Connect RS-485 to USART2

 SAM3X PB20 TXD2 to RS-485 D
 SAM3X PB21 RXD2 to RS-485 R
 SAM3X PB22 RTS2 to RS-485 DE

 Daisy chain detection lines connected
 PC11 to DAISY_DETECT_PREVIOUS
 PC12 to DAISY_DETECT_NEXT
 PC13 to DAISY_ENUMERATION_IN
 PC19 to DAISY_ENUMERATION_OUT