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CP82C55A-5 参数 Datasheet PDF下载

CP82C55A-5图片预览
型号: CP82C55A-5
PDF下载: 下载PDF文件 查看货源
内容描述: CMOS可编程外设接口 [CMOS Programmable Peripheral Interface]
分类和应用:
文件页数/大小: 26 页 / 236 K
品牌: INTERSIL [ Intersil ]
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82C55A  
Ports A, B, and C  
register will contain 9Bh. During the execution of the system  
program, any of the other modes may be selected using a  
single output instruction. This allows a single 82C55A to  
service a variety of peripheral devices with a simple software  
maintenance routine. Any port programmed as an output  
port is initialized to all zeros when the control word is written.  
The 82C55A contains three 8-bit ports (A, B, and C). All can  
be configured to a wide variety of functional characteristics  
by the system software but each has its own special features  
or “personality” to further enhance the power and flexibility of  
the 82C55A.  
ADDRESS BUS  
CONTROL BUS  
DATA BUS  
Port A One 8-bit data output latch/buffer and one 8-bit data  
input latch. Both “pull-up” and “pull-down” bus-hold devices  
are present on Port A. See Figure 2A.  
Port B One 8-bit data input/output latch/buffer and one 8-bit  
data input buffer. See Figure 2B.  
Port C One 8-bit data output latch/buffer and one 8-bit data  
input buffer (no latch for input). This port can be divided into  
two 4-bit ports under the mode control. Each 4-bit port con-  
tains a 4-bit latch and it can be used for the control signal  
output and status signal inputs in conjunction with ports A  
and B. See Figure 2B.  
RD, WR  
D7-D0  
A0-A1  
CS  
82C55A  
C
MODE 0  
MODE 1  
B
8
A
8
I/O  
4
I/O  
4
I/O  
I/O  
PB7-PB0 PC3-PC0 PC7-PC4 PA7-PA0  
C
INPUT MODE  
MASTER  
RESET  
B
A
OR MODE  
CHANGE  
8
I/O  
8
I/O  
INTERNAL  
DATA IN  
EXTERNAL  
PORT A PIN  
PB7-PB0 CONTROL CONTROL PA7-PA0  
OR I/O OR I/O  
INTERNAL  
DATA OUT  
(LATCHED)  
MODE 2  
C
B
8
A
OUTPUT MODE  
BI-  
I/O  
FIGURE 2A. PORT A BUS-HOLD CONFIGURATION  
DIRECTIONAL  
V
CC  
PB7-PB0  
PA7-PA0  
RESET  
OR MODE  
CHANGE  
CONTROL  
P
FIGURE 3. BASIC MODE DEFINITIONS AND BUS INTERFACE  
CONTROL WORD  
D7 D6 D5 D4 D3 D2 D1 D0  
GROUP B  
INTERNAL  
DATA IN  
EXTERNAL  
PORT B, C  
PIN  
INTERNAL  
DATA OUT  
(LATCHED)  
PORT C (LOWER)  
1 = INPUT  
0 = OUTPUT  
OUTPUT MODE  
PORT B  
1 = INPUT  
0 = OUTPUT  
FIGURE 2B. PORT B AND C BUS-HOLD CONFIGURATION  
FIGURE 2. BUS-HOLD CONFIGURATION  
MODE SELECTION  
0 = MODE 0  
1 = MODE 1  
Operational Description  
GROUP A  
Mode Selection  
PORT C (UPPER)  
1 = INPUT  
There are three basic modes of operation than can be  
selected by the system software:  
Mode 0 - Basic Input/Output  
0 = OUTPUT  
PORT A  
1 = INPUT  
0 = OUTPUT  
Mode 1 - Strobed Input/Output  
Mode 2 - Bi-directional Bus  
MODE SELECTION  
00 = MODE 0  
When the reset input goes “high”, all ports will be set to the  
input mode with all 24 port lines held at a logic “one” level by  
internal bus hold devices. After the reset is removed, the  
82C55A can remain in the input mode with no additional ini-  
tialization required. This eliminates the need to pullup or pull-  
down resistors in all-CMOS designs. The control word  
01 = MODE 1  
1X = MODE 2  
MODE SET FLAG  
1 = ACTIVE  
FIGURE 4. MODE DEFINITION FORMAT  
4