Sunday, July 06, 2008

Continuing my iPhone tests

To say that there is a lack of peripheral devices for the iPhone would be a gigantic understatement. There's shelves and shelves of iPod accessories, but even a year after it's launch, there's still virtually no iPhone approved accessories that allow you to listen to music without GSM buzz. In my car I resorted to using a Belkin Tunebase II.


On the upside, it gives me a mount for the iPhone, it charges the iPhone, and it has a powerful FM modulator. On the downside, the mount gets a bit saggy after a while, and the FM modulator picks up all the GSM buzz from the phone every time you get email, a text, a call or change cell towers. It's not the ideal solution. Of course, it doesn't allow hands-free phone usage in the cradle unless you're wearing a bluetooth earpiece or have some other secondary bluetooth device hooked up.

The Tunebase does have a stereo line out option, so I ran a line between my car stereo and the line out to forego the FM modulation. This did put an end to the GSM buzz, but added a new engine whine in its place. Also, the sound quality is still as bad as FM modulation.

I had an old Kensington FM transmitter that didn't work worth crap, so I decided to hack that up and see if I couldn't splice together a direct connection from the stereo to the iPhone. Then I could get rid of the tunebase altogether and fabricate a more secure mount a little closer to the steering wheel, so that reading Google maps wouldn't be such an eye strain.

Unfortunately, nowhere online does it seem to have details of what wires are what on the iPhone cable. Apparently this is Apple's proprietary knowledge that is only shared with manufacturers licensing the tech for their products.

Here's what I set up to test it.


I ran two jumpers from a stereo cable plugged into a guitar amplifier and checked each wire coming from the iPhone.

Here's the wires I had to test.


This was a quick and easy way to find the music +/- wires. Just make sure and test every combo because I found if you had the + from the left channel and the - from the right, you'd still get music, but it was very quiet compared to the correct combo.

I can't tell you whether all cables will have the same colored wires inside, but in this particular cable I found:

Left channel
White Music +
Yellow Music -

Right channel
Green Music +
Blue Music -

Now the brown wire is also a music ground of some sort, but I can't quite figure out where it fits in to the big picture. It might be the video ground? Here's my other trouble, I can't figure out the power combination. Seems like Red would be power + and black would be power -, right? Well, I hooked those leads up to a 12 volt power outlet, but the iPhone didn't indicate charging. Then I tried the other black wire as ground. Still no indicator. Then I tried both black wires -- still nothing. Then I tried brown. I didn't get a charge indicator, but it killed the music, so I know that wasn't right.

If I had more money, I'd buy and dissect more products because I know if I bought an actual iPhone cable I'd also find wires for video, and obviously there's some sort of data line. I was hoping I'd find a simple mic-in line for the iPhone, but that doesn't seem to be there either. I know it's possible to add a mic since people make recorders that plug into various other iPods. I just don't know how to tell the iPhone to read an external mic as the telephone mic or if that's even possible.

Here's the only solution I've found to integrating the iPhone into my car stereo's non-bluetooth hands free system.


This is a shielded camcorder cable. Normally you have left/right music and a video line, but in the case of the iPhone, you can plug it into the headphone jack and get left/right music and a mic input. (Notice the adapter for the recessed headphone jack. That's a pain in the ass.)

By the way, when you have something connected to the line out of the iPhone and recieve a call, it mutes your music, but doesn't play the telephone audio through the line out. If you have something plugged into the stereo jack, that supercedes the line out. You can't have both plugged in and play music through both. If you're plugged into the headphone jack and you receive a call, it mutes the music and plays the phone audio through whatever is plugged into the headphone jack.

Long story short, if you want to use a wired hands-free system like the one in my car, you've got to plug into the headphone jack with a camcorder cable. You'll also have to run a seperate line to the base of the iPhone if you want power. There's also a phone call mute wire that runs from my stereo to the phone hook-up, which will mute the radio/CD player if you get a call, but I have no clue which wire in the iPod cable that would go to.

So that's where I'm at. As I have time, I'll keep testing and report back.
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