This patch allows to completely compile-out support for USB, and no-USB is
now the default. If a board wants to enable USB it should define:
#define MICROPY_HW_ENABLE_USB (1)
And then one or more of the following to select the USB PHY:
#define MICROPY_HW_USB_FS (1)
#define MICROPY_HW_USB_HS (1)
#define MICROPY_HW_USB_HS_IN_FS (1)
Header files that are considered internal to the py core and should not
normally be included directly are:
py/nlr.h - internal nlr configuration and declarations
py/bc0.h - contains bytecode macro definitions
py/runtime0.h - contains basic runtime enums
Instead, the top-level header files to include are one of:
py/obj.h - includes runtime0.h and defines everything to use the
mp_obj_t type
py/runtime.h - includes mpstate.h and hence nlr.h, obj.h, runtime0.h,
and defines everything to use the general runtime support functions
Additional, specific headers (eg py/objlist.h) can be included if needed.
This is to keep the top-level directory clean, to make it clear what is
core and what is a port, and to allow the repository to grow with new ports
in a sustainable way.
