SLAU723A October 2017 – October 2018 MSP432E401Y , MSP432E411Y
When no activity has occurred on the USB bus for 3 ms, the USB controller automatically enters SUSPEND mode. If the SUSPEND interrupt has been enabled in the USB Interrupt Enable (USBIE) register, an interrupt is generated at this time. When in SUSPEND mode, the PHY also goes into SUSPEND mode. When RESUME signaling is detected, the USB controller exits SUSPEND mode and takes the PHY out of SUSPEND. If the RESUME interrupt is enabled, an interrupt is generated. The USB controller can also be forced to exit SUSPEND mode by setting the RESUME bit in the USB Power (USBPOWER) register. When this bit is set, the USB controller exits SUSPEND mode and drives RESUME signaling onto the bus. The RESUME bit must be cleared after 10 ms (a maximum of 15 ms) to end RESUME signaling.
To meet USB power requirements, the controller can be put into Deep Sleep mode which keeps the controller in a static state. Hibernation mode should not be used for SUSPEND mode because all internal state information is lost in hibernation.
NOTE
When configured as a self-powered device, the USB module meets the response timing and power draw requirements for USB compliance of SUSPEND mode. When configured as a bus-powered device, the USB can operate in SUSPEND mode but produces a higher power draw than required to be compliant.