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f89ae1e Toyota Highlander and Avalon DBC (#93) b916787 add back import file for honda pedal's (#94) d6d0700 Updated README with a recommended overview 698d464 Cadillac: lkas clarification 329eca4 some adjustments in cadillac dbc 76f91ba Cadillac: lkas mode added de6929e Cadillac: added ASCM-b lkas control msg 0619ec6 checksum seems only 10 bits 87bb746 Cadillac: updated vehicle speed factor cdfae2e Cadillac: forgot to update old references to msg 384 0a804b0 Cadillac CT6: fixed LKAS msg 552089c Cadillac CT6: added LKAS cmd msg. Thanks mutley 4b64095 added cadillac dbc, starting from Volt 07a6e3b Toyota: forgot to add _comma.dbc 8521c6a GM: reordered msg addrs so they are monotonic 6a3b268 Ford Fusion: added brake and doors info 971e9f1 Ford Fusion: added VAL and CM regarding Lkas_Action signal git-subtree-dir: opendbc git-subtree-split: f89ae1e00aed01157a99b4a3a95472c44167f77c
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opendbc
The project to democratize access to the decoder ring of your car.
DBC file basics
A DBC file encodes, in a humanly readable way, the information needed to understand a vehicle's CAN bus traffic. A vehicle might have multiple CAN buses and every CAN bus is represented by its own dbc file. Wondering what's the DBC file format? Here and Here a couple of good overviews.
How to start reverse engineering cars
opendbc is integrated with cabana.
Use panda to connect your car to a computer.
DBC file preprocessor
DBC files for different models of the same brand have a lot of overlap. Therefore, we wrote a preprocessor to create DBC files from a brand DBC file and a model specific DBC file. The source DBC files can be found in the generator folder. After changing one of the files run the generator.py script to regenerate the output files. These output files will be placed in the root of the opendbc repository and are suffixed by _generated.
Good practices for contributing to opendbc
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Comments: the best way to store comments is to add them directly to the DBC files. For example:
CM_ SG_ 490 LONG_ACCEL "wheel speed derivative, noisy and zero snapping";is a comment that refers to signal
LONG_ACCELin message490. Using comments is highly recommended, especially for doubts and uncertainties. cabana can easily display/add/edit comments to signals and messages. -
Units: when applicable, it's recommended to convert signals into physical units, by using a proper signal factor. Using a SI unit is preferred, unless a non-SI unit rounds the signal factor much better. For example:
SG_ VEHICLE_SPEED : 7|15@0+ (0.00278,0) [0|70] "m/s" PCMis better than:
SG_ VEHICLE_SPEED : 7|15@0+ (0.00620,0) [0|115] "mph" PCMHowever, the cleanest option is really:
SG_ VEHICLE_SPEED : 7|15@0+ (0.01,0) [0|250] "kph" PCM -
Signal's size: always use the smallest amount of bits possible. For example, let's say I'm reverse engineering the gas pedal position and I've determined that it's in a 3 bytes message. For 0% pedal position I read a message value of
0x00 0x00 0x00, while for 100% of pedal position I read0x64 0x00 0x00: clearly, the gas pedal position is within the first byte of the message and I might be tempted to define the signalGAS_POSas:SG_ GAS_POS : 7|8@0+ (1,0) [0|100] "%" PCMHowever, I can't be sure that the very first bit of the message is referred to the pedal position: I haven't seen it changing! Therefore, a safer way of defining the signal is:
SG_ GAS_POS : 6|7@0+ (1,0) [0|100] "%" PCMwhich leaves the first bit unallocated. This prevents from very erroneous reading of the gas pedal position, in case the first bit is indeed used for something else.