Design And Testing Of MAVLink Protocol Circuit In Multirotor Unmanned Vehicles Autopilot Chip

The civil UAV is developed rapidly as the advance of technology and reduction of cost. As for multi-rotor, however, control systems based on MCU are still commonly used around the world,these kinds of multi-rotor UAV has a disadvantage of speed for data acquisition and processing. Therefore, we used FPGA for designing autopilot system, which can get reduced costs, improved accuracy and fast speed of operation. Moreover, due to these characteristics such as the high r eliability of FPGA, shorter design cycles, design flow from top to bottom, overall performance will be greatly improved.To communicate multirotor unmanned vehicles autopilot chip with Mission Planner supported MAVLink protocol, we researched the MAVLink p rotocol and designed MAVLink protocol circuit.This thesis mainly finishes the following works:To send information collected by multirotor unmanned vehicles autopilot chip to Mission Planner, we analyzed the MAVLink protocol and determined 10 pieces of MAVLink message used for sensor data transmission. Furthermore, a new message used for realtime control of UAV was added thus the general structure of MAVLink protocol circuit was proposed.To adapt to wireless data transmission with different transmission s peed, we used UART interface. Based on the principle of phase accumulator, The UART interface can transmit data at any baud rate. And to overcome the mismatching between data transmission of MAVLink and interface speed, we desig ned buffering circuits based on asynchronous FIFO thus transmission efficiency can be significantly increased.The MAVLink protocol circuit is mainly composed of five sub-circuits: the msgid generation circuit, data receiving and storing circuit, MAVLink data buffer circuit, MAVLink encoding circuit and control data receiving circuit. These circuits enable data receiving, valid information extraction, data sorting, verification, coding and decoding.Using Modelsim, this thesis stimulates the function of MAVLink communication protocol circuit and its sub-circuits. Then, the MAVLink communication protocol was tested and verified in FPGA development board. By analyzing stimulation waveforms, data from serial debugging software, and data from Mission Planner, the MAVLink communication protocol circuit is confirmed to be capable of transmitting sensor data, receiving and decoding the control data message encoded MAVLink protocol.