2545M–AVR–09/07

ATmega48/88/168

13.3.3 Alternate Functions of Port D

The Port D pins with alternate functions are shown in Table 13-9.

The alternate pin configuration is as follows:

• AIN1/OC2B/PCINT23 – Port D, Bit 7

AIN1, Analog Comparator 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 Comparator 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.

Table 13-9. 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

XCK (USART 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)

PCINT18 (Pin Change Interrupt 18)

PD1

TXD (USART Output Pin)

PCINT17 (Pin Change Interrupt 17)

PD0

RXD (USART Input Pin)

PCINT16 (Pin Change Interrupt 16)

2545M–AVR–09/07

ATmega48/88/168

• 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.

• 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/Counter0 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.

Table 13-10 and Table 13-11 relate the alternate functions of Port D to the overriding signals

shown in Figure 13-5 on page 77.

2545M–AVR–09/07

ATmega48/88/168

Table 13-10. Overriding Signals for Alternate Functions PD7..PD4

Signal

Name

PD7/AIN1

/PCINT23

PD6/AIN0/

OC0A/PCINT22

PD5/T1/OC0B/

PCINT21

PD4/XCK/

T0/PCINT20

PUOE0000

PUO0000

DDOE 0 0 0 0

DDOV 0 0 0 0

PVOE 0 OC0A ENABLE OC0B ENABLE UMSEL

PVOV 0 OC0A OC0B XCK OUTPUT

DIEOE PCINT23 • PCIE2 PCINT22 • PCIE2 PCINT21 • PCIE2 PCINT20 • PCIE2

DIEOV1111

DI PCINT23 INPUT PCINT22 INPUT

PCINT21 INPUT

T1 INPUT

PCINT20 INPUT

XCK INPUT

T0 INPUT

AIO AIN1 INPUT AIN0 INPUT – –

Table 13-11. Overriding Signals for Alternate Functions in PD3..PD0

Signal

Name

PD3/OC2B/INT1/

PCINT19

PD2/INT0/

PCINT18

PD1/TXD/

PCINT17

PD0/RXD/

PCINT16

PUOE 0 0 TXEN RXEN

PUO000PORTD0 • PUD

DDOE 0 0 TXEN RXEN

DDOV 0 0 1 0

PVOE OC2B ENABLE 0 TXEN 0

PVOV OC2B 0 TXD 0

DIEOE

INT1 ENABLE +

PCINT19 • PCIE2

INT0 ENABLE +

PCINT18 • PCIE1

PCINT17 • PCIE2 PCINT16 • PCIE2

DIEOV1111

PCINT19 INPUT

INT1 INPUT

PCINT18 INPUT

INT0 INPUT

PCINT17 INPUT

PCINT16 INPUT

RXD

AIO––––

Part #	ATMEGA48-20AU
Description	MCU 8BIT ATMEGA RISC 4KB FLASH 3.3V/5V 32TQFP - Trays
Category	IC
Availability	Out of Stock
Qty	0

ATMEGA48-20AU

Related Items

Technical Document