Compiling for STM32C0xx w/ CMSIS

Reading about STM32C0 support in the Howto select STM32C011 MCU? post, I am able to compile for the STM32C011F6 using the Arduino and STM32Cube frameworks. which is excellent news. When following that very last entry ( Howto select STM32C011 MCU? - #20 by webdust21 ), quite a few things get installed, which I don’t need.

I’d like to find to a simpler approach, compiling for the cmsis framework instead, as I’ve been doing for lots of other STM32 boards, but right now this fails:

CONFIGURATION: https://docs.platformio.org/page/boards/ststm32/genericSTM32C011F6.html
PLATFORM: ST STM32 (19.4.0) > Generic STM32C011F6
HARDWARE: STM32C011F6P6 48MHz, 6KB RAM, 32KB Flash
DEBUG: Current (blackmagic) External (blackmagic, jlink, stlink)
PACKAGES:
 - framework-cmsis @ 2.50501.200527 (5.5.1)
 - framework-stm32cubec0 @ 1.4.0+sha.741db43
 - tool-ldscripts-ststm32 @ 0.2.1+sha.3126213
 - toolchain-gccarmnoneeabi @ 1.140201.0 (14.2.1)
KeyError: 'framework-cmsis-stm32c0':

Is there a way to construct this missing package? I found https://github.com/Open-CMSIS-Pack/STM32C0xx_DFP , but I don’t know to get from there to a suitable set of files.

Ideally, I’d like to submit a patch on github to help get C0 series support into PIO.

PS. The other thing I don’t understand is this notation for platformio_packages:

   tool-openocd@symlink://packages/xpack-openocd-0.12.0-3-win32-x64

Is it a symbolic link to an area in .platformio/? What does the tool-openocd@ prefix do?

Update: also found this GitHub - STMicroelectronics/cmsis-device-c0: Provides the STM32Cube MCU Component "cmsis_device_c0" of the STM32C0 series. · GitHub - which looks more like how the G0 series is integrated in PlatformIO.

Doh: fork, add a suitable package.json, commit, and then add this line to platformio.ini:

framework-cmsis-stm32c0@https://github.com/jcw/cmsis-device-c0

(as part of the other platform_packagessettings)