3.6 KiB

Raw Blame History

{canscope}

CAN bus sniffer and SAE J1939 protocol analyzer. Reads CAN frames from an external process (e.g. candump), decodes them using a J1939 Digital Annex (xlsx), and presents results in an interactive terminal UI or as JSON output.

Features

TUI mode -- full-screen interactive terminal interface (FTXUI). Multiple display modes per CAN ID: deployed, brief, verbose, manual, little-endian
Headless mode -- JSON output to stdout or file, for scripting and automation
Recording -- decoded J1939 SPN values saved to SQLite database with gzip compression and batch flushing
J1939 decoding -- PGN/SPN lookup, bit-level value extraction from payload
CAN playback -- replay recorded CAN frames
Custom SPN configuration -- per-parameter settings, parameter export
Real-time -- 30 fps UI refresh

Build

Requirements:

clang++ with C++23 support
CMake >= 3.13
System libraries: boost (signals2, spirit, phoenix), sqlite3, systemd, zlib

The rest of the dependencies are fetched automatically via CMake FetchContent (FTXUI, tiny-process-library, sqlite_modern_cpp, xlnt, fmt, nlohmann/json, spdlog).

cmake -B build -S . && cmake --build build -j$(nproc)

Binary: build/canscope

Usage

# TUI mode (default)
./build/canscope -e "candump can0" -j1939 thirdparty/j1939da_2018.xlsx

# Headless -- JSON to stdout
./build/canscope -hl -e "candump can0" -j1939 thirdparty/j1939da_2018.xlsx

# Headless -- JSON to file
./build/canscope -hl -e "candump can0" -j1939 thirdparty/j1939da_2018.xlsx -of output.json

# Record to SQLite database
./build/canscope -rec -db recording.db -e "candump can0" -j1939 thirdparty/j1939da_2018.xlsx

# Record + TUI
./build/canscope -rec -db recording.db -tui -e "candump can0" -j1939 thirdparty/j1939da_2018.xlsx

CLI flags

Flag	Long form	Description
`-j1939`	`--j1939-document`	(required) J1939 Digital Annex xlsx file
`-e`	`--execute-command`	Command to read CAN frames from (e.g. `"candump can0"`)
`-hl`	`--headless`	Headless mode (no TUI)
`-of`	`--output-file`	Output file path (headless mode)
`-rec`	`--record`	Record decoded values to SQLite
`-db`	`--database`	SQLite database path (required with `-rec`)
`-tui`		Show TUI alongside recording
`-h`	`--help`	Show help

Architecture

candump / other CAN source
        |  stdout
        v
  aggregator_task ──> shared JSON (mutex-protected)
        |
   diff_task (33ms)
        |
   "new_entry" signal
      /    \
    TUI   headless/recorder

Key components

File	Role
`main.cpp`	Entry point, CLI parsing (clipp), async task orchestration
`xlsx.cpp`	Parses J1939 xlsx into in-memory SQLite (pgns, spns, spn_fragments)
`can_frame.cpp`	Decodes CAN frame against SQLite DB, extracts SPN values
`parsers.hpp`	Boost.Spirit Qi grammars for J1939 field formats
`signals.hpp`	Type-safe signal map (boost::signals2)
`recorder.cpp`	SQLite recording with gzip compression
`mainform.cpp`	Root FTXUI component
`canid_unit.cpp`	Per-CAN-ID display component
`headless.cpp`	Headless JSON output handler

Patterns

Components communicate through a type-safe signal map (signals_map_t)
nlohmann::json as universal data interchange between all layers
Factory functions via extern declarations instead of header includes
std::jthread / std::stop_token for async task management
SIGINT gracefully stops all background tasks

3.6 KiB Raw Blame History