Icom IC-F620 Service Manual page 11

CPU (IC20)—continued
Pin Port
number name
Input port for MIC mute signal from the
33 MMUT
optional board via J1.
OPT1– I/O ports for the optional board control
34–36
signals.
OPT3
NOIS signal input port from the FM IF
37 NOIS IC (MAIN unit; IC1) for noise squelch
operation.
Input for the POWER switch.
38 POSW
Low : While POWER switch is pushed.
Input port for DTMF detection signal
39 DDST
from the DTMF decoder (IC19).
Remote power control signal input port
40 IGSW
from the external connector (J8).
Outputs control signal for the power
41 PWON
switching circuit (Q24, Q23) via D28.
43 SENC Outputs single tone signal.
44 BEEP Outputs beep audio signals.
Single tone signal input port for decod-
45 SDEC
ing from the LPF (IC21c).
CTCSS/DTCS signals input port for
46 CDEC
decoding from the LPF (IC5).
Input port for the PLL unlock signal
47 ULCK
from the PLL IC (IC4).
Input port for the overvoltage detection
48 BATV
from the connected power supply.
Input port for the PLL lock voltage.
49 LVIN
Input port for receiving signal strength
50 RSSI
level detection.
Input port for the transceiver's internal
51 TEMP
temperature.
Input port for the AF volume control
(FRONT unit; R12).
52 AFVI
High : [VOL] is maximum clockwise.
Input port for the PTT switch from the
55 EPTT external connector (J6).
Low : External PTT switch is ON.
Input port for the reset signal.
59 RES
Output port for the cloning signal.
68 CLO
Input port for the cloning signal.
69 CLI
Outputs CPU clock shift signal.
70 CSFT
Outputs cut-off frequency control signal
71 DUSE to the
CTCSS/DTCS switching.
Input port for the connected modem
74 XCTS
unit via external connector (J9).
Output port for the connected modem
75 XRTS
unit via external connector (J9).
Description
low-pass filter (IC5) for
CPU (IC20)—continued
Pin Port
number name
76 XTXD
77 XRXD
79 NTXD
80 NRXD
81 CIRQ
88 DIM
CENC2–
89–91
CENC0
92 AFCL
94, AMSK,
95 ADIN
96 APST
97 PMFM
98 ESDA
99 ESCL
100 PA
4 - 5
Description
Input port for serial data signals from
the connected MAP27 unit via external
connector (J9).
Outputs serial data signals for the con-
nected MAP27 unit via external con-
nector (J9).
Output serial data signals (data format
is in accordance with NMEA0183) for
the connected unit via external connec-
tor (J8).
Input port for serial data signals (data
format is in accordance
NMEA0183) from the connected unit
via external connector (J8).
Input port for interruption signal from
the optional board via J1
Input port for the LCD backlight control
signal from the external connector (J6).
Output ports for the CTCSS/ DTCS sig-
nals.
Outputs reset signal for the compander
IC (IC14).
Output control signals for the compan-
der IC (IC14).
Outputs strobe signals to the compan-
der IC (IC14).
Outputs control signal for the MSK
PM/FM switching circuit (IC15).
I/O port for the data signals from the
EEPROM (IC23).
Outputs clock signal for the EEPROM
(IC23).
Outputs MIC audio select signal for the
analog switch (IC25).
Low : While "Public-address" function
is ON.
with