Design And Implementation Of Multimedia And Network Controller Based On Embedded Linux

Embedded product has already been used in different areas of the world extensively going with the development of digital information and network technology. It is an inevitable choice to adopt embedded operating system due to the complex and powerful functions of embedded system. Among the mainstream embedded OS, embedded Linux attracts more and more attention because of its free, high reliability, portability, open source and powerful network functions. In this paper, an embedded multimedia network controller is presented based on embedded Linux with a core of AT91RM9200 microprocessor.The dissertation firstly proposes a plan of selecting processor and embedded OS based on demand. Comparing with other embedded product, 32bits processor AT91RM9200 based on embedded Linux is selected as the key control unit. An external board is designed with multimedia interface including audio, LCD display and network interface such as Ethernet, CAN integrated on ARM minimum system, and a HMI expansion board is designed with MCS51 and CPLD, to receive and display elevator callings signals. All the parts together construct a modularized, easy-expanding hardware platform of embedded system.Secondly, building of embedded Linux software development environment is illustrated in detail, consisting of the implementation to cross-platform development toolchain, building of development environment based on Linux server, obtaining of a functional root file system, and building of RAMDISK and JFFS2 file system. The dissertation proposes detailed implementation ways and key steps for the questions mentioned in this chapter.In essence, Linux device driver is a shared library of hardware service program in Linux kernel, which is very important in Linux architecture. The dissertation discusses basic principles of Linux device driver, analyses memory management, interrupt handling and other key issues in driver development, and take hardware devices for example, such as audio, serial device, to illustrate driver realization methods. It provides a basis for the application layer software development.Finally, a multimedia network main controller and a HMI controller is applied in elevator car control system based on the accomplishment of hardware and driver software design. It can not only receive and display elevator calling signals, but also fulfill the functions of LCD display, voice stations and other intelligent services, which are tested in the laboratory environment. Overall, this system has some practical value, and simultaneously provides a referential experience to other embedded-Linux controllers in industrial control field.