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JVC stalk adapter - DIY?

Discussion in 'ICE, Sat Navs & Dash Cams Forum' started by pleriche, Sep 29, 2005.

  1. pleriche

    pleriche
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    I recently bought one of the last of the Rover 25s available new, which came with a dealer-fitter JVC KD-G152 - no stalk control and no CD/MP3.

    I've almost decided to upgrade to a JVC KD-G612. Stalk adapter would add £30, assuming I can find the right one. But it strikes me, it should be easy to DIY it.

    I suspect the stalk control input on the JVC is simply a 3.5mm stereo jack socket (easy to obtain a plug, if I haven't already got one).

    First question: am I right?

    The loom has a rectangular multicolour block connector hanging loose, with 20 pin positions but only 2 used. These must be the stalk controls, each of which probably switches between +12v and ground for "up" and "down". (Will check with a test meter when I get the chance.) Since I learnt to solder some 45 years ago, taking the 2 wires which go into the multicolor connector into a stereo jack plug seems less than challenging.

    Second question: is there a flaw in my logic somewhere?

    Thanks - Philip :cool:
     
  2. pleriche

    pleriche
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    The Haynes manual confirms that the two wires (pink and white) going into the multicolour block are the stalk controls. So I connected a test meter (20v range) between each of these and earth, and between each and +12v, each time waggling each of the stalk controls controls both ways. Not so much as a flicker from the test meter. So if the stalk controls don't switch the wires to either ground or +12v, what do they do? Haynes' circuit diagram simply shows 2 single pole switches to ground. :confused:

    Meanwhile, a helpful shop assistant this morning allowed me to confirm that the stalk control input on the KD-G612 accepts a standard 3.5mm stereo jack.
     
  3. pleriche

    pleriche
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    Aha! Light begins to dawn.

    The stalk controls connect various values of resistance between the pink and white wire, as follows:
    Vol down: 0
    Vol up: 400
    Skip up: 800
    Skip down: 1600 ohms
    A post on another forum indicates that for a Ford Focus, the values are 50, 150, 300, 550 ohms.

    Does anyone know (or can anyone please measure) what values the JVC expects? I'm within sight of my DIY stalk adapter, and will gladly share the results when I get there.
     
  4. pleriche

    pleriche
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    One or two people seem to be reading this thread so I may as well report progress so far.

    I bought the JVC KD-G612. Connecting various resistors across the stalk control input has no effect whatsoever. Putting a meter across it indicates that the live connection goes to +5v through approx 22k (if I remember correctly), strongly indicating that it's a serial data connection. May be possible to drive it from a laptop COM port via an RS232 - TTL converter (e.g. MAX232) but would take a good bit of fiddling with baud rates etc to suss it out. Gotta be worth a try before forking out £40 for a Connects2 solution.

    In general my guess is that there is little standardisation in this field, which is bad news for anyone like myself trying to home-brew.
     
  5. Curry Monster

    Curry Monster
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    go to HALFRAUDS and buy an adaptor for about £20
    job done
     
  6. pleriche

    pleriche
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    Where's your natural curiosity, and your sense of fun and adventure?? ;)

    Anyway, how many return trips do you estimate before they supply the right one?
     
  7. Curry Monster

    Curry Monster
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    ...mmm me thinks you have been to halford before!!!!!

    www.autoleads.co.uk

    or ring them cos they supply halfrauds!!!
     
  8. pleriche

    pleriche
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    OK, cracked it. For the benefit of anyone picking up this thread from Google at some date in the future, here's the result.

    I bought a stalk adaptor from InCarTec for a huge sum of money. I connected the output to the mic input of my laptop via a suitable attenuator network. (DON'T try this yourself unless you know what you're doing - you risk damaging your laptop.) Then I recorded the signal with Audacity. (Any other audio editing program would do.) Attached is the result as mp3, showing the results of:
    Vol+ (04)
    Vol+ hold (04 repeated)
    Vol- (05)
    Vol- hold (05 repeated)
    Skip fwd (12)
    Skip fwd hold (14)
    Skip back (13)
    Skip back hold (15)
    (decoded control codes in brackets).

