SentryCore: A RISC-V Co-Processor System for Safe, Real-Time Control Applications

Abstract

SentryCore is a reliable, open-source RISC-V co-processor system (mega-IP) designed for advanced, real-time control functions in safety-critical applications like automotive and robotics. It ensures reliability by using three embedded RISC-V cores operating in lockstep with ECC-protected memory. The system is engineered for high performance, featuring hardware-accelerated context switching under 110 clock cycles and integrating seamlessly into Systems-on-Chip via AXI4.

Report

SentryCore: A RISC-V Co-Processor System for Safe, Real-Time Control Applications

Key Highlights

• Open-Source Mega-IP: SentryCore is presented as an open-source, vendor-neutral, self-contained mega-IP leveraging the growing RISC-V ecosystem.
• Target Application: Designed specifically for complex, safety-critical control systems (e.g., industrial automation, robotics, and automotive applications).
• Lockstep Architecture: Features three embedded RISC-V processor cores running in lockstep to ensure reliable execution and fault tolerance.
• Real-Time Performance: Achieves exceptionally fast context switching, completed in under 110 clock cycles, facilitated by custom hardware extensions.
• Implementation: Successfully fabricated and tested using Intel's 16nm process node.

Technical Details

• Reliability Features: Functional safety is achieved through triple-core lockstep operation combined with Error-Correcting Code (ECC) protection on data memory.
• Integration Standard: The system is designed for seamless integration into larger Systems-on-Chip (SoCs) via the industry-standard Advanced eXtensible Interface 4 (AXI4).
• Context Switching Acceleration: Fast switching is enabled by the RISC-V Core-Local Interrupt Controller (CLIC) coupled with dedicated hardware extensions.
• Data Pipeline: Includes a specialized timer-based Direct Memory Access (DMA) engine to efficiently streamline sensor data readout required for fast, periodic control loops.
• Software Support: The platform has been validated with several common real-time operating systems (RTOS), including FreeRTOS, ThreadX, and RTIC.

Implications

• Driving RISC-V Safety Adoption: SentryCore provides a tangible, high-reliability reference platform that accelerates the adoption of open-source RISC-V solutions in demanding safety-critical domains (which traditionally rely on proprietary, certified architectures).
• Meeting Mixed-Criticality Needs: By offering inherent fault tolerance (lockstep cores) and guaranteed real-time behavior (accelerated context switching), the IP addresses the escalating complexity of heterogeneous mixed-criticality systems (MCSs).
• Ecosystem Maturity: The successful implementation in Intel's 16nm process and validation across multiple mainstream RTOS platforms demonstrates the growing commercial maturity and readiness of the RISC-V ecosystem for industrial and automotive deployment.