Diamond Systems RUBY-MM-1612 사용자 설명서
Copyright 2001 Diamond Systems Corp. Ruby-MM-1612 User Manual V1.1 P. 12
8. 82C55 DIGITAL I/O CHIP OPERATION
This is a short form description of the 82C55 digital I/O chip on the board. A full datasheet is included at
the back of this manual.
82C55 Register Map
Base + n, Dir, Function
D7
D6
D5
D4
D3
D2
D1
D0
4, R/W, Port A
A7
A6
A5
A4
A3
A2
A1
A0
5, R/W, Port B
B7
B6
B5
B4
B3
B2
B1
B0
6, R/W, Port C
C7
C6
C5
C4
C3
C2
C1
C0
7, W, Config Register
1
ModeC ModeA
DirA
DirCH
ModeB
DirB
DirCL
Configuration Register
The configuration register is programmed by writing to Base + 7 using the format below. Once you have
set the port directions with this register, you can read and write to the ports as desired.
set the port directions with this register, you can read and write to the ports as desired.
Bit No.
7
6
5
4
3
2
1
0
Name
1
ModeC ModeA
DirA
DirCH
ModeB
DirB
DirCL
Definitions:
1 Bit 7 must be set to 1 to indicate port mode set operation.
DirA Direction control for bits A7 – A0: 0 = output, 1 = input
DirB Direction control for bits B7 – B0: 0 = output, 1 = input
DirCL Direction control for bits C3 – C0: 0 = output, 1 = input
DirCH Direction control for bits C7 – C4: 0 = output, 1 = input
ModeA, ModeB, ModeC I/O Mode for each port, 0 or 1
Here is a list of common configuration register values (others are possible):
Configuration Byte
Hex Decimal Port A Port B Port C (both halves)
Hex Decimal Port A Port B Port C (both halves)
9B 155 Input Input Input (all ports input)
92 146 Input Input Output
99 153 Input Output Input
90 144 Input Output Output
8B 139 Output Input Input
82 130 Output Input Output
89 137 Output Output Input
80 128 Output Output Output (all ports output)
92 146 Input Input Output
99 153 Input Output Input
90 144 Input Output Output
8B 139 Output Input Input
82 130 Output Input Output
89 137 Output Output Input
80 128 Output Output Output (all ports output)