Nexus 7 Car Integration Project

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My car is a Subaru, a 2002 WRX which I bought in 2009. The factory equipped this car with a 6-CD-changing, cassette-playing, double-DIN head unit which was still installed when I bought it, and remained in the car until February 2014, when I finally decided it was time to upgrade to something more…21st century. To make a long story short, and spare you a bunch of rambling, I decided that I wanted to integrate a Nexus 7 tablet into my car rather than buy some fancy double-DIN head unit with an LCD and a DVD player which would cost $1,000 and which wouldn’t really make me happy. The Nexus 7 (2013 version) is an Android tablet manufactured by Asus with a 7″ screen (151 x 94 mm). The screen fits pretty much perfectly within the window of a double-DIN head unit. As of this writing, the version with 16 GB storage (vs 32 GB) with wifi-only (no 3G/LTE) is currently available on Amazon.com for about $200. It’s an ideal candidate for integration into the dash of a car, if you’re interested in Android over iOS or Windows and aren’t looking to spend a thousand bucks.

Lead-up to the project

Before starting on this project, I did a considerable amount of research. I’m not the first guy who’s tried to mount a tablet in his car. There are several ways that people have approached this problem, but in general, there seem to be two common approaches. The first approach (example) is to fully integrate the tablet into the car’s dash. The back of the tablet is often removed and the power and volume buttons are wired to other buttons that exist in the car, usually remnants from the stock stereo system. The tablet is sometimes connected via USB to a powered USB OTG hub, which in turn is connected to a digital-to-analog converter (to feed to the stereo amplifier) plus other gadgets. Benefits:

  • These installs are elegant, and look and feel like an off-the-shelf head unit with a 1080p screen running Android has been installed in the car. Seamless.
  • You can have as many USB devices as you like. Storage, radio, backup camera, etc.

Drawbacks:

  • The tablet cannot be easily removed from the car. This presents a theft risk, and makes the tablet useless for anything else. Also, extreme temperatures are not good for the battery, and even in temperate Seattle, it always dips well below freezing during the winter and the inside of the car will get extremely hot during the summer.
  • This approach seemed pretty difficult compared to the second approach, initially.

The second approach is to mount the N7 to the dash using magnets or some other mechanical means and interface it with the car totally wirelessly (example). A bluetooth system such as a Novero TheTrulyOne is installed which interfaces with the stock head unit. An inductive charger is mounted behind the N7. The USB and headphone ports are not used. Benefits:

  • The N7 can be easily removed and used like a regular tablet while you’re not in the car. This is great anti-theft protection and means you don’t have to buy a second N7 to replace it.
  • You also get all the normal features of the bluetooth system (hands-free phone calls in the car).
  • There is minimal wiring required, just installing the bluetooth system.
  • By preserving the stock head unit, you can potentially throw the N7 in the glovebox and use the old head unit when you want to listen to the radio or play a CD.

Drawbacks:

  • No USB hub means no suite of gadgets behind the dash to augment the tablet.
  • Making the install look clean and professional could be much more difficult. Do you mount the tablet over the head unit and obscure it? Mount it up high on the dash and leave the stock head unit alone? In my car, there’s not a clear way of doing this elegantly.

In the end, I decided to follow a path more closely-aligned with the first approach, but which also shares some of the benefits of the second approach.

My vision

  • Nexus 7 permanently installed in my dash, in the same place where the stock double-DIN 6-CD changer head unit was installed.
  • An aftermarket single-DIN head unit installed on top of the dash, using a mount which is commercially available that replaces the clock pod that comes with my car. My clock has been dead since the day I bought the car, and I’m happy to replace the useless clock mount with a new mount that holds a single-DIN head unit.
  • Tablet connects to the head unit via bluetooth, and the head unit then channels the audio signal to the stock amplifier.
  • Tablet connects to my cell phone (Nexus 5) via bluetooth automatically for internet access.
  • Use services such as Pandora and Spotify for music, Google Maps for GPS/navigation, and the head unit for AM/FM radio and CD player functionality.
  • Protect for the eventual addition of a USB hub so that I can add USB devices such as USB storage keys or a backup cam.
  • Remove the front face of stock double-DIN head unit and make it into a facade plate which can be placed over the tablet’s screen as an anti-theft measure. Thief peeks in the window, sees what looks like a stock 6-CD changer with a cassette slot, decides my car isn’t worth the time/risk to break into.

With the plan established, I set to work building a bill of materials and sketching up plans on how to integrate everything into a coherent, professional end product. Along the way, I documented everything, which I will attempt to share here on this blog.

Project Goals

  • Tablet seamlessly integrated with the car – a stranger would think it was a professional installation
    • Visually flawless
    • Integrates with the car stereo without any perceptible degradation of sound quality and without having to take unreasonable extra steps every time I get in the car to make it work
    • Requires no regular maintenance/attention to keep it working
  • Internet access via tethering to my phone in my pocket, without me having to ever take my phone out of my pocket when I get in the car – must be fully automatic
  • Preserve ability to listen to CDs and radio easily
  • Theft-resistant if possible, and in the case of theft, does not burn me – thief doesn’t end up with access to all my password-protected accounts. Reduce risk of identity theft.

I have documented the various aspects of this project in a series of posts.

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