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Reler to Figures C,D, and E as you read the lollowing.
Pulse A advances against Pulse B when the tuning knob turns c1ockwise; the opposite takes place when the tuning
knob turns counterclockwise.
The CPU checks the status of Pulse B at the lalling edge of Pulse A and judges the direction of the tuning knob rota-
tion. Il Pulse B is high, the knob is turned clockwlse lor higher Irequency;
if
it is lew, the knob is turned counterclock-
wise lor lower Irequency.
The CPU also counts the number of pulses to determine the magnitude of the Irequency/chaqnnel change. One
pulse represents one notch rotation of the tuning knob.
Note: The width of the pulse is irrelevant to the operation. It only shows how last the knob is turned.
0501
Pulse A
To ICSD1 Pin 13. 17
+---~
Pulse B
+-_ _-;
ToICSD1 Pin 6
r:
P~seA
SV
1
Figure C
r
Pulse B
sv
1
r
PulseA
5V
1
-
-
-
-
-
Figure D
- -
-
-
T--
Pulse B 5V
1
Figure E
- 6 -
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