The Design of Optimized RISC Processor for Edge Artificial Intelligence Based on Custom Instruction Set Extension

Edge computing is becoming increasingly popular in artificial intelligence (AI) application development due to the benefits of local execution. One widely used approach to overcome hardware limitations in edge computing is heterogeneous computing, which combines a general-purpose processor with a domain-specific AI processor. However, this approach can be inefficient due to the communication overhead resulting from the complex communication protocol. To avoid communication overhead, the concept of an application-specific instruction set processor based on customizable instruction set architecture (ISA) has emerged. By integrating the AI processor into the processor core, on-chip communication replaces the complex communication protocol. Further, custom instruction set extension (ISE) reduces the number of instructions needed to execute AI applications. In this paper, we propose a uniprocessor system architecture for lightweight AI systems. First, we define the custom ISE to integrate the AI processor and GPP into a single processor, minimizing communication overhead. Next, we designed the processor based on the integrated core architecture, including the base core and the AI core, and implemented the processor on an FPGA. Finally, we evaluated the proposed architecture through simulation and implementation of the processor. The results show that the designed processor consumed 6.62% more lookup tables and 74% fewer flip-flops while achieving up to 193.88 times enhanced throughput performance and 52.75 times the energy efficiency compared to the previous system.