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8051 Microcontroller (Internals, Instructions, Programming and Interfacing)
book

8051 Microcontroller (Internals, Instructions, Programming and Interfacing)

by Subrata Ghosal
May 2024
Intermediate to advanced content levelIntermediate to advanced
503 pages
17h 2m
English
Pearson India
Content preview from 8051 Microcontroller (Internals, Instructions, Programming and Interfacing)
260
INTERFACING: KEYBOARDS
Above description may be apparently a complex and longer one. However, the basic objective is to maintain
only one column low at a time and keep on incrementing the key counter before testing each key input.
Whenever any input is found low, the value within the key counter is to be copied immediately to the return
code register. Softwarewise it is easy to implement. We will develop the complete subroutine after introducing
the debouncing part within it.
Figure 18.10 Schematic of interfacing 64 keys in 8 × 8 matrix
RETURN LINES
SCAN LINES
8051
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
OUTPUT PORT INPUT ...
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Publisher Resources

ISBN: 9781282655034Publisher Website