USB Host Wake via Device Signal in Suspend Mode
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Solution Overview
Problem
In automotive systems, USB communication links face challenges in power management during suspend mode, where devices draw excessive current, violating specifications, and there is a need to wake up the host controller without maintaining the 5V VUSB supply, which is not feasible with standard USB interfaces.
Innovation Solution
The system multiplexes the TCU wake-up signal with one of the USB signal lines, allowing the network access device to transmit a wake-up signal to the telematics controller even when the VUSB power is shut off, reducing current drain and eliminating the need for additional wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the 5V VUSB supply is maintained in suspend mode to enable device wake-up, then the device can wake the host controller, but current drain increases beyond the specified 500uA limit
Solution Approach 1:
The patent extracts the wake-up signal transmission function from the power supply system. Instead of requiring continuous 5V power to enable wake-up, the system allows the VUSB power to be completely shut off while using a separate signaling mechanism (pull-up resistor configuration on data lines) to transmit wake-up signals. This separates the power delivery function from the signal transmission function.
Solution Approach 2:
The patent introduces an intermediary mechanism using the USB data lines and pull-up/down resistors as a mediator for wake-up signal transmission. The device can pull the data line to a specific voltage level through its internal resistors, creating a detectable signal on the dormant USB lines without requiring active power from the host. This intermediary approach allows communication without continuous power supply.
2Use of energy by moving object
If the USB host shuts down the power supply completely to reduce current drain, then current consumption decreases, but the device loses the ability to wake up the host
Solution Approach 1:
The patent enables the device to self-generate the wake-up signal using its own internal resources (pull-up resistors and data line configuration) without requiring external power assistance from the host. The device autonomously creates a detectable electrical signal on the data lines by configuring its internal resistors, allowing it to wake the host without drawing continuous power or requiring host-provided signaling capability.
Solution Approach 2:
The patent makes the USB data lines multi-functional by using them for both their standard data communication purpose and as a wake-up signal transmission medium. The same physical lines that carry data during active operation are repurposed to carry wake-up signals during suspend mode, eliminating the need for dedicated wake-up wiring or separate signaling mechanisms.
3Reliability
If an additional wake-up pin is added to the USB interface, then wake-up capability is enabled, but the device complexity and wiring requirements increase
Solution Approach 1:
The patent applies multi-functionality by making the existing USB data lines serve dual purposes: standard data communication during active mode and wake-up signal transmission during suspend mode. This eliminates the need for additional dedicated wake-up pins or wiring, maintaining interface simplicity while enabling wake-up functionality.
Data Source
AI summary
A system and method for communicating between a controller and a device is provided: The controller communicates with the device over a communication link. The controller shutting off a power supply that is connected to the communication link, for example, due to inactivity parameters. The device generating a wake up signal and transmitting the wake up signal from the device to the controller while the power supply is shut off.