Perhaps a perfect solution for the steering wheel controls and much more
I have a new VW Jetta TDI and I am very excited to start modding it up!
I am thinking of putting in a carputer for the fun of it and because it is just cool and a challenge. However, one of the hard things was figuring out how to make use of the steering wheel controls on the computer. However, I think I cam across a GREAT solution that requires almost no hacking to the car. My rule was that I want to be able to keep this thing as close to stock as possible and be able to put the old stuff back in without trouble.
Here's what I found: pac-audio makes a product called pac-can (I'm sure you have heard of it). It reads the steering wheel controls and you can then use that in conjunction with another unit to make them work with aftermarket radios. At first, I was deterred from the product because it said you have to use it with one of their other products to make it work. However, when I looked at the input diagrams for the other products, i realized that this was nothing more than a voltage source that varied an analog signal according to what button was pressed. Those of you in the know should recognize this as an "emulator" for the old resistance based 2 wire controls (why the heck did they ever move away from those things anyhow?). Basically, this thing reads the CAN-BUS and when it detects the right code, it outputs a voltage. The value of the voltage is supposed to be the same as if it were an old car with a voltage divider circuit.
At any rate, I called pac-audio and they confirmed my suspicions. It does indeed output a different voltage for every steering wheel button and better yet, it is functions in the 0-5V range. Does anybody know what that means? You guessed it, direct input to the Phidgets 8/8/8!!! No signal conditioning required!!! Just put this directly into one of the analog inputs and you have a way into the computer.
Now, if you have some experience with Phidgets on the forums, you will thank Zorro for making our lives extremely easy from here. Check the following post:
Now what's cool is that Zorro has written a plugin that allows you to I/O directly from the centrafuse head! That means you can read the values output directly from the SWI-CAN and control any function you want in Centrafuse. Follow the link to a post by Zorro that explains how to rig up an input from a sony controller. The only difference here would be that you would directly connect the SWI-CAN in place of the custom input cable and you would probably have to figure out what values (ie: the 9xx values in his code) correspond to the input voltage reading.
Vuala! No wire cutting, no hacking, just sweet interface baby!
I am going to be putting in my carputer in the next month or so and I DEFINITELY plan on making this mod. The other cool thing is that you can write your own scripts withing Zorro's plugin so you can write your own custom interface in centrafuse and do all kinds of great stuff like make your windows go up and down, honk your horn, read cabin temps, make it tell you that your sexy... anything you can think of you can do it right from centrafuse now.
I am pumped about this! and I'll let you know how it turns out!