Research And Implementation Of AS 5643 Multichannel Bus Interface Digitization

As the I/O interface of flight management and control computer,multichannel interface is used to realize the functions of bus information synthesis,resource sharing,task coordination and fault-tolerant reconfiguration.Flight control related hardware is usually customized,and the update iteration is slow,which results in the corresponding software development speed being limited by hardware.The digital model of hardware is to use software to simulate hardware and realize hardware virtualization.It can solve the above problems.Therefore,in this thesis,the digitization of multichannel interface based on AS5643 protocol is taken as the research subject,and the digitization of multichannel interface of flight management and control computer is realized,so as to achieve the consistency between the results of loading real flight control code on digital model and real hardware.The main contents of this thesis are as follows:1.Analyzing the functional requirements of the multichannel interface,the specific index of the model and the overall digital design scheme are put forward.The communication mode of the digital model of the multichannel interface is selected,and the initialization and operation process of the digital model of the whole multichannel interface are designed.2.The functions of AS 5643 physical layer,link layer,protocol processing unit,bus management layer and host interface are analyzed.A function-based digital scheme is proposed to realize data packet verification/search,configuration information management and interface functions.3.The synchronization mechanism of high-low handshake is analysed based on hardware.On the basis of the original transmission cycle of time difference after synchronization,it is optimized according to the characteristics of software delay determination,tight synchronization is realized,and the problem of synchronization waiting time-out caused by too long transmission delay of synchronization signal is solved.4.Aiming at the improvement of sending and receiving strategy of asynchronous stream packets in AS 5643,based on the analysis of the advantages and disadvantages of time triggering and event triggering,in this thesis,to use event triggering as a supplement to time triggering is proposed to solve the problem that asynchronous stream packets can not be retransmitted over time;to organize data packets by time offset instead of message ID to improve the running speed of the model.5.Analysing the advantages and disadvantages of the current mainstream digital simulation software,Simics is selected and its mechanism and characteristics are analyzed,a digital model of multichannel interface is built,and the digital model is verified that meets the requirements in overall simulation speed,frame cycle and synchronization accuracy through testing.In this thesis,through the design and implementation of the digital model of multichannel interface,the development of software and hardware is synchronized by using the digital model to solve the problem of the lag of flight control software development due to the complexity of hardware design and the long development cycle of multichannel interface.