ATmega48/88/168
• TXD/PCINT17 – Port D, Bit 1
TXD, Transmit Data (Data output pin for the USART). When the USART Transmitter is
enabled, this pin is configured as an output regardless of the value of DDD1.
PCINT17: Pin Change Interrupt source 17. The PD1 pin can serve as an external inter-
rupt source.
• RXD/PCINT16 – Port D, Bit 0
RXD, Receive Data (Data input pin for the USART). When the USART Receiver is
enabled this pin is configured as an input regardless of the value of DDD0. When the
USART forces this pin to be an input, the pull-up can still be controlled by the
PORTD0 bit.
PCINT16: Pin Change Interrupt source 16. The PD0 pin can serve as an external inter-
rupt source.
Table 40 and Table 41 relate the alternate functions of Port D to the overriding signals
shown in Figure 27 on page 67.
Table 40. Overriding Signals for Alternate Functions PD7..PD4
Signal PD7/AIN1
PD6/AIN0/
OC0A/PCINT22
PD5/T1/OC0B/
PCINT21
PD4/XCK/
T0/PCINT20
Name
PUOE
PUO
/PCINT23
0
0
0
0
0
0
0
0
0
0
0
0
DDOE
DDOV
PVOE
PVOV
0
0
0
0
0
0
OC0A ENABLE
OC0A
OC0B ENABLE
UMSEL
OC0B
XCK OUTPUT
PCINT20 • PCIE2
1
DIEOE PCINT23 • PCIE2
PCINT22 • PCIE2
1
PCINT21 • PCIE2
1
DIEOV
DI
1
PCINT23 INPUT
PCINT22 INPUT
PCINT21 INPUT
T1 INPUT
PCINT20 INPUT
XCK INPUT
T0 INPUT
AIO
AIN1 INPUT
AIN0 INPUT
–
–
77
2545D–AVR–07/04
ATMEL [ ATMEL ]
