144
in P4DDR is set to 1, if port 4 is read the value of the corresponding P4DR bit is returned. When a
bit in P4DDR is cleared to 0, if port 4 is read the corresponding pin logic level is read.
Bit
Initial value
Read/Write
7
P4
0
R/W
Port 4 data 7 to 0
These bits store data for port 4 pins
7
6
P4
0
R/W
6
5
P4
0
R/W
5
4
P4
0
R/W
4
3
P4
0
R/W
3
2
P4
0
R/W
2
1
P4
0
R/W
1
0
P4
0
R/W
0
P4DR is initialized to H'00 by a reset and in hardware standby mode. In software standby mode it
retains its previous setting.
Port 4 Input Pull-Up MOS Control Register (P4PCR): P4PCR is an 8-bit readable/writable
register that controls the MOS input pull-up transistors in port 4.
Bit
Initial value
Read/Write
7
P4 PCR
0
R/W
Port 4 input pull-up MOS control 7 to 0
These bits control input pull-up transistors built into port 4
7
6
P4 PCR
0
R/W
6
5
P4 PCR
0
R/W
5
4
P4 PCR
0
R/W
4
3
P4 PCR
0
R/W
3
2
P4 PCR
0
R/W
2
1
P4 PCR
0
R/W
1
0
P4 PCR
0
R/W
0
In 8-bit bus mode in modes 1 to 4 (expanded modes), when a P4DDR bit is cleared to 0 (selecting
generic input), if the corresponding P4PCR bit is set to 1, the input pull-up transistor is turned on.
P4PCR is initialized to H'00 by a reset and in hardware standby mode. In software standby mode it
retains its previous setting.
Table 7.3 summarizes the states of the input pull-up MOS in each operating mode.
Table 7.3
Input Pull-Up Transistor States (Port 4)
Mode
Reset
Hardware
Standby Mode
Software
Standby Mode
Other Modes
1 to 4
8-bit bus mode
Off
Off
On/off
On/off
16-bit bus mode
Off
Off
Legend
Off:
The input pull-up transistor is always off.
On/off: The input pull-up transistor is on if P4PCR = 1 and P4DDR = 0. Otherwise, it is off.
Summary of Contents for H8/3008
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