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6-2.
Key Input Detection of Operation Buttons
The operation buttons on the unit and remote commander are each composed of switch matrix by combining with the
dividing resistor. As shown in Fig. 6-1. (b), when a operation button on the unit or a operation button on the remote control
unit is pressed, the voltage corresponding to the mode determined by the dividing resistor is input to Pin 8 [SET KEY] or Pin
7 [REM KEY] of the system controller (IC801) respectively. The system controller differentiates the mode according to this
input voltage, and sets the corresponding mode. As no power is supplied to the system controller in the sleep (standby) mode,
it will differentiate the mode after a button is pressed and power is supplied.
(1) When operating using the unit
Fig. 6-2. shows the connection between the operation buttons on the unit and the system controller (IC801) while Table 6-
1. shows the voltage input to the key input Pin 8 [SET KEY] of the system controller when a operation button is pressed.
When power supply to each part starts after wake-up, 2.8V (VC) from Pin #§ [VSTB] is supplied to R808 (47 kΩ) via the
switch inside the DC-DC converter (IC901). When a operation button is pressed in this state, a dividing voltage determined by
R808 (47 kΩ) and the resistor corresponding to that operation button, is input to Pin 8 of the system controller. A separate
line from the switch matrix is incorporated only for the PLAY button and voltage is input separately to Pin 5 [PLAY KEY]
so that the PLAY mode is set even when the button has been pressed instantaneously.
2.8[V]
VC
DC-DC CONVERTER
10
36
PLAY
R803
R808
470k
47k
STOP
R809 2.2k
FF
R810 4.7k
REW
R811 6.8k
VOL+
R812 15k
VOL-
R813 33k
P-MODE
Fig. 6-2 Key Input Circuit of Operation Buttons of Unit
IC901
IC801
SYSTEM CONTROLLER
PLAY KEY
5
SET KEY
8
Table 6-1. Key Input Voltage During Operations of
Unit (Reference Values)
Operation Buttons of Unit
STOP
FF
REW
VOL +
VOL –
P-MODE
When nothing is pressed
— 28 —
Pin 8 of IC801
0V
0.15V
0.4V
0.6V
1.0V
1.5V
2.8V
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