Layered Component Based Embedded Real-time Software Framework Design

Since the1970’s, embedded real-time software is used in all kinds of fields. However, thereisn’t a unified method in the development process of embedded real-time software. Withoutconsistent engineering methods in analysis, design and programming, produce processes areinfluenced by personal experience and styles heavily. This is one of the main facts slowsdown the development of embedded real-time system technology.In reality, from60%to90%modules are used frequently as surpporting module in anembedded real-time system. On the other hand, many of these modules run in the same way,such as way to start (stop) a task, schedule methods of tasks and resources, method to realizeand execute state machines. Therefore, this paper studies a portable, reuseable, extensiblelayered component based embedded real-time software framework, RF for short. This paperdoes the following works mainly:Firstly, builds the framework model after analysis the common requirement of real-timesystem and a five-layered architecture pattern used in embedded real-time systems commonly.Framework includes platform interfaces (peripheral driver interface and operating systeminterface), component libraries (device component, infrastruce component andcommunication parts) and hot spots (HMI hot-spot and application hot-spot). Peripheralinterface makes framework MCU independent. OS interface makes framework independent ofconcrete OS. Device component controls onboard devices, such as liquid crystal displayersand memories. Infrastructure components are platform independent components, such asdatabases, timers, etc. Communication components are used to communicate with external system, such as MODBUS communication parts. The HMI hot-spot is used to realizehuman-machine interaction. Application hot-spot is used to extend the application in differentfields.Secondly, gives the detailed design of framework. Framework design sequence is from theboundary to internal, from down to up.Define the peripheral driver interface after introducingthe function. And then define the OS interface after introducing the OS basic function. HMI isa most important part designed by applying MVC pattern, state pattern, and template pattern.Describe the function of device layer and middleware component, and make a detailed designby apply observer pattern, proxy pattern and so on. Moreover, present a smart data pattern todesign smart data components.Finally è apply the framework to charging infrastructure products. The charging infrastructureincludes more than one embedded real-time system products, such as DC monitor, DC Post,AC Post and so on. Take AC post as an example to show how to apply the framework.The framework has been developed and has been put in use. It is portable, reusable andextensible. It boosts the the real-time software developed with modularization andspecialization.