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(3)
System
control
circuit
(3-1)
Reference
clock generator
The
reference clock generator generates
timing
pulses
used
in
software generation of control
pulses for
PIONEER'S
standard
remote
control
(SEED, LD-700) and LD-1100
series
remote
control
units.
Although
two
reference clocks
are
required
(455kHz
for
LD-1100,
and
500kHz
for
PIONEER'S
standard
remote
control) for
the
different pulse
widths
in
standard
and LD-1100
remote
control
units,
the
LD-1100
is
capable
of
functioning
adequately
at
500kHz.
There-
fore,
the reference clock has
been
set
to
500kHz
in
a
circuit
consisting
of ceramic
resonator
(X
2)
and IC 37
(3/6, 4/6).
The
frequency
of the
500kHz
reference
clock
128
(see
Waveform
e
in Fig.
13-22)
and
is
sub-
sequently read
by
the
CPU
via bit
0 of
the
LCON
register.
REMCLKlUlh
- -
4
--
f
-
-
H
•
I
I
I
I
I
tssfs-
"u^rnrijnrTririr
-
m
m
mmm
m
mmv.
Fig.
13-22 Reference clock
generation
and
timing
(3-2)
Remote
control pulse generator
(1)
The
remote
control
code
is
written
(by
soft-
ware)
in bit
0
of
the
LCON
register
on
the
basis
of the timing
pulse generated
by
the
reference
clock
generator.
(2)
This latched
output
is
UREMO
which
serves
as
the source
signal
for
wired remote
control.
(3)
CREMO
is
generated
by
on/off switching of
the output obtained
by
dividing
REMCLK
by
12
based
on
UREMO.
(4)
CREMO
is
an
infra-red
LED
drive
signal
connected
by
coupler cord
for
infra-red
remote
control operation.
(Q9
is
a
driver transistor
which
is
no
longer necessary with
LD-1100
since direct
connection
to the control terminal
is
possible.)
(5)
EXTREMO
is
a
universal
wired remote
control
output.
(6)
LREMO
is
a wired
remote
control
sig
nal
output
for
an
LD-700
unit,
and
EXTREMI
is
a
wired remote
control input
for
remote
control
signals
passed to an
LD-700
unit
from
an
SD-26
unit.
(7)
Either_UREMO
or
EXTREMI
is
selected
by
LREMO
depending
on
the
SELCONT
status.
Fig.
13-23
Remote
control pulse generation
and
timing
Selection
Operation
(1)
When
SELCONT
is
+5V
•
UREMO
is
changed
to
L,
Q4
is
turned on,
Q5
is
turned
off,
and
LRE
MO
is
chan ged
to
H
via
D16
irrespective
of
the
EXTREMI
L/H
status.
•
UREMO
is
change
d
to H,
Q
4
is
turned
off,
Q5
is
turned
on,
and
LRE
MO
is
chan
ged
to
L
via
R53
irrespective
of the
EXTREMI
L/H
status.
(2)
When
SELCONT
is
0V
•
UREMO
is
changed
to
L
when no
remote
control
signal
is
sent,
resulting in
Q4
being
turned
off,
Q5
turned
off,
and
output of
EXTREMI
to
LREMI.
SELCONT
is
a
power
supply
voltage linked to
the
through
switch.
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