Discuss Hacking the Motorola D650 Bluetooth Dongle to work with the iPhone/iPod Touch at the Hardware - Hackint0sh.org; So - as I'm not the first person to find out, the nifty Motorola S9/D650 ...
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.
Last edited by Numbski; 08-27-2008 at 11:42 PM.
Well, crap. I'm home - I put the D650's circuit board on my scanner, and have a nice TIFF file of the board, and was going to annotate it, but GimpShop is acting up. Ugh.
Okay, along the right-hand side of the board, you'll see 9 test points - the third and fourth are labelled J3 and J2 from the top. The very topmost one is audio ground, corresponding to pins 1 and 2. The second spot is the left audio channel (pin 4). I would then have expected the third spot, J3 to be the right audio channel, or pin 3 - but it isn't. I have no clue what it is, and in fact none of the other solder points show continuity to pin 3. The 4th one, or J2, is also audio ground. The rest I can't seem to trace at the moment.
The good news is that if you solder a speaker, headphone, or whatever to the first 2 test points, you will have a functional test for whether or not the iphone is sending audio out the dock connector or not, so it wasn't a complete waste. I'll try to get that image up as soon as possible.
For the sake of clarity, I made some errors earlier - pins 1 and 2 are audio ground, and 16 should be USB ground, but they're all tied together anyway.
O Audio Ground
O Left Audio Channel
J2 Audio Ground
Last edited by Numbski; 08-27-2008 at 11:45 PM.
At my earliest convenience, I'll try the following:
Pin 2: GND
Pin 3: Right Channel Line Out
Pin 4: Left Channel Line Out
"Pin 11 should have a 1K resistor between it and pin 21, and also a jumper wire from pin 11's end of the resistor to Pin 30 of the dock. I've been using this for awhile and it works fine."
Based on pinouts.ru, 29 and 30 are connected inside the iPod, so in the interest of keeping this whole hack simple:
Connect 11 to 21 using a 1K resistor, which gives us dock mode. Pin 21 is the accessory mode indicator.
Connect pin 11 to 29 or 30 without a resistor. That simply ties the firewire ground to the serial ground. What the point of that is, I have no idea, but hey - I'll try it anyway.
Last edited by Numbski; 08-27-2008 at 11:58 PM.
That failed too. This is driving me nuts. I'm tempted to disconnect the board from the connector and verify that I *can* force audio out.
Okay - I think I need to take a different approach to this. I made a logical error early on. I thought that if I took a resistor, and touched a multimeter to either side of it, that it would pass a continuity test. That assumption was wrong - a 4k resistor I had lying around failed it. So...since these work with the old iPods, clearly the accessory mode for pin 21 *is* already set, but probably to the wrong value.
So the tact I need to take is to trace pin 21, and figure out what value resistor is sitting on it before going to ground, and secondly, figure out *which* ground it runs to. I don't know if a multimeter will work for that. :\ I may just have to do a visual trace. Anyone with a bit more electronics experience feel free to jump in here any time. One would expect to find a 1k resistor, grounded to firewire ground, pin 29 or 30, but who knows - it seems like these 3rd party manufacturers randomly grab whatever ground pin is most convenient, and as you can see from the pinouts.ru diagram, there are many possible options that they could have set.
Also, I know it's hard to tell from the picture, but despite failing continuity test, there does appear to be a trace connecting pins 11 and 15, which would tie serial ground to audio ground, and probably has a resistor somehow in-between that kept my continuity test from succeeding. It would be good to know what value is there as well. Of course, if resistors cause continuity test failures, it's no wonder I couldn't trace out those other test points on the right side of the board!
Last edited by Numbski; 08-28-2008 at 05:19 PM.
After having done some homework, and understanding how to *properly* look for continuity and resistance, I've removed all of the wire and components I soldered on to get a proper reading of the default configuration for this dongle.
What I can say is that the first test point, pin 1, pin 2, and J2 really *are* all the audio ground tied together, showing no resistance at all. So I didn't screw that much up.
Pin 11, which is the serial ground, is not connected at all to audio ground. Pin 15 on the other hand is connected to audio ground with no resistance at all (as it should be from what I can tell).
This is where I start getting into some weirdness.
Pin 13 (serial rx) is shorted to audio ground with 2.8k of resistance. That's probably correct, as it's over serial rx/tx that we see play/track forward/track back happen.
Pin 21 (accessory) is shorted to audio ground with something like 258-265k of resistance. This might be where the iPhone is balking. Per the pinout:
So the D650 is floating in some weird middle ground betwen showing up as a photo import cable, and a serial interface for head units, neither of which is correct. The next step is to locate this "wrong" resistor, and replace it with a 1k resistor and see what happens.
1kOhm - iPod docking station, beeps when connected
10kOhm - Takes some iPods into photo import mode
500kOhm - related to serial communication / used to enable serial communications Used in Dension Ice Link Plus car interface
1MOhm - Belkin auto adaptor, iPod shuts down automatically when power disconnected Connecting pin 21 to ground with a 1MOhm resistor does stop the ipod when power (i.e. Firewire-12V) is cut. Looks to be that when this pin is grounded it closes a switch so that on loss of power the Ipod shuts off. Dock has the same Resister.
Identified more of the right-side test points.
The third one down is pin 6, left channel audio *IN*. That could be useful.
The fourth one down (J3) is pin 8, COMPOSITE VIDEO OUT!!! Even more useful!
The last one appears to have a connection to multiple pins. Pin 28 with 25k resisitance, and pin 16 with 25k resistance. 28 is FireWire Data TPB (+), and 16 is labelled usb ground, but for our purposes, it's audio ground. Measuring between those pins shows a 4.7k resistor. It also appears to be connected to pin 27 with 3k of resistance. :\
Last edited by Numbski; 08-29-2008 at 02:32 AM.
I mis-counted pins earlier. Wha I saw as pin 21 was really pin 19, 12V Firewire power. I have no clue why I saw that with resistance to ground, or why the adapter would short firewire power to ground to begin with, but it does. Pin 21 doesn't appear to be shorted to ground at all, which would be strike 2. Pin 11 needs to be shorted to audio ground (or at least *A* ground), and 21 needs to be grounded with proper resistance.
What confuses me is that this adapter works *AT ALL*. It doesn't make sense. There's nothing there to make an iPod recognize it. Everything that needs to be there, isn't.
I haven't watched the whole thing yet, but Systm did an episode on the iPhone's pinout vs the iPod's. So far I've watched enough to confirm why I'm going so nuts.
Good watch for anyone interested in this sort of thing.
He makes reference to ipod linux's pinout reference in the show:
Last edited by Numbski; 08-29-2008 at 02:09 PM.
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