ATmega8U2/16U2/32U2
TXD1, USART1 Transmit Data : When the USART1 Transmitter is enabled, this pin is config-
ured as an ouput regardless of DDRD3.
• INT2/AIN1/RXD1, Bit 2
INT2, External Interrupt source 2: The PD2 pin can serve as an external interrupt source to the
MCU.
AIN1, Analog Comparator Negative input. This pin is directly connected to the negative input of
the Analog Comparator.
RXD1, USART1 Receive Data : When the USART1 Receiver is enabled, this pin is configured
as an input regardless of DDRD2. When the USART forces this pin to be an input, the pull-up
can still be controlled by the PORTD2 bit.
• INT1/AIN0, Bit 1
INT1, External Interrupt source 1: The PD1 pin can serve as an external interrupt source to the
MCU.
AIN0, Analog Comparator Positive input. This pin is directly connected to the positive input of
the Analog Comparator.
• INT0/OC0B, Bit 0
INT0, External Interrupt source 0: The PD0 pin can serve as an external interrupt source to the
MCU.
OC0B, Output Compare Match B output: The PD0 pin can serve as an external output for the
Timer/Counter0 Output Compare. The pin has to be configured as an output (DDD0 set “one”) to
serve this function. The OC0B pin is also the output pin for the PWM mode timer function.
Table 12-10 and Table 12-11 relates the alternate functions of Port D to the overriding signals
shown in Figure 12-5 on page 72.
80
7799D–AVR–11/10
ATMEL [ ATMEL ]
