Front panel IC-706

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Cable pinout

Pin  	Signal 	Color         Description
1 	LRXD 	Yellow        Data transfer from front panel to the radio.
2 	LTXD 	Black         Data transfer from radio to the front panel.
3 	8V 	Blue          DC power (8V) to the front panel.
4 	AF 	Red           Output audio to headphone jacket.
5 	GND 	Shield        Data, power, output audio and power control ground.
6 	MIC 	White         Microphone input.
7 	MICE 	Green shield  Microphone ground.
8 	PWK 	White         Power control (switch ON button). Active in low.

Switch on

Power switch on panel turns PWK signal to low (ground). Radio turns on supply voltage on pin 8V.


Both sides communicate at 19200 Baud, 8 bits, no parity, 1 stop bit. Protocol is similar to CI-V control. AFAIK it is not published so next informations are taked by reverse-engineering.

  • Packet starts with Preamble code (0xfe).
  • Second byte is probably Command number.
  • Folows Data area with variable length.
  • Last byte is End of message code (0xfd).
  • Data bytes 0xfd 0xfe and 0xff are sent with escape prefix:
    • 0xfd sent as 0xff 0x0d
    • 0xfe sent as 0xff 0x0e
    • 0xff sent as 0xff 0x0f

Commands Panel to Radio

0x01 PTT

Send mike's PTT state (bit 0) and whether the headphone jack is plugged in (bit 1).


FE 00 00 FD    ; PTT OFF (RX), headphone jack out
FE 00 01 FD    ; PTT ON  (TX), headphone jack out
FE 00 02 FD    ; PTT OFF (RX), headphone jack in
FE 00 03 FD    ; PTT ON  (TX), headphone jack in

0x01 Buttons 1

Send state of button group 1. Button state is sent as bitmask in one data byte.

Bit  Mask   Button
0    0x01   F-1
1    0x02   MENU
2    0x04   TUNER/CALL
3    0x08   P.AMP/ATT
4    0x10   RIT/SUB
5    0x20   
6    0x40   DN (mike)
7    0x80   UP (mike)


FE 01 04 FD    ; button TUNER/CALL pressed
FE 01 00 FD    ; button TUNER/CALL released

0x02 Buttons 2

Send state of button group 2.

Bit  Mask   Button
0    0x01   Band down
1    0x02   Band up
2    0x04   TS
3    0x08   MODE
4    0x10   LOCK
5    0x20   DISPLAY
6    0x40   F-3
7    0x80   F-2

0x03 Tune

Main tune knob state. In 3rd byte is state 0x00 to 0xff. It is incremented by clockwise turn and decremented by counterclockwise turn;

0x05 Volume

Volume knob state. In 3rd byte is volume value 0x00 (mute) to 0xff (max volume).

0x06 RF/SQL

Same as previous command but for RF/SQL knob.

0x07 M-CH

Same as Volume command but for M-CH knob.

0x08 SHIFT

Same as Volume command but for RF/SQL knob.

0x0b Keepalive

Keepalive packet sent from panel to radio about every 100 ms. When no packet is received by radio in about 200 ms, it switches itself off. To provide reliable work over IP networks, this packet should be emulated.


FE 0B 00 FD

0xf0, 0xf1 Handshake

Probably some handshake sent between units during powerup.


R → P : FE F0 FD  ; repeat many times
P → R : FE F0 FD
P → R : FE F1 FD
R → P : FE F1 FD

Commands Radio to Panel

0x60 Display

Data to display on panel. Looks like bitmask controlling particular LCD segments/LEDs. No detailed description available at this time.



IC-706 Panel OK1CDJ


Thanks to Alex OZ9AEC for PTT details and handshake description.