Design Of Four-Channel CAN Bus Module

CAN bus is widely used in automobile,marine,railway,mine exploration and many other fields because of its advantages of resisting disturbance,stability and reliability.With the improvement of system complexity,multi-channel CAN bus architecture is adopted to improve the real-time performance of communication.Meanwhile,it allows users to design redundancy protocol to improve the security of the system.Aiming at CAN bus communication requirement of a marine monitoring system,this thesis designs a four-channel CAN bus communication module with high integration,good maintainability and strong compatibility in hardware and software.Firstly,this thesis discusses hardware and software design of the four-channel CAN bus module.Referring to M-Module standard,the hardware design is based on a FPGA chip and four isolated CAN transceivers are used to achieve four-channel CAN communication electrical isolation.The module uses four IP cores to implement CAN control logic.Based on the research of M-Module read/write specification and interface protocol of the CAN bus IP core,interface conversion logic is designed with VerilogHDL,which realizes the communication between the designed module and the embedded system controller.The software for the embedded controller is operated in the embedded Linux.It is designed to realize software buffering of multi-channel CAN bus data by taking circular queues.Considering the communication needs of the module and hierarchical software development idea,this thesis designs highly packaged software interfaces of the module for users,which provides a strongly portable function library.Aiming at the reliability requirement of the module in the marine monitoring system,this thesis researches the test method and specification of CAN bus nodes.A layered test scheme is adopted to verify the correctness and rationality of the hardware and software design.The module is tested by physical layer,data link layer and application layer.This thesis uses a communication card to build test system for the module,and a test software is designed.The experimental results show that the four-channel CAN bus module can realize the communication of CAN bus data and features in reliability and stability,which meets the design requirements.