A lightweight DBC file parser and C code generator for CAN bus message decoding.

Vera is a code generation tool that parses DBC (Database Container) files and generates C source code for decoding CAN (Controller Area Network) bus messages. It simplifies the process of implementing CAN message decoders in embedded systems by automating the conversion of message definitions into efficient C code.

• DBC Parsing: Reads and parses DBC files containing CAN message and signal definitions
• C Code Generation: Generates header (.h) and source (.c) files with decoding functions
• Type Safety: Generates strongly-typed structures for messages and signals
• MQTT Topic Mapping: Supports defining MQTT topics per signal using TP_ instruction
• Signal Decoding: Handles various signal properties including:
  • Little-endian byte ordering (only little-endian is currently supported)
  • Signed/unsigned values
  • Scaling factors and offsets
  • Min/max validation
  • Units

• Go 1.25.1 or later

git clone https://github.com/ApexCorse/vera.git
cd vera
go install github.com/ApexCorse/vera/cmd/vera

vera [options] <build_path>

• -f <file>: Path to the DBC file (default: config.dbc)

• <build_path>: Directory where the generated C files will be created

# Generate C code from a DBC file
vera -f network.dbc ./output

# This creates:
# - output/vera.h (header file with type definitions)
# - output/vera.c (source file with decoding functions)

Vera expects DBC files with the following format:

BO_ <message_id> <message_name>: <dlc> <transmitter>
    SG_ <signal_name> : <start_byte>|<length>@<endianness><sign>(<integer_figures>,<decimal_figures>) (<factor>,<offset>) [<min>|<max>] "<unit>" <receivers>
TP_ <signal_name> <mqtt_topic>

Note: DLC (Data Length Code), Start Byte, and Length are all expressed in bytes.

Note: Receivers are currently parsed but not used in code generation.

Note: The (<integer_figures>,<decimal_figures>) parameter is optional and specifies the fixed number of digits for both integer and decimal parts of the signal value when displayed. If omitted, no specific formatting is enforced.

Note: The TP_ instruction is used to associate an MQTT topic with a specific signal (referenced by <signal_name>). It is placed at the same level as BO_ instructions, not indented under them.

BO_ 123 EngineSpeed: 6 Engine
    SG_ EngineSpeed : 0|4@1+ (0.1,0) [0|8000] "RPM" DriverGateway
    SG_ BatteryTemperature : 4|2@1+(12,4) (1,0) [0|8000] "ºC" DriverGateway
TP_ EngineSpeed vehicle/engine/speed
TP_ BatteryTemperature vehicle/battery/temperature

The generated C code provides:

• Type definitions for CAN frames, messages, and signals
• Decoding functions that extract and convert signal values from raw CAN data
• Error handling for allocation failures and out-of-bounds values

#include "vera.h"

vera_can_rx_frame_t frame = {
    .id = 0x7B,
    .dlc = 6,
    .data = {0x10, 0x20, 0x30, 0x40, 0x50, 0x60}
};

vera_decoding_result_t result;
vera_err_t err = vera_decode_can_frame(&frame, &result);

if (err == vera_err_ok) {
    for (int i = 0; i < result.n_signals; i++) {
        printf("Signal: %s = %.2f %s\n",
               result.decoded_signals[i].name,
               result.decoded_signals[i].value,
               result.decoded_signals[i].unit);
    }
    free(result.decoded_signals);
}

go test ./...

.
├── README.md
├── cmd/                  # Command-line interface
│   └── vera.go
├── gentest/              # Test files and examples
│   ├── CMakeLists.txt
│   ├── config-test.dbc
│   ├── test.c
│   ├── test.sh
│   └── unity/           # Unity test framework
├── go.mod
├── go.sum
└── internal/
    ├── codegen/         # C code generator
    │   ├── codegen.go
    │   └── templates.go
    └── parser/          # DBC file parser
        ├── errors.go
        ├── parser.go
        ├── parser_test.go
        ├── types.go
        ├── utils.go
        └── validator.go

This project is part of the ApexCorse organization.