Variable Oscillator for CAN Bit Time Adaptation
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Solution Overview
Problem
Existing CAN systems face challenges in adapting to various bit times and oscillator precision requirements, particularly in CAN controllers, where precise oscillator frequencies are necessary but often not achievable with standard components, leading to limitations in data communication and system reliability.
Innovation Solution
A CAN module with a microprocessor and a variable oscillator that generates different frequencies, using a reference frequency derived from CAN bus messages or a crystal oscillator, allowing automatic adjustment to system bit rates and oscillator precision, enabling precise communication and error detection according to CAN protocol rules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed frequency oscillator is used in a CAN controller, then the oscillator provides stable clocking, but the CAN controller cannot adapt to different bit times and communication rates
Solution Approach 1:
The patent implements a variable oscillator that can dynamically change its frequency based on the required CAN bit time. The oscillator frequency is controlled by a control voltage that can be adjusted to generate different frequencies, allowing the CAN controller to adapt to various communication rates and bit times while maintaining stable clocking for each selected frequency.
2Adaptability or versatility
If a variable frequency oscillator is used to adapt to different bit times, then the CAN controller can communicate at various rates, but the oscillator precision required by CAN protocol becomes difficult to achieve
Solution Approach 1:
The patent incorporates a feedback mechanism where the actual oscillator frequency is measured and compared against the target frequency. The measurement unit determines the actual bit time based on oscillator pulses, and this information is used to generate a control signal that adjusts the oscillator frequency, creating a closed-loop system that achieves the required precision despite the variable frequency capability.
3Reliability
If precise oscillator frequencies are required for CAN communication, then communication reliability is improved, but standard oscillator components cannot provide the necessary precision
Solution Approach 1:
The patent introduces a frequency control mechanism that acts as an intermediary between the standard oscillator component and the CAN controller. This control system measures the actual oscillator frequency and adjusts it through feedback control, allowing standard, easily manufactured oscillator components to achieve the precise frequencies required for reliable CAN communication.
4Device complexity
If the oscillator frequency is fixed at a specific value, then the oscillator design is simplified, but the CAN controller cannot communicate with systems using different bit rates
Solution Approach 1:
The patent designs the oscillator system to be universal, capable of operating at multiple frequencies to support different CAN bit rates and communication standards. The oscillator receives a control voltage that can be adjusted to generate various frequencies, making the same hardware design adaptable to different communication requirements without needing separate oscillators for each bit rate.
Data Source
AI summary
A device suitable for use as a module in a Controller Area Network (CAN) system with a bus or connection includes relatively simple and inexpensive components, including an oscillator that generates a number of different frequencies in response to directions from a microcomputer. A CAN Controller receiving the frequencies is connected to the bus via a transceiver. The device has utility for verification and validation work in association with a CAN system.