    The quiescent level is 5v, with 0v pulses. The coding seems to be similar to an IR controller, in fact if you used the output to modulate a 38 or 40kz IR signal, you'd probably get valid IR control codes - see http://www.epanorama.net/links/irremote.html

    Essentially, 5v for 550uS represents "0" and 5v for 1550uS represent "1". There seem to be 2 start bits and one stop bit. Between them is an address (7 bits, always 47hex) and a control code (7 bits). Both are transmitted least significant bit first. The control codes are as above. The whole packet is repeated 3 times (possibly the receiver is designed to vote for the most popular if one arrives broken) and they are preceeded by an 8.5mS agc pulse.

    Any reasonably bright 16-18 year old could generate these codes with a PIC microcontroller. Unfortunately I no longer need to (and anyway, I left my adolescence behind more years ago than I like to remember.)
     

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  9. shirubaby

    shirubaby
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    Well done...this is just what I need for my remote stalk project. I'm planning to contrsuct a jvc remote wired stalk-type interface with micro switchs placed in my steering wheel. My Merc doesn't come with any controls.

    HOWEVER, I am trying to understand the JVC protocol and the mp3 file. I cant see the 47hex....
    From the mp3 file:
    if you take the very first bit pattern after the agc pulse...it goes (reading from left to right in Audacity) 11 1100010 0100001 and then the stop bit....now if the 1st 2 bits are the start bits and the address bits are next (lsb first) we get an address of 0100011 which is 23hex.
    We get a command of 1000010 which is 42 hex.

    What am I missing here....
     
  10. pleriche

    pleriche
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    Heck, this is a few months ago. Glad you found it useful.

    Just taken another look at the mp3. I should have said that the waveform is inverted. Also, I probably misinterpreted the gap following the agc pulse as another "1" - there is only 1 start bit.

    The address and data are each only 7 bits, "little-endian", so 47Hex comes out as 1110 001.

    See the attached ascii-art waveform.

    Good luck - you'll certainly have fun!

    Regards - Philip
     

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  11. shirubaby

    shirubaby
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    It's still not finished but a result was achieved today.

    After a long time contemplating about getting round to this I finally developed (using the info above, thanks pleriche) the code to control a jvc car stereo.

    The stereo I have installed in my car is a jvc kd-g421. I guess it will work with most jvc car stereos. I suggest people read the full thread before attempting to install this circuit in ones car.

    The jvc stereo is coupled with an ipod integration kit (£39.99 special offer from Halfords) which means I can remotely control my ipod as well...cool. This kit (ks-pd100) charges the ipod and transfers music through the dock port on the ipod. It also allows control of ipod through the stereo buttons. So the top of the range integration kit.

    The assembler code (attached) should contain everything you need to understand the pulse patterns, timings and button interfaces.

    the system assumes the jvc has a remote control interface at the back which is a 3.5mm stereo jack socket.

    (refer to assembler code header for diagramme1)

    SIG is connected to the pic output pin. GND is earth and is the same as the stereo earth.

    A 5v regulator is used betweent the pic and the power supply.

    the pic input pins are tied to 5v+ so that they are held high when buttons are not in use (internal weak pull-ups
    on the pic micro can also be used for this purpose where available).

    (refer to assembler code header for diagramme2)

    That's all! Simple huh?
     

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  12. micutu

    micutu
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    hy, i was wondering if you can help me with this constructions, I have knowlege with electronics but not so much with PIC's. Please help me.
    Can you provide a schematics for the project?
     
  13. micutu

    micutu
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  14. shirubaby

    shirubaby
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    hi there,
    Sorry for the delay. I didn;t thikn anybody would be interested in following what i did....I will get the diagrammes to you soon
     
  15. shirubaby

    shirubaby
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    have a look at the pdf
     

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  16. shirubaby

    shirubaby
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    assembler code here:



    hope this helps...any questions...send me a pm
     

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  17. micutu

    micutu
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    yes, thank you verry much for your answer, however, i need to make a priject like the original stalk interface there are not availeble in my country, I have an original ford steering remonte, and a jvc, can you provide the sources for that, I need to study and maybe i can make what i need.
     
  18. shirubaby

    shirubaby
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    I understand. I created everything from scratch. The buttons I used are small micro switched. You can use the buttons from any interface (like ford).

    But bewarned...some remote stalk interfaces multiplex some buttons onto a reduced set of wires (e.g. 3). I cannot help you with this because I dont have the particular interface.

