Serial Wake-Up Module for Selective Subscriber Station Activation
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Solution Overview
Problem
Existing bus systems face challenges in selectively waking up subscriber stations efficiently at high bit rates, particularly when using CAN XL frames, which lose compatibility with Classical CAN and CAN FD, and require expensive precise clocking and higher protocol complexity.
Innovation Solution
A transmitting/receiving device with a wake-up module that serially evaluates digital reception signals to identify wake-up frames, allowing selective wake-up of subscriber stations independently of bit rates, without needing to decode short bits of the CAN XL data phase individually, and using a clock source with high tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If CAN XL frames are used for communication at bit rates above 8 Mbit/s, then transmission speed is improved, but compatibility with Classical CAN and CAN FD is lost and device complexity increases
Solution Approach 1:
The patent segments the wake-up signal transmission into two distinct phases: an arbitration phase using Classical CAN format for compatibility and wake-up signal transmission, and a data phase using CAN XL format for high-speed data communication. This segmentation allows the system to maintain compatibility with Classical CAN and CAN FD while enabling high bit rate communication when needed.
Solution Approach 2:
The system dynamically switches between Classical CAN and CAN XL protocols based on operational requirements. During wake-up sequences, Classical CAN is used for broad compatibility, while CAN XL is activated for high-speed data transmission. This dynamic protocol selection resolves the contradiction between speed and compatibility.
2Measurement precision
If CAN XL transceivers with precise clocking are used for high bit rates, then transmission accuracy is improved, but cost increases
Solution Approach 1:
The patent applies partial precision by using Classical CAN's tolerant clocking for the wake-up phase where high precision is not critical, and reserves CAN XL's precise clocking only for the data phase when high-speed accurate transmission is required. This partial application of precision reduces overall system cost while maintaining necessary accuracy.
Solution Approach 2:
The system changes the clock tolerance parameter dynamically: using high tolerance clock sources for Classical CAN wake-up signals and switching to precise clocking only when CAN XL high-speed transmission is activated. This parameter change allows cost-effective implementation by avoiding continuous use of expensive precise clocking.
3Device complexity
If Classical CAN frames are used for selective wake-up, then device complexity is reduced, but bit rates above 8 Mbit/s cannot be achieved
Solution Approach 1:
The communication protocol is segmented into two parts: wake-up signal transmission using simple Classical CAN frames, and data transmission using CAN XL for high bit rates. This segmentation allows the system to use low-complexity Classical CAN for wake-up while achieving high speeds during data transmission.
Solution Approach 2:
The system performs preliminary wake-up using Classical CAN frames before activating high-speed CAN XL communication. This preliminary action using simple protocols prepares the system for subsequent high-speed operation, allowing bit rates above 8 Mbit/s to be achieved without requiring the high-speed protocol to be active continuously.
Data Source
AI summary
A transmitting/receiving device for selectively waking up a subscriber station of a serial bus system. The transmitting/receiving device has: a transmitting module for transmitting a transmission signal, which is created for communication in the bus system based on a frame, as an analog signal to a bus; a receiving module for receiving an analog signal from the bus and for generating a digital reception signal from the analog signal received from the bus; and a wake-up module for waking up the subscriber station after the subscriber station has been put to sleep to save energy, wherein the wake-up module is designed to serially carry out at least two different evaluations in order to decide whether or not the digital reception signal corresponds to a wake-up frame which gives instructions to activate the transmitting module to wake up the subscriber station.