Sp33dy1969
October 23, 2007, 8:57 pm
shcm,
Firstly what do you do? I'm an RF electronics senior engineer based in Birmingham... (I see your in the mid's too) and yes not so good on the mechanics too
Secondly, I agree that you would indeed need an interface to the AVC bus and then switch the line level audios as required etc.
As for fooling the head unit, yes this could work... but the question is how do the ID's work. Does each AV device have a fixed ID given to them during production? Or do they get assigned an ID by the Head unit? Then comes the matter of software / control codes etc? And what the Head unit in question can control.
I guess the best way to play this would be either build the aux in interface as described on the corolla page and try it. or build a AVC-LAN sniffer to find the ID's & codes that would work with each Head unit as required.
The problem is, like you I too have a day job

and secondly I can't really afford to have the head unit out of my car for the length of development time that would be required for this sort of project.
Then you have to ask, would it be worth it? i.e. if I did all this work on my full screen unit and it worked, there would be no guaranties of it working on other head unit types.
BTW I know of many devices that are capable of talking to the head units via the AVC-LAN: -
Single CD.
CD Changer.
MD Changer.
DVD.
DVD Changer.
DAB Tuner.
TV Tuner (Lexus only i think)
US Sat Radio Tuner.
Multi Screens + DVD
Remote Audio & Rear Head phones.
IPOD interface.
And so on...... and so on.
FYI... here's the hardware & ID tables from the Corolla MP3 site: -
Every device in network has 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
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
Sorry about the long post and going slightly off topic...
Best regards
Sp33dy.