Datasheet

61
ATmega8A [DATASHEET]
8159E–AVR–02/2013
13.3.4 Alternate Functions of Port D
The Port D pins with alternate functions are shown in Table 13-8.
The alternate pin configuration is as follows:
• AIN1 – 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.
• AIN0 – 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.
• T1 – Port D, Bit 5
T1, Timer/Counter1 counter source.
• XCK/T0 – Port D, Bit 4
XCK, USART external clock.
T0, Timer/Counter0 counter source.
• INT1 – Port D, Bit 3
INT1, External Interrupt source 1: The PD3 pin can serve as an external interrupt source.
• INT0 – Port D, Bit 2
INT0, External Interrupt source 0: The PD2 pin can serve as an external interrupt source.
• TXD – Port D, Bit 1
TXD, Transmit Data (Data output pin for the USART). When the USART Transmitter is enabled, this pin is config-
ured as an output regardless of the value of DDD1.
• RXD – 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.
Table 13-8. Port D Pins Alternate Functions
Port Pin Alternate Function
PD7 AIN1 (Analog Comparator Negative Input)
PD6 AIN0 (Analog Comparator Positive Input)
PD5 T1 (Timer/Counter 1 External Counter Input)
PD4
XCK (USART External Clock Input/Output)
T0 (Timer/Counter 0 External Counter Input)
PD3 INT1 (External Interrupt 1 Input)
PD2 INT0 (External Interrupt 0 Input)
PD1 TXD (USART Output Pin)
PD0 RXD (USART Input Pin)