SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
The USB controller requires a total of three signals (D+, D-, and VBus) to operate in device mode and two signals (D+, D-) to operate in embedded host mode. Because of the differential signaling needed for USB, the D+ and D- pins have special buffers to support USB. As such, the position on the chip is not user-selectable. The D+ and D- pins at reset are, by default, GPIOs and must be configured before being used as USB function pins. Bits 10 and 11 in the GPIO B Analog Mode Select register (GPBAMSEL) must be set to choose the USB function. The signals USB bus voltage (VBUS), external power enable (EPEN), and power fault (PFLT) are not hardwired to any pin and some applications require these signals be implemented in software using a GPIO. Software that implements these signals is available in the USB software library.