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Modern cyber-physical systems often make use of heterogeneous systems-on-chip with reconfigurable logic to provide adequate computing power and flexible I/O. However, modeling, verifying, and implementing the computations spanning CPUs and reconfigurable logic are still challenging. The hardware and software components are often designed by different teams and at different levels of abstraction, making it hard to reason about the resulting computation. We propose to lift both hardware and software design to the same level of abstraction by using the Lingua Franca coordination language. Lingua Franca is based on a sparse synchronous model that allows modeling concurrency and timing while keeping a sequential model for the actual computation. We define hardware reactors as a subset of the reactor model of computation underlying Lingua Franca. We also present and evaluate reactor-chisel, a hardware runtime implementing the semantics of hardware reactors, and an extension to the Lingua Franca compiler enabling reactor-oriented hardware–software codesign. 

Abstract—Lingua Franca is a programming paradigm that eases the development of distributed cyber-physical systems and ensures determinism. These systems are subject to stringent timing constraints, generally expressed as task deadlines, and meeting them requires real-time scheduling. This work presents a layered scheduling strategy for Lingua Franca for enhanced real-time performance that builds upon any priority-based operating system thread scheduler. The application designers need to specify only the application-specific deadlines, and the Lingua Franca runtime automatically converts them into appropriate priority values for the OS scheduler to obtain earliest deadline first scheduling. 

This paper introduces software-defined watchdogs, a programming model for handling faults that manifest as delayed or missing signals. The programming model is implemented as an extension to the polyglot coordination language Lingua Franca, where it acts as an eager deadline for delayed inputs. The technique is compared against hardware-defined watchdogs and software watchdogs in other reactive languages.