Abstract: In order to solve the problem of communication mismatch between autopilot system using CAN (Controller Area Network)bus and navigation equipment using serial port communication, a communication conversion interface module based on Cortex-M3 is designed and the function of data conversion between serial port and CAN bus is realized. Aiming at the problems of poor signal stability and low baud rate accuracy of traditional CAN transceiver circuit CTM1050, an alternative hardware scheme is proposed and implemented to improve the timeliness and stability of data communication. Based on the CAN2. 0B extension frame, the internal CAN bus protocol of the autopilot system is designed to ensure the scalability and stability of the bus. The protocol can assign identity frames according to the priority of message information to ensure the orderly transmission of bus data. The actual test results indicate that the communication module is normal and the communication effect is good. The communication module has a certain universality and can be used in a variety of equipment systems. 

Key words:  , Cortex-M3 microcontroller unit, controller area network(CAN), serial port, autopilot system, identifier