Basic HTML Version
SWITCH MATRIX
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SWITCH MATRIX CIRCUIT
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SWITCH
C_OSED I
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0"
The microprocessor is constantly strobing the column side of the switch, When point -An on the column circuit
toggles low. the column side is active, When a switch closes, the row side of the circuit activates, The .+" input to
the
lM339
drops below
+5V.
therefore, its output is low. Corresponding row and column switches must be low at the
same time tor the switch
10
be considered closed
by
the microprocessor. When the switch opens. the •• " input to the
lM339
is above
.5V.
its output is high and the row is inactive.
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