Design Of UC/OS-II For A CAN/LIN Gateway In Automative Mixing Body Network

With the development of automotive electronic, the distributed body control systems get control instead of the centralized system step by step. CAN (Control Area Network),which has superiority in dependability,unabroken arbitrage and multi-host etc, becomes the best choice in the body control network. Due to the higher cost CAN, in the situation where we do not need the high speed transmission, LIN( Local Interconnect Network) can provide the solution instead. As a result of CAN,LIN synchronously existing, the idea of virtual CAN node is used on the Gateway of CAN/LIN to get the consentaneous communication.To meet the need of strictly real time required by automotive body control systems, a design of CAN/LIN Gateway based on real-time system is put forward, and the particular hardware & software implementation of the gateway is given in the article. We make use of virtual CAN node to interconnect two kinds of network. Also in the system, we build the message buffer queue structure in order to reduce the message loss rate caused by protocol conversion due to the special role the Gateway represented in the network.Embeded real time computing is being used in many safety-critical systems (SCS),such as medical devices, aircraft flight control, weapons, nuclear systems, and transportation control.Because safety-critical systems are those systems whose failure could result in loss of life, significant property damage, or damage to the environment, people have to pay special attention to such systems.In safety-critical systems, real-time operating system is the unique system software which abut upon hardware. As a result, its dependability is much concerned to the whole computing system. We bat around the transplantation of real-time system uC/OS-II. A window-constraint technique is adopted to investigate the violation of task's deadline over a finite time range while task is consecutively invocated , which is used to define the criticality of real-time task. As a result, a real- time scheduling algorithm based on improved shortest urgent distance first (ESUDF) is proposed. The algorithm can efficiently support the mixed criticality tasks to run on the same computer. At the same time , the high criticality real-time task is preferentially executed in case of instantaneous overload of tasks.To solve the widely appeared problem—short of RAM on chip in embedded system, we deeply analyzed the factor which cause the rising of this problem, and bring forward the method that we can separate the task stacks and interrupt stacks in order to depress the use of RAM.Finally, testing and evaluating of this system is proposed.