skSoC: a RISC-V Hazard3 based SoC skeleton

This paper presents skSoC, a new open source SoC skeleton for FPGAs. More precisecly, the skSoC is a small yet powerful SoC skeleton targeted towards FPGAs with a reduced number of LUTs, such as those used in embedded systems. It offers access to as much RAM memory as needed, interfaced to the Arm AHB AMBA bus. skSoC is written in Verilog and based on Hazard3, a well-known RISC-V processor implementation also used in Raspberry Pi Pico 2. It incorporates a microSD Verilog driver along with a hardware written boot loader. The system is implemented and tested on the Tang nano 20k FPGA board and runs the Apache Nuttx real time operating system.