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MD82C55B 参数 Datasheet PDF下载

MD82C55B图片预览
型号: MD82C55B
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: HARRIS [ HARRIS CORPORATION ]
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82C55A  
Reading Port C Status (Figures 15 and 16)  
Applications of the 82C55A  
In Mode 0, Port C transfers data to or from the peripheral  
device. When the 82C55A is programmed to function in  
Modes 1 or 2, Port C generates or accepts “hand shaking”  
signals with the peripheral device. Reading the contents of  
Port C allows the programmer to test or verify the “status” of  
each peripheral device and change the program flow  
accordingly.  
The 82C55A is a very powerful tool for interfacing peripheral  
equipment to the microcomputer system. It represents the  
optimum use of available pins and flexible enough to inter-  
face almost any I/O device without the need for additional  
external logic.  
Each peripheral device in a microcomputer system usually  
has a “service routine” associated with it. The routine  
manages the software interface between the device and the  
CPU. The functional definition of the 82C55A is programmed  
by the I/O service routine and becomes an extension of the  
system software. By examining the I/O devices interface  
characteristics for both data transfer and timing, and  
matching this information to the examples and tables in the  
detailed operational description, a control word can easily be  
developed to initialize the 82C55A to exactly “fit” the  
application. Figures 18 through 24 present a few examples  
of typical applications of the 82C55A.  
There is not special instruction to read the status information  
from Port C. A normal read operation of Port C is executed to  
perform this function.  
INTERRUPT  
ENABLE FLAG  
ALTERNATE PORT C  
PIN SIGNAL (MODE)  
POSITION  
INTE B  
INTE A2  
INTE A1  
PC2  
ACKB (Output Mode 1)  
or STBB (Input Mode 1)  
PC4  
PC6  
STBA (Input Mode 1 or  
Mode 2)  
ACKA (Output Mode 1 or  
Mode 2)  
FIGURE 17. INTERRUPT ENABLE FLAGS IN MODES 1 AND 2  
INTERRUPT  
REQUEST  
PC3 PA0  
PA1  
HIGH SPEED  
PRINTER  
PA2  
PA3  
PA4  
PA5  
PA6  
PA7  
MODE 1  
(OUTPUT)  
HAMMER  
RELAYS  
PC7  
PC6  
PC5  
DATA READY  
ACK  
PAPER FEED  
FORWARD/REV.  
PC4  
82C55A  
PB0  
PB1  
PB2  
PB3  
PB4  
PB5  
PB6  
PB7  
PAPER FEED  
FORWARD/REV.  
RIBBON  
MODE 1  
(OUTPUT)  
CARRIAGE SEN.  
PC1  
PC2  
DATA READY  
ACK  
PC0  
INTERRUPT  
REQUEST  
CONTROL LOGIC  
AND DRIVERS  
FIGURE 18. PRINTER INTERFACE  
14  
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