Hacking the Motorola D650 Bluetooth Dongle to work with the iPhone/iPod Touch
So - as I'm not the first person to find out, the nifty Motorola S9/D650 bundle that Target sells won't work with the iPhone, because the dongle doesn't work. Bummer.
The question is, why? Seriously. So being the hacking type, I wanted to know. (pictures to follow, btw - I'm at the office).
So I went about cracking one of the two D650's that were in the package (don't know if that's typical or not...) open, which was tricky. There are two plastic pieces that are snapped together. Don't bother pulling the label off - there aren't any screws under there. The best way to get the thing open is an exacto knife or jeweler's screwdriver right next to the dock connector and gently (as reasonable) pry it open. It will snap pretty good, and there was a *small* amount of plastic that broke, but would be easily fixable upon closing the case up again, so no worries.
The circuit board is very straightforward. The whole thing is basically an audio line-out adapter, and a bluetooth chip that takes that line-level audio, and converts it to A2DP for you, along with serial commands, etc.
So here's where I am: the dongle *can* work. I have a Sony one that I'm going to open for comparison's sake, but in short there's no reason it shouldn't. The first thing I checked was that the ground used for audio line out (pins 1, 2, 15, and 16) were tied to the ground for serial data (pin 11) per the following thread:
Apparently, in order to get audio-out on the iphone, you have to trigger it into a very specific accessory mode. You'll know you're part of the way there, because you'll get the prompt about putting the phone into airplane mode. Out of the box, you won't get this prompt, and as I suspected, 11 and 15 didn't show continuity, so I soldered a piece of wrapping wire to pins 11 and 15 (one side of the board is odd pins, the other is even). Once I did that, THEN I got the airplane mode prompt, but much to my surprise, no audio out - it continued playing audio out of the built-in speakers.
This leads me to believe that elsewhere on the board, it's playing with the serial pins for the AVRCP stuff (play, track forward, track back). I haven't dug into that yet, but I wanted to get this out there before I forgot what I'd done so far. OH! BTW - there are 5 nicely placed solder points off the to the right of the board, and I've already confirmed the first one is the ground for audio line out (pins 1, 2, 15, 16), giving us a nice point to work from. I'm betting that audio L and audio R are two of the others, but I don't want to get too far ahead of myself. Ideally, a D650 could be turned into a multi-purpose pocket dock, with mini-usb for charging/docking while listening to your music, and even a 1/8" minijack for plugging into non-bluetooth sound systems. I'm figuring that the S9 bundle, if it really does always come with 2 D650's, would then become one heck of a value. I just need to figure out what is failing to trip the iphone into audio line-out mode and fix it. Suggestions are welcome.