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Port B Register (PORTB)
Bit
:
7
PB7
Initial value :
—*
R/W
:
R
Note: * Determined by state of pins PB7 to PB0.
PORTB is an 8-bit read-only register that shows the pin states. It cannot be written to. Writing of
output data for the port B pins (PB7 to PB0) must always be performed on PBDR.
If a port B read is performed while PBDDR bits are set to 1, the PBDR values are read. If a port B
read is performed while PBDDR bits are cleared to 0, the pin states are read.
Reading a pin being used as an LCD driver returns an undefined value.
After a reset and in hardware standby mode, PORTB contents are determined by the pin states, as
PBDDR and PBDR are initialized. PORTB retains its prior state in software standby mode.
Port B MOS Pull-Up Control Register (PBPCR)
Bit
:
7
PB7PCR PB6PCR PB5PCR PB4PCR PB3PCR PB2PCR PB1PCR PB0PCR
Initial value :
0
R/W
:
R/W
PBPCR is an 8-bit readable/writable register that controls the MOS input pull-up function
incorporated into port B on an individual bit basis.
In modes 4 to 6, if a pin is in the input state in accordance with the settings in the LCD driver's
LPCR and in DDR, setting the corresponding PBPCR bit to 1 turns on the MOS input pull-up for
that pin.
In mode 7, if a pin is in the input state in accordance with the settings in the DDR, setting the
corresponding PBPCR bit to 1 turns on the MOS input pull-up for that pin.
PBPCR is initialized to H'00 by a reset, and in hardware standby mode. It retains its prior state in
software standby mode.
6
5
PB6
PB5
PB4
—*
—*
R
R
6
5
0
0
R/W
R/W
R/W
4
3
PB3
PB2
—*
—*
—*
R
R
4
3
0
0
R/W
R/W
2
1
0
PB1
PB0
—*
—*
R
R
R
2
1
0
0
0
0
R/W
R/W
263
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