Cpu Port Allocations (Logic Unit) - Icom IC-2SET Service Manual

4-5-3 1750
Hz
TONE CALL
CIRCUITS
(LOGIC UNIT)
Only the
IC-2SET
is
equipped
with this
function.
When
the [PIT] switch
is
quickly
pushed
2 times or
when
the [PTT] switch
is
pushed with
the [LIGHT] switch,
pin
79
of
the
CPU (TONE OUT)
outputs a
1750
Hz
tone
signal.
R15
adjusts the
1750 Hz tone deviation.
The
signal
is
aiso output to
the
AF UNIT
via
R12.
4-5-4
SUBAUDIBLE
TONE ENCODER
CIRCUIT
This function
can be activated only
when
an optional
UT-50
TONE SOUELCH UNIT
or
UT-51
PROGRAMMABLE
TONE ENCODER
UNIT
is
installed.
A
tone
signal
is
applied
to
the splatter
filter
circuit
on
the
MIC UNIT
via
the
TONE
signal
line.
RIO on
the
UT-50 and R5 on
the UT-51 adjust the subaudible tone
deviation.
4-5-5
DTMF ENCODER
CIRCUIT
(LOGIC
UNIT)
This function
can be
activated only
when
the matrix
KEYS1->KEYI1
is
OPEN,
(an
optional
UT-49
DTMF
DECODER
UNIT
is
installed.)
Pins
70 and
71
of the
CPU (TONEC/TONER)
output
a
DTMF
code
signal.
R16
adjusts the
DTMF
code
signal
deviation.
The
signal
is
also output to
the
AF UNIT
via
R17.
4-5-6
CPU RESET CIRCUIT (LOGIC
UNIT)
103
detects -F5 voltage.
When
the
-F5 voltage
line
becomes
5
V,
103 turns
INTO
"HIGH" and
the
CPU
(101)
restarts
operation.
The
CPU
is
reset
when
IC1 pin
76
becomes "HIGH."
The
AND
gate
10 (104)
outputs a
reset
signal
when
both
input
terminals are
"HIGH."
One
terminal
is
"HIGH" when
the
[MONIj
switch
is
pushed and the
other (INTO
line) is
"HIGH" when
the
power
is
turned
ON.
RESET CIRCUIT
+
5
4-5-7
TRANSMIT/RECEIVE INDICATOR
CIRCUIT (LOGIC UNIT)
The transmit/receive
indicator
(DS4) uses a 2-input
LED
and
lights
up
in
red or
green.
The
indicator
lights
up
in
red
as the transmit indicator
while transmitting using the
T-F5
voltage.
The
indicator
lights
up
in
green as the
busy
indicator
while the
squelch
opens
using
CPU
pin
78
output via
the
inverter
(02).
4-5-8
CLOCK OSCILLATOR CIRCUIT
(LOGIC
UNIT)
IC1 oscillates
the
798.642 kHz
CPU
system clock
signal
using XI.
101 oscillates
the
32.768
kHz
clock signal for
the
built-in
clock using X2.
4-6
CPU PORT ALLOCATIONS
(LOGIC
UNIT)
•
INPUT
PORT
PORT
NUMBER
PIN
NUMBER
DESCRIPTION
D4
[PTT]
1
Inputs
a signal
on
the
PTT
line.
This port
becomes
"LOW"
when
the
PTT
switch
is
pushed.
D5
[SIN]
2 Inputs
S-meter-compared
signal
from IC2b to indicate the
CPU
counting
ievel to
the S-indicator
in
the function display.
DIO
[UL]
7
Detects a
PLL
unlock signal.
When
the
signal
is
"HIGH," the
PLL
is
uniocked.
D12,
D13
[DIAL
UP/DN]
9,
10 input port for
the
up/down
signai of
the tuning controi.
R10-R13
[KEYIO-
KEYI3]
19—22
These are input ports for
the
initiai
and
key matrices.
R20-R23
[KEYRO-
KEYR3]
23-26
These
are input ports for
the
keyboard and
DTMF
code from
the
UT-49.
R30
[BUSY]
27 Detects a squeich signai.
The
signai
is
"HiGH" when
the squeich
opens.
R31
[OPT]
28 Input port for
an optional
unit.
This port
becomes "HIGH" when
the
tone squelch opens. (UT-50)
This port
becomes
"LOW" when
the UT-51
is
installed.
R32
[INTO]
29 Detects a signal for
the
standby
mode
of
the
CPU. The
CPU
enters
the
standby
mode when
the port
becomes "LOW."
R33
[INTI]
30
The
CPU
decodes received
DTMF
code
when
this port
becomes
"LOW."
4
—
5
Fig. 5