Adding Bluetooth Audio Playback To A Toyota Matrix

In this project [Ryan] shows how he added Bluetooth audio to the stock stereo of his Toyota Matrix. The work he did with his add-on hardware is quite good. And the installation was surprisingly easy. For example, the dashboard bezel which is hanging in the foreground of this picture simply pulls off without the need for any tools. Also, the CD changer input for the stereo is what he uses to patch into the system. It just happened to have a 0.1″ pin header so finding a connector that would work wasn’t a problem.

As for the add-on hardware, he built his own circuit board around an ATmega168 microcontroller and Bluegiga WT32 Bluetooth module. To connect to the car’s data system he went with an RS485 driver chip. It’s not quite the right part but it works well enough for his purposes. So far he can get audio playback working and plans to add support for hands free phone calls and displaying audio track information. Hey, maybe he’ll even add some extra shake-based automation; who knows?

Get a look at the install in the clip after the break.

16 thoughts on “Adding Bluetooth Audio Playback To A Toyota Matrix

  1. Nice setup! Really like what he did! Will be interesting to see what he adds to it!

    Did a plugin to the AUX CD port with a bought adapter on my previous (05)matrix for Aux In. Interesting to see he had the same problem with low audio I had.

    On the new matrix (04) just replaced the old GM junk radio it came with with a JVC WKAV70BT. It loves my feature phone and with cable lets the iPad interface to it for audio and display. Was not hard to pop it in.

  2. The problem with this sort of hack is that in spite of the cleverness of what he has done, since you can buy FM transmitters with streaming bluetooth input, as well as pause/play, skip forward, and skip back buttons for not much money, was it worth it? I just get in my car, wait for the phone (in my pocket) and FM doobrie to connect, and off I go. Add in GSM, phone, and text -to-screaming harridan for email and SMS and it’s an easy and pretty complete solution. Just as well since the Android interface seems designed to cause car crashes.

    That said, all power to [Ryan] – Loved the video, it was just like being there :)

    1. FM is nice stop gap but FM has some major limits:

      1) In a crowded area near a city hard to find a channel that’s free.

      2) FM is freq limited below 15khz due to how the pilot tone to indicate Stereo. Wont get into the bottom range. Dynamic range for a regular FM station broadcaster is maybe 63 ~ 76db. MP3 is about 90db I think. CD are above 90db.

      3) Some units only do 4 freq near the lower freq of the FM band. 87.7–91.9 MHZ.

      Tried the FM path and was really feed up with the limitation and quality. Forgot who made the adapter that I plugged into the 6CD Toyota radio like he has. It had two stereo inputs and very good audio. You easily tell the difference.

      I like the creator’s build on this!

      1. I guess it depends on the FM unit you get. Mine automatically finds free channels.

        I have a Citroen C5 which is a reasonably quiet car and I really haven’t noticed any difference from either the CD player or the autochanger (2 CD players in one car? Very French :)

        Mine tunes from 88.1 to 108.9 in 0.1 increments, so there’s no limitation on where you tune it. I have noticed that both the phone and the FM thing need the volume turned down a little bit to prevent clipping, which ruins the sound on a couple of old FM things that I have. Could that be the problem you’ve noticed? The major limitation on quality ought to be streaming the music via bluetooth, with it’s comparatively low bandwidth.

        Messing with the Citroen harness seems fraught with problems. The usual trick seems to be to hack into the autochanger outputs, but some people have reported problems doing that. My car has a thing called TrafficMaster which is a useless warning system for traffic jams, and which gives audio messages through the car’s sound system that I wondered about, but the FM thingy is easily good enough, and the mess of wire behind the dashboard is seriously intimidating – Nearly all the wire is black, FFS!

      2. I once considered FM to have those limitations. I found that all of my quality problems went away when I built my own transmitter though.

        Basically, I have bought 3 different FM transmitters total. Each of them cost no less than $50 and each of them lasted no longer than 6 months. After the last one crapped out and stopped working(tiny SMD solder joints broke due to no strain relief) I was without good music for about 3 months.

        After those 3 months I decided to build my own FM transmitter around the NS73M. When I finally got it completed and ready for “production”, I had no problems. Quality is excellent(although I need a few filter caps). Even with a 3 inch antennae it will override fringe stations within a 20-40 foot radius. Also, it works and I don’t see it breaking anytime in the next few years. Powered by USB and all parts included, it ended up costing me only $40.

