Plaidophile

Tonight I decided to finally see if I could trick the player into giving me a bare aux input, for the iPod.

(Short answer: No I couldn't.)

Before doing any of this I exhaustively researched the problem online, finding that basically nobody had any clue about how to do this, except Dension, but their Panasonic icePod module will be $150 if it ever comes out (so far, it hasn't). Since for that price I could get a new stereo with a real aux input, I didn't consider this to be a viable option. (So what if I can control the iPod from the stereo? The iPod's interface is better! That's wh I'm getting an iPod! I mean, duh...)

First, after removing the player from my car, I hooked it up to a 12V power supply (- to ground, + to battery and accessory) and turned it on. It happily sat there, mute.

Next, I measured the various voltages coming off of the changer port, after (correctly) guessing that the center pin was ground. They were all 12V or 5V. So I tried shorting each ground to each pin, hoping that one of them was simply a "device present" pin.

It wasn't.

So I looked around online some more, following way more dead ends than I wanted to, until I came across a Panasonic CD Changer Emulator, which had the pinout, and a brief high-level description of how to program a PIC to do exactly what I wanted.

Only, two problems:

• I don't have a PIC programmer (well, I do somewhere, but it's parallel-port based and untested and I don't know if I can still get the software for it)
• The bill of materials for this would exceed $30, the cost of an iTrip at CompUSA, which is somewhat more flexible than a cable-based setup anyway.

First I tried tricking the player into thinking there was a CD changer connected by bridging the data send to the data receive port. This didn't work.

Then I tried bridging ground with the two mysterious "ACC" pins. This didn't work.

Then I tried bridging ground with the clock, strobe, and data lines (not all at once). None of those worked either.

Then I realized that the presence is probably detected by the 125KHz clock signal. So all I needed was a 125KHz square wave generator! Google had plenty of links. Of course, then we run into the whole "bill of materials" problem again (Radio Shack doesn't carry the specialized op-amps, inductors, etc. which most of those need, so that means special-ordering from DigiKey or National Semiconductor or whatever), and it could be argued that since my time is worth $25/hour, spending more than an hour on this (which I'd already exceeded by this point) just wasn't worth the opportunity cost and I should just buy an iTrip. (Which is a bullshit argument, of course, but I have to justify my laziness somehow.) And even then, getting a valid clock signal still wouldn't ensure that the player will actually turn on the simple RCA input.

Then I tried opening the player up to see if there were any hidden jumpers or service switches or anything inside. I found none.

I started to wonder how much a cheap in-dash FM-only head unit with aux input would run.

Then I just decided I'd get an iTrip, put my car back together, and called it a day night.

I do have a signal generator in storage which I could use to test the 125KHz theory, but right now I'm feeling pretty apathetic to the whole thing. :)