Reverse-engineered LIN bus notes for Audi MLB evo platform cars (B9 A4 / A5 / Q5 / Q7). Frame maps, byte/bit positions, checksum and CRC algorithms, connection scheme — no firmware, no hardware.
Bench rig used for every capture in this repo · click the right-hand frame for the 30 s demo
| Node | Document | What is in it |
|---|---|---|
| E791 — center console switch panel | e791-switch-panel/README.md |
Node role, bus parameters, button / LED name map, PID summary |
e791-switch-panel/connection.md |
Wiring diagram, T54c / T5e pinout, connector part numbers | |
e791-switch-panel/protocol.md |
PID 0x64 / 0x61 / 0x3C / 0xE2 byte.bit maps, verified frame examples, unknowns |
|
e791-switch-panel/rolling-counter.md |
Rolling counter and its coupling to the CRC | |
e791-switch-panel/res/ |
Images — wiring excerpt, connector photos, button map, bench rig |
More nodes get their own folder as they are captured.
The data came out of building a man-in-the-middle board that sits in-line on this LIN segment, between the J519 BCM and the switch panel. It keeps Start/Stop off by default — including when the car switches to the Efficiency drive select mode and re-enables it — and adds a long-press on two stock buttons to trigger a garage door remote. The board and its firmware are not published here; only the protocol is.
- Demo (vertical): https://youtu.be/Rxn6-zExhTo
- Build article (RU): https://www.drive2.ru/l/733513345021248551/
Other people's LIN reverse engineering — different modules and different cars, listed for anyone searching.
| Link | Note |
|---|---|
| https://github.com/zapta/linbus | LIN gateway project — the original inspiration for this build |
| https://openinverter.org/forum/viewtopic.php?t=3152 | VAG LIN thread |
| https://web.archive.org/web/20241005094756/https://blog.dietmann.org/?p=324 | LIN sniffing writeup (archived) |
Derived from passive bus observation on one car, unofficial, no warranty — use at your own risk.
LICENSE and the human-readable deed.
Reuse is free, including commercially. Two conditions: credit the source, and keep derivatives of these
documents under the same license.
Credit block, copy-paste as-is:
LIN protocol data for Audi MLB evo E791 switch panel
by Andrei Yablonski — https://github.com/wiskiw/audi-mlb-evo-lin
CC BY-SA 4.0
Using this in a project, post, video or firmware? Credit the repo and link back.
Questions or anything that needs a different arrangement: @wiskiw.