Page 18
Input Connections
Page 18
Blue Chip Technology Ltd.
01271014.doc
7
6
5
4
3
2
1
0
Base + 11
CONTROL
Bit 0 =
Port C (Lower)
0=Output,
1=Input.
Bit 1 =
Port B
0=Output,
1=Input.
Bit 2 =
Mode Selection
0=Mode 0,
1=Mode 1.
Bit 3 =
Port C (Upper)
0=Output,
1=Input.
Bit 4 =
Port A
0=Output,
1=Input.
Bits 5,6 =
Mode Selection
00=Mode 0,
01=Mode 1,
1X=Mode 2.
Bit 7 =
Mode Set Flag
0=Inactive,
1=Active.
See 4.3.1 for quick set-up guide.
A total of 24 I/O channel signals may be connected to the 8255 I/O device on
the ADC board providing 3 eight bit ports. Each signal is connected to one bit
within one of these port i.e.
Ports
Bit
Hex
Decimal
0
01
1
1
02
2
2
04
4
3
08
8
0
4
10
16
5
20
32
6
40
64
7
80
128
0
01
1
1
02
2
2
04
4
3
08
8
1
4
10
16
5
20
32
6
40
64
7
80
128