[alexwhittemore]

I've got an iPhone plugged in via Y cable. This is cool. I can browse my iPod app contents on the headunit, but I can also play whatever third-party app I like (soundcloud, rdio, spotify, whatever) and A) steering wheel skip buttons still work, and B) the headunit displays the song.

This is cool. I like this.

The problem is, I just got a Nexus 7 and I'm working on a full-out integration. First part is audio.

The iPhone uses iPod Accessory Protocol running over a serial connection (this is the point of the Y cable, it has translation hardware). The serial connection handles commands for controlling playback and track info, while audio itself happens all in analog, dock connector to aux in.

The nexus, when plugged in, works via MTP. I can browse the filesystem in the headunit and select any downloaded songs, but sadly this is still not USB streaming audio class - I don't hear system audio (app output like navigation, streaming apps like rdio or spotify, etc) via the car. I can only play files.

Unfortunately, I'd don't think I'm missing anything, but hopefully I am - if you have an android phone or tablet, how do you connect it to listen to music?

Assuming that's correct and that there's no way to get streaming system audio via OEM means, I'm afraid the next best solution may be to design some custom bluetooth hardware that does a full on translation of iPod Accessory Protocol to the bluetooth equivalents, basically spoofing an iPhone. Pair your device to this hardware sitting on the end of the Y cable, and it behaves just like a normal iPod plugged in, except everything's going over bluetooth. I believe this is possible, and would be a good solution for both iDevice users and android users.

The final thing I'm planning on is some custom hardware to interface to the car's CAN busses and some custom software to control that, perhaps also remotely. So for example, you could log in via a mobile app and unlock the doors, roll down the windows, etc etc.