    I hope you understand what i am trying to say.
     
  19. shirubaby

    shirubaby
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    maybe these pics will help
     

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  20. valvola

    valvola
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    Hello,
    First of all, thank you very much for yout job.
    I am trying to do about the the same here.
    The main difference are that:
    1) I need to I need to take the steering wheel control input from CANBUS instead of direct wires...
    2) ...so I am using PIC18 series MCU with built in CAN support
    3) and C (from mikroelektronika) instead of assembler
    4) I have a KD-DV6202 car stereo, but I assume the interface works just the same. It has also an IR remote (RM-RK230) working at 38khz

    I started the project before reading your thread. First of all I didn't have an original stalk control and so I made an IR receiver (vishay tsop 1738 based) to figure out something about the JVC IR codes.
    The codes I am getting are waaaaay longer than 14 bits, anyway only a few of the last bits change between each remote button. Probably the first part of the stream is optional.

    I am currently able to "repeat" recorded IR codes using an infrared led, it works perfectly. Now I will try to interact with the wired remote connection.

    Bye and thanks again
     
    Last edited: Jul 14, 2008
  21. AlxMAX

    AlxMAX
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    Hi,

    It's hell of a job indeed and I appreciate it very much!

    I would like to ask a question. I have read the thread and I have seen the signal applied on the steering wheel command jack with the help of your device resembles with the signal emited by an infrared remote controller. I have the same player as shirubaby, JVC KD-G421 and I wonder what happens if we apply on the steering wheel command jack of the player the signal of the remote controller JVC RM-RK60 that is normally used to drive the IR LED.

    Alx.
     
  22. shirubaby

    shirubaby
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    they should have the same codes...and work exactly the same...please post findings...:thumbsup:
     
  23. dusiciel

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    Hi!
    Finally I found this board, it took me all day to find any info about jvc remote protocols. Thx guys for all that info.

    Unfortunatly Im not familiar with coding/programing microcontrolers, wonder if any of the premade controlers will work with that (IR remotes one).

    My goal is to connect a JVC radio (kd-g332 in this case) to the opel/vauxhall steering wheel controls.

    I have found out how the those works (attached picture).

    To be honest i have no idea how to make/write assembler file to program a microcontroler, to read the resistance values from a steering wheel.
    I think many people could find this useful if they know how to do it.

    Any help will be much appreciated.
    Thank you.
     

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    Last edited: Jul 21, 2008
  24. freddyokel

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    So, what DID you find out about JVC remote protocols?

    I'm very familiar with coding microcontrollers and would like to interface the 4 wired resistance type controls on my Rover 200 to control my JVC KD-G331.

    If I knew anything about the protocol then this would be a trivial single chip job, which could probably be done with a PIC, a voltage reg. and no other external components.

    Fredd
     
  25. kurtoslaw

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    Hello, i'm building interface renault joystick -> JVC KD-G511:)

    What is AGC signal? (what for it is and length of high/low (time of it) i need;) ).

    BR Kurt
     
  26. drobb

    drobb
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    pleriche, thanks for posting that info for future people searching the web. 6 years later, this thread appears to be the only place on the internet where this info is available. I have some more info for whoever else ends up here.

    I've got a JVC KD-AHD79 head unit. It has a blue with yellow stripe wire for the wired remote instead of the 3.5mm jack that JVC used to use. The wire is pulled up to 3.3V (measured as 3.278V) through a resistor that seems to be exactly 22.0k ohms. I was assuming they were using a tight-tolerance resistor to work as part of a voltage divider for resisitive input, but the unit gave no response to a wide variety of resistors. Then I found this thread.

    I haven't attempted interacting with the head unit yet, but i do have some new codes and some exact timing info that I learned from the infrared remote that came with the headunit (The JVC RM-RK52).

    I suspect the nominal modulation frequency is 38212 Hz. Normally we wouldn't care for a wired application where there is no modulation frequency, but measured in terms of modulation periods, the timing structure of the data seems simpler.

    A modulation period is 1/38212Hz or roughly 26.1968 uS. A 'mark' is 20.5 modulation periods of high output. A 'space' is 20.5 modulation periods of low output. A zero bit is represented by one mark and one space. A one bit is represented by one mark and three spaces. I'll use the symbols ~ and _ for mark and space.

