ATXMEGA128B1 Datasheet, PDF (31/138 Pages) ATMEL Corporation – 8/16-bit Atmel XMEGA B1 Microcontroller

15.4
Input sensing
Input sensing is synchronous or asynchronous depending on the enabled clock for the ports, and the configuration is
shown in Figure 15-7 on page 31.
Figure 15-7. Input sensing system overview
Asynchronous sensing
EDGE
DETECT
Interrupt
Control
IREQ
Pn
INVERTED I/O
Synchronizer
INn
D QD Q
RR
Synchronous sensing
EDGE
DETECT
Event
When a pin is configured with inverted I/O, the pin value is inverted before the input sensing.
15.5
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. “Pinout and Pin Functions” on page 52 shows which modules on peripherals that enable alternate
functions on a pin, and which alternate functions that are available on a pin.
XMEGA B1 [DATASHEET] 31
8330C–AVR–07/2012