实时、交互嵌入式系统的频率推导问题

Rate Derivation of Real-time Interactive Embedded System

嵌入系统在严格的时间约束(外部约束)下连续地与外界环境相互作用,把这些外部约束转换成系统任务的时间预算(内部约束)是非常重要的。知道这些时间预算能降低系统设计与验证问题的复杂度,并有助于设计者对系统的功能和时间正确性从设计的一开始就能同步地控制。转换用系统的任务结构和从环境对系统的输入刺激的频率推导系统中每个任务的频率,推导出的任务频率被用来推导和验证其余的内部和外部约束。提出了一个广义任务图模型去表示系统的任务结构,并给出了推导和验证系统时间约束的方法和一个把它们融合在一起的硬件/软件协同设计方法。

An embedded system react s continuously with its environments under strict timing constraints(called exter nal constraint ),and it is important to translate these external constraints to time budgets.It is known that these time budgets reduces the complexity of system's design and validation problem and helps the designer simultaneously to control over the system's functional and temporal correctness from the beginnin g of the system design flow.The translation is carried out by deriving the rat e of each task using the system's task structure and the rates of input stimuli from its environments.The derived task rates are used to derive and validate t he rest internal and external constraints.A general task graph model is propose d to represent system's task structure in this paper,and a hardware/software codesign method of putting the derivation and validation of the embedded system together.