    ~ is a mark, 20.5 periods (about 536.5 uS)
    _ is a space, 20.5 periods (about 536.5 uS)
    ~_ is a zero, 41 periods (about 1.073 mS)
    ~___ is a one, 82 periods (about 2.146 mS)

    The timing on the AGC period is 323 periods high followed by 161 periods low, but the timing on that probably isn't critical. It's just there to give the receiver a bit of time to figure out how strong the infrared signal coming in is. With the wired remote, you might even be able to leave it out completely.

    And as already explained, after the AGC comes one start bit '1', seven bits for the address, always 0x47, seven bits of code, the first '1' stop bit, and the final stop bit which could be a '1' or a '0'.

    And here are the button codes on my remote:
    0x04 Vol +
    0x05 Vol -
    0x08 Source
    0x0D Sound
    0x0E Mute
    0x12 Right
    0x13 Left
    0x14 Up
    0x15 Down

    Unlike pleriche's InCarTek stalk adapter, when you hold down left or right on my remote, it just repeats the same code as you get when just pressing. The 0x14 and 0x15 pleriche got from holding the skip buttons, are assigned to up and down on my remote.

    Also notable: When holding buttons on my remote, the repetition pattern is much more regular and steady than what pleriche's mp3 shows. The InCarTek adapter apparantly will do an AGC pulse, repeat the code three times, wait for a rather long period, and then repeat starting with the AGC pulse. With the JVC infrared remote, there's only a single AGC pulse and then only the code repeating.

    The .rar file I'm attaching is actually in zip format and contains oscilloscope screenshots. If you have trouble opening the file, rename it to .zip. But all of the images in the file are currently available here, and hopefully they'll last well into the future: JVC Infrared Car Audio Remote RM-RK52 - Imgur

    Realize those readings were taken directly off of the pins going to the infrared LED. So the absolute voltages aren't meaningful. And the modulation frequency doesn't belong there at all on the wired remote interface.

    Also, regarding my 38212 Hz number: I do wonder about that being a strange looking number. But I do have a very good measurement of 9 '1's and 7 '0's taking 26.82165ms. That works out to extremely close an even 466 Hz for repeating ones -- off by only 0.009% . Dividing a 'one' into 4 equally spaced parts (a mark and three spaces), and counting 20.5 periods per mark gives 38.212kHz. Even if the 38.212kHz rate is not the ideal modulation frequency, the math works out that you're hitting the actual data symbol rate exactly, assuming that 466 Hz for repeating ones is the actual nominal timing.

    Anyway, the start bits are there to synchronize the data words, so you can be off by a few percent and it'll still work.
     

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  27. drobb

    drobb
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    A minor update: I've found that the blue/yellow wire on my head unit does indeed expect these remote control codes. I don't have a nice PIC setup that reads my steering wheel controls yet, but I've got the head unit's wired remote input working in the lab by connecting it to the infrared remote's LED pins. A small circuit removes the modulation frequency, inverts the signal, and only pulls the HU's remote wire down, never driving a voltage onto it, so it should work with 5V remote lines too.

    Attached is also a screenshot of what the signal on the wired remote line actually looks like when driven by this circuit.
     

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  28. fratello

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    I'm looking for long time the codes for JVC remotes ...and I found them on this forum ! Great !
    But... I intend to build one interface, with microcontroler, between remote control stalk near the steering wheel, from Renault, and JVC auto-radio.
    I have some (little) experience in PicBasicPro (only !) and I need, for my code, to "translate" the information from this topic. So, can someone, PLESE, to explain me how can I use the information ? What is the "full" code from each command and what are the timming of each "0", "1", "0 long", "1 long" ?
    Example : Volume Up = AGC, after the AGC comes one start bit '1', seven bits for the address, always 0x47, seven bits of code (0x04), the first '1' stop bit, and the final stop bit which could be a '1' or a '0'.
    How are AGC code ? How "seven bits for the adress" ?

    I want something like this : Need Alpine wired remote control pinout.

    Thanks in advance !!! Best regards !
     
  29. fratello

    fratello
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    This timming I dont understand...
     

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  30. fratello

    fratello
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    Nobody can help me ?
    I made some captures of signals, but still not have timmings ...
     

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