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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

iebus2

iebus2

iebus3
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
circuitcomponents
sch 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
110EMV 120AVX 1281DIN TV
140AVN 144G-BOOK 160AUDIO H/U
178NAVI 17CMONET 190AUDIO H/U
1ACCAMERA-C 180Rr-TV 1C0Rr-CONT
1C2TV-TUNER2 1C4PANEL 1C6G/W
1C8FM-M-LCD 1D8G/W for Trip 1ECBody
1F0RADIO TUNER 1F1XM 1F2SIRIUS
230TV-TUNER 240CD-CH2 250DVD-CH
280CAMERA 360CD-CH1 3A0MD-CH
17DTEL 440DSP-AMP 530ETC
5C8MAYDAY 1A0DVD-P 1D6CLOCK
1F4RSA 1F6RSE 480AMP
1CCST.WHEEL CTRL

 
table : logic device ID
01communication ctrl 58navigation ECU 80GPS receiver
21SW 23SW with name 25command SW
12communication 60tuner 74Audio amplifier
61tape deck 62CD 63CD changer
34front passenger monitor 24SW converting 85voice control
E5Trip info 55Bluetooth tel 56information drawing
5DClimate ctrl drawing 5EAudio drawing 5Ftrip info drawing
28beep dev in HU 29beep via speakers E0climate ctrl dev
5Ccamera

 
Example of command transmission (this it BEEP request , sent by EMV to DSP-AMP):
command
1start bit
2regular command (not a broadcast)
3master device address : EMV
4slave device address: DSP-AMP
5control field - WRITE data
6length of data: 5 bytes
70x0 when device-to-device communication; nothing when broadcast
8from logic device id
9to logic device id
Acommand
B-..command parameters
 
logged command map (all values in HEX format):
broadcast (C)going to LAN check mode
0160FFFF301C             

broadcast (C)back from LAN check mode
0160FFFF31210             

broadcast (C)LAN restart
0160FFFF31211             

broadcast (C)any device is use
0160FFFF312146             

broadcast (C)xx=60,61,62,63... logic device ID in use
0160FFFF412145xx            

broadcast (C)xx=frequency, yy=0 - radio is oFF, yy=1 - radio is ON
01601FFFD6031F1yyyy81xxxxxx810800   

broadcast (C)AF+REG enable
01601FFFD6031F111810118110800   

broadcast (C)VOLUME vv=0-FF
01601FFFF7431F190vv101010101000030 

broadcast (C)BASS bb=0B-15 : 0B=-5, 10=0, 15=+5
01601FFFF7431F190vv1010bb101000030 

broadcast (C)TREB tt=0B-15 : 0B=-5, 10=0, 15=+5
01601FFFF7431F190vv10101010tt00030 

broadcast (C)FADE ff=0B-15 : 0B=F5, 10=0, 15=R5
01601FFFF7431F190vv10ff10101000030 

broadcast (C)BALANCE bb=09-17 : 09=Left7, 10=0, 17=Right7
01601FFFF7431F190vvbb1010101000030 

broadcast (C)TAPE IN
01601FFF76131F11400         

broadcast (C)TAPE PLAY
01601FFF76131F118400         

broadcast (C)DOLBY ON
01601FFF76131F118402         

broadcast (C)SKIP
01601FFF76131F1184400         

broadcast (C)REVERSE
01601FFF76131F118900         

broadcast (C)FAST FORWARD
01601FFF76131F118800         

broadcast (C)REPEAT
01601FFF76131F1184100         

broadcast (C)RANDOM
01601FFF76131F114100         

broadcast (C)TAPE EJECT
01601FFF76131F10300         

broadcast (C)NO TAPE
01601FFF76131F10000         

broadcast (C)TAPE DECK not ready (??)
01601FFF461319F0            

broadcast (C)internal CD Player not ready (??)
01601FFFB6231F100000000     

device-to-device (P)request to play Beep tt=1-?? duration
1110440F505E2960dd           

device-to-device (P)press on screen xx,yy - position xx=0-FF, yy=0-FF
1110178F80212478xxyyxxyy        

device-to-device (P)BALANCE slide d-direction d=9C up, d=9D down, r=1-4 relative pos.
1190440F502574dr           

device-to-device (P)BALANCE bb=9-17
1190440F50257491bb           

device-to-device (P)FADE ff=9-17
1190440F50257492ff           

device-to-device (P)BASS bb=B-15
1190440F50257493bb           

device-to-device (P)MID mm=B-15
1190440F50257494mm           

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
13601FFFB6331F101ssddttmmeepp80     

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

Do you know more?


 

To be continued....

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