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232
Port 3 Register (PORT3)
7
—
Undefined
—
6
—
Undefined
—
5
P35
—
*
R
4
P34
—
*
R
3
P33
—
*
R
0
P30
—
*
R
2
P32
—
*
R
1
P31
—
*
R
Bit
Initial value
R/W
:
:
:
Note:
*
Determined by state of pins P3
5
to P3
0
.
PORT3 is an 8-bit read-only register that shows the pin states. Writing of output data for the port 3
pins (P3
5
to P3
0
) must always be performed on P3DR.
Bits 7 and 6 are reserved; they return an undetermined value if read, and cannot be modified.
If a port 3 read is performed while P3DDR bits are set to 1, the P3DR values are read. If a port 3
read is performed while P3DDR bits are cleared to 0, the pin states are read.
After a power-on reset and in hardware standby mode, PORT3 contents are determined by the pin
states, as P3DDR and P3DR are initialized. PORT3 retains its prior state after a manual reset, and
in software standby mode.
Port 3 Open Drain Control Register (P3ODR)
7
—
Undefined
—
6
—
Undefined
—
5
P35ODR
0
R/W
4
P34ODR
0
R/W
3
P33ODR
0
R/W
0
P30ODR
0
R/W
2
P32ODR
0
R/W
1
P31ODR
0
R/W
Bit
Initial value
R/W
:
:
:
P3ODR is an 8-bit readable/writable register that controls the PMOS on/off status for each port 3
pin (P3
5
to P3
0
).
Bits 7 and 6 are reserved; they return an undetermined value if read, and cannot be modified.
Setting a P3ODR bit to 1 makes the corresponding port 3 pin an NMOS open-drain output pin,
while clearing the bit to 0 makes the pin a CMOS output pin.
P3ODR is initialized to H'00 (bits 5 to 0) by a power-on reset, and in hardware standby mode. It
retains its prior state after a manual reset, and in software standby mode.