Port c data register – portc, Port c data direction register – ddrc, Port c input pins address – pinc – Rainbow Electronics AT90LS4433 User Manual
Page 78: Port c as general digital i/o, Table 25. ddcn effects on port c pins
78
AT90S/LS4433
1042G–AVR–09/02
Port C Data Register – PORTC
Port C Data Direction Register
– DDRC
Port C Input Pins Address –
PINC
The Port C Input Pins address (PINC) is not a register; this address enables access to
the physical value on each Port C pin. When reading PORTC, the Port C Data Latch is
read, and when reading PINC, the logical values present on the pins are read.
Port C as General Digital I/O
All six pins in Port C have equal functionality when used as digital I/O pins.
PCn, general I/O pin: The DDCn bit in the DDRC Register selects the direction of this
pin. If DDCn is set (one), PCn is configured as an output pin. If DDCn is cleared (zero),
PCn is configured as an input pin. If PORTCn is set (one) when the pin is configured as
an input pin, the MOS pull-up resistor is activated. To switch the pull-up resistor off,
PORTCn 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:
1. n: 5..0, pin number
Bit
7
6
5
4
3
2
1
0
$15 ($35)
–
–
PORTC5
PORTC4
PORTC3
PORTC2
PORTC1
PORTC0
PORTC
Read/Write
R
R
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
$14 ($34)
–
–
DDC5
DDC4
DDC3
DDC2
DDC1
DDC0
DDRC
Read/Write
R
R
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
$13 ($33)
–
–
PINC5
PINC4
PINC3
PINC2
PINC1
PINC0
PINC
Read/Write
R
R
R
R
R
R
R
R
Initial Value
0
0
N/A
N/A
N/A
N/A
N/A
N/A
Table 25. DDCn Effects on Port C Pins
DDCn
PORTCn
I/O
Pull-up
Comment
0
0
Input
No
Tri-state (high-Z)
0
1
Input
Yes
PCn will source current if ext. pulled low.
1
0
Output
No
Push-pull Zero Output
1
1
Output
No
Push-pull One Output