7.1.3.5 USB IO & Power Management
Address = 39-3Bh (read), 39h (write), 3Ah (set), 3Bh (clear)
SwapDP/DM 1 rd/w/s/c 0b
When asserted, the DP and DM pins of the USB
transceiver are swapped. This bit can be used to
prevent crossing the DP/DM traces on the board. In
UART mode, it swaps the routing to the DP and DM
pins. In USB Audio Mode, it does not affect the
SPK_L and SPK_R pins.
http://ww1.microchip.com/downloads/en/D ... c/334x.pdf page 82.
Thank you