Graph of Outputs in the Process of Synthesis Directed at CPLDs

The paper focuses on the methodology of designing a cyber physical systems (CPS) physical layer using programmable devices. The CPS physical layer can be implemented in programmable devices, which leads to a reduction in their costs and increases their versatility. One of the groups of programmable devices are complex programmable logic devices (CPLDs), which are great for energy-saving, low-cost implementations but requiring flexibility. It becomes necessary to develop mathematical CPS design methods focused on CPLD. This paper presents an original technology mapping method for digital circuits in programmable array logic (PAL)-based CPLDs. The idea is associated with the process of multilevel optimization of circuits dedicated to minimization of the area of a final solution. In the technology mapping process, the method of a multioutput function was used in the graph of outputs form. This method is well known from previous papers and proposes optimization of a basic form of the graph of outputs to enable better use of the resources of a programmable structure. The possibilities for the graph of outputs were expanded in the form of sequential circuits. This work presents a new form of a graph that describes the process of mapping and is known as the graph of excitations and outputs. This graph enables effective technology mapping of sequential circuits. The paper presents a series of experiments that prove the efficiency of the proposed methods for technology mapping. Experiments were conducted for various sizes of PAL-based logic blocks and commercially available CPLDs. The presented results indicate the possibility of more effective implementation of the CPS physical layer.