SLAZ312AD October 2012 – May 2021 MSP430F5527
USB Module
Functional
USB control registers cannot be modified during USB Function Reset when FRSTE = 1
If the function reset connection enable (FRSTE) bit in the USBCTL register is set and the USB host asserts reset over the USB bus, then the USB control registers cannot be modified until the host reset is de-asserted. The FRSTE bit is used to enable the USB function reset to reset of all internal logic of the USB module and is used to reduce the software overhead of USB reset handling.
Clear the FRSTE bit inside the RSTRIFG interrupt service routine before reconfiguring the USB control registers, and set the FRSTE bit at the beginning of SUSRIFG, SETUPIFG, IEPIFG.EP0, and OEPIFG.EP0 interrupt service routines.
NOTE: TI supplied stacks implement this software workaround