Help with stm32f042/072 custom boards

I’d like to start new project with crystal-less USB capable stm32 (opensource dispencer for soldering pastes & fluxes). Interested in:

  • STM32F042F6P6 (must)
  • STM32F042F4P6 (optional)
  • STM32F072C8T6 (optional)

Required features:

  • upload/debug via ST-link/V2 (for development)
  • DFU upload (for user’s assembly)

Desired features:

  • Ability to use any RTOS with minimal features set (mbed prefered)

While STM32F103xx have “generic” configs, SOCs above are not available. I only found this boards:

  • disco_f072rb.json
  • nucleo_f042k6.json
  • nucleo_f072rb.json

Mbed has something for nucleo f042k6 & nucleo f072rb targets, but not clean how to define new ones.

Could you help with configs for listed SOCs?

  • minimal needed - board configs with stm32cube framework
  • desired (but optional and not urgent) - mbed support