Low-Power CAN Management with Selective Wake-Up
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Solution Overview
Problem
Controller Area Network (CAN) systems face high power consumption when communicating over multiple buses, which is unacceptable in low-power applications like automotive systems, despite the need to quickly filter and react to relevant messages.
Innovation Solution
A system with N CAN listeners and M CAN controllers, where at least one CAN controller is in an always-on power domain, and a microcontroller in a second power domain that can be powered up to analyze and filter messages, using a power controller to manage the activity state of CAN controllers and transceivers, optimizing power usage through selective wake-up and priority policies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If N data paths are used to communicate over N CAN buses, then message handling capability is improved, but power consumption increases
Solution Approach 1:
The system segments the CAN communication functionality into N separate CAN listeners, each capable of independently monitoring a specific CAN bus. This segmentation allows the system to distribute the monitoring load across multiple low-power listener units rather than requiring N full-featured data paths, thereby maintaining message handling capability while significantly reducing overall power consumption.
Solution Approach 2:
The system dynamically activates only the necessary components based on real-time requirements. When a CAN message needs to be processed, the system wakes up the specific CAN listener and associated CAN controller for that bus, processes the message, and then returns to sleep mode. This dynamic on-demand activation ensures that power is consumed only when necessary, resolving the contradiction between continuous message handling capability and low power consumption.
2Use of energy by moving object
If the system enters deep hibernation to reduce power consumption, then power usage is improved, but message response time deteriorates
Solution Approach 1:
The CAN listeners are kept in a preliminary active state during hibernation, continuously monitoring the CAN bus for activity. This preliminary monitoring action allows the system to detect incoming messages immediately even while in deep hibernation, triggering a wake-up event without delay. Thus, the system maintains both low power consumption during hibernation and fast response time to relevant messages.
3Productivity
If multiple CAN controllers are always active to handle multiple buses, then message filtering capability is improved, but power consumption increases
Solution Approach 1:
Instead of keeping multiple CAN controllers continuously active, the system employs periodic activation of CAN controllers based on detected bus activity. When a CAN listener detects activity on its monitored bus, it triggers the associated CAN controller to wake up and perform message filtering. After processing, the controller returns to sleep mode. This periodic action pattern maintains effective message filtering capability while minimizing power consumption by ensuring controllers are active only when necessary.
Data Source
AI summary
The invention relates to a system and a corresponding method for communicating over N CAN buses comprising comprising N CAN listeners, wherein each of the CAN listeners is configured to be coupled to a respective CAN bus and to detect CAN activity on the CAN bus to which it is coupled; M CAN controllers, wherein 1≦M<N; and a power controller, wherein each CAN listener is configured to generate a control signal in response to detecting CAN activity on the CAN bus to which it is coupled and send the control signal to the power controller which controls the activity state of at least one of the CAN controllers.