RISCky_CORE

Overview

Verilog implementation of a RISC-V core for FPGA. At the current state the core implements all of the basic RV32I instructions in a non-pipelined fashion.

The current core is already divided into the five major execution phases:

• (IF) Instruction Fetch
• (ID) Instruction Decoding
• (EX) Execute
• (MEM) Memory
• (WB) Write BACK

Each phase's implementation can be found inside the respective folder. This structure aims to for an easier switch to a pipelined core later down the line.

Result of simulation on test program

RV32I ISA Test Program

Testing Register-Register Ops... ############## PASSED

Testing Register-Immediate Ops... ########### PASSED

Testing load/store Operations... ##### PASSED

Testing Control Flow... ######## PASSED

Testing LUI/AUIPC Operations... ## PASSED

Roadmap

0. • RV32I
1. • Zicsr
2. • Zifencei
3. • RV32IM
4. • RV32IMA
5. • RV32IMAF/D (RV64G)
6. • RV32IMADC (RV64GC)

Hardware

The hardware target is an FPGA TangPrimer 20k, but developement is mainly focused towards working simulation at the moment.

Toolchain

• For FPGA building toolchain is based on the OSS-CAD-SUITE
• For simulation iverilog is used

Sources

• https://github.com/sipeed/sipeed_wiki/tree/main/docs/hardware/en/tang/tang-primer-20k

• https://github.com/sipeed/TangPrimer-20K-example

• https://github.com/YosysHQ/apicula/wiki

• https://chipmunklogic.com/digital-logic-design/designing-pequeno-risc-v-cpu-from-scratch-part-4-fetch-unit/

• https://pyjamabrah.com/posts/writing-a-risc-v-cpu/

• https://vhdlwhiz.com/how-the-axi-style-ready-valid-handshake-works/

• https://zipcpu.com/blog/2021/08/28/axi-rules.html

• https://github.com/BrunoLevy/learn-fpga/blob/master/FemtoRV/TUTORIALS/FROM_BLINKER_TO_RISCV/README.md

• https://fpgacpu.ca/fpga/handshake.html

• https://www.asic-world.com/verilog/index.html

• https://hdlbits.01xz.net/wiki/Main_Page

• https://gitea.auro.re/higepi/Projet_SETI_RISC-V/raw/branch/main/Doc/Design_and_Implementation_of_a_RISC_V_Processor_on_FPGA.pdf

• https://v2kparse.sourceforge.net/includes.pdf

• https://www.01signal.com/verilog-design/arithmetic/signed-wire-reg/

• https://cva6.readthedocs.io/en/latest/01_cva6_user/RISCV_Instructions_RV32I.html

• https://www.ustcpetergu.com/MyBlog/experience/2021/07/09/about-riscv-testing.html

• https://riscv.github.io/riscv-isa-manual/snapshot/unprivileged/

• https://riscv.github.io/riscv-isa-manual/snapshot/privileged/

• https://www.fpga4fun.com/SD1.html

• https://electrobinary.blogspot.com/2020/06/control-and-status-registers-csr.html

• https://electrobinary.blogspot.com/p/verilog.html

• nand2mario/nestang#2

• trabucayre/openFPGALoader#300