SLAU723A October 2017 – October 2018 MSP432E401Y , MSP432E411Y
To conserve power, the USB On-The-Go (OTG) supplement allows VBUS to only be powered up when required and to be turned off when the bus is not in use. VBUS is always supplied by the A device on the bus. The USB OTG controller determines whether it is the A device or the B device by sampling the ID input from the PHY. This signal is pulled LOW when an A-type plug is sensed (signifying that the USB OTG controller should act as the A device) but taken HIGH when a B-type plug is sensed (signifying that the USB controller is a B device). Note that when switching between OTG A and OTG B, the USB controller retains all register contents.