CAN Transceiver Wake-Up Unit for Selective Node Activation
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Solution Overview
Problem
Existing CAN transceiver technologies lack an efficient method to selectively wake up CAN controllers or microcontrollers from a sleep state without interfering with the CAN bus communication, particularly in scenarios where only specific nodes need to be activated.
Innovation Solution
The proposed CAN transceiver incorporates a wake-up unit that detects silent sections in the CAN bus signal, specifically identifying wake-up pulses with differential bus voltages below a predefined negative threshold. This allows the transceiver to send a wake-up signal only in response to detected wake-up pulses, enabling selective activation of CAN devices without disrupting ongoing communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CAN transceiver continuously monitors the CAN bus to detect wake-up pulses, then wake-up functionality is enabled, but power consumption increases during sleep state
Solution Approach 1:
The monitoring function is segmented into two parts: a low-power wake-up unit that only monitors for wake-up pulses during sleep state, and a full-function receiver unit that operates only when activated. This segmentation allows the system to maintain wake-up detection capability while minimizing power consumption by keeping most components dormant during sleep.
Solution Approach 2:
The wake-up unit acts as an intermediary between the CAN bus and the main receiver unit. It selectively detects wake-up pulses and triggers activation of the full receiver unit only when necessary, thereby enabling reliable wake-up detection while preventing continuous operation of power-consuming components.
2Speed
If the transceiver activates upon detecting any signal change, then communication responsiveness is improved, but false wake-ups from normal CAN communication occur
Solution Approach 1:
The wake-up unit is designed with specialized detection characteristics that differ from the general receiver unit. It uses specific voltage threshold criteria (detecting differential voltages more negative than a predefined threshold) that are tailored to recognize genuine wake-up pulses while ignoring normal CAN communication signals, thus achieving both fast response and high selectivity.
Solution Approach 2:
The system changes the detection parameters specifically for wake-up pulse detection. The wake-up unit monitors for differential voltages that are more negative than a predefined threshold, which is a distinct parameter setting from normal CAN signal reception. This parameter differentiation allows the system to respond quickly to valid wake-up signals while filtering out normal communication traffic.
3Reliability
If the transceiver remains in active state to ensure immediate communication, then communication reliability is maintained, but energy consumption increases
Solution Approach 1:
The transceiver dynamically changes its operational state based on communication needs. The wake-up unit operates continuously in a low-power mode during sleep state, maintaining minimal monitoring capability. Upon detecting a wake-up pulse, the system transitions to a fully active state with the receiver unit operational, ensuring communication reliability only when necessary and minimizing energy loss during idle periods.
Data Source
AI summary
The present invention relates to a Controller Area Network, CAN, transceiver, comprising: a transmit data, TXD, interface, a receive data, RXD, interface, a bus interface for coupling to a CAN bus, a receiver unit, a transmitter unit, and a wake-up unit, wherein the bus interface is configured to receive a first differential voltage signal, referred to as the bus signal, from the CAN bus via the bus interface, wherein the wake-up unit is configured to detect a silent section of the bus signal representing an end-of-frame, EOF, field of a first CAN frame and/or an inter-mission-space, ITM, following to the EOF field based on the bus signal, wherein the wake-up unit is configured to detect in the silent section of the bus signal at least one wake-up pulse having a differential bus voltage that is less than a first predefined negative threshold voltage (TH1), and wherein the wake-up unit is configured to cause a wake-up signal representing a wake-up instruction to be sent via an interface of the transceiver, in particular the RXD interface or another interface of the transceiver, in response to the at least one detected wake-up pulse. The present invention also relates to a CAN device, a CAN system and a method for the CAN transceiver.