/**
* @brief ignore vbus detection, only available in at32f415xx revision C.
* at32f415xx revision B: (not support)
* the vbus detection pin (pa9) can not be used for other functionality.
* vbus pin must kept at VBUS or VDD.
*
* at32f415xx revision C: (support)
* ignore vbus detection, the internal vbus is always valid.
* the vbus pin (pa9) can be used for other functionality
*/
#define USB_VBUS_IGNORE