SLAU723A October 2017 – October 2018 MSP432E401Y , MSP432E411Y
When using the device controller portion of the USB controller in a system that also provides host functionality, the power to VBUS must be disabled to allow the external host controller to supply power. Usually, the USB0EPEN signal is used to control the external regulator and should be negated to avoid having two devices driving the USB0VBUS power pin on the USB connector.
When the USB controller is acting as a host, it is in control of two signals that are attached to an external voltage supply that provides power to VBUS. The host controller uses the USB0EPEN signal to enable or disable power to the USB0VBUS pin on the USB connector. An input pin, USB0PFLT, provides feedback when there has been a power fault on VBUS. The USB0PFLT signal can be configured to either automatically negate the USB0EPEN signal to disable power, andit can generate an interrupt to the interrupt controller to allow software to handle the power fault condition. The polarity and actions related to both USB0EPEN and USB0PFLT are fully configurable in the USB controller. The controller also provides interrupts on device insertion and removal to allow the host controller code to respond to these external events.