Design And Implementation Of Embedded Bus-Mounted System

The intelligent public transportation system has been brought up because of the traffic jam problem. The bus-mounted system as its important part will play a more important role in the intelligent public traffic system. The embedded bus-mounted system based on ARM processor is designed and implemented in this dissertation. It is integrated with a lot of advanced technical achievements based on communication technology, computer technology and GPS location technology.The bus-mounted system is the data acquisition source and the receiving unit of scheduling orders of the intelligent public transportation system, which is also the operation base of the intelligent public transportation system.The main functions of the bus-mounted system consists of vehicle positioning, overspeed monitoring, driving line detection, emergency alarming, automatic station-reporting, artificial station-reporting and communication with information center, etc.Based on the system requirements of the bus-mounted system, the integral structure of the bus-mounted system is designed in detail considering the modular design methodology and the expansibility. Meanwhile, the theory and application of GPS and GPRS technology are analyzed carefully.At first, the embedded development environment of the bus-mounted system is built, including the port of the bootloader, the building of the cross-compiling environment, the improvement of the underlying device driver and the port of the embedded Linux. And then the application software of the system is designed based on the above in detail. The system makes full use of multi-tasks processing mode which combines the multi-process and multi-thread technologies. All events and commands are solved by unified message handling mechanism. In other words, each receiving command and message event is packed as the system task and loaded into the task processing queue. Then they are distributed in sequence based on their priorities by the distribution processing function of the system task. In order to meet the demand of information commucation between the bus-mounted system and the information center, the communication protocols is also designed and implemented in this thesis.