An Asynchronous Interface with Robust Control for Globally-Asynchronous Locally-Synchronous Systems

Duarte Lopes Oliveira, Eduardo Lussari, Sandro Shoiti Sato, Lester Abreu Faria

Abstract


http://dx.doi.org/10.5028/jatm.v5i1.191

Contemporary digital systems must necessarily be based on the “System-on-Chip” (SoC) concept. Especially in relation to the aerospace industry, these systems must overcome some additional engineering challenges concerning reliability, safety and low power. An interesting style for aerospace SoC design is the GALS (Globally Asynchronous, Locally Synchronous) paradigm, which can be used for Very Large Scale Integration – Deep-Sub-Micron (VLSI_DSM) design. Currently, the major drawback in the design of a GALS system is the asynchronous interface (asynchronous wrapper – AW) when being implemented in VLSI_DSM. There is a typical AW design style based on asynchronous controllers that provides communication between modules (called ports), but the port controllers are generally subjected to essential hazard, what decreases the reliability and safety of the full system. Concerning to this main drawback, this paper proposes an AW with robust port controller that shows to be free of essential hazard, besides allowing full autonomy for the locally synchronous modules, creating fault tolerant systems as much as possible. It follows the Delay Insensitive (DI) model interacting with the environment in the Generalized Fundamental Mode (GFM) without the need to insert any delay elements. Additional delay elements, although proposed by some previous work found in literature, are not desirable in aerospace applications. The proposed interface allows working on Ib/Ob mode, showing the DI model is more robust than the QDI model and, therefore, it does not need to meet isochronic fork requirements nor timing analysis. Once an interface presenting similar properties was not found in literature, the proposed architecture proved to have great potential of implementation in practical VLSI_DSM designs, including the aerospace ones, once it overcomes the main engineering challenges of this kind of industry.


Keywords


Aerospace systems; Reliability; Low power; Asynchronous controllers; GALS.

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