2. AVC-Lan - how it work ?

2.1 Transmission layer

AVCLan is based on IE-Bus (Electrical Interface Bus) defined by NEC. IEbus Description
Devices made by NEC are very difficult (or just impossible) to purchase, so we need build own receiver for talking to AVC network. The NEC public datasheet for uProcessor and receiver where are informations how to IE-Bus work.
datasheet 1 datasheet 2
WIKI infopage
Most important informations:
iebus

After this, we know, that one single bit duration is about 39 uS.
( 390us for 8 bit of data, 1 parity bit and 1 ACK bit : 390/10 = 39 )

This is a part of AVC communication between devices: beep

Now, we can identity logic "0" and logic "1" by count time of duration high state of the transmission line.
Let single bit duration on the bus is 40 uS. Logic "0" is 33uS high and 7uS low, logic "1" is 20uS high and 20uS low.
I discover that on transmission layer AVC-Lan is the same as Pioneer (blue) IP-Bus.
(More information about other CD Changer Protocols)

2.2 Hardware layer

Focus that minimal 'low' state is 2 uS (

)! Is it short time? Yes, it is, but not in digital transmission world - read something about CAN network.
iebus5

circuit	components
	U - Atmega8 U - LN239N U - PCA82C250 U - DS1813R (optional) R - 2 x 180, 120, 1M, 3k, 2 x 10k C - 2 x 22pF, 100nF X - 14,7456 MHz

My experimental device and transmission part:

2.3 Protocol layer

Every device in network have unique address.
When single device have more functions, then additional 'logic id' exists.

table : hardware address and device names

110	EMV	120	AVX	128	1DIN TV
140	AVN	144	G-BOOK	160	AUDIO H/U
178	NAVI	17C	MONET	190	AUDIO H/U
1AC	CAMERA-C	180	Rr-TV	1C0	Rr-CONT
1C2	TV-TUNER2	1C4	PANEL	1C6	G/W
1C8	FM-M-LCD	1D8	G/W for Trip	1EC	Body
1F0	RADIO TUNER	1F1	XM	1F2	SIRIUS
230	TV-TUNER	240	CD-CH2	250	DVD-CH
280	CAMERA	360	CD-CH1	3A0	MD-CH
17D	TEL	440	DSP-AMP	530	ETC
5C8	MAYDAY	1A0	DVD-P	1D6	CLOCK
1F4	RSA	1F6	RSE	480	AMP
1CC	ST.WHEEL CTRL

table : logic device ID

01	communication ctrl	58	navigation ECU	80	GPS receiver
21	SW	23	SW with name	25	command SW
12	communication	60	tuner	74	Audio amplifier
61	tape deck	62	CD	63	CD changer
34	front passenger monitor	24	SW converting	85	voice control
E5	Trip info	55	Bluetooth tel	56	information drawing
5D	Climate ctrl drawing	5E	Audio drawing	5F	trip info drawing
28	beep dev in HU	29	beep via speakers	E0	climate ctrl dev
5C	camera

Example of command transmission (this it BEEP request , sent by EMV to DSP-AMP):
command

1	start bit
2	regular command (not a broadcast)
3	master device address : EMV
4	slave device address: DSP-AMP
5	control field - WRITE data
6	length of data: 5 bytes
7	0x0 when device-to-device communication; nothing when broadcast
8	from logic device id
9	to logic device id
A	command
B-..	command parameters

logged command map (all values in HEX format):

broadcast (C)					going to LAN check mode
0	160	FFF	F	3	0	1	C

broadcast (C)					back from LAN check mode
0	160	FFF	F	3	12	1	0

broadcast (C)					LAN restart
0	160	FFF	F	3	12	1	1

broadcast (C)					any device is use
0	160	FFF	F	3	12	1	46

broadcast (C)					xx=60,61,62,63... logic device ID in use
0	160	FFF	F	4	12	1	45	xx

