76
8023F–AVR–07/09
ATmega325P/3250P
XCK/AIN0/PCINT2 – Port E, Bit 2
XCK, USART0 External Clock. The Data Direction Register (DDE2) controls whether the clock is
output (DDE2 set) or input (DDE2 cleared). The XCK pin is active only when the USART0 oper-
ates in synchronous mode.
AIN0 – Analog Comparator Positive input. This pin is directly connected to the positive input of
the Analog Comparator.
PCINT2, Pin Change Interrupt Source 2: The PE2 pin can serve as an external interrupt source.
TXD/PCINT1 – Port E, Bit 1
TXD0, UART0 Transmit pin.
PCINT1, Pin Change Interrupt Source 1: The PE1 pin can serve as an external interrupt source.
RXD/PCINT0 – Port E, Bit 0
RXD, USART0 Receive pin. Receive Data (Data input pin for the USART0). When the USART0
Receiver is enabled this pin is configured as an input regardless of the value of DDE0. When the
USART0 forces this pin to be an input, a logical one in PORTE0 will turn on the internal pull-up.
PCINT0, Pin Change Interrupt Source 0: The PE0 pin can serve as an external interrupt source.
Note:
1. CKOUT is one if the CKOUT Fuse is programmed
Table 13-9.
Overriding Signals for Alternate Functions PE7:PE4
Signal Name
PE7/PCINT7
PE6/DO/
PCINT6
PE5/DI/SDA/
PCINT5
PE4/USCK/SCL/
PCINT4
PUOE
0
USI_TWO-WIRE
PUOV
0000
DDOE
0
USI_TWO-WIRE
DDOV
1
0
(SDA + PORTE5)
DDE5
(USI_SCL_HOLD
+ PORTE4)
DDE4
PVOE
USI_THREE-
WIRE
USI_TWO-WIRE
DDE5
USI_TWO-WIRE
DDE4
PVOV
clk
I/O
DO
0
PTOE
––0USITC
DIEOE
PCINT7 PCIE0
PCINT6 PCIE0
(PCINT5 PCIE0)
+ USISIE
(PCINT4 PCIE0)
+ USISIE
DIEOV
1111
DI
PCINT7 INPUT
PCINT6 INPUT
DI/SDA INPUT
PCINT5 INPUT
USCKL/SCL
INPUT
PCINT4 INPUT
AIO
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