation Solution
A method and module system that detects a wakeup condition to generate a wakeup signal on a power line or a single-wire sideband, allowing the USB bus to be powered up by a host module, enabling the USB bus to transition from a non-powered state to an active or suspended state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the USB bus remains in a non-powered state to save energy, then power consumption is reduced, but the system responsiveness and ability to detect wakeup conditions deteriorates
Solution Approach 1:
The USB bus system is segmented into powered and non-powered states, with specific subsystems (wakeup generation module, wakeup detection module) remaining active even when the main bus is powered down. This segmentation allows the system to maintain minimal responsiveness while achieving significant power savings.
Solution Approach 2:
A wakeup signal acts as an intermediary mechanism that bridges the gap between the non-powered state and the active state. The wakeup generation module and wakeup detection module serve as intermediaries that enable the transition from power-saving mode to active mode without requiring continuous full bus power.
2Reliability
If the USB bus is continuously powered to ensure immediate responsiveness, then system responsiveness is improved, but power consumption increases
Solution Approach 1:
Instead of continuous powering, the system employs periodic or on-demand power delivery. The host controller powers up the USB bus only when a wakeup condition is detected, creating a periodic activation pattern rather than continuous operation, thereby reducing overall power consumption while maintaining responsiveness.
Solution Approach 2:
The USB device autonomously detects wakeup conditions and generates wakeup signals without requiring continuous host monitoring. The device serves itself by detecting its own wakeup conditions and initiating the power-up sequence, eliminating the need for continuous host-side power delivery.
3Loss of energy
If power is delivered only after wakeup detection to save energy, then power efficiency is improved, but the time to activate the USB bus increases
Solution Approach 1:
The host controller is pre-configured with the capability to rapidly power up the USB bus upon receiving a wakeup signal. The power delivery path is prepared in advance, allowing the bus to transition quickly from non-powered to powered state once the wakeup condition is detected, minimizing activation time while maintaining power efficiency.
Data Source
AI summary
Universal serial bus wakeup when the bus is not powered. In one embodiment, a method of waking up a universal serial bus (USB) from a non-powered state, comprises: upon detection of a wakeup condition, a wakeup generation module associated with a USB device generating a wakeup signal on a power line of a USB bus coupled to the USB device, or on a single-wire sideband; and a host wakeup module detecting the wakeup signal and causing the USB bus that is coupled to the USB device to be supplied with power.