RISC-V-based YOLOv3-tiny acceleration with runtime-reconfigurable systolic arrays and custom instructions

YOLOv3-tiny is widely used in edge-oriented object detection, but its deployment on resource-constrained platforms is limited by high computational cost and the limited flexibility of conventional processors. This paper presents a RISC-V-based acceleration framework for YOLOv3-tiny inference that combines a tightly coupled CPU-accelerator architecture with runtime-reconfigurable hardware support. A Hummingbird E203 core is integrated with a dedicated accelerator through the NICE interface, and 11 custom instructions are introduced for data movement, convolution control, and post-processing. The hardware adopts a runtime-reconfigurable systolic array supporting multiple convolution kernel sizes, together with activation, pooling, fully connected, and detection-oriented post-processing modules. The design is implemented on an Artix-7 FPGA and evaluated using a hardware-oriented YOLOv3-tiny workload, supplemented by module-level analysis and same-platform baseline comparisons. Experimental results show a 79.5% reduction in convolution execution time and a 4.89 × speed-up over the baseline RISC-V processor. Hardware-supported post-processing further reduces the cycle cost of sorting and IoU-related computation by 60.55% and 45.44%, respectively. These results demonstrate the effectiveness of the proposed processor-coupled acceleration architecture for YOLOv3-tiny-based detection inference on edge platforms.