update readme
This commit is contained in:
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README.md
457
README.md
@@ -1,59 +1,63 @@
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DBC Parser Documentation
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Overview
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This module implements a minimal DBC parser intended for use in the FrameTap project.
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# DBC Parser Module Documentation
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## Overview
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This module implements a minimal DBC parser intended for use in the **FrameTap** project.
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Its purpose is to read a DBC file and convert it into an internal representation that can later be used for:
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displaying CAN frames and signals
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- displaying CAN frames and signals
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- building a hierarchical structure for UI
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- integrating with Qt Model/View
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- selecting signals for plotting
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- preparing for runtime CAN/J1939 decoding
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building a hierarchical structure for UI
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The implementation intentionally follows the **KISS principle**:
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integrating with Qt Model/View
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- simple
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- readable
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- easy to modify
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- independent from Qt
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selecting signals for plotting
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This is **not a full DBC parser**, but a practical foundation that can be extended gradually.
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preparing for runtime CAN/J1939 decoding
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---
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The implementation intentionally follows the KISS principle:
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simple
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readable
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easy to modify
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independent from Qt
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This is not a full DBC parser, but a practical foundation that can be extended gradually.
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Architecture
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# Architecture
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The module uses a simple processing pipeline.
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DBC file
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↓
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↓
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DbcParser
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↓
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↓
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DbcDatabase
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↓
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↓
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DbcTreeBuilder
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↓
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↓
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TreeNode hierarchy
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↓
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↓
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Future Qt Model/View integration
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Each component has a clear responsibility.
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Component Responsibility
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DbcParser Reads and parses the DBC file
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DbcDatabase Stores parsed frames and signals
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DbcTreeBuilder Converts the database into a tree
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TreeNode Represents hierarchical nodes
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| Component | Responsibility |
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|-----------|---------------|
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| DbcParser | Reads and parses the DBC file |
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| DbcDatabase | Stores parsed frames and signals |
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| DbcTreeBuilder | Converts the database into a tree |
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| TreeNode | Represents hierarchical nodes |
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This separation allows the parser to remain independent from UI or visualization logic.
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File Structure
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---
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# File Structure
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The module consists of several logical parts.
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Data structures
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## Data structures
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Files:
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@@ -62,7 +66,8 @@ frame_info.h
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dbc_database.h
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These files define the internal representation of parsed data.
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Tree representation
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## Tree representation
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Files:
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@@ -70,7 +75,8 @@ tree_node.h
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tree_node.cpp
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Defines a simple hierarchical structure that can later be used by UI components.
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Parser
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## Parser
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Files:
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@@ -78,7 +84,8 @@ dbc_parser.h
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dbc_parser.cpp
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Responsible for reading the DBC file and extracting frame and signal information.
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Tree builder
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## Tree builder
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Files:
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@@ -86,98 +93,107 @@ dbc_tree_builder.h
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dbc_tree_builder.cpp
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Converts the parsed database into a tree representation.
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Data Structures
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SignalInfo
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---
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# Data Structures
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## SignalInfo
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Represents a single signal defined in a DBC file.
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Fields:
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name
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startBit
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length
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isLittleEndian
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isSigned
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factor
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offset
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minimum
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maximum
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unit
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receivers
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comment
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- name
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- startBit
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- length
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- isLittleEndian
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- isSigned
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- factor
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- offset
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- minimum
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- maximum
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- unit
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- receivers
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- comment
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Notes:
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receivers may contain multiple ECUs
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comment is optional
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factor and offset define physical conversion
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- receivers may contain multiple ECUs
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- comment is optional
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- factor and offset define physical conversion
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Physical value is calculated as:
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physical = raw * factor + offset
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FrameInfo
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---
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## FrameInfo
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Represents a CAN frame.
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Fields:
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name
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canId
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dlc
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transmitter
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comment
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signals
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pgn
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hasPgn
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- name
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- canId
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- dlc
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- transmitter
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- comment
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- signals
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- pgn
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- hasPgn
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Notes:
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signals is a vector of SignalInfo
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- signals is a vector of SignalInfo
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- transmitter is the ECU that sends the frame
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- pgn is derived using simplified J1939 logic
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transmitter is the ECU that sends the frame
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---
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pgn is derived if the frame appears to follow J1939 rules
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DbcDatabase
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## DbcDatabase
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Top level container for parsed data.
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DbcDatabase
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└── vector<FrameInfo>
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└── vector<FrameInfo>
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This structure represents the entire DBC file content.
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Tree Representation
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---
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# Tree Representation
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The module converts the parsed data into a tree.
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Node types:
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Root
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Frame
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Signal
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- Root
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- Frame
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- Signal
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Example structure:
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dbc
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├── EngineData
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│ ├── EngineSpeed
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│ ├── OilTemp
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│ └── CoolantTemp
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└── VehicleData
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├── VehicleSpeed
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└── Odometer
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├── EngineData
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│ ├── EngineSpeed
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│ ├── OilTemp
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│ └── CoolantTemp
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└── VehicleData
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├── VehicleSpeed
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└── Odometer
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Each node stores either:
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FrameInfo
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SignalInfo
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- FrameInfo
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- SignalInfo
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This tree structure is designed to integrate easily with Qt Model/View.
