Port Allocations - Icom IC-F2721 Service Manual

4-6 PORT ALLOCATIONS

4-6-1 Main CPU (MAIN UNIT; IC23)
Pin Port
number name
I/O port for data signal to the D/A con-
1 DSDA
verter (IC30 pin 6).
Outputs strobe signals to the D/A con-
2 DAST
verter (IC8, pin 6).
Outputs serial data to the PLL IC (IC4,
10 SSO
pin 15) and D/A converter (IC8, pin 8).
Outputs clock signal to the PLL IC (IC4
11 SCK pin 14), D/A converter (IC8, pin 7),
etc.
Outputs strobe signals to the PLL IC
13 PLST
(IC4, pin 16).
Outputs control signal to the digital
/analog switch (IC42).
15 DASW
Low: While analog mode is se-
Outputs the T8V regulator circuit (Q34)
16 TXC control signal.
Low: During transmit.
Outputs the R8V regulator circuit
17 TMUT (Q30) control signal.
Low: During receive.
Outputs control signal for AF mute cir-
cuit (Q28, Q29).
18 AFON
High: While AF amplifier (IC38) is
Outputs wide/narrow switch (D2, D4)
control signal.
19 NWC
High: When narrow band is se-
Input port for serial data from the
20 DDSD
DTMF decoder IC (IC6, pin 9).
Outputs clock signals to the DTMF
21 DDAC
decoder IC (IC6, pin 10).
Input port for the AF mute signal from
32 RMUT the optional unit via J2.
Low: While RX audio is muted.
Input port for the microphone mute
signal from the optional unit via J2.
33 MMUT
Low: While microphone audio is
OPT1–
34–36 I/O ports for optional unit.
OPT3
Input port for the noise signal from the
37 NOIS
FM IF IC (IC9, pin 13).
Input port for the [ ] switch.
38 POSW
Low: While [ ] switch is pushed.
Input port for DTMF detection sig-
39 DDST nal from the DTMF decoder IC (IC6,
pin 11).
Input port for the remote power control
40 IGSW
signal from external connector, J7.
Outputs control signal for the power
41 PWON switch circuit (Q41, Q42).
Low: While power ON.
43 SENC Outputs single tone encoder signal.
Description
lected.
activated.
lected.
muted.
Pin Port
number name
44 BEEP
45 SDEC
46 CDEC
47 ULCK
48 BATV
49 LVIN
50 RSSI
51 TEMP
68 CLO
69 CLI
72 HORN
78 MTCK
79 NTXD
80 NRXD
88 DIM
CENC0–
89–91
CENC2
93 MTDT
94 MDIR
95 MDIO
96 MSCK
97 PMFM
98 ESDA
99 ESCL
4 - 6
Description
Outputs beep audio signals.
Input por t for single tone decode
signal from the base band IC (IC2,
pin 21).
Input port for CTCSS/DTCS signal
from the LPF (IC1, pin 7).
Input port for the PLL unlock signal.
Low: The PLL circuit is unlocked.
Input port for the connected battery
for the low battery detection.
Input port for the PLL lock voltage.
Input port for the S-meter signal from
the FM IF IC (IC12, pin 12).
Input port for the transceiver's internal
temperature detecting signal.
Outputs the data signal to the FRONT
CPU (FRONT UNIT; IC3).
Input port for the data signal from the
FRONT CPU (FRONT UNIT; IC3).
Outputs external device control signal.
High: When matched 5/2 tone sig-
nals are received.
Input port for transmitting MSK clock
signal from the base band IC (IC2,
pin 9).
Outputs NMEA data signals for the
connected unit via external connector
(J7).
Input port for NMEA data signals from
the connected unit via external con-
nector (J7).
Input port for the LCD backlight con-
trol signal from the external connector
(J8).
Low: W h i l e L C D b a c k l i g h t i s
dimmed.
Output the CTCSS/DTCS signals.
Outputs the MSK data to the base
band IC (IC2, pin 10).
Outputs serial data control signal to
the base band IC (IC2, pin 14 ).
I/O port for the serial data signals
f r o m / t o t h e b a s e b a n d I C ( I C 2 ,
pin 11).
Outputs clock signal for the base band
IC (IC2, pin 13).
Outputs the FM/PM switch (IC43,
pin 11) control signal.
High: While PM is selected.
I/O port for data signals from/to the
EEPROM (IC26, pin 5).
Outputs clock signal to the EEPROM
(IC26, pin 6).