Design Of MAV Digital Transmission Circuit Supporting MAVLink Communication Protocol

In recent years,with continuous innovation and progress in technology and reduction in manufacturing costs,the UAV market is also growi ng and developing.At the same time,the development also poses challenges.Flight control system for data collection speed,processing speed,accuracy has a more stringent requirements.The traditional MCU-based flight control system has a certain disadvantage on the speed of data acquisition system,data processing and data processing accuracy.However,the flight control system based on FPGA not only greatly shortens the development cycle,reduces the cost and ensures the high reliability of the system,but does not have the FPGA-based communication protocol.Therefore,it is of great significance to further research on the FPGA-based communication protocol.The MAVLink protocol has been used in a large number of flight control platforms and is suitable for mini UAV communications.Therefore,we choose the MAVLink communication protocol to do further research to realize the communication function of our self-developed flight control chip and ground station.According to the agreement of the open source code I summarize the realization of the agreement process,according to the function of the protocol I design MAVLink communication protocol circuit.The thesis mainly completed the following work:Through research and analysis of the protocol,16 MAVLink mes sages for flight control and ground station transmission are identified.According to the understanding of the protocol and design requirements,I design the overall structure of MAVLink communication protocol circuit.Data transmission uses UART serial port.In order to solve the problem of different transmission spped between the internal module the interface,I use asynchronous FIFOs to cache data and solve cross-clock domain problems.According to the function of the protocol,the entire circuit is divided into two parts,namely the decoding part and coding part.The decoding part mainly includes the core decoding circuit and the checking circuit.The part of the circuit realizes that decode the received data according to the frame format stipulated by the MAVLink protocol and send data through the UART.The coding part mainly comprises a message ID generating circuit,data controlling and reading circuit,a data length converting circuit,a message coding circuit,coding preprocessing circuit,message sequence generating circuit,common message encoding circuit,and heartbeat packet message encoding circuit.This part implements the data reading in accordance with the MAVLink protocol frame format for encoding.I use Modelsim to simulate the circuit of the design,after the simulation,I carry it out board level verification in the FPGA.Through the analysis of the simulation waveform and the data received by the serial port debugging software,It is verified that the data transmission circuit of the MAV supporting MAVLink communication protocol designed in this paper can encode and decode the data according to the protocol.