Z51F3220FNX Datasheet, PDF (74/312 Pages) Zilog, Inc. – Z8051 Series 8-Bit Microcontrollers

Z51F3220
Product Specification
9.7 P4 Port
9.7.1 P4 Port Description
P4 is 4-bit I/O port. P4 control registers consist of P4 data register (P4), P4 direction register (P4IO), P4 pull-up
resistor selection register (P4PU) and P4 open-drain selection register (P4OD). Refer to the port function
selection registers for the P4 function selection.
9.7.2 Register description for P4
P4 (P4 Data Register) : A0H
7
6
5
4
–
–
–
–
–
–
–
–
P4[3:0]
I/O Data
3
2
1
0
P43
P42
P41
P40
R/W
R/W
R/W
R/W
Initial value : 00H
P4IO (P4 Direction Register) : C9H
7
6
5
–
–
–
–
–
–
4
3
2
–
P43IO
P42IO
–
R/W
R/W
P4IO[3:0]
P4 Data I/O Direction
0
Input
1
Output
NOTE: SS0 function possible when input
1
P41IO
R/W
0
P40IO
R/W
Initial value : 00H
P4PU (P4 Pull-up Resistor Selection Register) : A3H
7
6
5
4
–
–
–
–
–
–
–
–
3
P43PU
R/W
2
P42PU
R/W
P4PU[3:0]
Configure Pull-up Resistor of P4 Port
0
Disable
1
Enable
1
P41PU
R/W
0
P40PU
R/W
Initial value : 00H
P4OD (P4 Open-drain Selection Register) : 94H
7
6
5
4
–
–
–
–
–
–
–
–
3
P43OD
R/W
2
P42OD
R/W
P4OD[3:0]
Configure Open-drain of P4 Port
0
Push-pull output
1
Open-drain output
1
P41OD
R/W
0
P40OD
R/W
Initial value : 00H
PS029902-0212
PRELIMINARY
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