Datasheet

(one)) to serve this function. The OC0B pin is also the output pin for the PWM mode timer
function.
– PCINT21: Pin Change Interrupt source 21. The PD5 pin can serve as an external interrupt
source.
• XCK/T0/PCINT20 – Port D, Bit 4
– XCK: USART external clock.
– T0: Timer/Counter0 counter source.
– PCINT20: Pin Change Interrupt source 20. The PD4 pin can serve as an external interrupt
source.
• INT1/OC2B/PCINT19 – Port D, Bit 3
– INT1: External Interrupt source 1. The PD3 pin can serve as an external interrupt source.
– OC2B: Output Compare Match output: The PD3 pin can serve as an external output for the
Timer/Counter2 Compare Match B. The PD3 pin has to be configured as an output (DDD3 set
(one)) to serve this function. The OC2B pin is also the output pin for the PWM mode timer
function.
– PCINT19: Pin Change Interrupt source 19. The PD3 pin can serve as an external interrupt
source.
• INT0/PCINT18 – Port D, Bit 2
– INT0: External Interrupt source 0. The PD2 pin can serve as an external interrupt source.
– PCINT18: Pin Change Interrupt source 18. The PD2 pin can serve as an external interrupt
source.
• 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 interrupt
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 interrupt
source.
The tables below relate the alternate functions of Port D to the overriding signals shown in Figure 18-5.
Table 18-10. Overriding Signals for Alternate Functions PD7...PD4
Signal
Name
PD7/AIN1
/PCINT23
PD6/AIN0/
OC0A/PCINT22
PD5/T1/OC0B/
PCINT21
PD4/XCK/
T0/PCINT20
PUOE 0 0 0 0
PUOV 0 0 0 0
DDOE 0 0 0 0
DDOV 0 0 0 0
PVOE 0 OC0A ENABLE OC0B ENABLE UMSEL
ATmega48PA/88PA/168PA
I/O-Ports
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40002011A-page 123