README.md

WCH_V307_RISC-V

Bare metal programming on WCH RISC-V MCU CH32V307VCT6 board (CH32V307V-EVT-R1)

This repository implements an entirely manually-written, pure bare metal Blinky Project for the SiFive RISC-V MCU CH32V307VCT6 board (CH32V307V-EVT-R1).

Features include:

• CPU, power, chip, clock and PLL initialization,
• timebase derived from the R32_STK timer,
• blinky LED show with adjustable frequency,
• implementation in C99 with absolute minimal use of assembly.

Clear and easy-to-understand build systems based on either GNUmake or CMake complete this fun and educational project.

This repository provides keen insight on starting up a bare metal SiFive RISC-V controller. It emphasizes simplicity and independence from monolithic toolchains through its lightweight, self-written implementation.

Details on the Application

The application boots from a tiny startup code in the boot ROM.

Following low-level chip initialization, the program jumps to the main() subroutine. Here the timer interrupt is setup for LED blinky.

The adjustable LED-phase (its half-period) can be tuned to provide a rudimentary, visible blinky LED show. The timebase for blinky is based on the R32_STK timer with an interrupt handler once per second.

Blinky running on the target is shown in the image below. A wire is required connecting port pins PC0 and LED1 in order to observe the blinky toggle. See the orange wire in the picture.

Building the Application

Build on *nix* is easy using gcc-riscv32-unknown-elf

Both classic GNUmake as well as CMake can be used to build the Application:

cd WCH_V307_RISC-V/Build

GNUmake

./Rebuild.sh

CMake

mkdir Output && cd Output
cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/toolchain-unix.cmake .. && make

The build results including ELF-file, HEX-mask, MAP-file and assembly list file are created in the Output directory.

If gcc-riscv32-unknown-elf is not installed, it can easily be obtained from embecosm. If necessary, add the path of the RISC-V GCC tools' bin folder to $PATH in the usual *nix way.

Continuous Integration

CI runs on pushes and pull-requests with simple build(s) including result verification on ubuntu-latest and macos-latest using GitHub Actions.

Licensing

• The source and build code written for this repo are licensed under The Unlicense.
• The system-register file riscv-csr.h, originally from five-embedded, is also licenced under The Unlicense.