Port d data register – portd, Port d data direction register – ddrd, Port d input pins address – pind – Rainbow Electronics AT90LS8535 User Manual
Page 87: Port d as general digital i/o, Alternate functions of port d, Table 34. dddn bits on port d pins
87
AT90S/LS8535
1041H–11/01
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 PDn is set (one) when configured as an input pin, the
MOS pull-up resistor is activated. To switch the pull-up resistor off, the PDn has to be
cleared (zero) or the pin has to be configured as an output pin.The port pins are tri-
stated when a reset condition becomes active, even if the clock is not running.
Note:
n: 7,6…0, pin number.
Alternate Functions of Port D
• OC2 – Port D, Bit 7
OC2, Timer/Counter2 output compare match output: The PD7 pin can serve as an
external output for the Timer/Counter2 output compare. The pin has to be configured as
an output (DDD7 set [one]) to serve this function. See the timer description on how to
enable this function. The OC2 pin is also the output pin for the PWM mode timer
function.
• ICP – Port D, Bit 6
IC P – I np u t C ap t ure P i n: Th e P D 6 p i n c a n act as a n i n p ut c ap t ure p i n f or
Timer/Counter1. The pin has to be configured as an input (DDD6 cleared [zero]) to
serve this function. See the timer description on how to enable this function.
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
Table 34. DDDn Bits on Port D Pins
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