Embedded System Application And Development Of Audio On Demand

This thesis focuses on the application of embedded system on personal audio-on-demand system. Mainly used in such occasions as coaches and cafes, the audio-on-demand system provides individualized MP3 on demand service, which has great practical value and market prospect. Since the Client/Server mode consisted of normal PCs cannot be used in this system, the computer system must be customized according to special demands. This is exactly the feature of embedded system so that embedded system technique is used a lot in the designing and developing of this audio-on-demand system. The embedded system used in this audio-on-demand system is demonstrated in two major application fields: first, the designing of the server; second, the development of Ethernet conversion board. Server's main board is an embedded main-board, while the Operation System is Linux. According to the need of the system and in view of the Ethernet technology used in this system, Linux is customized. The Linux kernel is expanded to develop the most suitable device driver which can transmit and receive data packets. This device driver is loaded into the kernel when needed. It provides the standard interface for the application program. And the server program is based on the device driver so that the playing term can download mp3 files form the server. Therefore, the designing of the server consists of two parts: first, the device driver which can transmit and receive data packets; second, the server main program. This thesis is just focusing on these two aspects with the device driver as the emphasis. Data conversion board is a complete computer system with the am!86 of AMD as CPU, DP83902A of NS as the NIC, and the RAM, PROM and external interface logic. The software of this board is written with X86 masm. The hardware and the software together are the complete embedded system. Its function is to convert data between Ethernet and serial ports, analyze data packets from Ethernet and transmit them to serial ports; at the same time, it transmits the data from serial ports to server through Ethernet. Completed on the basis of designing and development, this thesis aims at introducing the designing ideas and the developing course while elaborates some relevant technical background information.