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XMEGA A [MANUAL]
8077I–AVR–11/2012
13.8
Alternate Port Functions
Most port pins have alternate pin functions in addition to being a general purpose I/O pin. When an alternate function is
enabled, it might override the normal port pin function or pin value. This happens when other peripherals that require pins
are enabled or configured to use pins. If and how a peripheral will override and use pins is described in the section for
that peripheral.
accessible from software, but are internal signals between the overriding peripheral and the port pin.
Figure 13-11. Port override signals and related logic.
13.9
Slew Rate Control
Slew rate control can be enabled for all I/O pins individually. Enabling the slew rate limiter will typically increase the
rise/fall time by 50% to 150%, depending on operating conditions and load. For information about the characteristics of
the slew rate limiter, please refer to the device datasheet.
D
Q
R
D
Q
R
Synchronizer
D
Q
R
D
Q
R
DIRn
OUTn
PINnCTRL
INn
Pxn
D
Q
R
C
o
n
t
r
o
l
L
o
g
i
c
Digital Input Disable (DID)
Wired AND/OR
Slew Rate Limit
Digital Input Pin
Analog Input/Output
Inverted I/O
Pull Enable
Pull Keep
Pull Direction
DID Override Enable
DID Override Value
OUT Override Enable
OUT Override Value
DIR Override Enable
DIR Override Value