Port d data register – portd, Port d data direction register – ddrd, Port d input pins address – pind – Rainbow Electronics AT90S2313 User Manual
Page 56: Port d as general digital i/o, Alternate functions of port d, Table 20. dddn bits on port d pins
56
AT90S2313
0839I–AVR–06/02
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.
Port D as General Digital I/O
PDn, general I/O pin: The DDDn bit in the DDRD Register selects the direction of this
pin. If DDDn is set (one), PDn is configured as an output pin. If DDDn is cleared (zero),
PDn is configured as an input pin. If PORTDn is set (one) when configured as an input
pin, the MOS pull-up resistor is activated. To switch the pull-up resistor off, the PORTDn
has to be cleared (zero) or the pin has to be configured as an output pin. The Port D pins
are tri-stated when a reset condition becomes active, even if the clock is not active.
Note:
1. n: 6…0, pin number.
Alternate Functions of Port D
The alternate functions of Port D are:
• ICP – Port D, Bit 6
Timer/Counter1 Input Capture pin. See the Timer/Counter1 description for further
details.
• T1 – Port D, Bit 5
T1, Timer 1 Clock source. See the Timer description for further details.
• T0 – Port D, Bit 4
T0, Timer/Counter0 Clock source. See the Timer description for further details.
Bit
7
6
5
4
3
2
1
0
$12 ($32)
–
PORTD6
PORTD5
PORTD4
PORTD3
PORTD2
PORTD1
PORTD0
PORTD
Read/Write
R
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)
–
DDD6
DDD5
DDD4
DDD3
DDD2
DDD1
DDD0
DDRD
Read/Write
R
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)
–
PIND6
PIND5
PIND4
PIND3
PIND2
PIND1
PIND0
PIND
Read/Write
R
R
R
R
R
R
R
R
Initial value
0
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Table 20. DDDn Bits on Port D Pins
(1)
DDDn
PORTDn
I/O
Pull-up
Comment
0
0
Input
No
Tri-state (High-Z)
0
1
Input
Yes
PDn will source current if ext. pulled low
1
0
Output
No
Push-pull Zero Output
1
1
Output
No
Push-pull One Output