# FreeRTOS demo for WCH CH32V30x series MCU

## How to use
* Write your own CMake toolchain file (see `xpack-riscv.cmake` for example)
* Configure project and build as usual. (see below for a simple test)

## Sample usage

### build project

```bash
cmake -S . -B build -G Ninja
cmake --build build
```

### flash binary

Enter the isp mode: 
press `reset` and `boot0` key at the same time. Release `reset` key then `boot0` key.

```
cmake --build build -t flash
```

## Notes

### Startup files
There are two versions of startup assembly files, located at
* `BSP/Startup/startup_ch32v30x_D8.S`
* `BSP/Startup/startup_ch32v30x_D8C.S`

The first file is used for CH32V303 devices, which lacks of the following peripherals:
* Ethernet
* CAN2
* USBHS
* DVP

*** Change the startup file to the correct version for the hardware in use. ***

### Compilers
These MCUs uses something called "RISC-V4F" core with Chinese documentation provided:
* Implemented RV32IMAFC ABI

Here is the list of features proprietary or incompatible with upstream toolchain:
* Fast IRQ handlers: uses a special attribute of `interrupt`, which value is `WCH-Interrupt-fast`

## References

* https://github.com/gregdavill/CH32V307-makefile-example
* https://git.minori.work/Embedded_Projects/CH32V307_FreeRTOS_Hello
* https://git.minori.work/Embedded_Projects/CH32V307_Template
* https://github.com/imi415/FreeRTOS-Kernel.git
* https://github.com/hathach/tinyusb
* https://github.com/riscv-collab/riscv-gnu-toolchain