Icom IC-M88 Service Manual page 11

4-5 PORT ALLOCATIONS
4-5-1 CPU (LOGIC UNIT; IC661)
Pin Port
number name
1 BEEP Outputs beep audio signals.
Outputs strobe signals for the scram-
2 VSSTB
bler IC (MAIN unit; IC381, pin 10).
Outputs
3 EXSTB
expander IC (MAIN unit; IC341, pin 1).
Outputs strobe signals for the D/A
4 DASTB
converter (MAIN unit; IC251, pin 6).
Outputs strobe signals for the PLL IC
5 PLSTB
(MAIN unit; IC1, pin 11).
6 ERXDI Input port for cloning signals.
7 ETXDO
Outputs cloning signals.
Outputs serial data for PLL, scrambler
10 SDATA
ICs, etc.
Outputs serial clock for PLL, scram-
11 SCLK
bler ICs, etc.
Outputs clock signal for the EEPROM
12 ESCK
(IC591, pin 6).
I/O port for EEPROM data signal
13 ESDA
(IC591, pin 5).
Outputs CPU clock shift signal.
17 CSIFT
High : While clock is shifted.
27 WDECV
Input port for the WX tone detection.
Input port for the transceiver's internal
28 WETIN
inundation detection.
Input port for the external terminal
29 EXTSV
connecting detection.
Input port for the battery voltage
30 BATTV
detection.
Input port for transmit RF level detec-
31 TDETV
tion.
32 NOISV
Input port for noise level detection.
Input port for RSSI voltage level
33 RSSIV
detection.
Input port for VCO lock voltage level
34 LOINV
detection.
Input port for the transceiver's internal
35 TEMPV
temperature detection.
36 CDECV Input port for CTCSS/DTCS detection.
38 ATIS
Outputs ATIS wave form.
COM0–
46–48
Output LCD common signals
COM2
SEG0–
51–70 Output LCD segment signals.
SEG19
75 CONT1
Output LCD contrast control signals.
76 CONT2
77 LEDS1
Output LCD and key's back light dim-
78 LEDS2 mer control signal.
Description
strobe signals for the
Pin Port
number name
79 STXMS
80 MICMS
81 ISPMS
82 LDTFS
83 W/NS
84 AFMS
85 AFVS
86 M5VS
87 S5VS
88 V5VS
89 R5VS
90 T5VS
98 CENC1
99 CENC2
100 CENC3
102 PTTIN
103 EPTTIN
104 BTYPE
109 SQL
110 UP
4 - 4
Description
Outputs scrambler mute signal for the
AF mute circuit (IC481, pin 3).
Low : While scrambler is muting.
Outputs mic mute signal for the AF
mute circuit (IC481, pin 7).
Low : While the microphone is mut-
ing.
Outputs the internal speaker control
signal.
High : While the speaker is muting.
Outputs DTCS's low-pass filter cut-off
frequency control signal.
Outputs Wide/Narrow control signal.
high : While Narrow is selected.
Outputs the AF mute circuit control
signal.
High : The AF mute circuit is ON.
Outputs AF amplifier's power supply
control signal.
High : The AF amplifier is ON.
Outputs M5V power supply control
signal.
Low : The common 5V is supplied.
Outputs S5V power supply control sig-
nal.
Low : The common 5V is supplied.
Outputs V5V power supply control sig-
nal.
Low : The common 5V is supplied.
Outputs R5V power supply control sig-
nal.
Low : While receiving.
Outputs T5V power supply control sig-
nal.
Low : While transmitting.
Output DTCS/CTCSS wave form.
Input port for [PTT] swtich detection.
High : While [PTT] switch is pushed.
Input port for HM-138 (optional speak-
er-microphone)'s [PTT] swtich detec-
tion.
Low : While HM-138's [PTT] switch
is pushed.
Input port for the connecting battery
type detection.
Low : While using alkaline cells.
Input port for the [SQL] key.
Low : While [SQL] key is pushed.
Input port for the [UP] key.
Low : While [UP] key is pushed.