CH573F

Background

THe CH573F is a relatively new, fairly powerful, little microcontroller. They're about USD 1.00 a piece on AliExpress, which makes them incredibly cheap for their abilities, which makes them an ideal replacement for my Arduinos to run my Christmas lights!

The documentation for the controller is fairly easy to read, though examples are few and far between and the SDK is mostly in Chinese, but that's what this project is for. True to form, this project has no dependencies on any 3rd party SDK or OS. It's completely bare metal from the ground up.

Specs

The CH573 has some pretty impressive specs for its price point. For the purposes of this project, it has:

• Royalty-free RISC-V core:
• 32-bit Qingke RISC-V processor WCH RISC-V3A
• RV32IMAC instruction set w/ hardware multiplication and division.
• System frequency from 32KHz up to 60MHz (Though I can only get 6.4MHz, 30MHz and 60MHz to work).
• 512K FlashROM
• 32KB application data
• UART
• 4 independent UART, with 8-level FIFO
• SPI support with DMA

Related Work

This project is very similar to:

• https://git.josher.dev/cgit/stm32l4.git/
• https://git.josher.dev/cgit/esp32-ws2812b.git/

Together they make up my microcontroller trio for my Christmas lights every year.

Setup

To compile this project, one needs a few things.

1. A RISC-V crosscompiler with Picolibc
2. An installed version of "Fiddle", which is my custom register-description-language, found at https://git.josher.dev/cgit/fiddle.git
3. ch-flash, or another WCH ISP.
4. Cmake

RISC-V Cross-compiler with Piclibc

The easiest way to get one of these is to use crosstool-ng with the default riscv32-picolibc-elf

  $ ct-ng riscv32-picolibc-elf
  $ ct-ng build
  $ ct-ng install

Fiddle

Fiddle is a program used to take language-agnostic register descriptions and compile them into usable source code. The register descriptions for this project are provided as fiddle (fdl) files.

The Fiddle compiler is implemented in Haskell using the Haskell stack build system. Install stack with:

  $ apt install stack

get fiddle:

  $ git clone https://git.josher.dev/cgit/fiddle.git
  $ cd fiddle
  $ stack install

This will compile and install fiddlec, which is required to build this project.

WCH ISP

There are many open source projects which can flash to the CH573F. I have one in my git grove, but they're easy to find if another one works better.

  $ git clone https://git.josher.dev/cgit/ch-flash.git
  $ cd ch-flash
  $ make

CMake

Install cmake through your package manager.

  $ apt install cmake

Compiling and Flashing

  $ git clone https://git.josher.dev/ch573.git
  $ cd ch573
  $ cmake -B build
  $ make -C build
  $ /path/to/ch-flash -f build/main.bin

To flash, disconnect the ch573 from USB, hold down the BOOT button, then re-connect it, ch-flash should automatically detect it and flash it. After that, it all should work.