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Android based infotainment system for Linea T-Jet on a shoestring budget.

Discussion in 'Do It Yourself' started by PatchyBoy, Oct 4, 2012.

  1. He fixed it on the Sun guard(not sure if this is the term) on the driver side...
  2. funkykar

    funkykar BANNED

    Fixed it using? Any pictures would be appreciated :)
  3. Didnt get a chance to get a snap,he used some elastic band to fix it on it..It looked pretty neat..
  4. PatchyBoy

    PatchyBoy Esperto

    @funkycar: Here are some pictures as requested

    The GPS unit comes with a magnet, which is fixed using double side tape to the car

    Once the GPS receiver is docked, it looks like this

    And this is how the tablet looks mounted on the Sun Visor. The bands used to hold the tablet in place is the typical lanyard, on usually finds around people's neck with an ID attached :D. It is slightly stretchable, quite strong and held up the tablet quite nicely for the entire 500 + km trip. I am working on a more robust design which will clip on to the sun visor.

    A closer look. The Bluetooth dongle is tucked into the document holder flap

    Torque Pro tells me that the GPS accuracy is 2.7 meters, which I hope is reasonably good. However GPS speed says 0.3 km/h, though the car was parked :D


    Last edited: Oct 10, 2012
    2 people like this.
  5. funkykar

    funkykar BANNED

    Many thanks!!! Appreciate you taking time and posting pics. I will hold on to the suction mount until it can and then probably try like your setup. Only advantage with suction mount is the unit can be used as a video player too and when played all can see
  6. mvb4u

    mvb4u Regolare

    Grande Punto 1.3
    Nice DIY. Actually, I am considering adding a dedicated PND from mapmyindia and hesitating that it is not useful for any other purpose than the purpose for which it was designed. Then happened see this thread.

    Now, I am planning to get the same setup with same Jentro GPS receiver you, have used but the tab I am considering is either aurora II or Crystal from ainol novo 7 series. The only difference between your tab and what I am considering is the IPS screen. Better clarity. And the same can be used a video player for others in the car.

    Nice DIY. And Thanks for sharing Patchboy.

    Will also get BLUETOOTH OBD ELM 327 scanner.
  7. PatchyBoy

    PatchyBoy Esperto

    MODS: Please change the thread title to - Android based infotainment system for Linea T-Jet on a shoestring budget.

    OK. I now have Aux-in on the HU :D


    The circuit printed on the HU does show Aux-In pins, but they are used by B&M. If we refer the attached wiring diagram (Sorry, could not find an English version), we can see that the wiring logic is like this:

    1. B&M reads the audio file from the USB
    2. The Audio codec/processor in the B&M unit streams this to the Aux-In on the HU
    3. HU plays the music

    Therefore, we can safely assume that, should we connect wires to the 3 pins - Aux L, Aux R and Aux Gnd - with a 3.5 mm jack on the other end, we must be able to play music from any device with a 3.5 mm stereo out. However, this would mean that we will lose the ability to play music from the USB on B&M (Might lose additional functionality too, not sure). However, if we splice the Aux wires on the ISO connector and attach the 3.5 mm stereo pin, we must be able to use both functionality, or would we?

    I believe, there would be logic built into the B&M unit to recognize the device attached to the USB port and will be able to mute that, when a call comes in. This being the case, I doubt if the parallel Aux cable would work without a device plugged into the USB drive. But that would mean playing 2 tracks simultaneously. Audacity to the rescue. This software would allow us to create a MP3 track, with just silence. Yes, there is an option to generate SILENCE, which creates a MP3 track of whatever duration we specify with just silence.

    Theoretically, if we put this on a pen drive, use the B&M's media player to play this, while simultaneously playing Audio output from the device connected to the 3.5 mm stereo jack, we should be able to achieve what we set out to do. However, the catch is, if a call comes, B&M will not mute the device's sound input. It will only mute silence

    How I did it:
    1. Prepare a speaker wire of desired length and fit a 3.5 mm stereo pin in one end. Cut and expose the wires at the other end
    2. Remove the HU and disconnect everything
    3. Locate the 3 wires marked AUX R, AUX L and AUX Gnd (Could be AUX followed by an inverted T)
    4. Now push a thin strong object (I used a sewing needle) alongside the + slot from the front of the connector, while gently pulling the wire
    5. When you have pushed the locking tab in and pulled the wire simultaneously, the whole thing will slide out. Takes a bit of effort and a lot of patience.
    6. Connect your wires. Red to AUX R, White to AUX L and the open strands inside the outer sheath to ground.
    7. Push the pins back into the ISO connector. Make sure you put them back in the correct slots
    8. Leave a little slack and tie to the rest of the cable to prevent tugging
    9. Route the cable to the desired location. In my case, it is routed up the A pillar, to the roof liner and comes out near the driver side sun visor
    10. Put the HU back in place

    We are done. As expected, the following issues exist

    • You have to create a silent MP3 track, copy it to a USB stick and play that, while playing your music from the tablet
    • If a call comes in, you can take it on the B&M, but the audio from the tab will not get muted. Only the silent track will get muted
    • If you press the mute button on the steering wheel, the silent track will get paused, but the audio input from the tablet will continue playing. You cannot hear it though, as it will not be routed to the speakers.

    So, why go into all this trouble? Easier to just play the music from an USB stick, right? The advantages as I see it:

    • Voice guided navigation from the tablet goes to the car speakers
    • Playing a video clip on the tablet will route audio to the car speakers
    • With a mobile wifi hotspot, stream media is possible
    • If it is not broken, don't fix it. Just add more features :D


    View attachment Radio, Subwoofer y convergence2.pdf

    4 people like this.
  8. theblack

    theblack Esperto

    amazing job man.. the torque pro on a big tab looks really really great.
    Nice teky job you did there..
    What did you use to get the torque pro working? what is the modle of the BT receiver you attached to the OBD port?
  9. mvb4u

    mvb4u Regolare

    Grande Punto 1.3
    From the label on the delphi head unit AF L, AF R, AF GND (INVERTED T IN THE MIDDLE) I believe, to be front aux Left, front aux Right, front aux Ground pins. Don't know whether they are enabled or disabled in the internal circuit of the head unit. But, I strongly feel that they are not disabled. Why not give a try by connecting the aux wires to these pins rather than to B&M pins in parallel?


    Pin No.18 is AF GROUND
    Pin No.19 is AF LEFT
    Pin No.20 is AF RIGHT

    Pin No.6 is switch the output of which is useful to turn on/off amp with head unit by connecting the remote turn on lead of amp to this one rather than to a switch or to another fuse or wire controlled by ignition switch.

    DIY on this has been posted on diy section.

    Last edited: Oct 14, 2012
  10. PatchyBoy

    PatchyBoy Esperto

    Thanks for the tip. I doubt if pins 18,19 and 20 will work as they are meant for CD changer and would possibly also expect CDC Data in and CDC data out. Did not try it though, so not sure.

    A question for all DIYers, how do I get a 5V DC supply to keep the tablet charged? Would prefer a lot heat solution.

    Would this be a good idea?


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