Embedded System Development Platform - The Design And Realization Of The Core Layer

An embedded system developing platform which supports embedded systemresource reusage, reduces embedded system developing period and improvedeveloping efficiency is an effective utility for embedded product developing.However, embedded system is application-oriented developed, different functionsare embedded in different products. And great real time performance is needed inmost application projects. It has been a critical and urgent problem for currentembedded system development to properly design and realize the real time abilityand configurability of embedded system.In this paper, the main research focuses on the analysis and realization of thekernel layer based on layer modeled embedded system developing platform. Kernellayer is an important layer that concerns task management, exception and interruptmanagement, memory management and so on, whose function is to realize the realtime operation system kernel. Based on the present embedded real time operationsystems and their real time and configurable abilities, a new approach is proposedand realized.The embedded system developing platform consists of three modules: taskmanagement module, exception and interrupt management module and memorymanagement module.In task management module, task controlling block (TCB) is designed: The taskstatuses are classified in detail. Through utilizing the ready line and setting up thetask scheduling variables, the real time performance of task scheduling is improved.Through utilizing the task controlling block, signal, semaphore signal, event flaggroup, event mailbox, message line and other approaches in parallel controlling, thecoordination between running tasks is realized.In exception and interrupt management module, exception handling principle isanalyzed, and the interfaces of exception handling function and program exceptionhandling function between ESP-HAL and kernel layer are designed. Interruptprocessing model, interrupt handling procedure and interrupt processing serviceinterface are given and designed. Besides, the functions of exception and interruptmanagement are designed with library function and C language macro interface forprogrammer, which also cut the responding time of exception and interrupt handling.In memory management module, based on the realization of memory controllingblock, every memory block can be traced, and memory area can be realized byunique memory block management techniques, which effectively prevent thecausing of memory fragment.With the support of independent developing embedded system developingplatform in this research, kernel layer can realize the functions of embedded realtime operation system. Compared with present embedded real time operation systemcounterpart, this kernel can offer better real time and configurable performances andsatisfy the needs to develop embedded system.