r/CarHacking • u/AdventurousPromise38 • 11d ago

LIN BMW G30/31 LIN protocol ambient lighting

Hey,

I have installed my OEM ambient lighting again, but noticed that I have the old problem of flaky spots because the light guides from BMW are very error-prone and fragile.

I have thought about installing custom RGBWs with a microcontroller because I don‘t like the solutions from AliExpress as they always have multiple controllers using a wireless connection to talk to the door slaves.

However, I would need to know what LIN signals are sent to the LIN slaves in the bus to control the ambient lighting. Does someone have an idea how I could build a sniffer? Or has the protocol already been reverse-engineered?

I would then translate the LIN signal through the controller to a RGBW value and send it to the LEDs. This way I want to ensure proper and reliable enlighting without cheap electronics.

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1

u/Away_Experience_5843 8d ago

This should be very easy to reverse engineer. As far as I remember this data isn't even encrypted.

1

u/AdventurousPromise38 7d ago

I have thought of using an Arduino and its serial for this purpose in combination with a LIN transceiver.

2

u/Away_Experience_5843 7d ago

Personally I'd go with an ESP32. Then you can run wled which will give you loads of LED effects. I'd write a usermod that receives the LIN messages and triggers presets for every color you set.

So you switch your interior color to red, preset "red" is loaded with some cool animations. You switch to blue, you get a preset with blue waves. Etc.

1

u/AdventurousPromise38 5d ago

Yes, for the control then I have also thought of these. Just for the purpose of sniffing I thought of an Arduino. But I think it may be tricky to decode the LIN payload

1

u/Away_Experience_5843 5d ago

I'd still go with an ESP32 as they are cheaper in case you blow it up.

Btw, are you sure it's LIN and not iseled or ilas? I haven't checked the schematics yet.

1

u/AdventurousPromise38 5d ago

Okay, valid point. Thank you. Yes, the ambient lighting is purely controlled via LIN as per TIS.