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Parser
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---
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# Parser
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The parser is implemented in:
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@@ -188,62 +204,77 @@ It performs line-based parsing of the DBC file.
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Supported elements:
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BO_
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SG_
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CM_
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- BO_
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- SG_
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- CM_
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Supported DBC Syntax
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Frame Definition
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---
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# Supported DBC Syntax
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## Frame Definition
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Example:
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BO_ 256 EngineData: 8 EEC1
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Parsed values:
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Field Meaning
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256 CAN identifier
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EngineData frame name
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8 DLC
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EEC1 transmitter ECU
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Signal Definition
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| Field | Meaning |
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|------|---------|
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| 256 | CAN identifier |
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| EngineData | frame name |
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| 8 | DLC |
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| EEC1 | transmitter ECU |
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---
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## Signal Definition
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Example:
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SG_ EngineSpeed : 0|16@1+ (0.125,0) [0|8000] "rpm" ECU1,ECU2
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Parsed values:
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Field Meaning
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EngineSpeed signal name
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0 start bit
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16 signal length
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@1 little endian
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+ unsigned
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factor 0.125
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offset 0
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minimum 0
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maximum 8000
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unit rpm
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receivers ECU1, ECU2
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Comments
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Frame comment:
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| Field | Meaning |
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|------|---------|
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| EngineSpeed | signal name |
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| 0 | start bit |
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| 16 | signal length |
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| @1 | little endian |
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| + | unsigned |
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| factor | 0.125 |
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| offset | 0 |
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| minimum | 0 |
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| maximum | 8000 |
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| unit | rpm |
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| receivers | ECU1, ECU2 |
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---
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## Comments
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Frame comment example:
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CM_ BO_ 256 "Engine data frame";
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Signal comment:
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Signal comment example:
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CM_ SG_ 256 EngineSpeed "Actual engine speed";
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These values are stored in:
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Stored in:
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FrameInfo::comment
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SignalInfo::comment
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- FrameInfo::comment
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- SignalInfo::comment
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PGN Extraction
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---
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# PGN Extraction
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PGN is derived using simplified J1939 logic.
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Typical J1939 identifier layout:
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Typical identifier layout:
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Priority
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Reserved
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@@ -252,12 +283,13 @@ PDU Format
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PDU Specific
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Source Address
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The parser extracts PGN from the 29-bit CAN ID.
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The parser extracts PGN from the 29‑bit CAN identifier.
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This is a simplified approximation and should not be considered full J1939 validation.
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Example Usage
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This is only an approximation and not full J1939 validation.
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Typical usage:
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---
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# Example Usage
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DbcParser parser;
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@@ -268,123 +300,134 @@ DbcTreeBuilder builder;
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std::unique_ptr<TreeNode> root = builder.Build(database);
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After this step, the tree can be used by a UI or visualization system.
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Example Tree
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Example output structure:
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---
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# Example Tree
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dbc
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├── EngineData
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│ ├── EngineSpeed
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│ ├── OilTemp
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│ └── CoolantTemp
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└── VehicleData
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├── VehicleSpeed
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└── Odometer
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├── EngineData
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│ ├── EngineSpeed
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│ ├── OilTemp
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│ └── CoolantTemp
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└── VehicleData
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├── VehicleSpeed
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└── Odometer
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Limitations
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---
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# Limitations
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The current implementation intentionally does not support many advanced DBC features.
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Not supported yet:
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multiplexed signals
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BA_ attributes
|
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BA_DEF_ definitions
|
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VAL_ value tables
|
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signal groups
|
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advanced comments
|
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complex syntax variations
|
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- multiplexed signals
|
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- BA_ attributes
|
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- BA_DEF_ definitions
|
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- VAL_ value tables
|
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- signal groups
|
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- complex syntax variations
|
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|
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These can be added later if required.
|
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Design Principles
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KISS
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|
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The parser is intentionally simple.
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---
|
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|
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It avoids complex grammar systems and tokenizers in order to keep the code easy to understand and maintain.
|
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Separation of Concerns
|
||||
# Design Principles
|
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|
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## KISS
|
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|
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The parser avoids complex grammar systems or tokenizers in order to keep the code easy to understand and maintain.
|
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|
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## Separation of Concerns
|
||||
|
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Parsing, storage, and tree building are separate components.
|
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|
||||
This makes it easier to:
|
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This allows reuse for:
|
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|
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test the parser
|
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- GUI display
|
||||
- runtime decoding
|
||||
- export
|
||||
- filtering
|
||||
- testing
|
||||
|
||||
change UI representation
|
||||
|
||||
export data
|
||||
|
||||
reuse the module elsewhere
|
||||
|
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Qt Independence
|
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## Qt Independence
|
||||
|
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The parser itself does not depend on Qt.
