A Head Unit Docking Station


[Ivan] had a simple idea: being able to control his Android device from the small keypad on his car’s steering column. This would allow him to cycle through apps, navigation, and audio tracks while never taking his hands off the wheel. Feature creep then set in and [Ivan] asked himself how he could charge his phone through the same interface. What he ended up with is a head unit that’s also a dock.

While [Ivan]’s steering wheel doesn’t have the nice integrated remote control buttons found in newer cars, he does have a Blaupunkt remote, a small, clip-on controller that has a an IR transmitter on it. The IR receiver was connected to a PIC microcontroller, sending commands to the phone for up, down, left, right, menu, and home. Audio output from the phone is handled by a small USB sound card connected to a USB hub, sending the audio signals directly into the head unit’s amplifier.

Having the phone charge while it’s still in USB host mode is the crucial part of this build; not being able to charge on a long car ride would quickly drain the battery and make a car dock kind of pointless. To accomplish this, [Ivan] simulated a Galaxy S4 dock with a few resistors in the USB port, allowing the phone to control the USB sound card, listen to the emulated keyboard and mouse, and charge at the same time.

It’s not a pretty build, but it is extraordinarily useful. In the videos you can see that [Ivan] pretty much pulled this build together from stuff he had sitting around – a great reuse of junk, and a great addition to his car at the same time.

22 thoughts on “A Head Unit Docking Station

  1. I do this type of work all day, we use Crestron Systems to link and control everything from small touchscreen as well iPads and iPhone. We build custom luxury tour buses and motor homes.

    1. My friend works for Crestron. Goes on and on about how awesome he thinks it is. Sounds proprietary and expensive and honestly boring. Not that I’ve done any research into them at all.

  2. Hands on the wheel, eyes on what? Most buttons need eyes to see results, but as a driver you are blind to all the distractions you have introduced in inside your car. Or, it’s the other way around. In a millisecond, and it takes t…..i…..m……e to press buttons and see results. Can’t a raspi do voice?
    It’s time for voice only. Command control. No visual response given.
    This, instead of video game playing behind the wheel. Please.

    1. You don’t need to look to press buttons. Unless you have a prosthesis you can feel where your thumb is and press the appropriate button. That’s why he isn’t just touching his screen.

      Once you are familiar with the locations of the buttons you’ll never need to look again.

      1. The phone is not out of sight, therefore it is being looked at. Buttons or voice no problem, just hide the screen while driving. No visuals! Attach nothing to the windshield.
        You are guna look at that sucker and BAM!

        1. Bet that phone is being used for GPS.
          And a automobile is a noisy environment so speech direction or commands is bullshit unless you own a ridiculously expensive (and often also boring to drive) vehicle that is completely sound insulated from the environment outside of the cabin.

          You can dream and demand all you want, but speech control and responce of accessories in a car is never gonna take off and become mainstream and common.

  3. It can be interesting to use cassette tray as phone dock. Thinking about it with my Audi Gamma’s III. There are a lot of fans of youngtimer cars, and most of them want old original radio with nowdays features. So far I’m on this road and have some success with pin-to-pin replacement of radio’s CPU with PIC18F2550 module. This gives me ability to fully control every piece of radio (including display and frequency synthesizer) over USB. Looks like this: http://www.stanson.ch/files/Audi/AudiGammaIII/processor1.jpg works like a charm. Without USB control radio works as original radio using PIC as processor for tuning, buttons etc. Marsboard (clone of Cubieboard, but with adequate connectors layout) with Linux on board can get control and do anything, including playing stored music. Still thinking about docking the phone into cassette tray.

      1. What are you interesting in? It’s under development, but at least I can publish CPU module schematic, PCB layout and some unfinished code. However it’s highly radio dependent and all that stuff is useful only for Audi Gamma III (M327 Blaupunkt AUZ1Z3).

        1. not interested in the ” I want to copy you ” sence, but more the general execution of the project, how did you reverse the origional micro to replicate function etc. if you haven’t wrote about it dont loose any sleep over it on my count, I know I almost never document my projects so would have a cheek asking others to do the same!! but if you have a blog/website/ forum share the link please ;)

          1. Nearly all functions written from the scratch, looking into IC’s PDF’s (freq synth, mostly) and schematic of radio. Only one thing I really reverse engineered was custom display – I just use oscilloscope to view how many bits original CPU sends to LCD over serial bus and then play with that bits in stream to find out bit-segment connections. Really most of things documented in plain text and circuits, so I’ll put them to my site here: http://www.stanson.ch/index.php?page=files&dir=Audi/AudiGammaIII

            I thought than nobody will be interested in such highly specific modification, because it is applicable only to Blaupunkt Audi/VW Gamma III M327 and may be to the Audi Delta II M330 which use nearly same hybrid ceramic CPU.

        2. I’d also love to see the writeup!
          I got an old Verona SQR029 or something from Audi also – seems the easiest way is to leave the old processor and switch the LCD to my own µc when starting the mp3 player (if switching at all – the screen is almost useless). You could also use this system to control the parking gates or to display live data from the engine (if you have any) – could be handy.

    1. Neat idea, but how would you address making it universal to whatever phone you have? My iPhone would definitely fit in a cassette space, but my android phones would not.

      I had thought of the idea of simply turning the radio bay into a dock for a tablet or phone, with amp and all that good stuff.

      1. I have Nokia N9, it’s nicely fit into cassette tray. As for universal dock – it’s nearly impossible, because of different connections on different phones, even if they fit into tray. However, it’s possible to have replaceable pcb with connector/connectors for the phone, so, if you change the phone to one that still fit into tray, you will have to replace pcb with connectors only.

  4. Not a fan of touch screen controls. I like being able to control everything on the dashboard without changing focus from the road because the buttons and levers are tactile. To each their own though :)

  5. The Galaxy S4 has a S-Voice apps that do voice commands like “Hi Galaxy, play next song”, so although this looks like a nice hack, it’s a bit of a retro step.

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