Platform Construction And Performance Research Of Flexray Bus

With the development of modern automotive technology, Vehicle safety performance has become increasingly demanding. At the same time, the number of the electronic control unit and sensors has increased significantly, in particular, the increase in automotive by-wire system (the X-by-Wire), which also promote the development of the car bus and network technology. Traditional vehicle bus networks such as CAN, LIN etc, for some of their own inherent characteristics, in some applications, they has been unable to meet the current need for the data exchange of vehicle safety performance and a wealth of information inside and outside of the vehicle. Therefore, the new-vehicle network bus called FlexRay comes into being. FlexRay protocol is developed by the FlexRay Consortium, and is developed jointly by the BWM and DaimlerChrysler originally to meet their current and future demand for their products. Then there are Bosch, NXP, Freescale, GM, Volkswagen and other companies to join to improve the FlexRay protocol constantly, and in2005, released the V2.1version of the FlexRay protocol. FlexRay protocol is based on BWM Company Byte Flight protocol and extended, has been supported by many automobile manufacturers at the time of launched. The FlexRay V1.1has been successfully applied to the2006car of the BMW X5,and the FlexRay V2.1version in2009in the BWM X6drive-by-Wire.This paper carried out a detailed study of the FlexRay protocol, a detailed analysis of the relevant characteristics of the FlexRay protocol (message frame format, wake-up, startup, media access control, time synchronization, etc.), physical signals, the network topology and protocol operation control content. On this basis, FlexRay controller and transceiver products currently support the FlexRay protocol of the major semiconductor manufacturers are listed and analysis in detail. Finally this paper adopted the higher price performance ratio, easy to purchasing, and the Freescale MC9S12XF512MCU, which integrated FlexRay Protocol Controller. The FlexRay bus driver used the NXP TJA1080, which also a mature product in industry. Using these components, this paper builds the FlexRay bus test platform for the relevant performance test. In aspects of FlexRay protocol code written&configuration, this paper uses a new way to improve the efficiency of the FlexRay bus design in-vehicle communications network and reduce the difficulty of coding by using Network Designer::FlexRay software.Using the platform build and PC monitoring software programmed by Freescale FreeMASTER, in-depth study on the networking of the FlexRay bus network, bus bandwidth utilization and message scheduling is executed.This paper proposed a estimation method of the utilization of a FlexRay bus, and researched message scheduling algorithm for optimal FlexRay bus static segment and dynamic segment. Finally, actual test is made on the FlexRay bus protocol features and reliability of communications redundancy and the results were analyzed, in the actual construction of platform.