|
||||
|
||||
Qt integration should be implemented through a separate adapter layer.
|
||||
Future Development
|
||||
|
||||
---
|
||||
|
||||
# Future Development
|
||||
|
||||
Recommended evolution path.
|
||||
Stage 1 (current)
|
||||
|
||||
BO_
|
||||
SG_
|
||||
CM_
|
||||
transmitter
|
||||
receivers
|
||||
basic PGN extraction
|
||||
tree representation
|
||||
## Stage 1 (current)
|
||||
|
||||
Stage 2
|
||||
- BO_
|
||||
- SG_
|
||||
- CM_
|
||||
- transmitter
|
||||
- receivers
|
||||
- basic PGN extraction
|
||||
- tree representation
|
||||
|
||||
## Stage 2
|
||||
|
||||
Add:
|
||||
|
||||
extended CAN ID detection
|
||||
better PGN extraction
|
||||
TreeNode parent pointer
|
||||
Qt Model adapter
|
||||
- extended CAN ID detection
|
||||
- better PGN extraction
|
||||
- parent pointer in TreeNode
|
||||
- Qt Model adapter
|
||||
|
||||
Stage 3
|
||||
## Stage 3
|
||||
|
||||
Add support for:
|
||||
|
||||
VAL_ value tables
|
||||
BA_ attributes
|
||||
BA_DEF_ definitions
|
||||
extended comments
|
||||
- VAL_ value tables
|
||||
- BA_ attributes
|
||||
- BA_DEF_ definitions
|
||||
- extended comments
|
||||
|
||||
Stage 4
|
||||
## Stage 4
|
||||
|
||||
Advanced functionality:
|
||||
|
||||
multiplexing
|
||||
runtime signal decoding
|
||||
integration with CAN stream
|
||||
drag-and-drop plotting
|
||||
- multiplexing
|
||||
- runtime signal decoding
|
||||
- integration with CAN stream
|
||||
- drag‑and‑drop plotting
|
||||
|
||||
Intended Usage in FrameTap
|
||||
---
|
||||
|
||||
This module will allow FrameTap to:
|
||||
# Intended Usage in FrameTap
|
||||
|
||||
load DBC files
|
||||
display frames and signals
|
||||
select signals
|
||||
search signals
|
||||
display metadata
|
||||
prepare runtime decoding
|
||||
This module allows FrameTap to:
|
||||
|
||||
- load DBC files
|
||||
- display frames and signals
|
||||
- select signals
|
||||
- search signals
|
||||
- display metadata
|
||||
- prepare runtime decoding
|
||||
|
||||
Example workflow:
|
||||
|
||||
Load DBC
|
||||
↓
|
||||
↓
|
||||
Browse signals
|
||||
↓
|
||||
↓
|
||||
Select signal
|
||||
↓
|
||||
↓
|
||||
Decode CAN frames
|
||||
↓
|
||||
↓
|
||||
Plot physical values
|
||||
|
||||
Why Abstract Factory Is Not Used
|
||||
---
|
||||
|
||||
# Why Abstract Factory Is Not Used
|
||||
|
||||
An abstract factory is intentionally not used at this stage.
|
||||
|
||||
@@ -392,40 +435,44 @@ The current structure already separates responsibilities clearly:
|
||||
|
||||
parser → database → tree builder → tree
|
||||
|
||||
Introducing factories now would increase complexity without significant benefit.
|
||||
Factories can be introduced later if multiple internal representations become necessary.
|
||||
|
||||
Factories can be added later if multiple internal representations are required.
|
||||
Build Integration
|
||||
---
|
||||
|
||||
# Build Integration
|
||||
|
||||
The module is independent of any specific build system.
|
||||
|
||||
It can be integrated using:
|
||||
|
||||
CMake
|
||||
qmake
|
||||
Makefile
|
||||
- CMake
|
||||
- qmake
|
||||
- Makefile
|
||||
|
||||
Simply add the source files to the project.
|
||||
Summary
|
||||
Simply include the source files in your project.
|
||||
|
||||
This module provides a minimal but extensible DBC parser designed for FrameTap.
|
||||
---
|
||||
|
||||
# Summary
|
||||
|
||||
This module provides a minimal but extensible DBC parser designed for **FrameTap**.
|
||||
|
||||
Key properties:
|
||||
|
||||
simple
|
||||
modular
|
||||
Qt-independent
|
||||
extendable
|
||||
- simple
|
||||
- modular
|
||||
- Qt‑independent
|
||||
- extendable
|
||||
|
||||
It converts a DBC file into an internal structure:
|
||||
|
||||
frame → signals
|
||||
|
||||
with additional metadata such as:
|
||||
with metadata such as:
|
||||
|
||||
transmitter
|
||||
receivers
|
||||
comments
|
||||
basic PGN information
|
||||
- transmitter
|
||||
- receivers
|
||||
- comments
|
||||
- basic PGN information
|
||||
|
||||
This forms the foundation for future CAN signal visualization and decoding.
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Reference in New Issue
Block a user