Each core provides a different USBAPI

The Arduino Core API defines a very low level USB api in [api/USBAPI.h](https://github.com/arduino/ArduinoCore-API/blob/master/api/USBAPI.h). This API is implemented by the avr core in [cores/arduino/USBCore.cpp](https://github.com/arduino/ArduinoCore-avr/blob/master/cores/arduino/USBCore.cpp). But it is not implemented by samd core, which implements the same functionality but in its own [`USBDeviceClass` class](https://github.com/arduino/ArduinoCore-samd/blob/master/cores/arduino/USB/USBCore.cpp). The USB implementation in megaavr core (`USBCore.cpp`) is a copy of the avr usb implementation with some deviations. The mbed core implements its own version of the `PluggableUSBModule`.

As a result, each core implements its own USB API which is incompatible with the others, there exist many code duplicates and users of the USB API have to understand and adapt their code to each individual core implementation.

Are there any plans to improve this situation?

Comienza con api/USBAPI.h y compara las implementaciones en las rutas de core avr, samd, megaavr y mbed mencionadas en el issue, incluidos USBCore.cpp, USBDeviceClass y PluggableUSBModule. El issue no define un cambio concreto, así que primero establece el alcance de compatibilidad previsto; el trabajo estaría terminado cuando se acuerde una API USB común entre los cores afectados.

Escrito por el modelo de indexación a partir del texto del issue.