Research And Realization Of MicroCAN Bus Protocol Of Controllable Pitch Propeller Based On Embedded System

Controllable Pitch Propeller (CPP for short) is a high-tech and very important marine equipment. For meeting the informationization and networking requirements of marine power system, taking the embedded controller with field bus as the special controller of CPP control system has been a development trend. As one of the most important field bus, CAN bus has been widely used in marine power system. But from the point of view of Open System Interconnect Reference Model (OSI for short), CAN field bus low-level protocol defines physical layer (the first layer) and date link layer (the second layer), without including the application layer. At the same time, some standard CAN field bus high-level protocols are comparatively difficult to understand or develop; either suit for simply control network based on CAN bus such as CPP system.Based on the characteristic (such as short transmission distance, single control object and high reliability) of CPP control system, this thesis was working on applying a simple and reliable CAN application layer protocol: Micro CAN for short, which can be used as the CAN bus protocol of CPP control system, by analyzing and studying the application layer of CAN bus. Then the MicroCAN protocol would be put into actual use in CPP embedded controller.Firstly, we analyzed the structure and characteristic of CPP embedded control system, and put forward the actual requirement of CPP control field bus. Then according to the development and application of field bus technology, we analyzed and surmised the advantage of CAN bus applied in CPP control system.Secondly, we put forward the necessity of designing a special protocol according to the characteristic of CPP control system. Then we introduced goal of MicroCAN protocol, specially gave a detail of the identifier definition, master-slave structure, data transmission mechanism and programming of MicroCAN protocol, and carried it out by C++ language.Finally, we gave a brief discussion of the application of MicroCAN protocol in CPP control system, and viewed its development.Tested in the lab, MicroCAN protocol employed master-slave network model and no connection addressing sending process which simplified the data transmission. By adding the function of huge data transmission and setting the inquiry and resending of data transmission, it satisfying the reliability of huge data transmission. By simplifying the type definition of single frame transmission, it increased the effective data byte and improved the transmission efficiency. With all these advantages, MicroCAN protocol can be perfectly used as CAN bus protocol of CPP embedded control system.