How to hook into car status (OBD-II?)

[jwatte]

I'd like to add some underglow. I'd like it to match the car's color, and to be reactive to whether the car is stationary, or moving. (This can be done legally in California if you're careful about how)
My current theory is to get an RGB LED underglow kit like https://amzn.to/44qjCVy and figure out which LED control signal it uses (there's only three main ones) and program my own microcontroller to set the animation/lighting. That is all home turf for me, but car integrations is less known.

But, how do I get telemetry out of the car? A system like OpenPilot uses a J533 harness for integrating with Audi e-tron -- does the Porsche PPE platform use the same? Or can I get this data from the OBD-II port? Is there a good publicly available service manual for these? (Maybe on the NHTSA website?)
Also, where would be a good, easily accessible place to draw power? I'd probably need 12V/5A, and ideally it's switched with main ignition so it turns off when the car locks.

And has anyone done this already and written it up, saving me some reverse engineering trouble?

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[jwatte]

Research so far:
- I can probably get velocity through OBD-II using standard protocols.
- There's a surprising amount of power available in that connector -- these LEDs only need < 15W, so I could conceivable power the entire thing off there.
- The format of the LED strip I got is the standard WS2815B.
- There's a chance there's a J553 VAG connector with access to multiple CAN busses, but I'd rather use the OBD connector for lower risk of interfering with more critical busses.

 

[krissrock]

Idk if anyone has found a switched fuse outside the plug in the trunk

 

[jwatte]

I've decided to bake my own switch into the wiring, because I'm adding my own microcontroller for the light control anyway.

In other news: the lights I purchased seem to gang up 3 at a time. So, I can only control each group of 3 as one light/color. Not a big deal for me, as all of this lighting will be indirect bounce from the bottom anyway.

Separately, I wonder if I can read the blinker stalk or blinker lights from the OBD-II, or if I need to go J-533 for that? It'd be nice to add orange blinker indication ...

A have an OBD-II pigtail harness coming in the mail, so we'll see what can be found out... not a lot of specific info about this model online yet, so I'm on the bleeding edge!

 

[jwatte]

I've done some more research, and the news is pretty bleak :-(

The ICE Macan uses the J533 setup, which has pretty reasonable support from open source projects like the OpenPilot/Comma driver assist system.
However, The EV Macan uses a totally new communication system, developed by CARIAD, which uses gigabit Ethernet as well as CAN, and adds encryption, which has not been open sourced.
Additionally, because the vehicle doesn't have an ICE engine, it doesn't need to supply the regular OBD-II data that emissions testing facilities would use.

I may have to add an accelerometer sensor to my system to detect acceleration/braking, and it seems hard to tie into blinker status without directly tapping the blinker lights somehow, which is probably a bridge too far for this project...

Here's hoping I can find a switched 12V wire somewhere, though. Still doing research!

 

[craz8]

OBD Pin 1 I believe is switched for Porsche cars. This is what my Dashcam installer would have used if we couldn't use the prewiring in the overhead console.

 

[jwatte]

OBD Pin 1 I believe is switched for Porsche cars.

It's good to know they at least kept this VW standard
I wonder if I can pull two amps on that pin?

 

[jwatte]

FWIW I've given up on reactive lights for now; the architecture here is too different and there's too little information publicly available.

I did rent a lift and run the lights underneath the car this week-end, though!

The dark phase of the animation is too dark, so I'll have to fix it. It hooks into the rear left trunk fuse box, but I'm not sure I have an aux switched circuit yet, so I'll keep probing.

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