Research And Application Of Embeded Linux On DM6446 Platform

Embeded system which centers on practical application, takes computer technique as its theory basis, software and hardware can be customized as required, and is restricted by function provided and cost of R&D. Due to flexibility of hardware and software design, embedded sytem differs greatly from traditional PC system. During embeded system design, we generally customize and modify software according to hardware environment.The subject researched by the thesis is an optical network ethernet switch system with voip operation. In order to realize the system function, the thesis proposes the software and hardware design method, and has accomplished the system design goal.First, the thesis introduces the hardware function which is implemented by system platform; proposes the modularized hardware design scheme. Then implements the parts selection, and implements the detailed designment of every important module and interface. The function of every part of the hardware design scheme is definite, and this is not only very clear during design process, but also is beneficial to resolve problems. The work of hardware design has close relationship with device driver design, so convience of driver design should be considered during hardware design process.After finishing the hardware work, in order to facilitate the system code upgrade and debug, the thesis debugs and ports the bootloader code by using the hardware emulator, and realizes the basic boot environment for the system board. Under the boot environment, the thesis realizes serial port, network controller, DDR2 controller, NOR Flash etc device driver. So all the hardware can be normally used under the boot environment, and facilitates the download, debug and upgrade system code. In order to do better product upgrade work, the thesis realizes custom program for system upgrading. In order to faciliatetes the upper layer protocol, switch management and remote web management etc function, the thesis achieves to port the 2.6.18 version Linux kernel on system hardware platform under the boot environment. According to all kinds of devices on the specific electronic board, the thesis realizes the device driver under linux for emac device, ethernet switch, e2prom, spi controller, led, keystroke isr, le88221, asp audio interface and mdio interface etc device driver, and provides platform independent interface to upper level layer application software. According to the feature of flash storage device, the thesis makes jffs2 filesystem. In order to make full use of the capacity of flash device, the thesis debugs and realizes the flash device partition. The paper also ajusts the Linux kernel configuration for usb device support to use usb device normally on system platform.The subject researched by the thesis has already been applied in the actual product successfully, and been strictly tested. The work of the research subject is the necessary and most difficult work during initial stage of embedded system development. Study of the typical application of Linux building process on embeded device has great practical and guiding meaning for embeded operating system research and application, device driver write.