Design and Implementation of a RISC V Processor on FPGA

The RISC-V ISA is becoming one of the leading instruction sets for the Internet-of-Things and System-on-Chip applications. Due to its strong security features and open-source nature, it is becoming a competitor to the popular ARM architecture. This paper describes the design of a light weight, open-source implementation of a RISC-V processor using modern hardware design techniques, the implementation of the design onto a Field Programmable Gate Array (FPGA), and its testing. We wanted to create a RISC-V processor that is easy for beginners to learn from and lightweight enough to be implemented on even small FPGAs. While there are existing opensource implementations of RISC-V processors, none are intuitive enough for a beginner to follow. For this reason, in this paper we have minimised the use of conventions and components in modern processors that are not strictly necessary for a barebones implementation. For example, the processor does not include pipelining and uses a simple Harvard architecture. The barebones nature of the design allows for a lot of potential for upgradability. The implementation of each component, and the corresponding test benches, are written in concise and conventional System Verilog. The project produced a RISC-V processor with files for targeting Basys 3 Artix-7 FPGA. Performance was tested using the Dhyrstone benchmark and achieved a strong 2.276 DMIPs/MHz, even outperforming the ARM Cortex-A9, while maintaining very low resource utilization on the FPGA.