The Port D pins with alternate functions
are shown in the table below:
Table 1. Port D Pins Alternate Functions
| Port Pin |
Alternate Function |
| PD7 |
AIN1 (Analog Comparator Negative Input)
PCINT23 (Pin Change Interrupt 23)
|
| PD6 |
AIN0 (Analog Comparator Positive Input)
OC0A (Timer/Counter0 Output Compare Match A Output)
PCINT22 (Pin Change Interrupt 22)
|
| PD5 |
T1 (Timer/Counter 1 External Counter Input)
OC0B (Timer/Counter0 Output Compare Match B Output)
PCINT21 (Pin Change Interrupt 21)
|
| PD4 |
XCK0 (USART0 External Clock Input/Output)
T0 (Timer/Counter 0 External Counter Input)
PCINT20 (Pin Change Interrupt 20)
|
| PD3 |
INT1 (External Interrupt 1 Input)
OC2B (Timer/Counter2 Output Compare Match B Output)
PCINT19 (Pin Change Interrupt 19)
|
| PD2 |
INT0 (External Interrupt 0 Input)
OC3B (Timer/Counter3 Output Compare Match B Output)
OC4B (Timer/Counter4 Output Compare Match B Output)
PCINT18 (Pin Change Interrupt 18)
|
| PD1 |
TXD0 (USART0 Output Pin)
OC4A (Timer/Counter4 Output Compare Match A Output)
PCINT17 (Pin Change Interrupt 17)
|
| PD0 |
RXD1 (USART1 Input Pin)
OC3A (Timer/Counter3 Output Compare Match A Output)
PCINT16 (Pin Change Interrupt 16)
|
The alternate pin configuration is as follows:
- AIN1/OC2B/PCINT23 – Port D, Bit 7
- AIN1: Analog Comparator1 Negative Input. Configure the port pin as input with the
internal pull-up switched off to avoid the digital port function from interfering
with the function of the Analog Comparator.
- PCINT23: Pin Change Interrupt source 23. The PD7 pin can serve as an external
interrupt source.
- AIN0/OC0A/PCINT22 – Port D, Bit 6
- AIN0: Analog Comparator0 Positive Input. Configure the port pin as input with the
internal pull-up switched off to avoid the digital port function from interfering
with the function of the Analog Comparator.
- OC0A: Output Compare Match output. The PD6 pin can serve as an external output
for the Timer/Counter0 Compare Match A. The PD6 pin has to be configured as an
output (DDD6 set (one)) to serve this function. The OC0A pin is also the output
pin for the PWM mode timer function.
- PCINT22: Pin Change Interrupt source 22. The PD6 pin can serve as an external
interrupt source.
- T1/OC0B/PCINT21 – Port D, Bit 5
- T1: Timer/Counter1 counter source.
- OC0B: Output Compare Match output. The PD5 pin can serve as an external output
for the Timer/Counter0 Compare Match B. The PD5 pin has to be configured as an
output (DDD5 set (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.
- XCK0/T0/PCINT20 – Port D, Bit 4
- 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/OC3B/PCINT18 – Port D, Bit 2
- INT0: External Interrupt source 0.
The PD2 pin can serve as an external interrupt source.
- OC3B: Output Compare Match output: The PD2 pin can serve as an external output
for the Timer/Counter3 Compare Match B. The PD2 pin has to be configured as an
output (DDD2 set (one)) to serve this function. The OC3B pin is also the output
pin for the PWM mode timer function.
- OC4B: Output Compare Match output: The PD2 pin can serve as an external output
for the Timer/Counter4 Compare Match B. The PD2 pin has to be configured as an
output (DDD2 set (one)) to serve this function. The OC4B pin is also the output
pin for the PWM mode timer function.
- PCINT18: Pin Change Interrupt
source 18. The PD2 pin can serve as an external interrupt source.
- TXD0/PCINT17 – Port D, Bit 1
- TXD0: Transmit Data (Data output pin for the USART0). When the USART0 Transmitter
is enabled, this pin is configured as an output regardless of the value of
DDD1.
- OC4A: Output Compare Match output: The PD1 pin can serve as an external output
for the Timer/Counter4 Compare Match A. The PD1 pin has to be configured as an
output (DDD1 set (one)) to serve this function. The OC4A pin is also the output
pin for the PWM mode timer function.
- PCINT17: Pin Change Interrupt source 17. The PD1 pin can serve as an external
interrupt source.
- RXD0/OC3A/PCINT16 – Port D, Bit 0
- RXD0: 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 DDD0. When the USART0 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.
- OC3A: Output Compare Match output:
The PD0 pin can serve as an external output for the Timer/Counter3 Compare Match
A. The PD0 pin has to be configured as an output (DDD0 set (one)) to serve this
function. The OC3A pin is also the output pin for the PWM mode timer
function.
The tables below relate the alternate
functions of Port D to the overriding signals shown in Figure 1.
Table 2. Overriding Signals for Alternate Functions PD7...PD4
| Signal
Name |
PD7/AIN1
/PCINT23 |
PD6/AIN0/
OC0A/PCINT22 |
PD5/T1/OC0B/
PCINT21 |
PD4/XCK0/
T0/PCINT20 |
| PUOE |
0 |
0 |
0 |
0 |
| PUO |
0 |
0 |
0 |
0 |
| DDOE |
0 |
0 |
0 |
0 |
| DDOV |
0 |
0 |
0 |
0 |
| PVOE |
0 |
OC0A ENABLE |
OC0B ENABLE |
UMSEL |
| PVOV |
0 |
OC0A |
OC0B |
XCK0
OUTPUT |
| DIEOE |
PCINT23 • PCIE2 |
PCINT22 • PCIE2 |
PCINT21 • PCIE2 |
PCINT20 • PCIE2 |
| DIEOV |
1 |
1 |
1 |
1 |
| DI |
PCINT23 INPUT |
PCINT22 INPUT |
PCINT21
INPUT
/T1 INPUT |
PCINT20
INPUT
/XCK0 INPUT
/T0 INPUT |
| AIO |
AIN1 INPUT |
AIN0 INPUT |
– |
– |
Table 3. Overriding Signals for Alternate Functions in PD3...PD0
| Signal
Name |
PD3/OC2B/INT1/
PCINT19 |
PD2/OC3B/OC4B/INT0/
PCINT18 |
PD1/TXD0/OC4A/
PCINT17 |
PD0/OC3A/RXD0/
PCINT16 |
| PUOE |
0 |
0 |
TXEN0 |
RXEN0 |
| PUO |
0 |
0 |
0 |
PORTD0 •
PUD |
| DDOE |
0 |
0 |
TXEN0 |
RXEN0 |
| DDOV |
0 |
0 |
1 |
0 |
| PVOE |
OC2B ENABLE |
OC3B/OC4B
ENABLE |
TXEN0 / OC4A
ENABLE |
OC3A
ENABLE |
| PVOV |
OC2B |
OC3B/OC4B |
TXD0 /
OC4A |
OC3A |
| DIEOE |
INT1 ENABLE + PCINT19 • PCIE2 |
INT0 ENABLE +
PCINT18 • PCIE2 |
PCINT17 • PCIE2 |
PCINT16 • PCIE2 |
| DIEOV |
1 |
1 |
1 |
1 |
| DI |
PCINT19
INPUT
/INT1 INPUT |
PCINT18
INPUT
/INT0 INPUT |
PCINT17 INPUT |
PCINT16
INPUT
/RXD0 |
| AIO |
– |
– |
– |
– |