Custom Soft-Core RISC Processor Validation Based on Real-Time Event Handling Scheduler FPGA Implementation

Abstract

In dynamic real-time systems (RTS), the synchronous communication model is a source of unpredictable behaviors caused by the difficulty of estimating the maximum lockdown time in a process. Inter-task communication is a critical issue in RTS, even in the case of uniprocessor architectures. Using an FPGA-based development platform, through an SoC project, the implementation of HW_nMPRA_RTOS (a unified acronym for multi pipeline register architecture (nMPRA) where $n$ is the degree of datapath resource multiplication, hardware scheduler engine (nHSE) for $n$ threads and RTOS application programming interface (API)), dedicated processor architecture was developed, simulated and validated. This paper proposes an innovative soft-core implementation to reduce interrupt latencies while maintaining strong spatial and temporal isolation. Among the results which contain relevance and novelty, we can mention: rapid tasks context switching (1 clock cycle); The implementation of a distributed and versatile interrupt system that allows the interrupt attachment to any task; The implementation of a static scheduler and support for the dynamic tasks scheduling; Rapid response to events of up to 2 clock cycles. We demonstrate the architecture’s predictability, scalability, and performance by running a set of benchmark applications on several configurations of HW_nMPRA_RTOS synthesized on a Xilinx 7 Series FPGA.

Keywords

• Hardware RTOS
• microprocessor
• scheduling
• field-programmable gate arrays (FPGA)
• real-time systems