
140
Port 6 Data Direction Register (P6DDR):
P6DDR is an 8-bit write-only register that can select
input or output for each pin in port 6.
Mode 1:
Pins P6
5
to P6
3
function as bus control output pins (
WR
,
RD
,
AS
). P6
0
functions as an
input/output pin. When P6
0
DDR is set to 1, P6
0
is an output pin, and when P6
0
DDR is 0, P6
0
is an
input pin. The P6
5
DDR to P6
3
DDR bit settings are ignored.
Modes 2 and 3:
Port 6 is a generic input/output port. A pin in port 6 becomes an output pin if the
corresponding P6DDR bit is set to 1, and an input pin if this bit is cleared to 0. Bits 7, 6, 2, and 1
are reserved.
P6DDR is a write-only register. Its value cannot be read. All bits return 1 when read.
P6DDR is initialized to H'80 by a reset and in hardware standby mode. In software standby mode it
retains its previous setting. If a P6DDR bit is set to 1, the corresponding pin maintains its output
state in software standby mode.
Port 6 Data Register (P6DR):
P6DR is an 8-bit readable/writable register that stores data for pins
P6
5
to P6
3
and P6
0
.
Bit
Initial value
Read/Write
7
—
1
—
6
—
0
W
5
P6 DDR
0
W
4
P6 DDR
0
W
3
P6 DDR
0
W
2
—
0
W
1
—
0
W
0
P6 DDR
0
W
Port 6 data direction 6 to 0
These bits select input or output for port 6 pins
Reserved bit
Bit
Initial value
Read/Write
7
—
1
—
6
—
0
R/W
5
P6
0
R/W
5
4
P6
0
R/W
4
3
P6
0
R/W
3
2
—
0
R/W
1
—
0
R/W
0
P6
0
R/W
0
Reserved bit
Port 6 data 5 to 3, 0
These bits store data for port 6 pins