Study On An Embedded Multiplex VOD System Based On Niosâ…¡

With the fast development of transistors technology, the design of the embedded system is advancing towards System on a Chip. The System on a Programmable Chip based on FPGA attracts designers' attention recently by its characteristics, such as flexibility, programmable software and hardware, etc. But the study and the application in this field are less in China, so the research on it is very important.This paper introduced a scheme of implementation of the embedded multiplex Video on Demand (VOD) system based on Nios II. We use Nios II as the main controller of the system, storage large amounts of video data in the hard disk and solve the problem of DMA controlling with hardware method. We extend external video decoder and module of character on screen, which satisfy 32 channels MPEG-1 programs' real time broadcasting. We use SOPC Builder and Quartus II development tools and integrate Nios II CPU and configurable custom logic in the FPGA, which satisfy the requirement of multiplex real-time playing. This design method makes the circuit structure sample, improves the processing speed and makes the system practicable.Firstly, we discuss the application and development trend of the embedded system and the specification and current status of SOPC. Furthermore, we introduce the structure and characteristic of Nios II processor, Avalon bus and interrupt theory. A concrete example of VOD system is given. We introduce the whole procedure of software/hardware design about the VOD system and emphasize on the idea and realization of Nios II custom configurable logic and HAL software development. In the article, we introduce each module of DMA controller custom logic including the interface and the state machine. Then we introduce the ping-pong operation of RAM and the shift output logic. At last, we introduce the realization of HAL interruption and FAT32 file system.