broadcast (C)					xx=frequency, yy=0 - radio is oFF, yy=1 - radio is ON
0	160	1FF	F	D	60	31	F1	yy	yy	81	xx	xx	xx	81	0	80	0

broadcast (C)					AF+REG enable
0	160	1FF	F	D	60	31	F1	1	1	81	0	1	1	81	10	80	0

broadcast (C)					VOLUME vv=0-FF
0	160	1FF	F	F	74	31	F1	90	vv	10	10	10	10	10	0	0	0	3	0

broadcast (C)					BASS bb=0B-15 : 0B=-5, 10=0, 15=+5
0	160	1FF	F	F	74	31	F1	90	vv	10	10	bb	10	10	0	0	0	3	0

broadcast (C)					TREB tt=0B-15 : 0B=-5, 10=0, 15=+5
0	160	1FF	F	F	74	31	F1	90	vv	10	10	10	10	tt	0	0	0	3	0

broadcast (C)					FADE ff=0B-15 : 0B=F5, 10=0, 15=R5
0	160	1FF	F	F	74	31	F1	90	vv	10	ff	10	10	10	0	0	0	3	0

broadcast (C)					BALANCE bb=09-17 : 09=Left7, 10=0, 17=Right7
0	160	1FF	F	F	74	31	F1	90	vv	bb	10	10	10	10	0	0	0	3	0

broadcast (C)					TAPE IN
0	160	1FF	F	7	61	31	F1	1	4	0	0

broadcast (C)					TAPE PLAY
0	160	1FF	F	7	61	31	F1	1	84	0	0

broadcast (C)					DOLBY ON
0	160	1FF	F	7	61	31	F1	1	84	0	2

broadcast (C)					SKIP
0	160	1FF	F	7	61	31	F1	1	84	40	0

broadcast (C)					REVERSE
0	160	1FF	F	7	61	31	F1	1	89	0	0

broadcast (C)					FAST FORWARD
0	160	1FF	F	7	61	31	F1	1	88	0	0

broadcast (C)					REPEAT
0	160	1FF	F	7	61	31	F1	1	84	10	0

broadcast (C)					RANDOM
0	160	1FF	F	7	61	31	F1	1	4	10	0

broadcast (C)					TAPE EJECT
0	160	1FF	F	7	61	31	F1	0	3	0	0

broadcast (C)					NO TAPE
0	160	1FF	F	7	61	31	F1	0	0	0	0

broadcast (C)					TAPE DECK not ready (??)
0	160	1FF	F	4	61	31	9F	0

broadcast (C)					internal CD Player not ready (??)
0	160	1FF	F	B	62	31	F1	0	0	0	0	0	0	0	0

device-to-device (P)					request to play Beep tt=1-?? duration
1	110	440	F	5	0	5E	29	60	dd

device-to-device (P)					press on screen xx,yy - position xx=0-FF, yy=0-FF
1	110	178	F	8	0	21	24	78	xx	yy	xx	yy

device-to-device (P)					BALANCE slide d-direction d=9C up, d=9D down, r=1-4 relative pos.
1	190	440	F	5	0	25	74	d	r

device-to-device (P)					BALANCE bb=9-17
1	190	440	F	5	0	25	74	91	bb

device-to-device (P)					FADE ff=9-17
1	190	440	F	5	0	25	74	92	ff

device-to-device (P)					BASS bb=B-15
1	190	440	F	5	0	25	74	93	bb

device-to-device (P)					MID mm=B-15
1	190	440	F	5	0	25	74	94	mm

broadcast (C)					CD status: ss=10-play, ss=80-load, ss=01-open, ss=02=err1, ss=03-wait dd-disc no, tt-track no, mm-play time min., ee-play time sec pp=0-normal, pp=2-disc rand, pp=4-rand,pp=8-disc rep.,pp=10-rep.,pp=20-disc scan, pp=40-scan
1	360	1FF	F	B	63	31	F1	01	ss	dd	tt	mm	ee	pp	80

(C)-logged in Corolla, (P)-logged in Prius

Do you know more?

To be continued....

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