使用特徵代數對電子元件進行語義建模：案例研究

本論文以實際元件的資料單(datasheet)做為建立出適用於特徵導向的嵌入式系統設計方法所使用的元件含義模型。特徵導向設計使用特徵代數來表達特徵之間橫向與縱向的關係，其目的為捕捉機制在設計裡的意義。此設計方法的優勢包括容易替換機制、容易演進、同時讓演算法能自動檢查需求滿足的完整性與自動提示。但是，要實現優勢的前提，就是工具依賴的元件庫必須提供豐富的元件模型，以上述方式捕捉根據資料單裡描述的相關資訊。雖然業界的電子化資料單已有提出，也針對不同領域提供，包括封裝、功耗、電、時間、邏輯介面、暫存器表、和函式等等。但是，絕大都是以相對低階方式，如鍵值組表達參數值，缺乏機制的意義部份，而語義的表達則是資工領域裡最有挑戰性的問題之一。本研究提出一種使用特徵代數(feature algebra)做為建立元件意義模型的表達特徵間橫向與縱向關係方式。特徵代號可參考本體論的概念，而運算元可將不同特徵做橫向組合或表達縱向概含與實現的關係。元件介面則是將高階特徵對應到一種稱為旗標圖(semagraph)的模型，以精確、精簡的方式捕捉電路圖裡現有與從缺的連線。我們的實例是根據一個系統晶片的多模態感測器的資料單為特徵依據。該元件支援兩種通訊協定可選其中之一與微控器介面，而且這個元件涵蓋了許多嵌入式系統使用到的代表性的特徵。本研究產出的模型的目的是要顯示出從實際元件的資料單裡萃取出關鍵資訊以建立出支援特徵導向設計的可行性。

關鍵字

嵌入式系統；特徵模型；電子設計自動化；電腦代數系統；電子元件模型；語義建模

並列摘要

This thesis presents a case study of capturing information in a component datasheet in a semantic model suitable for feature-based design of embedded systems. Feature-based design is a new methodology that uses feature algebra to express the relationships between features, both vertically and horizontally, such that mechanisms in a design are associated with the semantics. The benefits include enhanced retargetability and evolvability as well as enabling automatic checking of requirement fulfillment and prompting. However, these potentials will not be fully realized unless the methodology is well supported by a library of component models that capture all the knowledge in the datasheet. Datasheets have been captured in electronic format for several different domains, including physical packaging, power, electrical, timing, logical interfacing, register map, and functions. While many lower-level domains can be captured parametrically as key-value pairs without much interpretation, the semantics of the functions remains one of the most challenging problems in computer science. This research proposes to use feature algebra to capture the horizontal and vertical relationships between features in a component semantically. Feature symbols can refer to the ontological models, and operators either compose features horizontally or express concept-manifestation relationships vertically. At the interface level, our feature model is related to a graph model called semagraph that captures existing and potential states of connection in a precise and concise representation. Our case study is a system-on-chip (SoC) of multiple sensors that can be interfaced with a microcontroller via two alternative protocols, and it covers the representative features of most components for embedded systems. The resulting model demonstrates the feasibility of modeling key information extracted from the actual datasheet to support the novel feature-based design methodology.