For a successful build the following changes are required:

In halconf.g (in both nanoBooter and nanoCLR folders), when compared with a default file:

• HAL_USE_SERIAL to TRUE
• HAL_USE_SERIAL_USB to TRUE
• HAL_USE_USB to TRUE
• SERIAL_DEFAULT_BITRATE to 921600

In mcuconf.h (in both nanoBooter and nanoCLR folders), when compared with a default file:

• STM32_SERIAL_USE_USART2 to TRUE
• STM32_USB_USE_OTG1 to TRUE

In chconf.h (only for nanoCLR folder), when compared with a default file:

• set the CORTEX_VTOR_INIT with the appropriate address of the vector table for nanoCLR

Any defines specific to an image (nanoBooter or nanoCLR) that are to be made available throughout the code should be added to the target_board.h.in. There is one in nanoBooter and another in nanoCLR directories, allowing different defines for each one. Defines that are common to a target board should be added to the target_common.h.in. The content of these files is parsed by CMake. It can include CMake variables. Check the documentation of CMake config files here.

NOTE: this configuration was successfully tested in a ST_STM32F429I_DISCOVERY board using the Serial over USB connection on USB port 1 that creates a virtual COM port.

The current build is set to add support for single-precision floating point. Meaning that System.Math API supports only the float overloads. The double ones will throw a NotImplementedException.