The alternative SDK for Apollo1 and Apollo2 was launched. The same SDK can be used for Apollo 1 and 2. Target is to be fully CMSIS compatible and make use of CMSIS compatible headfiles and register access as defined in CMSIS. In case of using core features like NVIC or ARM instructions like __NOP(); the library will use valid CMSIS defined APIs compatible for all different ARM compilers. Target of the library is to use C language, so it is compatible as much as possible and must not be ported for each ARM Cortex M compatible compiler.
The roadmap is to support CMSIS driver API as one of the next steps.
The source can be found here:
A documentation will be provided soon. Collaboration is welcome!