Icom IC-F51 SEG1, Sck, Mdio, Msck, Scst, Plst, Esda, Scat, Exsf, Exsm, Exoe, Beep, Mtdt, Mtck

4-6-2 MAIN CPU (FRONT unit; IC401)

Pin	Port	Description
number	name
1–11,	SEG23–
	SEG13,
13,	SEG12,	Output segment data to the LCD dis-
		play.
15–25,	SEG11–
	SEG1
		Outputs serial data to the PLL IC
26	SO	(MAIN unit; IC6, pin 8) and D/A con-
		vertor (MAIN unit; IC6, pin 8).
		Outputs serial clock signal to the PLL
27	SCK	IC (MAIN unit; IC4, pin 9), D/A conver-
		tor (MAIN unit; IC6, pin 7), etc.
		I/O port for the serial data signals
28	MDIO	from/to the base band IC (MAIN unit;
		IC10, pin 11).
29	MSCK	Outputs clock signal to the base band
		IC (MAIN unit; IC10, pin 13).
30	SCST	Outputs strobe signals to the scram-
		bler IC (MAIN unit; IC14, pin 11).
31	PLST	Outputs strobe signals to the PLL IC
		(MAIN unit; IC4, pin 11).
32	ESDA	I/O port for data signals from/to the
		EEPROM (IC409, pin 5).
33	ESCL	Outputs clock signal to the EEPROM
		(IC409, pin 6).
		• Outputs power down control signal to
		the scrambler IC (MAIN unit; IC14,
34	SCAT	pin 12).
		• Input port for the detection signal
		whether the scrambler unit is
		installed or not.
35	EXSF	Outputs strobe signals to the expander
		IC (IC410, pin 2).
36	EXSM	Outputs strobe signals to the expander
		IC (MAIN unit; IC12, pin 1).
		Outputs the enable signal to the
37	EXOE	expander ICs (IC410, pin 15 and MAIN
		unit; IC12, pin 15).
38	BEEP	Outputs beep audio signals.
		Outputs MSK data for transmitting to
39	MTDT	the base band IC (MAIN unit; IC10, pin
		10).
		Input port for the transmitting MSK
40	MTCK	clock signal from the base band IC
		(MAIN unit; IC10, pin 9).
41	NOIS	Input port for the noise signal from the
		FM IF IC (MAIN unit; IC1, pin 13).
		Input port for single tone decode signal
43	SDEC	from the base band IC (MAIN unit;
		IC10, pin 21).
		Input port for CTCSS/DTCS signal
44	CDEC	from the amplifier (MAIN unit; IC5, pin
		8).

Pin	Port	Description
number	name
		Input port for the PTT switch detection
45	PTT	signal.
		Low: While the PTT switch is
		pushed.
46	KR1	Input ports for the key return A/D sig-
47	KR0	nals.
48	BATV	Input port for the detect signal for con-
		necting battery pack’s voltage.
49	LVIN	Input port for the PLL lock voltage.
50	RSSI	Input port for the S-meter signal from
		the FM IF IC (MAIN unit; IC1, pin 12).
51	TEMP	Input port for the transceiver’s internal
		temperature detecting signal.
52	OPTV	Input port for the optional microphone
		determine signal.
55	ULCK	Input port for the PLL unlock signal.
		Low: The PLL circuit is unlocked.
		Outputs serial data control signal to
71	MDIR	the base band IC (MAIN unit; IC10, pin
		14)
72–75	SENC3–	Output single tone encoder signal.
	SENC0
76	CLO	Outputs the cloning data signal.
77	CLI	Input port for the cloning data signal.
		Input port for the receiving MSK detec-
78	MRDF	tion signal from the base band IC
		(MAIN unit; IC10, pin 12)
79–81	CENC2–	Output the CTCSS/DTCS signals.
	CENC0
		• Outputs strobe signals to the D/A
82	DAST	convertor (IC6, pin 6).
		• Input port for the connecting battery
		type detect signal.
88–91	COM4–	Output common signal to the LCD dis-
	COM1	play.

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