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SEQ-555ES
ICsog,509 (MULTIPLEXER)
This is an input selection IC, and determines the pin
to be selected
by combinations
of signals of pins
@, @ and @.
The truth table is given below.
© | @ | @ | @ onPin
INH
A
B
C
Ee
Sg 2) 6.
Sse
-@
ol)
ee
ee
1
Be}
te.
SS
Pate.
|e
L | L|H
| H |] 3
L}|H]|LI]
LI
4
L | AH]L]
Hi]
5
L | H/|
Hj]
Li]
6
L
H
H
H
7
DC
voltage
of the frequency selected at the multi-
plexer is sent to the A/D converter via the logarithmic
amp.
ICsos (MICROCOMPUTER
D)
The main functions of this microcomputer
are A/D
converter (ICs97)
control
and LCD
display control.
It operates independently
of microcomputer
B, and
microcomputer
B receives A/D converted data from
microcomputer D only during acoustic compensation.
Multiplexer
control signals (@, ©~@®)
are output
from
microcomputer
D and
the
frequency
to be
selected is determined.
Pin Functions
Pin @ : Strobe signal for LCD display.
Pins @, @):
LCD display data output pin.
Pin @3:
Reset signal input pin.
Pin @:
A/D converter END signal input pin.
Pin @:
Data input from A/D converter.
Pin
:
Chip enable output to A/D converter.
Pin
:
Start signal output to A/D converter.
ICso,
(MICROCOMPUTER
B)
This microcomputer
controls the entire system and
interacts with microcomputers A, C and D to control
them.
Pin
Functions
Pins @~@) control the 8 ASP IC's.
The upper 3 bits of each ASP IC correspond to the
chip select pin (CS), and each pin is set as follows.
000
001
010
orl
100
ICios
ICxo9
ICiio
Gri
Irie
CX7976
CX7976
CX7976
CX7976
OX7976
101
110
110
ICyos
ICasi
IC352
CX7978
CX7977
CX7977
Pin @:
Output pin for ASP clock signal.
Pin @:
ASP data signal output pin.
Pin @:
ASP strobe signal output pin.
Pins
@~@
control
which
IC is to be selected.
ICiog~1i2
form
the
equalizer
volume
circuit, and
by controlling
these
IC's, each
frequency
is con-
trolled UP or DOWN.
ICio3 performs level UP/DOWN
and operates as a 2dB step volume.
1C351,352 are input selection IC's.
Pins
@)~@)
are analog signal switching signals, and
are as follows:
Pin ©):
PINK
NOISE/LINE
H:
PINK NOISE
switching
Pin @):
MIC/LINE
H:
MIC
Pin @:
+6dB/+12dB
H:
+6dB
Pin
:
MUTING
H:
MUTING ON
Pins
() and © are low except during acoustic com-
pensation.
(Pin @ can be switched between H/L.)
Pin @) inputs the interrupt signal output by micro-
computer A before it sends data to microcomputer B.
When
interrupt
is received, an interrupt permission
signal is output from pin
@
to microcomputer A.
Pins @) and @) output REC OUT MUTING circuit
control signals.
When high, REC
MUTING
turns ON.
MUTING
is turned on so that TAPE,
signal is not
output to REC OUT, and TAPE, signal is not output
to REC OUT,.
Pin
@
outputs an interrupt signal before data is sent
to microcomputer C.
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