Datasheet

Port Pin Alternate Function
PD2 INT2/RXD1
(1)
(External Interrupt2 Input or UART1 Receive Pin)
PD1 INT1/SDA
(1)
(External Interrupt1 Input or TWI Serial Data)
PD0 INT0/SCL
(1)
(External Interrupt0 Input or TWI Serial Clock)
Note: 1. XCK1, TXD1, RXD1, SDA, and SCL not applicable in ATmega103 compatibility mode.
The alternate pin configuration is as follows:
• T2 – Port D, Bit 7
T2, Timer/Counter2 counter source.
• T1 – Port D, Bit 6
T1, Timer/Counter1 counter source.
• XCK1 – Port D, Bit 5
XCK1, USART1 External clock. The Data Direction Register (DDD5) controls whether the clock is output
(DDD5 set) or input (DDD5 cleared). The XCK1 pin is active only when the USART1 operates in
Synchronous mode.
• ICP1 – Port D, Bit 4
ICP1 – Input Capture Pin1: The PD4 pin can act as an Input Capture Pin for Timer/Counter1.
• INT3/TXD1 – Port D, Bit 3
INT3, External Interrupt source 3: The PD3 pin can serve as an external interrupt source to the MCU.
TXD1, Transmit Data (Data output pin for the USART1). When the USART1 Transmitter is enabled, this
pin is configured as an output regardless of the value of DDD3.
• INT2/RXD1 – Port D, Bit 2
INT2, External Interrupt source 2. The PD2 pin can serve as an External Interrupt source to the MCU.
RXD1, Receive Data (Data input pin for the USART1). When the USART1 receiver is enabled this pin is
configured as an input regardless of the value of DDD2. When the USART forces this pin to be an input,
the pull-up can still be controlled by the PORTD2 bit.
•INT1/SDA – Port D, Bit 1
INT1, External Interrupt source 1. The PD1 pin can serve as an external interrupt source to the MCU.
SDA, Two-wire Serial Interface Data: When the TWEN bit in TWCR is set (one) to enable the Two-wire
Serial Interface, pin PD1 is disconnected from the port and becomes the Serial Data I/O pin for the Two-
wire Serial Interface. In this mode, there is a spike filter on the pin to suppress spikes shorter than 50 ns
on the input signal, and the pin is driven by an open drain driver with slew-rate limitation.
• INT0/SCL – Port D, Bit 0
INT0, External Interrupt source 0. The PD0 pin can serve as an external interrupt source to the MCU.
SCL, Two-wire Serial Interface Clock: When the TWEN bit in TWCR is set (one) to enable the Two-wire
Serial Interface, pin PD0 is disconnected from the port and becomes the Serial Clock I/O pin for the Two-
wire Serial Interface. In this mode, there is a spike filter on the pin to suppress spikes shorter than 50 ns
on the input signal, and the pin is driven by an open drain driver with slew-rate limitation.
Atmel ATmega64A [DATASHEET]
Atmel-8160E-ATmega64A_Datasheet_Complete-09/2015
104