Hi,
I was reading Data sheet of ATXMEGA16D4 MCU( XMEGA D [MANUAL] 110
Atmel-8210G AVR XMEGA D 12/2014) and at page 110 they have said
"DIR This register sets the data direction for the individual pins of the port. If DIRn is written to one, pin n is configured as an output pin. If DIRn is written to zero, pin n is configured as an input pin."
"DIRSET This register can be used instead of a read-modify-write to set individual pins as output. Writing a one to a bit will set the corresponding bit in the DIR register. Reading this register will return the value of the DIR register.
"
"DIRCLR This register can be used instead of a read-modify-write to set individual pins as input. Writing a one to a bit will clear the corresponding bit in the DIR register. Reading this register will return the value of the DIR register.
"
These registers have diffrent address, What is the principle of association and how is it mapped? Where can I find it?
I notice that 
I find some information from https://www.avrfreaks.net/forum/... ,But that is not the answer I want













