82C55A_15 Ver la hoja de datos (PDF) - Intersil
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82C55A_15 Datasheet PDF : 30 Pages
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82C55A
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.
There is not a 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
POSITION
ALTERNATE PORT C
PIN SIGNAL (MODE)
INTE B
PC2
ACKB (Output Mode 1)
or STBB (Input Mode 1)
INTE A2
PC4
STBA (Input Mode 1 or Mode
2)
INTE A1
PC6
ACKA (Output Mode 1 or
Mode 2)
FIGURE 17. INTERRUPT ENABLE FLAGS IN MODES 1 AND 2
Applications of the 82C55A
The 82C55A is a very powerful tool for interfacing peripheral
equipment to the microcomputer system. It represents the
optimum use of available pins and is flexible enough to
interface 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.
INTERRUPT
REQUEST
PC3 PA0
PA1
PA2
PA3
PA4
MODE 1
(OUTPUT)
PA5
PA6
PA7
PC7
PC6
PC5
PC4
82C55A
PB0
PB1
PB2
PB3
PB4
MODE 1 PB5
(OUTPUT) PB6
PB7
PC1
PC2
PC0
DATA READY
ACK
PAPER FEED
FORWARD/REV.
DATA READY
ACK
HIGH SPEED
PRINTER
HAMMER
RELAYS
PAPER FEED
FORWARD/REV.
RIBBON
CARRIAGE SEN.
INTERRUPT
REQUEST
CONTROL LOGIC
AND DRIVERS
FIGURE 18. PRINTER INTERFACE
FN2969 Rev 11.00
Dec 8, 2015
Page 15 of 30
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