Port d, Port d data register – portd, Port d data direction register – ddrd – Rainbow Electronics AT90LS4433 User Manual
Page 80: Port d input pins address – pind
80
AT90S/LS4433
1042G–AVR–09/02
Port D
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors.
Three I/O memory address locations are allocated for Port D, one each for the Data
Register – PORTD, $12($32), Data Direction Register – DDRD, $11($31), and the Port
D Input Pins – PIND, $10($30). The Port D Input Pins address is read only, while the
Data Register and the Data Direction Register are read/write.
The Port D output buffers can sink 20 mA. As inputs, Port D pins that are externally
pulled low will source current if the pull-up resistors are activated.
Some Port D pins have alternate functions as shown in Table 26.
Port D Data Register – PORTD
Port D Data Direction Register
– DDRD
Port D Input Pins Address –
PIND
The Port D Input Pins address (PIND) is not a register; this address enables access to
the physical value on each Port D pin. When reading PORTD, the Port D Data Latch is
read, and when reading PIND, the logical values present on the pins are read.
Table 26. Port D Pin Alternate Functions
Port Pin
Alternate Function
PD0
RXD (UART Input Line)
PD1
TXD (UART Output Line)
PD2
INT0 (External Interrupt 0 Input)
PD3
INT1 (External Interrupt 1 Input)
PD4
T0 (Timer/Counter 0 External Counter Input)
PD5
T1 (Timer/Counter 1 External Counter Input)
PD6
AIN0 (Analog Comparator Positive Input)
PD7
AIN1 (Analog Comparator Negative Input)
Bit
7
6
5
4
3
2
1
0
$12 ($32)
PORTD7
PORTD6
PORTD5
PORTD4
PORTD3
PORTD2
PORTD1
PORTD0
PORTD
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
$11 ($31)
DDD7
DDD6
DDD5
DDD4
DDD3
DDD2
DDD1
DDD0
DDRD
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
$10 ($30)
PIND7
PIND6
PIND5
PIND4
PIND3
PIND2
PIND1
PIND0
PIND
Read/Write
R
R
R
R
R
R
R
R
Initial Value
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A