tree-sitter-dbc

A tree-sitter grammar for CAN DBC files

DBC Files

DBC files describe the nodes, messages, signals, and other signal data of a CAN bus. Since CAN is not a self-describing protocol DBCs are necessary to decode the information broadcast on a bus. More information is available in CSS Electronics' excellent guide (as well as their many other well-written guides on adjacent technologies).

The CAN DBC specification was written and published by Vector Informatik GmbH. The most recent version is 1.0.5, published in 2008. A PDF of the specification is available from Vector's website.

Errata

The specification contains two ambiguities. Since DBCs have been in reliable use for two decades these are trivial for the actual use of the files but writing a grammar reveals them.

• Section 8.2, pg 5-6: There is no specification for the multiplexer_switch_value. This is referred to in multiplexing but is not defined. I am assuming it maps to an unsigned_integer, as multiplexers are usually treated as simple enumerations without an engineering conversion that would make them signed or floats.

• Section 8.3, pg 7: Strictly speaking the specification only allows a single signal_extended_value_type_list item that sets only one signal type. I believe this is an oversight that has been a non-issue due to this feature being essentially deprecated. I've added an undocumented parse object to iterate through a series of SIG_VALTYPE_ declarations. This aligns with the rest of the top-level declarations and makes the parser more robust. If this can be confirmed to be in error please reach out to me or put in a PR to remove it.

Bindings

• C
• Go
• Node
• Python
• Rust
• Swift
• Zig