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Port 3 Register (PORT3)
Bit
:
7
P37
Initial value :
—*
R/W
:
R
Note: * Determined by the state of pins P37 to P30.
PORT3 is an 8-bit read-dedicated register, which reflects the state of pins. Write is disenabled.
Always carry out writing off output data of port 3 pins (P37 to P30) to P3DR without fail.
When P3DDR is set to 1, if port 3 is read, the values of P3DR are read. When P3DDR is cleared to
0, if port 3 is read, the states of pins are read out.
P3DDR and P3DR are initialized by a power-on reset and in hardware standby mode, so PORT3 is
determined by the state of the pins. The previous state is maintained by a manual reset and in
software standby mode.
Port 3 Open Drain Control Register (P3ODR)
Bit
:
7
P37DDR
Initial value :
0
R/W
:
W
P3ODR is an 8-bit readable/writable register, which controls the on/off of port 3 pins (P37 to P30).
By setting P3ODR to 1, the port 3 pins become an open drain out, and when cleared to 0 they
become CMOS output.
P3ODR is initialized to H'00 by a power-on reset and in hardware standby mode. The previous
state is maintained by a manual reset and in software standby mode.
6
5
P36
P35
—*
—*
R
R
6
5
P36DDR
P35DDR
0
0
W
W
4
3
P34
P33
—*
—*
R
R
4
3
P34DDR
P33DDR
0
0
W
W
2
1
P32
P31
—*
—*
R
R
2
1
P32DDR
P31DDR
0
0
W
W
0
P30
—*
R
0
P30DDR
0
W
349
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