Broadband Router Embedded Operating Systems Design And Implementation

The embedded software is the soul of embedded system, and the embedded OS is the kernel of the embedded software. So the key of embedded system's development is the development of embedded software, especially the embedded OS. Compared with the traditional operating system, the embedded OS has some specifications, such as real time, high efficiency, hardware dependency, fixed software, etc. And to be based on Internet and special application is the trade of the embedded OS' development.There are two ways to implement the embedded OS. First, get the system based on modification of some mature system. Second, get the system by yourself. The first way requires lower cost and less time to implement. But when in some special application, it still needs large mount of work to modify and to strip the original system. The second way requires large mount of work too. But the system is designed targeting the dedicated application, and therefore fits the application very well. Broad band router is such an application.Broad band router is a typical embedded product that has been widely used. It supports Internet's connection sharing and provides some functions as a router. Compared with a normal PC, The device has some outstanding virtues, such as higher stability, lower cost, smaller and lighter, etc. Especially, it does not need professional knowledge to manage. As an embedded product, Broad band router has some specifications, such as real time, be busy in handling network packets, simple structure, etc. And the focus of implement of the Broad band router's software is the embedded OS.Targeting the broad band router, an embedded OS and NAT are implemented by the second way in the thesis. The thesis describes the design of the embedded OS and the implement of every part of the embedded OS including task management, memory management, the interface to hardware and so on. The design and implement of NAT is described in detail too. Finally, tests and evaluation are made between the system and Linux. The results show that the system has good efficiency as Linux has, and a little more efficient than Linux in some extents. Although the system runs well, but there are still lots of work to do to improve the system and make it more mature.