Hitachi RAS-18SX8 Manuel De Maintenance page 131

4. Remote control reception circuit
Remote control
reception input
Microcomputer
[Typical communication waveform]
Remote control reception input
^6
(pin
Beep (reception tone)
・An infrared signal from the remote control unit is converted to an electrical signal by the remote
control light-receiving unit (IC821) and is received by the microcomputer. Data is transmitted as
digital data 0 and 1 by changing the interval of the basic pulses at about 420μs.
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12V
R821
R640
66
IC601
0V
of microcomputer)
Enlarged reception waveform
5V
Approx.
420μs.
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Remote control
Q821
light-receiving unit
R822
Ⅰ C821
C821 C822
VDD
R823
VOUT
GND
Fig. 4-1
Approx. 400 ms.
Fig. 4-2
– 164 –