        That being said, it’s not “legal”, but I use such a small antennae I doubt anyone will ever care. I really wish the legal Part15 power for FM transmitters would be increases by 25mW or so. The pollution and lack of spacing in populated areas is pathetic

    2. The nifty part of what he did here was the integration with the car stereo itself. Using a microcontroller to patch into the changer controls, so he can operate the phone from the stereo’s built in buttons is just cool.

      I too have been working on a WT32 based bluetooth device( off and on for MONTHS now… doubt it will ever be truly finished). I also have been having issues with the audio output levels involved. I’m already using a TS482 opamp package in an effort to amplify / convert the differential outputs from the WT32 before piping it into the line-in jack on my carpc. Even with that the volume is very low.

      I had hoped to learn something from Ryan’s build, but he too is struggling with the low output volume from an otherwise awesome bluetooth module.

  3. Hi Bacchus

    FM is ok if that’s the only thing. There is a level problem on getting the right audio level into a FM unit. If FM work for a person. Good! Glad you got something that works well for you!

    When I pop the new head unit in went with an adapter kit. Hate splicing. There are two or three companies offering plugs to work like the stock header unit.

    Took about a week to get the new head unit and the two kits to install it without splicing and fitting it in. I don’t blame you. ^_^ Had major questions on the amplified antenna and two wires that had to research pretty hard on the Matrix.

    Need to add BkUp camera which will hack to add two front Lf/Rt cameras and maybe two back ones besides the tail one. Hate blind exits.

    The unit in the previous Matrix had problem on volume. Could be like he found out. Its designed to take a higher signal to make it work.

    1. Nightstar:

      The snag with an adaptor plug replacing the autochanger on a C5 is that “people have reported” that on some models the computer starts misbehaving when it notices the autochanger is missing, with the same thing happening if you splice in to the audio with a jack (wired to swap sources). I’m not too sure I believe this, as I can’t see how the computer could tell where the audio is actually coming from – The autochanger is still online. People who claim to know reckon that you have to disable the autochanger on the computer, and you have to find someone prepared to do that for you as it isn’t a Citroen-approved setting .

      I would like a more integrated solution, particularly one that doesn’t involve as much mobile phonery as my wife also drives the car and hates Android, so she doesn’t carry the ~25GB of music on her phone that I do.

      I reckon that FM doobries are like anything else – You get what you pay for. The spec on mine is:
      * Bluetooth v2.1 +EDR
      * Profiles: Headset, handsfree, A2DP, &AVRCP
      * FM freq: 88.1MHz -> 107.9MHz in 100KHz steps
      * FM modulation: 20Hz to 20KHz
      … plus USB charging and audio line in and line out sockets. It cost me UKP30(ish), a big step up from the cheapest I saw – UKP1.99, but that had a more modest spec :)

      Don’t get me wrong – I’d do it your way if I thought there was a reasonable chance of success, but since stuff like the lights and windscreen wipers, and even the rear view mirror dimming function are all automatic, the car would probably be undriveable if the computer craps out :(.

      1. I agree its too big of a risk to do it! FM is the only smart thing to use. That computer is kind of like the one in the Matrix. They run the planet through it.

        The one thing that burns me up on car units that can do USB to iDevice. Is they ignore the iPad!

  4. Until we get to bitsteram to class D amplifiers, we must keep to as FEW as can be the number of layers of conversion and mostly compression (truncation).
    Bluetooth stereo (not). Stereo meens solid (image) not just 2 channels of poor bitrate crap. Till then wire it up. Most FM mods suck, I have modded one Ramsey Kit to clean it up.
    Biggest tip for FM, set max volume of your source to be no louder than your loudness war winner Z-69 Whatever as you hear it on the dial. Then leave that level alone (normalized levels prefered), and use the radio’s volume only.

    1. Interesting you mention bitstreaming – the WT32 includes PCM and SPDIF digitial output on the package. Sadly, the sparkfun breakout board with WT32 already soldered in place doesn’t route these signals out to the headers :(

      Sure, you’re still talking about a compressed audio stream coming in over the bluetooth >.<

    2. Don’t forget that the MP3 decoders on most phones are rubbish (Apple excepted – I hate Apple and all their litigious and market-constraining nonsense, but they surely know how to do AAC/MP3 right).

      Seems to me that what’s really needed is for car manufacturers to give their CUSTOMERS the maximum flexibility they can to allow the CUSTOMERS to find the right solution for their OWN needs, rather than sticking everyone with the same inflexible solution that suits few, even if it did seem like a good idea during that late night in the wine bar.


      Rant over. Sorry. (Not really :)

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