Study On Network Protocol Of AFDX And Realization Based On FPGA

With the rapid development of avionics system, electronic equipment of airplanes tends to diversification and complication. The traditional communication network with low speed and large amount of electric cable, cannot satisfy the modern avionics'requirements, thus it restricts the update of avionic device. As a result, optimizing the air communication and improving the avionic device by applying new-type communication network become the essential task in the research and development of new generation large aircraft. The main purpose of this paper is the application of Avionics Full Duplex Switched Ethernet Network (AFDX) in the C919.First, on the basis of research background and significance, defects of low-speed traditional communication bus as well as commercial Ethernet's instantaneity and certainty are discussed. The necessity of introducing AFDX as new generation avionics data is demonstrated.Second, according to the function and performance index of the system and the present physical condition, the frame of hardware and software to realize AFDX terminal system are designed. The hardware structure are divided into physical layer realizing circuit, top layer protocol realizing circuit and power circuit, based on the physical structure of AFDX terminal system. Software is divided into AFDX port realization, MAC layer realization, redundancy management, integrity detection, virtual link module and UDP, IP packing module, according to the physical layer, data link layer, network layer, transport layer and application layer in AFDX protocol. Besides to AFDX port, the other 5 parts are realized with FPGA.Third, according to the relationship between AFDX and Ethernet, network calculus, which is used in analyze the delay of Ethernet, is adopted in AFDX network to calculate end-to-end system delay of AFDX in worst-case condition to analyze the performance of AFDX network.Last, manufacturing of original prototype of AFDX terminal system are completed. Through AFDX network analyzer, terminal system's data are received; communication function realization and system state analysis results are displayed schematically. Besides, end-to-end system delay of AFDX is figured out via examples to test and verify the reliability of AFDX. Reliability of AFDX and its advantages are testified by comparing the calculated results with avionics standards and simulation.