Port Allocations - Icom IC-T7H Service Manual

4-5 PORT ALLOCATIONS

4-5-1 CPU (LOGIC UNIT; IC1)
Pin Port
number name
Input port for remote control signal
2 REMOTE from an optional HM-75A microphone
via the [EXT MIC] jack.
Input port for detected S-meter signals
3 SD
from the IC101 (pin 12) on the 2F unit.
Input port for received CTCSS tone
4 CTCIN
signals.
Output port for +3C regulator circuit
5 PCON control signals.
"HIGH" : Power ON.
6 PLST Output PLL strobe signals.
Output port for clock signals to PLL
7 PLCK/ECK
and EEPROM ICs.
DATA bus line for PLL.
• Outputs PLL DATA when PLL is
locked.
8 PDA/UL • When PLL is unlocked, PLL IC
releases the port being pulled up,
therefore, the CPU receives "HIGH"
level signal.
9 CTCSS Output port for CTCSS tone signals.
Output port for:
• Beep audio signals while receiving.
10 DTMF • DTMF signals or 1,750 Hz tone sig-
nal while transmitting.
(According to versions)
Input pulse signals for noise squelch
12 NOISE
from the IC101 (pin 13) on the 2F unit.
Input port for the [LOCK] switch.
17 LOCK
"LOW" : [LOCK] switch is ON.
Inputs up/down signals from the
21 DIUD
[DIAL] control.
22 DICK Input port for dial clock signals.
Input port for the [POWER] switch.
23 POWER
"Low" : [POWER] switch is pushed.
24 CONT Outputs LCD contrast control signals.
28–31 KR3–KR0 Input port for key matrix.
Input port for the PTT control circuit.
32 PTT
"HIGH" : When transmitting.
Input port for reset circuit (LOGIC unit;
33 RESET
IC3, pin 1).
Outputs control signals to the power
supply of the CTCSS band-pass filter
39 CFC
(LOGIC unit; Q45).
"LOW" : Activates the BPF.
DATA bus line for the EEPROM
40 ESIO
(LOGIC unit; IC15) data signals.
Outputs [BUSY] LED control signals.
41 BLED
"HIGH" : The [BUSY] LED lights.
Description
Pin Port
number name
42 LIGHT
43 MICC
44 MM/RM
46 TXSEL
47 HVCO
48 LVCO
49 SHIFT
55 AFON
56 H/L
4 - 5
Description
Outputs LCD backlight control signals.
"High" : The backlight lights.
Output port for the microphone ampli-
fier (LOGIC unit; IC12).
"LOW" : Activates the mic. amplifier.
Output a mute signal.
[MM] : Microphone mute for DTMF
or 1,750 Hz tone while
transmitting.
[RM] : Audio mute for squelch cir-
cuit while receiving.
"HIGH" : To mute one of above.
Outputs transmit frequency band con-
trol signals.
"HIGH" : UHF band.
"LOW" : VHF band.
Output port for the UHF band VCO
(DUAL-VCO board; Q301, Q302 and
D301) control signals.
"HIGH" : Activates the UHF-VCO.
Output port for the VHF band VCO
(DUAL-VCO board; Q304, Q305 and
D303) control signals.
"HIGH" : Activates the VHF-VCO.
Output port for SHIFT signals to the
shift switches (1F unit; Q354, Q854).
"HIGH" : Transmit on VHF.
"LOW" : Transmit on UHF.
Outputs control signals to the AF reg-
ulator circuit (2F unit; Q151,Q152).
"HIGH" : Activates the AF amplifier.
Output port for the TX output power
(HIGH or LOW) select signals.
"LOW" : HIGH power is selected.