If your CPU doesn’t emulate one of these protocols you either have to develop your own driver or change the platform as I noted earlier. The current host shield software supports FTDI, ACM, PL2303 and the rather exotic XR21B1411. I’m definitely no Microsoft specialist but in my understanding the Microsoft Serial Port Driver is only responsible for an actual hardware serial interface (the chip once was 16550, no it’s usually in a mainboard chip but has the same functionality). You can use the SPI interface only if you're able to change the firmware running on that MCU. The type of serial interface we were talking about is an asynchronous serial interface (UART style). It has a built in serial interface (SPI). I know that chip is a microcontroller, but the USB port goes directly to that chip. If your CPU doesn't emulate one of these protocols you either have to develop your own driver or change the platform as I noted earlier. Very common representatives of this category are FTDI, ACM, PL2303 and recently CH340, none of them has a driver originating from Microsoft to my knowledge.

To use a virtual serial port provided by a USB device you need an additional driver. I'm definitely no Microsoft specialist but in my understanding the Microsoft Serial Port Driver is only responsible for an actual hardware serial interface (the chip once was 16550, no it's usually in a mainboard chip but has the same functionality). If works perfectly with the default Microsoft Serial Port driver, so I guess I'm lukcy.

Usb to serial mac command