AT90S/LS4434 and AT90S/LS8535
81
•
OC1B – Port D, Bit 4
OC1B, Output compare matchB output: The PD4 pin can serve as an external output for the Timer/Counter1 output com-
pareB. The pin has to be configured as an output (DDD4 set [one]) to serve this function. See the timer description on how
to enable this function. The OC1B pin is also the output pin for the PWM mode timer function.
•
INT1 – Port D, Bit 3
INT1, External Interrupt source 1: The PD3 pin can serve as an external interrupt source to the MCU. See the interrupt
description for further details and how to enable the source.
•
INT0 – Port D, Bit 2
INT0, External Interrupt source 0: The PD2 pin can serve as an external interrupt source to the MCU. See the interrupt
description for further details and how to enable the source.
•
TXD – Port D, Bit 1
Transmit Data (data output pin for the UART). When the UART Transmitter is enabled, this pin is configured as an output,
regardless of the value of DDD1.
•
RXD – Port D, Bit 0
Receive Data (data input pin for the UART). When the UART Receiver is enabled, this pin is configured as an input, regard-
less of the value of DDD0. When the UART forces this pin to be an input, a logical “1” in PORTD0 will turn on the internal
pull-up.
Port D Schematics
Note that all port pins are synchronized. The synchronization latches are, however, not shown in the figures.
Figure 61.
Port D Schematic Diagram (Pin PD0)
DA
T
A
BUS
D
D
Q
Q
RESET
RESET
C
C
WD
WP
RD
MOS
PULL-
UP
PD0
RXD
RXEN
WP:
WD:
RL:
RP:
RD:
RXD:
RXEN:
WRITE PORTD
WRITE DDRD
READ PORTD LATCH
READ PORTD PIN
READ DDRD
UART RECEIVE DATA
UART RECEIVE ENABLE
DDD0
PORTD0
RL
RP