Design And Implementation Of Train Announcement System Controller Based On HDLC Protocol

In the modern train control system, the Public Announcement System covering the whole train provides passengers with high-quality announcement public information broadcasting service, including the digital announcement, the transfer information and the special information, and so on. The Public Announcement System becomes one of the necessary parts of the modern train.The HDLC protocol is a classic data transmission protocol standard, and has been widely applied in the train communication system. With the development of the train technology, the application technical barriers of the HDLC bus make it necessary to realize the HDLC protocol by ourselves to improve the competitiveness of our country's railway train.This thesis introduces the design of the train broadcast system controller software supporting the HDLC communication protocol standard for the train control system based on the HDLC bus. Firstly, the technical characteristic of HDLC protocol is introduced. By analyzing the functional requirement of the Train Public Announcement System, the thesis chooses TMS320DM6446 (ARM+DSP) as the processor. The audio encoding and decoding algorithms are running in DSP. Based on embedded Linux operating system, the application process running in ARM, realizes the control of the HDLC device and gets the train control information through the HDLC communication with the Train Monitor System. The software is designed with modular components for operation of system information, process of train event, and functions of seven kinds of train-broadcastings, including the digital station broadcasting and cab-to-cab announcement. Finally, a lab testing environment has been built, and a comprehensive test has been given for the software functions.