Icom IC-756PROII Service Manual page 17

3-7-3 MAIN-CPU PORT ALLOCATIONS
(MAIN UNIT; IC3501)
Pin Port
number name
A0–A3,
6–9,
Address signal output ports for the
11–18, A4–A11,
LCD controller (IC3551).
20–26 A12–A18
Input port for the [KEY] jack.
29 SKYS
Low : During key down
RTKI Input port for the RTTY keying.
30
Power supply detection input port for
31 DPGI
the DSP-A board.
Input port for data signal from DSP-A
32 DSDR
board.
Input port for the [POWER] switch.
34 PWRK
Low : When the [POWER] is pushed.
DSKY Outputs CW/RTTY keying.
37
DB0–DB3, Data bus lines for the LCD controller
40–43,
45–52, DB4–DB11, (IC3551)
54–57 DB12–DB15 (IC3652–IC3654).
59 CTXD Output port for the CI-V signal.
61 CRXD Input port for the CI-V signal.
63 MCK Outputs clock signal.
64 MDAT Outputs data signal.
Input port for the [XVERT] detection
66 TRVI
signal.
Input port for transmit control signal
69 IKEY from the antenna tuner CPU (CTRL
board; IC5).
Outputs R8V regulator (Q601, Q602,
70 RXS D601) control signal.
Low : While receiving
Outputs T8V regulator (Q611, Q612,
71 TXS D611) control signal.
Low : While transmitting
72 ISTA Outputs antenna tuner start signal.
Outputs reset/inhibit signal to the sub-
CPU (DISPLAY board; IC401), DDS
73 DRES
ICs (PLL unit; IC101, IC401), antenna
tuner CPU (CTRL board; IC5), and etc.
Input port for unlock signal from the
UNLC
74
PLL unit.
Outputs strobe signals for the I/O
75 PSTB
expander IC (PLL unit; IC1).
Outputs strobe selection signals for
76 PSEL
the I/O expander (PLL unit; IC1).
Outputs control signal for the DDS cir-
77 CON2
cuits (PLL unit; IC101, IC401).
Description
and I/O expander
Pin Port
number name
CON1
78
(PDAT)
CON0
79
(PCK)
XTAL,
85, 86
EXTAL
96 LRES
97 LTXD
98 LRXD
101 TMD
SCPL
105
VOXL
106
107 AVXL
108 ASO0
109 ASO1
110 ASO2
111 STON
112 BEEP
115 SENI
116 PWRS
3 - 11
Description
Outputs data signal for the DDS cir-
cuits (PLL unit; IC101, IC401).
Outputs clock signal for the DDS cir-
cuits (PLL unit, IC101, IC401).
Input ports for the CPU system clock
oscillator (X3501; 19.6608 MHz).
Outputs reset/inhibit signal for the LCD
controller (IC3551), I/O expander
(IC3652–IC3654), and etc.
Outputs data signal for the sub-CPU
(DISPLAY board; IC401).
Input port for data signal from the sub-
CPU (DISPLAY board; IC401).
Outputs [TIMER] indicator control sig-
nal.
High: When the timer function is ON
Input port for the scope signal.
A/D input port for the VOX gain.
A/D input port for the anti-VOX level.
A/D input port via the analog switch
(IC3631) for the SML signal from the
S-meter amplifier circuit (IC101a), and
ALCL signal from the ALC meter
amplifier circuit (IC551a).
A/D input port via the analog switch
(IC3631) for the NSQO signal from the
level conveter (DSP-A board; IC2063),
for noise squelch operation, and FORL
signal from the power meter amplifier
circuit (IC571a).
A/D input port from the analog switch
(IC3631) for the FNTL signal from the
low-pass filter (DSP-A
IC2472a), for tone squelch operation,
and REFL signal from the SWR meter
amplifier circuit (IC571b).
Outputs CW side-tone signals.
Outputs beep audio signals.
Input port for connected microphone's
PTT switch and SEND signal from the
ACC jacks.
High: While PTT switch is pushed or
activated from an external unit.
Outputs control signal for the power
switching relay (PA unit; RL1) .
High: During power ON
board;