XC2200 Derivatives
System Units (Vol. 1 of 2)
Parallel Ports
User’s Manual
7-12
V2.1, 2008-08
Parallel Ports, V1.6D6
7.2.4
Port Input Register
The port input register contains the values currently read at the input pins, also if a port
line is assigned as output.
Pn_IN (n=0-11)
Port n Input Register
SFR (FF80
H
+2*n)
Reset Value: 0000
H
1)
P15_IN
Port 15 Input Register
SFR (FF9E
H
)
Reset Value: 0000
H
1)
Px bits for non implemented I/O lines are always read as 0.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
P15 P14 P13 P12 P11 P10
P9
P8
P7
P6
P5
P4
P3
P2
P1
P0
rh
rh
rh
rh
rh
rh
rh
rh
rh
rh
rh
rh
rh
rh
rh
rh
Field
Bits
Type Description
Px
(x = 0-15)
x
rh
Port Input Bit x
This bit indicates the level at the input pin of port Pn,
pin x.
0
The input level of Pn.x is 0.
1
The input level of Pn.x is 1.